8205940: LoadNode::find_previous_arraycopy fails with "broken allocation" assert
Summary: Removed assert which is too strong.
Reviewed-by: roland
/*
* Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "classfile/systemDictionary.hpp"
#include "compiler/compileLog.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "oops/objArrayKlass.hpp"
#include "opto/addnode.hpp"
#include "opto/arraycopynode.hpp"
#include "opto/cfgnode.hpp"
#include "opto/compile.hpp"
#include "opto/connode.hpp"
#include "opto/convertnode.hpp"
#include "opto/loopnode.hpp"
#include "opto/machnode.hpp"
#include "opto/matcher.hpp"
#include "opto/memnode.hpp"
#include "opto/mulnode.hpp"
#include "opto/narrowptrnode.hpp"
#include "opto/phaseX.hpp"
#include "opto/regmask.hpp"
#include "utilities/align.hpp"
#include "utilities/copy.hpp"
#include "utilities/macros.hpp"
#include "utilities/vmError.hpp"
#if INCLUDE_ZGC
#include "gc/z/c2/zBarrierSetC2.hpp"
#endif
// Portions of code courtesy of Clifford Click
// Optimization - Graph Style
static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
//=============================================================================
uint MemNode::size_of() const { return sizeof(*this); }
const TypePtr *MemNode::adr_type() const {
Node* adr = in(Address);
if (adr == NULL) return NULL; // node is dead
const TypePtr* cross_check = NULL;
DEBUG_ONLY(cross_check = _adr_type);
return calculate_adr_type(adr->bottom_type(), cross_check);
}
bool MemNode::check_if_adr_maybe_raw(Node* adr) {
if (adr != NULL) {
if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
return true;
}
}
return false;
}
#ifndef PRODUCT
void MemNode::dump_spec(outputStream *st) const {
if (in(Address) == NULL) return; // node is dead
#ifndef ASSERT
// fake the missing field
const TypePtr* _adr_type = NULL;
if (in(Address) != NULL)
_adr_type = in(Address)->bottom_type()->isa_ptr();
#endif
dump_adr_type(this, _adr_type, st);
Compile* C = Compile::current();
if (C->alias_type(_adr_type)->is_volatile()) {
st->print(" Volatile!");
}
if (_unaligned_access) {
st->print(" unaligned");
}
if (_mismatched_access) {
st->print(" mismatched");
}
}
void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
st->print(" @");
if (adr_type == NULL) {
st->print("NULL");
} else {
adr_type->dump_on(st);
Compile* C = Compile::current();
Compile::AliasType* atp = NULL;
if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
if (atp == NULL)
st->print(", idx=?\?;");
else if (atp->index() == Compile::AliasIdxBot)
st->print(", idx=Bot;");
else if (atp->index() == Compile::AliasIdxTop)
st->print(", idx=Top;");
else if (atp->index() == Compile::AliasIdxRaw)
st->print(", idx=Raw;");
else {
ciField* field = atp->field();
if (field) {
st->print(", name=");
field->print_name_on(st);
}
st->print(", idx=%d;", atp->index());
}
}
}
extern void print_alias_types();
#endif
Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
assert((t_oop != NULL), "sanity");
bool is_instance = t_oop->is_known_instance_field();
bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
(load != NULL) && load->is_Load() &&
(phase->is_IterGVN() != NULL);
if (!(is_instance || is_boxed_value_load))
return mchain; // don't try to optimize non-instance types
uint instance_id = t_oop->instance_id();
Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
Node *prev = NULL;
Node *result = mchain;
while (prev != result) {
prev = result;
if (result == start_mem)
break; // hit one of our sentinels
// skip over a call which does not affect this memory slice
if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
Node *proj_in = result->in(0);
if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
break; // hit one of our sentinels
} else if (proj_in->is_Call()) {
// ArrayCopyNodes processed here as well
CallNode *call = proj_in->as_Call();
if (!call->may_modify(t_oop, phase)) { // returns false for instances
result = call->in(TypeFunc::Memory);
}
} else if (proj_in->is_Initialize()) {
AllocateNode* alloc = proj_in->as_Initialize()->allocation();
// Stop if this is the initialization for the object instance which
// contains this memory slice, otherwise skip over it.
if ((alloc == NULL) || (alloc->_idx == instance_id)) {
break;
}
if (is_instance) {
result = proj_in->in(TypeFunc::Memory);
} else if (is_boxed_value_load) {
Node* klass = alloc->in(AllocateNode::KlassNode);
const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
result = proj_in->in(TypeFunc::Memory); // not related allocation
}
}
} else if (proj_in->is_MemBar()) {
ArrayCopyNode* ac = NULL;
if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
break;
}
result = proj_in->in(TypeFunc::Memory);
} else {
assert(false, "unexpected projection");
}
} else if (result->is_ClearArray()) {
if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
// Can not bypass initialization of the instance
// we are looking for.
break;
}
// Otherwise skip it (the call updated 'result' value).
} else if (result->is_MergeMem()) {
result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
}
}
return result;
}
Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
const TypeOopPtr* t_oop = t_adr->isa_oopptr();
if (t_oop == NULL)
return mchain; // don't try to optimize non-oop types
Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
bool is_instance = t_oop->is_known_instance_field();
PhaseIterGVN *igvn = phase->is_IterGVN();
if (is_instance && igvn != NULL && result->is_Phi()) {
PhiNode *mphi = result->as_Phi();
assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
const TypePtr *t = mphi->adr_type();
if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
(t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
t->is_oopptr()->cast_to_exactness(true)
->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
// clone the Phi with our address type
result = mphi->split_out_instance(t_adr, igvn);
} else {
assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
}
}
return result;
}
static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
uint alias_idx = phase->C->get_alias_index(tp);
Node *mem = mmem;
#ifdef ASSERT
{
// Check that current type is consistent with the alias index used during graph construction
assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
bool consistent = adr_check == NULL || adr_check->empty() ||
phase->C->must_alias(adr_check, alias_idx );
// Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
if( !consistent && adr_check != NULL && !adr_check->empty() &&
tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
// don't assert if it is dead code.
consistent = true;
}
if( !consistent ) {
st->print("alias_idx==%d, adr_check==", alias_idx);
if( adr_check == NULL ) {
st->print("NULL");
} else {
adr_check->dump();
}
st->cr();
print_alias_types();
assert(consistent, "adr_check must match alias idx");
}
}
#endif
// TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
// means an array I have not precisely typed yet. Do not do any
// alias stuff with it any time soon.
const TypeOopPtr *toop = tp->isa_oopptr();
if( tp->base() != Type::AnyPtr &&
!(toop &&
toop->klass() != NULL &&
toop->klass()->is_java_lang_Object() &&
toop->offset() == Type::OffsetBot) ) {
// compress paths and change unreachable cycles to TOP
// If not, we can update the input infinitely along a MergeMem cycle
// Equivalent code in PhiNode::Ideal
Node* m = phase->transform(mmem);
// If transformed to a MergeMem, get the desired slice
// Otherwise the returned node represents memory for every slice
mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
// Update input if it is progress over what we have now
}
return mem;
}
//--------------------------Ideal_common---------------------------------------
// Look for degenerate control and memory inputs. Bypass MergeMem inputs.
// Unhook non-raw memories from complete (macro-expanded) initializations.
Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
// If our control input is a dead region, kill all below the region
Node *ctl = in(MemNode::Control);
if (ctl && remove_dead_region(phase, can_reshape))
return this;
ctl = in(MemNode::Control);
// Don't bother trying to transform a dead node
if (ctl && ctl->is_top()) return NodeSentinel;
PhaseIterGVN *igvn = phase->is_IterGVN();
// Wait if control on the worklist.
if (ctl && can_reshape && igvn != NULL) {
Node* bol = NULL;
Node* cmp = NULL;
if (ctl->in(0)->is_If()) {
assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
bol = ctl->in(0)->in(1);
if (bol->is_Bool())
cmp = ctl->in(0)->in(1)->in(1);
}
if (igvn->_worklist.member(ctl) ||
(bol != NULL && igvn->_worklist.member(bol)) ||
(cmp != NULL && igvn->_worklist.member(cmp)) ) {
// This control path may be dead.
// Delay this memory node transformation until the control is processed.
phase->is_IterGVN()->_worklist.push(this);
return NodeSentinel; // caller will return NULL
}
}
// Ignore if memory is dead, or self-loop
Node *mem = in(MemNode::Memory);
if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
assert(mem != this, "dead loop in MemNode::Ideal");
if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
// This memory slice may be dead.
// Delay this mem node transformation until the memory is processed.
phase->is_IterGVN()->_worklist.push(this);
return NodeSentinel; // caller will return NULL
}
Node *address = in(MemNode::Address);
const Type *t_adr = phase->type(address);
if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
if (can_reshape && igvn != NULL &&
(igvn->_worklist.member(address) ||
(igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
// The address's base and type may change when the address is processed.
// Delay this mem node transformation until the address is processed.
phase->is_IterGVN()->_worklist.push(this);
return NodeSentinel; // caller will return NULL
}
// Do NOT remove or optimize the next lines: ensure a new alias index
// is allocated for an oop pointer type before Escape Analysis.
// Note: C++ will not remove it since the call has side effect.
if (t_adr->isa_oopptr()) {
int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
}
Node* base = NULL;
if (address->is_AddP()) {
base = address->in(AddPNode::Base);
}
if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
!t_adr->isa_rawptr()) {
// Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
// Skip this node optimization if its address has TOP base.
return NodeSentinel; // caller will return NULL
}
// Avoid independent memory operations
Node* old_mem = mem;
// The code which unhooks non-raw memories from complete (macro-expanded)
// initializations was removed. After macro-expansion all stores catched
// by Initialize node became raw stores and there is no information
// which memory slices they modify. So it is unsafe to move any memory
// operation above these stores. Also in most cases hooked non-raw memories
// were already unhooked by using information from detect_ptr_independence()
// and find_previous_store().
if (mem->is_MergeMem()) {
MergeMemNode* mmem = mem->as_MergeMem();
const TypePtr *tp = t_adr->is_ptr();
mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
}
if (mem != old_mem) {
set_req(MemNode::Memory, mem);
if (can_reshape && old_mem->outcnt() == 0) {
igvn->_worklist.push(old_mem);
}
if (phase->type( mem ) == Type::TOP) return NodeSentinel;
return this;
}
// let the subclass continue analyzing...
return NULL;
}
// Helper function for proving some simple control dominations.
// Attempt to prove that all control inputs of 'dom' dominate 'sub'.
// Already assumes that 'dom' is available at 'sub', and that 'sub'
// is not a constant (dominated by the method's StartNode).
// Used by MemNode::find_previous_store to prove that the
// control input of a memory operation predates (dominates)
// an allocation it wants to look past.
bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
return false; // Conservative answer for dead code
// Check 'dom'. Skip Proj and CatchProj nodes.
dom = dom->find_exact_control(dom);
if (dom == NULL || dom->is_top())
return false; // Conservative answer for dead code
if (dom == sub) {
// For the case when, for example, 'sub' is Initialize and the original
// 'dom' is Proj node of the 'sub'.
return false;
}
if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
return true;
// 'dom' dominates 'sub' if its control edge and control edges
// of all its inputs dominate or equal to sub's control edge.
// Currently 'sub' is either Allocate, Initialize or Start nodes.
// Or Region for the check in LoadNode::Ideal();
// 'sub' should have sub->in(0) != NULL.
assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
sub->is_Region() || sub->is_Call(), "expecting only these nodes");
// Get control edge of 'sub'.
Node* orig_sub = sub;
sub = sub->find_exact_control(sub->in(0));
if (sub == NULL || sub->is_top())
return false; // Conservative answer for dead code
assert(sub->is_CFG(), "expecting control");
if (sub == dom)
return true;
if (sub->is_Start() || sub->is_Root())
return false;
{
// Check all control edges of 'dom'.
ResourceMark rm;
Arena* arena = Thread::current()->resource_area();
Node_List nlist(arena);
Unique_Node_List dom_list(arena);
dom_list.push(dom);
bool only_dominating_controls = false;
for (uint next = 0; next < dom_list.size(); next++) {
Node* n = dom_list.at(next);
if (n == orig_sub)
return false; // One of dom's inputs dominated by sub.
if (!n->is_CFG() && n->pinned()) {
// Check only own control edge for pinned non-control nodes.
n = n->find_exact_control(n->in(0));
if (n == NULL || n->is_top())
return false; // Conservative answer for dead code
assert(n->is_CFG(), "expecting control");
dom_list.push(n);
} else if (n->is_Con() || n->is_Start() || n->is_Root()) {
only_dominating_controls = true;
} else if (n->is_CFG()) {
if (n->dominates(sub, nlist))
only_dominating_controls = true;
else
return false;
} else {
// First, own control edge.
Node* m = n->find_exact_control(n->in(0));
if (m != NULL) {
if (m->is_top())
return false; // Conservative answer for dead code
dom_list.push(m);
}
// Now, the rest of edges.
uint cnt = n->req();
for (uint i = 1; i < cnt; i++) {
m = n->find_exact_control(n->in(i));
if (m == NULL || m->is_top())
continue;
dom_list.push(m);
}
}
}
return only_dominating_controls;
}
}
//---------------------detect_ptr_independence---------------------------------
// Used by MemNode::find_previous_store to prove that two base
// pointers are never equal.
// The pointers are accompanied by their associated allocations,
// if any, which have been previously discovered by the caller.
bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
Node* p2, AllocateNode* a2,
PhaseTransform* phase) {
// Attempt to prove that these two pointers cannot be aliased.
// They may both manifestly be allocations, and they should differ.
// Or, if they are not both allocations, they can be distinct constants.
// Otherwise, one is an allocation and the other a pre-existing value.
if (a1 == NULL && a2 == NULL) { // neither an allocation
return (p1 != p2) && p1->is_Con() && p2->is_Con();
} else if (a1 != NULL && a2 != NULL) { // both allocations
return (a1 != a2);
} else if (a1 != NULL) { // one allocation a1
// (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
return all_controls_dominate(p2, a1);
} else { //(a2 != NULL) // one allocation a2
return all_controls_dominate(p1, a2);
}
return false;
}
// Find an arraycopy that must have set (can_see_stored_value=true) or
// could have set (can_see_stored_value=false) the value for this load
Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
Node* mb = mem->in(0);
if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
if (ac->is_clonebasic()) {
intptr_t offset;
AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
if (alloc != NULL && alloc == ld_alloc) {
return ac;
}
}
}
} else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
if (ac->is_arraycopy_validated() ||
ac->is_copyof_validated() ||
ac->is_copyofrange_validated()) {
Node* ld_addp = in(MemNode::Address);
if (ld_addp->is_AddP()) {
Node* ld_base = ld_addp->in(AddPNode::Address);
Node* ld_offs = ld_addp->in(AddPNode::Offset);
Node* dest = ac->in(ArrayCopyNode::Dest);
if (dest == ld_base) {
const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
return ac;
}
if (!can_see_stored_value) {
mem = ac->in(TypeFunc::Memory);
}
}
}
}
}
return NULL;
}
// The logic for reordering loads and stores uses four steps:
// (a) Walk carefully past stores and initializations which we
// can prove are independent of this load.
// (b) Observe that the next memory state makes an exact match
// with self (load or store), and locate the relevant store.
// (c) Ensure that, if we were to wire self directly to the store,
// the optimizer would fold it up somehow.
// (d) Do the rewiring, and return, depending on some other part of
// the optimizer to fold up the load.
// This routine handles steps (a) and (b). Steps (c) and (d) are
// specific to loads and stores, so they are handled by the callers.
// (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
//
Node* MemNode::find_previous_store(PhaseTransform* phase) {
Node* ctrl = in(MemNode::Control);
Node* adr = in(MemNode::Address);
intptr_t offset = 0;
Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
if (offset == Type::OffsetBot)
return NULL; // cannot unalias unless there are precise offsets
const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
intptr_t size_in_bytes = memory_size();
Node* mem = in(MemNode::Memory); // start searching here...
int cnt = 50; // Cycle limiter
for (;;) { // While we can dance past unrelated stores...
if (--cnt < 0) break; // Caught in cycle or a complicated dance?
Node* prev = mem;
if (mem->is_Store()) {
Node* st_adr = mem->in(MemNode::Address);
intptr_t st_offset = 0;
Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
if (st_base == NULL)
break; // inscrutable pointer
// For raw accesses it's not enough to prove that constant offsets don't intersect.
// We need the bases to be the equal in order for the offset check to make sense.
if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
break;
}
if (st_offset != offset && st_offset != Type::OffsetBot) {
const int MAX_STORE = BytesPerLong;
if (st_offset >= offset + size_in_bytes ||
st_offset <= offset - MAX_STORE ||
st_offset <= offset - mem->as_Store()->memory_size()) {
// Success: The offsets are provably independent.
// (You may ask, why not just test st_offset != offset and be done?
// The answer is that stores of different sizes can co-exist
// in the same sequence of RawMem effects. We sometimes initialize
// a whole 'tile' of array elements with a single jint or jlong.)
mem = mem->in(MemNode::Memory);
continue; // (a) advance through independent store memory
}
}
if (st_base != base &&
detect_ptr_independence(base, alloc,
st_base,
AllocateNode::Ideal_allocation(st_base, phase),
phase)) {
// Success: The bases are provably independent.
mem = mem->in(MemNode::Memory);
continue; // (a) advance through independent store memory
}
// (b) At this point, if the bases or offsets do not agree, we lose,
// since we have not managed to prove 'this' and 'mem' independent.
if (st_base == base && st_offset == offset) {
return mem; // let caller handle steps (c), (d)
}
} else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
InitializeNode* st_init = mem->in(0)->as_Initialize();
AllocateNode* st_alloc = st_init->allocation();
if (st_alloc == NULL)
break; // something degenerated
bool known_identical = false;
bool known_independent = false;
if (alloc == st_alloc)
known_identical = true;
else if (alloc != NULL)
known_independent = true;
else if (all_controls_dominate(this, st_alloc))
known_independent = true;
if (known_independent) {
// The bases are provably independent: Either they are
// manifestly distinct allocations, or else the control
// of this load dominates the store's allocation.
int alias_idx = phase->C->get_alias_index(adr_type());
if (alias_idx == Compile::AliasIdxRaw) {
mem = st_alloc->in(TypeFunc::Memory);
} else {
mem = st_init->memory(alias_idx);
}
continue; // (a) advance through independent store memory
}
// (b) at this point, if we are not looking at a store initializing
// the same allocation we are loading from, we lose.
if (known_identical) {
// From caller, can_see_stored_value will consult find_captured_store.
return mem; // let caller handle steps (c), (d)
}
} else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
if (prev != mem) {
// Found an arraycopy but it doesn't affect that load
continue;
}
// Found an arraycopy that may affect that load
return mem;
} else if (addr_t != NULL && addr_t->is_known_instance_field()) {
// Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
if (mem->is_Proj() && mem->in(0)->is_Call()) {
// ArrayCopyNodes processed here as well.
CallNode *call = mem->in(0)->as_Call();
if (!call->may_modify(addr_t, phase)) {
mem = call->in(TypeFunc::Memory);
continue; // (a) advance through independent call memory
}
} else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
ArrayCopyNode* ac = NULL;
if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
break;
}
mem = mem->in(0)->in(TypeFunc::Memory);
continue; // (a) advance through independent MemBar memory
} else if (mem->is_ClearArray()) {
if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
// (the call updated 'mem' value)
continue; // (a) advance through independent allocation memory
} else {
// Can not bypass initialization of the instance
// we are looking for.
return mem;
}
} else if (mem->is_MergeMem()) {
int alias_idx = phase->C->get_alias_index(adr_type());
mem = mem->as_MergeMem()->memory_at(alias_idx);
continue; // (a) advance through independent MergeMem memory
}
}
// Unless there is an explicit 'continue', we must bail out here,
// because 'mem' is an inscrutable memory state (e.g., a call).
break;
}
return NULL; // bail out
}
//----------------------calculate_adr_type-------------------------------------
// Helper function. Notices when the given type of address hits top or bottom.
// Also, asserts a cross-check of the type against the expected address type.
const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
if (t == Type::TOP) return NULL; // does not touch memory any more?
#ifdef PRODUCT
cross_check = NULL;
#else
if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
#endif
const TypePtr* tp = t->isa_ptr();
if (tp == NULL) {
assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
return TypePtr::BOTTOM; // touches lots of memory
} else {
#ifdef ASSERT
// %%%% [phh] We don't check the alias index if cross_check is
// TypeRawPtr::BOTTOM. Needs to be investigated.
if (cross_check != NULL &&
cross_check != TypePtr::BOTTOM &&
cross_check != TypeRawPtr::BOTTOM) {
// Recheck the alias index, to see if it has changed (due to a bug).
Compile* C = Compile::current();
assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
"must stay in the original alias category");
// The type of the address must be contained in the adr_type,
// disregarding "null"-ness.
// (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
"real address must not escape from expected memory type");
}
#endif
return tp;
}
}
//=============================================================================
// Should LoadNode::Ideal() attempt to remove control edges?
bool LoadNode::can_remove_control() const {
return true;
}
uint LoadNode::size_of() const { return sizeof(*this); }
uint LoadNode::cmp( const Node &n ) const
{ return !Type::cmp( _type, ((LoadNode&)n)._type ); }
const Type *LoadNode::bottom_type() const { return _type; }
uint LoadNode::ideal_reg() const {
return _type->ideal_reg();
}
#ifndef PRODUCT
void LoadNode::dump_spec(outputStream *st) const {
MemNode::dump_spec(st);
if( !Verbose && !WizardMode ) {
// standard dump does this in Verbose and WizardMode
st->print(" #"); _type->dump_on(st);
}
if (!depends_only_on_test()) {
st->print(" (does not depend only on test)");
}
}
#endif
#ifdef ASSERT
//----------------------------is_immutable_value-------------------------------
// Helper function to allow a raw load without control edge for some cases
bool LoadNode::is_immutable_value(Node* adr) {
return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
(adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
in_bytes(JavaThread::osthread_offset())));
}
#endif
//----------------------------LoadNode::make-----------------------------------
// Polymorphic factory method:
Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
ControlDependency control_dependency, bool unaligned, bool mismatched) {
Compile* C = gvn.C;
// sanity check the alias category against the created node type
assert(!(adr_type->isa_oopptr() &&
adr_type->offset() == oopDesc::klass_offset_in_bytes()),
"use LoadKlassNode instead");
assert(!(adr_type->isa_aryptr() &&
adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
"use LoadRangeNode instead");
// Check control edge of raw loads
assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
// oop will be recorded in oop map if load crosses safepoint
rt->isa_oopptr() || is_immutable_value(adr),
"raw memory operations should have control edge");
LoadNode* load = NULL;
switch (bt) {
case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
case T_OBJECT:
#ifdef _LP64
if (adr->bottom_type()->is_ptr_to_narrowoop()) {
load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
} else
#endif
{
assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
}
break;
default:
// ShouldNotReachHere(); ???
break;
}
assert(load != NULL, "LoadNode should have been created");
if (unaligned) {
load->set_unaligned_access();
}
if (mismatched) {
load->set_mismatched_access();
}
if (load->Opcode() == Op_LoadN) {
Node* ld = gvn.transform(load);
return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
}
return load;
}
LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
ControlDependency control_dependency, bool unaligned, bool mismatched) {
bool require_atomic = true;
LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
if (unaligned) {
load->set_unaligned_access();
}
if (mismatched) {
load->set_mismatched_access();
}
return load;
}
LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
ControlDependency control_dependency, bool unaligned, bool mismatched) {
bool require_atomic = true;
LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
if (unaligned) {
load->set_unaligned_access();
}
if (mismatched) {
load->set_mismatched_access();
}
return load;
}
//------------------------------hash-------------------------------------------
uint LoadNode::hash() const {
// unroll addition of interesting fields
return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
}
static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
bool is_stable_ary = FoldStableValues &&
(tp != NULL) && (tp->isa_aryptr() != NULL) &&
tp->isa_aryptr()->is_stable();
return (eliminate_boxing && non_volatile) || is_stable_ary;
}
return false;
}
// Is the value loaded previously stored by an arraycopy? If so return
// a load node that reads from the source array so we may be able to
// optimize out the ArrayCopy node later.
Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
#if INCLUDE_ZGC
if (UseZGC) {
if (bottom_type()->make_oopptr() != NULL) {
return NULL;
}
}
#endif
Node* ld_adr = in(MemNode::Address);
intptr_t ld_off = 0;
AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
if (ac != NULL) {
assert(ac->is_ArrayCopy(), "what kind of node can this be?");
Node* mem = ac->in(TypeFunc::Memory);
Node* ctl = ac->in(0);
Node* src = ac->in(ArrayCopyNode::Src);
if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
return NULL;
}
LoadNode* ld = clone()->as_Load();
Node* addp = in(MemNode::Address)->clone();
if (ac->as_ArrayCopy()->is_clonebasic()) {
assert(ld_alloc != NULL, "need an alloc");
assert(addp->is_AddP(), "address must be addp");
assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
addp->set_req(AddPNode::Base, src->in(AddPNode::Base));
addp->set_req(AddPNode::Address, src->in(AddPNode::Address));
} else {
assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
ac->as_ArrayCopy()->is_copyof_validated() ||
ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
addp->set_req(AddPNode::Base, src);
addp->set_req(AddPNode::Address, src);
const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
uint shift = exact_log2(type2aelembytes(ary_elem));
Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
#ifdef _LP64
diff = phase->transform(new ConvI2LNode(diff));
#endif
diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
addp->set_req(AddPNode::Offset, offset);
}
addp = phase->transform(addp);
#ifdef ASSERT
const TypePtr* adr_type = phase->type(addp)->is_ptr();
ld->_adr_type = adr_type;
#endif
ld->set_req(MemNode::Address, addp);
ld->set_req(0, ctl);
ld->set_req(MemNode::Memory, mem);
// load depends on the tests that validate the arraycopy
ld->_control_dependency = Pinned;
return ld;
}
return NULL;
}
//---------------------------can_see_stored_value------------------------------
// This routine exists to make sure this set of tests is done the same
// everywhere. We need to make a coordinated change: first LoadNode::Ideal
// will change the graph shape in a way which makes memory alive twice at the
// same time (uses the Oracle model of aliasing), then some
// LoadXNode::Identity will fold things back to the equivalence-class model
// of aliasing.
Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
Node* ld_adr = in(MemNode::Address);
intptr_t ld_off = 0;
AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
// This is more general than load from boxing objects.
if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
uint alias_idx = atp->index();
bool final = !atp->is_rewritable();
Node* result = NULL;
Node* current = st;
// Skip through chains of MemBarNodes checking the MergeMems for
// new states for the slice of this load. Stop once any other
// kind of node is encountered. Loads from final memory can skip
// through any kind of MemBar but normal loads shouldn't skip
// through MemBarAcquire since the could allow them to move out of
// a synchronized region.
while (current->is_Proj()) {
int opc = current->in(0)->Opcode();
if ((final && (opc == Op_MemBarAcquire ||
opc == Op_MemBarAcquireLock ||
opc == Op_LoadFence)) ||
opc == Op_MemBarRelease ||
opc == Op_StoreFence ||
opc == Op_MemBarReleaseLock ||
opc == Op_MemBarStoreStore ||
opc == Op_MemBarCPUOrder) {
Node* mem = current->in(0)->in(TypeFunc::Memory);
if (mem->is_MergeMem()) {
MergeMemNode* merge = mem->as_MergeMem();
Node* new_st = merge->memory_at(alias_idx);
if (new_st == merge->base_memory()) {
// Keep searching
current = new_st;
continue;
}
// Save the new memory state for the slice and fall through
// to exit.
result = new_st;
}
}
break;
}
if (result != NULL) {
st = result;
}
}
// Loop around twice in the case Load -> Initialize -> Store.
// (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
for (int trip = 0; trip <= 1; trip++) {
if (st->is_Store()) {
Node* st_adr = st->in(MemNode::Address);
if (!phase->eqv(st_adr, ld_adr)) {
// Try harder before giving up... Match raw and non-raw pointers.
intptr_t st_off = 0;
AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
if (alloc == NULL) return NULL;
if (alloc != ld_alloc) return NULL;
if (ld_off != st_off) return NULL;
// At this point we have proven something like this setup:
// A = Allocate(...)
// L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
// S = StoreQ(, AddP(, A.Parm , #Off), V)
// (Actually, we haven't yet proven the Q's are the same.)
// In other words, we are loading from a casted version of
// the same pointer-and-offset that we stored to.
// Thus, we are able to replace L by V.
}
// Now prove that we have a LoadQ matched to a StoreQ, for some Q.
if (store_Opcode() != st->Opcode())
return NULL;
return st->in(MemNode::ValueIn);
}
// A load from a freshly-created object always returns zero.
// (This can happen after LoadNode::Ideal resets the load's memory input
// to find_captured_store, which returned InitializeNode::zero_memory.)
if (st->is_Proj() && st->in(0)->is_Allocate() &&
(st->in(0) == ld_alloc) &&
(ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
// return a zero value for the load's basic type
// (This is one of the few places where a generic PhaseTransform
// can create new nodes. Think of it as lazily manifesting
// virtually pre-existing constants.)
return phase->zerocon(memory_type());
}
// A load from an initialization barrier can match a captured store.
if (st->is_Proj() && st->in(0)->is_Initialize()) {
InitializeNode* init = st->in(0)->as_Initialize();
AllocateNode* alloc = init->allocation();
if ((alloc != NULL) && (alloc == ld_alloc)) {
// examine a captured store value
st = init->find_captured_store(ld_off, memory_size(), phase);
if (st != NULL) {
continue; // take one more trip around
}
}
}
// Load boxed value from result of valueOf() call is input parameter.
if (this->is_Load() && ld_adr->is_AddP() &&
(tp != NULL) && tp->is_ptr_to_boxed_value()) {
intptr_t ignore = 0;
Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
if (base != NULL && base->is_Proj() &&
base->as_Proj()->_con == TypeFunc::Parms &&
base->in(0)->is_CallStaticJava() &&
base->in(0)->as_CallStaticJava()->is_boxing_method()) {
return base->in(0)->in(TypeFunc::Parms);
}
}
break;
}
return NULL;
}
//----------------------is_instance_field_load_with_local_phi------------------
bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
in(Address)->is_AddP() ) {
const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
// Only instances and boxed values.
if( t_oop != NULL &&
(t_oop->is_ptr_to_boxed_value() ||
t_oop->is_known_instance_field()) &&
t_oop->offset() != Type::OffsetBot &&
t_oop->offset() != Type::OffsetTop) {
return true;
}
}
return false;
}
//------------------------------Identity---------------------------------------
// Loads are identity if previous store is to same address
Node* LoadNode::Identity(PhaseGVN* phase) {
// If the previous store-maker is the right kind of Store, and the store is
// to the same address, then we are equal to the value stored.
Node* mem = in(Memory);
Node* value = can_see_stored_value(mem, phase);
if( value ) {
// byte, short & char stores truncate naturally.
// A load has to load the truncated value which requires
// some sort of masking operation and that requires an
// Ideal call instead of an Identity call.
if (memory_size() < BytesPerInt) {
// If the input to the store does not fit with the load's result type,
// it must be truncated via an Ideal call.
if (!phase->type(value)->higher_equal(phase->type(this)))
return this;
}
// (This works even when value is a Con, but LoadNode::Value
// usually runs first, producing the singleton type of the Con.)
return value;
}
// Search for an existing data phi which was generated before for the same
// instance's field to avoid infinite generation of phis in a loop.
Node *region = mem->in(0);
if (is_instance_field_load_with_local_phi(region)) {
const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
int this_index = phase->C->get_alias_index(addr_t);
int this_offset = addr_t->offset();
int this_iid = addr_t->instance_id();
if (!addr_t->is_known_instance() &&
addr_t->is_ptr_to_boxed_value()) {
// Use _idx of address base (could be Phi node) for boxed values.
intptr_t ignore = 0;
Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
if (base == NULL) {
return this;
}
this_iid = base->_idx;
}
const Type* this_type = bottom_type();
for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
Node* phi = region->fast_out(i);
if (phi->is_Phi() && phi != mem &&
phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
return phi;
}
}
}
return this;
}
// Construct an equivalent unsigned load.
Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
BasicType bt = T_ILLEGAL;
const Type* rt = NULL;
switch (Opcode()) {
case Op_LoadUB: return this;
case Op_LoadUS: return this;
case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
default:
assert(false, "no unsigned variant: %s", Name());
return NULL;
}
return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
raw_adr_type(), rt, bt, _mo, _control_dependency,
is_unaligned_access(), is_mismatched_access());
}
// Construct an equivalent signed load.
Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
BasicType bt = T_ILLEGAL;
const Type* rt = NULL;
switch (Opcode()) {
case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
case Op_LoadB: // fall through
case Op_LoadS: // fall through
case Op_LoadI: // fall through
case Op_LoadL: return this;
default:
assert(false, "no signed variant: %s", Name());
return NULL;
}
return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
raw_adr_type(), rt, bt, _mo, _control_dependency,
is_unaligned_access(), is_mismatched_access());
}
// We're loading from an object which has autobox behaviour.
// If this object is result of a valueOf call we'll have a phi
// merging a newly allocated object and a load from the cache.
// We want to replace this load with the original incoming
// argument to the valueOf call.
Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
assert(phase->C->eliminate_boxing(), "sanity");
intptr_t ignore = 0;
Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
if ((base == NULL) || base->is_Phi()) {
// Push the loads from the phi that comes from valueOf up
// through it to allow elimination of the loads and the recovery
// of the original value. It is done in split_through_phi().
return NULL;
} else if (base->is_Load() ||
(base->is_DecodeN() && base->in(1)->is_Load())) {
// Eliminate the load of boxed value for integer types from the cache
// array by deriving the value from the index into the array.
// Capture the offset of the load and then reverse the computation.
// Get LoadN node which loads a boxing object from 'cache' array.
if (base->is_DecodeN()) {
base = base->in(1);
}
if (!base->in(Address)->is_AddP()) {
return NULL; // Complex address
}
AddPNode* address = base->in(Address)->as_AddP();
Node* cache_base = address->in(AddPNode::Base);
if ((cache_base != NULL) && cache_base->is_DecodeN()) {
// Get ConP node which is static 'cache' field.
cache_base = cache_base->in(1);
}
if ((cache_base != NULL) && cache_base->is_Con()) {
const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
if ((base_type != NULL) && base_type->is_autobox_cache()) {
Node* elements[4];
int shift = exact_log2(type2aelembytes(T_OBJECT));
int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
if (count > 0 && elements[0]->is_Con() &&
(count == 1 ||
(count == 2 && elements[1]->Opcode() == Op_LShiftX &&
elements[1]->in(2) == phase->intcon(shift)))) {
ciObjArray* array = base_type->const_oop()->as_obj_array();
// Fetch the box object cache[0] at the base of the array and get its value
ciInstance* box = array->obj_at(0)->as_instance();
ciInstanceKlass* ik = box->klass()->as_instance_klass();
assert(ik->is_box_klass(), "sanity");
assert(ik->nof_nonstatic_fields() == 1, "change following code");
if (ik->nof_nonstatic_fields() == 1) {
// This should be true nonstatic_field_at requires calling
// nof_nonstatic_fields so check it anyway
ciConstant c = box->field_value(ik->nonstatic_field_at(0));
BasicType bt = c.basic_type();
// Only integer types have boxing cache.
assert(bt == T_BOOLEAN || bt == T_CHAR ||
bt == T_BYTE || bt == T_SHORT ||
bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
if (cache_low != (int)cache_low) {
return NULL; // should not happen since cache is array indexed by value
}
jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
if (offset != (int)offset) {
return NULL; // should not happen since cache is array indexed by value
}
// Add up all the offsets making of the address of the load
Node* result = elements[0];
for (int i = 1; i < count; i++) {
result = phase->transform(new AddXNode(result, elements[i]));
}
// Remove the constant offset from the address and then
result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
// remove the scaling of the offset to recover the original index.
if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
// Peel the shift off directly but wrap it in a dummy node
// since Ideal can't return existing nodes
result = new RShiftXNode(result->in(1), phase->intcon(0));
} else if (result->is_Add() && result->in(2)->is_Con() &&
result->in(1)->Opcode() == Op_LShiftX &&
result->in(1)->in(2) == phase->intcon(shift)) {
// We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
// but for boxing cache access we know that X<<Z will not overflow
// (there is range check) so we do this optimizatrion by hand here.
Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
} else {
result = new RShiftXNode(result, phase->intcon(shift));
}
#ifdef _LP64
if (bt != T_LONG) {
result = new ConvL2INode(phase->transform(result));
}
#else
if (bt == T_LONG) {
result = new ConvI2LNode(phase->transform(result));
}
#endif
// Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
// Need to preserve unboxing load type if it is unsigned.
switch(this->Opcode()) {
case Op_LoadUB:
result = new AndINode(phase->transform(result), phase->intcon(0xFF));
break;
case Op_LoadUS:
result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
break;
}
return result;
}
}
}
}
}
return NULL;
}
static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
Node* region = phi->in(0);
if (region == NULL) {
return false; // Wait stable graph
}
uint cnt = phi->req();
for (uint i = 1; i < cnt; i++) {
Node* rc = region->in(i);
if (rc == NULL || phase->type(rc) == Type::TOP)
return false; // Wait stable graph
Node* in = phi->in(i);
if (in == NULL || phase->type(in) == Type::TOP)
return false; // Wait stable graph
}
return true;
}
//------------------------------split_through_phi------------------------------
// Split instance or boxed field load through Phi.
Node *LoadNode::split_through_phi(PhaseGVN *phase) {
Node* mem = in(Memory);
Node* address = in(Address);
const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
assert((t_oop != NULL) &&
(t_oop->is_known_instance_field() ||
t_oop->is_ptr_to_boxed_value()), "invalide conditions");
Compile* C = phase->C;
intptr_t ignore = 0;
Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
bool base_is_phi = (base != NULL) && base->is_Phi();
bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
(base != NULL) && (base == address->in(AddPNode::Base)) &&
phase->type(base)->higher_equal(TypePtr::NOTNULL);
if (!((mem->is_Phi() || base_is_phi) &&
(load_boxed_values || t_oop->is_known_instance_field()))) {
return NULL; // memory is not Phi
}
if (mem->is_Phi()) {
if (!stable_phi(mem->as_Phi(), phase)) {
return NULL; // Wait stable graph
}
uint cnt = mem->req();
// Check for loop invariant memory.
if (cnt == 3) {
for (uint i = 1; i < cnt; i++) {
Node* in = mem->in(i);
Node* m = optimize_memory_chain(in, t_oop, this, phase);
if (m == mem) {
set_req(Memory, mem->in(cnt - i));
return this; // made change
}
}
}
}
if (base_is_phi) {
if (!stable_phi(base->as_Phi(), phase)) {
return NULL; // Wait stable graph
}
uint cnt = base->req();
// Check for loop invariant memory.
if (cnt == 3) {
for (uint i = 1; i < cnt; i++) {
if (base->in(i) == base) {
return NULL; // Wait stable graph
}
}
}
}
bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
// Split through Phi (see original code in loopopts.cpp).
assert(C->have_alias_type(t_oop), "instance should have alias type");
// Do nothing here if Identity will find a value
// (to avoid infinite chain of value phis generation).
if (!phase->eqv(this, this->Identity(phase)))
return NULL;
// Select Region to split through.
Node* region;
if (!base_is_phi) {
assert(mem->is_Phi(), "sanity");
region = mem->in(0);
// Skip if the region dominates some control edge of the address.
if (!MemNode::all_controls_dominate(address, region))
return NULL;
} else if (!mem->is_Phi()) {
assert(base_is_phi, "sanity");
region = base->in(0);
// Skip if the region dominates some control edge of the memory.
if (!MemNode::all_controls_dominate(mem, region))
return NULL;
} else if (base->in(0) != mem->in(0)) {
assert(base_is_phi && mem->is_Phi(), "sanity");
if (MemNode::all_controls_dominate(mem, base->in(0))) {
region = base->in(0);
} else if (MemNode::all_controls_dominate(address, mem->in(0))) {
region = mem->in(0);
} else {
return NULL; // complex graph
}
} else {
assert(base->in(0) == mem->in(0), "sanity");
region = mem->in(0);
}
const Type* this_type = this->bottom_type();
int this_index = C->get_alias_index(t_oop);
int this_offset = t_oop->offset();
int this_iid = t_oop->instance_id();
if (!t_oop->is_known_instance() && load_boxed_values) {
// Use _idx of address base for boxed values.
this_iid = base->_idx;
}
PhaseIterGVN* igvn = phase->is_IterGVN();
Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
for (uint i = 1; i < region->req(); i++) {
Node* x;
Node* the_clone = NULL;
if (region->in(i) == C->top()) {
x = C->top(); // Dead path? Use a dead data op
} else {
x = this->clone(); // Else clone up the data op
the_clone = x; // Remember for possible deletion.
// Alter data node to use pre-phi inputs
if (this->in(0) == region) {
x->set_req(0, region->in(i));
} else {
x->set_req(0, NULL);
}
if (mem->is_Phi() && (mem->in(0) == region)) {
x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
}
if (address->is_Phi() && address->in(0) == region) {
x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
}
if (base_is_phi && (base->in(0) == region)) {
Node* base_x = base->in(i); // Clone address for loads from boxed objects.
Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
x->set_req(Address, adr_x);
}
}
// Check for a 'win' on some paths
const Type *t = x->Value(igvn);
bool singleton = t->singleton();
// See comments in PhaseIdealLoop::split_thru_phi().
if (singleton && t == Type::TOP) {
singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
}
if (singleton) {
x = igvn->makecon(t);
} else {
// We now call Identity to try to simplify the cloned node.
// Note that some Identity methods call phase->type(this).
// Make sure that the type array is big enough for
// our new node, even though we may throw the node away.
// (This tweaking with igvn only works because x is a new node.)
igvn->set_type(x, t);
// If x is a TypeNode, capture any more-precise type permanently into Node
// otherwise it will be not updated during igvn->transform since
// igvn->type(x) is set to x->Value() already.
x->raise_bottom_type(t);
Node *y = x->Identity(igvn);
if (y != x) {
x = y;
} else {
y = igvn->hash_find_insert(x);
if (y) {
x = y;
} else {
// Else x is a new node we are keeping
// We do not need register_new_node_with_optimizer
// because set_type has already been called.
igvn->_worklist.push(x);
}
}
}
if (x != the_clone && the_clone != NULL) {
igvn->remove_dead_node(the_clone);
}
phi->set_req(i, x);
}
// Record Phi
igvn->register_new_node_with_optimizer(phi);
return phi;
}
//------------------------------Ideal------------------------------------------
// If the load is from Field memory and the pointer is non-null, it might be possible to
// zero out the control input.
// If the offset is constant and the base is an object allocation,
// try to hook me up to the exact initializing store.
Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
Node* p = MemNode::Ideal_common(phase, can_reshape);
if (p) return (p == NodeSentinel) ? NULL : p;
Node* ctrl = in(MemNode::Control);
Node* address = in(MemNode::Address);
bool progress = false;
// Skip up past a SafePoint control. Cannot do this for Stores because
// pointer stores & cardmarks must stay on the same side of a SafePoint.
if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
ctrl = ctrl->in(0);
set_req(MemNode::Control,ctrl);
progress = true;
}
intptr_t ignore = 0;
Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
if (base != NULL
&& phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
// Check for useless control edge in some common special cases
if (in(MemNode::Control) != NULL
&& can_remove_control()
&& phase->type(base)->higher_equal(TypePtr::NOTNULL)
&& all_controls_dominate(base, phase->C->start())) {
// A method-invariant, non-null address (constant or 'this' argument).
set_req(MemNode::Control, NULL);
progress = true;
}
}
Node* mem = in(MemNode::Memory);
const TypePtr *addr_t = phase->type(address)->isa_ptr();
if (can_reshape && (addr_t != NULL)) {
// try to optimize our memory input
Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
if (opt_mem != mem) {
set_req(MemNode::Memory, opt_mem);
if (phase->type( opt_mem ) == Type::TOP) return NULL;
return this;
}
const TypeOopPtr *t_oop = addr_t->isa_oopptr();
if ((t_oop != NULL) &&
(t_oop->is_known_instance_field() ||
t_oop->is_ptr_to_boxed_value())) {
PhaseIterGVN *igvn = phase->is_IterGVN();
if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
// Delay this transformation until memory Phi is processed.
phase->is_IterGVN()->_worklist.push(this);
return NULL;
}
// Split instance field load through Phi.
Node* result = split_through_phi(phase);
if (result != NULL) return result;
if (t_oop->is_ptr_to_boxed_value()) {
Node* result = eliminate_autobox(phase);
if (result != NULL) return result;
}
}
}
// Is there a dominating load that loads the same value? Leave
// anything that is not a load of a field/array element (like
// barriers etc.) alone
if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
Node *use = mem->fast_out(i);
if (use != this &&
use->Opcode() == Opcode() &&
use->in(0) != NULL &&
use->in(0) != in(0) &&
use->in(Address) == in(Address)) {
Node* ctl = in(0);
for (int i = 0; i < 10 && ctl != NULL; i++) {
ctl = IfNode::up_one_dom(ctl);
if (ctl == use->in(0)) {
set_req(0, use->in(0));
return this;
}
}
}
}
}
// Check for prior store with a different base or offset; make Load
// independent. Skip through any number of them. Bail out if the stores
// are in an endless dead cycle and report no progress. This is a key
// transform for Reflection. However, if after skipping through the Stores
// we can't then fold up against a prior store do NOT do the transform as
// this amounts to using the 'Oracle' model of aliasing. It leaves the same
// array memory alive twice: once for the hoisted Load and again after the
// bypassed Store. This situation only works if EVERYBODY who does
// anti-dependence work knows how to bypass. I.e. we need all
// anti-dependence checks to ask the same Oracle. Right now, that Oracle is
// the alias index stuff. So instead, peek through Stores and IFF we can
// fold up, do so.
Node* prev_mem = find_previous_store(phase);
if (prev_mem != NULL) {
Node* value = can_see_arraycopy_value(prev_mem, phase);
if (value != NULL) {
return value;
}
}
// Steps (a), (b): Walk past independent stores to find an exact match.
if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
// (c) See if we can fold up on the spot, but don't fold up here.
// Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
// just return a prior value, which is done by Identity calls.
if (can_see_stored_value(prev_mem, phase)) {
// Make ready for step (d):
set_req(MemNode::Memory, prev_mem);
return this;
}
}
return progress ? this : NULL;
}
// Helper to recognize certain Klass fields which are invariant across
// some group of array types (e.g., int[] or all T[] where T < Object).
const Type*
LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
ciKlass* klass) const {
if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
// The field is Klass::_modifier_flags. Return its (constant) value.
// (Folds up the 2nd indirection in aClassConstant.getModifiers().)
assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
return TypeInt::make(klass->modifier_flags());
}
if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
// The field is Klass::_access_flags. Return its (constant) value.
// (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
return TypeInt::make(klass->access_flags());
}
if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
// The field is Klass::_layout_helper. Return its constant value if known.
assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
return TypeInt::make(klass->layout_helper());
}
// No match.
return NULL;
}
//------------------------------Value-----------------------------------------
const Type* LoadNode::Value(PhaseGVN* phase) const {
// Either input is TOP ==> the result is TOP
Node* mem = in(MemNode::Memory);
const Type *t1 = phase->type(mem);
if (t1 == Type::TOP) return Type::TOP;
Node* adr = in(MemNode::Address);
const TypePtr* tp = phase->type(adr)->isa_ptr();
if (tp == NULL || tp->empty()) return Type::TOP;
int off = tp->offset();
assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
Compile* C = phase->C;
// Try to guess loaded type from pointer type
if (tp->isa_aryptr()) {
const TypeAryPtr* ary = tp->is_aryptr();
const Type* t = ary->elem();
// Determine whether the reference is beyond the header or not, by comparing
// the offset against the offset of the start of the array's data.
// Different array types begin at slightly different offsets (12 vs. 16).
// We choose T_BYTE as an example base type that is least restrictive
// as to alignment, which will therefore produce the smallest
// possible base offset.
const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
// Try to constant-fold a stable array element.
if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
// Make sure the reference is not into the header and the offset is constant
ciObject* aobj = ary->const_oop();
if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
stable_dimension,
memory_type(), is_unsigned());
if (con_type != NULL) {
return con_type;
}
}
}
// Don't do this for integer types. There is only potential profit if
// the element type t is lower than _type; that is, for int types, if _type is
// more restrictive than t. This only happens here if one is short and the other
// char (both 16 bits), and in those cases we've made an intentional decision
// to use one kind of load over the other. See AndINode::Ideal and 4965907.
// Also, do not try to narrow the type for a LoadKlass, regardless of offset.
//
// Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
// where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
// copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
// subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
// it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
// In fact, that could have been the original type of p1, and p1 could have
// had an original form like p1:(AddP x x (LShiftL quux 3)), where the
// expression (LShiftL quux 3) independently optimized to the constant 8.
if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
&& (_type->isa_vect() == NULL)
&& Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
// t might actually be lower than _type, if _type is a unique
// concrete subclass of abstract class t.
if (off_beyond_header) { // is the offset beyond the header?
const Type* jt = t->join_speculative(_type);
// In any case, do not allow the join, per se, to empty out the type.
if (jt->empty() && !t->empty()) {
// This can happen if a interface-typed array narrows to a class type.
jt = _type;
}
#ifdef ASSERT
if (phase->C->eliminate_boxing() && adr->is_AddP()) {
// The pointers in the autobox arrays are always non-null
Node* base = adr->in(AddPNode::Base);
if ((base != NULL) && base->is_DecodeN()) {
// Get LoadN node which loads IntegerCache.cache field
base = base->in(1);
}
if ((base != NULL) && base->is_Con()) {
const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
if ((base_type != NULL) && base_type->is_autobox_cache()) {
// It could be narrow oop
assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
}
}
}
#endif
return jt;
}
}
} else if (tp->base() == Type::InstPtr) {
assert( off != Type::OffsetBot ||
// arrays can be cast to Objects
tp->is_oopptr()->klass()->is_java_lang_Object() ||
// unsafe field access may not have a constant offset
C->has_unsafe_access(),
"Field accesses must be precise" );
// For oop loads, we expect the _type to be precise.
// Optimize loads from constant fields.
const TypeInstPtr* tinst = tp->is_instptr();
ciObject* const_oop = tinst->const_oop();
if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
if (con_type != NULL) {
return con_type;
}
}
} else if (tp->base() == Type::KlassPtr) {
assert( off != Type::OffsetBot ||
// arrays can be cast to Objects
tp->is_klassptr()->klass()->is_java_lang_Object() ||
// also allow array-loading from the primary supertype
// array during subtype checks
Opcode() == Op_LoadKlass,
"Field accesses must be precise" );
// For klass/static loads, we expect the _type to be precise
} else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
/* With mirrors being an indirect in the Klass*
* the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
* The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
*
* So check the type and klass of the node before the LoadP.
*/
Node* adr2 = adr->in(MemNode::Address);
const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
if (tkls != NULL && !StressReflectiveCode) {
ciKlass* klass = tkls->klass();
if (klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
return TypeInstPtr::make(klass->java_mirror());
}
}
}
const TypeKlassPtr *tkls = tp->isa_klassptr();
if (tkls != NULL && !StressReflectiveCode) {
ciKlass* klass = tkls->klass();
if (klass->is_loaded() && tkls->klass_is_exact()) {
// We are loading a field from a Klass metaobject whose identity
// is known at compile time (the type is "exact" or "precise").
// Check for fields we know are maintained as constants by the VM.
if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
// The field is Klass::_super_check_offset. Return its (constant) value.
// (Folds up type checking code.)
assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
return TypeInt::make(klass->super_check_offset());
}
// Compute index into primary_supers array
juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
// Check for overflowing; use unsigned compare to handle the negative case.
if( depth < ciKlass::primary_super_limit() ) {
// The field is an element of Klass::_primary_supers. Return its (constant) value.
// (Folds up type checking code.)
assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
ciKlass *ss = klass->super_of_depth(depth);
return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
}
const Type* aift = load_array_final_field(tkls, klass);
if (aift != NULL) return aift;
}
// We can still check if we are loading from the primary_supers array at a
// shallow enough depth. Even though the klass is not exact, entries less
// than or equal to its super depth are correct.
if (klass->is_loaded() ) {
ciType *inner = klass;
while( inner->is_obj_array_klass() )
inner = inner->as_obj_array_klass()->base_element_type();
if( inner->is_instance_klass() &&
!inner->as_instance_klass()->flags().is_interface() ) {
// Compute index into primary_supers array
juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
// Check for overflowing; use unsigned compare to handle the negative case.
if( depth < ciKlass::primary_super_limit() &&
depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
// The field is an element of Klass::_primary_supers. Return its (constant) value.
// (Folds up type checking code.)
assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
ciKlass *ss = klass->super_of_depth(depth);
return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
}
}
}
// If the type is enough to determine that the thing is not an array,
// we can give the layout_helper a positive interval type.
// This will help short-circuit some reflective code.
if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
&& !klass->is_array_klass() // not directly typed as an array
&& !klass->is_interface() // specifically not Serializable & Cloneable
&& !klass->is_java_lang_Object() // not the supertype of all T[]
) {
// Note: When interfaces are reliable, we can narrow the interface
// test to (klass != Serializable && klass != Cloneable).
assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
// The key property of this type is that it folds up tests
// for array-ness, since it proves that the layout_helper is positive.
// Thus, a generic value like the basic object layout helper works fine.
return TypeInt::make(min_size, max_jint, Type::WidenMin);
}
}
// If we are loading from a freshly-allocated object, produce a zero,
// if the load is provably beyond the header of the object.
// (Also allow a variable load from a fresh array to produce zero.)
const TypeOopPtr *tinst = tp->isa_oopptr();
bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
if (ReduceFieldZeroing || is_instance || is_boxed_value) {
Node* value = can_see_stored_value(mem,phase);
if (value != NULL && value->is_Con()) {
assert(value->bottom_type()->higher_equal(_type),"sanity");
return value->bottom_type();
}
}
if (is_instance) {
// If we have an instance type and our memory input is the
// programs's initial memory state, there is no matching store,
// so just return a zero of the appropriate type
Node *mem = in(MemNode::Memory);
if (mem->is_Parm() && mem->in(0)->is_Start()) {
assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
return Type::get_zero_type(_type->basic_type());
}
}
return _type;
}
//------------------------------match_edge-------------------------------------
// Do we Match on this edge index or not? Match only the address.
uint LoadNode::match_edge(uint idx) const {
return idx == MemNode::Address;
}
//--------------------------LoadBNode::Ideal--------------------------------------
//
// If the previous store is to the same address as this load,
// and the value stored was larger than a byte, replace this load
// with the value stored truncated to a byte. If no truncation is
// needed, the replacement is done in LoadNode::Identity().
//
Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
Node* mem = in(MemNode::Memory);
Node* value = can_see_stored_value(mem,phase);
if( value && !phase->type(value)->higher_equal( _type ) ) {
Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
return new RShiftINode(result, phase->intcon(24));
}
// Identity call will handle the case where truncation is not needed.
return LoadNode::Ideal(phase, can_reshape);
}
const Type* LoadBNode::Value(PhaseGVN* phase) const {
Node* mem = in(MemNode::Memory);
Node* value = can_see_stored_value(mem,phase);
if (value != NULL && value->is_Con() &&
!value->bottom_type()->higher_equal(_type)) {
// If the input to the store does not fit with the load's result type,
// it must be truncated. We can't delay until Ideal call since
// a singleton Value is needed for split_thru_phi optimization.
int con = value->get_int();
return TypeInt::make((con << 24) >> 24);
}
return LoadNode::Value(phase);
}
//--------------------------LoadUBNode::Ideal-------------------------------------
//
// If the previous store is to the same address as this load,
// and the value stored was larger than a byte, replace this load
// with the value stored truncated to a byte. If no truncation is
// needed, the replacement is done in LoadNode::Identity().
//
Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
Node* mem = in(MemNode::Memory);
Node* value = can_see_stored_value(mem, phase);
if (value && !phase->type(value)->higher_equal(_type))
return new AndINode(value, phase->intcon(0xFF));
// Identity call will handle the case where truncation is not needed.
return LoadNode::Ideal(phase, can_reshape);
}
const Type* LoadUBNode::Value(PhaseGVN* phase) const {
Node* mem = in(MemNode::Memory);
Node* value = can_see_stored_value(mem,phase);
if (value != NULL && value->is_Con() &&
!value->bottom_type()->higher_equal(_type)) {
// If the input to the store does not fit with the load's result type,
// it must be truncated. We can't delay until Ideal call since
// a singleton Value is needed for split_thru_phi optimization.
int con = value->get_int();
return TypeInt::make(con & 0xFF);
}
return LoadNode::Value(phase);
}
//--------------------------LoadUSNode::Ideal-------------------------------------
//
// If the previous store is to the same address as this load,
// and the value stored was larger than a char, replace this load
// with the value stored truncated to a char. If no truncation is
// needed, the replacement is done in LoadNode::Identity().
//
Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
Node* mem = in(MemNode::Memory);
Node* value = can_see_stored_value(mem,phase);
if( value && !phase->type(value)->higher_equal( _type ) )
return new AndINode(value,phase->intcon(0xFFFF));
// Identity call will handle the case where truncation is not needed.
return LoadNode::Ideal(phase, can_reshape);
}
const Type* LoadUSNode::Value(PhaseGVN* phase) const {
Node* mem = in(MemNode::Memory);
Node* value = can_see_stored_value(mem,phase);
if (value != NULL && value->is_Con() &&
!value->bottom_type()->higher_equal(_type)) {
// If the input to the store does not fit with the load's result type,
// it must be truncated. We can't delay until Ideal call since
// a singleton Value is needed for split_thru_phi optimization.
int con = value->get_int();
return TypeInt::make(con & 0xFFFF);
}
return LoadNode::Value(phase);
}
//--------------------------LoadSNode::Ideal--------------------------------------
//
// If the previous store is to the same address as this load,
// and the value stored was larger than a short, replace this load
// with the value stored truncated to a short. If no truncation is
// needed, the replacement is done in LoadNode::Identity().
//
Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
Node* mem = in(MemNode::Memory);
Node* value = can_see_stored_value(mem,phase);
if( value && !phase->type(value)->higher_equal( _type ) ) {
Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
return new RShiftINode(result, phase->intcon(16));
}
// Identity call will handle the case where truncation is not needed.
return LoadNode::Ideal(phase, can_reshape);
}
const Type* LoadSNode::Value(PhaseGVN* phase) const {
Node* mem = in(MemNode::Memory);
Node* value = can_see_stored_value(mem,phase);
if (value != NULL && value->is_Con() &&
!value->bottom_type()->higher_equal(_type)) {
// If the input to the store does not fit with the load's result type,
// it must be truncated. We can't delay until Ideal call since
// a singleton Value is needed for split_thru_phi optimization.
int con = value->get_int();
return TypeInt::make((con << 16) >> 16);
}
return LoadNode::Value(phase);
}
//=============================================================================
//----------------------------LoadKlassNode::make------------------------------
// Polymorphic factory method:
Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
// sanity check the alias category against the created node type
const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
assert(adr_type != NULL, "expecting TypeKlassPtr");
#ifdef _LP64
if (adr_type->is_ptr_to_narrowklass()) {
assert(UseCompressedClassPointers, "no compressed klasses");
Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
}
#endif
assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
}
//------------------------------Value------------------------------------------
const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
return klass_value_common(phase);
}
// In most cases, LoadKlassNode does not have the control input set. If the control
// input is set, it must not be removed (by LoadNode::Ideal()).
bool LoadKlassNode::can_remove_control() const {
return false;
}
const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
// Either input is TOP ==> the result is TOP
const Type *t1 = phase->type( in(MemNode::Memory) );
if (t1 == Type::TOP) return Type::TOP;
Node *adr = in(MemNode::Address);
const Type *t2 = phase->type( adr );
if (t2 == Type::TOP) return Type::TOP;
const TypePtr *tp = t2->is_ptr();
if (TypePtr::above_centerline(tp->ptr()) ||
tp->ptr() == TypePtr::Null) return Type::TOP;
// Return a more precise klass, if possible
const TypeInstPtr *tinst = tp->isa_instptr();
if (tinst != NULL) {
ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
int offset = tinst->offset();
if (ik == phase->C->env()->Class_klass()
&& (offset == java_lang_Class::klass_offset_in_bytes() ||
offset == java_lang_Class::array_klass_offset_in_bytes())) {
// We are loading a special hidden field from a Class mirror object,
// the field which points to the VM's Klass metaobject.
ciType* t = tinst->java_mirror_type();
// java_mirror_type returns non-null for compile-time Class constants.
if (t != NULL) {
// constant oop => constant klass
if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
if (t->is_void()) {
// We cannot create a void array. Since void is a primitive type return null
// klass. Users of this result need to do a null check on the returned klass.
return TypePtr::NULL_PTR;
}
return TypeKlassPtr::make(ciArrayKlass::make(t));
}
if (!t->is_klass()) {
// a primitive Class (e.g., int.class) has NULL for a klass field
return TypePtr::NULL_PTR;
}
// (Folds up the 1st indirection in aClassConstant.getModifiers().)
return TypeKlassPtr::make(t->as_klass());
}
// non-constant mirror, so we can't tell what's going on
}
if( !ik->is_loaded() )
return _type; // Bail out if not loaded
if (offset == oopDesc::klass_offset_in_bytes()) {
if (tinst->klass_is_exact()) {
return TypeKlassPtr::make(ik);
}
// See if we can become precise: no subklasses and no interface
// (Note: We need to support verified interfaces.)
if (!ik->is_interface() && !ik->has_subklass()) {
//assert(!UseExactTypes, "this code should be useless with exact types");
// Add a dependence; if any subclass added we need to recompile
if (!ik->is_final()) {
// %%% should use stronger assert_unique_concrete_subtype instead
phase->C->dependencies()->assert_leaf_type(ik);
}
// Return precise klass
return TypeKlassPtr::make(ik);
}
// Return root of possible klass
return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
}
}
// Check for loading klass from an array
const TypeAryPtr *tary = tp->isa_aryptr();
if( tary != NULL ) {
ciKlass *tary_klass = tary->klass();
if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
&& tary->offset() == oopDesc::klass_offset_in_bytes()) {
if (tary->klass_is_exact()) {
return TypeKlassPtr::make(tary_klass);
}
ciArrayKlass *ak = tary->klass()->as_array_klass();
// If the klass is an object array, we defer the question to the
// array component klass.
if( ak->is_obj_array_klass() ) {
assert( ak->is_loaded(), "" );
ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
if( base_k->is_loaded() && base_k->is_instance_klass() ) {
ciInstanceKlass* ik = base_k->as_instance_klass();
// See if we can become precise: no subklasses and no interface
if (!ik->is_interface() && !ik->has_subklass()) {
//assert(!UseExactTypes, "this code should be useless with exact types");
// Add a dependence; if any subclass added we need to recompile
if (!ik->is_final()) {
phase->C->dependencies()->assert_leaf_type(ik);
}
// Return precise array klass
return TypeKlassPtr::make(ak);
}
}
return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
} else { // Found a type-array?
//assert(!UseExactTypes, "this code should be useless with exact types");
assert( ak->is_type_array_klass(), "" );
return TypeKlassPtr::make(ak); // These are always precise
}
}
}
// Check for loading klass from an array klass
const TypeKlassPtr *tkls = tp->isa_klassptr();
if (tkls != NULL && !StressReflectiveCode) {
ciKlass* klass = tkls->klass();
if( !klass->is_loaded() )
return _type; // Bail out if not loaded
if( klass->is_obj_array_klass() &&
tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
ciKlass* elem = klass->as_obj_array_klass()->element_klass();
// // Always returning precise element type is incorrect,
// // e.g., element type could be object and array may contain strings
// return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
// The array's TypeKlassPtr was declared 'precise' or 'not precise'
// according to the element type's subclassing.
return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
}
if( klass->is_instance_klass() && tkls->klass_is_exact() &&
tkls->offset() == in_bytes(Klass::super_offset())) {
ciKlass* sup = klass->as_instance_klass()->super();
// The field is Klass::_super. Return its (constant) value.
// (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
}
}
// Bailout case
return LoadNode::Value(phase);
}
//------------------------------Identity---------------------------------------
// To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
// Also feed through the klass in Allocate(...klass...)._klass.
Node* LoadKlassNode::Identity(PhaseGVN* phase) {
return klass_identity_common(phase);
}
Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
Node* x = LoadNode::Identity(phase);
if (x != this) return x;
// Take apart the address into an oop and and offset.
// Return 'this' if we cannot.
Node* adr = in(MemNode::Address);
intptr_t offset = 0;
Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
if (base == NULL) return this;
const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
if (toop == NULL) return this;
// We can fetch the klass directly through an AllocateNode.
// This works even if the klass is not constant (clone or newArray).
if (offset == oopDesc::klass_offset_in_bytes()) {
Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
if (allocated_klass != NULL) {
return allocated_klass;
}
}
// Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
// See inline_native_Class_query for occurrences of these patterns.
// Java Example: x.getClass().isAssignableFrom(y)
//
// This improves reflective code, often making the Class
// mirror go completely dead. (Current exception: Class
// mirrors may appear in debug info, but we could clean them out by
// introducing a new debug info operator for Klass.java_mirror).
//
// If the code pattern requires a barrier for
// mirror = ((OopHandle)mirror)->resolve();
// this won't match.
if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
&& offset == java_lang_Class::klass_offset_in_bytes()) {
if (base->is_Load()) {
Node* base2 = base->in(MemNode::Address);
if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
Node* adr2 = base2->in(MemNode::Address);
const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
if (tkls != NULL && !tkls->empty()
&& (tkls->klass()->is_instance_klass() ||
tkls->klass()->is_array_klass())
&& adr2->is_AddP()
) {
int mirror_field = in_bytes(Klass::java_mirror_offset());
if (tkls->offset() == mirror_field) {
return adr2->in(AddPNode::Base);
}
}
}
}
}
return this;
}
//------------------------------Value------------------------------------------
const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
const Type *t = klass_value_common(phase);
if (t == Type::TOP)
return t;
return t->make_narrowklass();
}
//------------------------------Identity---------------------------------------
// To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
// Also feed through the klass in Allocate(...klass...)._klass.
Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
Node *x = klass_identity_common(phase);
const Type *t = phase->type( x );
if( t == Type::TOP ) return x;
if( t->isa_narrowklass()) return x;
assert (!t->isa_narrowoop(), "no narrow oop here");
return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
}
//------------------------------Value-----------------------------------------
const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
// Either input is TOP ==> the result is TOP
const Type *t1 = phase->type( in(MemNode::Memory) );
if( t1 == Type::TOP ) return Type::TOP;
Node *adr = in(MemNode::Address);
const Type *t2 = phase->type( adr );
if( t2 == Type::TOP ) return Type::TOP;
const TypePtr *tp = t2->is_ptr();
if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
const TypeAryPtr *tap = tp->isa_aryptr();
if( !tap ) return _type;
return tap->size();
}
//-------------------------------Ideal---------------------------------------
// Feed through the length in AllocateArray(...length...)._length.
Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
Node* p = MemNode::Ideal_common(phase, can_reshape);
if (p) return (p == NodeSentinel) ? NULL : p;
// Take apart the address into an oop and and offset.
// Return 'this' if we cannot.
Node* adr = in(MemNode::Address);
intptr_t offset = 0;
Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
if (base == NULL) return NULL;
const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
if (tary == NULL) return NULL;
// We can fetch the length directly through an AllocateArrayNode.
// This works even if the length is not constant (clone or newArray).
if (offset == arrayOopDesc::length_offset_in_bytes()) {
AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
if (alloc != NULL) {
Node* allocated_length = alloc->Ideal_length();
Node* len = alloc->make_ideal_length(tary, phase);
if (allocated_length != len) {
// New CastII improves on this.
return len;
}
}
}
return NULL;
}
//------------------------------Identity---------------------------------------
// Feed through the length in AllocateArray(...length...)._length.
Node* LoadRangeNode::Identity(PhaseGVN* phase) {
Node* x = LoadINode::Identity(phase);
if (x != this) return x;
// Take apart the address into an oop and and offset.
// Return 'this' if we cannot.
Node* adr = in(MemNode::Address);
intptr_t offset = 0;
Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
if (base == NULL) return this;
const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
if (tary == NULL) return this;
// We can fetch the length directly through an AllocateArrayNode.
// This works even if the length is not constant (clone or newArray).
if (offset == arrayOopDesc::length_offset_in_bytes()) {
AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
if (alloc != NULL) {
Node* allocated_length = alloc->Ideal_length();
// Do not allow make_ideal_length to allocate a CastII node.
Node* len = alloc->make_ideal_length(tary, phase, false);
if (allocated_length == len) {
// Return allocated_length only if it would not be improved by a CastII.
return allocated_length;
}
}
}
return this;
}
//=============================================================================
//---------------------------StoreNode::make-----------------------------------
// Polymorphic factory method:
StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
assert((mo == unordered || mo == release), "unexpected");
Compile* C = gvn.C;
assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
ctl != NULL, "raw memory operations should have control edge");
switch (bt) {
case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
case T_CHAR:
case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
case T_METADATA:
case T_ADDRESS:
case T_OBJECT:
#ifdef _LP64
if (adr->bottom_type()->is_ptr_to_narrowoop()) {
val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
} else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
(UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
adr->bottom_type()->isa_rawptr())) {
val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
}
#endif
{
return new StorePNode(ctl, mem, adr, adr_type, val, mo);
}
default:
ShouldNotReachHere();
return (StoreNode*)NULL;
}
}
StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
bool require_atomic = true;
return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
}
StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
bool require_atomic = true;
return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
}
//--------------------------bottom_type----------------------------------------
const Type *StoreNode::bottom_type() const {
return Type::MEMORY;
}
//------------------------------hash-------------------------------------------
uint StoreNode::hash() const {
// unroll addition of interesting fields
//return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
// Since they are not commoned, do not hash them:
return NO_HASH;
}
//------------------------------Ideal------------------------------------------
// Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
// When a store immediately follows a relevant allocation/initialization,
// try to capture it into the initialization, or hoist it above.
Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
Node* p = MemNode::Ideal_common(phase, can_reshape);
if (p) return (p == NodeSentinel) ? NULL : p;
Node* mem = in(MemNode::Memory);
Node* address = in(MemNode::Address);
// Back-to-back stores to same address? Fold em up. Generally
// unsafe if I have intervening uses... Also disallowed for StoreCM
// since they must follow each StoreP operation. Redundant StoreCMs
// are eliminated just before matching in final_graph_reshape.
{
Node* st = mem;
// If Store 'st' has more than one use, we cannot fold 'st' away.
// For example, 'st' might be the final state at a conditional
// return. Or, 'st' might be used by some node which is live at
// the same time 'st' is live, which might be unschedulable. So,
// require exactly ONE user until such time as we clone 'mem' for
// each of 'mem's uses (thus making the exactly-1-user-rule hold
// true).
while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
// Looking at a dead closed cycle of memory?
assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
assert(Opcode() == st->Opcode() ||
st->Opcode() == Op_StoreVector ||
Opcode() == Op_StoreVector ||
phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
(Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
(Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
(is_mismatched_access() || st->as_Store()->is_mismatched_access()),
"no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
if (st->in(MemNode::Address)->eqv_uncast(address) &&
st->as_Store()->memory_size() <= this->memory_size()) {
Node* use = st->raw_out(0);
phase->igvn_rehash_node_delayed(use);
if (can_reshape) {
use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
} else {
// It's OK to do this in the parser, since DU info is always accurate,
// and the parser always refers to nodes via SafePointNode maps.
use->set_req(MemNode::Memory, st->in(MemNode::Memory));
}
return this;
}
st = st->in(MemNode::Memory);
}
}
// Capture an unaliased, unconditional, simple store into an initializer.
// Or, if it is independent of the allocation, hoist it above the allocation.
if (ReduceFieldZeroing && /*can_reshape &&*/
mem->is_Proj() && mem->in(0)->is_Initialize()) {
InitializeNode* init = mem->in(0)->as_Initialize();
intptr_t offset = init->can_capture_store(this, phase, can_reshape);
if (offset > 0) {
Node* moved = init->capture_store(this, offset, phase, can_reshape);
// If the InitializeNode captured me, it made a raw copy of me,
// and I need to disappear.
if (moved != NULL) {
// %%% hack to ensure that Ideal returns a new node:
mem = MergeMemNode::make(mem);
return mem; // fold me away
}
}
}
return NULL; // No further progress
}
//------------------------------Value-----------------------------------------
const Type* StoreNode::Value(PhaseGVN* phase) const {
// Either input is TOP ==> the result is TOP
const Type *t1 = phase->type( in(MemNode::Memory) );
if( t1 == Type::TOP ) return Type::TOP;
const Type *t2 = phase->type( in(MemNode::Address) );
if( t2 == Type::TOP ) return Type::TOP;
const Type *t3 = phase->type( in(MemNode::ValueIn) );
if( t3 == Type::TOP ) return Type::TOP;
return Type::MEMORY;
}
//------------------------------Identity---------------------------------------
// Remove redundant stores:
// Store(m, p, Load(m, p)) changes to m.
// Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
Node* StoreNode::Identity(PhaseGVN* phase) {
Node* mem = in(MemNode::Memory);
Node* adr = in(MemNode::Address);
Node* val = in(MemNode::ValueIn);
// Load then Store? Then the Store is useless
if (val->is_Load() &&
val->in(MemNode::Address)->eqv_uncast(adr) &&
val->in(MemNode::Memory )->eqv_uncast(mem) &&
val->as_Load()->store_Opcode() == Opcode()) {
return mem;
}
// Two stores in a row of the same value?
if (mem->is_Store() &&
mem->in(MemNode::Address)->eqv_uncast(adr) &&
mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
mem->Opcode() == Opcode()) {
return mem;
}
// Store of zero anywhere into a freshly-allocated object?
// Then the store is useless.
// (It must already have been captured by the InitializeNode.)
if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
// a newly allocated object is already all-zeroes everywhere
if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
return mem;
}
// the store may also apply to zero-bits in an earlier object
Node* prev_mem = find_previous_store(phase);
// Steps (a), (b): Walk past independent stores to find an exact match.
if (prev_mem != NULL) {
Node* prev_val = can_see_stored_value(prev_mem, phase);
if (prev_val != NULL && phase->eqv(prev_val, val)) {
// prev_val and val might differ by a cast; it would be good
// to keep the more informative of the two.
return mem;
}
}
}
return this;
}
//------------------------------match_edge-------------------------------------
// Do we Match on this edge index or not? Match only memory & value
uint StoreNode::match_edge(uint idx) const {
return idx == MemNode::Address || idx == MemNode::ValueIn;
}
//------------------------------cmp--------------------------------------------
// Do not common stores up together. They generally have to be split
// back up anyways, so do not bother.
uint StoreNode::cmp( const Node &n ) const {
return (&n == this); // Always fail except on self
}
//------------------------------Ideal_masked_input-----------------------------
// Check for a useless mask before a partial-word store
// (StoreB ... (AndI valIn conIa) )
// If (conIa & mask == mask) this simplifies to
// (StoreB ... (valIn) )
Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
Node *val = in(MemNode::ValueIn);
if( val->Opcode() == Op_AndI ) {
const TypeInt *t = phase->type( val->in(2) )->isa_int();
if( t && t->is_con() && (t->get_con() & mask) == mask ) {
set_req(MemNode::ValueIn, val->in(1));
return this;
}
}
return NULL;
}
//------------------------------Ideal_sign_extended_input----------------------
// Check for useless sign-extension before a partial-word store
// (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
// If (conIL == conIR && conIR <= num_bits) this simplifies to
// (StoreB ... (valIn) )
Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
Node *val = in(MemNode::ValueIn);
if( val->Opcode() == Op_RShiftI ) {
const TypeInt *t = phase->type( val->in(2) )->isa_int();
if( t && t->is_con() && (t->get_con() <= num_bits) ) {
Node *shl = val->in(1);
if( shl->Opcode() == Op_LShiftI ) {
const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
set_req(MemNode::ValueIn, shl->in(1));
return this;
}
}
}
}
return NULL;
}
//------------------------------value_never_loaded-----------------------------------
// Determine whether there are any possible loads of the value stored.
// For simplicity, we actually check if there are any loads from the
// address stored to, not just for loads of the value stored by this node.
//
bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
Node *adr = in(Address);
const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
if (adr_oop == NULL)
return false;
if (!adr_oop->is_known_instance_field())
return false; // if not a distinct instance, there may be aliases of the address
for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
Node *use = adr->fast_out(i);
if (use->is_Load() || use->is_LoadStore()) {
return false;
}
}
return true;
}
//=============================================================================
//------------------------------Ideal------------------------------------------
// If the store is from an AND mask that leaves the low bits untouched, then
// we can skip the AND operation. If the store is from a sign-extension
// (a left shift, then right shift) we can skip both.
Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
if( progress != NULL ) return progress;
progress = StoreNode::Ideal_sign_extended_input(phase, 24);
if( progress != NULL ) return progress;
// Finally check the default case
return StoreNode::Ideal(phase, can_reshape);
}
//=============================================================================
//------------------------------Ideal------------------------------------------
// If the store is from an AND mask that leaves the low bits untouched, then
// we can skip the AND operation
Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
if( progress != NULL ) return progress;
progress = StoreNode::Ideal_sign_extended_input(phase, 16);
if( progress != NULL ) return progress;
// Finally check the default case
return StoreNode::Ideal(phase, can_reshape);
}
//=============================================================================
//------------------------------Identity---------------------------------------
Node* StoreCMNode::Identity(PhaseGVN* phase) {
// No need to card mark when storing a null ptr
Node* my_store = in(MemNode::OopStore);
if (my_store->is_Store()) {
const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
if( t1 == TypePtr::NULL_PTR ) {
return in(MemNode::Memory);
}
}
return this;
}
//=============================================================================
//------------------------------Ideal---------------------------------------
Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
Node* progress = StoreNode::Ideal(phase, can_reshape);
if (progress != NULL) return progress;
Node* my_store = in(MemNode::OopStore);
if (my_store->is_MergeMem()) {
Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
set_req(MemNode::OopStore, mem);
return this;
}
return NULL;
}
//------------------------------Value-----------------------------------------
const Type* StoreCMNode::Value(PhaseGVN* phase) const {
// Either input is TOP ==> the result is TOP
const Type *t = phase->type( in(MemNode::Memory) );
if( t == Type::TOP ) return Type::TOP;
t = phase->type( in(MemNode::Address) );
if( t == Type::TOP ) return Type::TOP;
t = phase->type( in(MemNode::ValueIn) );
if( t == Type::TOP ) return Type::TOP;
// If extra input is TOP ==> the result is TOP
t = phase->type( in(MemNode::OopStore) );
if( t == Type::TOP ) return Type::TOP;
return StoreNode::Value( phase );
}
//=============================================================================
//----------------------------------SCMemProjNode------------------------------
const Type* SCMemProjNode::Value(PhaseGVN* phase) const
{
return bottom_type();
}
//=============================================================================
//----------------------------------LoadStoreNode------------------------------
LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
: Node(required),
_type(rt),
_adr_type(at)
{
init_req(MemNode::Control, c );
init_req(MemNode::Memory , mem);
init_req(MemNode::Address, adr);
init_req(MemNode::ValueIn, val);
init_class_id(Class_LoadStore);
}
uint LoadStoreNode::ideal_reg() const {
return _type->ideal_reg();
}
bool LoadStoreNode::result_not_used() const {
for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
Node *x = fast_out(i);
if (x->Opcode() == Op_SCMemProj) continue;
return false;
}
return true;
}
uint LoadStoreNode::size_of() const { return sizeof(*this); }
//=============================================================================
//----------------------------------LoadStoreConditionalNode--------------------
LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
init_req(ExpectedIn, ex );
}
//=============================================================================
//-------------------------------adr_type--------------------------------------
const TypePtr* ClearArrayNode::adr_type() const {
Node *adr = in(3);
if (adr == NULL) return NULL; // node is dead
return MemNode::calculate_adr_type(adr->bottom_type());
}
//------------------------------match_edge-------------------------------------
// Do we Match on this edge index or not? Do not match memory
uint ClearArrayNode::match_edge(uint idx) const {
return idx > 1;
}
//------------------------------Identity---------------------------------------
// Clearing a zero length array does nothing
Node* ClearArrayNode::Identity(PhaseGVN* phase) {
return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
}
//------------------------------Idealize---------------------------------------
// Clearing a short array is faster with stores
Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
// Already know this is a large node, do not try to ideal it
if (!IdealizeClearArrayNode || _is_large) return NULL;
const int unit = BytesPerLong;
const TypeX* t = phase->type(in(2))->isa_intptr_t();
if (!t) return NULL;
if (!t->is_con()) return NULL;
intptr_t raw_count = t->get_con();
intptr_t size = raw_count;
if (!Matcher::init_array_count_is_in_bytes) size *= unit;
// Clearing nothing uses the Identity call.
// Negative clears are possible on dead ClearArrays
// (see jck test stmt114.stmt11402.val).
if (size <= 0 || size % unit != 0) return NULL;
intptr_t count = size / unit;
// Length too long; communicate this to matchers and assemblers.
// Assemblers are responsible to produce fast hardware clears for it.
if (size > InitArrayShortSize) {
return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
}
Node *mem = in(1);
if( phase->type(mem)==Type::TOP ) return NULL;
Node *adr = in(3);
const Type* at = phase->type(adr);
if( at==Type::TOP ) return NULL;
const TypePtr* atp = at->isa_ptr();
// adjust atp to be the correct array element address type
if (atp == NULL) atp = TypePtr::BOTTOM;
else atp = atp->add_offset(Type::OffsetBot);
// Get base for derived pointer purposes
if( adr->Opcode() != Op_AddP ) Unimplemented();
Node *base = adr->in(1);
Node *zero = phase->makecon(TypeLong::ZERO);
Node *off = phase->MakeConX(BytesPerLong);
mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
count--;
while( count-- ) {
mem = phase->transform(mem);
adr = phase->transform(new AddPNode(base,adr,off));
mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
}
return mem;
}
//----------------------------step_through----------------------------------
// Return allocation input memory edge if it is different instance
// or itself if it is the one we are looking for.
bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
Node* n = *np;
assert(n->is_ClearArray(), "sanity");
intptr_t offset;
AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
// This method is called only before Allocate nodes are expanded
// during macro nodes expansion. Before that ClearArray nodes are
// only generated in PhaseMacroExpand::generate_arraycopy() (before
// Allocate nodes are expanded) which follows allocations.
assert(alloc != NULL, "should have allocation");
if (alloc->_idx == instance_id) {
// Can not bypass initialization of the instance we are looking for.
return false;
}
// Otherwise skip it.
InitializeNode* init = alloc->initialization();
if (init != NULL)
*np = init->in(TypeFunc::Memory);
else
*np = alloc->in(TypeFunc::Memory);
return true;
}
//----------------------------clear_memory-------------------------------------
// Generate code to initialize object storage to zero.
Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
intptr_t start_offset,
Node* end_offset,
PhaseGVN* phase) {
intptr_t offset = start_offset;
int unit = BytesPerLong;
if ((offset % unit) != 0) {
Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
adr = phase->transform(adr);
const TypePtr* atp = TypeRawPtr::BOTTOM;
mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
mem = phase->transform(mem);
offset += BytesPerInt;
}
assert((offset % unit) == 0, "");
// Initialize the remaining stuff, if any, with a ClearArray.
return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
}
Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
Node* start_offset,
Node* end_offset,
PhaseGVN* phase) {
if (start_offset == end_offset) {
// nothing to do
return mem;
}
int unit = BytesPerLong;
Node* zbase = start_offset;
Node* zend = end_offset;
// Scale to the unit required by the CPU:
if (!Matcher::init_array_count_is_in_bytes) {
Node* shift = phase->intcon(exact_log2(unit));
zbase = phase->transform(new URShiftXNode(zbase, shift) );
zend = phase->transform(new URShiftXNode(zend, shift) );
}
// Bulk clear double-words
Node* zsize = phase->transform(new SubXNode(zend, zbase) );
Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
return phase->transform(mem);
}
Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
intptr_t start_offset,
intptr_t end_offset,
PhaseGVN* phase) {
if (start_offset == end_offset) {
// nothing to do
return mem;
}
assert((end_offset % BytesPerInt) == 0, "odd end offset");
intptr_t done_offset = end_offset;
if ((done_offset % BytesPerLong) != 0) {
done_offset -= BytesPerInt;
}
if (done_offset > start_offset) {
mem = clear_memory(ctl, mem, dest,
start_offset, phase->MakeConX(done_offset), phase);
}
if (done_offset < end_offset) { // emit the final 32-bit store
Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
adr = phase->transform(adr);
const TypePtr* atp = TypeRawPtr::BOTTOM;
mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
mem = phase->transform(mem);
done_offset += BytesPerInt;
}
assert(done_offset == end_offset, "");
return mem;
}
//=============================================================================
MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
: MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
_adr_type(C->get_adr_type(alias_idx))
{
init_class_id(Class_MemBar);
Node* top = C->top();
init_req(TypeFunc::I_O,top);
init_req(TypeFunc::FramePtr,top);
init_req(TypeFunc::ReturnAdr,top);
if (precedent != NULL)
init_req(TypeFunc::Parms, precedent);
}
//------------------------------cmp--------------------------------------------
uint MemBarNode::hash() const { return NO_HASH; }
uint MemBarNode::cmp( const Node &n ) const {
return (&n == this); // Always fail except on self
}
//------------------------------make-------------------------------------------
MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
switch (opcode) {
case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
case Op_Initialize: return new InitializeNode(C, atp, pn);
case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
default: ShouldNotReachHere(); return NULL;
}
}
//------------------------------Ideal------------------------------------------
// Return a node which is more "ideal" than the current node. Strip out
// control copies
Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
if (remove_dead_region(phase, can_reshape)) return this;
// Don't bother trying to transform a dead node
if (in(0) && in(0)->is_top()) {
return NULL;
}
#if INCLUDE_ZGC
if (UseZGC) {
if (req() == (Precedent+1) && in(MemBarNode::Precedent)->in(0) != NULL && in(MemBarNode::Precedent)->in(0)->is_LoadBarrier()) {
Node* load_node = in(MemBarNode::Precedent)->in(0)->in(LoadBarrierNode::Oop);
set_req(MemBarNode::Precedent, load_node);
return this;
}
}
#endif
bool progress = false;
// Eliminate volatile MemBars for scalar replaced objects.
if (can_reshape && req() == (Precedent+1)) {
bool eliminate = false;
int opc = Opcode();
if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
// Volatile field loads and stores.
Node* my_mem = in(MemBarNode::Precedent);
// The MembarAquire may keep an unused LoadNode alive through the Precedent edge
if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
// if the Precedent is a decodeN and its input (a Load) is used at more than one place,
// replace this Precedent (decodeN) with the Load instead.
if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
Node* load_node = my_mem->in(1);
set_req(MemBarNode::Precedent, load_node);
phase->is_IterGVN()->_worklist.push(my_mem);
my_mem = load_node;
} else {
assert(my_mem->unique_out() == this, "sanity");
del_req(Precedent);
phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
my_mem = NULL;
}
progress = true;
}
if (my_mem != NULL && my_mem->is_Mem()) {
const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
// Check for scalar replaced object reference.
if( t_oop != NULL && t_oop->is_known_instance_field() &&
t_oop->offset() != Type::OffsetBot &&
t_oop->offset() != Type::OffsetTop) {
eliminate = true;
}
}
} else if (opc == Op_MemBarRelease) {
// Final field stores.
Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
if ((alloc != NULL) && alloc->is_Allocate() &&
alloc->as_Allocate()->does_not_escape_thread()) {
// The allocated object does not escape.
eliminate = true;
}
}
if (eliminate) {
// Replace MemBar projections by its inputs.
PhaseIterGVN* igvn = phase->is_IterGVN();
igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
// Must return either the original node (now dead) or a new node
// (Do not return a top here, since that would break the uniqueness of top.)
return new ConINode(TypeInt::ZERO);
}
}
return progress ? this : NULL;
}
//------------------------------Value------------------------------------------
const Type* MemBarNode::Value(PhaseGVN* phase) const {
if( !in(0) ) return Type::TOP;
if( phase->type(in(0)) == Type::TOP )
return Type::TOP;
return TypeTuple::MEMBAR;
}
//------------------------------match------------------------------------------
// Construct projections for memory.
Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
switch (proj->_con) {
case TypeFunc::Control:
case TypeFunc::Memory:
return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
}
ShouldNotReachHere();
return NULL;
}
//===========================InitializeNode====================================
// SUMMARY:
// This node acts as a memory barrier on raw memory, after some raw stores.
// The 'cooked' oop value feeds from the Initialize, not the Allocation.
// The Initialize can 'capture' suitably constrained stores as raw inits.
// It can coalesce related raw stores into larger units (called 'tiles').
// It can avoid zeroing new storage for memory units which have raw inits.
// At macro-expansion, it is marked 'complete', and does not optimize further.
//
// EXAMPLE:
// The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
// ctl = incoming control; mem* = incoming memory
// (Note: A star * on a memory edge denotes I/O and other standard edges.)
// First allocate uninitialized memory and fill in the header:
// alloc = (Allocate ctl mem* 16 #short[].klass ...)
// ctl := alloc.Control; mem* := alloc.Memory*
// rawmem = alloc.Memory; rawoop = alloc.RawAddress
// Then initialize to zero the non-header parts of the raw memory block:
// init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
// ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
// After the initialize node executes, the object is ready for service:
// oop := (CheckCastPP init.Control alloc.RawAddress #short[])
// Suppose its body is immediately initialized as {1,2}:
// store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
// store2 = (StoreC init.Control store1 (+ oop 14) 2)
// mem.SLICE(#short[*]) := store2
//
// DETAILS:
// An InitializeNode collects and isolates object initialization after
// an AllocateNode and before the next possible safepoint. As a
// memory barrier (MemBarNode), it keeps critical stores from drifting
// down past any safepoint or any publication of the allocation.
// Before this barrier, a newly-allocated object may have uninitialized bits.
// After this barrier, it may be treated as a real oop, and GC is allowed.
//
// The semantics of the InitializeNode include an implicit zeroing of
// the new object from object header to the end of the object.
// (The object header and end are determined by the AllocateNode.)
//
// Certain stores may be added as direct inputs to the InitializeNode.
// These stores must update raw memory, and they must be to addresses
// derived from the raw address produced by AllocateNode, and with
// a constant offset. They must be ordered by increasing offset.
// The first one is at in(RawStores), the last at in(req()-1).
// Unlike most memory operations, they are not linked in a chain,
// but are displayed in parallel as users of the rawmem output of
// the allocation.
//
// (See comments in InitializeNode::capture_store, which continue
// the example given above.)
//
// When the associated Allocate is macro-expanded, the InitializeNode
// may be rewritten to optimize collected stores. A ClearArrayNode
// may also be created at that point to represent any required zeroing.
// The InitializeNode is then marked 'complete', prohibiting further
// capturing of nearby memory operations.
//
// During macro-expansion, all captured initializations which store
// constant values of 32 bits or smaller are coalesced (if advantageous)
// into larger 'tiles' 32 or 64 bits. This allows an object to be
// initialized in fewer memory operations. Memory words which are
// covered by neither tiles nor non-constant stores are pre-zeroed
// by explicit stores of zero. (The code shape happens to do all
// zeroing first, then all other stores, with both sequences occurring
// in order of ascending offsets.)
//
// Alternatively, code may be inserted between an AllocateNode and its
// InitializeNode, to perform arbitrary initialization of the new object.
// E.g., the object copying intrinsics insert complex data transfers here.
// The initialization must then be marked as 'complete' disable the
// built-in zeroing semantics and the collection of initializing stores.
//
// While an InitializeNode is incomplete, reads from the memory state
// produced by it are optimizable if they match the control edge and
// new oop address associated with the allocation/initialization.
// They return a stored value (if the offset matches) or else zero.
// A write to the memory state, if it matches control and address,
// and if it is to a constant offset, may be 'captured' by the
// InitializeNode. It is cloned as a raw memory operation and rewired
// inside the initialization, to the raw oop produced by the allocation.
// Operations on addresses which are provably distinct (e.g., to
// other AllocateNodes) are allowed to bypass the initialization.
//
// The effect of all this is to consolidate object initialization
// (both arrays and non-arrays, both piecewise and bulk) into a
// single location, where it can be optimized as a unit.
//
// Only stores with an offset less than TrackedInitializationLimit words
// will be considered for capture by an InitializeNode. This puts a
// reasonable limit on the complexity of optimized initializations.
//---------------------------InitializeNode------------------------------------
InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
: _is_complete(Incomplete), _does_not_escape(false),
MemBarNode(C, adr_type, rawoop)
{
init_class_id(Class_Initialize);
assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
assert(in(RawAddress) == rawoop, "proper init");
// Note: allocation() can be NULL, for secondary initialization barriers
}
// Since this node is not matched, it will be processed by the
// register allocator. Declare that there are no constraints
// on the allocation of the RawAddress edge.
const RegMask &InitializeNode::in_RegMask(uint idx) const {
// This edge should be set to top, by the set_complete. But be conservative.
if (idx == InitializeNode::RawAddress)
return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
return RegMask::Empty;
}
Node* InitializeNode::memory(uint alias_idx) {
Node* mem = in(Memory);
if (mem->is_MergeMem()) {
return mem->as_MergeMem()->memory_at(alias_idx);
} else {
// incoming raw memory is not split
return mem;
}
}
bool InitializeNode::is_non_zero() {
if (is_complete()) return false;
remove_extra_zeroes();
return (req() > RawStores);
}
void InitializeNode::set_complete(PhaseGVN* phase) {
assert(!is_complete(), "caller responsibility");
_is_complete = Complete;
// After this node is complete, it contains a bunch of
// raw-memory initializations. There is no need for
// it to have anything to do with non-raw memory effects.
// Therefore, tell all non-raw users to re-optimize themselves,
// after skipping the memory effects of this initialization.
PhaseIterGVN* igvn = phase->is_IterGVN();
if (igvn) igvn->add_users_to_worklist(this);
}
// convenience function
// return false if the init contains any stores already
bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
InitializeNode* init = initialization();
if (init == NULL || init->is_complete()) return false;
init->remove_extra_zeroes();
// for now, if this allocation has already collected any inits, bail:
if (init->is_non_zero()) return false;
init->set_complete(phase);
return true;
}
void InitializeNode::remove_extra_zeroes() {
if (req() == RawStores) return;
Node* zmem = zero_memory();
uint fill = RawStores;
for (uint i = fill; i < req(); i++) {
Node* n = in(i);
if (n->is_top() || n == zmem) continue; // skip
if (fill < i) set_req(fill, n); // compact
++fill;
}
// delete any empty spaces created:
while (fill < req()) {
del_req(fill);
}
}
// Helper for remembering which stores go with which offsets.
intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
intptr_t offset = -1;
Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
phase, offset);
if (base == NULL) return -1; // something is dead,
if (offset < 0) return -1; // dead, dead
return offset;
}
// Helper for proving that an initialization expression is
// "simple enough" to be folded into an object initialization.
// Attempts to prove that a store's initial value 'n' can be captured
// within the initialization without creating a vicious cycle, such as:
// { Foo p = new Foo(); p.next = p; }
// True for constants and parameters and small combinations thereof.
bool InitializeNode::detect_init_independence(Node* n, int& count) {
if (n == NULL) return true; // (can this really happen?)
if (n->is_Proj()) n = n->in(0);
if (n == this) return false; // found a cycle
if (n->is_Con()) return true;
if (n->is_Start()) return true; // params, etc., are OK
if (n->is_Root()) return true; // even better
Node* ctl = n->in(0);
if (ctl != NULL && !ctl->is_top()) {
if (ctl->is_Proj()) ctl = ctl->in(0);
if (ctl == this) return false;
// If we already know that the enclosing memory op is pinned right after
// the init, then any control flow that the store has picked up
// must have preceded the init, or else be equal to the init.
// Even after loop optimizations (which might change control edges)
// a store is never pinned *before* the availability of its inputs.
if (!MemNode::all_controls_dominate(n, this))
return false; // failed to prove a good control
}
// Check data edges for possible dependencies on 'this'.
if ((count += 1) > 20) return false; // complexity limit
for (uint i = 1; i < n->req(); i++) {
Node* m = n->in(i);
if (m == NULL || m == n || m->is_top()) continue;
uint first_i = n->find_edge(m);
if (i != first_i) continue; // process duplicate edge just once
if (!detect_init_independence(m, count)) {
return false;
}
}
return true;
}
// Here are all the checks a Store must pass before it can be moved into
// an initialization. Returns zero if a check fails.
// On success, returns the (constant) offset to which the store applies,
// within the initialized memory.
intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
const int FAIL = 0;
if (st->is_unaligned_access()) {
return FAIL;
}
if (st->req() != MemNode::ValueIn + 1)
return FAIL; // an inscrutable StoreNode (card mark?)
Node* ctl = st->in(MemNode::Control);
if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
return FAIL; // must be unconditional after the initialization
Node* mem = st->in(MemNode::Memory);
if (!(mem->is_Proj() && mem->in(0) == this))
return FAIL; // must not be preceded by other stores
Node* adr = st->in(MemNode::Address);
intptr_t offset;
AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
if (alloc == NULL)
return FAIL; // inscrutable address
if (alloc != allocation())
return FAIL; // wrong allocation! (store needs to float up)
Node* val = st->in(MemNode::ValueIn);
int complexity_count = 0;
if (!detect_init_independence(val, complexity_count))
return FAIL; // stored value must be 'simple enough'
// The Store can be captured only if nothing after the allocation
// and before the Store is using the memory location that the store
// overwrites.
bool failed = false;
// If is_complete_with_arraycopy() is true the shape of the graph is
// well defined and is safe so no need for extra checks.
if (!is_complete_with_arraycopy()) {
// We are going to look at each use of the memory state following
// the allocation to make sure nothing reads the memory that the
// Store writes.
const TypePtr* t_adr = phase->type(adr)->isa_ptr();
int alias_idx = phase->C->get_alias_index(t_adr);
ResourceMark rm;
Unique_Node_List mems;
mems.push(mem);
Node* unique_merge = NULL;
for (uint next = 0; next < mems.size(); ++next) {
Node *m = mems.at(next);
for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
Node *n = m->fast_out(j);
if (n->outcnt() == 0) {
continue;
}
if (n == st) {
continue;
} else if (n->in(0) != NULL && n->in(0) != ctl) {
// If the control of this use is different from the control
// of the Store which is right after the InitializeNode then
// this node cannot be between the InitializeNode and the
// Store.
continue;
} else if (n->is_MergeMem()) {
if (n->as_MergeMem()->memory_at(alias_idx) == m) {
// We can hit a MergeMemNode (that will likely go away
// later) that is a direct use of the memory state
// following the InitializeNode on the same slice as the
// store node that we'd like to capture. We need to check
// the uses of the MergeMemNode.
mems.push(n);
}
} else if (n->is_Mem()) {
Node* other_adr = n->in(MemNode::Address);
if (other_adr == adr) {
failed = true;
break;
} else {
const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
if (other_t_adr != NULL) {
int other_alias_idx = phase->C->get_alias_index(other_t_adr);
if (other_alias_idx == alias_idx) {
// A load from the same memory slice as the store right
// after the InitializeNode. We check the control of the
// object/array that is loaded from. If it's the same as
// the store control then we cannot capture the store.
assert(!n->is_Store(), "2 stores to same slice on same control?");
Node* base = other_adr;
assert(base->is_AddP(), "should be addp but is %s", base->Name());
base = base->in(AddPNode::Base);
if (base != NULL) {
base = base->uncast();
if (base->is_Proj() && base->in(0) == alloc) {
failed = true;
break;
}
}
}
}
}
} else {
failed = true;
break;
}
}
}
}
if (failed) {
if (!can_reshape) {
// We decided we couldn't capture the store during parsing. We
// should try again during the next IGVN once the graph is
// cleaner.
phase->C->record_for_igvn(st);
}
return FAIL;
}
return offset; // success
}
// Find the captured store in(i) which corresponds to the range
// [start..start+size) in the initialized object.
// If there is one, return its index i. If there isn't, return the
// negative of the index where it should be inserted.
// Return 0 if the queried range overlaps an initialization boundary
// or if dead code is encountered.
// If size_in_bytes is zero, do not bother with overlap checks.
int InitializeNode::captured_store_insertion_point(intptr_t start,
int size_in_bytes,
PhaseTransform* phase) {
const int FAIL = 0, MAX_STORE = BytesPerLong;
if (is_complete())
return FAIL; // arraycopy got here first; punt
assert(allocation() != NULL, "must be present");
// no negatives, no header fields:
if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
// after a certain size, we bail out on tracking all the stores:
intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
if (start >= ti_limit) return FAIL;
for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
if (i >= limit) return -(int)i; // not found; here is where to put it
Node* st = in(i);
intptr_t st_off = get_store_offset(st, phase);
if (st_off < 0) {
if (st != zero_memory()) {
return FAIL; // bail out if there is dead garbage
}
} else if (st_off > start) {
// ...we are done, since stores are ordered
if (st_off < start + size_in_bytes) {
return FAIL; // the next store overlaps
}
return -(int)i; // not found; here is where to put it
} else if (st_off < start) {
if (size_in_bytes != 0 &&
start < st_off + MAX_STORE &&
start < st_off + st->as_Store()->memory_size()) {
return FAIL; // the previous store overlaps
}
} else {
if (size_in_bytes != 0 &&
st->as_Store()->memory_size() != size_in_bytes) {
return FAIL; // mismatched store size
}
return i;
}
++i;
}
}
// Look for a captured store which initializes at the offset 'start'
// with the given size. If there is no such store, and no other
// initialization interferes, then return zero_memory (the memory
// projection of the AllocateNode).
Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
PhaseTransform* phase) {
assert(stores_are_sane(phase), "");
int i = captured_store_insertion_point(start, size_in_bytes, phase);
if (i == 0) {
return NULL; // something is dead
} else if (i < 0) {
return zero_memory(); // just primordial zero bits here
} else {
Node* st = in(i); // here is the store at this position
assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
return st;
}
}
// Create, as a raw pointer, an address within my new object at 'offset'.
Node* InitializeNode::make_raw_address(intptr_t offset,
PhaseTransform* phase) {
Node* addr = in(RawAddress);
if (offset != 0) {
Compile* C = phase->C;
addr = phase->transform( new AddPNode(C->top(), addr,
phase->MakeConX(offset)) );
}
return addr;
}
// Clone the given store, converting it into a raw store
// initializing a field or element of my new object.
// Caller is responsible for retiring the original store,
// with subsume_node or the like.
//
// From the example above InitializeNode::InitializeNode,
// here are the old stores to be captured:
// store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
// store2 = (StoreC init.Control store1 (+ oop 14) 2)
//
// Here is the changed code; note the extra edges on init:
// alloc = (Allocate ...)
// rawoop = alloc.RawAddress
// rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
// rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
// init = (Initialize alloc.Control alloc.Memory rawoop
// rawstore1 rawstore2)
//
Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
PhaseTransform* phase, bool can_reshape) {
assert(stores_are_sane(phase), "");
if (start < 0) return NULL;
assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
Compile* C = phase->C;
int size_in_bytes = st->memory_size();
int i = captured_store_insertion_point(start, size_in_bytes, phase);
if (i == 0) return NULL; // bail out
Node* prev_mem = NULL; // raw memory for the captured store
if (i > 0) {
prev_mem = in(i); // there is a pre-existing store under this one
set_req(i, C->top()); // temporarily disconnect it
// See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
} else {
i = -i; // no pre-existing store
prev_mem = zero_memory(); // a slice of the newly allocated object
if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
set_req(--i, C->top()); // reuse this edge; it has been folded away
else
ins_req(i, C->top()); // build a new edge
}
Node* new_st = st->clone();
new_st->set_req(MemNode::Control, in(Control));
new_st->set_req(MemNode::Memory, prev_mem);
new_st->set_req(MemNode::Address, make_raw_address(start, phase));
new_st = phase->transform(new_st);
// At this point, new_st might have swallowed a pre-existing store
// at the same offset, or perhaps new_st might have disappeared,
// if it redundantly stored the same value (or zero to fresh memory).
// In any case, wire it in:
phase->igvn_rehash_node_delayed(this);
set_req(i, new_st);
// The caller may now kill the old guy.
DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
assert(check_st == new_st || check_st == NULL, "must be findable");
assert(!is_complete(), "");
return new_st;
}
static bool store_constant(jlong* tiles, int num_tiles,
intptr_t st_off, int st_size,
jlong con) {
if ((st_off & (st_size-1)) != 0)
return false; // strange store offset (assume size==2**N)
address addr = (address)tiles + st_off;
assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
switch (st_size) {
case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
case sizeof(jint): *(jint*) addr = (jint) con; break;
case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
default: return false; // strange store size (detect size!=2**N here)
}
return true; // return success to caller
}
// Coalesce subword constants into int constants and possibly
// into long constants. The goal, if the CPU permits,
// is to initialize the object with a small number of 64-bit tiles.
// Also, convert floating-point constants to bit patterns.
// Non-constants are not relevant to this pass.
//
// In terms of the running example on InitializeNode::InitializeNode
// and InitializeNode::capture_store, here is the transformation
// of rawstore1 and rawstore2 into rawstore12:
// alloc = (Allocate ...)
// rawoop = alloc.RawAddress
// tile12 = 0x00010002
// rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
// init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
//
void
InitializeNode::coalesce_subword_stores(intptr_t header_size,
Node* size_in_bytes,
PhaseGVN* phase) {
Compile* C = phase->C;
assert(stores_are_sane(phase), "");
// Note: After this pass, they are not completely sane,
// since there may be some overlaps.
int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
size_limit = MIN2(size_limit, ti_limit);
size_limit = align_up(size_limit, BytesPerLong);
int num_tiles = size_limit / BytesPerLong;
// allocate space for the tile map:
const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
jlong tiles_buf[small_len];
Node* nodes_buf[small_len];
jlong inits_buf[small_len];
jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
: NEW_RESOURCE_ARRAY(jlong, num_tiles));
Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
: NEW_RESOURCE_ARRAY(Node*, num_tiles));
jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
: NEW_RESOURCE_ARRAY(jlong, num_tiles));
// tiles: exact bitwise model of all primitive constants
// nodes: last constant-storing node subsumed into the tiles model
// inits: which bytes (in each tile) are touched by any initializations
//// Pass A: Fill in the tile model with any relevant stores.
Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
Node* zmem = zero_memory(); // initially zero memory state
for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
Node* st = in(i);
intptr_t st_off = get_store_offset(st, phase);
// Figure out the store's offset and constant value:
if (st_off < header_size) continue; //skip (ignore header)
if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
int st_size = st->as_Store()->memory_size();
if (st_off + st_size > size_limit) break;
// Record which bytes are touched, whether by constant or not.
if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
continue; // skip (strange store size)
const Type* val = phase->type(st->in(MemNode::ValueIn));
if (!val->singleton()) continue; //skip (non-con store)
BasicType type = val->basic_type();
jlong con = 0;
switch (type) {
case T_INT: con = val->is_int()->get_con(); break;
case T_LONG: con = val->is_long()->get_con(); break;
case T_FLOAT: con = jint_cast(val->getf()); break;
case T_DOUBLE: con = jlong_cast(val->getd()); break;
default: continue; //skip (odd store type)
}
if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
st->Opcode() == Op_StoreL) {
continue; // This StoreL is already optimal.
}
// Store down the constant.
store_constant(tiles, num_tiles, st_off, st_size, con);
intptr_t j = st_off >> LogBytesPerLong;
if (type == T_INT && st_size == BytesPerInt
&& (st_off & BytesPerInt) == BytesPerInt) {
jlong lcon = tiles[j];
if (!Matcher::isSimpleConstant64(lcon) &&
st->Opcode() == Op_StoreI) {
// This StoreI is already optimal by itself.
jint* intcon = (jint*) &tiles[j];
intcon[1] = 0; // undo the store_constant()
// If the previous store is also optimal by itself, back up and
// undo the action of the previous loop iteration... if we can.
// But if we can't, just let the previous half take care of itself.
st = nodes[j];
st_off -= BytesPerInt;
con = intcon[0];
if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
assert(st_off >= header_size, "still ignoring header");
assert(get_store_offset(st, phase) == st_off, "must be");
assert(in(i-1) == zmem, "must be");
DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
assert(con == tcon->is_int()->get_con(), "must be");
// Undo the effects of the previous loop trip, which swallowed st:
intcon[0] = 0; // undo store_constant()
set_req(i-1, st); // undo set_req(i, zmem)
nodes[j] = NULL; // undo nodes[j] = st
--old_subword; // undo ++old_subword
}
continue; // This StoreI is already optimal.
}
}
// This store is not needed.
set_req(i, zmem);
nodes[j] = st; // record for the moment
if (st_size < BytesPerLong) // something has changed
++old_subword; // includes int/float, but who's counting...
else ++old_long;
}
if ((old_subword + old_long) == 0)
return; // nothing more to do
//// Pass B: Convert any non-zero tiles into optimal constant stores.
// Be sure to insert them before overlapping non-constant stores.
// (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
for (int j = 0; j < num_tiles; j++) {
jlong con = tiles[j];
jlong init = inits[j];
if (con == 0) continue;
jint con0, con1; // split the constant, address-wise
jint init0, init1; // split the init map, address-wise
{ union { jlong con; jint intcon[2]; } u;
u.con = con;
con0 = u.intcon[0];
con1 = u.intcon[1];
u.con = init;
init0 = u.intcon[0];
init1 = u.intcon[1];
}
Node* old = nodes[j];
assert(old != NULL, "need the prior store");
intptr_t offset = (j * BytesPerLong);
bool split = !Matcher::isSimpleConstant64(con);
if (offset < header_size) {
assert(offset + BytesPerInt >= header_size, "second int counts");
assert(*(jint*)&tiles[j] == 0, "junk in header");
split = true; // only the second word counts
// Example: int a[] = { 42 ... }
} else if (con0 == 0 && init0 == -1) {
split = true; // first word is covered by full inits
// Example: int a[] = { ... foo(), 42 ... }
} else if (con1 == 0 && init1 == -1) {
split = true; // second word is covered by full inits
// Example: int a[] = { ... 42, foo() ... }
}
// Here's a case where init0 is neither 0 nor -1:
// byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
// Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
// In this case the tile is not split; it is (jlong)42.
// The big tile is stored down, and then the foo() value is inserted.
// (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
Node* ctl = old->in(MemNode::Control);
Node* adr = make_raw_address(offset, phase);
const TypePtr* atp = TypeRawPtr::BOTTOM;
// One or two coalesced stores to plop down.
Node* st[2];
intptr_t off[2];
int nst = 0;
if (!split) {
++new_long;
off[nst] = offset;
st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
phase->longcon(con), T_LONG, MemNode::unordered);
} else {
// Omit either if it is a zero.
if (con0 != 0) {
++new_int;
off[nst] = offset;
st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
phase->intcon(con0), T_INT, MemNode::unordered);
}
if (con1 != 0) {
++new_int;
offset += BytesPerInt;
adr = make_raw_address(offset, phase);
off[nst] = offset;
st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
phase->intcon(con1), T_INT, MemNode::unordered);
}
}
// Insert second store first, then the first before the second.
// Insert each one just before any overlapping non-constant stores.
while (nst > 0) {
Node* st1 = st[--nst];
C->copy_node_notes_to(st1, old);
st1 = phase->transform(st1);
offset = off[nst];
assert(offset >= header_size, "do not smash header");
int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
guarantee(ins_idx != 0, "must re-insert constant store");
if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
set_req(--ins_idx, st1);
else
ins_req(ins_idx, st1);
}
}
if (PrintCompilation && WizardMode)
tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
old_subword, old_long, new_int, new_long);
if (C->log() != NULL)
C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
old_subword, old_long, new_int, new_long);
// Clean up any remaining occurrences of zmem:
remove_extra_zeroes();
}
// Explore forward from in(start) to find the first fully initialized
// word, and return its offset. Skip groups of subword stores which
// together initialize full words. If in(start) is itself part of a
// fully initialized word, return the offset of in(start). If there
// are no following full-word stores, or if something is fishy, return
// a negative value.
intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
int int_map = 0;
intptr_t int_map_off = 0;
const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
for (uint i = start, limit = req(); i < limit; i++) {
Node* st = in(i);
intptr_t st_off = get_store_offset(st, phase);
if (st_off < 0) break; // return conservative answer
int st_size = st->as_Store()->memory_size();
if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
return st_off; // we found a complete word init
}
// update the map:
intptr_t this_int_off = align_down(st_off, BytesPerInt);
if (this_int_off != int_map_off) {
// reset the map:
int_map = 0;
int_map_off = this_int_off;
}
int subword_off = st_off - this_int_off;
int_map |= right_n_bits(st_size) << subword_off;
if ((int_map & FULL_MAP) == FULL_MAP) {
return this_int_off; // we found a complete word init
}
// Did this store hit or cross the word boundary?
intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
if (next_int_off == this_int_off + BytesPerInt) {
// We passed the current int, without fully initializing it.
int_map_off = next_int_off;
int_map >>= BytesPerInt;
} else if (next_int_off > this_int_off + BytesPerInt) {
// We passed the current and next int.
return this_int_off + BytesPerInt;
}
}
return -1;
}
// Called when the associated AllocateNode is expanded into CFG.
// At this point, we may perform additional optimizations.
// Linearize the stores by ascending offset, to make memory
// activity as coherent as possible.
Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
intptr_t header_size,
Node* size_in_bytes,
PhaseGVN* phase) {
assert(!is_complete(), "not already complete");
assert(stores_are_sane(phase), "");
assert(allocation() != NULL, "must be present");
remove_extra_zeroes();
if (ReduceFieldZeroing || ReduceBulkZeroing)
// reduce instruction count for common initialization patterns
coalesce_subword_stores(header_size, size_in_bytes, phase);
Node* zmem = zero_memory(); // initially zero memory state
Node* inits = zmem; // accumulating a linearized chain of inits
#ifdef ASSERT
intptr_t first_offset = allocation()->minimum_header_size();
intptr_t last_init_off = first_offset; // previous init offset
intptr_t last_init_end = first_offset; // previous init offset+size
intptr_t last_tile_end = first_offset; // previous tile offset+size
#endif
intptr_t zeroes_done = header_size;
bool do_zeroing = true; // we might give up if inits are very sparse
int big_init_gaps = 0; // how many large gaps have we seen?
if (UseTLAB && ZeroTLAB) do_zeroing = false;
if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
Node* st = in(i);
intptr_t st_off = get_store_offset(st, phase);
if (st_off < 0)
break; // unknown junk in the inits
if (st->in(MemNode::Memory) != zmem)
break; // complicated store chains somehow in list
int st_size = st->as_Store()->memory_size();
intptr_t next_init_off = st_off + st_size;
if (do_zeroing && zeroes_done < next_init_off) {
// See if this store needs a zero before it or under it.
intptr_t zeroes_needed = st_off;
if (st_size < BytesPerInt) {
// Look for subword stores which only partially initialize words.
// If we find some, we must lay down some word-level zeroes first,
// underneath the subword stores.
//
// Examples:
// byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
// byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
// byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
//
// Note: coalesce_subword_stores may have already done this,
// if it was prompted by constant non-zero subword initializers.
// But this case can still arise with non-constant stores.
intptr_t next_full_store = find_next_fullword_store(i, phase);
// In the examples above:
// in(i) p q r s x y z
// st_off 12 13 14 15 12 13 14
// st_size 1 1 1 1 1 1 1
// next_full_s. 12 16 16 16 16 16 16
// z's_done 12 16 16 16 12 16 12
// z's_needed 12 16 16 16 16 16 16
// zsize 0 0 0 0 4 0 4
if (next_full_store < 0) {
// Conservative tack: Zero to end of current word.
zeroes_needed = align_up(zeroes_needed, BytesPerInt);
} else {
// Zero to beginning of next fully initialized word.
// Or, don't zero at all, if we are already in that word.
assert(next_full_store >= zeroes_needed, "must go forward");
assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
zeroes_needed = next_full_store;
}
}
if (zeroes_needed > zeroes_done) {
intptr_t zsize = zeroes_needed - zeroes_done;
// Do some incremental zeroing on rawmem, in parallel with inits.
zeroes_done = align_down(zeroes_done, BytesPerInt);
rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
zeroes_done, zeroes_needed,
phase);
zeroes_done = zeroes_needed;
if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
do_zeroing = false; // leave the hole, next time
}
}
// Collect the store and move on:
st->set_req(MemNode::Memory, inits);
inits = st; // put it on the linearized chain
set_req(i, zmem); // unhook from previous position
if (zeroes_done == st_off)
zeroes_done = next_init_off;
assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
#ifdef ASSERT
// Various order invariants. Weaker than stores_are_sane because
// a large constant tile can be filled in by smaller non-constant stores.
assert(st_off >= last_init_off, "inits do not reverse");
last_init_off = st_off;
const Type* val = NULL;
if (st_size >= BytesPerInt &&
(val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
(int)val->basic_type() < (int)T_OBJECT) {
assert(st_off >= last_tile_end, "tiles do not overlap");
assert(st_off >= last_init_end, "tiles do not overwrite inits");
last_tile_end = MAX2(last_tile_end, next_init_off);
} else {
intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
assert(st_tile_end >= last_tile_end, "inits stay with tiles");
assert(st_off >= last_init_end, "inits do not overlap");
last_init_end = next_init_off; // it's a non-tile
}
#endif //ASSERT
}
remove_extra_zeroes(); // clear out all the zmems left over
add_req(inits);
if (!(UseTLAB && ZeroTLAB)) {
// If anything remains to be zeroed, zero it all now.
zeroes_done = align_down(zeroes_done, BytesPerInt);
// if it is the last unused 4 bytes of an instance, forget about it
intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
if (zeroes_done + BytesPerLong >= size_limit) {
AllocateNode* alloc = allocation();
assert(alloc != NULL, "must be present");
if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
Node* klass_node = alloc->in(AllocateNode::KlassNode);
ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
if (zeroes_done == k->layout_helper())
zeroes_done = size_limit;
}
}
if (zeroes_done < size_limit) {
rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
zeroes_done, size_in_bytes, phase);
}
}
set_complete(phase);
return rawmem;
}
#ifdef ASSERT
bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
if (is_complete())
return true; // stores could be anything at this point
assert(allocation() != NULL, "must be present");
intptr_t last_off = allocation()->minimum_header_size();
for (uint i = InitializeNode::RawStores; i < req(); i++) {
Node* st = in(i);
intptr_t st_off = get_store_offset(st, phase);
if (st_off < 0) continue; // ignore dead garbage
if (last_off > st_off) {
tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
this->dump(2);
assert(false, "ascending store offsets");
return false;
}
last_off = st_off + st->as_Store()->memory_size();
}
return true;
}
#endif //ASSERT
//============================MergeMemNode=====================================
//
// SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
// contributing store or call operations. Each contributor provides the memory
// state for a particular "alias type" (see Compile::alias_type). For example,
// if a MergeMem has an input X for alias category #6, then any memory reference
// to alias category #6 may use X as its memory state input, as an exact equivalent
// to using the MergeMem as a whole.
// Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
//
// (Here, the <N> notation gives the index of the relevant adr_type.)
//
// In one special case (and more cases in the future), alias categories overlap.
// The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
// states. Therefore, if a MergeMem has only one contributing input W for Bot,
// it is exactly equivalent to that state W:
// MergeMem(<Bot>: W) <==> W
//
// Usually, the merge has more than one input. In that case, where inputs
// overlap (i.e., one is Bot), the narrower alias type determines the memory
// state for that type, and the wider alias type (Bot) fills in everywhere else:
// Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
// Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
//
// A merge can take a "wide" memory state as one of its narrow inputs.
// This simply means that the merge observes out only the relevant parts of
// the wide input. That is, wide memory states arriving at narrow merge inputs
// are implicitly "filtered" or "sliced" as necessary. (This is rare.)
//
// These rules imply that MergeMem nodes may cascade (via their <Bot> links),
// and that memory slices "leak through":
// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
//
// But, in such a cascade, repeated memory slices can "block the leak":
// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
//
// In the last example, Y is not part of the combined memory state of the
// outermost MergeMem. The system must, of course, prevent unschedulable
// memory states from arising, so you can be sure that the state Y is somehow
// a precursor to state Y'.
//
//
// REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
// of each MergeMemNode array are exactly the numerical alias indexes, including
// but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
// Compile::alias_type (and kin) produce and manage these indexes.
//
// By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
// (Note that this provides quick access to the top node inside MergeMem methods,
// without the need to reach out via TLS to Compile::current.)
//
// As a consequence of what was just described, a MergeMem that represents a full
// memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
// containing all alias categories.
//
// MergeMem nodes never (?) have control inputs, so in(0) is NULL.
//
// All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
// a memory state for the alias type <N>, or else the top node, meaning that
// there is no particular input for that alias type. Note that the length of
// a MergeMem is variable, and may be extended at any time to accommodate new
// memory states at larger alias indexes. When merges grow, they are of course
// filled with "top" in the unused in() positions.
//
// This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
// (Top was chosen because it works smoothly with passes like GCM.)
//
// For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
// the type of random VM bits like TLS references.) Since it is always the
// first non-Bot memory slice, some low-level loops use it to initialize an
// index variable: for (i = AliasIdxRaw; i < req(); i++).
//
//
// ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
// the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
// the memory state for alias type <N>, or (if there is no particular slice at <N>,
// it returns the base memory. To prevent bugs, memory_at does not accept <Top>
// or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
// MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
//
// %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
// really that different from the other memory inputs. An abbreviation called
// "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
//
//
// PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
// partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
// that "emerges though" the base memory will be marked as excluding the alias types
// of the other (narrow-memory) copies which "emerged through" the narrow edges:
//
// Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
// ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
//
// This strange "subtraction" effect is necessary to ensure IGVN convergence.
// (It is currently unimplemented.) As you can see, the resulting merge is
// actually a disjoint union of memory states, rather than an overlay.
//
//------------------------------MergeMemNode-----------------------------------
Node* MergeMemNode::make_empty_memory() {
Node* empty_memory = (Node*) Compile::current()->top();
assert(empty_memory->is_top(), "correct sentinel identity");
return empty_memory;
}
MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
init_class_id(Class_MergeMem);
// all inputs are nullified in Node::Node(int)
// set_input(0, NULL); // no control input
// Initialize the edges uniformly to top, for starters.
Node* empty_mem = make_empty_memory();
for (uint i = Compile::AliasIdxTop; i < req(); i++) {
init_req(i,empty_mem);
}
assert(empty_memory() == empty_mem, "");
if( new_base != NULL && new_base->is_MergeMem() ) {
MergeMemNode* mdef = new_base->as_MergeMem();
assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
mms.set_memory(mms.memory2());
}
assert(base_memory() == mdef->base_memory(), "");
} else {
set_base_memory(new_base);
}
}
// Make a new, untransformed MergeMem with the same base as 'mem'.
// If mem is itself a MergeMem, populate the result with the same edges.
MergeMemNode* MergeMemNode::make(Node* mem) {
return new MergeMemNode(mem);
}
//------------------------------cmp--------------------------------------------
uint MergeMemNode::hash() const { return NO_HASH; }
uint MergeMemNode::cmp( const Node &n ) const {
return (&n == this); // Always fail except on self
}
//------------------------------Identity---------------------------------------
Node* MergeMemNode::Identity(PhaseGVN* phase) {
// Identity if this merge point does not record any interesting memory
// disambiguations.
Node* base_mem = base_memory();
Node* empty_mem = empty_memory();
if (base_mem != empty_mem) { // Memory path is not dead?
for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
Node* mem = in(i);
if (mem != empty_mem && mem != base_mem) {
return this; // Many memory splits; no change
}
}
}
return base_mem; // No memory splits; ID on the one true input
}
//------------------------------Ideal------------------------------------------
// This method is invoked recursively on chains of MergeMem nodes
Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
// Remove chain'd MergeMems
//
// This is delicate, because the each "in(i)" (i >= Raw) is interpreted
// relative to the "in(Bot)". Since we are patching both at the same time,
// we have to be careful to read each "in(i)" relative to the old "in(Bot)",
// but rewrite each "in(i)" relative to the new "in(Bot)".
Node *progress = NULL;
Node* old_base = base_memory();
Node* empty_mem = empty_memory();
if (old_base == empty_mem)
return NULL; // Dead memory path.
MergeMemNode* old_mbase;
if (old_base != NULL && old_base->is_MergeMem())
old_mbase = old_base->as_MergeMem();
else
old_mbase = NULL;
Node* new_base = old_base;
// simplify stacked MergeMems in base memory
if (old_mbase) new_base = old_mbase->base_memory();
// the base memory might contribute new slices beyond my req()
if (old_mbase) grow_to_match(old_mbase);
// Look carefully at the base node if it is a phi.
PhiNode* phi_base;
if (new_base != NULL && new_base->is_Phi())
phi_base = new_base->as_Phi();
else
phi_base = NULL;
Node* phi_reg = NULL;
uint phi_len = (uint)-1;
if (phi_base != NULL && !phi_base->is_copy()) {
// do not examine phi if degraded to a copy
phi_reg = phi_base->region();
phi_len = phi_base->req();
// see if the phi is unfinished
for (uint i = 1; i < phi_len; i++) {
if (phi_base->in(i) == NULL) {
// incomplete phi; do not look at it yet!
phi_reg = NULL;
phi_len = (uint)-1;
break;
}
}
}
// Note: We do not call verify_sparse on entry, because inputs
// can normalize to the base_memory via subsume_node or similar
// mechanisms. This method repairs that damage.
assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
// Look at each slice.
for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
Node* old_in = in(i);
// calculate the old memory value
Node* old_mem = old_in;
if (old_mem == empty_mem) old_mem = old_base;
assert(old_mem == memory_at(i), "");
// maybe update (reslice) the old memory value
// simplify stacked MergeMems
Node* new_mem = old_mem;
MergeMemNode* old_mmem;
if (old_mem != NULL && old_mem->is_MergeMem())
old_mmem = old_mem->as_MergeMem();
else
old_mmem = NULL;
if (old_mmem == this) {
// This can happen if loops break up and safepoints disappear.
// A merge of BotPtr (default) with a RawPtr memory derived from a
// safepoint can be rewritten to a merge of the same BotPtr with
// the BotPtr phi coming into the loop. If that phi disappears
// also, we can end up with a self-loop of the mergemem.
// In general, if loops degenerate and memory effects disappear,
// a mergemem can be left looking at itself. This simply means
// that the mergemem's default should be used, since there is
// no longer any apparent effect on this slice.
// Note: If a memory slice is a MergeMem cycle, it is unreachable
// from start. Update the input to TOP.
new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
}
else if (old_mmem != NULL) {
new_mem = old_mmem->memory_at(i);
}
// else preceding memory was not a MergeMem
// replace equivalent phis (unfortunately, they do not GVN together)
if (new_mem != NULL && new_mem != new_base &&
new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
if (new_mem->is_Phi()) {
PhiNode* phi_mem = new_mem->as_Phi();
for (uint i = 1; i < phi_len; i++) {
if (phi_base->in(i) != phi_mem->in(i)) {
phi_mem = NULL;
break;
}
}
if (phi_mem != NULL) {
// equivalent phi nodes; revert to the def
new_mem = new_base;
}
}
}
// maybe store down a new value
Node* new_in = new_mem;
if (new_in == new_base) new_in = empty_mem;
if (new_in != old_in) {
// Warning: Do not combine this "if" with the previous "if"
// A memory slice might have be be rewritten even if it is semantically
// unchanged, if the base_memory value has changed.
set_req(i, new_in);
progress = this; // Report progress
}
}
if (new_base != old_base) {
set_req(Compile::AliasIdxBot, new_base);
// Don't use set_base_memory(new_base), because we need to update du.
assert(base_memory() == new_base, "");
progress = this;
}
if( base_memory() == this ) {
// a self cycle indicates this memory path is dead
set_req(Compile::AliasIdxBot, empty_mem);
}
// Resolve external cycles by calling Ideal on a MergeMem base_memory
// Recursion must occur after the self cycle check above
if( base_memory()->is_MergeMem() ) {
MergeMemNode *new_mbase = base_memory()->as_MergeMem();
Node *m = phase->transform(new_mbase); // Rollup any cycles
if( m != NULL &&
(m->is_top() ||
(m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
// propagate rollup of dead cycle to self
set_req(Compile::AliasIdxBot, empty_mem);
}
}
if( base_memory() == empty_mem ) {
progress = this;
// Cut inputs during Parse phase only.
// During Optimize phase a dead MergeMem node will be subsumed by Top.
if( !can_reshape ) {
for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
if( in(i) != empty_mem ) { set_req(i, empty_mem); }
}
}
}
if( !progress && base_memory()->is_Phi() && can_reshape ) {
// Check if PhiNode::Ideal's "Split phis through memory merges"
// transform should be attempted. Look for this->phi->this cycle.
uint merge_width = req();
if (merge_width > Compile::AliasIdxRaw) {
PhiNode* phi = base_memory()->as_Phi();
for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
if (phi->in(i) == this) {
phase->is_IterGVN()->_worklist.push(phi);
break;
}
}
}
}
assert(progress || verify_sparse(), "please, no dups of base");
return progress;
}
//-------------------------set_base_memory-------------------------------------
void MergeMemNode::set_base_memory(Node *new_base) {
Node* empty_mem = empty_memory();
set_req(Compile::AliasIdxBot, new_base);
assert(memory_at(req()) == new_base, "must set default memory");
// Clear out other occurrences of new_base:
if (new_base != empty_mem) {
for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
if (in(i) == new_base) set_req(i, empty_mem);
}
}
}
//------------------------------out_RegMask------------------------------------
const RegMask &MergeMemNode::out_RegMask() const {
return RegMask::Empty;
}
//------------------------------dump_spec--------------------------------------
#ifndef PRODUCT
void MergeMemNode::dump_spec(outputStream *st) const {
st->print(" {");
Node* base_mem = base_memory();
for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
if (mem == base_mem) { st->print(" -"); continue; }
st->print( " N%d:", mem->_idx );
Compile::current()->get_adr_type(i)->dump_on(st);
}
st->print(" }");
}
#endif // !PRODUCT
#ifdef ASSERT
static bool might_be_same(Node* a, Node* b) {
if (a == b) return true;
if (!(a->is_Phi() || b->is_Phi())) return false;
// phis shift around during optimization
return true; // pretty stupid...
}
// verify a narrow slice (either incoming or outgoing)
static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
if (!VerifyAliases) return; // don't bother to verify unless requested
if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
if (Node::in_dump()) return; // muzzle asserts when printing
assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
assert(n != NULL, "");
// Elide intervening MergeMem's
while (n->is_MergeMem()) {
n = n->as_MergeMem()->memory_at(alias_idx);
}
Compile* C = Compile::current();
const TypePtr* n_adr_type = n->adr_type();
if (n == m->empty_memory()) {
// Implicit copy of base_memory()
} else if (n_adr_type != TypePtr::BOTTOM) {
assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
} else {
// A few places like make_runtime_call "know" that VM calls are narrow,
// and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
bool expected_wide_mem = false;
if (n == m->base_memory()) {
expected_wide_mem = true;
} else if (alias_idx == Compile::AliasIdxRaw ||
n == m->memory_at(Compile::AliasIdxRaw)) {
expected_wide_mem = true;
} else if (!C->alias_type(alias_idx)->is_rewritable()) {
// memory can "leak through" calls on channels that
// are write-once. Allow this also.
expected_wide_mem = true;
}
assert(expected_wide_mem, "expected narrow slice replacement");
}
}
#else // !ASSERT
#define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
#endif
//-----------------------------memory_at---------------------------------------
Node* MergeMemNode::memory_at(uint alias_idx) const {
assert(alias_idx >= Compile::AliasIdxRaw ||
alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
"must avoid base_memory and AliasIdxTop");
// Otherwise, it is a narrow slice.
Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
Compile *C = Compile::current();
if (is_empty_memory(n)) {
// the array is sparse; empty slots are the "top" node
n = base_memory();
assert(Node::in_dump()
|| n == NULL || n->bottom_type() == Type::TOP
|| n->adr_type() == NULL // address is TOP
|| n->adr_type() == TypePtr::BOTTOM
|| n->adr_type() == TypeRawPtr::BOTTOM
|| Compile::current()->AliasLevel() == 0,
"must be a wide memory");
// AliasLevel == 0 if we are organizing the memory states manually.
// See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
} else {
// make sure the stored slice is sane
#ifdef ASSERT
if (VMError::is_error_reported() || Node::in_dump()) {
} else if (might_be_same(n, base_memory())) {
// Give it a pass: It is a mostly harmless repetition of the base.
// This can arise normally from node subsumption during optimization.
} else {
verify_memory_slice(this, alias_idx, n);
}
#endif
}
return n;
}
//---------------------------set_memory_at-------------------------------------
void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
verify_memory_slice(this, alias_idx, n);
Node* empty_mem = empty_memory();
if (n == base_memory()) n = empty_mem; // collapse default
uint need_req = alias_idx+1;
if (req() < need_req) {
if (n == empty_mem) return; // already the default, so do not grow me
// grow the sparse array
do {
add_req(empty_mem);
} while (req() < need_req);
}
set_req( alias_idx, n );
}
//--------------------------iteration_setup------------------------------------
void MergeMemNode::iteration_setup(const MergeMemNode* other) {
if (other != NULL) {
grow_to_match(other);
// invariant: the finite support of mm2 is within mm->req()
#ifdef ASSERT
for (uint i = req(); i < other->req(); i++) {
assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
}
#endif
}
// Replace spurious copies of base_memory by top.
Node* base_mem = base_memory();
if (base_mem != NULL && !base_mem->is_top()) {
for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
if (in(i) == base_mem)
set_req(i, empty_memory());
}
}
}
//---------------------------grow_to_match-------------------------------------
void MergeMemNode::grow_to_match(const MergeMemNode* other) {
Node* empty_mem = empty_memory();
assert(other->is_empty_memory(empty_mem), "consistent sentinels");
// look for the finite support of the other memory
for (uint i = other->req(); --i >= req(); ) {
if (other->in(i) != empty_mem) {
uint new_len = i+1;
while (req() < new_len) add_req(empty_mem);
break;
}
}
}
//---------------------------verify_sparse-------------------------------------
#ifndef PRODUCT
bool MergeMemNode::verify_sparse() const {
assert(is_empty_memory(make_empty_memory()), "sane sentinel");
Node* base_mem = base_memory();
// The following can happen in degenerate cases, since empty==top.
if (is_empty_memory(base_mem)) return true;
for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
assert(in(i) != NULL, "sane slice");
if (in(i) == base_mem) return false; // should have been the sentinel value!
}
return true;
}
bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
Node* n;
n = mm->in(idx);
if (mem == n) return true; // might be empty_memory()
n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
if (mem == n) return true;
while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
if (mem == n) return true;
if (n == NULL) break;
}
return false;
}
#endif // !PRODUCT