/*
* Copyright (c) 2015, 2019, 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 "opto/castnode.hpp"
#include "opto/compile.hpp"
#include "opto/escape.hpp"
#include "opto/graphKit.hpp"
#include "opto/loopnode.hpp"
#include "opto/machnode.hpp"
#include "opto/macro.hpp"
#include "opto/memnode.hpp"
#include "opto/movenode.hpp"
#include "opto/node.hpp"
#include "opto/phase.hpp"
#include "opto/phaseX.hpp"
#include "opto/rootnode.hpp"
#include "opto/type.hpp"
#include "utilities/copy.hpp"
#include "utilities/growableArray.hpp"
#include "utilities/macros.hpp"
#include "gc/z/zBarrierSet.hpp"
#include "gc/z/c2/zBarrierSetC2.hpp"
#include "gc/z/zThreadLocalData.hpp"
#include "gc/z/zBarrierSetRuntime.hpp"
ZBarrierSetC2State::ZBarrierSetC2State(Arena* comp_arena) :
_load_barrier_nodes(new (comp_arena) GrowableArray<LoadBarrierNode*>(comp_arena, 8, 0, NULL)) {}
int ZBarrierSetC2State::load_barrier_count() const {
return _load_barrier_nodes->length();
}
void ZBarrierSetC2State::add_load_barrier_node(LoadBarrierNode * n) {
assert(!_load_barrier_nodes->contains(n), " duplicate entry in expand list");
_load_barrier_nodes->append(n);
}
void ZBarrierSetC2State::remove_load_barrier_node(LoadBarrierNode * n) {
// this function may be called twice for a node so check
// that the node is in the array before attempting to remove it
if (_load_barrier_nodes->contains(n)) {
_load_barrier_nodes->remove(n);
}
}
LoadBarrierNode* ZBarrierSetC2State::load_barrier_node(int idx) const {
return _load_barrier_nodes->at(idx);
}
void* ZBarrierSetC2::create_barrier_state(Arena* comp_arena) const {
return new(comp_arena) ZBarrierSetC2State(comp_arena);
}
ZBarrierSetC2State* ZBarrierSetC2::state() const {
return reinterpret_cast<ZBarrierSetC2State*>(Compile::current()->barrier_set_state());
}
bool ZBarrierSetC2::is_gc_barrier_node(Node* node) const {
// 1. This step follows potential oop projections of a load barrier before expansion
if (node->is_Proj()) {
node = node->in(0);
}
// 2. This step checks for unexpanded load barriers
if (node->is_LoadBarrier()) {
return true;
}
// 3. This step checks for the phi corresponding to an optimized load barrier expansion
if (node->is_Phi()) {
PhiNode* phi = node->as_Phi();
Node* n = phi->in(1);
if (n != NULL && n->is_LoadBarrierSlowReg()) {
return true;
}
}
return false;
}
void ZBarrierSetC2::register_potential_barrier_node(Node* node) const {
if (node->is_LoadBarrier()) {
state()->add_load_barrier_node(node->as_LoadBarrier());
}
}
void ZBarrierSetC2::unregister_potential_barrier_node(Node* node) const {
if (node->is_LoadBarrier()) {
state()->remove_load_barrier_node(node->as_LoadBarrier());
}
}
void ZBarrierSetC2::eliminate_useless_gc_barriers(Unique_Node_List &useful, Compile* C) const {
// Remove useless LoadBarrier nodes
ZBarrierSetC2State* s = state();
for (int i = s->load_barrier_count()-1; i >= 0; i--) {
LoadBarrierNode* n = s->load_barrier_node(i);
if (!useful.member(n)) {
unregister_potential_barrier_node(n);
}
}
}
void ZBarrierSetC2::enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const {
if (node->is_LoadBarrier() && !node->as_LoadBarrier()->has_true_uses()) {
igvn->_worklist.push(node);
}
}
const uint NoBarrier = 0;
const uint RequireBarrier = 1;
const uint WeakBarrier = 2;
const uint ExpandedBarrier = 4;
static bool load_require_barrier(LoadNode* load) { return (load->barrier_data() & RequireBarrier) == RequireBarrier; }
static bool load_has_weak_barrier(LoadNode* load) { return (load->barrier_data() & WeakBarrier) == WeakBarrier; }
static bool load_has_expanded_barrier(LoadNode* load) { return (load->barrier_data() & ExpandedBarrier) == ExpandedBarrier; }
static void load_set_expanded_barrier(LoadNode* load) { return load->set_barrier_data(ExpandedBarrier); }
static void load_set_barrier(LoadNode* load, bool weak) {
if (weak) {
load->set_barrier_data(RequireBarrier | WeakBarrier);
} else {
load->set_barrier_data(RequireBarrier);
}
}
// == LoadBarrierNode ==
LoadBarrierNode::LoadBarrierNode(Compile* C,
Node* c,
Node* mem,
Node* val,
Node* adr,
bool weak) :
MultiNode(Number_of_Inputs),
_weak(weak) {
init_req(Control, c);
init_req(Memory, mem);
init_req(Oop, val);
init_req(Address, adr);
init_req(Similar, C->top());
init_class_id(Class_LoadBarrier);
BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
bs->register_potential_barrier_node(this);
}
uint LoadBarrierNode::size_of() const {
return sizeof(*this);
}
bool LoadBarrierNode::cmp(const Node& n) const {
ShouldNotReachHere();
return false;
}
const Type *LoadBarrierNode::bottom_type() const {
const Type** floadbarrier = (const Type **)(Compile::current()->type_arena()->Amalloc_4((Number_of_Outputs)*sizeof(Type*)));
Node* in_oop = in(Oop);
floadbarrier[Control] = Type::CONTROL;
floadbarrier[Memory] = Type::MEMORY;
floadbarrier[Oop] = in_oop == NULL ? Type::TOP : in_oop->bottom_type();
return TypeTuple::make(Number_of_Outputs, floadbarrier);
}
const TypePtr* LoadBarrierNode::adr_type() const {
ShouldNotReachHere();
return NULL;
}
const Type *LoadBarrierNode::Value(PhaseGVN *phase) const {
const Type** floadbarrier = (const Type **)(phase->C->type_arena()->Amalloc_4((Number_of_Outputs)*sizeof(Type*)));
const Type* val_t = phase->type(in(Oop));
floadbarrier[Control] = Type::CONTROL;
floadbarrier[Memory] = Type::MEMORY;
floadbarrier[Oop] = val_t;
return TypeTuple::make(Number_of_Outputs, floadbarrier);
}
bool LoadBarrierNode::is_dominator(PhaseIdealLoop* phase, bool linear_only, Node *d, Node *n) {
if (phase != NULL) {
return phase->is_dominator(d, n);
}
for (int i = 0; i < 10 && n != NULL; i++) {
n = IfNode::up_one_dom(n, linear_only);
if (n == d) {
return true;
}
}
return false;
}
LoadBarrierNode* LoadBarrierNode::has_dominating_barrier(PhaseIdealLoop* phase, bool linear_only, bool look_for_similar) {
if (is_weak()) {
// Weak barriers can't be eliminated
return NULL;
}
Node* val = in(LoadBarrierNode::Oop);
if (in(Similar)->is_Proj() && in(Similar)->in(0)->is_LoadBarrier()) {
LoadBarrierNode* lb = in(Similar)->in(0)->as_LoadBarrier();
assert(lb->in(Address) == in(Address), "");
// Load barrier on Similar edge dominates so if it now has the Oop field it can replace this barrier.
if (lb->in(Oop) == in(Oop)) {
return lb;
}
// Follow chain of load barrier through Similar edges
while (!lb->in(Similar)->is_top()) {
lb = lb->in(Similar)->in(0)->as_LoadBarrier();
assert(lb->in(Address) == in(Address), "");
}
if (lb != in(Similar)->in(0)) {
return lb;
}
}
for (DUIterator_Fast imax, i = val->fast_outs(imax); i < imax; i++) {
Node* u = val->fast_out(i);
if (u != this && u->is_LoadBarrier() && u->in(Oop) == val && u->as_LoadBarrier()->has_true_uses()) {
Node* this_ctrl = in(LoadBarrierNode::Control);
Node* other_ctrl = u->in(LoadBarrierNode::Control);
if (is_dominator(phase, linear_only, other_ctrl, this_ctrl)) {
return u->as_LoadBarrier();
}
}
}
if (can_be_eliminated()) {
return NULL;
}
if (!look_for_similar) {
return NULL;
}
Node* addr = in(LoadBarrierNode::Address);
for (DUIterator_Fast imax, i = addr->fast_outs(imax); i < imax; i++) {
Node* u = addr->fast_out(i);
if (u != this && u->is_LoadBarrier() && u->as_LoadBarrier()->has_true_uses()) {
Node* this_ctrl = in(LoadBarrierNode::Control);
Node* other_ctrl = u->in(LoadBarrierNode::Control);
if (is_dominator(phase, linear_only, other_ctrl, this_ctrl)) {
ResourceMark rm;
Unique_Node_List wq;
wq.push(in(LoadBarrierNode::Control));
bool ok = true;
bool dom_found = false;
for (uint next = 0; next < wq.size(); ++next) {
Node *n = wq.at(next);
if (n->is_top()) {
return NULL;
}
assert(n->is_CFG(), "");
if (n->is_SafePoint()) {
ok = false;
break;
}
if (n == u) {
dom_found = true;
continue;
}
if (n->is_Region()) {
for (uint i = 1; i < n->req(); i++) {
Node* m = n->in(i);
if (m != NULL) {
wq.push(m);
}
}
} else {
Node* m = n->in(0);
if (m != NULL) {
wq.push(m);
}
}
}
if (ok) {
assert(dom_found, "");
return u->as_LoadBarrier();
}
break;
}
}
}
return NULL;
}
void LoadBarrierNode::push_dominated_barriers(PhaseIterGVN* igvn) const {
// Change to that barrier may affect a dominated barrier so re-push those
assert(!is_weak(), "sanity");
Node* val = in(LoadBarrierNode::Oop);
for (DUIterator_Fast imax, i = val->fast_outs(imax); i < imax; i++) {
Node* u = val->fast_out(i);
if (u != this && u->is_LoadBarrier() && u->in(Oop) == val) {
Node* this_ctrl = in(Control);
Node* other_ctrl = u->in(Control);
if (is_dominator(NULL, false, this_ctrl, other_ctrl)) {
igvn->_worklist.push(u);
}
}
Node* addr = in(LoadBarrierNode::Address);
for (DUIterator_Fast imax, i = addr->fast_outs(imax); i < imax; i++) {
Node* u = addr->fast_out(i);
if (u != this && u->is_LoadBarrier() && u->in(Similar)->is_top()) {
Node* this_ctrl = in(Control);
Node* other_ctrl = u->in(Control);
if (is_dominator(NULL, false, this_ctrl, other_ctrl)) {
igvn->_worklist.push(u);
}
}
}
}
}
Node *LoadBarrierNode::Identity(PhaseGVN *phase) {
LoadBarrierNode* dominating_barrier = has_dominating_barrier(NULL, true, false);
if (dominating_barrier != NULL) {
assert(!is_weak(), "Weak barriers cant be eliminated");
assert(dominating_barrier->in(Oop) == in(Oop), "");
return dominating_barrier;
}
return this;
}
Node *LoadBarrierNode::Ideal(PhaseGVN *phase, bool can_reshape) {
if (remove_dead_region(phase, can_reshape)) {
return this;
}
Node *val = in(Oop);
Node *mem = in(Memory);
Node *ctrl = in(Control);
assert(val->Opcode() != Op_LoadN, "");
assert(val->Opcode() != Op_DecodeN, "");
if (mem->is_MergeMem()) {
Node *new_mem = mem->as_MergeMem()->memory_at(Compile::AliasIdxRaw);
set_req(Memory, new_mem);
if (mem->outcnt() == 0 && can_reshape) {
phase->is_IterGVN()->_worklist.push(mem);
}
return this;
}
LoadBarrierNode *dominating_barrier = NULL;
if (!is_weak()) {
dominating_barrier = has_dominating_barrier(NULL, !can_reshape, !phase->C->major_progress());
if (dominating_barrier != NULL && dominating_barrier->in(Oop) != in(Oop)) {
assert(in(Address) == dominating_barrier->in(Address), "");
set_req(Similar, dominating_barrier->proj_out(Oop));
return this;
}
}
bool eliminate = can_reshape && (dominating_barrier != NULL || !has_true_uses());
if (eliminate) {
if (can_reshape) {
PhaseIterGVN* igvn = phase->is_IterGVN();
Node* out_ctrl = proj_out_or_null(Control);
Node* out_res = proj_out_or_null(Oop);
if (out_ctrl != NULL) {
igvn->replace_node(out_ctrl, ctrl);
}
// That transformation may cause the Similar edge on the load barrier to be invalid
fix_similar_in_uses(igvn);
if (out_res != NULL) {
if (dominating_barrier != NULL) {
assert(!is_weak(), "Sanity");
igvn->replace_node(out_res, dominating_barrier->proj_out(Oop));
} else {
igvn->replace_node(out_res, val);
}
}
}
return new ConINode(TypeInt::ZERO);
}
// If the Similar edge is no longer a load barrier, clear it
Node* similar = in(Similar);
if (!similar->is_top() && !(similar->is_Proj() && similar->in(0)->is_LoadBarrier())) {
set_req(Similar, phase->C->top());
return this;
}
if (can_reshape && !is_weak()) {
// If this barrier is linked through the Similar edge by a
// dominated barrier and both barriers have the same Oop field,
// the dominated barrier can go away, so push it for reprocessing.
// We also want to avoid a barrier to depend on another dominating
// barrier through its Similar edge that itself depend on another
// barrier through its Similar edge and rather have the first
// depend on the third.
PhaseIterGVN* igvn = phase->is_IterGVN();
Node* out_res = proj_out(Oop);
for (DUIterator_Fast imax, i = out_res->fast_outs(imax); i < imax; i++) {
Node* u = out_res->fast_out(i);
if (u->is_LoadBarrier() && u->in(Similar) == out_res &&
(u->in(Oop) == val || !u->in(Similar)->is_top())) {
assert(!u->as_LoadBarrier()->is_weak(), "Sanity");
igvn->_worklist.push(u);
}
}
push_dominated_barriers(igvn);
}
return NULL;
}
uint LoadBarrierNode::match_edge(uint idx) const {
ShouldNotReachHere();
return 0;
}
void LoadBarrierNode::fix_similar_in_uses(PhaseIterGVN* igvn) {
Node* out_res = proj_out_or_null(Oop);
if (out_res == NULL) {
return;
}
for (DUIterator_Fast imax, i = out_res->fast_outs(imax); i < imax; i++) {
Node* u = out_res->fast_out(i);
if (u->is_LoadBarrier() && u->in(Similar) == out_res) {
igvn->replace_input_of(u, Similar, igvn->C->top());
--i;
--imax;
}
}
}
bool LoadBarrierNode::has_true_uses() const {
Node* out_res = proj_out_or_null(Oop);
if (out_res != NULL) {
for (DUIterator_Fast imax, i = out_res->fast_outs(imax); i < imax; i++) {
Node *u = out_res->fast_out(i);
if (!u->is_LoadBarrier() || u->in(Similar) != out_res) {
return true;
}
}
}
return false;
}
static bool barrier_needed(C2Access& access) {
return ZBarrierSet::barrier_needed(access.decorators(), access.type());
}
Node* ZBarrierSetC2::load_at_resolved(C2Access& access, const Type* val_type) const {
Node* p = BarrierSetC2::load_at_resolved(access, val_type);
if (!barrier_needed(access)) {
return p;
}
bool weak = (access.decorators() & ON_WEAK_OOP_REF) != 0;
if (p->isa_Load()) {
load_set_barrier(p->as_Load(), weak);
}
return p;
}
Node* ZBarrierSetC2::atomic_cmpxchg_val_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
Node* new_val, const Type* val_type) const {
Node* result = BarrierSetC2::atomic_cmpxchg_val_at_resolved(access, expected_val, new_val, val_type);
LoadStoreNode* lsn = result->as_LoadStore();
if (barrier_needed(access)) {
lsn->set_has_barrier();
}
return lsn;
}
Node* ZBarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
Node* new_val, const Type* value_type) const {
Node* result = BarrierSetC2::atomic_cmpxchg_bool_at_resolved(access, expected_val, new_val, value_type);
LoadStoreNode* lsn = result->as_LoadStore();
if (barrier_needed(access)) {
lsn->set_has_barrier();
}
return lsn;
}
Node* ZBarrierSetC2::atomic_xchg_at_resolved(C2AtomicParseAccess& access, Node* new_val, const Type* val_type) const {
Node* result = BarrierSetC2::atomic_xchg_at_resolved(access, new_val, val_type);
LoadStoreNode* lsn = result->as_LoadStore();
if (barrier_needed(access)) {
lsn->set_has_barrier();
}
return lsn;
}
// == Macro Expansion ==
// Optimized, low spill, loadbarrier variant using stub specialized on register used
void ZBarrierSetC2::expand_loadbarrier_node(PhaseMacroExpand* phase, LoadBarrierNode* barrier) const {
PhaseIterGVN &igvn = phase->igvn();
float unlikely = PROB_UNLIKELY(0.999);
Node* in_ctrl = barrier->in(LoadBarrierNode::Control);
Node* in_mem = barrier->in(LoadBarrierNode::Memory);
Node* in_val = barrier->in(LoadBarrierNode::Oop);
Node* in_adr = barrier->in(LoadBarrierNode::Address);
Node* out_ctrl = barrier->proj_out(LoadBarrierNode::Control);
Node* out_res = barrier->proj_out(LoadBarrierNode::Oop);
assert(barrier->in(LoadBarrierNode::Oop) != NULL, "oop to loadbarrier node cannot be null");
Node* jthread = igvn.transform(new ThreadLocalNode());
Node* adr = phase->basic_plus_adr(jthread, in_bytes(ZThreadLocalData::address_bad_mask_offset()));
Node* bad_mask = igvn.transform(LoadNode::make(igvn, in_ctrl, in_mem, adr,
TypeRawPtr::BOTTOM, TypeX_X, TypeX_X->basic_type(),
MemNode::unordered));
Node* cast = igvn.transform(new CastP2XNode(in_ctrl, in_val));
Node* obj_masked = igvn.transform(new AndXNode(cast, bad_mask));
Node* cmp = igvn.transform(new CmpXNode(obj_masked, igvn.zerocon(TypeX_X->basic_type())));
Node *bol = igvn.transform(new BoolNode(cmp, BoolTest::ne))->as_Bool();
IfNode* iff = igvn.transform(new IfNode(in_ctrl, bol, unlikely, COUNT_UNKNOWN))->as_If();
Node* then = igvn.transform(new IfTrueNode(iff));
Node* elsen = igvn.transform(new IfFalseNode(iff));
Node* new_loadp = igvn.transform(new LoadBarrierSlowRegNode(then, in_adr, in_val,
(const TypePtr*) in_val->bottom_type(), barrier->is_weak()));
// Create the final region/phi pair to converge cntl/data paths to downstream code
Node* result_region = igvn.transform(new RegionNode(3));
result_region->set_req(1, then);
result_region->set_req(2, elsen);
Node* result_phi = igvn.transform(new PhiNode(result_region, TypeInstPtr::BOTTOM));
result_phi->set_req(1, new_loadp);
result_phi->set_req(2, barrier->in(LoadBarrierNode::Oop));
igvn.replace_node(out_ctrl, result_region);
igvn.replace_node(out_res, result_phi);
assert(barrier->outcnt() == 0,"LoadBarrier macro node has non-null outputs after expansion!");
igvn.remove_dead_node(barrier);
igvn.remove_dead_node(out_ctrl);
igvn.remove_dead_node(out_res);
assert(is_gc_barrier_node(result_phi), "sanity");
assert(step_over_gc_barrier(result_phi) == in_val, "sanity");
phase->C->print_method(PHASE_BARRIER_EXPANSION, 4, barrier->_idx);
}
bool ZBarrierSetC2::expand_barriers(Compile* C, PhaseIterGVN& igvn) const {
ZBarrierSetC2State* s = state();
if (s->load_barrier_count() > 0) {
PhaseMacroExpand macro(igvn);
int skipped = 0;
while (s->load_barrier_count() > skipped) {
int load_barrier_count = s->load_barrier_count();
LoadBarrierNode * n = s->load_barrier_node(load_barrier_count-1-skipped);
if (igvn.type(n) == Type::TOP || (n->in(0) != NULL && n->in(0)->is_top())) {
// Node is unreachable, so don't try to expand it
s->remove_load_barrier_node(n);
continue;
}
if (!n->can_be_eliminated()) {
skipped++;
continue;
}
expand_loadbarrier_node(¯o, n);
assert(s->load_barrier_count() < load_barrier_count, "must have deleted a node from load barrier list");
if (C->failing()) {
return true;
}
}
while (s->load_barrier_count() > 0) {
int load_barrier_count = s->load_barrier_count();
LoadBarrierNode* n = s->load_barrier_node(load_barrier_count - 1);
assert(!(igvn.type(n) == Type::TOP || (n->in(0) != NULL && n->in(0)->is_top())), "should have been processed already");
assert(!n->can_be_eliminated(), "should have been processed already");
expand_loadbarrier_node(¯o, n);
assert(s->load_barrier_count() < load_barrier_count, "must have deleted a node from load barrier list");
if (C->failing()) {
return true;
}
}
igvn.set_delay_transform(false);
igvn.optimize();
if (C->failing()) {
return true;
}
}
return false;
}
Node* ZBarrierSetC2::step_over_gc_barrier(Node* c) const {
Node* node = c;
// 1. This step follows potential oop projections of a load barrier before expansion
if (node->is_Proj()) {
node = node->in(0);
}
// 2. This step checks for unexpanded load barriers
if (node->is_LoadBarrier()) {
return node->in(LoadBarrierNode::Oop);
}
// 3. This step checks for the phi corresponding to an optimized load barrier expansion
if (node->is_Phi()) {
PhiNode* phi = node->as_Phi();
Node* n = phi->in(1);
if (n != NULL && n->is_LoadBarrierSlowReg()) {
assert(c == node, "projections from step 1 should only be seen before macro expansion");
return phi->in(2);
}
}
return c;
}
Node* ZBarrierSetC2::step_over_gc_barrier_ctrl(Node* c) const {
Node* node = c;
// 1. This step follows potential ctrl projections of a load barrier before expansion
if (node->is_Proj()) {
node = node->in(0);
}
// 2. This step checks for unexpanded load barriers
if (node->is_LoadBarrier()) {
return node->in(LoadBarrierNode::Control);
}
return c;
}
bool ZBarrierSetC2::array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type, bool is_clone, ArrayCopyPhase phase) const {
return type == T_OBJECT || type == T_ARRAY;
}
bool ZBarrierSetC2::final_graph_reshaping(Compile* compile, Node* n, uint opcode) const {
switch (opcode) {
case Op_LoadBarrier:
assert(0, "There should be no load barriers left");
case Op_ZGetAndSetP:
case Op_ZCompareAndExchangeP:
case Op_ZCompareAndSwapP:
case Op_ZWeakCompareAndSwapP:
#ifdef ASSERT
if (VerifyOptoOopOffsets) {
MemNode *mem = n->as_Mem();
// Check to see if address types have grounded out somehow.
const TypeInstPtr *tp = mem->in(MemNode::Address)->bottom_type()->isa_instptr();
ciInstanceKlass *k = tp->klass()->as_instance_klass();
bool oop_offset_is_sane = k->contains_field_offset(tp->offset());
assert(!tp || oop_offset_is_sane, "");
}
#endif
return true;
default:
return false;
}
}
bool ZBarrierSetC2::matcher_find_shared_visit(Matcher* matcher, Matcher::MStack& mstack, Node* n, uint opcode, bool& mem_op, int& mem_addr_idx) const {
switch(opcode) {
case Op_CallLeaf:
if (n->as_Call()->entry_point() == ZBarrierSetRuntime::load_barrier_on_oop_field_preloaded_addr() ||
n->as_Call()->entry_point() == ZBarrierSetRuntime::load_barrier_on_weak_oop_field_preloaded_addr()) {
mem_op = true;
mem_addr_idx = TypeFunc::Parms + 1;
return true;
}
return false;
default:
return false;
}
}
bool ZBarrierSetC2::matcher_find_shared_post_visit(Matcher* matcher, Node* n, uint opcode) const {
switch(opcode) {
case Op_ZCompareAndExchangeP:
case Op_ZCompareAndSwapP:
case Op_ZWeakCompareAndSwapP: {
Node *mem = n->in(MemNode::Address);
Node *keepalive = n->in(5);
Node *pair1 = new BinaryNode(mem, keepalive);
Node *newval = n->in(MemNode::ValueIn);
Node *oldval = n->in(LoadStoreConditionalNode::ExpectedIn);
Node *pair2 = new BinaryNode(oldval, newval);
n->set_req(MemNode::Address, pair1);
n->set_req(MemNode::ValueIn, pair2);
n->del_req(5);
n->del_req(LoadStoreConditionalNode::ExpectedIn);
return true;
}
case Op_ZGetAndSetP: {
Node *keepalive = n->in(4);
Node *newval = n->in(MemNode::ValueIn);
Node *pair = new BinaryNode(newval, keepalive);
n->set_req(MemNode::ValueIn, pair);
n->del_req(4);
return true;
}
default:
return false;
}
}
// == Verification ==
#ifdef ASSERT
static bool look_for_barrier(Node* n, bool post_parse, VectorSet& visited) {
if (visited.test_set(n->_idx)) {
return true;
}
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
Node* u = n->fast_out(i);
if (u->is_LoadBarrier()) {
} else if ((u->is_Phi() || u->is_CMove()) && !post_parse) {
if (!look_for_barrier(u, post_parse, visited)) {
return false;
}
} else if (u->Opcode() == Op_EncodeP || u->Opcode() == Op_DecodeN) {
if (!look_for_barrier(u, post_parse, visited)) {
return false;
}
} else if (u->Opcode() != Op_SCMemProj) {
tty->print("bad use"); u->dump();
return false;
}
}
return true;
}
void ZBarrierSetC2::verify_gc_barriers(Compile* compile, CompilePhase phase) const {
switch(phase) {
case BarrierSetC2::BeforeOptimize:
case BarrierSetC2::BeforeLateInsertion:
assert(state()->load_barrier_count() == 0, "No barriers inserted yet");
break;
case BarrierSetC2::BeforeMacroExpand:
// Barrier placement should be set by now.
verify_gc_barriers(false /*post_parse*/);
break;
case BarrierSetC2::BeforeCodeGen:
// Barriers has been fully expanded.
assert(state()->load_barrier_count() == 0, "No more macro barriers");
break;
default:
assert(0, "Phase without verification");
}
}
// post_parse implies that there might be load barriers without uses after parsing
// That only applies when adding barriers at parse time.
void ZBarrierSetC2::verify_gc_barriers(bool post_parse) const {
ZBarrierSetC2State* s = state();
Compile* C = Compile::current();
ResourceMark rm;
VectorSet visited(Thread::current()->resource_area());
for (int i = 0; i < s->load_barrier_count(); i++) {
LoadBarrierNode* n = s->load_barrier_node(i);
// The dominating barrier on the same address if it exists and
// this barrier must not be applied on the value from the same
// load otherwise the value is not reloaded before it's used the
// second time.
assert(n->in(LoadBarrierNode::Similar)->is_top() ||
(n->in(LoadBarrierNode::Similar)->in(0)->is_LoadBarrier() &&
n->in(LoadBarrierNode::Similar)->in(0)->in(LoadBarrierNode::Address) == n->in(LoadBarrierNode::Address) &&
n->in(LoadBarrierNode::Similar)->in(0)->in(LoadBarrierNode::Oop) != n->in(LoadBarrierNode::Oop)),
"broken similar edge");
assert(n->as_LoadBarrier()->has_true_uses(),
"found unneeded load barrier");
// Several load barrier nodes chained through their Similar edge
// break the code that remove the barriers in final graph reshape.
assert(n->in(LoadBarrierNode::Similar)->is_top() ||
(n->in(LoadBarrierNode::Similar)->in(0)->is_LoadBarrier() &&
n->in(LoadBarrierNode::Similar)->in(0)->in(LoadBarrierNode::Similar)->is_top()),
"chain of Similar load barriers");
if (!n->in(LoadBarrierNode::Similar)->is_top()) {
ResourceMark rm;
Unique_Node_List wq;
Node* other = n->in(LoadBarrierNode::Similar)->in(0);
wq.push(n);
for (uint next = 0; next < wq.size(); ++next) {
Node *nn = wq.at(next);
assert(nn->is_CFG(), "");
assert(!nn->is_SafePoint(), "");
if (nn == other) {
continue;
}
if (nn->is_Region()) {
for (uint i = 1; i < nn->req(); i++) {
Node* m = nn->in(i);
if (m != NULL) {
wq.push(m);
}
}
} else {
Node* m = nn->in(0);
if (m != NULL) {
wq.push(m);
}
}
}
}
}
}
#endif // end verification code
static void call_catch_cleanup_one(PhaseIdealLoop* phase, LoadNode* load, Node* ctrl);
// This code is cloning all uses of a load that is between a call and the catch blocks,
// to each use.
static bool fixup_uses_in_catch(PhaseIdealLoop *phase, Node *start_ctrl, Node *node) {
if (!phase->has_ctrl(node)) {
// This node is floating - doesn't need to be cloned.
assert(node != start_ctrl, "check");
return false;
}
Node* ctrl = phase->get_ctrl(node);
if (ctrl != start_ctrl) {
// We are in a successor block - the node is ok.
return false; // Unwind
}
// Process successor nodes
int outcnt = node->outcnt();
for (int i = 0; i < outcnt; i++) {
Node* n = node->raw_out(0);
assert(!n->is_LoadBarrier(), "Sanity");
// Calling recursively, visiting leafs first
fixup_uses_in_catch(phase, start_ctrl, n);
}
// Now all successors are outside
// - Clone this node to both successors
int no_succs = node->outcnt();
assert(!node->is_Store(), "Stores not expected here");
// In some very rare cases a load that doesn't need a barrier will end up here
// Treat it as a LoadP and the insertion of phis will be done correctly.
if (node->is_Load()) {
call_catch_cleanup_one(phase, node->as_Load(), phase->get_ctrl(node));
} else {
for (DUIterator_Fast jmax, i = node->fast_outs(jmax); i < jmax; i++) {
Node* use = node->fast_out(i);
Node* clone = node->clone();
assert(clone->outcnt() == 0, "");
assert(use->find_edge(node) != -1, "check");
phase->igvn().rehash_node_delayed(use);
use->replace_edge(node, clone);
Node* new_ctrl;
if (use->is_block_start()) {
new_ctrl = use;
} else if (use->is_CFG()) {
new_ctrl = use->in(0);
assert (new_ctrl != NULL, "");
} else {
new_ctrl = phase->get_ctrl(use);
}
phase->set_ctrl(clone, new_ctrl);
if (phase->C->directive()->ZTraceLoadBarriersOption) tty->print_cr(" Clone op %i as %i to control %i", node->_idx, clone->_idx, new_ctrl->_idx);
phase->igvn().register_new_node_with_optimizer(clone);
--i, --jmax;
}
assert(node->outcnt() == 0, "must be empty now");
// Node node is dead.
phase->igvn().remove_dead_node(node);
}
return true; // unwind - return if a use was processed
}
// Clone a load to a specific catch_proj
static Node* clone_load_to_catchproj(PhaseIdealLoop* phase, Node* load, Node* catch_proj) {
Node* cloned_load = load->clone();
cloned_load->set_req(0, catch_proj); // set explicit control
phase->set_ctrl(cloned_load, catch_proj); // update
if (phase->C->directive()->ZTraceLoadBarriersOption) tty->print_cr(" Clone LOAD %i as %i to control %i", load->_idx, cloned_load->_idx, catch_proj->_idx);
phase->igvn().register_new_node_with_optimizer(cloned_load);
return cloned_load;
}
static Node* get_dominating_region(PhaseIdealLoop* phase, Node* node, Node* stop) {
Node* region = node;
while (!region->isa_Region()) {
Node *up = phase->idom(region);
assert(up != region, "Must not loop");
assert(up != stop, "Must not find original control");
region = up;
}
return region;
}
// Clone this load to each catch block
static void call_catch_cleanup_one(PhaseIdealLoop* phase, LoadNode* load, Node* ctrl) {
bool trace = phase->C->directive()->ZTraceLoadBarriersOption;
phase->igvn().set_delay_transform(true);
// Verify pre conditions
assert(ctrl->isa_Proj() && ctrl->in(0)->isa_Call(), "Must be a call proj");
assert(ctrl->raw_out(0)->isa_Catch(), "Must be a catch");
if (ctrl->raw_out(0)->isa_Catch()->outcnt() == 1) {
if (trace) tty->print_cr("Cleaning up catch: Skipping load %i, call with single catch", load->_idx);
return;
}
// Process the loads successor nodes - if any is between
// the call and the catch blocks, they need to be cloned to.
// This is done recursively
int outcnt = load->outcnt();
uint index = 0;
for (int i = 0; i < outcnt; i++) {
if (index < load->outcnt()) {
Node *n = load->raw_out(index);
assert(!n->is_LoadBarrier(), "Sanity");
if (!fixup_uses_in_catch(phase, ctrl, n)) {
// if no successor was cloned, progress to next out.
index++;
}
}
}
// Now all the loads uses has been cloned down
// Only thing left is to clone the loads, but they must end up
// first in the catch blocks.
// We clone the loads oo the catch blocks only when needed.
// An array is used to map the catch blocks to each lazily cloned load.
// In that way no extra unnecessary loads are cloned.
// Any use dominated by original block must have an phi and a region added
Node* catch_node = ctrl->raw_out(0);
int number_of_catch_projs = catch_node->outcnt();
Node** proj_to_load_mapping = NEW_RESOURCE_ARRAY(Node*, number_of_catch_projs);
Copy::zero_to_bytes(proj_to_load_mapping, sizeof(Node*) * number_of_catch_projs);
// The phi_map is used to keep track of where phis have already been inserted
int phi_map_len = phase->C->unique();
Node** phi_map = NEW_RESOURCE_ARRAY(Node*, phi_map_len);
Copy::zero_to_bytes(phi_map, sizeof(Node*) * phi_map_len);
for (unsigned int i = 0; i < load->outcnt(); i++) {
Node* load_use_control = NULL;
Node* load_use = load->raw_out(i);
if (phase->has_ctrl(load_use)) {
load_use_control = phase->get_ctrl(load_use);
} else {
load_use_control = load_use->in(0);
}
assert(load_use_control != NULL, "sanity");
if (trace) tty->print_cr(" Handling use: %i, with control: %i", load_use->_idx, load_use_control->_idx);
// Some times the loads use is a phi. For them we need to determine from which catch block
// the use is defined.
bool load_use_is_phi = false;
unsigned int load_use_phi_index = 0;
Node* phi_ctrl = NULL;
if (load_use->is_Phi()) {
// Find phi input that matches load
for (unsigned int u = 1; u < load_use->req(); u++) {
if (load_use->in(u) == load) {
load_use_is_phi = true;
load_use_phi_index = u;
assert(load_use->in(0)->is_Region(), "Region or broken");
phi_ctrl = load_use->in(0)->in(u);
assert(phi_ctrl->is_CFG(), "check");
assert(phi_ctrl != load, "check");
break;
}
}
assert(load_use_is_phi, "must find");
assert(load_use_phi_index > 0, "sanity");
}
// For each load use, see which catch projs dominates, create load clone lazily and reconnect
bool found_dominating_catchproj = false;
for (int c = 0; c < number_of_catch_projs; c++) {
Node* catchproj = catch_node->raw_out(c);
assert(catchproj != NULL && catchproj->isa_CatchProj(), "Sanity");
if (!phase->is_dominator(catchproj, load_use_control)) {
if (load_use_is_phi && phase->is_dominator(catchproj, phi_ctrl)) {
// The loads use is local to the catchproj.
// fall out and replace load with catch-local load clone.
} else {
continue;
}
}
assert(!found_dominating_catchproj, "Max one should match");
// Clone loads to catch projs
Node* load_clone = proj_to_load_mapping[c];
if (load_clone == NULL) {
load_clone = clone_load_to_catchproj(phase, load, catchproj);
proj_to_load_mapping[c] = load_clone;
}
phase->igvn().rehash_node_delayed(load_use);
if (load_use_is_phi) {
// phis are special - the load is defined from a specific control flow
load_use->set_req(load_use_phi_index, load_clone);
} else {
// Multipe edges can be replaced at once - on calls for example
load_use->replace_edge(load, load_clone);
}
--i; // more than one edge can have been removed, but the next is in later iterations
// We could break the for-loop after finding a dominating match.
// But keep iterating to catch any bad idom early.
found_dominating_catchproj = true;
}
// We found no single catchproj that dominated the use - The use is at a point after
// where control flow from multiple catch projs have merged. We will have to create
// phi nodes before the use and tie the output from the cloned loads together. It
// can be a single phi or a number of chained phis, depending on control flow
if (!found_dominating_catchproj) {
// Use phi-control if use is a phi
if (load_use_is_phi) {
load_use_control = phi_ctrl;
}
assert(phase->is_dominator(ctrl, load_use_control), "Common use but no dominator");
// Clone a load on all paths
for (int c = 0; c < number_of_catch_projs; c++) {
Node* catchproj = catch_node->raw_out(c);
Node* load_clone = proj_to_load_mapping[c];
if (load_clone == NULL) {
load_clone = clone_load_to_catchproj(phase, load, catchproj);
proj_to_load_mapping[c] = load_clone;
}
}
// Move up dominator tree from use until dom front is reached
Node* next_region = get_dominating_region(phase, load_use_control, ctrl);
while (phase->idom(next_region) != catch_node) {
next_region = phase->idom(next_region);
if (trace) tty->print_cr("Moving up idom to region ctrl %i", next_region->_idx);
}
assert(phase->is_dominator(catch_node, next_region), "Sanity");
// Create or reuse phi node that collect all cloned loads and feed it to the use.
Node* test_phi = phi_map[next_region->_idx];
if ((test_phi != NULL) && test_phi->is_Phi()) {
// Reuse an already created phi
if (trace) tty->print_cr(" Using cached Phi %i on load_use %i", test_phi->_idx, load_use->_idx);
phase->igvn().rehash_node_delayed(load_use);
load_use->replace_edge(load, test_phi);
// Now this use is done
} else {
// Otherwise we need to create one or more phis
PhiNode* next_phi = new PhiNode(next_region, load->type());
phi_map[next_region->_idx] = next_phi; // cache new phi
phase->igvn().rehash_node_delayed(load_use);
load_use->replace_edge(load, next_phi);
int dominators_of_region = 0;
do {
// New phi, connect to region and add all loads as in.
Node* region = next_region;
assert(region->isa_Region() && region->req() > 2, "Catch dead region nodes");
PhiNode* new_phi = next_phi;
if (trace) tty->print_cr("Created Phi %i on load %i with control %i", new_phi->_idx, load->_idx, region->_idx);
// Need to add all cloned loads to the phi, taking care that the right path is matched
dominators_of_region = 0; // reset for new region
for (unsigned int reg_i = 1; reg_i < region->req(); reg_i++) {
Node* region_pred = region->in(reg_i);
assert(region_pred->is_CFG(), "check");
bool pred_has_dominator = false;
for (int c = 0; c < number_of_catch_projs; c++) {
Node* catchproj = catch_node->raw_out(c);
if (phase->is_dominator(catchproj, region_pred)) {
new_phi->set_req(reg_i, proj_to_load_mapping[c]);
if (trace) tty->print_cr(" - Phi in(%i) set to load %i", reg_i, proj_to_load_mapping[c]->_idx);
pred_has_dominator = true;
dominators_of_region++;
break;
}
}
// Sometimes we need to chain several phis.
if (!pred_has_dominator) {
assert(dominators_of_region <= 1, "More than one region can't require extra phi");
if (trace) tty->print_cr(" - Region %i pred %i not dominated by catch proj", region->_idx, region_pred->_idx);
// Continue search on on this region_pred
// - walk up to next region
// - create a new phi and connect to first new_phi
next_region = get_dominating_region(phase, region_pred, ctrl);
// Lookup if there already is a phi, create a new otherwise
Node* test_phi = phi_map[next_region->_idx];
if ((test_phi != NULL) && test_phi->is_Phi()) {
next_phi = test_phi->isa_Phi();
dominators_of_region++; // record that a match was found and that we are done
if (trace) tty->print_cr(" Using cached phi Phi %i on control %i", next_phi->_idx, next_region->_idx);
} else {
next_phi = new PhiNode(next_region, load->type());
phi_map[next_region->_idx] = next_phi;
}
new_phi->set_req(reg_i, next_phi);
}
}
new_phi->set_req(0, region);
phase->igvn().register_new_node_with_optimizer(new_phi);
phase->set_ctrl(new_phi, region);
assert(dominators_of_region != 0, "Must have found one this iteration");
} while (dominators_of_region == 1);
}
--i;
}
} // end of loop over uses
assert(load->outcnt() == 0, "All uses should be handled");
phase->igvn().remove_dead_node(load);
phase->C->print_method(PHASE_CALL_CATCH_CLEANUP, 4, load->_idx);
// Now we should be home
phase->igvn().set_delay_transform(false);
}
// Sort out the loads that are between a call ant its catch blocks
static void process_catch_cleanup_candidate(PhaseIdealLoop* phase, LoadNode* load) {
bool trace = phase->C->directive()->ZTraceLoadBarriersOption;
Node* ctrl = phase->get_ctrl(load);
if (!ctrl->is_Proj() || (ctrl->in(0) == NULL) || !ctrl->in(0)->isa_Call()) {
return;
}
Node* catch_node = ctrl->isa_Proj()->raw_out(0);
if (catch_node->is_Catch()) {
if (catch_node->outcnt() > 1) {
call_catch_cleanup_one(phase, load, ctrl);
} else {
if (trace) tty->print_cr("Call catch cleanup with only one catch: load %i ", load->_idx);
}
}
}
void ZBarrierSetC2::barrier_insertion_phase(Compile* C, PhaseIterGVN& igvn) const {
PhaseIdealLoop::optimize(igvn, LoopOptsZBarrierInsertion);
if (C->failing()) return;
}
bool ZBarrierSetC2::optimize_loops(PhaseIdealLoop* phase, LoopOptsMode mode, VectorSet& visited, Node_Stack& nstack, Node_List& worklist) const {
if (mode == LoopOptsZBarrierInsertion) {
// First make sure all loads between call and catch are moved to the catch block
clean_catch_blocks(phase);
// Then expand barriers on all loads
insert_load_barriers(phase);
// Handle all Unsafe that need barriers.
insert_barriers_on_unsafe(phase);
phase->C->clear_major_progress();
return true;
} else {
return false;
}
}
static bool can_simplify_cas(LoadStoreNode* node) {
if (node->isa_LoadStoreConditional()) {
Node *expected_in = node->as_LoadStoreConditional()->in(LoadStoreConditionalNode::ExpectedIn);
return (expected_in->get_ptr_type() == TypePtr::NULL_PTR);
} else {
return false;
}
}
static void insert_barrier_before_unsafe(PhaseIdealLoop* phase, LoadStoreNode* old_node) {
Compile *C = phase->C;
PhaseIterGVN &igvn = phase->igvn();
LoadStoreNode* zclone = NULL;
Node *in_ctrl = old_node->in(MemNode::Control);
Node *in_mem = old_node->in(MemNode::Memory);
Node *in_adr = old_node->in(MemNode::Address);
Node *in_val = old_node->in(MemNode::ValueIn);
const TypePtr *adr_type = old_node->adr_type();
const TypePtr* load_type = TypeOopPtr::BOTTOM; // The type for the load we are adding
switch (old_node->Opcode()) {
case Op_CompareAndExchangeP: {
zclone = new ZCompareAndExchangePNode(in_ctrl, in_mem, in_adr, in_val, old_node->in(LoadStoreConditionalNode::ExpectedIn),
adr_type, old_node->get_ptr_type(), ((CompareAndExchangeNode*)old_node)->order());
load_type = old_node->bottom_type()->is_ptr();
break;
}
case Op_WeakCompareAndSwapP: {
if (can_simplify_cas(old_node)) {
break;
}
zclone = new ZWeakCompareAndSwapPNode(in_ctrl, in_mem, in_adr, in_val, old_node->in(LoadStoreConditionalNode::ExpectedIn),
((CompareAndSwapNode*)old_node)->order());
adr_type = TypePtr::BOTTOM;
break;
}
case Op_CompareAndSwapP: {
if (can_simplify_cas(old_node)) {
break;
}
zclone = new ZCompareAndSwapPNode(in_ctrl, in_mem, in_adr, in_val, old_node->in(LoadStoreConditionalNode::ExpectedIn),
((CompareAndSwapNode*)old_node)->order());
adr_type = TypePtr::BOTTOM;
break;
}
case Op_GetAndSetP: {
zclone = new ZGetAndSetPNode(in_ctrl, in_mem, in_adr, in_val, old_node->adr_type(), old_node->get_ptr_type());
load_type = old_node->bottom_type()->is_ptr();
break;
}
}
if (zclone != NULL) {
igvn.register_new_node_with_optimizer(zclone, old_node);
// Make load
LoadPNode *load = new LoadPNode(NULL, in_mem, in_adr, adr_type, load_type, MemNode::unordered,
LoadNode::DependsOnlyOnTest);
load_set_expanded_barrier(load);
igvn.register_new_node_with_optimizer(load);
igvn.replace_node(old_node, zclone);
Node *barrier = new LoadBarrierNode(C, NULL, in_mem, load, in_adr, false /* weak */);
Node *barrier_val = new ProjNode(barrier, LoadBarrierNode::Oop);
Node *barrier_ctrl = new ProjNode(barrier, LoadBarrierNode::Control);
igvn.register_new_node_with_optimizer(barrier);
igvn.register_new_node_with_optimizer(barrier_val);
igvn.register_new_node_with_optimizer(barrier_ctrl);
// loop over all of in_ctrl usages and move to barrier_ctrl
for (DUIterator_Last imin, i = in_ctrl->last_outs(imin); i >= imin; --i) {
Node *use = in_ctrl->last_out(i);
uint l;
for (l = 0; use->in(l) != in_ctrl; l++) {}
igvn.replace_input_of(use, l, barrier_ctrl);
}
load->set_req(MemNode::Control, in_ctrl);
barrier->set_req(LoadBarrierNode::Control, in_ctrl);
zclone->add_req(barrier_val); // add req as keep alive.
C->print_method(PHASE_ADD_UNSAFE_BARRIER, 4, zclone->_idx);
}
}
void ZBarrierSetC2::insert_barriers_on_unsafe(PhaseIdealLoop* phase) const {
Compile *C = phase->C;
PhaseIterGVN &igvn = phase->igvn();
uint new_ids = C->unique();
VectorSet visited(Thread::current()->resource_area());
GrowableArray<Node *> nodeStack(Thread::current()->resource_area(), 0, 0, NULL);
nodeStack.push(C->root());
visited.test_set(C->root()->_idx);
// Traverse all nodes, visit all unsafe ops that require a barrier
while (nodeStack.length() > 0) {
Node *n = nodeStack.pop();
bool is_old_node = (n->_idx < new_ids); // don't process nodes that were created during cleanup
if (is_old_node) {
if (n->is_LoadStore()) {
LoadStoreNode* lsn = n->as_LoadStore();
if (lsn->has_barrier()) {
BasicType bt = lsn->in(MemNode::Address)->bottom_type()->basic_type();
assert ((bt == T_OBJECT || bt == T_ARRAY), "Sanity test");
insert_barrier_before_unsafe(phase, lsn);
}
}
}
for (uint i = 0; i < n->len(); i++) {
if (n->in(i)) {
if (!visited.test_set(n->in(i)->_idx)) {
nodeStack.push(n->in(i));
}
}
}
}
igvn.optimize();
C->print_method(PHASE_ADD_UNSAFE_BARRIER, 2);
}
// The purpose of ZBarrierSetC2::clean_catch_blocks is to prepare the IR for
// splicing in load barrier nodes.
//
// The problem is that we might have instructions between a call and its catch nodes.
// (This is usually handled in PhaseCFG:call_catch_cleanup, which clones mach nodes in
// already scheduled blocks.) We can't have loads that require barriers there,
// because we need to splice in new control flow, and that would violate the IR.
//
// clean_catch_blocks find all Loads that require a barrier and clone them and any
// dependent instructions to each use. The loads must be in the beginning of the catch block
// before any store.
//
// Sometimes the loads use will be at a place dominated by all catch blocks, then we need
// a load in each catch block, and a Phi at the dominated use.
void ZBarrierSetC2::clean_catch_blocks(PhaseIdealLoop* phase) const {
Compile *C = phase->C;
uint new_ids = C->unique();
PhaseIterGVN &igvn = phase->igvn();
VectorSet visited(Thread::current()->resource_area());
GrowableArray<Node *> nodeStack(Thread::current()->resource_area(), 0, 0, NULL);
nodeStack.push(C->root());
visited.test_set(C->root()->_idx);
// Traverse all nodes, visit all loads that require a barrier
while(nodeStack.length() > 0) {
Node *n = nodeStack.pop();
for (uint i = 0; i < n->len(); i++) {
if (n->in(i)) {
if (!visited.test_set(n->in(i)->_idx)) {
nodeStack.push(n->in(i));
}
}
}
bool is_old_node = (n->_idx < new_ids); // don't process nodes that were created during cleanup
if (n->is_Load() && is_old_node) {
LoadNode* load = n->isa_Load();
// only care about loads that will have a barrier
if (load_require_barrier(load)) {
process_catch_cleanup_candidate(phase, load);
}
}
}
C->print_method(PHASE_CALL_CATCH_CLEANUP, 2);
}
class DomDepthCompareClosure : public CompareClosure<LoadNode*> {
PhaseIdealLoop* _phase;
public:
DomDepthCompareClosure(PhaseIdealLoop* phase) : _phase(phase) { }
int do_compare(LoadNode* const &n1, LoadNode* const &n2) {
int d1 = _phase->dom_depth(_phase->get_ctrl(n1));
int d2 = _phase->dom_depth(_phase->get_ctrl(n2));
if (d1 == d2) {
// Compare index if the depth is the same, ensures all entries are unique.
return n1->_idx - n2->_idx;
} else {
return d2 - d1;
}
}
};
// Traverse graph and add all loadPs to list, sorted by dom depth
void gather_loadnodes_sorted(PhaseIdealLoop* phase, GrowableArray<LoadNode*>* loadList) {
VectorSet visited(Thread::current()->resource_area());
GrowableArray<Node *> nodeStack(Thread::current()->resource_area(), 0, 0, NULL);
DomDepthCompareClosure ddcc(phase);
nodeStack.push(phase->C->root());
while(nodeStack.length() > 0) {
Node *n = nodeStack.pop();
if (visited.test(n->_idx)) {
continue;
}
if (n->isa_Load()) {
LoadNode *load = n->as_Load();
if (load_require_barrier(load)) {
assert(phase->get_ctrl(load) != NULL, "sanity");
assert(phase->dom_depth(phase->get_ctrl(load)) != 0, "sanity");
loadList->insert_sorted(&ddcc, load);
}
}
visited.set(n->_idx);
for (uint i = 0; i < n->req(); i++) {
if (n->in(i)) {
if (!visited.test(n->in(i)->_idx)) {
nodeStack.push(n->in(i));
}
}
}
}
}
// Add LoadBarriers to all LoadPs
void ZBarrierSetC2::insert_load_barriers(PhaseIdealLoop* phase) const {
bool trace = phase->C->directive()->ZTraceLoadBarriersOption;
GrowableArray<LoadNode *> loadList(Thread::current()->resource_area(), 0, 0, NULL);
gather_loadnodes_sorted(phase, &loadList);
PhaseIterGVN &igvn = phase->igvn();
int count = 0;
for (GrowableArrayIterator<LoadNode *> loadIter = loadList.begin(); loadIter != loadList.end(); ++loadIter) {
LoadNode *load = *loadIter;
if (load_has_expanded_barrier(load)) {
continue;
}
do {
// Insert a barrier on a loadP
// if another load is found that needs to be expanded first, retry on that one
LoadNode* result = insert_one_loadbarrier(phase, load, phase->get_ctrl(load));
while (result != NULL) {
result = insert_one_loadbarrier(phase, result, phase->get_ctrl(result));
}
} while (!load_has_expanded_barrier(load));
}
phase->C->print_method(PHASE_INSERT_BARRIER, 2);
}
void push_antidependent_stores(PhaseIdealLoop* phase, Node_Stack& nodestack, LoadNode* start_load) {
// push all stores on the same mem, that can_alias
// Any load found must be handled first
PhaseIterGVN &igvn = phase->igvn();
int load_alias_idx = igvn.C->get_alias_index(start_load->adr_type());
Node *mem = start_load->in(1);
for (DUIterator_Fast imax, u = mem->fast_outs(imax); u < imax; u++) {
Node *mem_use = mem->fast_out(u);
if (mem_use == start_load) continue;
if (!mem_use->is_Store()) continue;
if (!phase->has_ctrl(mem_use)) continue;
if (phase->get_ctrl(mem_use) != phase->get_ctrl(start_load)) continue;
// add any aliasing store in this block
StoreNode *store = mem_use->isa_Store();
const TypePtr *adr_type = store->adr_type();
if (igvn.C->can_alias(adr_type, load_alias_idx)) {
nodestack.push(store, 0);
}
}
}
LoadNode* ZBarrierSetC2::insert_one_loadbarrier(PhaseIdealLoop* phase, LoadNode* start_load, Node* ctrl) const {
bool trace = phase->C->directive()->ZTraceLoadBarriersOption;
PhaseIterGVN &igvn = phase->igvn();
// Check for other loadPs at the same loop depth that is reachable by a DFS
// - if found - return it. It needs to be inserted first
// - otherwise proceed and insert barrier
VectorSet visited(Thread::current()->resource_area());
Node_Stack nodestack(100);
nodestack.push(start_load, 0);
push_antidependent_stores(phase, nodestack, start_load);
while(!nodestack.is_empty()) {
Node* n = nodestack.node(); // peek
nodestack.pop();
if (visited.test(n->_idx)) {
continue;
}
if (n->is_Load() && n != start_load && load_require_barrier(n->as_Load()) && !load_has_expanded_barrier(n->as_Load())) {
// Found another load that needs a barrier in the same block. Must expand later loads first.
if (trace) tty->print_cr(" * Found LoadP %i on DFS", n->_idx);
return n->as_Load(); // return node that should be expanded first
}
if (!phase->has_ctrl(n)) continue;
if (phase->get_ctrl(n) != phase->get_ctrl(start_load)) continue;
if (n->is_Phi()) continue;
visited.set(n->_idx);
// push all children
for (DUIterator_Fast imax, ii = n->fast_outs(imax); ii < imax; ii++) {
Node* c = n->fast_out(ii);
if (c != NULL) {
nodestack.push(c, 0);
}
}
}
insert_one_loadbarrier_inner(phase, start_load, ctrl, visited);
return NULL;
}
void ZBarrierSetC2::insert_one_loadbarrier_inner(PhaseIdealLoop* phase, LoadNode* load, Node* ctrl, VectorSet visited2) const {
PhaseIterGVN &igvn = phase->igvn();
Compile* C = igvn.C;
bool trace = C->directive()->ZTraceLoadBarriersOption;
// create barrier
Node* barrier = new LoadBarrierNode(C, NULL, load->in(LoadNode::Memory), NULL, load->in(LoadNode::Address), load_has_weak_barrier(load));
Node* barrier_val = new ProjNode(barrier, LoadBarrierNode::Oop);
Node* barrier_ctrl = new ProjNode(barrier, LoadBarrierNode::Control);
if (trace) tty->print_cr("Insert load %i with barrier: %i and ctrl : %i", load->_idx, barrier->_idx, ctrl->_idx);
// Splice control
// - insert barrier control diamond between loads ctrl and ctrl successor on path to block end.
// - If control successor is a catch, step over to next.
Node* ctrl_succ = NULL;
for (DUIterator_Fast imax, j = ctrl->fast_outs(imax); j < imax; j++) {
Node* tmp = ctrl->fast_out(j);
// - CFG nodes is the ones we are going to splice (1 only!)
// - Phi nodes will continue to hang from the region node!
// - self loops should be skipped
if (tmp->is_Phi() || tmp == ctrl) {
continue;
}
if (tmp->is_CFG()) {
assert(ctrl_succ == NULL, "There can be only one");
ctrl_succ = tmp;
continue;
}
}
// Now splice control
assert(ctrl_succ != load, "sanity");
assert(ctrl_succ != NULL, "Broken IR");
bool found = false;
for(uint k = 0; k < ctrl_succ->req(); k++) {
if (ctrl_succ->in(k) == ctrl) {
assert(!found, "sanity");
if (trace) tty->print_cr(" Move CFG ctrl_succ %i to barrier_ctrl", ctrl_succ->_idx);
igvn.replace_input_of(ctrl_succ, k, barrier_ctrl);
found = true;
k--;
}
}
// For all successors of ctrl - move all visited to become successors of barrier_ctrl instead
for (DUIterator_Fast imax, r = ctrl->fast_outs(imax); r < imax; r++) {
Node* tmp = ctrl->fast_out(r);
if (visited2.test(tmp->_idx) && (tmp != load)) {
if (trace) tty->print_cr(" Move ctrl_succ %i to barrier_ctrl", tmp->_idx);
igvn.replace_input_of(tmp, 0, barrier_ctrl);
--r; --imax;
}
}
// Move the loads user to the barrier
for (DUIterator_Fast imax, i = load->fast_outs(imax); i < imax; i++) {
Node* u = load->fast_out(i);
if (u->isa_LoadBarrier()) {
continue;
}
// find correct input - replace with iterator?
for(uint j = 0; j < u->req(); j++) {
if (u->in(j) == load) {
igvn.replace_input_of(u, j, barrier_val);
--i; --imax; // Adjust the iterator of the *outer* loop
break; // some nodes (calls) might have several uses from the same node
}
}
}
// Connect barrier to load and control
barrier->set_req(LoadBarrierNode::Oop, load);
barrier->set_req(LoadBarrierNode::Control, ctrl);
igvn.rehash_node_delayed(load);
igvn.register_new_node_with_optimizer(barrier);
igvn.register_new_node_with_optimizer(barrier_val);
igvn.register_new_node_with_optimizer(barrier_ctrl);
load_set_expanded_barrier(load);
C->print_method(PHASE_INSERT_BARRIER, 3, load->_idx);
}
// The bad_mask in the ThreadLocalData shouldn't have an anti-dep-check.
// The bad_mask address if of type TypeRawPtr, but that will alias
// InitializeNodes until the type system is expanded.
bool ZBarrierSetC2::needs_anti_dependence_check(const Node* node) const {
MachNode* mnode = node->as_Mach();
if (mnode != NULL) {
intptr_t offset = 0;
const TypePtr *adr_type2 = NULL;
const Node* base = mnode->get_base_and_disp(offset, adr_type2);
if ((base != NULL) &&
(base->is_Mach() && base->as_Mach()->ideal_Opcode() == Op_ThreadLocal) &&
(offset == in_bytes(ZThreadLocalData::address_bad_mask_offset()))) {
return false;
}
}
return true;
}