/*
* Copyright (c) 2005, 2014, 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 "c1/c1_Instruction.hpp"
#include "c1/c1_LinearScan.hpp"
#include "utilities/bitMap.inline.hpp"
//----------------------------------------------------------------------
// Allocation of FPU stack slots (Intel x86 only)
//----------------------------------------------------------------------
void LinearScan::allocate_fpu_stack() {
// First compute which FPU registers are live at the start of each basic block
// (To minimize the amount of work we have to do if we have to merge FPU stacks)
if (ComputeExactFPURegisterUsage) {
Interval* intervals_in_register, *intervals_in_memory;
create_unhandled_lists(&intervals_in_register, &intervals_in_memory, is_in_fpu_register, NULL);
// ignore memory intervals by overwriting intervals_in_memory
// the dummy interval is needed to enforce the walker to walk until the given id:
// without it, the walker stops when the unhandled-list is empty -> live information
// beyond this point would be incorrect.
Interval* dummy_interval = new Interval(any_reg);
dummy_interval->add_range(max_jint - 2, max_jint - 1);
dummy_interval->set_next(Interval::end());
intervals_in_memory = dummy_interval;
IntervalWalker iw(this, intervals_in_register, intervals_in_memory);
const int num_blocks = block_count();
for (int i = 0; i < num_blocks; i++) {
BlockBegin* b = block_at(i);
// register usage is only needed for merging stacks -> compute only
// when more than one predecessor.
// the block must not have any spill moves at the beginning (checked by assertions)
// spill moves would use intervals that are marked as handled and so the usage bit
// would been set incorrectly
// NOTE: the check for number_of_preds > 1 is necessary. A block with only one
// predecessor may have spill moves at the begin of the block.
// If an interval ends at the current instruction id, it is not possible
// to decide if the register is live or not at the block begin -> the
// register information would be incorrect.
if (b->number_of_preds() > 1) {
int id = b->first_lir_instruction_id();
ResourceBitMap regs(FrameMap::nof_fpu_regs);
regs.clear();
iw.walk_to(id); // walk after the first instruction (always a label) of the block
assert(iw.current_position() == id, "did not walk completely to id");
// Only consider FPU values in registers
Interval* interval = iw.active_first(fixedKind);
while (interval != Interval::end()) {
int reg = interval->assigned_reg();
assert(reg >= pd_first_fpu_reg && reg <= pd_last_fpu_reg, "no fpu register");
assert(interval->assigned_regHi() == -1, "must not have hi register (doubles stored in one register)");
assert(interval->from() <= id && id < interval->to(), "interval out of range");
#ifndef PRODUCT
if (TraceFPURegisterUsage) {
tty->print("fpu reg %d is live because of ", reg - pd_first_fpu_reg); interval->print();
}
#endif
regs.set_bit(reg - pd_first_fpu_reg);
interval = interval->next();
}
b->set_fpu_register_usage(regs);
#ifndef PRODUCT
if (TraceFPURegisterUsage) {
tty->print("FPU regs for block %d, LIR instr %d): ", b->block_id(), id); regs.print_on(tty); tty->cr();
}
#endif
}
}
}
FpuStackAllocator alloc(ir()->compilation(), this);
_fpu_stack_allocator = &alloc;
alloc.allocate();
_fpu_stack_allocator = NULL;
}
FpuStackAllocator::FpuStackAllocator(Compilation* compilation, LinearScan* allocator)
: _compilation(compilation)
, _lir(NULL)
, _pos(-1)
, _allocator(allocator)
, _sim(compilation)
, _temp_sim(compilation)
{}
void FpuStackAllocator::allocate() {
int num_blocks = allocator()->block_count();
for (int i = 0; i < num_blocks; i++) {
// Set up to process block
BlockBegin* block = allocator()->block_at(i);
intArray* fpu_stack_state = block->fpu_stack_state();
#ifndef PRODUCT
if (TraceFPUStack) {
tty->cr();
tty->print_cr("------- Begin of new Block %d -------", block->block_id());
}
#endif
assert(fpu_stack_state != NULL ||
block->end()->as_Base() != NULL ||
block->is_set(BlockBegin::exception_entry_flag),
"FPU stack state must be present due to linear-scan order for FPU stack allocation");
// note: exception handler entries always start with an empty fpu stack
// because stack merging would be too complicated
if (fpu_stack_state != NULL) {
sim()->read_state(fpu_stack_state);
} else {
sim()->clear();
}
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print("Reading FPU state for block %d:", block->block_id());
sim()->print();
tty->cr();
}
#endif
allocate_block(block);
CHECK_BAILOUT();
}
}
void FpuStackAllocator::allocate_block(BlockBegin* block) {
bool processed_merge = false;
LIR_OpList* insts = block->lir()->instructions_list();
set_lir(block->lir());
set_pos(0);
// Note: insts->length() may change during loop
while (pos() < insts->length()) {
LIR_Op* op = insts->at(pos());
_debug_information_computed = false;
#ifndef PRODUCT
if (TraceFPUStack) {
op->print();
}
check_invalid_lir_op(op);
#endif
LIR_OpBranch* branch = op->as_OpBranch();
LIR_Op1* op1 = op->as_Op1();
LIR_Op2* op2 = op->as_Op2();
LIR_OpCall* opCall = op->as_OpCall();
if (branch != NULL && branch->block() != NULL) {
if (!processed_merge) {
// propagate stack at first branch to a successor
processed_merge = true;
bool required_merge = merge_fpu_stack_with_successors(block);
assert(!required_merge || branch->cond() == lir_cond_always, "splitting of critical edges should prevent FPU stack mismatches at cond branches");
}
} else if (op1 != NULL) {
handle_op1(op1);
} else if (op2 != NULL) {
handle_op2(op2);
} else if (opCall != NULL) {
handle_opCall(opCall);
}
compute_debug_information(op);
set_pos(1 + pos());
}
// Propagate stack when block does not end with branch
if (!processed_merge) {
merge_fpu_stack_with_successors(block);
}
}
void FpuStackAllocator::compute_debug_information(LIR_Op* op) {
if (!_debug_information_computed && op->id() != -1 && allocator()->has_info(op->id())) {
visitor.visit(op);
// exception handling
if (allocator()->compilation()->has_exception_handlers()) {
XHandlers* xhandlers = visitor.all_xhandler();
int n = xhandlers->length();
for (int k = 0; k < n; k++) {
allocate_exception_handler(xhandlers->handler_at(k));
}
} else {
assert(visitor.all_xhandler()->length() == 0, "missed exception handler");
}
// compute debug information
int n = visitor.info_count();
assert(n > 0, "should not visit operation otherwise");
for (int j = 0; j < n; j++) {
CodeEmitInfo* info = visitor.info_at(j);
// Compute debug information
allocator()->compute_debug_info(info, op->id());
}
}
_debug_information_computed = true;
}
void FpuStackAllocator::allocate_exception_handler(XHandler* xhandler) {
if (!sim()->is_empty()) {
LIR_List* old_lir = lir();
int old_pos = pos();
intArray* old_state = sim()->write_state();
#ifndef PRODUCT
if (TraceFPUStack) {
tty->cr();
tty->print_cr("------- begin of exception handler -------");
}
#endif
if (xhandler->entry_code() == NULL) {
// need entry code to clear FPU stack
LIR_List* entry_code = new LIR_List(_compilation);
entry_code->jump(xhandler->entry_block());
xhandler->set_entry_code(entry_code);
}
LIR_OpList* insts = xhandler->entry_code()->instructions_list();
set_lir(xhandler->entry_code());
set_pos(0);
// Note: insts->length() may change during loop
while (pos() < insts->length()) {
LIR_Op* op = insts->at(pos());
#ifndef PRODUCT
if (TraceFPUStack) {
op->print();
}
check_invalid_lir_op(op);
#endif
switch (op->code()) {
case lir_move:
assert(op->as_Op1() != NULL, "must be LIR_Op1");
assert(pos() != insts->length() - 1, "must not be last operation");
handle_op1((LIR_Op1*)op);
break;
case lir_branch:
assert(op->as_OpBranch()->cond() == lir_cond_always, "must be unconditional branch");
assert(pos() == insts->length() - 1, "must be last operation");
// remove all remaining dead registers from FPU stack
clear_fpu_stack(LIR_OprFact::illegalOpr);
break;
default:
// other operations not allowed in exception entry code
ShouldNotReachHere();
}
set_pos(pos() + 1);
}
#ifndef PRODUCT
if (TraceFPUStack) {
tty->cr();
tty->print_cr("------- end of exception handler -------");
}
#endif
set_lir(old_lir);
set_pos(old_pos);
sim()->read_state(old_state);
}
}
int FpuStackAllocator::fpu_num(LIR_Opr opr) {
assert(opr->is_fpu_register() && !opr->is_xmm_register(), "shouldn't call this otherwise");
return opr->is_single_fpu() ? opr->fpu_regnr() : opr->fpu_regnrLo();
}
int FpuStackAllocator::tos_offset(LIR_Opr opr) {
return sim()->offset_from_tos(fpu_num(opr));
}
LIR_Opr FpuStackAllocator::to_fpu_stack(LIR_Opr opr) {
assert(opr->is_fpu_register() && !opr->is_xmm_register(), "shouldn't call this otherwise");
int stack_offset = tos_offset(opr);
if (opr->is_single_fpu()) {
return LIR_OprFact::single_fpu(stack_offset)->make_fpu_stack_offset();
} else {
assert(opr->is_double_fpu(), "shouldn't call this otherwise");
return LIR_OprFact::double_fpu(stack_offset)->make_fpu_stack_offset();
}
}
LIR_Opr FpuStackAllocator::to_fpu_stack_top(LIR_Opr opr, bool dont_check_offset) {
assert(opr->is_fpu_register() && !opr->is_xmm_register(), "shouldn't call this otherwise");
assert(dont_check_offset || tos_offset(opr) == 0, "operand is not on stack top");
int stack_offset = 0;
if (opr->is_single_fpu()) {
return LIR_OprFact::single_fpu(stack_offset)->make_fpu_stack_offset();
} else {
assert(opr->is_double_fpu(), "shouldn't call this otherwise");
return LIR_OprFact::double_fpu(stack_offset)->make_fpu_stack_offset();
}
}
void FpuStackAllocator::insert_op(LIR_Op* op) {
lir()->insert_before(pos(), op);
set_pos(1 + pos());
}
void FpuStackAllocator::insert_exchange(int offset) {
if (offset > 0) {
LIR_Op1* fxch_op = new LIR_Op1(lir_fxch, LIR_OprFact::intConst(offset), LIR_OprFact::illegalOpr);
insert_op(fxch_op);
sim()->swap(offset);
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print("Exchanged register: %d New state: ", sim()->get_slot(0)); sim()->print(); tty->cr();
}
#endif
}
}
void FpuStackAllocator::insert_exchange(LIR_Opr opr) {
insert_exchange(tos_offset(opr));
}
void FpuStackAllocator::insert_free(int offset) {
// move stack slot to the top of stack and then pop it
insert_exchange(offset);
LIR_Op* fpop = new LIR_Op0(lir_fpop_raw);
insert_op(fpop);
sim()->pop();
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print("Inserted pop New state: "); sim()->print(); tty->cr();
}
#endif
}
void FpuStackAllocator::insert_free_if_dead(LIR_Opr opr) {
if (sim()->contains(fpu_num(opr))) {
int res_slot = tos_offset(opr);
insert_free(res_slot);
}
}
void FpuStackAllocator::insert_free_if_dead(LIR_Opr opr, LIR_Opr ignore) {
if (fpu_num(opr) != fpu_num(ignore) && sim()->contains(fpu_num(opr))) {
int res_slot = tos_offset(opr);
insert_free(res_slot);
}
}
void FpuStackAllocator::insert_copy(LIR_Opr from, LIR_Opr to) {
int offset = tos_offset(from);
LIR_Op1* fld = new LIR_Op1(lir_fld, LIR_OprFact::intConst(offset), LIR_OprFact::illegalOpr);
insert_op(fld);
sim()->push(fpu_num(to));
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print("Inserted copy (%d -> %d) New state: ", fpu_num(from), fpu_num(to)); sim()->print(); tty->cr();
}
#endif
}
void FpuStackAllocator::do_rename(LIR_Opr from, LIR_Opr to) {
sim()->rename(fpu_num(from), fpu_num(to));
}
void FpuStackAllocator::do_push(LIR_Opr opr) {
sim()->push(fpu_num(opr));
}
void FpuStackAllocator::pop_if_last_use(LIR_Op* op, LIR_Opr opr) {
assert(op->fpu_pop_count() == 0, "fpu_pop_count alredy set");
assert(tos_offset(opr) == 0, "can only pop stack top");
if (opr->is_last_use()) {
op->set_fpu_pop_count(1);
sim()->pop();
}
}
void FpuStackAllocator::pop_always(LIR_Op* op, LIR_Opr opr) {
assert(op->fpu_pop_count() == 0, "fpu_pop_count alredy set");
assert(tos_offset(opr) == 0, "can only pop stack top");
op->set_fpu_pop_count(1);
sim()->pop();
}
void FpuStackAllocator::clear_fpu_stack(LIR_Opr preserve) {
int result_stack_size = (preserve->is_fpu_register() && !preserve->is_xmm_register() ? 1 : 0);
while (sim()->stack_size() > result_stack_size) {
assert(!sim()->slot_is_empty(0), "not allowed");
if (result_stack_size == 0 || sim()->get_slot(0) != fpu_num(preserve)) {
insert_free(0);
} else {
// move "preserve" to bottom of stack so that all other stack slots can be popped
insert_exchange(sim()->stack_size() - 1);
}
}
}
void FpuStackAllocator::handle_op1(LIR_Op1* op1) {
LIR_Opr in = op1->in_opr();
LIR_Opr res = op1->result_opr();
LIR_Opr new_in = in; // new operands relative to the actual fpu stack top
LIR_Opr new_res = res;
// Note: this switch is processed for all LIR_Op1, regardless if they have FPU-arguments,
// so checks for is_float_kind() are necessary inside the cases
switch (op1->code()) {
case lir_return: {
// FPU-Stack must only contain the (optional) fpu return value.
// All remaining dead values are popped from the stack
// If the input operand is a fpu-register, it is exchanged to the bottom of the stack
clear_fpu_stack(in);
if (in->is_fpu_register() && !in->is_xmm_register()) {
new_in = to_fpu_stack_top(in);
}
break;
}
case lir_move: {
if (in->is_fpu_register() && !in->is_xmm_register()) {
if (res->is_xmm_register()) {
// move from fpu register to xmm register (necessary for operations that
// are not available in the SSE instruction set)
insert_exchange(in);
new_in = to_fpu_stack_top(in);
pop_always(op1, in);
} else if (res->is_fpu_register() && !res->is_xmm_register()) {
// move from fpu-register to fpu-register:
// * input and result register equal:
// nothing to do
// * input register is last use:
// rename the input register to result register -> input register
// not present on fpu-stack afterwards
// * input register not last use:
// duplicate input register to result register to preserve input
//
// Note: The LIR-Assembler does not produce any code for fpu register moves,
// so input and result stack index must be equal
if (fpu_num(in) == fpu_num(res)) {
// nothing to do
} else if (in->is_last_use()) {
insert_free_if_dead(res);//, in);
do_rename(in, res);
} else {
insert_free_if_dead(res);
insert_copy(in, res);
}
new_in = to_fpu_stack(res);
new_res = new_in;
} else {
// move from fpu-register to memory
// input operand must be on top of stack
insert_exchange(in);
// create debug information here because afterwards the register may have been popped
compute_debug_information(op1);
new_in = to_fpu_stack_top(in);
pop_if_last_use(op1, in);
}
} else if (res->is_fpu_register() && !res->is_xmm_register()) {
// move from memory/constant to fpu register
// result is pushed on the stack
insert_free_if_dead(res);
// create debug information before register is pushed
compute_debug_information(op1);
do_push(res);
new_res = to_fpu_stack_top(res);
}
break;
}
case lir_neg: {
if (in->is_fpu_register() && !in->is_xmm_register()) {
assert(res->is_fpu_register() && !res->is_xmm_register(), "must be");
assert(in->is_last_use(), "old value gets destroyed");
insert_free_if_dead(res, in);
insert_exchange(in);
new_in = to_fpu_stack_top(in);
do_rename(in, res);
new_res = to_fpu_stack_top(res);
}
break;
}
case lir_convert: {
Bytecodes::Code bc = op1->as_OpConvert()->bytecode();
switch (bc) {
case Bytecodes::_d2f:
case Bytecodes::_f2d:
assert(res->is_fpu_register(), "must be");
assert(in->is_fpu_register(), "must be");
if (!in->is_xmm_register() && !res->is_xmm_register()) {
// this is quite the same as a move from fpu-register to fpu-register
// Note: input and result operands must have different types
if (fpu_num(in) == fpu_num(res)) {
// nothing to do
new_in = to_fpu_stack(in);
} else if (in->is_last_use()) {
insert_free_if_dead(res);//, in);
new_in = to_fpu_stack(in);
do_rename(in, res);
} else {
insert_free_if_dead(res);
insert_copy(in, res);
new_in = to_fpu_stack_top(in, true);
}
new_res = to_fpu_stack(res);
}
break;
case Bytecodes::_i2f:
case Bytecodes::_l2f:
case Bytecodes::_i2d:
case Bytecodes::_l2d:
assert(res->is_fpu_register(), "must be");
if (!res->is_xmm_register()) {
insert_free_if_dead(res);
do_push(res);
new_res = to_fpu_stack_top(res);
}
break;
case Bytecodes::_f2i:
case Bytecodes::_d2i:
assert(in->is_fpu_register(), "must be");
if (!in->is_xmm_register()) {
insert_exchange(in);
new_in = to_fpu_stack_top(in);
// TODO: update registes of stub
}
break;
case Bytecodes::_f2l:
case Bytecodes::_d2l:
assert(in->is_fpu_register(), "must be");
if (!in->is_xmm_register()) {
insert_exchange(in);
new_in = to_fpu_stack_top(in);
pop_always(op1, in);
}
break;
case Bytecodes::_i2l:
case Bytecodes::_l2i:
case Bytecodes::_i2b:
case Bytecodes::_i2c:
case Bytecodes::_i2s:
// no fpu operands
break;
default:
ShouldNotReachHere();
}
break;
}
case lir_roundfp: {
assert(in->is_fpu_register() && !in->is_xmm_register(), "input must be in register");
assert(res->is_stack(), "result must be on stack");
insert_exchange(in);
new_in = to_fpu_stack_top(in);
pop_if_last_use(op1, in);
break;
}
default: {
assert(!in->is_float_kind() && !res->is_float_kind(), "missed a fpu-operation");
}
}
op1->set_in_opr(new_in);
op1->set_result_opr(new_res);
}
void FpuStackAllocator::handle_op2(LIR_Op2* op2) {
LIR_Opr left = op2->in_opr1();
if (!left->is_float_kind()) {
return;
}
if (left->is_xmm_register()) {
return;
}
LIR_Opr right = op2->in_opr2();
LIR_Opr res = op2->result_opr();
LIR_Opr new_left = left; // new operands relative to the actual fpu stack top
LIR_Opr new_right = right;
LIR_Opr new_res = res;
assert(!left->is_xmm_register() && !right->is_xmm_register() && !res->is_xmm_register(), "not for xmm registers");
switch (op2->code()) {
case lir_cmp:
case lir_cmp_fd2i:
case lir_ucmp_fd2i:
case lir_assert: {
assert(left->is_fpu_register(), "invalid LIR");
assert(right->is_fpu_register(), "invalid LIR");
// the left-hand side must be on top of stack.
// the right-hand side is never popped, even if is_last_use is set
insert_exchange(left);
new_left = to_fpu_stack_top(left);
new_right = to_fpu_stack(right);
pop_if_last_use(op2, left);
break;
}
case lir_mul_strictfp:
case lir_div_strictfp: {
assert(op2->tmp1_opr()->is_fpu_register(), "strict operations need temporary fpu stack slot");
insert_free_if_dead(op2->tmp1_opr());
assert(sim()->stack_size() <= 7, "at least one stack slot must be free");
// fall-through: continue with the normal handling of lir_mul and lir_div
}
case lir_add:
case lir_sub:
case lir_mul:
case lir_div: {
assert(left->is_fpu_register(), "must be");
assert(res->is_fpu_register(), "must be");
assert(left->is_equal(res), "must be");
// either the left-hand or the right-hand side must be on top of stack
// (if right is not a register, left must be on top)
if (!right->is_fpu_register()) {
insert_exchange(left);
new_left = to_fpu_stack_top(left);
} else {
// no exchange necessary if right is alredy on top of stack
if (tos_offset(right) == 0) {
new_left = to_fpu_stack(left);
new_right = to_fpu_stack_top(right);
} else {
insert_exchange(left);
new_left = to_fpu_stack_top(left);
new_right = to_fpu_stack(right);
}
if (right->is_last_use()) {
op2->set_fpu_pop_count(1);
if (tos_offset(right) == 0) {
sim()->pop();
} else {
// if left is on top of stack, the result is placed in the stack
// slot of right, so a renaming from right to res is necessary
assert(tos_offset(left) == 0, "must be");
sim()->pop();
do_rename(right, res);
}
}
}
new_res = to_fpu_stack(res);
break;
}
case lir_rem: {
assert(left->is_fpu_register(), "must be");
assert(right->is_fpu_register(), "must be");
assert(res->is_fpu_register(), "must be");
assert(left->is_equal(res), "must be");
// Must bring both operands to top of stack with following operand ordering:
// * fpu stack before rem: ... right left
// * fpu stack after rem: ... left
if (tos_offset(right) != 1) {
insert_exchange(right);
insert_exchange(1);
}
insert_exchange(left);
assert(tos_offset(right) == 1, "check");
assert(tos_offset(left) == 0, "check");
new_left = to_fpu_stack_top(left);
new_right = to_fpu_stack(right);
op2->set_fpu_pop_count(1);
sim()->pop();
do_rename(right, res);
new_res = to_fpu_stack_top(res);
break;
}
case lir_abs:
case lir_sqrt: {
// Right argument appears to be unused
assert(right->is_illegal(), "must be");
assert(left->is_fpu_register(), "must be");
assert(res->is_fpu_register(), "must be");
assert(left->is_last_use(), "old value gets destroyed");
insert_free_if_dead(res, left);
insert_exchange(left);
do_rename(left, res);
new_left = to_fpu_stack_top(res);
new_res = new_left;
op2->set_fpu_stack_size(sim()->stack_size());
break;
}
default: {
assert(false, "missed a fpu-operation");
}
}
op2->set_in_opr1(new_left);
op2->set_in_opr2(new_right);
op2->set_result_opr(new_res);
}
void FpuStackAllocator::handle_opCall(LIR_OpCall* opCall) {
LIR_Opr res = opCall->result_opr();
// clear fpu-stack before call
// it may contain dead values that could not have been remved by previous operations
clear_fpu_stack(LIR_OprFact::illegalOpr);
assert(sim()->is_empty(), "fpu stack must be empty now");
// compute debug information before (possible) fpu result is pushed
compute_debug_information(opCall);
if (res->is_fpu_register() && !res->is_xmm_register()) {
do_push(res);
opCall->set_result_opr(to_fpu_stack_top(res));
}
}
#ifndef PRODUCT
void FpuStackAllocator::check_invalid_lir_op(LIR_Op* op) {
switch (op->code()) {
case lir_24bit_FPU:
case lir_reset_FPU:
case lir_ffree:
assert(false, "operations not allowed in lir. If one of these operations is needed, check if they have fpu operands");
break;
case lir_fpop_raw:
case lir_fxch:
case lir_fld:
assert(false, "operations only inserted by FpuStackAllocator");
break;
}
}
#endif
void FpuStackAllocator::merge_insert_add(LIR_List* instrs, FpuStackSim* cur_sim, int reg) {
LIR_Op1* move = new LIR_Op1(lir_move, LIR_OprFact::doubleConst(0), LIR_OprFact::double_fpu(reg)->make_fpu_stack_offset());
instrs->instructions_list()->push(move);
cur_sim->push(reg);
move->set_result_opr(to_fpu_stack(move->result_opr()));
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print("Added new register: %d New state: ", reg); cur_sim->print(); tty->cr();
}
#endif
}
void FpuStackAllocator::merge_insert_xchg(LIR_List* instrs, FpuStackSim* cur_sim, int slot) {
assert(slot > 0, "no exchange necessary");
LIR_Op1* fxch = new LIR_Op1(lir_fxch, LIR_OprFact::intConst(slot));
instrs->instructions_list()->push(fxch);
cur_sim->swap(slot);
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print("Exchanged register: %d New state: ", cur_sim->get_slot(slot)); cur_sim->print(); tty->cr();
}
#endif
}
void FpuStackAllocator::merge_insert_pop(LIR_List* instrs, FpuStackSim* cur_sim) {
int reg = cur_sim->get_slot(0);
LIR_Op* fpop = new LIR_Op0(lir_fpop_raw);
instrs->instructions_list()->push(fpop);
cur_sim->pop(reg);
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print("Removed register: %d New state: ", reg); cur_sim->print(); tty->cr();
}
#endif
}
bool FpuStackAllocator::merge_rename(FpuStackSim* cur_sim, FpuStackSim* sux_sim, int start_slot, int change_slot) {
int reg = cur_sim->get_slot(change_slot);
for (int slot = start_slot; slot >= 0; slot--) {
int new_reg = sux_sim->get_slot(slot);
if (!cur_sim->contains(new_reg)) {
cur_sim->set_slot(change_slot, new_reg);
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print("Renamed register %d to %d New state: ", reg, new_reg); cur_sim->print(); tty->cr();
}
#endif
return true;
}
}
return false;
}
void FpuStackAllocator::merge_fpu_stack(LIR_List* instrs, FpuStackSim* cur_sim, FpuStackSim* sux_sim) {
#ifndef PRODUCT
if (TraceFPUStack) {
tty->cr();
tty->print("before merging: pred: "); cur_sim->print(); tty->cr();
tty->print(" sux: "); sux_sim->print(); tty->cr();
}
int slot;
for (slot = 0; slot < cur_sim->stack_size(); slot++) {
assert(!cur_sim->slot_is_empty(slot), "not handled by algorithm");
}
for (slot = 0; slot < sux_sim->stack_size(); slot++) {
assert(!sux_sim->slot_is_empty(slot), "not handled by algorithm");
}
#endif
// size difference between cur and sux that must be resolved by adding or removing values form the stack
int size_diff = cur_sim->stack_size() - sux_sim->stack_size();
if (!ComputeExactFPURegisterUsage) {
// add slots that are currently free, but used in successor
// When the exact FPU register usage is computed, the stack does
// not contain dead values at merging -> no values must be added
int sux_slot = sux_sim->stack_size() - 1;
while (size_diff < 0) {
assert(sux_slot >= 0, "slot out of bounds -> error in algorithm");
int reg = sux_sim->get_slot(sux_slot);
if (!cur_sim->contains(reg)) {
merge_insert_add(instrs, cur_sim, reg);
size_diff++;
if (sux_slot + size_diff != 0) {
merge_insert_xchg(instrs, cur_sim, sux_slot + size_diff);
}
}
sux_slot--;
}
}
assert(cur_sim->stack_size() >= sux_sim->stack_size(), "stack size must be equal or greater now");
assert(size_diff == cur_sim->stack_size() - sux_sim->stack_size(), "must be");
// stack merge algorithm:
// 1) as long as the current stack top is not in the right location (that meens
// it should not be on the stack top), exchange it into the right location
// 2) if the stack top is right, but the remaining stack is not ordered correctly,
// the stack top is exchanged away to get another value on top ->
// now step 1) can be continued
// the stack can also contain unused items -> these items are removed from stack
int finished_slot = sux_sim->stack_size() - 1;
while (finished_slot >= 0 || size_diff > 0) {
while (size_diff > 0 || (cur_sim->stack_size() > 0 && cur_sim->get_slot(0) != sux_sim->get_slot(0))) {
int reg = cur_sim->get_slot(0);
if (sux_sim->contains(reg)) {
int sux_slot = sux_sim->offset_from_tos(reg);
merge_insert_xchg(instrs, cur_sim, sux_slot + size_diff);
} else if (!merge_rename(cur_sim, sux_sim, finished_slot, 0)) {
assert(size_diff > 0, "must be");
merge_insert_pop(instrs, cur_sim);
size_diff--;
}
assert(cur_sim->stack_size() == 0 || cur_sim->get_slot(0) != reg, "register must have been changed");
}
while (finished_slot >= 0 && cur_sim->get_slot(finished_slot) == sux_sim->get_slot(finished_slot)) {
finished_slot--;
}
if (finished_slot >= 0) {
int reg = cur_sim->get_slot(finished_slot);
if (sux_sim->contains(reg) || !merge_rename(cur_sim, sux_sim, finished_slot, finished_slot)) {
assert(sux_sim->contains(reg) || size_diff > 0, "must be");
merge_insert_xchg(instrs, cur_sim, finished_slot);
}
assert(cur_sim->get_slot(finished_slot) != reg, "register must have been changed");
}
}
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print("after merging: pred: "); cur_sim->print(); tty->cr();
tty->print(" sux: "); sux_sim->print(); tty->cr();
tty->cr();
}
#endif
assert(cur_sim->stack_size() == sux_sim->stack_size(), "stack size must be equal now");
}
void FpuStackAllocator::merge_cleanup_fpu_stack(LIR_List* instrs, FpuStackSim* cur_sim, BitMap& live_fpu_regs) {
#ifndef PRODUCT
if (TraceFPUStack) {
tty->cr();
tty->print("before cleanup: state: "); cur_sim->print(); tty->cr();
tty->print(" live: "); live_fpu_regs.print_on(tty); tty->cr();
}
#endif
int slot = 0;
while (slot < cur_sim->stack_size()) {
int reg = cur_sim->get_slot(slot);
if (!live_fpu_regs.at(reg)) {
if (slot != 0) {
merge_insert_xchg(instrs, cur_sim, slot);
}
merge_insert_pop(instrs, cur_sim);
} else {
slot++;
}
}
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print("after cleanup: state: "); cur_sim->print(); tty->cr();
tty->print(" live: "); live_fpu_regs.print_on(tty); tty->cr();
tty->cr();
}
// check if fpu stack only contains live registers
for (unsigned int i = 0; i < live_fpu_regs.size(); i++) {
if (live_fpu_regs.at(i) != cur_sim->contains(i)) {
tty->print_cr("mismatch between required and actual stack content");
break;
}
}
#endif
}
bool FpuStackAllocator::merge_fpu_stack_with_successors(BlockBegin* block) {
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print_cr("Propagating FPU stack state for B%d at LIR_Op position %d to successors:",
block->block_id(), pos());
sim()->print();
tty->cr();
}
#endif
bool changed = false;
int number_of_sux = block->number_of_sux();
if (number_of_sux == 1 && block->sux_at(0)->number_of_preds() > 1) {
// The successor has at least two incoming edges, so a stack merge will be necessary
// If this block is the first predecessor, cleanup the current stack and propagate it
// If this block is not the first predecessor, a stack merge will be necessary
BlockBegin* sux = block->sux_at(0);
intArray* state = sux->fpu_stack_state();
LIR_List* instrs = new LIR_List(_compilation);
if (state != NULL) {
// Merge with a successors that already has a FPU stack state
// the block must only have one successor because critical edges must been split
FpuStackSim* cur_sim = sim();
FpuStackSim* sux_sim = temp_sim();
sux_sim->read_state(state);
merge_fpu_stack(instrs, cur_sim, sux_sim);
} else {
// propagate current FPU stack state to successor without state
// clean up stack first so that there are no dead values on the stack
if (ComputeExactFPURegisterUsage) {
FpuStackSim* cur_sim = sim();
ResourceBitMap live_fpu_regs = block->sux_at(0)->fpu_register_usage();
assert(live_fpu_regs.size() == FrameMap::nof_fpu_regs, "missing register usage");
merge_cleanup_fpu_stack(instrs, cur_sim, live_fpu_regs);
}
intArray* state = sim()->write_state();
if (TraceFPUStack) {
tty->print_cr("Setting FPU stack state of B%d (merge path)", sux->block_id());
sim()->print(); tty->cr();
}
sux->set_fpu_stack_state(state);
}
if (instrs->instructions_list()->length() > 0) {
lir()->insert_before(pos(), instrs);
set_pos(instrs->instructions_list()->length() + pos());
changed = true;
}
} else {
// Propagate unmodified Stack to successors where a stack merge is not necessary
intArray* state = sim()->write_state();
for (int i = 0; i < number_of_sux; i++) {
BlockBegin* sux = block->sux_at(i);
#ifdef ASSERT
for (int j = 0; j < sux->number_of_preds(); j++) {
assert(block == sux->pred_at(j), "all critical edges must be broken");
}
// check if new state is same
if (sux->fpu_stack_state() != NULL) {
intArray* sux_state = sux->fpu_stack_state();
assert(state->length() == sux_state->length(), "overwriting existing stack state");
for (int j = 0; j < state->length(); j++) {
assert(state->at(j) == sux_state->at(j), "overwriting existing stack state");
}
}
#endif
#ifndef PRODUCT
if (TraceFPUStack) {
tty->print_cr("Setting FPU stack state of B%d", sux->block_id());
sim()->print(); tty->cr();
}
#endif
sux->set_fpu_stack_state(state);
}
}
#ifndef PRODUCT
// assertions that FPU stack state conforms to all successors' states
intArray* cur_state = sim()->write_state();
for (int i = 0; i < number_of_sux; i++) {
BlockBegin* sux = block->sux_at(i);
intArray* sux_state = sux->fpu_stack_state();
assert(sux_state != NULL, "no fpu state");
assert(cur_state->length() == sux_state->length(), "incorrect length");
for (int i = 0; i < cur_state->length(); i++) {
assert(cur_state->at(i) == sux_state->at(i), "element not equal");
}
}
#endif
return changed;
}