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X87: change the float max/min operation when operands.

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This CL fixes the following situations:
    1, Operands are -0.0 or 0.0. it always return right value.
    1, Operands contains NaN. it always return right value.

BUG=

Review URL: https://codereview.chromium.org/1214893004

Cr-Commit-Position: refs/heads/master@{#29407}
This commit is contained in:
chunyang.dai 2015-07-01 04:29:00 -07:00 committed by Commit bot
parent aaa92726f0
commit 68020ce546
1 changed files with 8 additions and 37 deletions
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45
src/compiler/x87/code-generator-x87.cc
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@ -766,7 +766,7 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
break;
}
case kX87Float64Max: {
Label check_nan_left, check_zero, return_left, return_right;
Label check_zero, return_left, return_right;
Condition condition = below;
__ fstp(0);
__ fld_d(MemOperand(esp, kDoubleSize));
@ -774,8 +774,9 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
__ fld(1);
__ fld(1);
__ FCmp();
__ j(parity_even, &check_nan_left, Label::kNear); // At least one NaN.
__ j(equal, &check_zero, Label::kNear); // left == right.
__ j(parity_even, &return_right,
Label::kNear); // At least one NaN, Return right.
__ j(equal, &check_zero, Label::kNear); // left == right.
__ j(condition, &return_left, Label::kNear);
__ jmp(&return_right, Label::kNear);
@ -785,15 +786,6 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
__ FCmp();
__ j(not_equal, &return_left, Label::kNear); // left == right != 0.
__ fadd(1);
__ jmp(&return_left, Label::kNear);
__ bind(&check_nan_left);
__ fld(0);
__ fld(0);
__ FCmp(); // NaN check.
__ j(parity_even, &return_left, Label::kNear); // left == NaN.
__ bind(&return_right);
__ fxch();
@ -803,7 +795,7 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
break;
}
case kX87Float64Min: {
Label check_nan_left, check_zero, return_left, return_right;
Label check_zero, return_left, return_right;
Condition condition = above;
__ fstp(0);
__ fld_d(MemOperand(esp, kDoubleSize));
@ -811,8 +803,9 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
__ fld(1);
__ fld(1);
__ FCmp();
__ j(parity_even, &check_nan_left, Label::kNear); // At least one NaN.
__ j(equal, &check_zero, Label::kNear); // left == right.
__ j(parity_even, &return_right,
Label::kNear); // At least one NaN, return right value.
__ j(equal, &check_zero, Label::kNear); // left == right.
__ j(condition, &return_left, Label::kNear);
__ jmp(&return_right, Label::kNear);
@ -821,28 +814,6 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
__ fldz();
__ FCmp();
__ j(not_equal, &return_left, Label::kNear); // left == right != 0.
// At this point, both left and right are either 0 or -0.
// Push st0 and st1 to stack, then pop them to temp registers and OR them,
// load it to left.
__ push(eax);
__ fld(1);
__ fld(1);
__ sub(esp, Immediate(2 * kPointerSize));
__ fstp_s(MemOperand(esp, 0));
__ fstp_s(MemOperand(esp, kPointerSize));
__ pop(eax);
__ xor_(MemOperand(esp, 0), eax);
__ fstp(0);
__ fld_s(MemOperand(esp, 0));
__ pop(eax); // restore esp
__ pop(eax); // restore esp
__ jmp(&return_left, Label::kNear);
__ bind(&check_nan_left);
__ fld(0);
__ fld(0);
__ FCmp(); // NaN check.
__ j(parity_even, &return_left, Label::kNear); // left == NaN.
__ bind(&return_right);
__ fxch();