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Skip check for +/-0.5 in optimized Math.pow (ia32).

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Review URL: http://codereview.chromium.org/8820007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10168 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
yangguo@chromium.org 2011-12-06 09:20:28 +00:00
parent fe2049fcb8
commit 5e432754b3
1 changed files with 35 additions and 30 deletions
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7
src/ia32/code-stubs-ia32.cc
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@ -3025,7 +3025,11 @@ void MathPowStub::Generate(MacroAssembler* masm) {
__ ucomisd(xmm2, xmm4);
__ j(equal, &int_exponent);
// Detect square root case.
if (exponent_type_ == ON_STACK) {
// Detect square root case. Crankshaft detects constant +/-0.5 at
// compile time and uses DoMathPowHalf instead. We then skip this check
// for non-constant cases of +/-0.5 as these hardly occur.
// Test for -0.5.
// Load xmm4 with -0.5.
__ mov(ecx, Immediate(0xBF000000u));
@ -3057,6 +3061,7 @@ void MathPowStub::Generate(MacroAssembler* masm) {
__ addsd(xmm4, xmm1);
__ sqrtsd(xmm3, xmm4);
__ jmp(&done);
}
// Using FPU instructions to calculate power.
Label fast_power_failed;