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ARM: More micro-optimization of megamorphic lookup.

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Review URL: https://chromiumcodereview.appspot.com/9323004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10599 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
erik.corry@gmail.com 2012-02-03 12:48:21 +00:00
parent aa4b77d761
commit 039223af9a
1 changed files with 9 additions and 7 deletions
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16
src/arm/stub-cache-arm.cc
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@ -205,8 +205,9 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
// Mask down the eor argument to the minimum to keep the immediate
// ARM-encodable.
__ eor(scratch, scratch, Operand(flags & mask));
// Prefer ubfx to and_ here because the mask is not ARM-encodable.
__ Ubfx(scratch, scratch, kHeapObjectTagSize, kPrimaryTableBits);
// Prefer and_ to ubfx here because ubfx takes 2 cycles.
__ and_(scratch, scratch, Operand(mask));
__ mov(scratch, Operand(scratch, LSR, 1));
// Probe the primary table.
ProbeTable(isolate,
@ -215,14 +216,15 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
kPrimary,
name,
scratch,
kHeapObjectTagSize,
1,
extra,
extra2);
// Primary miss: Compute hash for secondary probe.
__ rsb(scratch, name, Operand(scratch, LSL, kHeapObjectTagSize));
__ add(scratch, scratch, Operand(flags));
__ Ubfx(scratch, scratch, kHeapObjectTagSize, kSecondaryTableBits);
__ sub(scratch, scratch, Operand(name, LSR, 1));
uint32_t mask2 = (kSecondaryTableSize - 1) << (kHeapObjectTagSize - 1);
__ add(scratch, scratch, Operand((flags >> 1) & mask2));
__ and_(scratch, scratch, Operand(mask2));
// Probe the secondary table.
ProbeTable(isolate,
@ -231,7 +233,7 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
kSecondary,
name,
scratch,
kHeapObjectTagSize,
1,
extra,
extra2);