Revision: 10599
Author: [email protected]
Date: Fri Feb 3 04:48:21 2012
Log: ARM: More micro-optimization of megamorphic lookup.
Review URL: https://chromiumcodereview.appspot.com/9323004
http://code.google.com/p/v8/source/detail?r=10599
Modified:
/branches/bleeding_edge/src/arm/stub-cache-arm.cc
=======================================
--- /branches/bleeding_edge/src/arm/stub-cache-arm.cc Thu Feb 2 05:41:06
2012
+++ /branches/bleeding_edge/src/arm/stub-cache-arm.cc Fri Feb 3 04:48:21
2012
@@ -205,8 +205,9 @@
// 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 @@
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 @@
kSecondary,
name,
scratch,
- kHeapObjectTagSize,
+ 1,
extra,
extra2);
--
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