Reviewers: danno,
Message:
PTAL
Description:
DoNumberTagD performance improvement
Allocate heap entry untagged and tag at end to avoid having to subtract off
the tag offset before storing the value.
BUG=
Please review this at https://codereview.chromium.org/11028115/
SVN Base: git://github.com/v8/v8.git@master
Affected files:
M src/arm/lithium-codegen-arm.cc
M src/arm/macro-assembler-arm.h
M src/arm/macro-assembler-arm.cc
Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index
b5a0f9af31919d948e1ec2fa0fc6f77e47c5013f..52864d3c2b58625ff89bfe3ccb0fbefe9 2b6f831
100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -4491,13 +4491,15 @@ void LCodeGen::DoNumberTagD(LNumberTagD* instr) {
DeferredNumberTagD* deferred = new(zone()) DeferredNumberTagD(this,
instr);
if (FLAG_inline_new) {
__ LoadRoot(scratch, Heap::kHeapNumberMapRootIndex);
- __ AllocateHeapNumber(reg, temp1, temp2, scratch, deferred->entry());
+ // We want the untagged address first for performance
+ __ AllocateHeapNumber(reg, temp1, temp2, scratch, deferred->entry(),
false);
} else {
__ jmp(deferred->entry());
}
__ bind(deferred->exit());
- __ sub(ip, reg, Operand(kHeapObjectTag));
- __ vstr(input_reg, ip, HeapNumber::kValueOffset);
+ __ vstr(input_reg, reg, HeapNumber::kValueOffset);
+ // Now that we have finished with the object's real address tag it
+ __ add(reg, reg, Operand(kHeapObjectTag));
}
@@ -4510,6 +4512,7 @@ void LCodeGen::DoDeferredNumberTagD(LNumberTagD*
instr) {
PushSafepointRegistersScope scope(this, Safepoint::kWithRegisters);
CallRuntimeFromDeferred(Runtime::kAllocateHeapNumber, 0, instr);
+ __ sub(r0, r0, Operand(kHeapObjectTag));
__ StoreToSafepointRegisterSlot(r0, reg);
}
Index: src/arm/macro-assembler-arm.cc
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index
cc7fc4d3a4203706ce0a9cccee63e43d2adbdbb2..a3cb02b4f38338c4bd9de6e642bc4321a 7ea3436
100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -3122,7 +3122,8 @@ void MacroAssembler::AllocateHeapNumber(Register
result,
Register scratch1,
Register scratch2,
Register heap_number_map,
- Label* gc_required) {
+ Label* gc_required,
+ bool tagged) {
// Allocate an object in the heap for the heap number and tag it as a
heap
// object.
AllocateInNewSpace(HeapNumber::kSize,
@@ -3130,11 +3131,15 @@ void MacroAssembler::AllocateHeapNumber(Register
result,
scratch1,
scratch2,
gc_required,
- TAG_OBJECT);
+ tagged?TAG_OBJECT:NO_ALLOCATION_FLAGS);
// Store heap number map in the allocated object.
AssertRegisterIsRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
- str(heap_number_map, FieldMemOperand(result, HeapObject::kMapOffset));
+ if (tagged) {
+ str(heap_number_map, FieldMemOperand(result, HeapObject::kMapOffset));
+ } else {
+ str(heap_number_map, MemOperand(result, HeapObject::kMapOffset));
+ }
}
Index: src/arm/macro-assembler-arm.h
diff --git a/src/arm/macro-assembler-arm.h b/src/arm/macro-assembler-arm.h
index
ff0deef0f46dff25a17eb5cbae7b1ae5c3b0f47b..448259f735322f2f0d14d15b0b84e9fe2 b427eec
100644
--- a/src/arm/macro-assembler-arm.h
+++ b/src/arm/macro-assembler-arm.h
@@ -731,7 +731,8 @@ class MacroAssembler: public Assembler {
Register scratch1,
Register scratch2,
Register heap_number_map,
- Label* gc_required);
+ Label* gc_required,
+ bool tagged = true);
void AllocateHeapNumberWithValue(Register result,
DwVfpRegister value,
Register scratch1,
