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Fixing dead code in empty array init.

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TEST=set JSArray::kPreallocatedArrayElements to larger than 4.

Review URL: http://codereview.chromium.org/8381014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9816 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
yangguo@chromium.org 2011-10-27 11:11:59 +00:00
parent 9cc75769bc
commit b56466f4da
4 changed files with 40 additions and 19 deletions
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18
src/arm/builtins-arm.cc
View File

@ -104,7 +104,10 @@ static void AllocateEmptyJSArray(MacroAssembler* masm,
// Allocate the JSArray object together with space for a fixed array with the
// requested elements.
int size = JSArray::kSize + FixedArray::SizeFor(initial_capacity);
int size = JSArray::kSize;
if (initial_capacity > 0) {
size += FixedArray::SizeFor(initial_capacity);
}
__ AllocateInNewSpace(size,
result,
scratch2,
@ -124,6 +127,11 @@ static void AllocateEmptyJSArray(MacroAssembler* masm,
__ mov(scratch3, Operand(0, RelocInfo::NONE));
__ str(scratch3, FieldMemOperand(result, JSArray::kLengthOffset));
if (initial_capacity == 0) {
__ str(scratch1, FieldMemOperand(result, JSArray::kElementsOffset));
return;
}
// Calculate the location of the elements array and set elements array member
// of the JSArray.
// result: JSObject
@ -132,7 +140,6 @@ static void AllocateEmptyJSArray(MacroAssembler* masm,
__ str(scratch1, FieldMemOperand(result, JSArray::kElementsOffset));
// Clear the heap tag on the elements array.
STATIC_ASSERT(kSmiTag == 0);
__ sub(scratch1, scratch1, Operand(kHeapObjectTag));
// Initialize the FixedArray and fill it with holes. FixedArray length is
@ -141,15 +148,14 @@ static void AllocateEmptyJSArray(MacroAssembler* masm,
// scratch1: elements array (untagged)
// scratch2: start of next object
__ LoadRoot(scratch3, Heap::kFixedArrayMapRootIndex);
ASSERT_EQ(0 * kPointerSize, FixedArray::kMapOffset);
STATIC_ASSERT(0 * kPointerSize == FixedArray::kMapOffset);
__ str(scratch3, MemOperand(scratch1, kPointerSize, PostIndex));
__ mov(scratch3, Operand(Smi::FromInt(initial_capacity)));
ASSERT_EQ(1 * kPointerSize, FixedArray::kLengthOffset);
STATIC_ASSERT(1 * kPointerSize == FixedArray::kLengthOffset);
__ str(scratch3, MemOperand(scratch1, kPointerSize, PostIndex));
// Fill the FixedArray with the hole value. Inline the code if short.
if (initial_capacity == 0) return;
ASSERT_EQ(2 * kPointerSize, FixedArray::kHeaderSize);
STATIC_ASSERT(2 * kPointerSize == FixedArray::kHeaderSize);
__ LoadRoot(scratch3, Heap::kTheHoleValueRootIndex);
static const int kLoopUnfoldLimit = 4;
if (initial_capacity <= kLoopUnfoldLimit) {

12
src/ia32/builtins-ia32.cc
View File

@ -996,13 +996,17 @@ static void AllocateEmptyJSArray(MacroAssembler* masm,
}
} else {
Label loop, entry;
__ mov(scratch2, Immediate(initial_capacity));
__ jmp(&entry);
__ bind(&loop);
__ mov(Operand(scratch1, 0), factory->the_hole_value());
__ add(scratch1, Immediate(kPointerSize));
__ mov(FieldOperand(scratch1,
scratch2,
times_pointer_size,
FixedArray::kHeaderSize),
factory->the_hole_value());
__ bind(&entry);
__ cmp(scratch1, scratch2);
__ j(below, &loop);
__ dec(scratch2);
__ j(not_sign, &loop);
}
}

17
src/mips/builtins-mips.cc
View File

@ -106,7 +106,10 @@ static void AllocateEmptyJSArray(MacroAssembler* masm,
// Allocate the JSArray object together with space for a fixed array with the
// requested elements.
int size = JSArray::kSize + FixedArray::SizeFor(initial_capacity);
int size = JSArray::kSize;
if (initial_capacity > 0) {
size += FixedArray::SizeFor(initial_capacity);
}
__ AllocateInNewSpace(size,
result,
scratch2,
@ -125,6 +128,11 @@ static void AllocateEmptyJSArray(MacroAssembler* masm,
__ mov(scratch3, zero_reg);
__ sw(scratch3, FieldMemOperand(result, JSArray::kLengthOffset));
if (initial_capacity == 0) {
__ sw(scratch1, FieldMemOperand(result, JSArray::kElementsOffset));
return;
}
// Calculate the location of the elements array and set elements array member
// of the JSArray.
// result: JSObject
@ -141,17 +149,16 @@ static void AllocateEmptyJSArray(MacroAssembler* masm,
// scratch1: elements array (untagged)
// scratch2: start of next object
__ LoadRoot(scratch3, Heap::kFixedArrayMapRootIndex);
ASSERT_EQ(0 * kPointerSize, FixedArray::kMapOffset);
STATIC_ASSERT(0 * kPointerSize == FixedArray::kMapOffset);
__ sw(scratch3, MemOperand(scratch1));
__ Addu(scratch1, scratch1, kPointerSize);
__ li(scratch3, Operand(Smi::FromInt(initial_capacity)));
ASSERT_EQ(1 * kPointerSize, FixedArray::kLengthOffset);
STATIC_ASSERT(1 * kPointerSize == FixedArray::kLengthOffset);
__ sw(scratch3, MemOperand(scratch1));
__ Addu(scratch1, scratch1, kPointerSize);
// Fill the FixedArray with the hole value. Inline the code if short.
if (initial_capacity == 0) return;
ASSERT_EQ(2 * kPointerSize, FixedArray::kHeaderSize);
STATIC_ASSERT(2 * kPointerSize == FixedArray::kHeaderSize);
__ LoadRoot(scratch3, Heap::kTheHoleValueRootIndex);
static const int kLoopUnfoldLimit = 4;
if (initial_capacity <= kLoopUnfoldLimit) {

12
src/x64/builtins-x64.cc
View File

@ -1075,13 +1075,17 @@ static void AllocateEmptyJSArray(MacroAssembler* masm,
}
} else {
Label loop, entry;
__ movq(scratch2, Immediate(initial_capacity));
__ jmp(&entry);
__ bind(&loop);
__ movq(Operand(scratch1, 0), scratch3);
__ addq(scratch1, Immediate(kPointerSize));
__ movq(FieldOperand(scratch1,
scratch2,
times_pointer_size,
FixedArray::kHeaderSize),
scratch3);
__ bind(&entry);
__ cmpq(scratch1, scratch2);
__ j(below, &loop);
__ decq(scratch2);
__ j(not_sign, &loop);
}
}