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X64: Update allocation to work with no scratch registers at all.

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Review URL: http://codereview.chromium.org/1856001

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4559 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
lrn@chromium.org 2010-05-03 07:44:55 +00:00
parent 1a750a2110
commit c815de4f52
2 changed files with 30 additions and 10 deletions
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33
src/x64/macro-assembler-x64.cc
View File

@ -2346,7 +2346,7 @@ void MacroAssembler::LoadAllocationTopHelper(Register result,
// Just return if allocation top is already known.
if ((flags & RESULT_CONTAINS_TOP) != 0) {
// No use of scratch if allocation top is provided.
ASSERT(scratch.is(no_reg));
ASSERT(!scratch.is_valid());
#ifdef DEBUG
// Assert that result actually contains top on entry.
movq(kScratchRegister, new_space_allocation_top);
@ -2357,9 +2357,13 @@ void MacroAssembler::LoadAllocationTopHelper(Register result,
}
// Move address of new object to result. Use scratch register if available.
if (scratch.is(no_reg)) {
movq(kScratchRegister, new_space_allocation_top);
movq(result, Operand(kScratchRegister, 0));
if (!scratch.is_valid()) {
if (result.is(rax)) {
load_rax(new_space_allocation_top);
} else {
movq(kScratchRegister, new_space_allocation_top);
movq(result, Operand(kScratchRegister, 0));
}
} else {
ASSERT(!scratch.is(result_end));
movq(scratch, new_space_allocation_top);
@ -2384,7 +2388,7 @@ void MacroAssembler::UpdateAllocationTopHelper(Register result_end,
store_rax(new_space_allocation_top);
} else {
// Register required - use scratch provided if available.
if (scratch.is(no_reg)) {
if (!scratch.is_valid()) {
movq(kScratchRegister, new_space_allocation_top);
movq(Operand(kScratchRegister, 0), result_end);
} else {
@ -2408,16 +2412,25 @@ void MacroAssembler::AllocateInNewSpace(int object_size,
// Calculate new top and bail out if new space is exhausted.
ExternalReference new_space_allocation_limit =
ExternalReference::new_space_allocation_limit_address();
lea(result_end, Operand(result, object_size));
Register top_reg = result_end.is_valid() ? result_end : result;
lea(top_reg, Operand(result, object_size));
movq(kScratchRegister, new_space_allocation_limit);
cmpq(result_end, Operand(kScratchRegister, 0));
cmpq(top_reg, Operand(kScratchRegister, 0));
j(above, gc_required);
// Update allocation top.
UpdateAllocationTopHelper(result_end, scratch);
UpdateAllocationTopHelper(top_reg, scratch);
// Tag the result if requested.
if ((flags & TAG_OBJECT) != 0) {
if (top_reg.is(result)) {
if ((flags & TAG_OBJECT) != 0) {
subq(result, Immediate(object_size - kHeapObjectTag));
} else {
subq(result, Immediate(object_size));
}
} else if ((flags & TAG_OBJECT) != 0) {
// Tag the result if requested.
addq(result, Immediate(kHeapObjectTag));
}
}

7
src/x64/macro-assembler-x64.h
View File

@ -778,10 +778,17 @@ class MacroAssembler: public Assembler {
void LeaveFrame(StackFrame::Type type);
// Allocation support helpers.
// Loads the top of new-space into the result register.
// If flags contains RESULT_CONTAINS_TOP then result_end is valid and
// already contains the top of new-space, and scratch is invalid.
// Otherwise the address of the new-space top is loaded into scratch (if
// scratch is valid), and the new-space top is loaded into result.
void LoadAllocationTopHelper(Register result,
Register result_end,
Register scratch,
AllocationFlags flags);
// Update allocation top with value in result_end register.
// If scratch is valid, it contains the address of the allocation top.
void UpdateAllocationTopHelper(Register result_end, Register scratch);
};