Reviewers: Mads Ager,
Message:
Small change.
Description:
X64: Update allocation to work with no scratch registers at all.
Please review this at http://codereview.chromium.org/1856001/show
Affected files:
M src/x64/macro-assembler-x64.h
M src/x64/macro-assembler-x64.cc
Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index
d706fc1acd230f37e940c50a4e0b44dcb689123f..ec0456f3dd731116beca54389ae7cdf00f14d9bb
100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -2335,7 +2335,7 @@ 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);
@@ -2346,9 +2346,13 @@ 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);
@@ -2373,7 +2377,7 @@ 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 {
@@ -2397,16 +2401,25 @@ 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));
}
}
Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index
59b19fdadaa25aa38dd4c63f62ddfa3565e968d6..0bfe73031c14d912227cfc75718cc12f187cc207
100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -770,10 +770,17 @@ 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);
};
--
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