Reviewers: jochen,
Description:
A64: Port recent ARM optimizations in LCodeGen::DoAccessArgumentsAt.
[email protected]
Please review this at https://codereview.chromium.org/172333004/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+21, -19 lines):
M src/a64/lithium-a64.h
M src/a64/lithium-a64.cc
M src/a64/lithium-codegen-a64.cc
Index: src/a64/lithium-a64.cc
diff --git a/src/a64/lithium-a64.cc b/src/a64/lithium-a64.cc
index
3857ca7fc352157d738927885a214bcbb23323dc..d9f51e2edb49bb3bbe45216cc25e8aa0296fa7ff
100644
--- a/src/a64/lithium-a64.cc
+++ b/src/a64/lithium-a64.cc
@@ -812,12 +812,10 @@ LInstruction*
LChunkBuilder::DoBoundsCheckBaseIndexInformation(
LInstruction* LChunkBuilder::DoAccessArgumentsAt(HAccessArgumentsAt*
instr) {
- // TODO(all): Try to improve this, like ARM r17925.
info()->MarkAsRequiresFrame();
LOperand* args = NULL;
LOperand* length = NULL;
LOperand* index = NULL;
- LOperand* temp = NULL;
if (instr->length()->IsConstant() && instr->index()->IsConstant()) {
args = UseRegisterAtStart(instr->arguments());
@@ -827,11 +825,9 @@ LInstruction*
LChunkBuilder::DoAccessArgumentsAt(HAccessArgumentsAt* instr) {
args = UseRegister(instr->arguments());
length = UseRegisterAtStart(instr->length());
index = UseRegisterOrConstantAtStart(instr->index());
- temp = TempRegister();
}
- return DefineAsRegister(
- new(zone()) LAccessArgumentsAt(args, length, index, temp));
+ return DefineAsRegister(new(zone()) LAccessArgumentsAt(args, length,
index));
}
Index: src/a64/lithium-a64.h
diff --git a/src/a64/lithium-a64.h b/src/a64/lithium-a64.h
index
59ae9be62139128fcd838ce9d74cfe2978ff68a1..26234e92429f0fadfc0eb64b32cefd5ec253acc2
100644
--- a/src/a64/lithium-a64.h
+++ b/src/a64/lithium-a64.h
@@ -541,16 +541,14 @@ class LOsrEntry V8_FINAL : public
LTemplateInstruction<0, 0, 0> {
};
-class LAccessArgumentsAt V8_FINAL : public LTemplateInstruction<1, 3, 1> {
+class LAccessArgumentsAt V8_FINAL : public LTemplateInstruction<1, 3, 0> {
public:
LAccessArgumentsAt(LOperand* arguments,
LOperand* length,
- LOperand* index,
- LOperand* temp) {
+ LOperand* index) {
inputs_[0] = arguments;
inputs_[1] = length;
inputs_[2] = index;
- temps_[0] = temp;
}
DECLARE_CONCRETE_INSTRUCTION(AccessArgumentsAt, "access-arguments-at")
@@ -558,7 +556,6 @@ class LAccessArgumentsAt V8_FINAL : public
LTemplateInstruction<1, 3, 1> {
LOperand* arguments() { return inputs_[0]; }
LOperand* length() { return inputs_[1]; }
LOperand* index() { return inputs_[2]; }
- LOperand* temp() { return temps_[0]; }
virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
};
Index: src/a64/lithium-codegen-a64.cc
diff --git a/src/a64/lithium-codegen-a64.cc b/src/a64/lithium-codegen-a64.cc
index
033a439513672589c0727811ac25f47fd4d984a6..11ee500c4b37eeba9996e8daefb59012dcadd729
100644
--- a/src/a64/lithium-codegen-a64.cc
+++ b/src/a64/lithium-codegen-a64.cc
@@ -1404,27 +1404,36 @@ void LCodeGen::DoGap(LGap* gap) {
void LCodeGen::DoAccessArgumentsAt(LAccessArgumentsAt* instr) {
- // TODO(all): Try to improve this, like ARM r17925.
Register arguments = ToRegister(instr->arguments());
Register result = ToRegister(instr->result());
+ // The pointer to the arguments array come from DoArgumentsElements.
+ // It does not point directly to the arguments and there is an offest of
+ // two words that we must take into account when accessing an argument.
+ // Subtracting the index from length accounts for one, so we add one
more.
+
if (instr->length()->IsConstantOperand() &&
instr->index()->IsConstantOperand()) {
- ASSERT(instr->temp() == NULL);
int index = ToInteger32(LConstantOperand::cast(instr->index()));
int length = ToInteger32(LConstantOperand::cast(instr->length()));
int offset = ((length - index) + 1) * kPointerSize;
__ Ldr(result, MemOperand(arguments, offset));
+ } else if (instr->index()->IsConstantOperand()) {
+ Register length = ToRegister32(instr->length());
+ int index = ToInteger32(LConstantOperand::cast(instr->index()));
+ int loc = index - 1;
+ if (loc != 0) {
+ __ Sub(result.W(), length, loc);
+ __ Ldr(result, MemOperand(arguments, result, UXTW,
kPointerSizeLog2));
+ } else {
+ __ Ldr(result, MemOperand(arguments, length, UXTW,
kPointerSizeLog2));
+ }
} else {
- ASSERT(instr->temp() != NULL);
- Register temp = ToRegister32(instr->temp());
Register length = ToRegister32(instr->length());
Operand index = ToOperand32I(instr->index());
- // There are two words between the frame pointer and the last
arguments.
- // Subtracting from length accounts for only one, so we add one more.
- __ Sub(temp, length, index);
- __ Add(temp, temp, 1);
- __ Ldr(result, MemOperand(arguments, temp, UXTW, kPointerSizeLog2));
+ __ Sub(result.W(), length, index);
+ __ Add(result.W(), result.W(), 1);
+ __ Ldr(result, MemOperand(arguments, result, UXTW, kPointerSizeLog2));
}
}
--
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