Reviewers: danno, Paul Lind, dusmil, kisg, palfia, m.m.capewell,
Description:
MIPS: Optimize AccessArgumentsAt.
Port r17923 (837f909)
Original commit message:
Optimize register constraints and code generated for AccessArgumentsAt
Lithium
instruction.
BUG=
Please review this at https://codereview.chromium.org/79143007/
SVN Base: https://github.com/v8/v8.git@gbl
Affected files (+36, -21 lines):
M src/mips/lithium-codegen-mips.cc
M src/mips/lithium-mips.cc
Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc
b/src/mips/lithium-codegen-mips.cc
index
e40021dfeab574f4e883c6b7b1eae41c2e0ec79c..5a8249efc3bcd27a23b3b8d80265b48897cca3fc
100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -3037,22 +3037,44 @@ void LCodeGen::DoLoadExternalArrayPointer(
void LCodeGen::DoAccessArgumentsAt(LAccessArgumentsAt* instr) {
Register arguments = ToRegister(instr->arguments());
Register result = ToRegister(instr->result());
- if (instr->length()->IsConstantOperand() &&
- instr->index()->IsConstantOperand()) {
- int const_index = ToInteger32(LConstantOperand::cast(instr->index()));
+ // There are two words between the frame pointer and the last argument.
+ // Subtracting from length accounts for one of them add one more.
+ if (instr->length()->IsConstantOperand()) {
int const_length =
ToInteger32(LConstantOperand::cast(instr->length()));
- int index = (const_length - const_index) + 1;
- __ lw(result, MemOperand(arguments, index * kPointerSize));
+ if (instr->index()->IsConstantOperand()) {
+ int const_index =
ToInteger32(LConstantOperand::cast(instr->index()));
+ int index = (const_length - const_index) + 1;
+ __ lw(result, MemOperand(arguments, index * kPointerSize));
+ } else {
+ Register index = ToRegister(instr->index());
+ __ li(at, Operand(const_length + 1));
+ __ Subu(result, at, index);
+ __ sll(at, result, kPointerSizeLog2);
+ __ Addu(at, arguments, at);
+ __ lw(result, MemOperand(at));
+ }
+ } else if (instr->index()->IsConstantOperand()) {
+ Register length = ToRegister(instr->length());
+ int const_index = ToInteger32(LConstantOperand::cast(instr->index()));
+ int loc = const_index - 1;
+ if (loc != 0) {
+ __ Subu(result, length, Operand(loc));
+ __ sll(at, result, kPointerSizeLog2);
+ __ Addu(at, arguments, at);
+ __ lw(result, MemOperand(at));
+ } else {
+ __ sll(at, length, kPointerSizeLog2);
+ __ Addu(at, arguments, at);
+ __ lw(result, MemOperand(at));
+ }
} else {
Register length = ToRegister(instr->length());
Register index = ToRegister(instr->index());
- // There are two words between the frame pointer and the last argument.
- // Subtracting from length accounts for one of them, add one more.
- __ subu(length, length, index);
- __ Addu(length, length, Operand(1));
- __ sll(length, length, kPointerSizeLog2);
- __ Addu(at, arguments, Operand(length));
- __ lw(result, MemOperand(at, 0));
+ __ Subu(result, length, index);
+ __ Addu(result, result, 1);
+ __ sll(at, result, kPointerSizeLog2);
+ __ Addu(at, arguments, at);
+ __ lw(result, MemOperand(at));
}
}
Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index
fa653c6436e8bb0a426fac3d073eb30df25246e4..34e5838557a0ee528fad7b574c42be8aad570f08
100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -2459,15 +2459,8 @@ LInstruction*
LChunkBuilder::DoCapturedObject(HCapturedObject* instr) {
LInstruction* LChunkBuilder::DoAccessArgumentsAt(HAccessArgumentsAt*
instr) {
info()->MarkAsRequiresFrame();
LOperand* args = UseRegister(instr->arguments());
- LOperand* length;
- LOperand* index;
- if (instr->length()->IsConstant() && instr->index()->IsConstant()) {
- length = UseRegisterOrConstant(instr->length());
- index = UseOrConstant(instr->index());
- } else {
- length = UseTempRegister(instr->length());
- index = UseRegisterAtStart(instr->index());
- }
+ LOperand* length = UseRegisterOrConstantAtStart(instr->length());
+ LOperand* index = UseRegisterOrConstantAtStart(instr->index());
return DefineAsRegister(new(zone()) LAccessArgumentsAt(args, length,
index));
}
--
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