MIPS: Improvements in lithium code generation. Recognizing if some operands are constants, we can o…

src/mips/lithium-mips.cc

Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index fb8826b7f358eb0638205fd150593077c2d64b38..41487f6d744149a3702f066707ad4f1e75ba6b66 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -2340,8 +2340,15 @@ LInstruction* LChunkBuilder::DoArgumentsObject(HArgumentsObject* instr) {
 LInstruction* LChunkBuilder::DoAccessArgumentsAt(HAccessArgumentsAt* instr) {
   info()->MarkAsRequiresFrame();
   LOperand* args = UseRegister(instr->arguments());
-  LOperand* length = UseTempRegister(instr->length());
-  LOperand* index = UseRegister(instr->index());
+  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 = Use(instr->index());
+  }
   return DefineAsRegister(new(zone()) LAccessArgumentsAt(args, length, index));
 }