Improvements in lithium code generation. Recognizing if some operands are constants, we can often s…

src/arm/lithium-arm.cc

Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index 64083e8597381c7549a356bb79e253cc6a8f13c5..8039b5ac0ecaeeea5bfb35aea06636d7c3bb6814 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -2457,8 +2457,15 @@ LInstruction* LChunkBuilder::DoArgumentsObject(HArgumentsObject* instr) {
 
 LInstruction* LChunkBuilder::DoAccessArgumentsAt(HAccessArgumentsAt* instr) {
   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));
 }