Use immediates when possible for HBoundsCheck and HLoadKeyedFastElement

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index c0f4e71caa4a42cd0f2bb7033204762997275960..93299250ae85d51c742653c6145b35fbf4aaaf34 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -2303,15 +2303,19 @@ void LCodeGen::DoAccessArgumentsAt(LAccessArgumentsAt* instr) {
 
 void LCodeGen::DoLoadKeyedFastElement(LLoadKeyedFastElement* instr) {
   Register elements = ToRegister(instr->elements());
-  Register key = ToRegister(instr->key());
   Register result = ToRegister(instr->result());
-  ASSERT(result.is(elements));
 
   // Load the result.
-  __ mov(result, FieldOperand(elements,
-                              key,
-                              times_pointer_size,
-                              FixedArray::kHeaderSize));
+  if (instr->key()->IsConstantOperand()) {
+    int key = ToInteger32(LConstantOperand::cast(instr->key()));
+    __ mov(result, FieldOperand(
+        elements, (key << times_pointer_size) + FixedArray::kHeaderSize));

[danno, 2011/08/10 11:03:46]

overflow check in the spirit of lithium-codegen-ia32.cc:51? Also in the 64-bit
version?

[Jakob Kummerow, 2011/08/10 12:22:48]

Done (by using BuildFastArrayOperand).

+  } else {
+    __ mov(result, FieldOperand(elements,
+                                ToRegister(instr->key()),
+                                times_pointer_size,
+                                FixedArray::kHeaderSize));
+  }
 
   // Check for the hole value.
   if (instr->hydrogen()->RequiresHoleCheck()) {
@@ -3108,8 +3112,14 @@ void LCodeGen::DoStoreNamedGeneric(LStoreNamedGeneric* instr) {
 
 
 void LCodeGen::DoBoundsCheck(LBoundsCheck* instr) {
-  __ cmp(ToRegister(instr->index()), ToOperand(instr->length()));
-  DeoptimizeIf(above_equal, instr->environment());
+  if (instr->index()->IsConstantOperand()) {
+    __ cmp(ToOperand(instr->length()),
+           ToImmediate(LConstantOperand::cast(instr->index())));
+    DeoptimizeIf(below_equal, instr->environment());

[danno, 2011/08/10 11:03:46]

overflow check in the spirit of lithium-codegen-ia32.cc:51? Also in the 64-bit
version?

[Jakob Kummerow, 2011/08/10 12:22:48]

As discussed offline, nothing to overflow-check here.

+  } else {
+    __ cmp(ToRegister(instr->index()), ToOperand(instr->length()));
+    DeoptimizeIf(above_equal, instr->environment());
+  }
 }