Improve constant element index access code generation

src/ia32/lithium-codegen-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2687 matching lines @@
 
 Operand LCodeGen::BuildFastArrayOperand(
     LOperand* elements_pointer,
     LOperand* key,
     Representation key_representation,
     ElementsKind elements_kind,
     uint32_t offset,
     uint32_t additional_index) {
   Register elements_pointer_reg = ToRegister(elements_pointer);
   int shift_size = ElementsKindToShiftSize(elements_kind);
+  // Even though the HLoad/StoreKeyedFastElement instructions force the input
+  // representation for the key to be an integer, the input gets replaced during
+  // bound check elimination with the index argument to the bounds check, which
+  // can be tagged, so that case must be handled here, too.
   if (key_representation.IsTagged() && (shift_size >= 1)) {
     shift_size -= kSmiTagSize;
   }
   if (key->IsConstantOperand()) {
     int constant_value = ToInteger32(LConstantOperand::cast(key));
     if (constant_value & 0xF0000000) {
       Abort("array index constant value too big");
     }
     return Operand(elements_pointer_reg,
                    ((constant_value + additional_index) << shift_size)
@@ skipping 956 matching lines @@
   __ mov(ecx, instr->name());
   Handle<Code> ic = (instr->strict_mode_flag() == kStrictMode)
       ? isolate()->builtins()->StoreIC_Initialize_Strict()
       : isolate()->builtins()->StoreIC_Initialize();
   CallCode(ic, RelocInfo::CODE_TARGET, instr);
 }
 
 
 void LCodeGen::DoBoundsCheck(LBoundsCheck* instr) {
   if (instr->index()->IsConstantOperand()) {
-    __ cmp(ToOperand(instr->length()),
-           Immediate(ToInteger32(LConstantOperand::cast(instr->index()))));
+    int constant_index =
+        ToInteger32(LConstantOperand::cast(instr->index()));
+    if (instr->hydrogen()->length()->representation().IsTagged()) {
+      __ cmp(ToOperand(instr->length()),
+             Immediate(Smi::FromInt(constant_index)));
+    } else {
+      __ cmp(ToOperand(instr->length()), Immediate(constant_index));
+    }
     DeoptimizeIf(below_equal, instr->environment());
   } else {
     __ cmp(ToRegister(instr->index()), ToOperand(instr->length()));
     DeoptimizeIf(above_equal, instr->environment());
   }
 }
 
 
 void LCodeGen::DoStoreKeyedSpecializedArrayElement(
     LStoreKeyedSpecializedArrayElement* instr) {
@@ skipping 1663 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32