Fix write barrier for StoreKeyedFastElements on ARM

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index d915c7d247bb9d13248840f43ae841e2be4ddd8b..84e9fc530f40cf66db79012e0e81ae32832ee4af 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -3851,13 +3851,14 @@ void LCodeGen::DoStoreKeyedFastElement(LStoreKeyedFastElement* instr) {
   Register scratch = scratch0();
 
   // Do the store.
+  int offset = 0;
+  Register store_base = scratch;
   if (instr->key()->IsConstantOperand()) {
     ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
     LConstantOperand* const_operand = LConstantOperand::cast(instr->key());
-    int offset =
-        (ToInteger32(const_operand) + instr->additional_index()) * kPointerSize
-        + FixedArray::kHeaderSize;
-    __ str(value, FieldMemOperand(elements, offset));
+    offset = (ToInteger32(const_operand) + instr->additional_index()) *

[Michael Starzinger, 2012/07/31 13:42:32]

Can we use FixedArray::OffsetOfElementAt() for this?

+        kPointerSize + FixedArray::kHeaderSize;
+    store_base = elements;
   } else {
     // Even though the HLoadKeyedFastElement instruction forces the input
     // representation for the key to be an integer, the input gets replaced
@@ -3869,17 +3870,17 @@ void LCodeGen::DoStoreKeyedFastElement(LStoreKeyedFastElement* instr) {
     } else {
       __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2));
     }
-    uint32_t offset = FixedArray::kHeaderSize +
+    offset = FixedArray::kHeaderSize +
         (instr->additional_index() << kPointerSizeLog2);
-    __ str(value, FieldMemOperand(scratch, offset));
   }
+  __ str(value, FieldMemOperand(store_base, offset));
 
   if (instr->hydrogen()->NeedsWriteBarrier()) {
     HType type = instr->hydrogen()->value()->type();
     SmiCheck check_needed =
         type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     // Compute address of modified element and store it into key register.
-    __ add(key, scratch, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
+    __ add(key, store_base, Operand(offset - kHeapObjectTag));
     __ RecordWrite(elements,
                    key,
                    value,