[turbofan] Fix operand calculation for constant materialization from frame.

src/compiler/x64/code-generator-x64.cc

Index: src/compiler/x64/code-generator-x64.cc
diff --git a/src/compiler/x64/code-generator-x64.cc b/src/compiler/x64/code-generator-x64.cc
index ffc9620543dc9e744cbf2df3ad342896ee8ea641..28966253210c4df158d015e71c3d16f3022fb2a0 100644
--- a/src/compiler/x64/code-generator-x64.cc
+++ b/src/compiler/x64/code-generator-x64.cc
@@ -49,8 +49,11 @@ class X64OperandConverter : public InstructionOperandConverter {
 
   Operand ToOperand(InstructionOperand* op, int extra = 0) {
     DCHECK(op->IsStackSlot() || op->IsDoubleStackSlot());
-    FrameOffset offset = frame_access_state()->GetFrameOffset(
-        AllocatedOperand::cast(op)->index());
+    return SlotToOperand(AllocatedOperand::cast(op)->index());
+  }
+
+  Operand SlotToOperand(int slot_index, int extra = 0) {
+    FrameOffset offset = frame_access_state()->GetFrameOffset(slot_index);
     return Operand(offset.from_stack_pointer() ? rsp : rbp,
                    offset.offset() + extra);
   }
@@ -2082,9 +2085,9 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
         case Constant::kHeapObject: {
           Handle<HeapObject> src_object = src.ToHeapObject();
           Heap::RootListIndex index;
-          int offset;
-          if (IsMaterializableFromFrame(src_object, &offset)) {
-            __ movp(dst, Operand(rbp, offset));
+          int slot;
+          if (IsMaterializableFromFrame(src_object, &slot)) {
+            __ movp(dst, g.SlotToOperand(slot));
           } else if (IsMaterializableFromRoot(src_object, &index)) {
             __ LoadRoot(dst, index);
           } else {