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

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

Index: src/compiler/mips/code-generator-mips.cc
diff --git a/src/compiler/mips/code-generator-mips.cc b/src/compiler/mips/code-generator-mips.cc
index 2c5264e498ee2c33dec148e6125c0b44d37a0165..26074af6275f76c43b0b8924235e6075f07776d6 100644
--- a/src/compiler/mips/code-generator-mips.cc
+++ b/src/compiler/mips/code-generator-mips.cc
@@ -120,8 +120,11 @@ class MipsOperandConverter final : public InstructionOperandConverter {
   MemOperand ToMemOperand(InstructionOperand* op) const {
     DCHECK_NOT_NULL(op);
     DCHECK(op->IsStackSlot() || op->IsDoubleStackSlot());
-    FrameOffset offset = frame_access_state()->GetFrameOffset(
-        AllocatedOperand::cast(op)->index());
+    return SlotToMemOperand(AllocatedOperand::cast(op)->index());
+  }
+
+  MemOperand SlotToMemOperand(int slot) const {
+    FrameOffset offset = frame_access_state()->GetFrameOffset(slot);
     return MemOperand(offset.from_stack_pointer() ? sp : fp, offset.offset());
   }
 };
@@ -1703,9 +1706,9 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
         case Constant::kHeapObject: {
           Handle<HeapObject> src_object = src.ToHeapObject();
           Heap::RootListIndex index;
-          int offset;
-          if (IsMaterializableFromFrame(src_object, &offset)) {
-            __ lw(dst, MemOperand(fp, offset));
+          int slot;
+          if (IsMaterializableFromFrame(src_object, &slot)) {
+            __ lw(dst, g.SlotToMemOperand(slot));
           } else if (IsMaterializableFromRoot(src_object, &index)) {
             __ LoadRoot(dst, index);
           } else {