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

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

Index: src/compiler/ppc/code-generator-ppc.cc
diff --git a/src/compiler/ppc/code-generator-ppc.cc b/src/compiler/ppc/code-generator-ppc.cc
index 976519eca2457c19d394ca6428f8d0ed1846b238..624afad8e9ba3f7fe0c134ce93e196b793101585 100644
--- a/src/compiler/ppc/code-generator-ppc.cc
+++ b/src/compiler/ppc/code-generator-ppc.cc
@@ -104,8 +104,11 @@ class PPCOperandConverter 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());
   }
 };
@@ -1832,9 +1835,9 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
         case Constant::kHeapObject: {
           Handle<HeapObject> src_object = src.ToHeapObject();
           Heap::RootListIndex index;
-          int offset;
-          if (IsMaterializableFromFrame(src_object, &offset)) {
-            __ LoadP(dst, MemOperand(fp, offset));
+          int slot;
+          if (IsMaterializableFromFrame(src_object, &slot)) {
+            __ LoadP(dst, g.SlotToMemOperand(slot));
           } else if (IsMaterializableFromRoot(src_object, &index)) {
             __ LoadRoot(dst, index);
           } else {