[turbofan] Add an operator to access the parent frame pointer

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 05d53af12b59b8c1579b62dc6bdc16810ff26d51..70dca3600c2826892dabf0df846b164ffdb3f577 100644
--- a/src/compiler/mips/code-generator-mips.cc
+++ b/src/compiler/mips/code-generator-mips.cc
@@ -604,6 +604,13 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kArchFramePointer:
       __ mov(i.OutputRegister(), fp);
       break;
+    case kArchParentFramePointer:
+      if (frame_access_state()->frame()->needs_frame()) {
+        __ lw(i.OutputRegister(), MemOperand(fp, 0));
+      } else {
+        __ mov(i.OutputRegister(), fp);
+      }
+      break;
     case kArchTruncateDoubleToI:
       __ TruncateDoubleToI(i.OutputRegister(), i.InputDoubleRegister(0));
       break;