MIPS: Fix register clobbering in LoadIC for interceptors.

src/mips/stub-cache-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1269 matching lines @@
 
   if (compile_followup_inline) {
     // Compile the interceptor call, followed by inline code to load the
     // property from further up the prototype chain if the call fails.
     // Check that the maps haven't changed.
     Register holder_reg = CheckPrototypes(object, receiver, interceptor_holder,
                                           scratch1, scratch2, scratch3,
                                           name, miss);
     ASSERT(holder_reg.is(receiver) || holder_reg.is(scratch1));
 
+    // Preserve the receiver register explicitly whenever it is different from
+    // the holder and it is needed should the interceptor return without any
+    // result. The CALLBACKS case needs the receiver to be passed into C++ code,
+    // the FIELD case might cause a miss during the prototype check.
+    bool must_perfrom_prototype_check = *interceptor_holder != lookup->holder();
+    bool must_preserve_receiver_reg = !receiver.is(holder_reg) &&
+        (lookup->type() == CALLBACKS || must_perfrom_prototype_check);
+
     // Save necessary data before invoking an interceptor.
     // Requires a frame to make GC aware of pushed pointers.
     {
       FrameScope frame_scope(masm(), StackFrame::INTERNAL);
-      if (lookup->type() == CALLBACKS && !receiver.is(holder_reg)) {
-        // CALLBACKS case needs a receiver to be passed into C++ callback.
+      if (must_preserve_receiver_reg) {
         __ Push(receiver, holder_reg, name_reg);
       } else {
         __ Push(holder_reg, name_reg);
       }
       // Invoke an interceptor.  Note: map checks from receiver to
       // interceptor's holder has been compiled before (see a caller
       // of this method).
       CompileCallLoadPropertyWithInterceptor(masm(),
                                              receiver,
                                              holder_reg,
                                              name_reg,
                                              interceptor_holder);
       // Check if interceptor provided a value for property.  If it's
       // the case, return immediately.
       Label interceptor_failed;
       __ LoadRoot(scratch1, Heap::kNoInterceptorResultSentinelRootIndex);
       __ Branch(&interceptor_failed, eq, v0, Operand(scratch1));
       frame_scope.GenerateLeaveFrame();
       __ Ret();
 
       __ bind(&interceptor_failed);
       __ pop(name_reg);
       __ pop(holder_reg);
-      if (lookup->type() == CALLBACKS && !receiver.is(holder_reg)) {
+      if (must_preserve_receiver_reg) {
         __ pop(receiver);
       }
       // Leave the internal frame.
     }
     // Check that the maps from interceptor's holder to lookup's holder
     // haven't changed.  And load lookup's holder into |holder| register.
-    if (*interceptor_holder != lookup->holder()) {
+    if (must_perfrom_prototype_check) {
       holder_reg = CheckPrototypes(interceptor_holder,
                                    holder_reg,
                                    Handle<JSObject>(lookup->holder()),
                                    scratch1,
                                    scratch2,
                                    scratch3,
                                    name,
                                    miss);
     }
 
@@ skipping 3218 matching lines @@
     __ Jump(ic_slow, RelocInfo::CODE_TARGET);
   }
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS