Ensure we do not clobber the register holding the elements backing store.

src/arm/stub-cache-arm.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 4672 matching lines @@
 
 void KeyedStoreStubCompiler::GenerateStoreFastDoubleElement(
     MacroAssembler* masm,
     bool is_js_array,
     KeyedAccessGrowMode grow_mode) {
   // ----------- S t a t e -------------
   //  -- r0    : value
   //  -- r1    : key
   //  -- r2    : receiver
   //  -- lr    : return address
-  //  -- r3    : scratch
+  //  -- r3    : scratch (elements backing store)
   //  -- r4    : scratch
   //  -- r5    : scratch
+  //  -- r6    : scratch
+  //  -- r7    : scratch
+  //  -- r9    : scratch
   // -----------------------------------
   Label miss_force_generic, transition_elements_kind, grow, slow;
   Label finish_store, check_capacity;
 
   Register value_reg = r0;
   Register key_reg = r1;
   Register receiver_reg = r2;
   Register elements_reg = r3;
   Register scratch1 = r4;
   Register scratch2 = r5;
   Register scratch3 = r6;
   Register scratch4 = r7;
+  Register scratch5 = r9;
   Register length_reg = r7;
 
   // This stub is meant to be tail-jumped to, the receiver must already
   // have been verified by the caller to not be a smi.
 
   // Check that the key is a smi or a heap number convertible to a smi.
   GenerateSmiKeyCheck(masm, key_reg, r4, r5, d1, d2, &miss_force_generic);
 
   __ ldr(elements_reg,
          FieldMemOperand(receiver_reg, JSObject::kElementsOffset));
@@ skipping 74 matching lines @@
            FieldMemOperand(elements_reg, FixedDoubleArray::kLengthOffset));
 
     __ mov(scratch1, Operand(kHoleNanLower32));
     __ mov(scratch2, Operand(kHoleNanUpper32));
     for (int i = 1; i < JSArray::kPreallocatedArrayElements; i++) {
       int offset = FixedDoubleArray::OffsetOfElementAt(i);
       __ str(scratch1, FieldMemOperand(elements_reg, offset));
       __ str(scratch2, FieldMemOperand(elements_reg, offset + kPointerSize));
     }
 
+    __ mov(scratch1, elements_reg);
     __ StoreNumberToDoubleElements(value_reg,
                                    key_reg,
                                    // All registers after this are overwritten.
-                                   elements_reg,
                                    scratch1,
                                    scratch2,
                                    scratch3,
                                    scratch4,
+                                   scratch5,
                                    &transition_elements_kind);
 
     // Install the new backing store in the JSArray.
     __ str(elements_reg,
            FieldMemOperand(receiver_reg, JSObject::kElementsOffset));
     __ RecordWriteField(receiver_reg, JSObject::kElementsOffset, elements_reg,
                         scratch1, kLRHasNotBeenSaved, kDontSaveFPRegs,
                         EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
 
     // Increment the length of the array.
@@ skipping 20 matching lines @@
     __ Jump(ic_slow, RelocInfo::CODE_TARGET);
   }
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM