Remove scratch register requirement from LoadInstanceDescriptors on arm and mips.

src/mips/full-codegen-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 1134 matching lines @@
   __ LoadRoot(at, Heap::kMetaMapRootIndex);
   __ Branch(&fixed_array, ne, a2, Operand(at));
 
   // We got a map in register v0. Get the enumeration cache from it.
   Label no_descriptors;
   __ bind(&use_cache);
 
   __ EnumLength(a1, v0);
   __ Branch(&no_descriptors, eq, a1, Operand(Smi::FromInt(0)));
 
-  __ LoadInstanceDescriptors(v0, a2, t0);
+  __ LoadInstanceDescriptors(v0, a2);
   __ lw(a2, FieldMemOperand(a2, DescriptorArray::kEnumCacheOffset));
   __ lw(a2, FieldMemOperand(a2, DescriptorArray::kEnumCacheBridgeCacheOffset));
 
   // Set up the four remaining stack slots.
   __ push(v0);  // Map.
   __ li(a0, Operand(Smi::FromInt(0)));
   // Push enumeration cache, enumeration cache length (as smi) and zero.
   __ Push(a2, a1, a0);
   __ jmp(&loop);
 
@@ skipping 1539 matching lines @@
 
   // Look for valueOf symbol in the descriptor array, and indicate false if
   // found. Since we omit an enumeration index check, if it is added via a
   // transition that shares its descriptor array, this is a false positive.
   Label entry, loop, done;
 
   // Skip loop if no descriptors are valid.
   __ NumberOfOwnDescriptors(a3, a1);
   __ Branch(&done, eq, a3, Operand(zero_reg));
 
-  __ LoadInstanceDescriptors(a1, t0, a2);
+  __ LoadInstanceDescriptors(a1, t0);
   // t0: descriptor array.
   // a3: valid entries in the descriptor array.
   STATIC_ASSERT(kSmiTag == 0);
   STATIC_ASSERT(kSmiTagSize == 1);
   STATIC_ASSERT(kPointerSize == 4);
   __ li(at, Operand(DescriptorArray::kDescriptorSize));
   __ Mul(a3, a3, at);
   // Calculate location of the first key name.
   __ Addu(t0, t0, Operand(DescriptorArray::kFirstOffset - kHeapObjectTag));
   // Calculate the end of the descriptor array.
@@ skipping 1842 matching lines @@
   *context_length = 0;
   return previous_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS