MIPS: Fixing illegal use of at register

src/mips/lithium-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.7
 // 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 4175 matching lines @@
         break;
     }
   }
 }
 
 
 void LCodeGen::DoStoreKeyedFixedDoubleArray(LStoreKeyed* instr) {
   DoubleRegister value = ToDoubleRegister(instr->value());
   Register elements = ToRegister(instr->elements());
   Register scratch = scratch0();
+  Register scratch_1 = scratch1();
   DoubleRegister double_scratch = double_scratch0();
   bool key_is_constant = instr->key()->IsConstantOperand();
   int base_offset = instr->base_offset();
   Label not_nan, done;
 
   // Calculate the effective address of the slot in the array to store the
   // double value.
   int element_size_shift = ElementsKindToShiftSize(FAST_DOUBLE_ELEMENTS);
   if (key_is_constant) {
     int constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
@@ skipping 11 matching lines @@
   }
 
   if (instr->NeedsCanonicalization()) {
     Label is_nan;
     // Check for NaN. All NaNs must be canonicalized.
     __ BranchF(NULL, &is_nan, eq, value, value);
     __ Branch(&not_nan);
 
     // Only load canonical NaN if the comparison above set the overflow.
     __ bind(&is_nan);
-    __ LoadRoot(at, Heap::kNanValueRootIndex);
-    __ ldc1(double_scratch, FieldMemOperand(at, HeapNumber::kValueOffset));
+    __ LoadRoot(scratch_1, Heap::kNanValueRootIndex);
+    __ ldc1(double_scratch,
+            FieldMemOperand(scratch_1, HeapNumber::kValueOffset));
     __ sdc1(double_scratch, MemOperand(scratch, 0));
     __ Branch(&done);
   }
 
   __ bind(&not_nan);
   __ sdc1(value, MemOperand(scratch, 0));
   __ bind(&done);
 }
 
 
@@ skipping 1690 matching lines @@
   __ Push(at, ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8