MIPS: Fixing illegal use of at register

src/mips64/assembler-mips64.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 2360 matching lines @@
   if (is_int16(src.offset_)) {
     GenInstrImmediate(LWC1, src.rm(), fd, src.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
     LoadRegPlusOffsetToAt(src);
     GenInstrImmediate(LWC1, at, fd, 0);
   }
 }
 
 
 void Assembler::ldc1(FPURegister fd, const MemOperand& src) {
+  DCHECK(!src.rm().is(at));
   if (is_int16(src.offset_)) {
     GenInstrImmediate(LDC1, src.rm(), fd, src.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
     LoadRegPlusOffsetToAt(src);
     GenInstrImmediate(LDC1, at, fd, 0);
   }
 }
 
 
 void Assembler::swc1(FPURegister fd, const MemOperand& src) {
   if (is_int16(src.offset_)) {
     GenInstrImmediate(SWC1, src.rm(), fd, src.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
     LoadRegPlusOffsetToAt(src);
     GenInstrImmediate(SWC1, at, fd, 0);
   }
 }
 
 
 void Assembler::sdc1(FPURegister fd, const MemOperand& src) {
+  DCHECK(!src.rm().is(at));
   if (is_int16(src.offset_)) {
     GenInstrImmediate(SDC1, src.rm(), fd, src.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
     LoadRegPlusOffsetToAt(src);
     GenInstrImmediate(SDC1, at, fd, 0);
   }
 }
 
 
 void Assembler::mtc1(Register rt, FPURegister fs) {
@@ skipping 863 matching lines @@
   if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
     CpuFeatures::FlushICache(pc, 4 * Assembler::kInstrSize);
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS64