MIPS64: r6 compact branch optimization.

src/mips64/simulator-mips64.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 
 // Declares a Simulator for MIPS instructions if we are not generating a native
 // MIPS binary. This Simulator allows us to run and debug MIPS code generation
 // on regular desktop machines.
 // V8 calls into generated code by "calling" the CALL_GENERATED_CODE macro,
 // which will start execution in the Simulator or forwards to the real entry
@@ skipping 374 matching lines @@
     set_register(rd_reg, alu_out);
     TraceRegWr(alu_out);
   }
 
   void DecodeTypeImmediate(Instruction* instr);
   void DecodeTypeJump(Instruction* instr);
 
   // Used for breakpoints and traps.
   void SoftwareInterrupt(Instruction* instr);
 
+  // Compact branch guard.
+  void CheckForbiddenSlot(int64_t current_pc) {
+    Instruction* instr_after_compact_branch =
+        reinterpret_cast<Instruction*>(current_pc + Instruction::kInstrSize);
+    if (instr_after_compact_branch->IsForbiddenAfterBranch()) {
+      V8_Fatal(__FILE__, __LINE__,
+               "Error: Unexpected instruction 0x%08x immediately after a "
+               "compact branch instruction.",
+               *reinterpret_cast<uint32_t*>(instr_after_compact_branch));
+    }
+  }
+
   // Stop helper functions.
   bool IsWatchpoint(uint64_t code);
   void PrintWatchpoint(uint64_t code);
   void HandleStop(uint64_t code, Instruction* instr);
   bool IsStopInstruction(Instruction* instr);
   bool IsEnabledStop(uint64_t code);
   void EnableStop(uint64_t code);
   void DisableStop(uint64_t code);
   void IncreaseStopCounter(uint64_t code);
   void PrintStopInfo(uint64_t code);
 
 
   // Executes one instruction.
   void InstructionDecode(Instruction* instr);
   // Execute one instruction placed in a branch delay slot.
   void BranchDelayInstructionDecode(Instruction* instr) {
     if (instr->InstructionBits() == nopInstr) {
       // Short-cut generic nop instructions. They are always valid and they
       // never change the simulator state.
       return;
     }
 
-    if (instr->IsForbiddenInBranchDelay()) {
+    if (instr->IsForbiddenAfterBranch()) {
       V8_Fatal(__FILE__, __LINE__,
                "Eror:Unexpected %i opcode in a branch delay slot.",
                instr->OpcodeValue());
     }
     InstructionDecode(instr);
     SNPrintF(trace_buf_, " ");
   }
 
   // ICache.
   static void CheckICache(v8::internal::HashMap* i_cache, Instruction* instr);
@@ skipping 110 matching lines @@
   static inline void UnregisterCTryCatch(Isolate* isolate) {
     Simulator::current(isolate)->PopAddress();
   }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // !defined(USE_SIMULATOR)
 #endif  // V8_MIPS_SIMULATOR_MIPS_H_