MIPS: r6 compact branch optimization.

src/mips/simulator-mips.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 297 matching lines @@
   // Called from DecodeTypeRegisterCOP1.
   void DecodeTypeRegisterSRsType();
 
   void DecodeTypeRegisterDRsType();
 
   void DecodeTypeRegisterWRsType();
 
   void DecodeTypeRegisterLRsType();
 
   Instruction* currentInstr_;
+
   inline Instruction* get_instr() const { return currentInstr_; }
   inline void set_instr(Instruction* instr) { currentInstr_ = instr; }
 
   inline int32_t rs_reg() const { return currentInstr_->RsValue(); }
   inline int32_t rs() const { return get_register(rs_reg()); }
   inline uint32_t rs_u() const {
     return static_cast<uint32_t>(get_register(rs_reg()));
   }
   inline int32_t rt_reg() const { return currentInstr_->RtValue(); }
   inline int32_t rt() const { return get_register(rt_reg()); }
@@ skipping 11 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(int32_t current_pc) {
+    Instruction* branch_delay_instr =

[paul.l..., 2015/10/15 01:51:24]

nit: Improper use of 'delay' in name: this should be instr_after_branch or
instr_aftter_compact_branch, or inst_after_cb.

[balazs.kilvady, 2015/10/30 21:11:15]

Done.

+        reinterpret_cast<Instruction*>(current_pc + Instruction::kInstrSize);
+    if (branch_delay_instr->IsForbiddenInBranchDelay()) {
+      V8_Fatal(__FILE__, __LINE__,
+               "Error: Unexpected instruction 0x%08x immediately after a "
+               "compact branch instruction.",
+               *reinterpret_cast<uint32_t*>(branch_delay_instr));
+    }
+  }
+
   // Stop helper functions.
   bool IsWatchpoint(uint32_t code);
   void PrintWatchpoint(uint32_t code);
   void HandleStop(uint32_t code, Instruction* instr);
   bool IsStopInstruction(Instruction* instr);
   bool IsEnabledStop(uint32_t code);
   void EnableStop(uint32_t code);
   void DisableStop(uint32_t code);
   void IncreaseStopCounter(uint32_t code);
   void PrintStopInfo(uint32_t code);
@@ skipping 120 matching lines @@
   static inline void UnregisterCTryCatch() {
     Simulator::current(Isolate::Current())->PopAddress();
   }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // !defined(USE_SIMULATOR)
 #endif  // V8_MIPS_SIMULATOR_MIPS_H_