MIPS: r6 compact branch optimization.

src/mips/constants-mips.cc

 // 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.
 
 #if V8_TARGET_ARCH_MIPS
 
 #include "src/mips/constants-mips.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 108 matching lines @@
   }
 
   // No Cregister with the reguested name found.
   return kInvalidFPURegister;
 }
 
 
 // -----------------------------------------------------------------------------
 // Instructions.
 
-bool Instruction::IsForbiddenInBranchDelay() const {
-  const int op = OpcodeFieldRaw();
-  switch (op) {
+bool Instruction::IsForbiddenAfterBranchInstr(Instr instr) {
+  Opcode opcode = static_cast<Opcode>(instr & kOpcodeMask);
+  switch (opcode) {
     case J:
     case JAL:
     case BEQ:
     case BNE:
-    case BLEZ:
-    case BGTZ:
+    case BLEZ:  // POP06 bgeuc/bleuc, blezalc, bgezalc
+    case BGTZ:  // POP07 bltuc/bgtuc, bgtzalc, bltzalc
     case BEQL:
     case BNEL:
-    case BLEZL:
-    case BGTZL:
+    case BLEZL:  // POP26 bgezc, blezc, bgec/blec
+    case BGTZL:  // POP27 bgtzc, bltzc, bltc/bgtc
     case BC:
     case BALC:
+    case POP10:  // beqzalc, bovc, beqc
+    case POP30:  // bnezalc, bvnc, bnec
+    case POP66:  // beqzc, jic
+    case POP76:  // bnezc, jialc
       return true;
     case REGIMM:
-      switch (RtFieldRaw()) {
+      switch (instr & kRtFieldMask) {
         case BLTZ:
         case BGEZ:
         case BLTZAL:
         case BGEZAL:
           return true;
         default:
           return false;
       }
       break;
     case SPECIAL:
-      switch (FunctionFieldRaw()) {
+      switch (instr & kFunctionFieldMask) {
         case JR:
         case JALR:
           return true;
         default:
           return false;
       }
       break;
     default:
       return false;
   }
 }
 
 
 bool Instruction::IsLinkingInstruction() const {
-  const int op = OpcodeFieldRaw();
-  switch (op) {
+  switch (OpcodeFieldRaw()) {
     case JAL:
       return true;
     case POP76:
       if (RsFieldRawNoAssert() == JIALC)
         return true;  // JIALC
       else
         return false;  // BNEZC
     case REGIMM:
       switch (RtFieldRaw()) {
         case BGEZAL:
@@ skipping 32 matching lines @@
         return false;
     }
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS