MIPS: r6 compact branch optimization.

src/mips/constants-mips.cc

Index: src/mips/constants-mips.cc
diff --git a/src/mips/constants-mips.cc b/src/mips/constants-mips.cc
index ff8a79f1b2246870e4ec1e221f965c2deff05aa0..1b23ed3b5fa2a63bd800a07d042ffb075b036c6b 100644
--- a/src/mips/constants-mips.cc
+++ b/src/mips/constants-mips.cc
@@ -126,24 +126,28 @@ int FPURegisters::Number(const char* name) {
 // -----------------------------------------------------------------------------
 // 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:
@@ -154,7 +158,7 @@ bool Instruction::IsForbiddenInBranchDelay() const {
       }
       break;
     case SPECIAL:
-      switch (FunctionFieldRaw()) {
+      switch (instr & kFunctionFieldMask) {
         case JR:
         case JALR:
           return true;
@@ -169,8 +173,7 @@ bool Instruction::IsForbiddenInBranchDelay() const {
 
 
 bool Instruction::IsLinkingInstruction() const {
-  const int op = OpcodeFieldRaw();
-  switch (op) {
+  switch (OpcodeFieldRaw()) {
     case JAL:
       return true;
     case POP76: