MIPS64: r6 compact branch optimization.

src/mips64/assembler-mips64-inl.h

Index: src/mips64/assembler-mips64-inl.h
diff --git a/src/mips64/assembler-mips64-inl.h b/src/mips64/assembler-mips64-inl.h
index a824ee7fc13c7d38a63a40dd079319c960498e9b..a6e0298763819cd077949f75833bce9d08d5cf33 100644
--- a/src/mips64/assembler-mips64-inl.h
+++ b/src/mips64/assembler-mips64-inl.h
@@ -438,12 +438,24 @@ void Assembler::CheckTrampolinePoolQuick(int extra_instructions) {
 }
 
 
-void Assembler::emit(Instr x) {
+void Assembler::emit(Instr x, CompactBranchType is_compact_branch) {
   if (!is_buffer_growth_blocked()) {
     CheckBuffer();
   }
+  if (IsPrevInstrCompactBranch()) {
+    if (Instruction::IsForbiddenAfterBranchInstr(x)) {
+      // Nop instruction to preceed a CTI in forbidden slot:
+      Instr nop = SPECIAL | SLL;
+      *reinterpret_cast<Instr*>(pc_) = nop;
+      pc_ += kInstrSize;
+    }
+    ClearCompactBranchState();
+  }
   *reinterpret_cast<Instr*>(pc_) = x;
   pc_ += kInstrSize;
+  if (is_compact_branch == CompactBranchType::COMPACT_BRANCH) {
+    EmittedCompactBranchInstruction();
+  }
   CheckTrampolinePoolQuick();
 }
 
@@ -452,6 +464,14 @@ void Assembler::emit(uint64_t x) {
   if (!is_buffer_growth_blocked()) {
     CheckBuffer();
   }
+  if (IsPrevInstrCompactBranch()) {
+    // Nop instruction to preceed a CTI in forbidden slot:
+    Instr nop = SPECIAL | SLL;
+    *reinterpret_cast<Instr*>(pc_) = nop;
+    pc_ += kInstrSize;
+
+    ClearCompactBranchState();
+  }
   *reinterpret_cast<uint64_t*>(pc_) = x;
   pc_ += kInstrSize * 2;
   CheckTrampolinePoolQuick();