[arm64] Use exclusive instructions in exchange

src/arm64/decoder-arm64-inl.h

Index: src/arm64/decoder-arm64-inl.h
diff --git a/src/arm64/decoder-arm64-inl.h b/src/arm64/decoder-arm64-inl.h
index 2405f8783000751dbc5f030772d36ff7486bfe6f..5873626379fa78615075f1f8aa22404a62929919 100644
--- a/src/arm64/decoder-arm64-inl.h
+++ b/src/arm64/decoder-arm64-inl.h
@@ -213,6 +213,11 @@ void Decoder<V>::DecodeLoadStore(Instruction* instr) {
          (instr->Bits(27, 24) == 0xC) ||
          (instr->Bits(27, 24) == 0xD) );
 
+  if ((instr->Bit(28) == 0) && (instr->Bit(29) == 0) && (instr->Bit(26) == 1)) {

[binji, 2017/03/15 22:17:35]

Not necessary to check for instr->Bit(24) here?

+    DecodeAdvSIMDLoadStore(instr);
+    return;
+  }
+
   if (instr->Bit(24) == 0) {
     if (instr->Bit(28) == 0) {
       if (instr->Bit(29) == 0) {
@@ -221,13 +226,10 @@ void Decoder<V>::DecodeLoadStore(Instruction* instr) {
               instr->Mask(0xA00000) == 0xA00000) {
             V::VisitUnallocated(instr);
           } else if (instr->Mask(0x808000) == 0) {
-            // Load/Store exclusive without acquire/release are unimplemented.
-            V::VisitUnimplemented(instr);
+            V::VisitLoadStoreExclusive(instr);
           } else {
             V::VisitLoadStoreAcquireRelease(instr);
           }
-        } else {
-          DecodeAdvSIMDLoadStore(instr);
         }
       } else {
         if ((instr->Bits(31, 30) == 0x3) ||