[Atomics] code stubs for atomic operations

src/arm/disasm-arm.cc

Index: src/arm/disasm-arm.cc
diff --git a/src/arm/disasm-arm.cc b/src/arm/disasm-arm.cc
index 66b7f4584943b3b9dc9fd3aa9749d39d5039a6a0..ecf5acc93593e18f60875e60664f46322da54a38 100644
--- a/src/arm/disasm-arm.cc
+++ b/src/arm/disasm-arm.cc
@@ -1689,6 +1689,12 @@ void Decoder::DecodeType6CoprocessorIns(Instruction* instr) {
 }
 
 
+static const char* const barrier_option_names[] = {
+    "invalid", "oshld", "oshst", "osh", "invalid", "nshld", "nshst", "nsh",
+    "invalid", "ishld", "ishst", "ish", "invalid", "ld",    "st",    "sy",
+};
+
+
 void Decoder::DecodeSpecialCondition(Instruction* instr) {
   switch (instr->SpecialValue()) {
     case 5:
@@ -1765,6 +1771,24 @@ void Decoder::DecodeSpecialCondition(Instruction* instr) {
           out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
                                       "pld [r%d, #+%d]", Rn, offset);
         }
+      } else if (instr->SpecialValue() == 0xA && instr->Bits(22, 20) == 7) {
+        int option = instr->Bits(3, 0);
+        switch (instr->Bits(7, 4)) {
+          case 4:
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "dsb %s", barrier_option_names[option]);
+            break;
+          case 5:
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "dmb %s", barrier_option_names[option]);
+            break;
+          case 6:
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "isb %s", barrier_option_names[option]);
+            break;
+          default:
+            Unknown(instr);
+        }
       } else {
         Unknown(instr);
       }