Add cmpxchg and lock instructions to x64 and ia32 {dis,}assemblers

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
diff --git a/src/x64/assembler-x64.h b/src/x64/assembler-x64.h
index 77a1a57889985c52941c46cac7fb4e0ea4951f28..4df1801801458acd7359650f7368a9cb9f128875 100644
--- a/src/x64/assembler-x64.h
+++ b/src/x64/assembler-x64.h
@@ -421,11 +421,11 @@ class Operand BASE_EMBEDDED {
   friend class Assembler;
 };
 
-
 #define ASSEMBLER_INSTRUCTION_LIST(V) \
   V(add)                              \
   V(and)                              \
   V(cmp)                              \
+  V(cmpxchg)                          \
   V(dec)                              \
   V(idiv)                             \
   V(div)                              \
@@ -445,7 +445,6 @@ class Operand BASE_EMBEDDED {
   V(xchg)                             \
   V(xor)
 
-
 // Shift instructions on operands/registers with kPointerSize, kInt32Size and
 // kInt64Size.
 #define SHIFT_INSTRUCTION_LIST(V)       \
@@ -788,9 +787,15 @@ class Assembler : public AssemblerBase {
   void decb(Register dst);
   void decb(const Operand& dst);
 
+  // Lock prefix.
+  void lock();
+
   void xchgb(Register reg, const Operand& op);
   void xchgw(Register reg, const Operand& op);
 
+  void cmpxchgb(const Operand& dst, Register src);
+  void cmpxchgw(const Operand& dst, Register src);
+
   // Sign-extends rax into rdx:rax.
   void cqo();
   // Sign-extends eax into edx:eax.
@@ -2054,6 +2059,11 @@ class Assembler : public AssemblerBase {
     immediate_arithmetic_op(0x7, dst, src, size);
   }
 
+  // Compare {al,ax,eax,rax} with src.  If equal, set ZF and write dst into
+  // src. Otherwise clear ZF and write src into {al,ax,eax,rax}.  This
+  // operation is only atomic if prefixed by the lock instruction.
+  void emit_cmpxchg(const Operand& dst, Register src, int size);
+
   void emit_dec(Register dst, int size);
   void emit_dec(const Operand& dst, int size);