X87: Add cmpxchg and lock instructions to x64 and ia32 {dis,}assemblers.

src/x87/assembler-x87.cc

Index: src/x87/assembler-x87.cc
diff --git a/src/x87/assembler-x87.cc b/src/x87/assembler-x87.cc
index 5cc783c86ae40b332d34fad8bdd3b63ebc635297..3716d8ecf14f62e633be0340355b20f6eeae8d49 100644
--- a/src/x87/assembler-x87.cc
+++ b/src/x87/assembler-x87.cc
@@ -601,6 +601,33 @@ void Assembler::xchg_w(Register reg, const Operand& op) {
   emit_operand(reg, op);
 }
 
+void Assembler::lock() {
+  EnsureSpace ensure_space(this);
+  EMIT(0xF0);
+}
+
+void Assembler::cmpxchg(const Operand& dst, Register src) {
+  EnsureSpace ensure_space(this);
+  EMIT(0x0F);
+  EMIT(0xB1);
+  emit_operand(src, dst);
+}
+
+void Assembler::cmpxchg_b(const Operand& dst, Register src) {
+  EnsureSpace ensure_space(this);
+  EMIT(0x0F);
+  EMIT(0xB0);
+  emit_operand(src, dst);
+}
+
+void Assembler::cmpxchg_w(const Operand& dst, Register src) {
+  EnsureSpace ensure_space(this);
+  EMIT(0x66);
+  EMIT(0x0F);
+  EMIT(0xB1);
+  emit_operand(src, dst);
+}
+
 void Assembler::adc(Register dst, int32_t imm32) {
   EnsureSpace ensure_space(this);
   emit_arith(2, Operand(dst), Immediate(imm32));