gas/

[deliverable/binutils-gdb.git] / gas / config / tc-i386.c

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 694618f06c0241c7d1fb51a36e83b641e3cae668..4a469088ce639693c4c6e656f4a5c501028d71bd 100644 (file)
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -2615,7 +2615,15 @@ process_suffix (void)
       if (i.suffix == QWORD_MNEM_SUFFIX
          && flag_code == CODE_64BIT
          && (i.tm.opcode_modifier & NoRex64) == 0)
-       i.rex |= REX_MODE64;
+       {
+         /* Special case for xchg %rax,%rax.  It is NOP and doesn't
+            need rex64.  */
+         if (i.operands != 2
+             || i.types [0] != (Acc | Reg64)
+             || i.types [1] != (Acc | Reg64)
+             || strcmp (i.tm.name, "xchg") != 0)
+         i.rex |= REX_MODE64;
+       }
 
       /* Size floating point instruction.  */
       if (i.suffix == LONG_MNEM_SUFFIX)