BR 3392279: Fix duplicated REX prefixes

The fix for BR 3392278:

aa29b1d93f5a assemble.c: Don't drop rex prefix from instruction itself

... would cause multiple REX prefixes to be emitted for some
instructions.  Create a new flag to indicate that REX has already been
emitted, which can be cleared for each instance of an instruction.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/assemble.c b/assemble.c
index e9cd70f..ff3cea7 100644
--- a/assemble.c
+++ b/assemble.c
@@ -1,6 +1,6 @@
 /* ----------------------------------------------------------------------- *
  *
- *   Copyright 1996-2013 The NASM Authors - All Rights Reserved
+ *   Copyright 1996-2014 The NASM Authors - All Rights Reserved
  *   See the file AUTHORS included with the NASM distribution for
  *   the specific copyright holders.
  *
@@ -1365,9 +1365,12 @@ static int64_t calcsize(int32_t segment, int64_t offset, int bits,
 static inline unsigned int emit_rex(insn *ins, int32_t segment, int64_t offset, int bits)
 {
     if (bits == 64) {
-        if ((ins->rex & REX_REAL) && !(ins->rex & (REX_V | REX_EV))) {
+        if ((ins->rex & REX_REAL) &&
+            !(ins->rex & (REX_V | REX_EV)) &&
+            !ins->rex_done) {
             int rex = (ins->rex & REX_REAL) | REX_P;
             out(offset, segment, &rex, OUT_RAWDATA, 1, NO_SEG, NO_SEG);
+            ins->rex_done = true;
             return 1;
         }
     }
@@ -1389,6 +1392,8 @@ static void gencode(int32_t segment, int64_t offset, int bits,
     uint8_t opex = 0;
     enum ea_type eat = EA_SCALAR;
 
+    ins->rex_done = false;
+
     while (*codes) {
         c = *codes++;
         op1 = (c & 3) + ((opex & 1) << 2);