REXB optimization cannot be done at this level

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4420 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/tcg/x86_64/tcg-target.c b/tcg/x86_64/tcg-target.c
index 94a767a..f11bc66 100644
--- a/tcg/x86_64/tcg-target.c
+++ b/tcg/x86_64/tcg-target.c
@@ -235,7 +235,7 @@
     int rex;
     rex = ((opc >> 6) & 0x8) | ((r >> 1) & 0x4) | 
         ((x >> 2) & 2) | ((rm >> 3) & 1);
-    if (rex || ((opc & P_REXB) && r >= 4)) {
+    if (rex || (opc & P_REXB)) {
         tcg_out8(s, rex | 0x40);
     }
     if (opc & P_EXT)