[Qemu-devel] [PATCH 3/5] tcg/i386: add support for three-byte opcodes

[Aurelien Jarno <aurelien@aurel32.net>]

Add support for three-byte opcodes, starting with the 0x0f 0x38 prefix.
Use P_EXT2 as the new constant, and shift all other constants so that
P_EXT and P_EXT2 have neighbouring values.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
---
 tcg/i386/tcg-target.c |   22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c
index 753b3a1..e247829 100644
--- a/tcg/i386/tcg-target.c
+++ b/tcg/i386/tcg-target.c
@@ -240,13 +240,14 @@ static inline int tcg_target_const_match(tcg_target_long val,
 #endif
 
 #define P_EXT		0x100		/* 0x0f opcode prefix */
-#define P_DATA16	0x200		/* 0x66 opcode prefix */
+#define P_EXT2          0x200           /* 0x0f 0x38 opcode prefix */
+#define P_DATA16        0x400           /* 0x66 opcode prefix */
 #if TCG_TARGET_REG_BITS == 64
-# define P_ADDR32	0x400		/* 0x67 opcode prefix */
-# define P_REXW		0x800		/* Set REX.W = 1 */
-# define P_REXB_R	0x1000		/* REG field as byte register */
-# define P_REXB_RM	0x2000		/* R/M field as byte register */
-# define P_GS           0x4000          /* gs segment override */
+# define P_ADDR32       0x800           /* 0x67 opcode prefix */
+# define P_REXW         0x1000          /* Set REX.W = 1 */
+# define P_REXB_R       0x2000          /* REG field as byte register */
+# define P_REXB_RM      0x4000          /* R/M field as byte register */
+# define P_GS           0x8000          /* gs segment override */
 #else
 # define P_ADDR32	0
 # define P_REXW		0
@@ -401,6 +402,11 @@ static void tcg_out_opc(TCGContext *s, int opc, int r, int rm, int x)
     if (opc & P_EXT) {
         tcg_out8(s, 0x0f);
     }
+
+    if (opc & P_EXT2) {
+        tcg_out8(s, 0x0f);
+        tcg_out8(s, 0x38);
+    }
     tcg_out8(s, opc);
 }
 #else
@@ -412,6 +418,10 @@ static void tcg_out_opc(TCGContext *s, int opc)
     if (opc & P_EXT) {
         tcg_out8(s, 0x0f);
     }
+    if (opc & P_EXT2) {
+        tcg_out8(s, 0x0f);
+        tcg_out8(s, 0x38);
+    }
     tcg_out8(s, opc);
 }
 /* Discard the register arguments to tcg_out_opc early, so as not to penalize
-- 
1.7.10.4