From: Paolo Bonzini <pbonzini@redhat.com>

Just like when testing against the sign bits, TEST r,r can be used when the
immediate is 0xff, 0xff00, 0xffff, 0xffffffff.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/i386/tcg-target.c.inc | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc
index 0b8c60d021..c6ba498623 100644
--- a/tcg/i386/tcg-target.c.inc
+++ b/tcg/i386/tcg-target.c.inc
@@ -1501,6 +1501,10 @@ static int tcg_out_cmp(TCGContext *s, TCGCond cond, TCGArg arg1,
             tcg_out_modrm(s, OPC_TESTB | P_REXB_R, arg1, arg1);
             return js;
         }
+        if (arg2 == 0xff) {
+            tcg_out_modrm(s, OPC_TESTB | P_REXB_R, arg1, arg1);
+            return jz;
+        }
         tcg_out_modrm(s, OPC_GRP3_Eb | P_REXB_RM, EXT3_TESTi, arg1);
         tcg_out8(s, arg2);
         return jz;
@@ -1511,11 +1515,24 @@ static int tcg_out_cmp(TCGContext *s, TCGCond cond, TCGArg arg1,
             tcg_out_modrm(s, OPC_TESTB, arg1 + 4, arg1 + 4);
             return js;
         }
+        if (arg2 == 0xff00) {
+            tcg_out_modrm(s, OPC_TESTB, arg1 + 4, arg1 + 4);
+            return jz;
+        }
         tcg_out_modrm(s, OPC_GRP3_Eb, EXT3_TESTi, arg1 + 4);
         tcg_out8(s, arg2 >> 8);
         return jz;
     }
 
+    if (arg2 == 0xffff) {
+        tcg_out_modrm(s, OPC_TESTL | P_DATA16, arg1, arg1);
+        return jz;
+    }
+    if (arg2 == 0xffffffffu) {
+        tcg_out_modrm(s, OPC_TESTL, arg1, arg1);
+        return jz;
+    }
+
     if (is_power_of_2(rexw ? arg2 : (uint32_t)arg2)) {
         int jc = (cond == TCG_COND_TSTNE ? JCC_JB : JCC_JAE);
         int sh = ctz64(arg2);
-- 
2.34.1