From: Paolo Bonzini <pbonz...@redhat.com>
In the case where OR or XOR has an 8-bit immediate between 128 and 255,
we can operate on a low-byte register and shorten the output by two or
three bytes (two if a prefix byte is needed for REX.B).
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
Message-Id: <20231228120524.70239-1-pbonz...@redhat.com>
[rth: Incorporate into switch.]
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
tcg/i386/tcg-target.c.inc | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc
index 29e80af78b..d268199fc1 100644
--- a/tcg/i386/tcg-target.c.inc
+++ b/tcg/i386/tcg-target.c.inc
@@ -244,6 +244,7 @@ static bool tcg_target_const_match(int64_t val, TCGType
type, int ct, int vece)
#define P_VEXL 0x80000 /* Set VEX.L = 1 */
#define P_EVEX 0x100000 /* Requires EVEX encoding */
+#define OPC_ARITH_EbIb (0x80)
#define OPC_ARITH_EvIz (0x81)
#define OPC_ARITH_EvIb (0x83)
#define OPC_ARITH_GvEv (0x03) /* ... plus (ARITH_FOO << 3) */
@@ -1370,6 +1371,16 @@ static void tgen_arithi(TCGContext *s, int c, int r0,
return;
}
break;
+
+ case ARITH_OR:
+ case ARITH_XOR:
+ if (val >= 0x80 && val <= 0xff
+ && (r0 < 4 || TCG_TARGET_REG_BITS == 64)) {
+ tcg_out_modrm(s, OPC_ARITH_EbIb + P_REXB_RM, c, r0);
+ tcg_out8(s, val);
+ return;
+ }
+ break;
}
if (val == (int8_t)val) {
--
2.34.1
