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tcg/i386: Optimize setcond of TST{EQ,NE} with 0xffffffff

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This may be treated as a 32-bit EQ/NE comparison against 0,
which is in turn treated as a LTU/GEU comparison against 1.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2024-03-26 14:48:36 -10:00
parent 2623ca6ac1
commit 19517b8397
1 changed files with 15 additions and 2 deletions
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17
tcg/i386/tcg-target.c.inc
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@ -1658,6 +1658,7 @@ static void tcg_out_setcond(TCGContext *s, int rexw, TCGCond cond,
TCGArg dest, TCGArg arg1, TCGArg arg2,
int const_arg2, bool neg)
{
int cmp_rexw = rexw;
bool inv = false;
bool cleared;
int jcc;
@ -1674,6 +1675,18 @@ static void tcg_out_setcond(TCGContext *s, int rexw, TCGCond cond,
}
break;
case TCG_COND_TSTNE:
inv = true;
/* fall through */
case TCG_COND_TSTEQ:
/* If arg2 is -1, convert to LTU/GEU vs 1. */
if (const_arg2 && arg2 == 0xffffffffu) {
arg2 = 1;
cmp_rexw = 0;
goto do_ltu;
}
break;
case TCG_COND_LEU:
inv = true;
/* fall through */
@ -1697,7 +1710,7 @@ static void tcg_out_setcond(TCGContext *s, int rexw, TCGCond cond,
* We can then use NEG or INC to produce the desired result.
* This is always smaller than the SETCC expansion.
*/
tcg_out_cmp(s, TCG_COND_LTU, arg1, arg2, const_arg2, rexw);
tcg_out_cmp(s, TCG_COND_LTU, arg1, arg2, const_arg2, cmp_rexw);
/* X - X - C = -C = (C ? -1 : 0) */
tgen_arithr(s, ARITH_SBB + (neg ? rexw : 0), dest, dest);
@ -1744,7 +1757,7 @@ static void tcg_out_setcond(TCGContext *s, int rexw, TCGCond cond,
cleared = true;
}
jcc = tcg_out_cmp(s, cond, arg1, arg2, const_arg2, rexw);
jcc = tcg_out_cmp(s, cond, arg1, arg2, const_arg2, cmp_rexw);
tcg_out_modrm(s, OPC_SETCC | jcc, 0, dest);
if (!cleared) {