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tcg/optimize: Simplify sign bit test in fold_shift

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Merge the two conditions, sign != 0 && !(z_mask & sign),
by testing ~z_mask & sign.   If sign == 0, the logical and
will produce false.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2024-12-19 19:38:54 -08:00
parent 4e9ce6a2ec
commit 4ed2ba3f4a
1 changed files with 2 additions and 3 deletions
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tcg/optimize.c
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@ -2530,7 +2530,7 @@ static bool fold_sextract(OptContext *ctx, TCGOp *op)
static bool fold_shift(OptContext *ctx, TCGOp *op) static bool fold_shift(OptContext *ctx, TCGOp *op)
{ {
uint64_t s_mask, z_mask, sign; uint64_t s_mask, z_mask;
TempOptInfo *t1, *t2; TempOptInfo *t1, *t2;
if (fold_const2(ctx, op) || if (fold_const2(ctx, op) ||
@ -2565,8 +2565,7 @@ static bool fold_shift(OptContext *ctx, TCGOp *op)
* If the sign bit is known zero, then logical right shift * If the sign bit is known zero, then logical right shift
* will not reduce the number of input sign repetitions. * will not reduce the number of input sign repetitions.
*/ */
sign = -s_mask; if (~z_mask & -s_mask) {
if (sign && !(z_mask & sign)) {
return fold_masks_s(ctx, op, s_mask); return fold_masks_s(ctx, op, s_mask);
} }
break; break;