From: Richard Henderson <richard.henderson@linaro.org>
Date: Fri, 20 Dec 2024 03:38:54 +0000 (-0800)
Subject: tcg/optimize: Simplify sign bit test in fold_shift
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=4ed2ba3f4abe6b3c03a905d44cdd18b3a3c1ce33;p=qemu.git

tcg/optimize: Simplify sign bit test in fold_shift

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>
---

diff --git a/tcg/optimize.c b/tcg/optimize.c
index b70e9bdaf5..26790f7c27 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -2530,7 +2530,7 @@ static bool fold_sextract(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;
 
     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
          * will not reduce the number of input sign repetitions.
          */
-        sign = -s_mask;
-        if (sign && !(z_mask & sign)) {
+        if (~z_mask & -s_mask) {
             return fold_masks_s(ctx, op, s_mask);
         }
         break;