[PULL 03/13] tcg/optimize: Do use affected bits

Richard Henderson posted 13 patches 4 weeks, 1 day ago
Maintainers: Laurent Vivier <laurent@vivier.eu>, Paolo Bonzini <pbonzini@redhat.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Richard Henderson <richard.henderson@linaro.org>, Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <Alistair.Francis@wdc.com>, "Alex Bennée" <alex.bennee@linaro.org>
[PULL 03/13] tcg/optimize: Do use affected bits
Posted by Richard Henderson 4 weeks, 1 day ago
From: Paolo Bonzini <pbonzini@redhat.com>

We inadvertently disabled affected bits optimizations on operations
that use fold_masks_zosa.  These happen relatively often in x86 code
for extract/sextract; for example given the following:

   mov %esi, %ebp
   xor $0x1, %ebp

the optimizer is able to simplify the "extract_i64 rbp,tmp0,$0x0,$0x20"
produced by the second instruction to a move.

Cc: qemu-stable@nongnu.org
Fixes: 932522a9ddc ("tcg/optimize: Fold and to extract during optimize")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20251223163720.985578-1-pbonzini@redhat.com>
---
 tcg/optimize.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tcg/optimize.c b/tcg/optimize.c
index db1d89396b..5ae26e4a10 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1103,7 +1103,7 @@ static bool fold_masks_zosa_int(OptContext *ctx, TCGOp *op,
 static bool fold_masks_zosa(OptContext *ctx, TCGOp *op, uint64_t z_mask,
                             uint64_t o_mask, int64_t s_mask, uint64_t a_mask)
 {
-    fold_masks_zosa_int(ctx, op, z_mask, o_mask, s_mask, -1);
+    fold_masks_zosa_int(ctx, op, z_mask, o_mask, s_mask, a_mask);
     return true;
 }
 
-- 
2.43.0