> Am 27.02.2025 um 21:11 schrieb Jakub Jelinek <ja...@redhat.com>:
>
> Hi!
>
> The following testcase is miscompiled since r15-7597.
> The left comparison is unsigned (x & 0x8000U) != 0) while the
> right one is signed (x >> 16) >= 0 and is actually a signbit test,
> so rsignbit is 64.
> After debugging this and reading the r15-7597 change, I believe there
> is just a pasto, the if (lsignbit) and if (rsignbit) blocks are pretty
> much identical with just the first l on all variables starting with l
> replaced with r (the only difference is that if (lsignbit) has a comment
> explaining the sign <<= 1; stuff, while it isn't repeated in the second one.
> Except the second one was using ll_unsignedp instead of rl_unsignedp
> in one spot. I think it should use the latter, the signedness of the left
> comparison doesn't affect the other one, they are basically independent
> with the exception that we check that after transformations they are both
> EQ or both NE and later on we try to merge them together.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Ok
Richard
> 2025-02-27 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/119030
> * gimple-fold.cc (fold_truth_andor_for_ifcombine): Fix a pasto,
> ll_unsignedp -> rl_unsignedp.
>
> * gcc.c-torture/execute/pr119030.c: New test.
>
> --- gcc/gimple-fold.cc.jj 2025-02-24 00:06:26.018729158 +0100
> +++ gcc/gimple-fold.cc 2025-02-27 16:27:28.843075160 +0100
> @@ -8313,7 +8313,7 @@ fold_truth_andor_for_ifcombine (enum tre
> if (rsignbit)
> {
> wide_int sign = wi::mask (rl_bitsize - 1, true, rl_bitsize);
> - if (rsignbit > rl_bitsize && ll_unsignedp)
> + if (rsignbit > rl_bitsize && rl_unsignedp)
> sign <<= 1;
> if (!rl_and_mask.get_precision ())
> rl_and_mask = sign;
> --- gcc/testsuite/gcc.c-torture/execute/pr119030.c.jj 2025-02-27
> 16:34:11.332490739 +0100
> +++ gcc/testsuite/gcc.c-torture/execute/pr119030.c 2025-02-27
> 16:33:49.778789792 +0100
> @@ -0,0 +1,26 @@
> +/* PR tree-optimization/119030 */
> +
> +static inline unsigned
> +foo (long long x)
> +{
> + return x & 0x8000;
> +}
> +
> +static inline long long
> +bar (long long x)
> +{
> + if (foo (x))
> + return -1000L;
> + else
> + return x >> 16;
> +}
> +
> +long long x = -0x20000LL;
> +
> +int
> +main ()
> +{
> + if (bar (x) >= 0)
> + __builtin_abort ();
> + return 0;
> +}
>
> Jakub
>
