Re: [PATCH] PR rtl-optimization/126521: Don't generate ABS in RTL ifcvt with NaNs.

[Richard Biener]

On Mon, Oct 5, 2026 at 5:07 PM Roger Sayle <ro...@nextmovesoftware.com> wrote:
>
>
> This patch addresses PR rtl-optimization/126521 where ifcvt transforms
> x < 0 ? -x : x (and x < 0 ? x : -x) into ABS (and NABS respectively).
> Unfortunately, these transformations are unsafe in the presence of NaNs.
> The simple fix is a one-line change to noce_try_abs.
>
> This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> and make -k check, both with and without --target_board=unix{-m32}
> with no new failures.  Ok for mainline?

OK.

>
> 2026-10-05  Roger Sayle  <ro...@nextmovesoftware.com>
>
> gcc/ChangeLog
>         PR rtl-optimization/126521
>         * ifcvt.c (noce_try_abs): These conversions are unsafe in the
>         presence of NaNs.
>
> gcc/testsuite/ChangeLog
>         PR rtl-optimization/126521
>         * gcc.target/i386/pr126521.c: New test case.
>
>
> Thanks in advance,
> Roger
> --
>