On Wed, Mar 13, 2024 at 3:39 PM Joe Ramsay wrote:
>
> This optimisation does not honour signed zeros, so should not be
> enabled except with -fno-signed-zeros.
>
> OK for master? I do not have commit rights for GCC, so if the patch
> is fine would someone be able to commit for me? The bug is present
> in all GCC versions from 12.1.0 onwards - is it possible to backport
> this?
>
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
>
> Thanks,
> Joe
>
> gcc/ChangeLog:
>
> * match.pd: Fix truncation pattern for -fno-signed-zeroes
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/aarch64/no_merge_trunc_signed_zero.c: New test.
> ---
> gcc/match.pd | 2 +-
> .../aarch64/no_merge_trunc_signed_zero.c | 24 +++
> 2 files changed, 25 insertions(+), 1 deletion(-)
> create mode 100644
> gcc/testsuite/gcc.target/aarch64/no_merge_trunc_signed_zero.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 9ce313323a3..45c34c810cf 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -4857,7 +4857,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> #if GIMPLE
> (simplify
> (float (fix_trunc @0))
> - (if (!flag_trapping_math
> + (if (!flag_trapping_math && !HONOR_SIGNED_ZEROS(type)
put the && to the next line and add a space before (type)
OK with that change.
Richard.
> && types_match (type, TREE_TYPE (@0))
> && direct_internal_fn_supported_p (IFN_TRUNC, type,
> OPTIMIZE_FOR_BOTH))
> diff --git a/gcc/testsuite/gcc.target/aarch64/no_merge_trunc_signed_zero.c
> b/gcc/testsuite/gcc.target/aarch64/no_merge_trunc_signed_zero.c
> new file mode 100644
> index 000..b2c93e55567
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/no_merge_trunc_signed_zero.c
> @@ -0,0 +1,24 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fno-trapping-math -fsigned-zeros" } */
> +
> +#include
> +
> +float
> +f1 (float x)
> +{
> + return (int) rintf(x);
> +}
> +
> +double
> +f2 (double x)
> +{
> + return (long) rint(x);
> +}
> +
> +/* { dg-final { scan-assembler "frintx\\ts\[0-9\]+, s\[0-9\]+" } } */
> +/* { dg-final { scan-assembler "cvtzs\\ts\[0-9\]+, s\[0-9\]+" } } */
> +/* { dg-final { scan-assembler "scvtf\\ts\[0-9\]+, s\[0-9\]+" } } */
> +/* { dg-final { scan-assembler "frintx\\td\[0-9\]+, d\[0-9\]+" } } */
> +/* { dg-final { scan-assembler "cvtzs\\td\[0-9\]+, d\[0-9\]+" } } */
> +/* { dg-final { scan-assembler "scvtf\\td\[0-9\]+, d\[0-9\]+" } } */
> +
> --
> 2.27.0
>
