On Thu, 30 Oct 2025, Artemiy Volkov wrote:
> The pattern introduced in r16-4682-g5eafa8d16be873 couldn't handle
> conversion from <unnamed-unsigned:1> to unsigned char, which ended up
> causing a gimple checking failure reported in PR122478. This patch fixes
> the pattern by prohibiting widening integral conversions in addition to
> the narrowing ones, or equivalently, requiring that the converted-to and
> converted-from types of the VCE both have precision equal to their size.
> Since type_has_mode_precision_p () does not apply to vector types, filter
> them out by adding a !INTEGRAL_TYPE_P () check on TREE_TYPE (@0).
>
> Bootstrapped and regtested on aarch64 and x86_64, regtested on i386 and
> riscv64, one GIMPLE test added.
OK.
> PR tree-optimization/122478
>
> gcc/ChangeLog:
>
> * match.pd: Fix the view_convert (BIT_FIELD_REF) pattern.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/pr122478.c: New test.
> ---
> gcc/match.pd | 6 ++++--
> gcc/testsuite/gcc.dg/tree-ssa/pr122478.c | 17 +++++++++++++++++
> 2 files changed, 21 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr122478.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 00493d6ad99..b65adece8dc 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -5658,10 +5658,12 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>
> /* Squash view_converts of BFRs if no precision is lost. */
> (simplify
> - (view_convert (BIT_FIELD_REF @1 @2 @3))
> + (view_convert (BIT_FIELD_REF@0 @1 @2 @3))
> (if (is_gimple_reg_type (type)
> && (!INTEGRAL_TYPE_P (type)
> - || type_has_mode_precision_p (type)))
> + || !INTEGRAL_TYPE_P (TREE_TYPE (@0))
> + || (type_has_mode_precision_p (type)
> + && type_has_mode_precision_p (TREE_TYPE (@0)))))
> (BIT_FIELD_REF:type @1 @2 @3)))
>
> /* For integral conversions with the same precision or pointer
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr122478.c
> b/gcc/testsuite/gcc.dg/tree-ssa/pr122478.c
> new file mode 100644
> index 00000000000..bc63f71274a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr122478.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +/* { dg-additional-options "-fgimple" } */
> +
> +unsigned char __GIMPLE (ssa)
> +foo (unsigned short mask__701)
> +{
> + _Bool _19;
> + unsigned char _180;
> +
> +__BB(2):
> + _19 = __BIT_FIELD_REF <_Bool> (mask__701, 1, 12);
> + _180 = __VIEW_CONVERT<unsigned char>(_19);
> + return _180;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "VIEW_CONVERT_EXPR" "optimized" 1 } } */
>
--
Richard Biener <[email protected]>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
