On Fri, Oct 6, 2023 at 1:15 AM Andrew Pinski <pins...@gmail.com> wrote:>
> Match has a pattern which converts `vec_cond(vec_cond(a,b,0), c, d)`
> into `vec_cond(a & b, c, d)` but since in this case a is a comparison
> fold will change `a & b` back into `vec_cond(a,b,0)` which causes an
> infinite loop.
> The best way to fix this is to enable the patterns for vec_cond(*,vec_cond,*)
> only for GIMPLE so we don't get an infinite loop for fold any more.
>
> Note this is a latent bug since these patterns were added in
> r11-2577-g229752afe3156a
> and was exposed by r14-3350-g47b833a9abe1 where now able to remove a
> VIEW_CONVERT_EXPR.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
OK (also for branches if you like)
Richard.
> PR middle-end/111699
>
> gcc/ChangeLog:
>
> * match.pd ((c ? a : b) op d, (c ? a : b) op (c ? d : e),
> (v ? w : 0) ? a : b, c1 ? c2 ? a : b : b): Enable only for GIMPLE.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.c-torture/compile/pr111699-1.c: New test.
> ---
> gcc/match.pd | 5 +++++
> gcc/testsuite/gcc.c-torture/compile/pr111699-1.c | 7 +++++++
> 2 files changed, 12 insertions(+)
> create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr111699-1.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 4bdd83e6e06..31bfd8b6b68 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -5045,6 +5045,10 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> /* (v ? w : 0) ? a : b is just (v & w) ? a : b
> Currently disabled after pass lvec because ARM understands
> VEC_COND_EXPR<v==w,-1,0> but not a plain v==w fed to BIT_IOR_EXPR. */
> +#if GIMPLE
> +/* These can only be done in gimple as fold likes to convert:
> + (CMP) & N into (CMP) ? N : 0
> + and we try to match the same pattern again and again. */
> (simplify
> (vec_cond (vec_cond:s @0 @3 integer_zerop) @1 @2)
> (if (optimize_vectors_before_lowering_p () && types_match (@0, @3))
> @@ -5079,6 +5083,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (vec_cond @0 @3 (vec_cond:s @1 @2 @3))
> (if (optimize_vectors_before_lowering_p () && types_match (@0, @1))
> (vec_cond (bit_and (bit_not @0) @1) @2 @3)))
> +#endif
>
> /* Canonicalize mask ? { 0, ... } : { -1, ...} to ~mask if the mask
> types are compatible. */
> diff --git a/gcc/testsuite/gcc.c-torture/compile/pr111699-1.c
> b/gcc/testsuite/gcc.c-torture/compile/pr111699-1.c
> new file mode 100644
> index 00000000000..87b127ed199
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/compile/pr111699-1.c
> @@ -0,0 +1,7 @@
> +typedef unsigned char __attribute__((__vector_size__ (8))) V;
> +
> +void
> +foo (V *v)
> +{
> + *v = (V) 0x107B9A7FF >= (*v <= 0);
> +}
> --
> 2.39.3
>
