Re: [PATCH] generic-match-head: Don't assume GENERIC folding is done only early [PR108237]

[Richard Biener via Gcc-patches]

> Am 04.01.2023 um 10:22 schrieb Jakub Jelinek <ja...@redhat.com>:
> 
> Hi!
> 
> We ICE on the following testcase, because a valid V2DImode
> != comparison is folded into an unsupported V2DImode > comparison.
> The match.pd pattern which does this looks like:
> /* Transform comparisons of the form (X & Y) CMP 0 to X CMP2 Z
>   where ~Y + 1 == pow2 and Z = ~Y.  */
> (for cst (VECTOR_CST INTEGER_CST)
> (for cmp (eq ne)
>      icmp (le gt)
>  (simplify
>   (cmp (bit_and:c@2 @0 cst@1) integer_zerop)
>    (with { tree csts = bitmask_inv_cst_vector_p (@1); }
>     (if (csts && (VECTOR_TYPE_P (TREE_TYPE (@1)) || single_use (@2)))
>      (with { auto optab = VECTOR_TYPE_P (TREE_TYPE (@1))
>                         ? optab_vector : optab_default;
>              tree utype = unsigned_type_for (TREE_TYPE (@1)); }
>       (if (target_supports_op_p (utype, icmp, optab)
>            || (optimize_vectors_before_lowering_p ()
>                && (!target_supports_op_p (type, cmp, optab)
>                    || !target_supports_op_p (type, BIT_AND_EXPR, optab))))
>        (if (TYPE_UNSIGNED (TREE_TYPE (@1)))
>         (icmp @0 { csts; })
>         (icmp (view_convert:utype @0) { csts; })))))))))
> and that optimize_vectors_before_lowering_p () guarded stuff there
> already deals with this problem, not trying to fold a supported comparison
> into a non-supported one.  The reason it doesn't work in this case is that
> it isn't GIMPLE folding which does this, but GENERIC folding done during
> forwprop4 - forward_propagate_into_comparison -> 
> forward_propagate_into_comparison_1
> -> combine_cond_expr_cond -> fold_binary_loc -> generic_simplify
> and we simply assumed that GENERIC folding happens only before
> gimplification.
> 
> The following patch fixes that by checking cfun properties instead of
> always returning true in thos cases.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Ok

Richard 

> 2023-01-04  Jakub Jelinek  <ja...@redhat.com>
> 
>    PR middle-end/108237
>    * generic-match-head.cc: Include tree-pass.h.
>    (canonicalize_math_p, optimize_vectors_before_lowering_p): Define
>    to false if cfun and cfun->curr_properties has PROP_gimple_opt_math
>    resp. PROP_gimple_lvec property set.
> 
>    * gcc.c-torture/compile/pr108237.c: New test.
> 
> --- gcc/generic-match-head.cc.jj    2023-01-02 09:32:42.954988078 +0100
> +++ gcc/generic-match-head.cc    2023-01-03 17:31:07.627941369 +0100
> @@ -40,6 +40,7 @@ along with GCC; see the file COPYING3.
> #include "tm.h"
> #include "tree-eh.h"
> #include "langhooks.h"
> +#include "tree-pass.h"
> 
> /* Routine to determine if the types T1 and T2 are effectively
>    the same for GENERIC.  If T1 or T2 is not a type, the test
> @@ -71,7 +72,7 @@ single_use (tree t ATTRIBUTE_UNUSED)
> static inline bool
> canonicalize_math_p ()
> {
> -  return true;
> +  return !cfun || (cfun->curr_properties & PROP_gimple_opt_math) == 0;
> }
> 
> /* Return true if math operations that are beneficial only after
> @@ -90,7 +91,7 @@ canonicalize_math_after_vectorization_p
> static inline bool
> optimize_vectors_before_lowering_p ()
> {
> -  return true;
> +  return !cfun || (cfun->curr_properties & PROP_gimple_lvec) == 0;
> }
> 
> /* Return true if successive divisions can be optimized.
> --- gcc/testsuite/gcc.c-torture/compile/pr108237.c.jj    2023-01-03 
> 17:35:37.411068635 +0100
> +++ gcc/testsuite/gcc.c-torture/compile/pr108237.c    2023-01-03 
> 17:35:22.490282820 +0100
> @@ -0,0 +1,14 @@
> +/* PR middle-end/108237 */
> +
> +typedef unsigned char __attribute__((__vector_size__ (1))) U;
> +typedef unsigned long long __attribute__((__vector_size__ (16))) V;
> +
> +U u;
> +V v;
> +
> +V
> +foo (void)
> +{
> +  V w = v != ((unsigned char) ((unsigned char) u == u) & v);
> +  return w;
> +}
> 
>    Jakub
>