On Sun, Nov 21, 2021 at 3:19 PM apinski--- via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> From: Andrew Pinski <apin...@marvell.com>
>
> This PR was orignally for the missed optimization of a few isnegative which
> had been solved a long time ago (sometime before 4.4.0). I noticed there was
> one missed optimization on the gimple level. There is a match.pd pattern
> for ~a < CST but we miss that there could be a nop_convert between the the
> comparison and the bit_not. This adds the optional option cast to the current
> match.pd pattern.
>
> OK? Bootstrapped and tested on x86_64 with no regressions.
>
> PR tree-optimization/31531
>
> gcc/ChangeLog:
>
> * match.pd (~X op C): Allow for an optional nop convert.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/pr31531-1.c: New test.
> ---
> gcc/match.pd | 5 +++--
> gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c | 19 +++++++++++++++++++
> 2 files changed, 22 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 37c5be9e5f4..ca6c9eff624 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -4729,10 +4729,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (for cmp (simple_comparison)
> scmp (swapped_simple_comparison)
> (simplify
> - (cmp (bit_not@2 @0) CONSTANT_CLASS_P@1)
> + (cmp (nop_convert?:s (bit_not@2 @0)) CONSTANT_CLASS_P@1)
Any specific reason you add :s to the conversion?
OK with removing it.
Thanks,
Richard.
> (if (single_use (@2)
> && (TREE_CODE (@1) == INTEGER_CST || TREE_CODE (@1) == VECTOR_CST))
> - (scmp @0 (bit_not @1)))))
> + (with { tree type1 = TREE_TYPE (@1); }
> + (scmp (convert:type1 @0) (bit_not @1))))))
>
> (for cmp (simple_comparison)
> /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c
> new file mode 100644
> index 00000000000..c27299151eb
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c
> @@ -0,0 +1,19 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +/* PR tree-optimization/31531 */
> +
> +int f(int a)
> +{
> + int b = ~a;
> + return b<0;
> +}
> +
> +
> +int f1(unsigned a)
> +{
> + int b = ~a;
> + return b<0;
> +}
> +/* We should convert the above two functions from b <0 to ((int)a) >= 0. */
> +/* { dg-final { scan-tree-dump-times ">= 0" 2 "optimized"} } */
> +/* { dg-final { scan-tree-dump-times "~" 0 "optimized"} } */
> --
> 2.17.1
>
