Re: [PATCH 4/8] Modify test, to prevent the next patch breaking it

[Richard Biener <richard.guenther@gmail.com>]

On Fri, Nov 11, 2022 at 7:48 PM Andrew Carlotti via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> The upcoming c[lt]z idiom recognition patch eliminates the need for a
> brute force computation of the iteration count of these loops. The test
> is intended to verify that ivcanon can determine the loop count when the
> condition is given by a chain of constant computations.
>
> We replace the constant operations with a more complicated chain that should
> resist future idiom recognition.

OK.

> gcc/testsuite/ChangeLog:
>
>         * gcc.dg/pr77975.c: Make tests more robust.
>
>
> --
>
>
> diff --git a/gcc/testsuite/gcc.dg/pr77975.c b/gcc/testsuite/gcc.dg/pr77975.c
> index 148cebdded964da7fce148abdf2a430c55650513..a187ce2b50c2821841e71b5b6cb243a37a66fb57 100644
> --- a/gcc/testsuite/gcc.dg/pr77975.c
> +++ b/gcc/testsuite/gcc.dg/pr77975.c
> @@ -7,10 +7,11 @@
>  unsigned int
>  foo (unsigned int *b)
>  {
> -  unsigned int a = 3;
> +  unsigned int a = 8;
>    while (a)
>      {
> -      a >>= 1;
> +      a += 5;
> +      a &= 44;
>        *b += a;
>      }
>    return a;
> @@ -21,10 +22,11 @@ foo (unsigned int *b)
>  unsigned int
>  bar (unsigned int *b)
>  {
> -  unsigned int a = 7;
> +  unsigned int a = 3;
>    while (a)
>      {
> -      a >>= 1;
> +      a += 5;
> +      a &= 44;
>        *b += a;
>      }
>    return a;