[PATCH] malloc: obscure calloc use in tst-calloc

[H.J. Lu]

On Fri, Jan 10, 2025, 11:12 AM Sam James <sam@gentoo.org> wrote:

> Similar to a9944a52c967ce76a5894c30d0274b824df43c7a and
> f9493a15ea9cfb63a815c00c23142369ec09d8ce, we need to hide calloc use from
> the compiler to accommodate GCC's r15-6566-g804e9d55d9e54c change.
>
> First, include tst-malloc-aux.h, but then use `volatile` variables
> for size.
>
> The test passes without the tst-malloc-aux.h change but IMO we want
> it there for consistency and to avoid future problems (possibly silent).
> ---
>  malloc/tst-calloc.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/malloc/tst-calloc.c b/malloc/tst-calloc.c
> index 77a32f8052..122b2cbeaf 100644
> --- a/malloc/tst-calloc.c
> +++ b/malloc/tst-calloc.c
> @@ -23,6 +23,7 @@
>  #include <stdio.h>
>  #include <libc-diag.h>
>
> +#include "tst-malloc-aux.h"
>
>  /* Number of samples per size.  */
>  #define N 50000
> @@ -94,16 +95,19 @@ random_test (void)
>  static void
>  null_test (void)
>  {
> +  /* Obscure allocation size from the compiler.  */
> +  volatile size_t max_size = UINT_MAX;
> +  volatile size_t zero_size = 0;
>    /* If the size is 0 the result is implementation defined.  Just make
>       sure the program doesn't crash.  The result of calloc is
>       deliberately ignored, so do not warn about that.  */
>    DIAG_PUSH_NEEDS_COMMENT;
>    DIAG_IGNORE_NEEDS_COMMENT (10, "-Wunused-result");
>    calloc (0, 0);
> -  calloc (0, UINT_MAX);
> -  calloc (UINT_MAX, 0);
> -  calloc (0, ~((size_t) 0));
> -  calloc (~((size_t) 0), 0);
> +  calloc (0, max_size);
> +  calloc (max_size, 0);
> +  calloc (0, ~((size_t) zero_size));
> +  calloc (~((size_t) zero_size), 0);
>    DIAG_POP_NEEDS_COMMENT;
>  }
>
>
> base-commit: dad44389f2f96523080e3b105eee1b1ab8b19722
> prerequisite-patch-id: 6bc066b9be8e3c65fae35848708646513d151266
> --
> 2.48.0.rc2
>

LGTM.

Thanks.


>
>
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