Re: [PATCH 2/2] configure: Check -falign-jumps=1 -falign-functions=1 beside -falign-loops=1

[Daniel Kiper]

On Mon, Aug 23, 2021 at 11:18:38PM -0700, Fangrui Song wrote:
> Clang does not support -falign-jumps and only recently gained support
> for -falign-loops. Test all the alignment options to avoid passing
> unrecognized options to Clang:
>
>     clang-14: error: optimization flag '-falign-jumps=1' is not supported 
> [-Werror,-Wignored-optimization-argument]
>
> When compiled with older Clang, the alignment options are not added, so
> just avoid the complexity for each option.
>
> Signed-off-by: Fangrui Song <maskray@google.com>
> ---
>  configure.ac | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index 9a12151bd..8625e6776 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -798,8 +798,9 @@ fi
>
>  # Force no alignment to save space on i386.
>  if test "x$target_cpu" = xi386; then
> -  AC_CACHE_CHECK([whether -falign-loops works], [grub_cv_cc_falign_loop], [
> -    CFLAGS="$TARGET_CFLAGS -falign-loops=1 -Werror"
> +  AC_CACHE_CHECK([whether -falign-jumps=1 -falign-loops=1 
> -falign-functions=1 works],
> +    [grub_cv_cc_falign_loop], [
> +    CFLAGS="$TARGET_CFLAGS -falign-jumps=1 -falign-loops=1 
> -falign-functions=1 -Werror"

I would prefer if you add a separate check for every -falign-* option.

Daniel