Re: [PATCH] [PR100106] Reject unaligned subregs when strict alignment is required

[Vladimir Makarov <vmakarov@redhat.com>]

On 2022-05-05 02:52, Alexandre Oliva wrote:
>
> Regstrapped on x86_64-linux-gnu and ppc64le-linux-gnu, also tested
> targeting ppc- and ppc64-vx7r2.  Ok to install?
>
I am ok with the modified version of the patch.  It looks reasonable for 
me and I support its commit.

But I think I can not approve the patch formally as emit-rtl.cc is out 
of my jurisdiction and validate_subreg is used in many places besides RA.

Sorry, Alex, some global reviewer should do this.

> for  gcc/ChangeLog
>
> 	PR target/100106
> 	* emit-rtl.c (validate_subreg): Reject a SUBREG of a MEM that
> 	requires stricter alignment than MEM's.
>
> for  gcc/testsuite/ChangeLog
>
> 	PR target/100106
> 	* gcc.target/powerpc/pr100106-sa.c: New.
> ---
>   gcc/emit-rtl.cc                                |    3 +++
>   gcc/testsuite/gcc.target/powerpc/pr100106-sa.c |    4 ++++
>   2 files changed, 7 insertions(+)
>   create mode 100644 gcc/testsuite/gcc.target/powerpc/pr100106-sa.c
>
> diff --git a/gcc/emit-rtl.cc b/gcc/emit-rtl.cc
> index 1e02ae254d012..642e47eada0d7 100644
> --- a/gcc/emit-rtl.cc
> +++ b/gcc/emit-rtl.cc
> @@ -982,6 +982,9 @@ validate_subreg (machine_mode omode, machine_mode imode,
>   
>         return subreg_offset_representable_p (regno, imode, offset, omode);
>       }
> +  else if (reg && MEM_P (reg)
> +	   && STRICT_ALIGNMENT && MEM_ALIGN (reg) < GET_MODE_ALIGNMENT (omode))
> +    return false;
>   
>     /* The outer size must be ordered wrt the register size, otherwise
>        we wouldn't know at compile time how many registers the outer
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr100106-sa.c b/gcc/testsuite/gcc.target/powerpc/pr100106-sa.c
> new file mode 100644
> index 0000000000000..6cc29595c8b25
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr100106-sa.c
> @@ -0,0 +1,4 @@
> +/* { dg-do compile { target { ilp32 } } } */
> +/* { dg-options "-mcpu=604 -O -mstrict-align" } */
> +
> +#include "../../gcc.c-torture/compile/pr100106.c"
>
>