Hi!
On Wed, Apr 15, 2020 at 09:37:32PM -0400, Michael Meissner wrote:
> Fix regression caused by PR target/93932 backport.
>
> When I back ported the fix for PR target/93932 to the GCC 9 branch, I put in
> an
> unintended regression when the GCC compiler is optimizing the vec_extract
> built-in function, and the vector element is in memory, and the index is
> variable. This patch masks the vector index so that it does not go out of
> bounds.
>
> 2020-04-15 Michael Meissner <meiss...@linux.ibm.com>
>
> PR target/94557
> * config/rs6000/rs6000.c (rs6000_adjust_vec_address): Fix
> regression caused by PR target/93932 backport. Mask variable
> vector extract index so it does not go beyond the vector when
> extracting a vector element from memory.
Much better, thanks!
> --- /tmp/4XFFqK_rs6000.c 2020-04-13 15:28:33.514011024 -0500
> +++ gcc/config/rs6000/rs6000.c 2020-04-13 14:24:01.296932921 -0500
> @@ -7047,18 +7047,25 @@ rs6000_adjust_vec_address (rtx scalar_re
> element_offset = GEN_INT (INTVAL (element) * scalar_size);
> else
> {
> + /* Mask the element to make sure the element number is between 0 and
> the
> + maximum number of elements - 1 so that we don't generate an address
> + outside the vector. */
Hrm, so why do you need to do this here? It is part of the semantics of
vec_extract, so shouldn't the RTL already have this masking somewhere
when we get here?
Nevertheless, the patch is okay for 9, it certainly won't hurt. Thanks!
Segher
