Hi!
On Mon, Aug 31, 2020 at 11:46:07AM +0800, Kewen.Lin wrote:
> This patch is to backport the fix for PR92923 and its sequent fix for
> PR93136 to GCC-9 branch. We found the builtin functions needlessly
> using VIEW_CONVERT_EXPRs on their operands can probably cause
> remarkable performance issue especailly when they are in the hotspot.
> One typical case is
> https://github.com/antonblanchard/crc32-vpmsum/blob/master/vec_crc32.c
> With this patch, the execution time can improve 47.81%.
:-)
> btw, one thing I'm not sure about the changelog, the original patch is
> based on the rs6000-call.c refactored codes, the changelog file entries
> are not applied well for GCC9. Do I need to put one revised changelog
> as well? if so, where to put it and what's the concise writing format
> when just for different file names? Thanks in advance!
You cannot, with the current changelog scripts, afaik. You can write
a new changelog, or say it is backported, not both or a mix. In the
good old days you could say what you did on a backport that would not
apply directly.
> -/* { dg-options "-mvsx -O2" } */
> +/* Disable ipa-icf to avoid compiler to generate tail call for some function,
> + we can not get the expected assembly due the omitted function body. */
> +/* { dg-options "-mvsx -O2 -fno-ipa-icf" } */
Thanks for adding a comment! Maybe just "Disable ipa-icf to prevent
tail calls." (It is a pretty common problem in testcases; another
trick is to put asm(""); at the end of a function).
Okay for backporting. Thanks!
Segher
