i386: Move vzeroupper pass from after reload pass to after postreload_cse [PR112760]

Regardless of the outcome of the REG_UNUSED discussions, I think
it is a good idea to move the vzeroupper pass one pass later.
As can be seen in the multiple PRs and as postreload.cc documents,
reload/LRA is known to create dead statements quite often, which
is the reason why we have postreload_cse pass at all.
Doing vzeroupper pass before such cleanup means the pass including
df_analyze for it needs to process more instructions than needed
and because mode switching adds note problem, also higher chance of
having stale REG_UNUSED notes.
And, I really don't see why vzeroupper can't wait until those cleanups
are done.

2023-12-06  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/112760
	* config/i386/i386-passes.def (pass_insert_vzeroupper): Insert
	after pass_postreload_cse rather than pass_reload.
	* config/i386/i386-features.cc (rest_of_handle_insert_vzeroupper):
	Adjust comment for it.

	* gcc.dg/pr112760.c: New test.

0 files changed, 0 insertions, 0 deletions