I forgot to commit the changes done as response to Richards review
before committing.
Will push after bootstrap.
2021-11-05 Richard Biener <rguent...@suse.de>
* tree-vect-loop.c (vect_analyze_loop): Remove obsolete
comment and expand on another one. Combine nested if.
---
gcc/tree-vect-loop.c | 48 +++++++++-----------------------------------
1 file changed, 10 insertions(+), 38 deletions(-)
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index abf87f99d6d..b56b7a4a386 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -2998,35 +2998,6 @@ vect_analyze_loop (class loop *loop, vec_info_shared
*shared)
return opt_loop_vec_info::propagate_failure (res);
}
- /* When pick_lowest_cost_p is true, we should in principle iterate
- over all the loop_vec_infos that LOOP_VINFO could replace and
- try to vectorize LOOP_VINFO under the same conditions.
- E.g. when trying to replace an epilogue loop, we should vectorize
- LOOP_VINFO as an epilogue loop with the same VF limit. When trying
- to replace the main loop, we should vectorize LOOP_VINFO as a main
- loop too.
-
- However, autovectorize_vector_modes is usually sorted as follows:
-
- - Modes that naturally produce lower VFs usually follow modes that
- naturally produce higher VFs.
-
- - When modes naturally produce the same VF, maskable modes
- usually follow unmaskable ones, so that the maskable mode
- can be used to vectorize the epilogue of the unmaskable mode.
-
- This order is preferred because it leads to the maximum
- epilogue vectorization opportunities. Targets should only use
- a different order if they want to make wide modes available while
- disparaging them relative to earlier, smaller modes. The assumption
- in that case is that the wider modes are more expensive in some
- way that isn't reflected directly in the costs.
-
- There should therefore be few interesting cases in which
- LOOP_VINFO fails when treated as an epilogue loop, succeeds when
- treated as a standalone loop, and ends up being genuinely cheaper
- than FIRST_LOOP_VINFO. */
-
auto_vector_modes vector_modes;
/* Autodetect first vector size we try. */
vector_modes.safe_push (VOIDmode);
@@ -3042,7 +3013,10 @@ vect_analyze_loop (class loop *loop, vec_info_shared
*shared)
unsigned int first_loop_next_i = 0;
unsigned HOST_WIDE_INT simdlen = loop->simdlen;
- /* First determine the main loop vectorization mode. */
+ /* First determine the main loop vectorization mode, either the first
+ one that works, starting with auto-detecting the vector mode and then
+ following the targets order of preference, or the one with the
+ lowest cost if pick_lowest_cost_p. */
while (1)
{
unsigned int loop_vinfo_i = mode_i;
@@ -3065,15 +3039,13 @@ vect_analyze_loop (class loop *loop, vec_info_shared
*shared)
first_loop_vinfo = opt_loop_vec_info::success (NULL);
simdlen = 0;
}
- else if (pick_lowest_cost_p && first_loop_vinfo)
+ else if (pick_lowest_cost_p
+ && first_loop_vinfo
+ && vect_joust_loop_vinfos (loop_vinfo, first_loop_vinfo))
{
- /* Keep trying to roll back vectorization attempts while the
- loop_vec_infos they produced were worse than this one. */
- if (vect_joust_loop_vinfos (loop_vinfo, first_loop_vinfo))
- {
- delete first_loop_vinfo;
- first_loop_vinfo = opt_loop_vec_info::success (NULL);
- }
+ /* Pick loop_vinfo over first_loop_vinfo. */
+ delete first_loop_vinfo;
+ first_loop_vinfo = opt_loop_vec_info::success (NULL);
}
if (first_loop_vinfo == NULL)
{
--
2.31.1
