The following hopefully addresses an observed bootstrap issue on aarch64
where maybe-uninit diagnostics occur. It also fixes bogus napkin math
from myself when I was confusing rounded up size of a single access
with rounded up size of the group accessed in a single scalar iteration.
So the following puts in a correctness check, leaving a set of peeling
for gaps as insufficient. This could be rectified by splitting the
last load into multiple ones but I'm leaving this for a followup, better
quickly fix the reported wrong-code.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
* tree-vect-stmts.cc (get_group_load_store_type): Do not
re-use poly-int remain but re-compute with non-poly values.
Verify the shortened load is good enough to be covered with
a single scalar gap iteration before accepting it.
* gcc.dg/vect/pr115385.c: Enable AVX2 if available.
---
gcc/testsuite/gcc.dg/vect/pr115385.c | 1 +
gcc/tree-vect-stmts.cc | 12 +++++++-----
2 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/vect/pr115385.c
b/gcc/testsuite/gcc.dg/vect/pr115385.c
index a18cd665d7d..baea0b2473f 100644
--- a/gcc/testsuite/gcc.dg/vect/pr115385.c
+++ b/gcc/testsuite/gcc.dg/vect/pr115385.c
@@ -1,4 +1,5 @@
/* { dg-require-effective-target mmap } */
+/* { dg-additional-options "-mavx2" { target avx2_runtime } } */
#include <sys/mman.h>
#include <stdio.h>
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index e32d44050e5..ca6052662a3 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -2148,15 +2148,17 @@ get_group_load_store_type (vec_info *vinfo,
stmt_vec_info stmt_info,
{
/* But peeling a single scalar iteration is enough if
we can use the next power-of-two sized partial
- access. */
+ access and that is sufficiently small to be covered
+ by the single scalar iteration. */
unsigned HOST_WIDE_INT cnunits, cvf, cremain, cpart_size;
if (!nunits.is_constant (&cnunits)
|| !LOOP_VINFO_VECT_FACTOR (loop_vinfo).is_constant (&cvf)
- || ((cremain = remain.to_constant (), true)
+ || (((cremain = group_size * cvf - gap % cnunits), true)
&& ((cpart_size = (1 << ceil_log2 (cremain))) != cnunits)
- && vector_vector_composition_type
- (vectype, cnunits / cpart_size,
- &half_vtype) == NULL_TREE))
+ && (cremain + group_size < cpart_size
+ || vector_vector_composition_type
+ (vectype, cnunits / cpart_size,
+ &half_vtype) == NULL_TREE)))
{
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
--
2.35.3
