https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95570
Bug ID: 95570
Summary: ICE: Segmentation fault in vect_loop_versioning
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: felix.yang at huawei dot com
Target Milestone: ---
Target: aarch64
foo.c:
int x[8][32];
void
foo (int start)
{
for (int i = start; i < start + 16; i++)
x[start][i] = i;
}
$ gcc -S -O2 -ftree-loop-vectorize -march=armv8.2-a+sve -msve-vector-bits=256
-fno-vect-cost-model -fwrapv -mstrict-align foo.c
during GIMPLE pass: vect
foo.c: In function ‘foo’:
foo.c:4:1: internal compiler error: Segmentation fault
4 | foo (int start)
| ^~~
0x12bb79b crash_signal
../../gcc-git/gcc/toplev.c:328
0x94cc4c contains_struct_check(tree_node const*, tree_node_structure_enum, char
const*, int, char const*)
../../gcc-git/gcc/tree.h:3665
0x9893db wi::extended_tree<576>::extended_tree(tree_node const*)
../../gcc-git/gcc/tree.h:5922
0x987e9b generic_wide_int<wi::extended_tree<576> >::generic_wide_int<tree_node
const*>(tree_node const* const&)
../../gcc-git/gcc/wide-int.h:782
0x98796f wi::to_widest(tree_node const*)
../../gcc-git/gcc/tree.h:5849
0xa84e13 tree_int_cst_compare(tree_node const*, tree_node const*)
../../gcc-git/gcc/tree.h:6121
0x16911bb vect_create_cond_for_align_checks
../../gcc-git/gcc/tree-vect-loop-manip.c:3055
0x1691a1f vect_loop_versioning(_loop_vec_info*, gimple*)
../../gcc-git/gcc/tree-vect-loop-manip.c:3263
0x167ffbb vect_transform_loop(_loop_vec_info*, gimple*)
../../gcc-git/gcc/tree-vect-loop.c:8691
0x16ac56b try_vectorize_loop_1
../../gcc-git/gcc/tree-vectorizer.c:989
0x16ac7e7 try_vectorize_loop
../../gcc-git/gcc/tree-vectorizer.c:1046
0x16ac997 vectorize_loops()
../../gcc-git/gcc/tree-vectorizer.c:1125
0x1507e2b execute
../../gcc-git/gcc/tree-ssa-loop.c:414
Here, we are doing loop versionging for alignment.
The only dr here is a gather-statter operation: x[start][i].
Scalar evolution analysis for this dr failed, so DR_STEP is NULL_TREE, which
leads to the segfault.
But scatter-gather operation should be filtered out in
vect_enhance_data_refs_alignment.
Like:
@@ -2206,6 +2228,12 @@ vect_enhance_data_refs_alignment (loop_vec_info
loop_vinfo)
&& DR_GROUP_FIRST_ELEMENT (stmt_info) != stmt_info))
continue;
+ /* For scatter-gather or invariant accesses there is nothing
+ to enhance. */
+ if (STMT_VINFO_GATHER_SCATTER_P (stmt_info)
+ || integer_zerop (DR_STEP (dr)))
+ continue;
+
if (STMT_VINFO_STRIDED_P (stmt_info))
{
/* Strided loads perform only component accesses, alignment is
I also witnessed similar issues in vect_verify_datarefs_alignment,
vect_get_peeling_costs_all_drs and vect_peeling_supportable. Since the code is
similar, maybe we should propose a new funtion for that. Suggestions?
