Hi!
As discussed in the PR, the reduction code isn't able to cope with type
promotions/demotions in the reduction computation, so if we recognize an
over-widening pattern that has vect_reduction_def type, we most likely make
it non-vectorizable.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
turnk?
2021-02-02 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/98848
* tree-vect-patterns.c (vect_recog_over_widening_pattern): Punt if
STMT_VINFO_DEF_TYPE (last_stmt_info) is vect_reduction_def.
* gcc.dg/vect/pr98848.c: New test.
* gcc.dg/vect/pr92205.c: Remove xfail.
--- gcc/tree-vect-patterns.c.jj 2021-01-04 10:25:38.650235896 +0100
+++ gcc/tree-vect-patterns.c 2021-02-01 11:04:48.136814236 +0100
@@ -1579,6 +1579,10 @@ vect_recog_over_widening_pattern (vec_in
tree type = TREE_TYPE (lhs);
tree_code code = gimple_assign_rhs_code (last_stmt);
+ /* Punt for reductions where we don't handle the type conversions. */
+ if (STMT_VINFO_DEF_TYPE (last_stmt_info) == vect_reduction_def)
+ return NULL;
+
/* Keep the first operand of a COND_EXPR as-is: only the other two
operands are interesting. */
unsigned int first_op = (code == COND_EXPR ? 2 : 1);
--- gcc/testsuite/gcc.dg/vect/pr98848.c.jj 2021-02-01 11:15:11.965633750
+0100
+++ gcc/testsuite/gcc.dg/vect/pr98848.c 2021-02-01 11:15:07.348686891 +0100
@@ -0,0 +1,18 @@
+/* PR tree-optimization/98848 */
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+
+short a[9000];
+
+int
+foo (void)
+{
+ int b = a[0];
+ int i;
+ for (i = 1; i < 9000; i ++)
+ if (a[i] < b)
+ b = a[i];
+ return b;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loop" 1 "vect" { xfail {
vect_no_int_add || vect_no_int_min_max } } } } */
--- gcc/testsuite/gcc.dg/vect/pr92205.c.jj 2020-01-12 11:54:37.645394821
+0100
+++ gcc/testsuite/gcc.dg/vect/pr92205.c 2021-02-02 09:59:40.998104863 +0100
@@ -10,4 +10,4 @@ int b(int n, unsigned char *a)
return d;
}
-/* { dg-final { scan-tree-dump "vectorized 1 loops" "vect" { xfail *-*-* } } }
*/
+/* { dg-final { scan-tree-dump "vectorized 1 loops" "vect" { target {
vect_unpack && { ! vect_no_bitwise } } } } } */
Jakub
