Bootstrapped and tested on powerpc64-suse-linux.
Committed to trunk.
Ira
ChangeLog:
* tree-vect-data-refs.c (vect_analyze_data_ref_dependence): Allow
read-after-read dependencies in basic block SLP.
testsuite/ChangeLog:
* gcc.dg/vect/bb-slp-25.c: New.
Index: tree-vect-data-refs.c
===================================================================
--- tree-vect-data-refs.c (revision 178879)
+++ tree-vect-data-refs.c (working copy)
@@ -607,6 +607,11 @@ vect_analyze_data_ref_dependence (struct data_depe
if (vect_check_interleaving (dra, drb))
return false;
+ /* Read-read is OK (we need this check here, after checking for
+ interleaving). */
+ if (DR_IS_READ (dra) && DR_IS_READ (drb))
+ return false;
+
if (vect_print_dump_info (REPORT_DR_DETAILS))
{
fprintf (vect_dump, "can't determine dependence between ");
Index: testsuite/gcc.dg/vect/bb-slp-25.c
===================================================================
--- testsuite/gcc.dg/vect/bb-slp-25.c (revision 0)
+++ testsuite/gcc.dg/vect/bb-slp-25.c (revision 0)
@@ -0,0 +1,57 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+#define A 3
+#define B 4
+#define N 256
+
+short src[N], dst[N];
+
+void foo (short * __restrict dst, short * __restrict src, int h, int stride)
+{
+ int i;
+ h /= 16;
+ for (i = 0; i < h; i++)
+ {
+ dst[0] += A*src[0] + src[stride];
+ dst[1] += A*src[1] + src[1+stride];
+ dst[2] += A*src[2] + src[2+stride];
+ dst[3] += A*src[3] + src[3+stride];
+ dst[4] += A*src[4] + src[4+stride];
+ dst[5] += A*src[5] + src[5+stride];
+ dst[6] += A*src[6] + src[6+stride];
+ dst[7] += A*src[7] + src[7+stride];
+ dst += 8;
+ src += 8;
+ }
+}
+
+
+int main (void)
+{
+ int i;
+
+ check_vect ();
+
+ for (i = 0; i < N; i++)
+ {
+ dst[i] = 0;
+ src[i] = i;
+ }
+
+ foo (dst, src, N, 8);
+
+ for (i = 0; i < N/2; i++)
+ {
+ if (dst[i] != A * i + i + 8)
+ abort ();
+ }
+
+ return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "basic block vectorized using
SLP" 1 "slp" { target vect_element_align } } } */
+/* { dg-final { cleanup-tree-dump "slp" } } */
+
