This fixes a condition that caused all negative step DR groups to
be detected as single element interleaving. Such groups are
rejected by interleaving vectorization but miscompiled by SLP
which is fixed by forcing VMAT_STRIDED_SLP for now.
Bootstrap & regtest running on x86_64-unknown-linux-gnu.
* tree-vect-data-refs.c (vect_analyze_data_ref_accesses): Fix
group overlap condition to allow negative step DR groups.
* tree-vect-stmts.c (get_group_load_store_type): For
multi element SLP groups force VMAT_STRIDED_SLP when the step
is negative.
* gcc.dg/vect/slp-47.c: New testcase.
* gcc.dg/vect/slp-48.c: Likewise.
---
gcc/testsuite/gcc.dg/vect/slp-47.c | 56 ++++++++++++++++++++++++++++++
gcc/testsuite/gcc.dg/vect/slp-48.c | 56 ++++++++++++++++++++++++++++++
gcc/tree-vect-data-refs.c | 8 +++--
gcc/tree-vect-stmts.c | 11 ++++--
4 files changed, 126 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/vect/slp-47.c
create mode 100644 gcc/testsuite/gcc.dg/vect/slp-48.c
diff --git a/gcc/testsuite/gcc.dg/vect/slp-47.c
b/gcc/testsuite/gcc.dg/vect/slp-47.c
new file mode 100644
index 00000000000..7b2ddf664df
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/slp-47.c
@@ -0,0 +1,56 @@
+/* { dg-require-effective-target vect_int } */
+
+#include "tree-vect.h"
+
+int x[1024], y[1024];
+
+void __attribute__((noipa)) foo()
+{
+ for (int i = 0; i < 512; ++i)
+ {
+ x[2*i] = y[1023 - (2*i)];
+ x[2*i+1] = y[1023 - (2*i+1)];
+ }
+}
+
+void __attribute__((noipa)) bar()
+{
+ for (int i = 0; i < 512; ++i)
+ {
+ x[2*i] = y[1023 - (2*i+1)];
+ x[2*i+1] = y[1023 - (2*i)];
+ }
+}
+
+int
+main ()
+{
+ check_vect ();
+
+ for (int i = 0; i < 1024; ++i)
+ {
+ x[i] = 0;
+ y[i] = i;
+ __asm__ volatile ("");
+ }
+
+ foo ();
+ for (int i = 0; i < 1024; ++i)
+ if (x[i] != y[1023 - i])
+ abort ();
+
+ for (int i = 0; i < 1024; ++i)
+ {
+ x[i] = 0;
+ __asm__ volatile ("");
+ }
+
+ bar ();
+ for (int i = 0; i < 1024; ++i)
+ if (x[i] != y[1023 - i^1])
+ abort ();
+
+ return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorizing stmts using SLP" 2 "vect" }
} */
diff --git a/gcc/testsuite/gcc.dg/vect/slp-48.c
b/gcc/testsuite/gcc.dg/vect/slp-48.c
new file mode 100644
index 00000000000..0b327aede8e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/slp-48.c
@@ -0,0 +1,56 @@
+/* { dg-require-effective-target vect_int } */
+
+#include "tree-vect.h"
+
+int x[1024], y[1024];
+
+void __attribute__((noipa)) foo()
+{
+ for (int i = 0; i < 512; ++i)
+ {
+ x[1023 - (2*i+1)] = y[2*i];
+ x[1023 - (2*i)] = y[2*i+1];
+ }
+}
+
+void __attribute__((noipa)) bar()
+{
+ for (int i = 0; i < 512; ++i)
+ {
+ x[1023 - (2*i+1)] = y[2*i+1];
+ x[1023 - (2*i)] = y[2*i];
+ }
+}
+
+int
+main ()
+{
+ check_vect ();
+
+ for (int i = 0; i < 1024; ++i)
+ {
+ x[i] = 0;
+ y[i] = i;
+ __asm__ volatile ("");
+ }
+
+ foo ();
+ for (int i = 0; i < 1024; ++i)
+ if (x[i] != y[1023 - i^1])
+ abort ();
+
+ for (int i = 0; i < 1024; ++i)
+ {
+ x[i] = 0;
+ __asm__ volatile ("");
+ }
+
+ bar ();
+ for (int i = 0; i < 1024; ++i)
+ if (x[i] != y[1023 - i])
+ abort ();
+
+ return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorizing stmts using SLP" 2 "vect" }
} */
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index 959c2d3378f..2b4421b5fb4 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -3074,13 +3074,15 @@ vect_analyze_data_ref_accesses (vec_info *vinfo)
if (!DR_IS_READ (dra) && init_b - init_prev != type_size_a)
break;
- /* If the step (if not zero or non-constant) is greater than the
+ /* If the step (if not zero or non-constant) is smaller than the
difference between data-refs' inits this splits groups into
suitable sizes. */
if (tree_fits_shwi_p (DR_STEP (dra)))
{
- HOST_WIDE_INT step = tree_to_shwi (DR_STEP (dra));
- if (step != 0 && step <= (init_b - init_a))
+ unsigned HOST_WIDE_INT step
+ = absu_hwi (tree_to_shwi (DR_STEP (dra)));
+ if (step != 0
+ && step <= (unsigned HOST_WIDE_INT)(init_b - init_a))
break;
}
}
diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index f66c5f5b367..fcae3ef5f35 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -2150,8 +2150,15 @@ get_group_load_store_type (vec_info *vinfo,
stmt_vec_info stmt_info,
}
int cmp = compare_step_with_zero (vinfo, stmt_info);
if (cmp < 0)
- *memory_access_type = get_negative_load_store_type
- (vinfo, stmt_info, vectype, vls_type, 1);
+ {
+ if (single_element_p)
+ /* ??? The VMAT_CONTIGUOUS_REVERSE code generation is
+ only correct for single element "interleaving" SLP. */
+ *memory_access_type = get_negative_load_store_type
+ (vinfo, stmt_info, vectype, vls_type, 1);
+ else
+ *memory_access_type = VMAT_STRIDED_SLP;
+ }
else
{
gcc_assert (!loop_vinfo || cmp > 0);
--
2.26.2
