[gcc(refs/users/aoliva/heads/testbase)] tree-optimization/96783 - fix vectorization of negative step SLP
Alexandre Oliva
aoliva@gcc.gnu.org
Thu Sep 3 15:49:40 GMT 2020
https://gcc.gnu.org/g:71b6257e3a90995e1c1d3d2716a0eec5eef243db
commit 71b6257e3a90995e1c1d3d2716a0eec5eef243db
Author: Richard Biener <rguenther@suse.de>
Date: Wed Aug 26 14:24:01 2020 +0200
tree-optimization/96783 - fix vectorization of negative step SLP
This appropriately uses VMAT_ELEMENTWISE when the vectors cannot be
filled from a single SLP group until we get more explicit support
for negative stride SLP.
2020-08-26 Richard Biener <rguenther@suse.de>
PR tree-optimization/96783
* tree-vect-stmts.c (get_group_load_store_type): Use
VMAT_ELEMENTWISE for negative strides when we cannot
use VMAT_STRIDED_SLP.
* gcc.dg/vect/pr96783-1.c: New testcase.
* gcc.dg/vect/pr96783-2.c: Likewise.
Diff:
---
gcc/testsuite/gcc.dg/vect/pr96783-1.c | 38 +++++++++++++++++++++++++++++++++++
gcc/testsuite/gcc.dg/vect/pr96783-2.c | 29 ++++++++++++++++++++++++++
gcc/tree-vect-stmts.c | 10 ++++++++-
3 files changed, 76 insertions(+), 1 deletion(-)
diff --git a/gcc/testsuite/gcc.dg/vect/pr96783-1.c b/gcc/testsuite/gcc.dg/vect/pr96783-1.c
new file mode 100644
index 00000000000..55d1364f056
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr96783-1.c
@@ -0,0 +1,38 @@
+/* { dg-do run } */
+
+#include "tree-vect.h"
+
+void __attribute__((noipa))
+foo (long *a, int off, int n)
+{
+ for (int i = 0; i < n; ++i)
+ {
+ long tem1 = a[0];
+ long tem2 = a[1];
+ long tem3 = a[2];
+ long tem4 = a[off + 1];
+ a[0] = tem4;
+ long tem5 = a[off + 2];
+ a[1] = tem5;
+ long tem6 = a[off + 3];
+ a[2] = tem6;
+ a[off + 1] = tem1;
+ a[off + 2] = tem2;
+ a[off + 3] = tem3;
+ a -= 3;
+ }
+}
+
+int main ()
+{
+ long a[3 * 9];
+ check_vect ();
+ for (int i = 0; i < 3 * 9; ++i)
+ a[i] = i;
+ foo (a + 3 * 5, 6-1, 5);
+ const long b[3 * 8] = { 0, 1, 2, 21, 22, 23, 18, 19, 20, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 };
+ for (int i = 0; i < 3 * 8; ++i)
+ if (a[i] != b[i])
+ __builtin_abort ();
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/vect/pr96783-2.c b/gcc/testsuite/gcc.dg/vect/pr96783-2.c
new file mode 100644
index 00000000000..33c37109e3a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr96783-2.c
@@ -0,0 +1,29 @@
+/* { dg-do run } */
+
+#include "tree-vect.h"
+
+long a[1024];
+long b[1024];
+
+void __attribute__((noipa)) foo ()
+{
+ for (int i = 0; i < 256; ++i)
+ {
+ a[3*i] = b[1023 - 3*i - 2];
+ a[3*i + 1] = b[1023 - 3*i - 1];
+ a[3*i + 2] = b[1023 - 3*i];
+ }
+}
+
+int main()
+{
+ for (int i = 0; i < 1024; ++i)
+ b[i] = i;
+ foo ();
+ for (int i = 0; i < 256; ++i)
+ if (a[3*i] != 1023 - 3*i - 2
+ || a[3*i+1] != 1023 - 3*i - 1
+ || a[3*i+2] != 1023 - 3*i)
+ __builtin_abort ();
+ return 0;
+}
diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 65e30bac424..224be018af9 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -2192,7 +2192,15 @@ get_group_load_store_type (vec_info *vinfo, stmt_vec_info stmt_info,
*memory_access_type = get_negative_load_store_type
(vinfo, stmt_info, vectype, vls_type, 1);
else
- *memory_access_type = VMAT_STRIDED_SLP;
+ {
+ /* Try to use consecutive accesses of DR_GROUP_SIZE elements,
+ separated by the stride, until we have a complete vector.
+ Fall back to scalar accesses if that isn't possible. */
+ if (multiple_p (nunits, group_size))
+ *memory_access_type = VMAT_STRIDED_SLP;
+ else
+ *memory_access_type = VMAT_ELEMENTWISE;
+ }
}
else
{
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