[PATCH] vect: Fix shift-by-induction for single-lane slp
Feng Xue OS
fxue@os.amperecomputing.com
Thu Jun 27 15:15:17 GMT 2024
I added two test cases for the examples your mentioned.
BTW: would you please look over another 3 lane-reducing patches that have been updated? If ok, I would consider to check them in.
Thanks,
Feng
--
Allow shift-by-induction for slp node, when it is single lane, which is
aligned with the original loop-based handling.
gcc/
* tree-vect-stmts.cc (vectorizable_shift): Allow shift-by-induction
for single-lane slp node.
gcc/testsuite/
* gcc.dg/vect/vect-shift-6.c
* gcc.dg/vect/vect-shift-7.c
---
gcc/testsuite/gcc.dg/vect/vect-shift-6.c | 51 +++++++++++++++++++
gcc/testsuite/gcc.dg/vect/vect-shift-7.c | 65 ++++++++++++++++++++++++
gcc/tree-vect-stmts.cc | 2 +-
3 files changed, 117 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-shift-6.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-shift-7.c
diff --git a/gcc/testsuite/gcc.dg/vect/vect-shift-6.c b/gcc/testsuite/gcc.dg/vect/vect-shift-6.c
new file mode 100644
index 00000000000..940f7f2a4db
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-shift-6.c
@@ -0,0 +1,51 @@
+/* { dg-require-effective-target vect_shift } */
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+#define N 32
+
+int A[N];
+int B[N];
+
+#define FN(name) \
+__attribute__((noipa)) \
+void name(int *a) \
+{ \
+ for (int i = 0; i < N / 2; i++) \
+ { \
+ a[2 * i + 0] <<= i; \
+ a[2 * i + 1] <<= i; \
+ } \
+}
+
+
+FN(foo_vec)
+
+#pragma GCC push_options
+#pragma GCC optimize ("O0")
+FN(foo_novec)
+#pragma GCC pop_options
+
+int main ()
+{
+ int i;
+
+ check_vect ();
+
+#pragma GCC novector
+ for (i = 0; i < N; i++)
+ A[i] = B[i] = -(i + 1);
+
+ foo_vec(A);
+ foo_novec(B);
+
+ /* check results: */
+#pragma GCC novector
+ for (i = 0; i < N; i++)
+ if (A[i] != B[i])
+ abort ();
+
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/vect/vect-shift-7.c b/gcc/testsuite/gcc.dg/vect/vect-shift-7.c
new file mode 100644
index 00000000000..a33b120343b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-shift-7.c
@@ -0,0 +1,65 @@
+/* { dg-require-effective-target vect_shift } */
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+#define N 32
+#define M 64
+
+int A[N];
+int B[N];
+
+#define FN(name) \
+__attribute__((noipa)) \
+void name(int *a) \
+{ \
+ for (int i = 0; i < N / 2; i++) \
+ { \
+ int s1 = i; \
+ int s2 = s1 + 1; \
+ int r1 = 0; \
+ int r2 = 1; \
+ \
+ for (int j = 0; j < M; j++) \
+ { \
+ r1 += j << s1; \
+ r2 += j << s2; \
+ s1++; \
+ s2++; \
+ } \
+ \
+ a[2 * i + 0] = r1; \
+ a[2 * i + 1] = r2; \
+ } \
+}
+
+
+FN(foo_vec)
+
+#pragma GCC push_options
+#pragma GCC optimize ("O0")
+FN(foo_novec)
+#pragma GCC pop_options
+
+int main ()
+{
+ int i;
+
+ check_vect ();
+
+#pragma GCC novector
+ for (i = 0; i < N; i++)
+ A[i] = B[i] = 0;
+
+ foo_vec(A);
+ foo_novec(B);
+
+ /* check results: */
+#pragma GCC novector
+ for (i = 0; i < N; i++)
+ if (A[i] != B[i])
+ abort ();
+
+ return 0;
+}
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index ca6052662a3..840e162c7f0 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -6247,7 +6247,7 @@ vectorizable_shift (vec_info *vinfo,
if ((dt[1] == vect_internal_def
|| dt[1] == vect_induction_def
|| dt[1] == vect_nested_cycle)
- && !slp_node)
+ && (!slp_node || SLP_TREE_LANES (slp_node) == 1))
scalar_shift_arg = false;
else if (dt[1] == vect_constant_def
|| dt[1] == vect_external_def
--
2.17.1
________________________________________
From: Richard Biener <richard.guenther@gmail.com>
Sent: Thursday, June 27, 2024 12:49 AM
To: Feng Xue OS
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] vect: Fix shift-by-induction for single-lane slp
On Wed, Jun 26, 2024 at 4:58 PM Feng Xue OS <fxue@os.amperecomputing.com> wrote:
>
> Allow shift-by-induction for slp node, when it is single lane, which is
> aligned with the original loop-based handling.
OK.
Did you try whether we handle multiple lanes correctly? The simplest
case would be a loop
body with say
a[2*i] = x << i;
a[2*i+1] = x << i;
I'm not sure how we match up multiple (different) inductions in the
same SLP node,
but one node could be x << (i + 1).
Note you enable a nested cycle def the same way, I think that could be
treated like
an internal def and also generally. There's probably no test coverage
for that though.
Sth like
for (m ...)
{
i = m;
j = i + 1;
for (k ...)
{
res1 += k << i;
res2 += k << j;
i++;
j++;
}
a[2*m] = res1;
a[2*m+1] = res2;
}
Thanks,
Richard.
> Thanks,
> Feng
>
> ---
> gcc/tree-vect-stmts.cc | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
> index ca6052662a3..840e162c7f0 100644
> --- a/gcc/tree-vect-stmts.cc
> +++ b/gcc/tree-vect-stmts.cc
> @@ -6247,7 +6247,7 @@ vectorizable_shift (vec_info *vinfo,
> if ((dt[1] == vect_internal_def
> || dt[1] == vect_induction_def
> || dt[1] == vect_nested_cycle)
> - && !slp_node)
> + && (!slp_node || SLP_TREE_LANES (slp_node) == 1))
> scalar_shift_arg = false;
> else if (dt[1] == vect_constant_def
> || dt[1] == vect_external_def
> --
> 2.17.1
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