# vect: Support multiple lane-reducing operations for loop reduction [PR114440]

Message ID LV2PR01MB783908343529A6204C432BC2F7012@LV2PR01MB7839.prod.exchangelabs.com New vect: Support multiple lane-reducing operations for loop reduction [PR114440] |

## Checks

Context Check Description
linaro-tcwg-bot/tcwg_gcc_build--master-arm fail Patch failed to apply
linaro-tcwg-bot/tcwg_gcc_build--master-aarch64 fail Patch failed to apply

## Commit Message

Feng Xue OS April 7, 2024, 6:59 a.m. UTC
```  For lane-reducing operation(dot-prod/widen-sum/sad) in loop reduction, current
vectorizer could only handle the pattern if the reduction chain does not
contain other operation, no matter the other is normal or lane-reducing.

Acctually, to allow multiple arbitray lane-reducing operations, we need to
support vectorization of loop reduction chain with mixed input vectypes. Since
lanes of vectype may vary with operation, the effective ncopies of vectorized
statements for operation also may not be same to each other, this causes
mismatch on vectorized def-use cycles. A simple way is to align all operations
with the one that has the most ncopies, the gap could be complemented by
generating extra trival pass-through copies. For example:

int sum = 0;
for (i)
{
sum += d0[i] * d1[i];      // dot-prod <vector(16) char>
sum += w[i];               // widen-sum <vector(16) short>
sum += abs(s0[i] - s1[i]); // sad <vector(8) short>
sum += n[i];               // normal <vector(4) int>
}

The vector size is 128-bit，vectorization factor is 16. Reduction statements
would be transformed as:

vector<4> int sum_v0 = { 0, 0, 0, 0 };
vector<4> int sum_v1 = { 0, 0, 0, 0 };
vector<4> int sum_v2 = { 0, 0, 0, 0 };
vector<4> int sum_v3 = { 0, 0, 0, 0 };

for (i / 16)
{
sum_v0 = DOT_PROD (d0_v0[i: 0 ~ 15], d1_v0[i: 0 ~ 15], sum_v0);
sum_v1 = sum_v1;  // copy
sum_v2 = sum_v2;  // copy
sum_v3 = sum_v3;  // copy

sum_v0 = sum_v0;  // copy
sum_v1 = WIDEN_SUM (w_v1[i: 0 ~ 15], sum_v1);
sum_v2 = sum_v2;  // copy
sum_v3 = sum_v3;  // copy

sum_v0 = sum_v0;  // copy
sum_v1 = sum_v1;  // copy
sum_v2 = SAD (s0_v2[i: 0 ~ 7 ], s1_v2[i: 0 ~ 7 ], sum_v2);
sum_v3 = SAD (s0_v3[i: 8 ~ 15], s1_v3[i: 8 ~ 15], sum_v3);

sum_v0 += n_v0[i: 0  ~ 3 ];
sum_v1 += n_v1[i: 4  ~ 7 ];
sum_v2 += n_v2[i: 8  ~ 11];
sum_v3 += n_v3[i: 12 ~ 15];
}

Moreover, for a higher instruction parallelism in final vectorized loop, it
is considered to make those effective vectorized lane-reducing statements be
distributed evenly among all def-use cycles. In the above example, DOT_PROD,
WIDEN_SUM and SADs are generated into disparate cycles.

Bootstrapped/regtested on x86_64-linux and aarch64-linux.

Feng
-------
gcc/
PR tree-optimization/114440
* tree-vectorizer.h (struct _stmt_vec_info): Add a new field
reduc_result_pos.
(vectorizable_lane_reducing): New function declaration.
* tree-vect-stmts.cc (vectorizable_condition): Treat the condition
statement that is pointed by stmt_vec_info of reduction PHI as the
real "for_reduction" statement.
(vect_analyze_stmt): Call new function vectorizable_lane_reducing
to analyze lane-reducing operation.
* tree-vect-loop.cc (vect_is_emulated_mixed_dot_prod): Remove parameter
loop_vinfo. Get input vectype from stmt_info instead of reduction PHI.
(vect_model_reduction_cost): Remove cost computation code related to
emulated_mixed_dot_prod.
(vect_reduction_use_partial_vector): New function.
(vectorizable_lane_reducing): New function.
(vectorizable_reduction): Allow multiple lane-reducing operations in
loop reduction. Move some original lane-reducing related code to
vectorizable_lane_reducing, and move partial vectorization checking
code to vect_reduction_use_partial_vector.
(vect_transform_reduction): Extend transformation to support reduction
statements with mixed input vectypes.

gcc/testsuite/
PR tree-optimization/114440
* gcc.dg/vect/vect-reduc-chain-1.c
* gcc.dg/vect/vect-reduc-chain-2.c
* gcc.dg/vect/vect-reduc-chain-3.c
* gcc.dg/vect/vect-reduc-dot-slp-1.c
* gcc.dg/vect/vect-reduc-dot-slp-2.c
---
.../gcc.dg/vect/vect-reduc-chain-1.c          |  62 ++
.../gcc.dg/vect/vect-reduc-chain-2.c          |  77 ++
.../gcc.dg/vect/vect-reduc-chain-3.c          |  66 ++
.../gcc.dg/vect/vect-reduc-dot-slp-1.c        |  97 +++
.../gcc.dg/vect/vect-reduc-dot-slp-2.c        |  81 +++
gcc/tree-vect-loop.cc                         | 668 ++++++++++++------
gcc/tree-vect-stmts.cc                        |  13 +-
gcc/tree-vectorizer.h                         |   8 +
8 files changed, 863 insertions(+), 209 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-1.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-2.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-3.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-1.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-2.c
```

## Patch

```From ecde6210ff483ad899a2eeba91aa1b623c49173a Mon Sep 17 00:00:00 2001
From: Feng Xue <fxue@os.amperecomputing.com>
Date: Fri, 22 Mar 2024 19:57:45 +0800
Subject: [PATCH] vect: Support multiple lane-reducing operations for loop
reduction [PR114440]

gcc/
PR tree-optimization/114440
* tree-vectorizer.h (struct _stmt_vec_info): Add a new field
reduc_result_pos.
(vectorizable_lane_reducing): New function declaration.
* tree-vect-stmts.cc (vectorizable_condition): Treat the condition
statement that is pointed by stmt_vec_info of reduction PHI as the
real "for_reduction" statement.
(vect_analyze_stmt): Call new function vectorizable_lane_reducing
to analyze lane-reducing operation.
* tree-vect-loop.cc (vect_is_emulated_mixed_dot_prod): Remove parameter
loop_vinfo. Get input vectype from stmt_info instead of reduction PHI.
(vect_model_reduction_cost): Remove cost computation code related to
emulated_mixed_dot_prod.
(vect_reduction_use_partial_vector): New function.
(vectorizable_lane_reducing): New function.
(vectorizable_reduction): Allow multiple lane-reducing operations in
loop reduction. Move some original lane-reducing related code to
vectorizable_lane_reducing, and move partial vectorization checking
code to vect_reduction_use_partial_vector.
(vect_transform_reduction): Extend transformation to support reduction
statements with mixed input vectypes.

gcc/testsuite/
PR tree-optimization/114440
* gcc.dg/vect/vect-reduc-chain-1.c
* gcc.dg/vect/vect-reduc-chain-2.c
* gcc.dg/vect/vect-reduc-chain-3.c
* gcc.dg/vect/vect-reduc-dot-slp-1.c
* gcc.dg/vect/vect-reduc-dot-slp-2.c
---
.../gcc.dg/vect/vect-reduc-chain-1.c          |  62 ++
.../gcc.dg/vect/vect-reduc-chain-2.c          |  77 ++
.../gcc.dg/vect/vect-reduc-chain-3.c          |  66 ++
.../gcc.dg/vect/vect-reduc-dot-slp-1.c        |  97 +++
.../gcc.dg/vect/vect-reduc-dot-slp-2.c        |  81 +++
gcc/tree-vect-loop.cc                         | 668 ++++++++++++------
gcc/tree-vect-stmts.cc                        |  13 +-
gcc/tree-vectorizer.h                         |   8 +
8 files changed, 863 insertions(+), 209 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-1.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-2.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-3.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-1.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-2.c

diff --git a/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-1.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-1.c
new file mode 100644
index 00000000000..04bfc419dbd
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-1.c
@@ -0,0 +1,62 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-require-effective-target vect_int } */
+/* { dg-require-effective-target arm_v8_2a_dotprod_neon_hw { target { aarch64*-*-* || arm*-*-* } } } */
+/* { dg-add-options arm_v8_2a_dotprod_neon }  */
+
+#include "tree-vect.h"
+
+#define N 50
+
+#ifndef SIGNEDNESS_1
+#define SIGNEDNESS_1 signed
+#define SIGNEDNESS_2 signed
+#endif
+
+SIGNEDNESS_1 int __attribute__ ((noipa))
+f (SIGNEDNESS_1 int res,
+   SIGNEDNESS_2 char *restrict a,
+   SIGNEDNESS_2 char *restrict b,
+   SIGNEDNESS_2 char *restrict c,
+   SIGNEDNESS_2 char *restrict d,
+   SIGNEDNESS_1 int *restrict e)
+{
+  for (int i = 0; i < N; ++i)
+    {
+      res += a[i] * b[i];
+      res += c[i] * d[i];
+      res += e[i];
+    }
+  return res;
+}
+
+#define BASE ((SIGNEDNESS_2 int) -1 < 0 ? -126 : 4)
+#define OFFSET 20
+
+int
+main (void)
+{
+  check_vect ();
+
+  SIGNEDNESS_2 char a[N], b[N];
+  SIGNEDNESS_2 char c[N], d[N];
+  SIGNEDNESS_1 int e[N];
+  int expected = 0x12345;
+  for (int i = 0; i < N; ++i)
+    {
+      a[i] = BASE + i * 5;
+      b[i] = BASE + OFFSET + i * 4;
+      c[i] = BASE + i * 2;
+      d[i] = BASE + OFFSET + i * 3;
+      e[i] = i;
+      asm volatile ("" ::: "memory");
+      expected += a[i] * b[i];
+      expected += c[i] * d[i];
+      expected += e[i];
+    }
+  if (f (0x12345, a, b, c, d, e) != expected)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump "vect_recog_dot_prod_pattern: detected" "vect" } } */
+/* { dg-final { scan-tree-dump-times "vectorizing statement: \\S+ = DOT_PROD_EXPR" 2 "vect" { target vect_sdot_qi } } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-2.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-2.c
new file mode 100644
index 00000000000..6c803b80120
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-2.c
@@ -0,0 +1,77 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-require-effective-target vect_int } */
+/* { dg-require-effective-target arm_v8_2a_dotprod_neon_hw { target { aarch64*-*-* || arm*-*-* } } } */
+/* { dg-add-options arm_v8_2a_dotprod_neon }  */
+
+#include "tree-vect.h"
+
+#define N 50
+
+#ifndef SIGNEDNESS_1
+#define SIGNEDNESS_1 signed
+#define SIGNEDNESS_2 unsigned
+#define SIGNEDNESS_3 signed
+#define SIGNEDNESS_4 signed
+#endif
+
+SIGNEDNESS_1 int __attribute__ ((noipa))
+fn (SIGNEDNESS_1 int res,
+   SIGNEDNESS_2 char *restrict a,
+   SIGNEDNESS_2 char *restrict b,
+   SIGNEDNESS_3 char *restrict c,
+   SIGNEDNESS_3 char *restrict d,
+   SIGNEDNESS_4 short *restrict e,
+   SIGNEDNESS_4 short *restrict f,
+   SIGNEDNESS_1 int *restrict g)
+{
+  for (int i = 0; i < N; ++i)
+    {
+      res += a[i] * b[i];
+      res += i + 1;
+      res += c[i] * d[i];
+      res += e[i] * f[i];
+      res += g[i];
+    }
+  return res;
+}
+
+#define BASE2 ((SIGNEDNESS_2 int) -1 < 0 ? -126 : 4)
+#define BASE3 ((SIGNEDNESS_3 int) -1 < 0 ? -126 : 4)
+#define BASE4 ((SIGNEDNESS_4 int) -1 < 0 ? -1026 : 373)
+#define OFFSET 20
+
+int
+main (void)
+{
+  check_vect ();
+
+  SIGNEDNESS_2 char a[N], b[N];
+  SIGNEDNESS_3 char c[N], d[N];
+  SIGNEDNESS_4 short e[N], f[N];
+  SIGNEDNESS_1 int g[N];
+  int expected = 0x12345;
+  for (int i = 0; i < N; ++i)
+    {
+      a[i] = BASE2 + i * 5;
+      b[i] = BASE2 + OFFSET + i * 4;
+      c[i] = BASE3 + i * 2;
+      d[i] = BASE3 + OFFSET + i * 3;
+      e[i] = BASE4 + i * 6;
+      f[i] = BASE4 + OFFSET + i * 5;
+      g[i] = i;
+      asm volatile ("" ::: "memory");
+      expected += a[i] * b[i];
+      expected += i + 1;
+      expected += c[i] * d[i];
+      expected += e[i] * f[i];
+      expected += g[i];
+    }
+  if (fn (0x12345, a, b, c, d, e, f, g) != expected)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump "vect_recog_dot_prod_pattern: detected" "vect" } } */
+/* { dg-final { scan-tree-dump "vectorizing statement: \\S+ = DOT_PROD_EXPR" "vect" { target { vect_sdot_qi } } } } */
+/* { dg-final { scan-tree-dump "vectorizing statement: \\S+ = DOT_PROD_EXPR" "vect" { target { vect_udot_qi } } } } */
+/* { dg-final { scan-tree-dump "vectorizing statement: \\S+ = DOT_PROD_EXPR" "vect" { target { vect_sdot_hi } } } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-3.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-3.c
new file mode 100644
index 00000000000..a41e4b176c4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-3.c
@@ -0,0 +1,66 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-require-effective-target vect_int } */
+
+#include "tree-vect.h"
+
+#define N 50
+
+#ifndef SIGNEDNESS_1
+#define SIGNEDNESS_1 signed
+#define SIGNEDNESS_2 unsigned
+#define SIGNEDNESS_3 signed
+#endif
+
+SIGNEDNESS_1 int __attribute__ ((noipa))
+f (SIGNEDNESS_1 int res,
+   SIGNEDNESS_2 char *restrict a,
+   SIGNEDNESS_2 char *restrict b,
+   SIGNEDNESS_3 short *restrict c,
+   SIGNEDNESS_3 short *restrict d,
+   SIGNEDNESS_1 int *restrict e)
+{
+  for (int i = 0; i < N; ++i)
+    {
+      short diff = a[i] - b[i];
+      SIGNEDNESS_2 short abs = diff < 0 ? -diff : diff;
+      res += abs;
+      res += c[i] * d[i];
+      res += e[i];
+    }
+  return res;
+}
+
+#define BASE2 ((SIGNEDNESS_2 int) -1 < 0 ? -126 : 4)
+#define BASE3 ((SIGNEDNESS_3 int) -1 < 0 ? -1236 : 373)
+#define OFFSET 20
+
+int
+main (void)
+{
+  check_vect ();
+
+  SIGNEDNESS_2 char a[N], b[N];
+  SIGNEDNESS_3 short c[N], d[N];
+  SIGNEDNESS_1 int e[N];
+  int expected = 0x12345;
+  for (int i = 0; i < N; ++i)
+    {
+      a[i] = BASE2 + i * 5;
+      b[i] = BASE2 - i * 4;
+      c[i] = BASE3 + i * 2;
+      d[i] = BASE3 + OFFSET + i * 3;
+      e[i] = i;
+      asm volatile ("" ::: "memory");
+      short diff = a[i] - b[i];
+      SIGNEDNESS_2 short abs = diff < 0 ? -diff : diff;
+      expected += abs;
+      expected += c[i] * d[i];
+      expected += e[i];
+    }
+  if (f (0x12345, a, b, c, d, e) != expected)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump "vectorizing statement: \\S+ = SAD_EXPR" "vect" { target vect_udot_qi } } } */
+/* { dg-final { scan-tree-dump "vectorizing statement: \\S+ = DOT_PROD_EXPR" "vect" { target vect_sdot_hi } } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-1.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-1.c
new file mode 100644
index 00000000000..51ef4eaaed8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-1.c
@@ -0,0 +1,97 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-require-effective-target vect_int } */
+/* { dg-require-effective-target arm_v8_2a_dotprod_neon_hw { target { aarch64*-*-* || arm*-*-* } } } */
+/* { dg-add-options arm_v8_2a_dotprod_neon }  */
+
+#include "tree-vect.h"
+
+#define N 50
+
+#ifndef SIGNEDNESS_1
+#define SIGNEDNESS_1 signed
+#define SIGNEDNESS_2 signed
+#endif
+
+SIGNEDNESS_1 int __attribute__ ((noipa))
+f (SIGNEDNESS_1 int res,
+   SIGNEDNESS_2 char *a,
+   SIGNEDNESS_2 char *b,
+   int step, int n)
+{
+  for (int i = 0; i < n; i++)
+    {
+      res += a[0] * b[0];
+      res += a[1] * b[1];
+      res += a[2] * b[2];
+      res += a[3] * b[3];
+      res += a[4] * b[4];
+      res += a[5] * b[5];
+      res += a[6] * b[6];
+      res += a[7] * b[7];
+      res += a[8] * b[8];
+      res += a[9] * b[9];
+      res += a[10] * b[10];
+      res += a[11] * b[11];
+      res += a[12] * b[12];
+      res += a[13] * b[13];
+      res += a[14] * b[14];
+      res += a[15] * b[15];
+
+      a += step;
+      b += step;
+    }
+
+  return res;
+}
+
+#define BASE ((SIGNEDNESS_2 int) -1 < 0 ? -126 : 4)
+#define OFFSET 20
+
+int
+main (void)
+{
+  check_vect ();
+
+  SIGNEDNESS_2 char a[100], b[100];
+  int expected = 0x12345;
+  int step = 16;
+  int n = 2;
+  int t = 0;
+
+  for (int i = 0; i < sizeof (a) / sizeof (a[0]); ++i)
+    {
+      a[i] = BASE + i * 5;
+      b[i] = BASE + OFFSET + i * 4;
+      asm volatile ("" ::: "memory");
+    }
+
+  for (int i = 0; i < n; i++)
+    {
+      asm volatile ("" ::: "memory");
+      expected += a[t + 0] * b[t + 0];
+      expected += a[t + 1] * b[t + 1];
+      expected += a[t + 2] * b[t + 2];
+      expected += a[t + 3] * b[t + 3];
+      expected += a[t + 4] * b[t + 4];
+      expected += a[t + 5] * b[t + 5];
+      expected += a[t + 6] * b[t + 6];
+      expected += a[t + 7] * b[t + 7];
+      expected += a[t + 8] * b[t + 8];
+      expected += a[t + 9] * b[t + 9];
+      expected += a[t + 10] * b[t + 10];
+      expected += a[t + 11] * b[t + 11];
+      expected += a[t + 12] * b[t + 12];
+      expected += a[t + 13] * b[t + 13];
+      expected += a[t + 14] * b[t + 14];
+      expected += a[t + 15] * b[t + 15];
+      t += step;
+    }
+
+  if (f (0x12345, a, b, step, n) != expected)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump "vect_recog_dot_prod_pattern: detected" "vect" } } */
+/* { dg-final { scan-tree-dump "vectorizing stmts using SLP" "vect" } } */
+/* { dg-final { scan-tree-dump-times "vectorizing statement: \\S+ = DOT_PROD_EXPR" 16 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-2.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-2.c
new file mode 100644
index 00000000000..1532833c3ae
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-2.c
@@ -0,0 +1,81 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-require-effective-target vect_int } */
+/* { dg-require-effective-target arm_v8_2a_dotprod_neon_hw { target { aarch64*-*-* || arm*-*-* } } } */
+/* { dg-add-options arm_v8_2a_dotprod_neon }  */
+
+#include "tree-vect.h"
+
+#define N 50
+
+#ifndef SIGNEDNESS_1
+#define SIGNEDNESS_1 signed
+#define SIGNEDNESS_2 signed
+#endif
+
+SIGNEDNESS_1 int __attribute__ ((noipa))
+f (SIGNEDNESS_1 int res,
+   SIGNEDNESS_2 short *a,
+   SIGNEDNESS_2 short *b,
+   int step, int n)
+{
+  for (int i = 0; i < n; i++)
+    {
+      res += a[0] * b[0];
+      res += a[1] * b[1];
+      res += a[2] * b[2];
+      res += a[3] * b[3];
+      res += a[4] * b[4];
+      res += a[5] * b[5];
+      res += a[6] * b[6];
+      res += a[7] * b[7];
+
+      a += step;
+      b += step;
+    }
+
+  return res;
+}
+
+#define BASE ((SIGNEDNESS_2 int) -1 < 0 ? -1026 : 373)
+#define OFFSET 20
+
+int
+main (void)
+{
+  check_vect ();
+
+  SIGNEDNESS_2 short a[100], b[100];
+  int expected = 0x12345;
+  int step = 8;
+  int n = 2;
+  int t = 0;
+
+  for (int i = 0; i < sizeof (a) / sizeof (a[0]); ++i)
+    {
+      a[i] = BASE + i * 5;
+      b[i] = BASE + OFFSET + i * 4;
+      asm volatile ("" ::: "memory");
+    }
+
+  for (int i = 0; i < n; i++)
+    {
+      asm volatile ("" ::: "memory");
+      expected += a[t + 0] * b[t + 0];
+      expected += a[t + 1] * b[t + 1];
+      expected += a[t + 2] * b[t + 2];
+      expected += a[t + 3] * b[t + 3];
+      expected += a[t + 4] * b[t + 4];
+      expected += a[t + 5] * b[t + 5];
+      expected += a[t + 6] * b[t + 6];
+      expected += a[t + 7] * b[t + 7];
+      t += step;
+    }
+
+  if (f (0x12345, a, b, step, n) != expected)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump "vect_recog_dot_prod_pattern: detected" "vect" } } */
+/* { dg-final { scan-tree-dump "vectorizing stmts using SLP" "vect" } } */
+/* { dg-final { scan-tree-dump-times "vectorizing statement: \\S+ = DOT_PROD_EXPR" 8 "vect"  { target vect_sdot_hi } } } */
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 984636edbc5..5a3339b6594 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -5269,8 +5269,7 @@  have_whole_vector_shift (machine_mode mode)
See vect_emulate_mixed_dot_prod for the actual sequence used.  */

static bool
-vect_is_emulated_mixed_dot_prod (loop_vec_info loop_vinfo,
-				 stmt_vec_info stmt_info)
+vect_is_emulated_mixed_dot_prod (stmt_vec_info stmt_info)
{
gassign *assign = dyn_cast<gassign *> (stmt_info->stmt);
if (!assign || gimple_assign_rhs_code (assign) != DOT_PROD_EXPR)
@@ -5281,10 +5280,9 @@  vect_is_emulated_mixed_dot_prod (loop_vec_info loop_vinfo,
if (TYPE_SIGN (TREE_TYPE (rhs1)) == TYPE_SIGN (TREE_TYPE (rhs2)))
return false;

-  stmt_vec_info reduc_info = info_for_reduction (loop_vinfo, stmt_info);
-  gcc_assert (reduc_info->is_reduc_info);
+  gcc_assert (STMT_VINFO_REDUC_VECTYPE_IN (stmt_info));
return !directly_supported_p (DOT_PROD_EXPR,
-				STMT_VINFO_REDUC_VECTYPE_IN (reduc_info),
+				STMT_VINFO_REDUC_VECTYPE_IN (stmt_info),
optab_vector_mixed_sign);
}

@@ -5323,8 +5321,6 @@  vect_model_reduction_cost (loop_vec_info loop_vinfo,
if (!gimple_extract_op (orig_stmt_info->stmt, &op))
gcc_unreachable ();

-  bool emulated_mixed_dot_prod
-    = vect_is_emulated_mixed_dot_prod (loop_vinfo, stmt_info);
if (reduction_type == EXTRACT_LAST_REDUCTION)
/* No extra instructions are needed in the prologue.  The loop body
operations are costed in vectorizable_condition.  */
@@ -5359,12 +5355,8 @@  vect_model_reduction_cost (loop_vec_info loop_vinfo,
initial result of the data reduction, initial value of the index
reduction.  */
prologue_stmts = 4;
-      else if (emulated_mixed_dot_prod)
-	/* We need the initial reduction value and two invariants:
-	   one that contains the minimum signed value and one that
-	   contains half of its negative.  */
-	prologue_stmts = 3;
else
+	/* We need the initial reduction value.  */
prologue_stmts = 1;
prologue_cost += record_stmt_cost (cost_vec, prologue_stmts,
scalar_to_vec, stmt_info, 0,
@@ -7376,6 +7368,244 @@  build_vect_cond_expr (code_helper code, tree vop[3], tree mask,
}
}

+/* Given an operation with CODE in loop reduction path whose reduction PHI is
+   specified by REDUC_INFO, the operation has TYPE of scalar result, and its
+   input vectype is represented by VECTYPE_IN. The vectype of vectorized result
+   may be different from VECTYPE_IN, either in base type or vectype lanes,
+   lane-reducing operation is the case.  This function check if it is possible,
+   and how to perform partial vectorization on the operation in the context
+   of LOOP_VINFO.  */
+
+static void
+vect_reduction_use_partial_vector (loop_vec_info loop_vinfo,
+				   stmt_vec_info reduc_info,
+				   slp_tree slp_node, code_helper code,
+				   tree type, tree vectype_in)
+{
+  if (!LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
+    return;
+
+  enum vect_reduction_type reduc_type = STMT_VINFO_REDUC_TYPE (reduc_info);
+  internal_fn reduc_fn = STMT_VINFO_REDUC_FN (reduc_info);
+  internal_fn cond_fn = get_conditional_internal_fn (code, type);
+
+  if (reduc_type != FOLD_LEFT_REDUCTION
+      && !use_mask_by_cond_expr_p (code, cond_fn, vectype_in)
+      && (cond_fn == IFN_LAST
+	  || !direct_internal_fn_supported_p (cond_fn, vectype_in,
+					      OPTIMIZE_FOR_SPEED)))
+    {
+      if (dump_enabled_p ())
+	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			 "can't operate on partial vectors because"
+			 " no conditional operation is available.\n");
+      LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
+    }
+  else if (reduc_type == FOLD_LEFT_REDUCTION
+	   && reduc_fn == IFN_LAST
+	   && !expand_vec_cond_expr_p (vectype_in, truth_type_for (vectype_in),
+				       SSA_NAME))
+    {
+      if (dump_enabled_p ())
+	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			"can't operate on partial vectors because"
+			" no conditional operation is available.\n");
+      LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
+    }
+  else if (reduc_type == FOLD_LEFT_REDUCTION
+	   && internal_fn_mask_index (reduc_fn) == -1
+	   && FLOAT_TYPE_P (vectype_in)
+	   && HONOR_SIGN_DEPENDENT_ROUNDING (vectype_in))
+    {
+      if (dump_enabled_p ())
+	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			 "can't operate on partial vectors because"
+			 " signed zeros cannot be preserved.\n");
+      LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
+    }
+  else
+    {
+      vec_loop_lens *lens = &LOOP_VINFO_LENS (loop_vinfo);
+      unsigned nvectors;
+
+      if (slp_node)
+	nvectors = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
+      else
+	nvectors = vect_get_num_copies (loop_vinfo, vectype_in);
+
+	vect_record_loop_len (loop_vinfo, lens, nvectors, vectype_in, 1);
+      else
+    }
+}
+
+/* Check if STMT_INFO is a lane-reducing operation that can be vectorized in
+   the context of LOOP_VINFO, and vector cost will be recorded in COST_VEC.
+   Now there are three such kinds of operations: dot-prod/widen-sum/sad
+   (sum-of-absolute-differences).
+
+   For a lane-reducing operation, the loop reduction path that it lies in,
+   may contain normal operation, or other lane-reducing operation of different
+   input type size, an example as:
+
+     int sum = 0;
+     for (i)
+       {
+         ...
+         sum += d0[i] * d1[i];       // dot-prod <vector(16) char>
+         sum += w[i];                // widen-sum <vector(16) char>
+         sum += abs(s0[i] - s1[i]);  // sad <vector(8) short>
+         sum += n[i];                // normal <vector(4) int>
+         ...
+       }
+
+   Vectorization factor is essentially determined by operation whose input
+   vectype has the most lanes ("vector(16) char" in the example), while we
+   need to choose input vectype with the least lanes ("vector(4) int" in the
+   example) for the reduction PHI statement.  */
+
+bool
+vectorizable_lane_reducing (loop_vec_info loop_vinfo, stmt_vec_info stmt_info,
+			    slp_tree slp_node, stmt_vector_for_cost *cost_vec)
+{
+  gassign *stmt = dyn_cast <gassign *> (stmt_info->stmt);
+  if (!stmt)
+    return false;
+
+  enum tree_code code = gimple_assign_rhs_code (stmt);
+
+  if (code != DOT_PROD_EXPR && code != WIDEN_SUM_EXPR && code != SAD_EXPR)
+    return false;
+
+  tree type = TREE_TYPE (gimple_assign_lhs (stmt));
+
+  if (!INTEGRAL_TYPE_P (type) && !SCALAR_FLOAT_TYPE_P (type))
+    return false;
+
+  /* Do not try to vectorize bit-precision reductions.  */
+  if (!type_has_mode_precision_p (type))
+    return false;
+
+  tree vectype_in = NULL_TREE;
+
+  for (int i = 0; i < (int) gimple_num_ops (stmt) - 1; i++)
+    {
+      stmt_vec_info def_stmt_info;
+      slp_tree slp_op;
+      tree op;
+      tree vectype;
+      enum vect_def_type dt;
+
+      if (!vect_is_simple_use (loop_vinfo, stmt_info, slp_node, i, &op,
+			       &slp_op, &dt, &vectype, &def_stmt_info))
+	{
+	  if (dump_enabled_p ())
+	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			     "use not simple.\n");
+	  return false;
+	}
+
+      if (!vectype)
+	{
+	  vectype = get_vectype_for_scalar_type (loop_vinfo, TREE_TYPE (op),
+						 slp_op);
+	  if (!vectype)
+	    return false;
+	}
+
+      if (slp_node && !vect_maybe_update_slp_op_vectype (slp_op, vectype))
+	{
+	  if (dump_enabled_p ())
+	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			     "incompatible vector types for invariants\n");
+	  return false;
+	}
+
+      if (i == STMT_VINFO_REDUC_IDX (stmt_info))
+	continue;
+
+      /* There should be at most one cycle def in the stmt.  */
+      if (VECTORIZABLE_CYCLE_DEF (dt))
+	return false;
+
+      /* To properly compute ncopies we are interested in the widest
+	 non-reduction input type in case we're looking at a widening
+	 accumulation that we later handle in vect transformation.  */
+      if (!vectype_in
+	  || (GET_MODE_SIZE (SCALAR_TYPE_MODE (TREE_TYPE (vectype_in)))
+	      < GET_MODE_SIZE (SCALAR_TYPE_MODE (TREE_TYPE (vectype)))))
+	vectype_in = vectype;
+    }
+
+  STMT_VINFO_REDUC_VECTYPE_IN (stmt_info) = vectype_in;
+
+  stmt_vec_info reduc_info = STMT_VINFO_REDUC_DEF (vect_orig_stmt (stmt_info));
+
+  /* TODO: Support lane-reducing operation that does not directly participate
+     in loop reduction. */
+  if (!reduc_info || STMT_VINFO_REDUC_IDX (stmt_info) < 0)
+    return false;
+
+  /* Lane-reducing pattern inside any inner loop of LOOP_VINFO is not
+     recoginized.  */
+  gcc_assert (STMT_VINFO_DEF_TYPE (reduc_info) == vect_reduction_def);
+  gcc_assert (STMT_VINFO_REDUC_TYPE (reduc_info) == TREE_CODE_REDUCTION);
+
+  tree vphi_vectype_in = STMT_VINFO_REDUC_VECTYPE_IN (reduc_info);
+
+  /* To accommodate lane-reducing operations of mixed input vectypes, choose
+     input vectype with the least lanes for the reduction PHI statement, which
+     would result in the most ncopies for vectorized reduction results.  */
+  if (!vphi_vectype_in
+      || (GET_MODE_SIZE (SCALAR_TYPE_MODE (TREE_TYPE (vectype_in)))
+	  > GET_MODE_SIZE (SCALAR_TYPE_MODE (TREE_TYPE (vphi_vectype_in)))))
+    STMT_VINFO_REDUC_VECTYPE_IN (reduc_info) = vectype_in;
+
+  int ncopies_for_cost;
+
+  if (slp_node)
+    {
+      /* Now lane-reducing operations in a slp node should only come from
+	 the same loop reduction path.  */
+      gcc_assert (REDUC_GROUP_FIRST_ELEMENT (stmt_info));
+      ncopies_for_cost = 1;
+    }
+  else
+    {
+      ncopies_for_cost = vect_get_num_copies (loop_vinfo, vectype_in);
+      gcc_assert (ncopies_for_cost >= 1);
+    }
+
+  if (vect_is_emulated_mixed_dot_prod (stmt_info))
+    {
+      /* We need extra two invariants: one that contains the minimum signed
+	 value and one that contains half of its negative.  */
+      int prologue_stmts = 2;
+      unsigned cost = record_stmt_cost (cost_vec, prologue_stmts,
+					scalar_to_vec, stmt_info, 0,
+					vect_prologue);
+      if (dump_enabled_p ())
+	dump_printf (MSG_NOTE, "vectorizable_lane_reducing: "
+		     "extra prologue_cost = %d .\n", cost);
+
+      /* Three dot-products and a subtraction.  */
+      ncopies_for_cost *= 4;
+    }
+
+  record_stmt_cost (cost_vec, ncopies_for_cost, vector_stmt, stmt_info, 0,
+		    vect_body);
+
+  vect_reduction_use_partial_vector (loop_vinfo, reduc_info, slp_node, code,
+				     type, vectype_in);
+
+  STMT_VINFO_TYPE (stmt_info) = reduc_vec_info_type;
+  return true;
+}
+
/* Function vectorizable_reduction.

Check if STMT_INFO performs a reduction operation that can be vectorized.
@@ -7441,7 +7671,6 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
bool single_defuse_cycle = false;
bool nested_cycle = false;
bool double_reduc = false;
-  int vec_num;
tree cr_index_scalar_type = NULL_TREE, cr_index_vector_type = NULL_TREE;
tree cond_reduc_val = NULL_TREE;

@@ -7522,6 +7751,7 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
(gimple_bb (reduc_def_phi)->loop_father));
unsigned reduc_chain_length = 0;
bool only_slp_reduc_chain = true;
+  bool only_lane_reduc_code_p = true;
stmt_info = NULL;
slp_tree slp_for_stmt_info = slp_node ? slp_node_instance->root : NULL;
while (reduc_def != PHI_RESULT (reduc_def_phi))
@@ -7543,14 +7773,15 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
all lanes here - even though we only will vectorize from
the SLP node with live lane zero the other live lanes also
need to be identified as part of a reduction to be able
-	 to skip code generation for them.  */
+	 to skip code generation for them.  For lane-reducing operation
+	 vectorizable analysis needs the reduction PHI information.  */
if (slp_for_stmt_info)
{
for (auto s : SLP_TREE_SCALAR_STMTS (slp_for_stmt_info))
if (STMT_VINFO_LIVE_P (s))
STMT_VINFO_REDUC_DEF (vect_orig_stmt (s)) = phi_info;
}
-      else if (STMT_VINFO_LIVE_P (vdef))
+      else
STMT_VINFO_REDUC_DEF (def) = phi_info;
gimple_match_op op;
if (!gimple_extract_op (vdef->stmt, &op))
@@ -7571,9 +7802,18 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
return false;
}
}
-      else if (!stmt_info)
-	/* First non-conversion stmt.  */
-	stmt_info = vdef;
+      else
+	{
+	  /* First non-conversion stmt.  */
+	  if (!stmt_info)
+	    stmt_info = vdef;
+
+	  if (op.code != DOT_PROD_EXPR
+	      && op.code != WIDEN_SUM_EXPR
+	    only_lane_reduc_code_p = false;
+	}
+
reduc_def = op.ops[STMT_VINFO_REDUC_IDX (vdef)];
reduc_chain_length++;
if (!stmt_info && slp_node)
@@ -7647,18 +7887,6 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
if (!type_has_mode_precision_p (op.type))
return false;

-  /* For lane-reducing ops we're reducing the number of reduction PHIs
-     which means the only use of that may be in the lane-reducing operation.  */
-  if (lane_reduc_code_p
-      && reduc_chain_length != 1
-      && !only_slp_reduc_chain)
-    {
-      if (dump_enabled_p ())
-	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
-			 "lane-reducing reduction with extra stmts.\n");
-      return false;
-    }
-
/* All uses but the last are expected to be defined in the loop.
The last use is the reduction variable.  In case of nested cycle this
assumption is not true: we use reduc_index to record the index of the
@@ -7687,9 +7915,6 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
"use not simple.\n");
return false;
}
-      if (i == STMT_VINFO_REDUC_IDX (stmt_info))
-	continue;
-
/* For an IFN_COND_OP we might hit the reduction definition operand
twice (once as definition, once as else).  */
if (op.ops[i] == op.ops[STMT_VINFO_REDUC_IDX (stmt_info)])
@@ -7735,12 +7960,21 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
}
if (!vectype_in)
vectype_in = STMT_VINFO_VECTYPE (phi_info);
-  STMT_VINFO_REDUC_VECTYPE_IN (reduc_info) = vectype_in;

-  enum vect_reduction_type v_reduc_type = STMT_VINFO_REDUC_TYPE (phi_info);
-  STMT_VINFO_REDUC_TYPE (reduc_info) = v_reduc_type;
+  /* If there is a normal (non-lane-reducing) operation in the loop reduction
+     path, to ensure there will be enough copies to hold vectorized results of
+     the operation, we need set the input vectype of the reduction PHI to be
+     same as the reduction output vectype somewhere, here is a suitable place.
+     Otherwise the input vectype is set to the one with the least lanes, which
+     can only be determined in vectorizable analysis routine of lane-reducing
+     operation.  */
+  if (!only_lane_reduc_code_p)
+    STMT_VINFO_REDUC_VECTYPE_IN (reduc_info) = STMT_VINFO_VECTYPE (phi_info);
+
+  enum vect_reduction_type reduction_type = STMT_VINFO_REDUC_TYPE (phi_info);
+  STMT_VINFO_REDUC_TYPE (reduc_info) = reduction_type;
/* If we have a condition reduction, see if we can simplify it further.  */
-  if (v_reduc_type == COND_REDUCTION)
+  if (reduction_type == COND_REDUCTION)
{
if (slp_node)
return false;
@@ -7906,8 +8140,8 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
}

STMT_VINFO_REDUC_CODE (reduc_info) = orig_code;
+  reduction_type = STMT_VINFO_REDUC_TYPE (reduc_info);

-  vect_reduction_type reduction_type = STMT_VINFO_REDUC_TYPE (reduc_info);
if (reduction_type == TREE_CODE_REDUCTION)
{
/* Check whether it's ok to change the order of the computation.
@@ -8181,14 +8415,11 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
&& loop_vinfo->suggested_unroll_factor == 1)
single_defuse_cycle = true;

-  if (single_defuse_cycle || lane_reduc_code_p)
+  if (single_defuse_cycle && !lane_reduc_code_p)
{
gcc_assert (op.code != COND_EXPR);

-      /* 4. Supportable by target?  */
-      bool ok = true;
-
-      /* 4.1. check support for the operation in the loop
+      /* 4. check support for the operation in the loop

This isn't necessary for the lane reduction codes, since they
can only be produced by pattern matching, and it's up to the
@@ -8197,14 +8428,13 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
mixed-sign dot-products can be implemented using signed
dot-products.  */
machine_mode vec_mode = TYPE_MODE (vectype_in);
-      if (!lane_reduc_code_p
-	  && !directly_supported_p (op.code, vectype_in, optab_vector))
+      if (!directly_supported_p (op.code, vectype_in, optab_vector))
{
if (dump_enabled_p ())
dump_printf (MSG_NOTE, "op not supported by target.\n");
if (maybe_ne (GET_MODE_SIZE (vec_mode), UNITS_PER_WORD)
|| !vect_can_vectorize_without_simd_p (op.code))
-	    ok = false;
+	    single_defuse_cycle = false;
else
if (dump_enabled_p ())
dump_printf (MSG_NOTE, "proceeding using word mode.\n");
@@ -8217,35 +8447,12 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
dump_printf (MSG_NOTE, "using word mode not possible.\n");
return false;
}
-
-      /* lane-reducing operations have to go through vect_transform_reduction.
-         For the other cases try without the single cycle optimization.  */
-      if (!ok)
-	{
-	  if (lane_reduc_code_p)
-	    return false;
-	  else
-	    single_defuse_cycle = false;
-	}
}
STMT_VINFO_FORCE_SINGLE_CYCLE (reduc_info) = single_defuse_cycle;

-  /* If the reduction stmt is one of the patterns that have lane
-     reduction embedded we cannot handle the case of ! single_defuse_cycle.  */
-  if ((ncopies > 1 && ! single_defuse_cycle)
-      && lane_reduc_code_p)
-    {
-      if (dump_enabled_p ())
-	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
-			 "multi def-use cycle not possible for lane-reducing "
-			 "reduction operation\n");
-      return false;
-    }
-
-  if (slp_node
-      && !(!single_defuse_cycle
-	   && !lane_reduc_code_p
-	   && reduction_type != FOLD_LEFT_REDUCTION))
+  /* Reduction type of lane-reducing operation is TREE_CODE_REDUCTION, the
+     below processing will be done in its own vectorizable function.  */
+  if (slp_node && reduction_type == FOLD_LEFT_REDUCTION)
for (i = 0; i < (int) op.num_ops; i++)
if (!vect_maybe_update_slp_op_vectype (slp_op[i], vectype_op[i]))
{
@@ -8255,36 +8462,24 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
return false;
}

-  if (slp_node)
-    vec_num = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
-  else
-    vec_num = 1;
-
vect_model_reduction_cost (loop_vinfo, stmt_info, reduc_fn,
reduction_type, ncopies, cost_vec);
/* Cost the reduction op inside the loop if transformed via
-     vect_transform_reduction.  Otherwise this is costed by the
-     separate vectorizable_* routines.  */
-  if (single_defuse_cycle || lane_reduc_code_p)
-    {
-      int factor = 1;
-      if (vect_is_emulated_mixed_dot_prod (loop_vinfo, stmt_info))
-	/* Three dot-products and a subtraction.  */
-	factor = 4;
-      record_stmt_cost (cost_vec, ncopies * factor, vector_stmt,
-			stmt_info, 0, vect_body);
-    }
+     vect_transform_reduction for non-lane-reducing operation.  Otherwise
+     this is costed by the separate vectorizable_* routines.  */
+  if (single_defuse_cycle && !lane_reduc_code_p)
+    record_stmt_cost (cost_vec, ncopies, vector_stmt, stmt_info, 0, vect_body);

if (dump_enabled_p ()
&& reduction_type == FOLD_LEFT_REDUCTION)
dump_printf_loc (MSG_NOTE, vect_location,
"using an in-order (fold-left) reduction.\n");
STMT_VINFO_TYPE (orig_stmt_of_analysis) = cycle_phi_info_type;
-  /* All but single defuse-cycle optimized, lane-reducing and fold-left
-     reductions go through their own vectorizable_* routines.  */
-  if (!single_defuse_cycle
-      && !lane_reduc_code_p
-      && reduction_type != FOLD_LEFT_REDUCTION)
+
+  /* All but single defuse-cycle optimized and fold-left reductions go
+     through their own vectorizable_* routines.  */
+  if ((!single_defuse_cycle && reduction_type != FOLD_LEFT_REDUCTION)
+      || lane_reduc_code_p)
{
stmt_vec_info tem
= vect_stmt_to_vectorize (STMT_VINFO_REDUC_DEF (phi_info));
@@ -8296,60 +8491,10 @@  vectorizable_reduction (loop_vec_info loop_vinfo,
STMT_VINFO_DEF_TYPE (vect_orig_stmt (tem)) = vect_internal_def;
STMT_VINFO_DEF_TYPE (tem) = vect_internal_def;
}
-  else if (loop_vinfo && LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
-    {
-      vec_loop_lens *lens = &LOOP_VINFO_LENS (loop_vinfo);
-      internal_fn cond_fn = get_conditional_internal_fn (op.code, op.type);
-
-      if (reduction_type != FOLD_LEFT_REDUCTION
-	  && !use_mask_by_cond_expr_p (op.code, cond_fn, vectype_in)
-	  && (cond_fn == IFN_LAST
-	      || !direct_internal_fn_supported_p (cond_fn, vectype_in,
-						  OPTIMIZE_FOR_SPEED)))
-	{
-	  if (dump_enabled_p ())
-	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
-			     "can't operate on partial vectors because"
-			     " no conditional operation is available.\n");
-	  LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
-	}
-      else if (reduction_type == FOLD_LEFT_REDUCTION
-	       && reduc_fn == IFN_LAST
-	       && !expand_vec_cond_expr_p (vectype_in,
-					   truth_type_for (vectype_in),
-					   SSA_NAME))
-	{
-	  if (dump_enabled_p ())
-	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
-			     "can't operate on partial vectors because"
-			     " no conditional operation is available.\n");
-	  LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
-	}
-      else if (reduction_type == FOLD_LEFT_REDUCTION
-	       && internal_fn_mask_index (reduc_fn) == -1
-	       && FLOAT_TYPE_P (vectype_in)
-	       && HONOR_SIGN_DEPENDENT_ROUNDING (vectype_in))
-	{
-	  if (dump_enabled_p ())
-	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
-			     "can't operate on partial vectors because"
-			     " signed zeros cannot be preserved.\n");
-	  LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
-	}
-      else
-	{
+  else
+    vect_reduction_use_partial_vector (loop_vinfo, reduc_info, slp_node,
+				       op.code, op.type, vectype_in);

-	    vect_record_loop_len (loop_vinfo, lens, ncopies * vec_num,
-				  vectype_in, 1);
-	  else
-				   vectype_in, NULL);
-	}
-    }
return true;
}

@@ -8440,6 +8585,7 @@  vect_transform_reduction (loop_vec_info loop_vinfo,
class loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
int i;
int ncopies;
+  int stmt_ncopies;
int vec_num;

stmt_vec_info reduc_info = info_for_reduction (loop_vinfo, stmt_info);
@@ -8463,15 +8609,28 @@  vect_transform_reduction (loop_vec_info loop_vinfo,
gphi *reduc_def_phi = as_a <gphi *> (phi_info->stmt);
int reduc_index = STMT_VINFO_REDUC_IDX (stmt_info);
tree vectype_in = STMT_VINFO_REDUC_VECTYPE_IN (reduc_info);
+  tree stmt_vectype_in = STMT_VINFO_REDUC_VECTYPE_IN (stmt_info);
+
+  /* Get input vectypes from the reduction PHI and the statement to be
+     transformed, these two vectypes may have different lanes when
+     lane-reducing operation is present.  */
+  if (!vectype_in)
+    vectype_in = STMT_VINFO_REDUC_VECTYPE (reduc_info);
+
+  if (!stmt_vectype_in)
+    stmt_vectype_in = STMT_VINFO_VECTYPE (stmt_info);

if (slp_node)
{
ncopies = 1;
+      stmt_ncopies = 1;
vec_num = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
}
else
{
ncopies = vect_get_num_copies (loop_vinfo, vectype_in);
+      stmt_ncopies = vect_get_num_copies (loop_vinfo, stmt_vectype_in);
+      gcc_assert (stmt_ncopies >= 1 && stmt_ncopies <= ncopies);
vec_num = 1;
}

@@ -8480,14 +8639,10 @@  vect_transform_reduction (loop_vec_info loop_vinfo,

vec_loop_lens *lens = &LOOP_VINFO_LENS (loop_vinfo);
-
+						    stmt_vectype_in);
/* Transform.  */
-  tree new_temp = NULL_TREE;
-  auto_vec<tree> vec_oprnds0;
-  auto_vec<tree> vec_oprnds1;
-  auto_vec<tree> vec_oprnds2;
-  tree def0;
+  auto_vec<tree> vec_oprnds[3];

if (dump_enabled_p ())
dump_printf_loc (MSG_NOTE, vect_location, "transform reduction.\n");
@@ -8510,8 +8665,6 @@  vect_transform_reduction (loop_vec_info loop_vinfo,
== op.ops[internal_fn_else_index ((internal_fn) code)]));
}

-
vect_reduction_type reduction_type = STMT_VINFO_REDUC_TYPE (reduc_info);
if (reduction_type == FOLD_LEFT_REDUCTION)
{
@@ -8519,7 +8672,7 @@  vect_transform_reduction (loop_vec_info loop_vinfo,
gcc_assert (code.is_tree_code () || cond_fn_p);
return vectorize_fold_left_reduction
(loop_vinfo, stmt_info, gsi, vec_stmt, slp_node, reduc_def_phi,
-	   code, reduc_fn, op.ops, op.num_ops, vectype_in,
+	   code, reduc_fn, op.ops, op.num_ops, stmt_vectype_in,
}

@@ -8533,55 +8686,160 @@  vect_transform_reduction (loop_vec_info loop_vinfo,
tree scalar_dest = gimple_get_lhs (stmt_info->stmt);
tree vec_dest = vect_create_destination_var (scalar_dest, vectype_out);

-  /* Get NCOPIES vector definitions for all operands except the reduction
-     definition.  */
-  if (!cond_fn_p)
+  gcc_assert (reduc_index < 3);
+
+  if (slp_node)
{
-      vect_get_vec_defs (loop_vinfo, stmt_info, slp_node, ncopies,
-			 single_defuse_cycle && reduc_index == 0
-			 ? NULL_TREE : op.ops[0], &vec_oprnds0,
-			 single_defuse_cycle && reduc_index == 1
-			 ? NULL_TREE : op.ops[1], &vec_oprnds1,
-			 op.num_ops == 3
-			 && !(single_defuse_cycle && reduc_index == 2)
-			 ? op.ops[2] : NULL_TREE, &vec_oprnds2);
+      gcc_assert (!single_defuse_cycle && op.num_ops <= 3);
+
+      for (i = 0; i < (int) op.num_ops; i++)
+	vect_get_slp_defs (SLP_TREE_CHILDREN (slp_node)[i], &vec_oprnds[i]);
}
else
{
-      /* For a conditional operation pass the truth type as mask
-	 vectype.  */
-      gcc_assert (single_defuse_cycle
-		  && (reduc_index == 1 || reduc_index == 2));
-      vect_get_vec_defs (loop_vinfo, stmt_info, slp_node, ncopies,
-			 op.ops[0], truth_type_for (vectype_in), &vec_oprnds0,
-			 reduc_index == 1 ? NULL_TREE : op.ops[1],
-			 NULL_TREE, &vec_oprnds1,
-			 reduc_index == 2 ? NULL_TREE : op.ops[2],
-			 NULL_TREE, &vec_oprnds2);
-    }
+      int result_pos = 0;
+
+      /* The input vectype of the reduction PHI determines copies of
+	 vectorized def-use cycles, which might be more than effective copies
+	 of vectorized lane-reducing reduction statements.  This could be
+	 complemented by generating extra trivial pass-through copies.  For
+	 example:
+
+	   int sum = 0;
+	   for (i)
+	     {
+	       sum += d0[i] * d1[i];      // dot-prod <vector(16) char>
+	       sum += abs(s0[i] - s1[i]); // sad <vector(8) short>
+	       sum += n[i];               // normal <vector(4) int>
+	     }
+
+	 The vector size is 128-bit，vectorization factor is 16.  Reduction
+	 statements would be transformed as:
+
+	   vector<4> int sum_v0 = { 0, 0, 0, 0 };
+	   vector<4> int sum_v1 = { 0, 0, 0, 0 };
+	   vector<4> int sum_v2 = { 0, 0, 0, 0 };
+	   vector<4> int sum_v3 = { 0, 0, 0, 0 };
+
+	   for (i / 16)
+	     {
+	       sum_v0 = DOT_PROD (d0_v0[i: 0 ~ 15], d1_v0[i: 0 ~ 15], sum_v0);
+	       sum_v1 = sum_v1;  // copy
+	       sum_v2 = sum_v2;  // copy
+	       sum_v3 = sum_v3;  // copy
+
+	       sum_v0 = sum_v0;  // copy
+	       sum_v1 = SAD (s0_v1[i: 0 ~ 7 ], s1_v1[i: 0 ~ 7 ], sum_v1);
+	       sum_v2 = SAD (s0_v2[i: 8 ~ 15], s1_v2[i: 8 ~ 15], sum_v2);
+	       sum_v3 = sum_v3;  // copy
+
+	       sum_v0 += n_v0[i: 0  ~ 3 ];
+	       sum_v1 += n_v1[i: 4  ~ 7 ];
+	       sum_v2 += n_v2[i: 8  ~ 11];
+	       sum_v3 += n_v3[i: 12 ~ 15];
+	     }
+
+	 Moreover, for a higher instruction parallelism in final vectorized
+	 loop, it is considered to make those effective vectorized
+	 lane-reducing statements be distributed evenly among all def-use
+	 cycles. In the above example, SADs are generated into other cycles
+	 rather than that of DOT_PROD.  */
+
+      if (stmt_ncopies < ncopies)
+	{
+	  gcc_assert (code == DOT_PROD_EXPR || code == WIDEN_SUM_EXPR
+	  result_pos = reduc_info->reduc_result_pos;
+	  reduc_info->reduc_result_pos = (result_pos + stmt_ncopies) % ncopies;
+	  gcc_assert (result_pos >= 0 && result_pos < ncopies);
+	}
+
+      for (i = 0; i < MIN (3, (int) op.num_ops); i++)
+	{
+	  tree vectype = NULL_TREE;
+	  int used_ncopies = ncopies;
+
+	  if (cond_fn_p && i == 0)
+	    {
+	      /* For a conditional operation pass the truth type as mask
+		 vectype.  */
+	      gcc_assert (single_defuse_cycle && reduc_index > 0);
+	      vectype = truth_type_for (vectype_in);
+	    }

-  /* For single def-use cycles get one copy of the vectorized reduction
-     definition.  */
-  if (single_defuse_cycle)
-    {
-      gcc_assert (!slp_node);
-      vect_get_vec_defs_for_operand (loop_vinfo, stmt_info, 1,
-				     op.ops[reduc_index],
-				     reduc_index == 0 ? &vec_oprnds0
-				     : (reduc_index == 1 ? &vec_oprnds1
-					: &vec_oprnds2));
+	  if (i != reduc_index)
+	    {
+	      /* For non-reduction operand, deduce effictive copies that are
+		 involved in vectorized def-use cycles based on the input
+		 vectype of the reduction statement.  */
+	      used_ncopies = stmt_ncopies;
+	    }
+	  else if (single_defuse_cycle)
+	    {
+	      /* For single def-use cycles get one copy of the vectorized
+		 reduction definition.  */
+	      used_ncopies = 1;
+	    }
+
+	  vect_get_vec_defs_for_operand (loop_vinfo, stmt_info, used_ncopies,
+					 op.ops[i], &vec_oprnds[i], vectype);
+
+	  if (used_ncopies < ncopies)
+	    {
+	      vec_oprnds[i].safe_grow_cleared (ncopies);
+
+	      /* Find suitable def-use cycles to generate vectorized
+		 statements into, and reorder operands based on the
+		 selection.  */
+	      if (i != reduc_index && result_pos)
+		{
+		  int count = ncopies - used_ncopies;
+		  int start = result_pos - count;
+
+		  if (start < 0)
+		    {
+		      count = result_pos;
+		      start = 0;
+		    }
+
+		  for (int j = used_ncopies - 1; j >= start; j--)
+		    {
+		      std::swap (vec_oprnds[i][j], vec_oprnds[i][j + count]);
+		      gcc_assert (!vec_oprnds[i][j]);
+		    }
+		}
+	    }
+	}
}

-  bool emulated_mixed_dot_prod
-    = vect_is_emulated_mixed_dot_prod (loop_vinfo, stmt_info);
-  FOR_EACH_VEC_ELT (vec_oprnds0, i, def0)
+  bool emulated_mixed_dot_prod = vect_is_emulated_mixed_dot_prod (stmt_info);
+  tree def0;
+
+  FOR_EACH_VEC_ELT (vec_oprnds[0], i, def0)
{
gimple *new_stmt;
-      tree vop[3] = { def0, vec_oprnds1[i], NULL_TREE };
+      tree new_temp = NULL_TREE;
+      tree vop[3] = { def0, vec_oprnds[1][i], NULL_TREE };
+
+      if (!vop[0] || !vop[1])
+	{
+	  tree reduc_vop = vec_oprnds[reduc_index][i];
+
+	  /* Insert trivial copy if no need to generate vectorized
+	     statement.  */
+	  gcc_assert (reduc_vop && stmt_ncopies < ncopies);
+
+	  new_stmt = gimple_build_assign (vec_dest, reduc_vop);
+	  new_temp = make_ssa_name (vec_dest, new_stmt);
+	  gimple_set_lhs (new_stmt, new_temp);
+	  vect_finish_stmt_generation (loop_vinfo, stmt_info, new_stmt, gsi);
+	}
{
-	  /* No conditional ifns have been defined for dot-product yet.  */
-	  gcc_assert (code != DOT_PROD_EXPR);
+	  /* No conditional ifns have been defined for dot-product and sad
+	     yet.  */
+	  gcc_assert (code != DOT_PROD_EXPR && code != SAD_EXPR);

/* Make sure that the reduction accumulator is vop[0].  */
if (reduc_index == 1)
@@ -8590,7 +8848,8 @@  vect_transform_reduction (loop_vec_info loop_vinfo,
std::swap (vop[0], vop[1]);
}
-					  vec_num * ncopies, vectype_in, i);
+					  vec_num * stmt_ncopies,
+					  stmt_vectype_in, i);
gcall *call = gimple_build_call_internal (cond_fn, 4, mask,
vop[0], vop[1], vop[0]);
new_temp = make_ssa_name (vec_dest, call);
@@ -8602,12 +8861,13 @@  vect_transform_reduction (loop_vec_info loop_vinfo,
else
{
if (op.num_ops >= 3)
-	    vop[2] = vec_oprnds2[i];
+	    vop[2] = vec_oprnds[2][i];

{
-					      vec_num * ncopies, vectype_in, i);
+					      vec_num * stmt_ncopies,
+					      stmt_vectype_in, i);
}

@@ -8634,16 +8894,8 @@  vect_transform_reduction (loop_vec_info loop_vinfo,

if (slp_node)
slp_node->push_vec_def (new_stmt);
-      else if (single_defuse_cycle
-	       && i < ncopies - 1)
-	{
-	  if (reduc_index == 0)
-	    vec_oprnds0.safe_push (gimple_get_lhs (new_stmt));
-	  else if (reduc_index == 1)
-	    vec_oprnds1.safe_push (gimple_get_lhs (new_stmt));
-	  else if (reduc_index == 2)
-	    vec_oprnds2.safe_push (gimple_get_lhs (new_stmt));
-	}
+      else if (single_defuse_cycle && i < ncopies - 1)
+	vec_oprnds[reduc_index][i + 1] = gimple_get_lhs (new_stmt);
else
STMT_VINFO_VEC_STMTS (stmt_info).safe_push (new_stmt);
}
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index f8d8636b139..15331ca87f2 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -12093,11 +12093,20 @@  vectorizable_condition (vec_info *vinfo,
vect_reduction_type reduction_type = TREE_CODE_REDUCTION;
bool for_reduction
= STMT_VINFO_REDUC_DEF (vect_orig_stmt (stmt_info)) != NULL;
+  if (for_reduction)
+    {
+      reduc_info = info_for_reduction (vinfo, stmt_info);
+      if (STMT_VINFO_REDUC_DEF (reduc_info) != vect_orig_stmt (stmt_info))
+	{
+	  for_reduction = false;
+	  reduc_info = NULL;
+	}
+    }
+
if (for_reduction)
{
if (slp_node)
return false;
-      reduc_info = info_for_reduction (vinfo, stmt_info);
reduction_type = STMT_VINFO_REDUC_TYPE (reduc_info);
reduc_index = STMT_VINFO_REDUC_IDX (stmt_info);
gcc_assert (reduction_type != EXTRACT_LAST_REDUCTION
@@ -13273,6 +13282,8 @@  vect_analyze_stmt (vec_info *vinfo,
NULL, NULL, node, cost_vec)
|| vectorizable_load (vinfo, stmt_info, NULL, NULL, node, cost_vec)
|| vectorizable_store (vinfo, stmt_info, NULL, NULL, node, cost_vec)
+	  || vectorizable_lane_reducing (as_a <loop_vec_info> (vinfo),
+					 stmt_info, node, cost_vec)
|| vectorizable_reduction (as_a <loop_vec_info> (vinfo), stmt_info,
node, node_instance, cost_vec)
|| vectorizable_induction (as_a <loop_vec_info> (vinfo), stmt_info,
diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index db44d730b70..a923e1cd657 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -1399,6 +1399,12 @@  public:
/* The vector type for performing the actual reduction.  */
tree reduc_vectype;

+  /* For loop reduction with multiple vectorized results (ncopies > 1), a
+     lane-reducing operation participating in it may not use all of those
+     results, this field specifies result index starting from which any
+     following land-reducing operation would be assigned to.  */
+  int reduc_result_pos;
+
/* If IS_REDUC_INFO is true and if the vector code is performing
N scalar reductions in parallel, this variable gives the initial
scalar values of those N reductions.  */
@@ -2430,6 +2436,8 @@  extern loop_vec_info vect_create_loop_vinfo (class loop *, vec_info_shared *,
extern bool vectorizable_live_operation (vec_info *, stmt_vec_info,
slp_tree, slp_instance, int,
bool, stmt_vector_for_cost *);
+extern bool vectorizable_lane_reducing (loop_vec_info, stmt_vec_info,
+					slp_tree, stmt_vector_for_cost *);
extern bool vectorizable_reduction (loop_vec_info, stmt_vec_info,
slp_tree, slp_instance,
stmt_vector_for_cost *);
--
2.17.1

```