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* [PATCH 7/8] vect: Support multiple lane-reducing operations for loop reduction [PR114440]
@ 2024-06-16  7:31 Feng Xue OS
  2024-06-20  5:59 ` Feng Xue OS
  2024-06-20 12:26 ` Richard Biener
  0 siblings, 2 replies; 9+ messages in thread
From: Feng Xue OS @ 2024-06-16  7:31 UTC (permalink / raw)
  To: Richard Biener; +Cc: gcc-patches

[-- Attachment #1: Type: text/plain, Size: 40921 bytes --]

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.

Actually, to allow multiple arbitrary 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 trivial 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) 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 = WIDEN_SUM (w_v0[i: 0 ~ 15], sum_v0);
       sum_v1 = sum_v1;  // copy
       sum_v2 = sum_v2;  // copy
       sum_v3 = sum_v3;  // copy

       sum_v0 = SAD (s0_v0[i: 0 ~ 7 ], s1_v0[i: 0 ~ 7 ], sum_v0);
       sum_v1 = SAD (s0_v1[i: 8 ~ 15], s1_v1[i: 8 ~ 15], sum_v1);
       sum_v2 = sum_v2;  // copy
       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];
     }

Thanks,
Feng

---
gcc/
	PR tree-optimization/114440
	* tree-vectorizer.h (vectorizable_lane_reducing): New function
	declaration.
	* tree-vect-stmts.cc (vect_analyze_stmt): Call new function
	vectorizable_lane_reducing to analyze lane-reducing operation.
	* tree-vect-loop.cc (vect_model_reduction_cost): Remove cost computation
	code related to	emulated_mixed_dot_prod.
	(vect_reduction_update_partial_vector_usage): Compute ncopies as the
	original means for single-lane slp node.
	(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.
	(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-chain-dot-slp-1.c
	* gcc.dg/vect/vect-reduc-chain-dot-slp-2.c
	* gcc.dg/vect/vect-reduc-chain-dot-slp-3.c
	* gcc.dg/vect/vect-reduc-chain-dot-slp-4.c
	* gcc.dg/vect/vect-reduc-dot-slp-1.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-chain-dot-slp-1.c  |  95 +++++
 .../gcc.dg/vect/vect-reduc-chain-dot-slp-2.c  |  67 ++++
 .../gcc.dg/vect/vect-reduc-chain-dot-slp-3.c  |  79 +++++
 .../gcc.dg/vect/vect-reduc-chain-dot-slp-4.c  |  63 ++++
 .../gcc.dg/vect/vect-reduc-dot-slp-1.c        |  35 ++
 gcc/tree-vect-loop.cc                         | 324 ++++++++++++++----
 gcc/tree-vect-stmts.cc                        |   2 +
 gcc/tree-vectorizer.h                         |   2 +
 11 files changed, 802 insertions(+), 70 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-chain-dot-slp-1.c
 create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-2.c
 create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-3.c
 create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-4.c
 create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-1.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-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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-chain-dot-slp-1.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-1.c
new file mode 100644
index 00000000000..c2831fbcc8e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-1.c
@@ -0,0 +1,95 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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"
+
+#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-chain-dot-slp-2.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-2.c
new file mode 100644
index 00000000000..4114264a364
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-2.c
@@ -0,0 +1,67 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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"
+
+#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 n)
+{
+  for (int i = 0; i < n; i++)
+    {
+      res += a[5 * i + 0] * b[5 * i + 0];
+      res += a[5 * i + 1] * b[5 * i + 1];
+      res += a[5 * i + 2] * b[5 * i + 2];
+      res += a[5 * i + 3] * b[5 * i + 3];
+      res += a[5 * i + 4] * b[5 * i + 4];
+    }
+
+  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 n = 18;
+
+  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[5 * i + 0] * b[5 * i + 0];
+      expected += a[5 * i + 1] * b[5 * i + 1];
+      expected += a[5 * i + 2] * b[5 * i + 2];
+      expected += a[5 * i + 3] * b[5 * i + 3];
+      expected += a[5 * i + 4] * b[5 * i + 4];
+    }
+
+  if (f (0x12345, a, b, 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" 5 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-3.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-3.c
new file mode 100644
index 00000000000..2cdecc36d16
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-3.c
@@ -0,0 +1,79 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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"
+
+#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/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-4.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-4.c
new file mode 100644
index 00000000000..32c0f30c77b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-4.c
@@ -0,0 +1,63 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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"
+
+#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 n)
+{
+  for (int i = 0; i < n; i++)
+    {
+      res += a[3 * i + 0] * b[3 * i + 0];
+      res += a[3 * i + 1] * b[3 * i + 1];
+      res += a[3 * i + 2] * b[3 * i + 2];
+    }
+
+  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 n = 18;
+
+  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[3 * i + 0] * b[3 * i + 0];
+      expected += a[3 * i + 1] * b[3 * i + 1];
+      expected += a[3 * i + 2] * b[3 * i + 2];
+    }
+
+  if (f (0x12345, a, b, 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" 3 "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..e17d6291f75
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-1.c
@@ -0,0 +1,35 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-do compile } */
+/* { dg-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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"
+
+#ifndef SIGNEDNESS_1
+#define SIGNEDNESS_1 signed
+#define SIGNEDNESS_2 signed
+#endif
+
+SIGNEDNESS_1 int __attribute__ ((noipa))
+f (SIGNEDNESS_1 int res0,
+   SIGNEDNESS_1 int res1,
+   SIGNEDNESS_1 int res2,
+   SIGNEDNESS_1 int res3,
+   SIGNEDNESS_2 short *a,
+   SIGNEDNESS_2 short *b)
+{
+  for (int i = 0; i < 64; i += 4)
+    {
+      res0 += a[i + 0] * b[i + 0];
+      res1 += a[i + 1] * b[i + 1];
+      res2 += a[i + 2] * b[i + 2];
+      res3 += a[i + 3] * b[i + 3];
+    }
+
+  return res0 ^ res1 ^ res2 ^ res3;
+}
+
+/* { dg-final { scan-tree-dump "vect_recog_dot_prod_pattern: detected" "vect" } } */
+/* { dg-final { scan-tree-dump-not "vectorizing stmts using SLP" "vect" } } */
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index e0561feddce..6d91665a341 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -5324,8 +5324,6 @@ 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 (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.  */
@@ -5360,12 +5358,8 @@ 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,
@@ -7466,7 +7460,7 @@ vect_reduction_update_partial_vector_usage (loop_vec_info loop_vinfo,
       vec_loop_lens *lens = &LOOP_VINFO_LENS (loop_vinfo);
       unsigned nvectors;
 
-      if (slp_node)
+      if (slp_node && SLP_TREE_LANES (slp_node) > 1)
 	nvectors = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
       else
 	nvectors = vect_get_num_copies (loop_vinfo, vectype_in);
@@ -7478,6 +7472,152 @@ vect_reduction_update_partial_vector_usage (loop_vec_info loop_vinfo,
     }
 }
 
+/* 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)
+{
+  gimple *stmt = stmt_info->stmt;
+
+  if (!lane_reducing_stmt_p (stmt))
+    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;
+
+  if (!slp_node)
+    return false;
+
+  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 (!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;
+    }
+
+  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 vectype_in = STMT_VINFO_REDUC_VECTYPE_IN (stmt_info);
+  int ncopies_for_cost;
+
+  if (SLP_TREE_LANES (slp_node) > 1)
+    {
+      /* Now lane-reducing operations in a non-single-lane 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);
+
+  if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
+    {
+      enum tree_code code = gimple_assign_rhs_code (stmt);
+      vect_reduction_update_partial_vector_usage (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.
@@ -7804,18 +7944,6 @@ 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_reducing
-      && 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;
-    }
-
   /* Lane-reducing ops also never can be used in a SLP reduction group
      since we'll mix lanes belonging to different reductions.  But it's
      OK to use them in a reduction chain or when the reduction group
@@ -8354,14 +8482,11 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
       && loop_vinfo->suggested_unroll_factor == 1)
     single_defuse_cycle = true;
 
-  if (single_defuse_cycle || lane_reducing)
+  if (single_defuse_cycle && !lane_reducing)
     {
       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
@@ -8370,14 +8495,13 @@ 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_reducing
-	  && !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");
@@ -8390,16 +8514,6 @@ 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_reducing)
-	    return false;
-	  else
-	    single_defuse_cycle = false;
-	}
     }
   if (dump_enabled_p () && single_defuse_cycle)
     dump_printf_loc (MSG_NOTE, vect_location,
@@ -8407,22 +8521,14 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
 		     "multiple vectors to one in the loop body\n");
   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_reducing)
-    {
-      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;
-    }
+  /* For lane-reducing operation, the below processing related to single
+     defuse-cycle will be done in its own vectorizable function.  One more
+     thing to note is that the operation must not be involved in fold-left
+     reduction.  */
+  single_defuse_cycle &= !lane_reducing;
 
   if (slp_node
-      && !(!single_defuse_cycle
-	   && !lane_reducing
-	   && reduction_type != FOLD_LEFT_REDUCTION))
+      && (single_defuse_cycle || 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]))
 	{
@@ -8435,28 +8541,20 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
   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_reducing)
-    {
-      int factor = 1;
-      if (vect_is_emulated_mixed_dot_prod (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)
+    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_reducing
-      && 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)
     {
       stmt_vec_info tem
 	= vect_stmt_to_vectorize (STMT_VINFO_REDUC_DEF (phi_info));
@@ -8646,6 +8744,15 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
   bool lane_reducing = lane_reducing_op_p (code);
   gcc_assert (single_defuse_cycle || lane_reducing);
 
+  if (lane_reducing)
+    {
+      /* The last operand of lane-reducing op is for reduction.  */
+      gcc_assert (reduc_index == (int) op.num_ops - 1);
+
+      /* Now all lane-reducing ops are covered by some slp node.  */
+      gcc_assert (slp_node);
+    }
+
   /* Create the destination vector  */
   tree scalar_dest = gimple_get_lhs (stmt_info->stmt);
   tree vec_dest = vect_create_destination_var (scalar_dest, vectype_out);
@@ -8689,6 +8796,58 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
 			 reduc_index == 2 ? op.ops[2] : NULL_TREE,
 			 &vec_oprnds[2]);
     }
+  else if (lane_reducing && SLP_TREE_LANES (slp_node) == 1
+	   && vec_oprnds[0].length () < vec_oprnds[reduc_index].length ())
+    {
+      /* For lane-reducing op covered by single-lane slp node, 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 = SAD (s0_v0[i: 0 ~ 7 ], s1_v0[i: 0 ~ 7 ], sum_v0);
+	       sum_v1 = SAD (s0_v1[i: 8 ~ 15], s1_v1[i: 8 ~ 15], sum_v1);
+	       sum_v2 = sum_v2;  // copy
+	       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];
+	     }
+	*/
+      unsigned using_ncopies = vec_oprnds[0].length ();
+      unsigned reduc_ncopies = vec_oprnds[reduc_index].length ();
+
+      for (unsigned i = 0; i < op.num_ops - 1; i++)
+	{
+	  gcc_assert (vec_oprnds[i].length () == using_ncopies);
+	  vec_oprnds[i].safe_grow_cleared (reduc_ncopies);
+	}
+    }
 
   bool emulated_mixed_dot_prod = vect_is_emulated_mixed_dot_prod (stmt_info);
   unsigned num = vec_oprnds[reduc_index == 0 ? 1 : 0].length ();
@@ -8697,7 +8856,21 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
     {
       gimple *new_stmt;
       tree vop[3] = { vec_oprnds[0][i], vec_oprnds[1][i], NULL_TREE };
-      if (masked_loop_p && !mask_by_cond_expr)
+
+      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);
+
+	  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);
+	}
+      else if (masked_loop_p && !mask_by_cond_expr)
 	{
 	  /* No conditional ifns have been defined for lane-reducing op
 	     yet.  */
@@ -8726,8 +8899,19 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
 
 	  if (masked_loop_p && mask_by_cond_expr)
 	    {
+	      tree stmt_vectype_in = vectype_in;
+	      unsigned nvectors = vec_num * ncopies;
+	
+	      if (lane_reducing && SLP_TREE_LANES (slp_node) == 1)
+		{
+		  /* Input vectype of the reduction PHI may be defferent from
+		     that of lane-reducing operation.  */
+		  stmt_vectype_in = STMT_VINFO_REDUC_VECTYPE_IN (stmt_info);
+		  nvectors = vect_get_num_copies (loop_vinfo, stmt_vectype_in);
+		}
+
 	      tree mask = vect_get_loop_mask (loop_vinfo, gsi, masks,
-					      vec_num * ncopies, vectype_in, i);
+					      nvectors, stmt_vectype_in, i);
 	      build_vect_cond_expr (code, vop, mask, gsi);
 	    }
 
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index ca6052662a3..1b73ef01ade 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -13350,6 +13350,8 @@ 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 60224f4e284..94736736dcc 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -2455,6 +2455,8 @@ 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

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0007-vect-Support-multiple-lane-reducing-operations-for-l.patch --]
[-- Type: text/x-patch; name="0007-vect-Support-multiple-lane-reducing-operations-for-l.patch", Size: 40043 bytes --]

From 67045272c75c3016c33cb87f893ce4cd3a8374a0 Mon Sep 17 00:00:00 2001
From: Feng Xue <fxue@os.amperecomputing.com>
Date: Wed, 29 May 2024 17:22:36 +0800
Subject: [PATCH 7/8] vect: Support multiple lane-reducing operations for loop
 reduction [PR114440]

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.

Actually, 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) 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 = WIDEN_SUM (w_v0[i: 0 ~ 15], sum_v0);
       sum_v1 = sum_v1;  // copy
       sum_v2 = sum_v2;  // copy
       sum_v3 = sum_v3;  // copy

       sum_v0 = SAD (s0_v0[i: 0 ~ 7 ], s1_v0[i: 0 ~ 7 ], sum_v0);
       sum_v1 = SAD (s0_v1[i: 8 ~ 15], s1_v1[i: 8 ~ 15], sum_v1);
       sum_v2 = sum_v2;  // copy
       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];
     }

2024-03-22 Feng Xue <fxue@os.amperecomputing.com>

gcc/
	PR tree-optimization/114440
	* tree-vectorizer.h (vectorizable_lane_reducing): New function
	declaration.
	* tree-vect-stmts.cc (vect_analyze_stmt): Call new function
	vectorizable_lane_reducing to analyze lane-reducing operation.
	* tree-vect-loop.cc (vect_model_reduction_cost): Remove cost computation
	code related to	emulated_mixed_dot_prod.
	(vect_reduction_update_partial_vector_usage): Compute ncopies as the
	original means for single-lane slp node.
	(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.
	(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-chain-dot-slp-1.c
	* gcc.dg/vect/vect-reduc-chain-dot-slp-2.c
	* gcc.dg/vect/vect-reduc-chain-dot-slp-3.c
	* gcc.dg/vect/vect-reduc-chain-dot-slp-4.c
	* gcc.dg/vect/vect-reduc-dot-slp-1.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-chain-dot-slp-1.c  |  95 +++++
 .../gcc.dg/vect/vect-reduc-chain-dot-slp-2.c  |  67 ++++
 .../gcc.dg/vect/vect-reduc-chain-dot-slp-3.c  |  79 +++++
 .../gcc.dg/vect/vect-reduc-chain-dot-slp-4.c  |  63 ++++
 .../gcc.dg/vect/vect-reduc-dot-slp-1.c        |  35 ++
 gcc/tree-vect-loop.cc                         | 324 ++++++++++++++----
 gcc/tree-vect-stmts.cc                        |   2 +
 gcc/tree-vectorizer.h                         |   2 +
 11 files changed, 802 insertions(+), 70 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-chain-dot-slp-1.c
 create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-2.c
 create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-3.c
 create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-4.c
 create mode 100644 gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-1.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-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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-chain-dot-slp-1.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-1.c
new file mode 100644
index 00000000000..c2831fbcc8e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-1.c
@@ -0,0 +1,95 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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"
+
+#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-chain-dot-slp-2.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-2.c
new file mode 100644
index 00000000000..4114264a364
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-2.c
@@ -0,0 +1,67 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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"
+
+#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 n)
+{
+  for (int i = 0; i < n; i++)
+    {
+      res += a[5 * i + 0] * b[5 * i + 0];
+      res += a[5 * i + 1] * b[5 * i + 1];
+      res += a[5 * i + 2] * b[5 * i + 2];
+      res += a[5 * i + 3] * b[5 * i + 3];
+      res += a[5 * i + 4] * b[5 * i + 4];
+    }
+
+  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 n = 18;
+
+  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[5 * i + 0] * b[5 * i + 0];
+      expected += a[5 * i + 1] * b[5 * i + 1];
+      expected += a[5 * i + 2] * b[5 * i + 2];
+      expected += a[5 * i + 3] * b[5 * i + 3];
+      expected += a[5 * i + 4] * b[5 * i + 4];
+    }
+
+  if (f (0x12345, a, b, 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" 5 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-3.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-3.c
new file mode 100644
index 00000000000..2cdecc36d16
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-3.c
@@ -0,0 +1,79 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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"
+
+#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/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-4.c b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-4.c
new file mode 100644
index 00000000000..32c0f30c77b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-chain-dot-slp-4.c
@@ -0,0 +1,63 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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"
+
+#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 n)
+{
+  for (int i = 0; i < n; i++)
+    {
+      res += a[3 * i + 0] * b[3 * i + 0];
+      res += a[3 * i + 1] * b[3 * i + 1];
+      res += a[3 * i + 2] * b[3 * i + 2];
+    }
+
+  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 n = 18;
+
+  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[3 * i + 0] * b[3 * i + 0];
+      expected += a[3 * i + 1] * b[3 * i + 1];
+      expected += a[3 * i + 2] * b[3 * i + 2];
+    }
+
+  if (f (0x12345, a, b, 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" 3 "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..e17d6291f75
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-reduc-dot-slp-1.c
@@ -0,0 +1,35 @@
+/* Disabling epilogues until we find a better way to deal with scans.  */
+/* { dg-do compile } */
+/* { dg-additional-options "--param vect-epilogues-nomask=0" } */
+/* { 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"
+
+#ifndef SIGNEDNESS_1
+#define SIGNEDNESS_1 signed
+#define SIGNEDNESS_2 signed
+#endif
+
+SIGNEDNESS_1 int __attribute__ ((noipa))
+f (SIGNEDNESS_1 int res0,
+   SIGNEDNESS_1 int res1,
+   SIGNEDNESS_1 int res2,
+   SIGNEDNESS_1 int res3,
+   SIGNEDNESS_2 short *a,
+   SIGNEDNESS_2 short *b)
+{
+  for (int i = 0; i < 64; i += 4)
+    {
+      res0 += a[i + 0] * b[i + 0];
+      res1 += a[i + 1] * b[i + 1];
+      res2 += a[i + 2] * b[i + 2];
+      res3 += a[i + 3] * b[i + 3];
+    }
+
+  return res0 ^ res1 ^ res2 ^ res3;
+}
+
+/* { dg-final { scan-tree-dump "vect_recog_dot_prod_pattern: detected" "vect" } } */
+/* { dg-final { scan-tree-dump-not "vectorizing stmts using SLP" "vect" } } */
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index e0561feddce..6d91665a341 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -5324,8 +5324,6 @@ 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 (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.  */
@@ -5360,12 +5358,8 @@ 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,
@@ -7466,7 +7460,7 @@ vect_reduction_update_partial_vector_usage (loop_vec_info loop_vinfo,
       vec_loop_lens *lens = &LOOP_VINFO_LENS (loop_vinfo);
       unsigned nvectors;
 
-      if (slp_node)
+      if (slp_node && SLP_TREE_LANES (slp_node) > 1)
 	nvectors = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
       else
 	nvectors = vect_get_num_copies (loop_vinfo, vectype_in);
@@ -7478,6 +7472,152 @@ vect_reduction_update_partial_vector_usage (loop_vec_info loop_vinfo,
     }
 }
 
+/* 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)
+{
+  gimple *stmt = stmt_info->stmt;
+
+  if (!lane_reducing_stmt_p (stmt))
+    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;
+
+  if (!slp_node)
+    return false;
+
+  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 (!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;
+    }
+
+  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 vectype_in = STMT_VINFO_REDUC_VECTYPE_IN (stmt_info);
+  int ncopies_for_cost;
+
+  if (SLP_TREE_LANES (slp_node) > 1)
+    {
+      /* Now lane-reducing operations in a non-single-lane 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);
+
+  if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
+    {
+      enum tree_code code = gimple_assign_rhs_code (stmt);
+      vect_reduction_update_partial_vector_usage (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.
@@ -7804,18 +7944,6 @@ 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_reducing
-      && 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;
-    }
-
   /* Lane-reducing ops also never can be used in a SLP reduction group
      since we'll mix lanes belonging to different reductions.  But it's
      OK to use them in a reduction chain or when the reduction group
@@ -8354,14 +8482,11 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
       && loop_vinfo->suggested_unroll_factor == 1)
     single_defuse_cycle = true;
 
-  if (single_defuse_cycle || lane_reducing)
+  if (single_defuse_cycle && !lane_reducing)
     {
       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
@@ -8370,14 +8495,13 @@ 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_reducing
-	  && !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");
@@ -8390,16 +8514,6 @@ 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_reducing)
-	    return false;
-	  else
-	    single_defuse_cycle = false;
-	}
     }
   if (dump_enabled_p () && single_defuse_cycle)
     dump_printf_loc (MSG_NOTE, vect_location,
@@ -8407,22 +8521,14 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
 		     "multiple vectors to one in the loop body\n");
   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_reducing)
-    {
-      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;
-    }
+  /* For lane-reducing operation, the below processing related to single
+     defuse-cycle will be done in its own vectorizable function.  One more
+     thing to note is that the operation must not be involved in fold-left
+     reduction.  */
+  single_defuse_cycle &= !lane_reducing;
 
   if (slp_node
-      && !(!single_defuse_cycle
-	   && !lane_reducing
-	   && reduction_type != FOLD_LEFT_REDUCTION))
+      && (single_defuse_cycle || 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]))
 	{
@@ -8435,28 +8541,20 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
   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_reducing)
-    {
-      int factor = 1;
-      if (vect_is_emulated_mixed_dot_prod (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)
+    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_reducing
-      && 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)
     {
       stmt_vec_info tem
 	= vect_stmt_to_vectorize (STMT_VINFO_REDUC_DEF (phi_info));
@@ -8646,6 +8744,15 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
   bool lane_reducing = lane_reducing_op_p (code);
   gcc_assert (single_defuse_cycle || lane_reducing);
 
+  if (lane_reducing)
+    {
+      /* The last operand of lane-reducing op is for reduction.  */
+      gcc_assert (reduc_index == (int) op.num_ops - 1);
+
+      /* Now all lane-reducing ops are covered by some slp node.  */
+      gcc_assert (slp_node);
+    }
+
   /* Create the destination vector  */
   tree scalar_dest = gimple_get_lhs (stmt_info->stmt);
   tree vec_dest = vect_create_destination_var (scalar_dest, vectype_out);
@@ -8689,6 +8796,58 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
 			 reduc_index == 2 ? op.ops[2] : NULL_TREE,
 			 &vec_oprnds[2]);
     }
+  else if (lane_reducing && SLP_TREE_LANES (slp_node) == 1
+	   && vec_oprnds[0].length () < vec_oprnds[reduc_index].length ())
+    {
+      /* For lane-reducing op covered by single-lane slp node, 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 = SAD (s0_v0[i: 0 ~ 7 ], s1_v0[i: 0 ~ 7 ], sum_v0);
+	       sum_v1 = SAD (s0_v1[i: 8 ~ 15], s1_v1[i: 8 ~ 15], sum_v1);
+	       sum_v2 = sum_v2;  // copy
+	       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];
+	     }
+	*/
+      unsigned using_ncopies = vec_oprnds[0].length ();
+      unsigned reduc_ncopies = vec_oprnds[reduc_index].length ();
+
+      for (unsigned i = 0; i < op.num_ops - 1; i++)
+	{
+	  gcc_assert (vec_oprnds[i].length () == using_ncopies);
+	  vec_oprnds[i].safe_grow_cleared (reduc_ncopies);
+	}
+    }
 
   bool emulated_mixed_dot_prod = vect_is_emulated_mixed_dot_prod (stmt_info);
   unsigned num = vec_oprnds[reduc_index == 0 ? 1 : 0].length ();
@@ -8697,7 +8856,21 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
     {
       gimple *new_stmt;
       tree vop[3] = { vec_oprnds[0][i], vec_oprnds[1][i], NULL_TREE };
-      if (masked_loop_p && !mask_by_cond_expr)
+
+      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);
+
+	  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);
+	}
+      else if (masked_loop_p && !mask_by_cond_expr)
 	{
 	  /* No conditional ifns have been defined for lane-reducing op
 	     yet.  */
@@ -8726,8 +8899,19 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
 
 	  if (masked_loop_p && mask_by_cond_expr)
 	    {
+	      tree stmt_vectype_in = vectype_in;
+	      unsigned nvectors = vec_num * ncopies;
+	
+	      if (lane_reducing && SLP_TREE_LANES (slp_node) == 1)
+		{
+		  /* Input vectype of the reduction PHI may be defferent from
+		     that of lane-reducing operation.  */
+		  stmt_vectype_in = STMT_VINFO_REDUC_VECTYPE_IN (stmt_info);
+		  nvectors = vect_get_num_copies (loop_vinfo, stmt_vectype_in);
+		}
+
 	      tree mask = vect_get_loop_mask (loop_vinfo, gsi, masks,
-					      vec_num * ncopies, vectype_in, i);
+					      nvectors, stmt_vectype_in, i);
 	      build_vect_cond_expr (code, vop, mask, gsi);
 	    }
 
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index ca6052662a3..1b73ef01ade 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -13350,6 +13350,8 @@ 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 60224f4e284..94736736dcc 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -2455,6 +2455,8 @@ 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


^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2024-06-28 13:07 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-06-16  7:31 [PATCH 7/8] vect: Support multiple lane-reducing operations for loop reduction [PR114440] Feng Xue OS
2024-06-20  5:59 ` Feng Xue OS
2024-06-20 12:26 ` Richard Biener
2024-06-23 15:10   ` Feng Xue OS
2024-06-24 12:58     ` Richard Biener
2024-06-25  9:32       ` Feng Xue OS
2024-06-25 10:26         ` Richard Biener
2024-06-26 14:50         ` Feng Xue OS
2024-06-28 13:06           ` Richard Biener

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