8.4.0: backport PR97236: fix bad use of VMAT_CONTIGUOUS

Bug: https://gcc.gnu.org/PR97236
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

2 files changed, 121 insertions, 0 deletions

diff --git a/8.4.0/gentoo/33_all_vmat-PR97236.patch b/8.4.0/gentoo/33_all_vmat-PR97236.patch
new file mode 100644
index 0000000..ee5e46c
--- /dev/null
+++ b/8.4.0/gentoo/33_all_vmat-PR97236.patch
@@ -0,0 +1,118 @@
+https://gcc.gnu.org/PR97236
+
+From de0ede7625f6c4d4bbd2caaf363032b0da80cf69 Mon Sep 17 00:00:00 2001
+From: Matthias Klose <doko@ubuntu.com>
+Date: Tue, 6 Oct 2020 13:41:37 +0200
+Subject: [PATCH] Backport fix for PR/tree-optimization/97236 - fix bad use of
+ VMAT_CONTIGUOUS
+
+This avoids using VMAT_CONTIGUOUS with single-element interleaving
+when using V1mode vectors.  Instead keep VMAT_ELEMENTWISE but
+continue to avoid load-lanes and gathers.
+
+2020-10-01  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/97236
+	* tree-vect-stmts.c (get_group_load_store_type): Keep
+	VMAT_ELEMENTWISE for single-element vectors.
+
+	* gcc.dg/vect/pr97236.c: New testcase.
+
+(cherry picked from commit 1ab88985631dd2c5a5e3b5c0dce47cf8b6ed2f82)
+---
+ gcc/testsuite/gcc.dg/vect/pr97236.c | 43 +++++++++++++++++++++++++++++
+ gcc/tree-vect-stmts.c               | 20 ++++++--------
+ 2 files changed, 52 insertions(+), 11 deletions(-)
+ create mode 100644 gcc/testsuite/gcc.dg/vect/pr97236.c
+
+diff --git a/gcc/testsuite/gcc.dg/vect/pr97236.c b/gcc/testsuite/gcc.dg/vect/pr97236.c
+new file mode 100644
+index 00000000000..9d3dc20d953
+--- /dev/null
++++ b/gcc/testsuite/gcc.dg/vect/pr97236.c
+@@ -0,0 +1,43 @@
++typedef unsigned char __uint8_t;
++typedef __uint8_t uint8_t;
++typedef struct plane_t {
++  uint8_t *p_pixels;
++  int i_lines;
++  int i_pitch;
++} plane_t;
++
++typedef struct {
++  plane_t p[5];
++} picture_t;
++
++#define N 4
++
++void __attribute__((noipa))
++picture_Clone(picture_t *picture, picture_t *res)
++{
++  for (int i = 0; i < N; i++) {
++    res->p[i].p_pixels = picture->p[i].p_pixels;
++    res->p[i].i_lines = picture->p[i].i_lines;
++    res->p[i].i_pitch = picture->p[i].i_pitch;
++  }
++}
++
++int
++main()
++{
++  picture_t aaa, bbb;
++  uint8_t pixels[10] = {1, 1, 1, 1, 1, 1, 1, 1};
++
++  for (unsigned i = 0; i < N; i++)
++    aaa.p[i].p_pixels = pixels;
++
++  picture_Clone (&aaa, &bbb);
++
++  uint8_t c = 0;
++  for (unsigned i = 0; i < N; i++)
++    c += bbb.p[i].p_pixels[0];
++
++  if (c != N)
++    __builtin_abort ();
++  return 0;
++}
+diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
+index 7472558048c..ea75c7249aa 100644
+--- a/gcc/tree-vect-stmts.c
++++ b/gcc/tree-vect-stmts.c
+@@ -2209,25 +2209,23 @@ get_group_load_store_type (gimple *stmt, tree vectype, bool slp,
+ 	  /* First cope with the degenerate case of a single-element
+ 	     vector.  */
+ 	  if (known_eq (TYPE_VECTOR_SUBPARTS (vectype), 1U))
+-	    *memory_access_type = VMAT_CONTIGUOUS;
++	    ;
+ 
+ 	  /* Otherwise try using LOAD/STORE_LANES.  */
+-	  if (*memory_access_type == VMAT_ELEMENTWISE
+-	      && (vls_type == VLS_LOAD
+-		  ? vect_load_lanes_supported (vectype, group_size, masked_p)
+-		  : vect_store_lanes_supported (vectype, group_size,
+-						masked_p)))
++	  else if (vls_type == VLS_LOAD
++		   ? vect_load_lanes_supported (vectype, group_size, masked_p)
++		   : vect_store_lanes_supported (vectype, group_size,
++						 masked_p))
+ 	    {
+ 	      *memory_access_type = VMAT_LOAD_STORE_LANES;
+ 	      overrun_p = would_overrun_p;
+ 	    }
+ 
+ 	  /* If that fails, try using permuting loads.  */
+-	  if (*memory_access_type == VMAT_ELEMENTWISE
+-	      && (vls_type == VLS_LOAD
+-		  ? vect_grouped_load_supported (vectype, single_element_p,
+-						 group_size)
+-		  : vect_grouped_store_supported (vectype, group_size)))
++	  else if (vls_type == VLS_LOAD
++		   ? vect_grouped_load_supported (vectype, single_element_p,
++						  group_size)
++		   : vect_grouped_store_supported (vectype, group_size))
+ 	    {
+ 	      *memory_access_type = VMAT_CONTIGUOUS_PERMUTE;
+ 	      overrun_p = would_overrun_p;
+-- 
+2.30.1
+
diff --git a/8.4.0/gentoo/README.history b/8.4.0/gentoo/README.history
index b922698..3997a59 100644
--- a/8.4.0/gentoo/README.history
+++ b/8.4.0/gentoo/README.history
@@ -1,3 +1,6 @@
+4		TODO
+	+ 33_all_vmat-PR97236.patch
+
 3		18 Dec 2020
 	+ 31_all_plugin-objdump.patch
 	U 11_all_extra-options.patch