re PR target/82108 (Wrong vectorized code generated for x86_64)

2017-09-06  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/82108
	* tree-vect-stmts.c (vectorizable_load): Fix pointer adjustment
	for gap in the non-permutation SLP case.

	* gcc.dg/vect/pr82108.c: New testcase.

From-SVN: r251790

gcc/ChangeLog

+2017-09-06  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/82108
+	* tree-vect-stmts.c (vectorizable_load): Fix pointer adjustment
+	for gap in the non-permutation SLP case.
+
 2017-09-06  Martin Jambor  <mjambor@suse.cz>
 
 	PR tree-optimization/82078

gcc/testsuite/ChangeLog

+2017-09-06  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/82108
+	* gcc.dg/vect/pr82108.c: New testcase.
+
 2017-09-06  Martin Jambor  <mjambor@suse.cz>
 
 	PR tree-optimization/82078

gcc/testsuite/gcc.dg/vect/pr82108.c

+/* { dg-do run } */
+/* { dg-require-effective-target vect_float } */
+
+#include "tree-vect.h"
+
+void __attribute__((noinline,noclone))
+downscale_2 (const float* src, int src_n, float* dst)
+{
+  int i;
+
+  for (i = 0; i < src_n; i += 2) {
+      const float* a = src;
+      const float* b = src + 4;
+
+      dst[0] = (a[0] + b[0]) / 2;
+      dst[1] = (a[1] + b[1]) / 2;
+      dst[2] = (a[2] + b[2]) / 2;
+      dst[3] = (a[3] + b[3]) / 2;
+
+      src += 2 * 4;
+      dst +=     4;
+  }
+}
+
+int main ()
+{
+  const float in[4 * 4] = {
+      1, 2, 3, 4,
+      5, 6, 7, 8,
+
+      1, 2, 3, 4,
+      5, 6, 7, 8
+  };
+  float out[2 * 4];
+
+  check_vect ();
+
+  downscale_2 (in, 4, out);
+
+  if (out[0] != 3 || out[1] != 4 || out[2] != 5 || out[3] != 6
+      || out[4] != 3 || out[5] != 4 || out[6] != 5 || out[7] != 6)
+    __builtin_abort ();
+  
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */

gcc/tree-vect-stmts.c

@@ -7213,7 +7213,6 @@ vectorizable_load (gimple *stmt, gimple_stmt_iterator *gsi, gimple **vec_stmt,
     {
       first_stmt = GROUP_FIRST_ELEMENT (stmt_info);
       group_size = GROUP_SIZE (vinfo_for_stmt (first_stmt));
-      int group_gap = GROUP_GAP (vinfo_for_stmt (first_stmt));
       /* For SLP vectorization we directly vectorize a subchain
          without permutation.  */
       if (slp && ! SLP_TREE_LOAD_PERMUTATION (slp_node).exists ())
@@ -7256,7 +7255,8 @@ vectorizable_load (gimple *stmt, gimple_stmt_iterator *gsi, gimple **vec_stmt,
 	  else
 	    {
 	      vec_num = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
-	      group_gap_adj = group_gap;
+	      group_gap_adj
+		= group_size - SLP_INSTANCE_GROUP_SIZE (slp_node_instance);
 	    }
     	}
       else