[PATCH] Fix PR79824

[Richard Biener <rguenther at suse dot de>]

The following fixes too aggressive disabling of peeling for gaps for
interleaving and load-lanes (as well as fixing the test so it applies
for multi-element as well).

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2017-03-06  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/79824
	* tree-vect-stmts.c (get_group_load_store_type): Fix alignment
	check disabling peeling for gaps.

	* gcc.dg/vect/pr79824-1.c: New testcase.
	* gcc.dg/vect/pr79824-2.c: Likewise.

Index: gcc/tree-vect-stmts.c
===================================================================
--- gcc/tree-vect-stmts.c	(revision 245908)
+++ gcc/tree-vect-stmts.c	(working copy)
@@ -1731,7 +1731,7 @@ get_group_load_store_type (gimple *stmt,
   bool single_element_p = (stmt == first_stmt
 			   && !GROUP_NEXT_ELEMENT (stmt_info));
   unsigned HOST_WIDE_INT gap = GROUP_GAP (vinfo_for_stmt (first_stmt));
-  int nunits = TYPE_VECTOR_SUBPARTS (vectype);
+  unsigned nunits = TYPE_VECTOR_SUBPARTS (vectype);
 
   /* True if the vectorized statements would access beyond the last
      statement in the group.  */
@@ -1794,9 +1794,13 @@ get_group_load_store_type (gimple *stmt,
       /* If there is a gap at the end of the group then these optimizations
 	 would access excess elements in the last iteration.  */
       bool would_overrun_p = (gap != 0);
-      /* If the access is aligned an overrun is fine.  */
+      /* If the access is aligned an overrun is fine, but only if the
+         overrun is not inside an unused vector (if the gap is as large
+	 or larger than a vector).  */
       if (would_overrun_p
-	  && aligned_access_p (STMT_VINFO_DATA_REF (stmt_info)))
+	  && gap < nunits
+	  && aligned_access_p
+		(STMT_VINFO_DATA_REF (vinfo_for_stmt (first_stmt))))
 	would_overrun_p = false;
       if (!STMT_VINFO_STRIDED_P (stmt_info)
 	  && (can_overrun_p || !would_overrun_p)
Index: gcc/testsuite/gcc.dg/vect/pr79824-1.c
===================================================================
--- gcc/testsuite/gcc.dg/vect/pr79824-1.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/vect/pr79824-1.c	(working copy)
@@ -0,0 +1,46 @@
+/* { dg-require-effective-target mmap } */
+
+#include <sys/mman.h>
+#include <stdio.h>
+#include "tree-vect.h"
+
+#define COUNT 320
+#define MMAP_SIZE 0x10000
+#define ADDRESS 0x1122000000
+#define TYPE double
+
+#ifndef MAP_ANONYMOUS
+#define MAP_ANONYMOUS MAP_ANON
+#endif
+
+void __attribute__((noinline))
+foo (TYPE *__restrict a, TYPE *__restrict b)
+{
+  int n;
+
+  b = __builtin_assume_aligned (b, sizeof (TYPE) * 2);
+  a = __builtin_assume_aligned (a, sizeof (TYPE) * 2);
+  for (n = 0; n < COUNT; n++)
+    a[n] = b[n * 4];
+}
+
+int
+main (void)
+{
+  void *x;
+  size_t b_offset;
+
+  check_vect ();
+
+  x = mmap ((void *) ADDRESS, MMAP_SIZE, PROT_READ | PROT_WRITE,
+	    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  if (x == MAP_FAILED)
+    {
+      perror ("mmap");
+      return 1;
+    }
+
+  b_offset = MMAP_SIZE - (4 * COUNT - 2) * sizeof (TYPE);
+  foo ((TYPE *) x, (TYPE *) ((char *) x + b_offset));
+  return 0;
+}
Index: gcc/testsuite/gcc.dg/vect/pr79824-2.c
===================================================================
--- gcc/testsuite/gcc.dg/vect/pr79824-2.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/vect/pr79824-2.c	(working copy)
@@ -0,0 +1,48 @@
+/* { dg-require-effective-target mmap } */
+
+#include <sys/mman.h>
+#include <stdio.h>
+#include "tree-vect.h"
+
+#define COUNT 320
+#define MMAP_SIZE 0x10000
+#define ADDRESS 0x1122000000
+#define TYPE double
+
+#ifndef MAP_ANONYMOUS
+#define MAP_ANONYMOUS MAP_ANON
+#endif
+
+void __attribute__((noinline))
+foo (TYPE *__restrict a, TYPE *__restrict b)
+{
+  int n;
+
+  b = __builtin_assume_aligned (b, sizeof (TYPE) * 2);
+  a = __builtin_assume_aligned (a, sizeof (TYPE) * 2);
+  for (n = 0; n < COUNT; n++)
+    {
+      a[n] = b[n * 4] + b[n * 4 + 1];
+    }
+}
+
+int
+main (void)
+{
+  void *x;
+  size_t b_offset;
+
+  check_vect ();
+
+  x = mmap ((void *) ADDRESS, MMAP_SIZE, PROT_READ | PROT_WRITE,
+	    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  if (x == MAP_FAILED)
+    {
+      perror ("mmap");
+      return 1;
+    }
+
+  b_offset = MMAP_SIZE - (4 * COUNT - 2) * sizeof (TYPE);
+  foo ((TYPE *) x, (TYPE *) ((char *) x + b_offset));
+  return 0;
+}