re PR tree-optimization/50067 (Wrong code with -fpredictive-commoning)

2011-08-24  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/50067
	* tree-data-ref.c (dr_analyze_indices): Do not add an access
	function for a MEM_REF base that has no evolution in the loop
	nest or that is not analyzable.

	* gcc.dg/torture/pr50067-3.c: New testcase.
	* gcc.dg/torture/pr50067-4.c: Likewise.
	* gcc.dg/torture/pr50067-5.c: Likewise.

From-SVN: r178028

gcc/ChangeLog

+2011-08-24  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/50067
+	* tree-data-ref.c (dr_analyze_indices): Do not add an access
+	function for a MEM_REF base that has no evolution in the loop
+	nest or that is not analyzable.
+
 2011-08-23  Vladimir Makarov  <vmakarov@redhat.com>
 
 	* ira.c (ira_init_register_move_cost): Check small subclasses

gcc/testsuite/ChangeLog

+2011-08-24  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/50067
+	* gcc.dg/torture/pr50067-3.c: New testcase.
+	* gcc.dg/torture/pr50067-4.c: Likewise.
+	* gcc.dg/torture/pr50067-5.c: Likewise.
+
 2011-08-23  Kirill Yukhin  <kirill.yukhin@intel.com>
 
 	* g++.dg/other/i386-2.C: Add -mavx2 check.

gcc/testsuite/gcc.dg/torture/pr50067-3.c

+/* { dg-do run } */
+/* { dg-options "-fpredictive-commoning" } */
+
+extern void abort (void);
+int a[6] = { 0, 0, 0, 0, 7, 0 };
+static int *p = &a[4];
+
+int
+main ()
+{
+  int i;
+  for (i = 0; i < 4; ++i)
+    {
+      a[i + 1] = a[i + 2] > i;
+      *p &= ~1;
+    }
+  if (a[4] != 0)
+    abort ();
+  return 0;
+}

gcc/testsuite/gcc.dg/torture/pr50067-4.c

+/* { dg-do run } */
+
+/* Verify we do not get a bogus access function with 0B vs. 1B which
+   disambiguates both accesses and leads to vectorization.  */
+
+extern int memcmp(const void *, const void *, __SIZE_TYPE__);
+extern void abort (void);
+short a[33] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 };
+short b[33] = { 0, };
+int main()
+{
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+  int i;
+  if (sizeof (short) == 2)
+    {
+      for (i = 0; i < 64; ++i)
+	{
+	  (*((char(*)[])&a[1]))[i] = (*((char(*)[])&a[0]))[i+1];
+	}
+      if (memcmp (&a, &b, sizeof (a)) != 0)
+	abort ();
+    }
+#endif
+  return 0;
+}

gcc/testsuite/gcc.dg/torture/pr50067-5.c

+/* { dg-do run } */
+
+/* Verify we do not get a bogus access function pairs with
+   exchanged dimensions, 0, {1, +, 1}_1 vs. {2B, +, 1}_1, 0 which
+   disambiguates both accesses and leads to vectorization.  */
+
+extern int memcmp(const void *, const void *, __SIZE_TYPE__);
+extern void abort (void);
+short a[33] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 };
+short b[33] = { 0, };
+char * volatile ap_ = (char *)&a[0];
+int main()
+{
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+  int i;
+  char *ap = ap_;
+  if (sizeof (short) == 2)
+    {
+      for (i = 0; i < 64; ++i)
+	{
+	  (*((char(*)[])&ap[i+2]))[0] = (*((char(*)[])&ap[0]))[i+1];
+	}
+      if (memcmp (&a, &b, sizeof (a)) != 0)
+	abort ();
+    }
+#endif
+  return 0;
+}

gcc/tree-data-ref.c

@@ -881,25 +881,32 @@ dr_analyze_indices (struct data_reference *dr, loop_p nest, loop_p loop)
       aref = TREE_OPERAND (aref, 0);
     }
 
+  /* If the address operand of a MEM_REF base has an evolution in the
+     analyzed nest, add it as an additional independent access-function.  */
   if (TREE_CODE (aref) == MEM_REF)
     {
       op = TREE_OPERAND (aref, 0);
       access_fn = analyze_scalar_evolution (loop, op);
       access_fn = instantiate_scev (before_loop, loop, access_fn);
-      base = initial_condition (access_fn);
-      split_constant_offset (base, &base, &off);
-      if (!integer_zerop (TREE_OPERAND (aref, 1)))
+      if (TREE_CODE (access_fn) == POLYNOMIAL_CHREC)
 	{
-	  off = size_binop (PLUS_EXPR, off,
-			    fold_convert (ssizetype, TREE_OPERAND (aref, 1)));
-	  TREE_OPERAND (aref, 1)
-	    = build_int_cst (TREE_TYPE (TREE_OPERAND (aref, 1)), 0);
+	  base = initial_condition (access_fn);
+	  split_constant_offset (base, &base, &off);
+	  /* Fold the MEM_REF offset into the evolutions initial
+	     value to make more bases comparable.  */
+	  if (!integer_zerop (TREE_OPERAND (aref, 1)))
+	    {
+	      off = size_binop (PLUS_EXPR, off,
+				fold_convert (ssizetype,
+					      TREE_OPERAND (aref, 1)));
+	      TREE_OPERAND (aref, 1)
+		= build_int_cst (TREE_TYPE (TREE_OPERAND (aref, 1)), 0);
+	    }
+	  access_fn = chrec_replace_initial_condition
+	      (access_fn, fold_convert (TREE_TYPE (base), off));
+	  TREE_OPERAND (aref, 0) = base;
+	  VEC_safe_push (tree, heap, access_fns, access_fn);
 	}
-      access_fn = chrec_replace_initial_condition (access_fn,
-			fold_convert (TREE_TYPE (base), off));
-
-      TREE_OPERAND (aref, 0) = base;
-      VEC_safe_push (tree, heap, access_fns, access_fn);
     }
 
   if (TREE_CODE (ref) == MEM_REF