tree-optimization/116768 - wrong dependence analysis

The following reverts a bogus fix done for PR101009 and instead makes
sure we get into the same_access_functions () case when computing
the distance vector for g[1] and g[1] where the constants ended up
having different types.  The generic code doesn't seem to handle
loop invariant dependences.  The special case gets us both
( 0 ) and ( 1 ) as distance vectors while formerly we got ( 1 ),
which the PR101009 fix changed to ( 0 ) with bad effects on other
cases as shown in this PR.

	PR tree-optimization/116768
	* tree-data-ref.cc (build_classic_dist_vector_1): Revert
	PR101009 change.
	* tree-chrec.cc (eq_evolutions_p): Make sure (sizetype)1
	and (int)1 compare equal.

	* gcc.dg/torture/pr116768.c: New testcase.

gcc/testsuite/gcc.dg/torture/pr116768.c

@@ -0,0 +1,32 @@
+/* { dg-do run } */
+
+#define numwords 2
+
+typedef struct {
+  unsigned words[numwords];
+} Child;
+
+typedef struct {
+  Child child;
+} Parent;
+
+Parent my_or(Parent x, const Parent *y) {
+  const Child *y_child = &y->child;
+  for (int i = 0; i < numwords; i++) {
+    x.child.words[i] |= y_child->words[i];
+  }
+  return x;
+}
+
+int main() {
+  Parent bs[4];
+  __builtin_memset(bs, 0, sizeof(bs));
+
+  bs[0].child.words[0] = 1;
+  for (int i = 1; i <= 3; i++) {
+    bs[i] = my_or(bs[i], &bs[i - 1]);
+  }
+  if (bs[2].child.words[0] != 1)
+    __builtin_abort ();
+  return 0;
+}

gcc/tree-chrec.cc

@@ -1716,7 +1716,7 @@ eq_evolutions_p (const_tree chrec0, const_tree chrec1)
       || TREE_CODE (chrec0) != TREE_CODE (chrec1))
     return false;
 
-  if (chrec0 == chrec1)
+  if (operand_equal_p (chrec0, chrec1, 0))
     return true;
 
   if (! types_compatible_p (TREE_TYPE (chrec0), TREE_TYPE (chrec1)))
@@ -1743,7 +1743,7 @@ eq_evolutions_p (const_tree chrec0, const_tree chrec1)
 			      TREE_OPERAND (chrec1, 0));
 
     default:
-      return operand_equal_p (chrec0, chrec1, 0);
+      return false;
     }
 }
 

gcc/tree-data-ref.cc

@@ -5223,8 +5223,6 @@ build_classic_dist_vector_1 (struct data_dependence_relation *ddr,
 	  non_affine_dependence_relation (ddr);
 	  return false;
 	}
-      else
-	*init_b = true;
     }
 
   return true;