re PR tree-optimization/31343 (ICE in data-refs dependence testing)

	PR tree-optimization/31343
	* tree-chrec.h (chrec_zerop): Moved before build_polynomial_chrec.
	(build_polynomial_chrec): Return a scalar when the evolution is zero.
	* testsuite/gcc.dg/vect/pr31343.c: New.

From-SVN: r123708

gcc/ChangeLog

+2007-04-10  Sebastian Pop  <sebastian.pop@inria.fr>
+
+	PR tree-optimization/31343
+	* tree-chrec.h (chrec_zerop): Moved before build_polynomial_chrec.
+	(build_polynomial_chrec): Return a scalar when the evolution is zero.
+	* testsuite/gcc.dg/vect/pr31343.c: New.
+
 2007-04-10  Eric Christopher  <echristo@apple.com>
 
 	* config/i386/i386.h (X87_FLOAT_MODE_P): New.

gcc/testsuite/gcc.dg/vect/pr31343.c

+/* { dg-do compile } */
+
+#define N 16
+ 
+struct
+{
+  unsigned int x;
+  unsigned int y;
+} pS [100];
+
+void
+main1 ()
+{
+  int i, j;
+  unsigned int ub[N] =
+    { 1, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45 };
+  unsigned int uc[N] =
+    { 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
+  unsigned int udiffx, udiffy;
+
+  for (i = 0; i < N; i++)
+    {
+      pS[i].x = 0;
+      pS[i].y = 0;
+      for (j = 0; j < N; j++)
+      {
+        udiffx = (ub[j] - uc[j]);
+        udiffy = (ub[j] - uc[j]);
+        pS[i].x = udiffx;
+        pS[i].y = udiffy;
+      }
+    }
+}
+
+/* { dg-final { cleanup-tree-dump "vect" } } */

gcc/tree-chrec.h

@@ -84,7 +84,19 @@ extern bool evolution_function_is_affine_multivariate_p (tree);
 extern bool evolution_function_is_univariate_p (tree);
 extern unsigned nb_vars_in_chrec (tree);
 
-
+/* Determines whether CHREC is equal to zero.  */
+
+static inline bool 
+chrec_zerop (tree chrec)
+{
+  if (chrec == NULL_TREE)
+    return false;
+  
+  if (TREE_CODE (chrec) == INTEGER_CST)
+    return integer_zerop (chrec);
+  
+  return false;
+}
 
 /* Build a polynomial chain of recurrence.  */
 
@@ -99,28 +111,13 @@ build_polynomial_chrec (unsigned loop_num,
 
   gcc_assert (TREE_TYPE (left) == TREE_TYPE (right));
 
+  if (chrec_zerop (right))
+    return left;
+
   return build3 (POLYNOMIAL_CHREC, TREE_TYPE (left), 
 		 build_int_cst (NULL_TREE, loop_num), left, right);
 }
 
-
-
-/* Observers.  */
-
-/* Determines whether CHREC is equal to zero.  */
-
-static inline bool 
-chrec_zerop (tree chrec)
-{
-  if (chrec == NULL_TREE)
-    return false;
-  
-  if (TREE_CODE (chrec) == INTEGER_CST)
-    return integer_zerop (chrec);
-  
-  return false;
-}
-
 /* Determines whether the expression CHREC is a constant.  */
 
 static inline bool