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.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@123708 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 16 insertions, 19 deletions

diff --git a/gcc/tree-chrec.h b/gcc/tree-chrec.h
index c22867ba0d2..95c6f384dde 100644
--- a/gcc/tree-chrec.h
+++ b/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