re PR tree-optimization/84132 (tree-data-ref.c:3938: poor coding ?)

2018-01-31  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/84132
	* tree-data-ref.c (analyze_miv_subscript): Properly
	check whether evolution_function_is_affine_multivariate_p
	before calling gcd_of_steps_may_divide_p.

	* g++.dg/torture/pr84132.C: New testcase.

From-SVN: r257232

gcc/ChangeLog

+2018-01-31  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/84132
+	* tree-data-ref.c (analyze_miv_subscript): Properly
+	check whether evolution_function_is_affine_multivariate_p
+	before calling gcd_of_steps_may_divide_p.
+
 2018-01-31  Julia Koval  <julia.koval@intel.com>
 
 	PR target/83618

gcc/testsuite/ChangeLog

+2018-01-31  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/84132
+	* g++.dg/torture/pr84132.C: New testcase.
+
 2018-01-31  Jan Hubicka  <hubicka@ucw.cz>
 
 	* g++.dg/torture/pr81360.C: Drop unintended -O2 from dg-options and

gcc/testsuite/g++.dg/torture/pr84132.C

+/* { dg-do compile } */
+
+struct g {
+    char b;
+    unsigned char *d[];
+} e;
+unsigned char f;
+void i()
+{
+  for (int h;; h++)
+    {
+      unsigned a = h;
+      for (int c = 0; c < 256; c += 6)
+	for (int h = c; h < c + 6; h++)
+	  e.d[h + a] = &f;
+    }
+}

gcc/tree-data-ref.c

@@ -3976,9 +3976,8 @@ analyze_miv_subscript (tree chrec_a,
     }
 
   else if (evolution_function_is_constant_p (difference)
-	   /* For the moment, the following is verified:
-	      evolution_function_is_affine_multivariate_p (chrec_a,
-	      loop_nest->num) */
+	   && evolution_function_is_affine_multivariate_p (chrec_a,
+							   loop_nest->num)
 	   && !gcd_of_steps_may_divide_p (chrec_a, difference))
     {
       /* testsuite/.../ssa-chrec-33.c