re PR tree-optimization/86927 (Gcc miscompiles at -O3 on valid code)

2018-08-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/86927
	* tree-vect-loop.c (vect_create_epilog_for_reduction): Properly
	use const cond reduction code.

	* gcc.dg/vect/pr86927.c: New testcase.

From-SVN: r263888

gcc/ChangeLog

+2018-08-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/86927
+	* tree-vect-loop.c (vect_create_epilog_for_reduction): Properly
+	use const cond reduction code.
+
 2018-08-27  Alexander Monakov  <amonakov@ispras.ru>
 
 	PR tree-optimization/85758

gcc/testsuite/ChangeLog

+2018-08-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/86927
+	* gcc.dg/vect/pr86927.c: New testcase.
+
 2018-08-27  David Malcolm  <dmalcolm@redhat.com>
 
 	PR 87091

gcc/testsuite/gcc.dg/vect/pr86927.c

+#include "tree-vect.h"
+
+int a[28];
+int main()
+{
+  check_vect ();
+  a[4] = 1;
+  int c = 1;
+  for (int b = 0; b < 8; b++)
+    if (a[b])
+      c = 0;
+  if (c)
+    abort();
+  return 0;
+}

gcc/tree-vect-loop.c

@@ -5197,6 +5197,9 @@ vect_create_epilog_for_reduction (vec<tree> vect_defs,
 	  if (STMT_VINFO_VEC_REDUCTION_TYPE (stmt_info)
 	      == INTEGER_INDUC_COND_REDUCTION)
 	    code = induc_code;
+	  else if (STMT_VINFO_VEC_REDUCTION_TYPE (stmt_info)
+		   == CONST_COND_REDUCTION)
+	    code = STMT_VINFO_VEC_CONST_COND_REDUC_CODE (stmt_info);
 	  else
 	    code = MAX_EXPR;
 	}