re PR tree-optimization/88792 (wrong-code in RPO VN since r263875)

2019-01-10  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/88792
	* tree-ssa-pre.c (get_representative_for): Do not return a
	value-number here.

	* gcc.dg/torture/pr88792.c: New testcase.

From-SVN: r267821

gcc/ChangeLog

+2019-01-10  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/88792
+	* tree-ssa-pre.c (get_representative_for): Do not return a
+	value-number here.
+
 2019-01-10  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/84877

gcc/testsuite/ChangeLog

+2019-01-10  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/88792
+	* gcc.dg/torture/pr88792.c: New testcase.
+
 2019-01-10  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	PR fortran/86322

gcc/testsuite/gcc.dg/torture/pr88792.c

+/* { dg-do run } */
+
+int one = 1;
+
+char
+__attribute__((noipa))
+foo(char v)
+{
+  int modec;
+
+  if (one)
+    {
+      modec = ((v < 'A' || v > 'Z') ? v : v + ('a' - 'A'));
+      if (modec != 't' && modec != 'c' && modec != 'g')
+	modec = 0;
+    }
+  else
+    modec = 'g';
+
+  return modec;
+}
+
+int main(int argc, char **argv)
+{
+  char c = 't';
+  int r = foo (c);
+
+  if (r != c)
+    __builtin_abort ();
+
+  return 0;
+}

gcc/tree-ssa-pre.c

@@ -1262,7 +1262,7 @@ get_representative_for (const pre_expr e, basic_block b = NULL)
   switch (e->kind)
     {
     case NAME:
-      return VN_INFO (PRE_EXPR_NAME (e))->valnum;
+      return PRE_EXPR_NAME (e);
     case CONSTANT:
       return PRE_EXPR_CONSTANT (e);
     case NARY: