[PATCH] Fix PR67120

[Richard Biener]

The following fixes comparing of &i and &i if i is volatile.  We were
using operand_equal_p to compare i with i which of course results in
a false negative.  The following restricts us to the interesting
cases (SSA names and decls) and then simply use ==.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2015-08-05  Richard Biener  <rguent...@suse.de>

        PR middle-end/67120
        * match.pd: Compare address bases with == if they are decls
        or SSA names, not operand_equal_p.  Otherwise fail.

        * gcc.dg/torture/pr67120.c: New testcase.

Index: gcc/match.pd
===================================================================
--- gcc/match.pd        (revision 226612)
+++ gcc/match.pd        (working copy)
@@ -1848,13 +1920,14 @@ (define_operator_list CBRT BUILT_IN_CBRT
    (if (base0 && base1)
     (with
      {
-       int equal;
+       int equal = 2;
        if (decl_in_symtab_p (base0)
           && decl_in_symtab_p (base1))
          equal = symtab_node::get_create (base0)
                   ->equal_address_to (symtab_node::get_create (base1));
-       else
-         equal = operand_equal_p (base0, base1, 0);
+       else if ((DECL_P (base0) || TREE_CODE (base0) == SSA_NAME)
+               && (DECL_P (base1) || TREE_CODE (base1) == SSA_NAME))
+         equal = (base0 == base1);
      }
      (if (equal == 1
          && (cmp == EQ_EXPR || cmp == NE_EXPR
Index: gcc/testsuite/gcc.dg/torture/pr67120.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr67120.c      (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr67120.c      (working copy)
@@ -0,0 +1,16 @@
+/* { dg-do run } */
+
+volatile int *volatile *a;
+static volatile int *volatile **b = &a;
+
+int
+main ()
+{
+  volatile int *volatile c;
+  *b = &c;
+
+  if (a != &c) 
+    __builtin_abort (); 
+
+  return 0;
+}