[PATCH] Ensure gimplify_one_sizepos doesn't change something with INTEGER_TYPE into something with e.g. ENUMERAL_TYPE (PR middle-end/55851)

[Jakub Jelinek]

Hi!

As discussed in the PR, as all INTEGRAL_TYPE_P types with the same
sign/precision are usually considered compatible
(useless_type_conversion_p), during gimplify_one_sizepos the gimplifier
can change e.g. an integer expression into e.g. VAR_DECL with ENUMERAL_TYPE,
and when the gimplifier later on passes that to size_binop etc., it can
trigger asserts because ENUMERAL_TYPE isn't considered sizetype-ish enough.

The following patch (which I don't like too much admittedly) makes sure
for constants we fold it back to INTEGER_TYPE constant, and for VAR_DECLs
add an extra VAR_DECL in such a case.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Or do you prefer some other way?

2013-01-04  Jakub Jelinek  <ja...@redhat.com>

        PR middle-end/55851
        * gimplify.c (gimplify_one_sizepos): Ensure gimplify_expr
        doesn't turn *expr_p from INTEGER_TYPE expression into e.g.
        ENUMERAL_TYPE expression.

        * gcc.c-torture/compile/pr55851.c: New test.

--- gcc/gimplify.c.jj   2012-12-20 19:13:00.000000000 +0100
+++ gcc/gimplify.c      2013-01-03 16:16:07.288707387 +0100
@@ -8180,6 +8180,26 @@ gimplify_one_sizepos (tree *expr_p, gimp
   *expr_p = unshare_expr (expr);
 
   gimplify_expr (expr_p, stmt_p, NULL, is_gimple_val, fb_rvalue);
+
+  /* Ensure we don't change an INTEGER_TYPE expression into e.g. ENUMERAL_TYPE
+     expression.  */
+  if (TREE_CODE (TREE_TYPE (*expr_p)) != TREE_CODE (TREE_TYPE (expr)))
+    {
+      gcc_checking_assert (useless_type_conversion_p (TREE_TYPE (expr),
+                                                     TREE_TYPE (*expr_p)));
+      if (TREE_CODE (*expr_p) == INTEGER_CST)
+       *expr_p = fold_convert (TREE_TYPE (expr), *expr_p);
+      else
+       {
+         tree var = create_tmp_var (TREE_TYPE (expr), NULL);
+         tree mod = build2 (INIT_EXPR, TREE_TYPE (var),
+                            var, unshare_expr (*expr_p));
+         SET_EXPR_LOCATION (mod, EXPR_LOC_OR_HERE (*expr_p));
+         gimplify_and_add (mod, stmt_p);
+         ggc_free (mod);
+         *expr_p = var;
+       }
+    }
 }
 
 /* Gimplify the body of statements of FNDECL and return a GIMPLE_BIND node
--- gcc/testsuite/gcc.c-torture/compile/pr55851.c.jj    2013-01-03 
16:20:19.085284806 +0100
+++ gcc/testsuite/gcc.c-torture/compile/pr55851.c       2013-01-03 
16:19:27.698571718 +0100
@@ -0,0 +1,12 @@
+/* PR middle-end/55851 */
+
+enum { A = 1UL, B = -1UL } var = A;
+void foo (char *);
+
+void
+test (void)
+{
+  char vla[1][var];
+  vla[0][0] = 1;
+  foo (&vla[0][0]);
+}

        Jakub