[PATCH] Fix gimplification bug with constructors

[Eric Botcazou]

Hi,

This is a regression present in the 4.x series of Ada compilers.

For

      V := (Components => Clone (V.Components));

we have in .original

  *v = {.components=p__clone ((natural___XDLU_0__2147483647[1:8] &) 
&v->components)};

and in .gimple

  D.1025 = &v->components;
  *v = {};
  v->components = p__clone (D.1025) [return slot optimization];

Now "Clone" dereferences its argument:

P.Clone (components)
{
  <retval> = *components;
  return <retval>;
}

so the block-clearing effectively clobbers the argument of "Clone".


It turns out that gimplify_init_ctor_preeval_1 already has a provision for 
"visible" dereferences within constructors:

  /* If the constructor component is indirect, determine if we have a
     potential overlap with the lhs.  The only bits of information we
     have to go on at this point are addressability and alias sets.  */
  if (TREE_CODE (t) == INDIRECT_REF
      && (!data->lhs_base_decl || TREE_ADDRESSABLE (data->lhs_base_decl))
      && alias_sets_conflict_p (data->lhs_alias_set, get_alias_set (t)))
    return t;

Here we have a "hidden" dereference, but we can still check the type of the 
parameters of the function.

Bootstrapped/regtested on i586-suse-linux, OK for mainline/4.2/4.1 branches?


2006-11-23  Eric Botcazou  <ebotcazou@adacore.com>

        * gimplify.c (gimplify_init_ctor_preeval_1): Detect potential overlap
        due to calls to functions taking pointers as parameters.


2006-11-23  Eric Botcazou  <ebotcazou@adacore.com>

	* gnat.dg/self_aggregate_with_call.adb: New test.


:ADDPATCH gimplifier:

-- 
Eric Botcazou
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