From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-248737-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 18018 invoked by alias); 29 Mar 2008 10:53:38 -0000
Received: (qmail 17944 invoked by uid 48); 29 Mar 2008 10:52:56 -0000
Date: Sat, 29 Mar 2008 10:53:00 -0000
Message-ID: <20080329105256.17943.qmail@sourceware.org>
X-Bugzilla-Reason: CC
References: <bug-35708-10080@http.gcc.gnu.org/bugzilla/>
Subject: [Bug c++/35708] jump to label enters catch block
In-Reply-To: <bug-35708-10080@http.gcc.gnu.org/bugzilla/>
Reply-To: gcc-bugzilla@gcc.gnu.org
To: gcc-bugs@gcc.gnu.org
From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2008-03/txt/msg02363.txt.bz2



------- Comment #5 from rguenth at gcc dot gnu dot org  2008-03-29 10:52 -------
Here's a shorter testcase:

struct object { int one_o; int allocstamp; };
int pgci_pointable (object obj);
void foo(void);
int main (int argc, char *argv[])
{
  if (pgci_pointable((object){7,100}))
    {
      bad_rehash_size:
        foo();
    }
  goto bad_rehash_size;
}


If you look at the original IL as coming from the FE you see

  {
    <<cleanup_point     struct object D.1681 = {.one_o=7, .allocstamp=100};>>;
    <<< Unknown tree: if_stmt
       <<cleanup_point pgci_pointable (D.1681) != 0>>
       bad_rehash_size:;
         <<cleanup_point <<< Unknown tree: expr_stmt foo () >>> >>;
    >>> ;
  }
  goto bad_rehash_size;

which is gimplified to

  {
    {
      struct objectD.1670 D.1681;

      D.1681.one_oD.1672 = 7;
      D.1681.allocstampD.1673 = 100;
      D.1699 = pgci_pointable (D.1681);
      retval.0D.1698 = D.1699 != 0;
      if (retval.0D.1698)
        {
          bad_rehash_sizeD.1697:;
          foo ();
        }
      else
        {

        }
    }
    goto bad_rehash_sizeD.1697;
  }

at which point the goto enters a scope with local objects constructed
before the jump target.  Thus the FE generates a new scope around the
if statement where the temporary object is bound to and somehow this
is a of type sk_catch (that there is no checking whether something can
throw inside the block may be a problem).

With gcc 4.1 where the testcase is accepted we gimplify to

int main(int, char**) (argc, argv)
{
  boolD.1451 retval.0D.1759;
  struct objectD.1732 D.1760;
  intD.2 D.1761;
  intD.2 D.1762;

  D.1760.one_oD.1734 = 7;
  D.1760.allocstampD.1735 = 100;
  D.1761 = pgci_pointable (D.1760);
  retval.0D.1759 = D.1761 != 0;
  if (retval.0D.1759)
    {
      bad_rehash_sizeD.1758:;
      foo ();
    }
  else
    {

    }
  goto bad_rehash_sizeD.1758;

not creating this extra scope.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
      Known to fail|                            |4.2.3 4.3.0
      Known to work|                            |4.1.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35708