Re: middle-end/10472: [3.4 regression] ICE in instantiate_virtual_regs_lossage

[Wolfgang Bangerth <bangerth@ices.utexas.edu>]

The following reply was made to PR middle-end/10472; it has been noted by GNATS.

From: Wolfgang Bangerth <bangerth@ices.utexas.edu>
To: "Kaveh R. Ghazi" <ghazi@caip.rutgers.edu>
Cc: gcc-bugs@gcc.gnu.org, <gcc-gnats@gcc.gnu.org>, <ghazi@gcc.gnu.org>,
   Giovanni Bajo <giovannibajo@libero.it>, <gcc-patches@gcc.gnu.org>
Subject: Re: middle-end/10472: [3.4 regression] ICE in instantiate_virtual_regs_lossage
Date: Thu, 1 May 2003 19:32:14 -0500 (CDT)

 > First I tried to determine under what circumstances and platforms the
 > bug appears.  While the PR was opened against cygwin, it seems it
 > should occur on any x86 target.
 
 I'm sorry, I should have made that clearer: the reduced testcase ICEs on 
 my plain vanilla x86-linux-gnu box with SuSE 8.0.
 
 
 > (and why I'm not being chased with torches and pitchforks)
 
 We write hate-mails these days -- mental torture is just as effective :-)
 
 
 > BTW, IMHO the reduced testcase in the PR is slightly misleading.  It
 > lead me at least to believe the bug had something to do with null
 > pointers.
 
 Again my fault. 
 
 
 > In the mean time, we can disable the optmization on x86 so that cygwin
 > people can resume bootstrap.  (Yes this is lame, sorry I'm not able to
 > provide a proper fix.)
 
 Alternatively, one could work around the bootstrap failure with something 
 like the following instead of your small testcase (I'm surprised this 
 works):
     void foo (char *s)
     {
       char * tmp = __builtin_stpcpy (s, "hi");
       f (tmp);
     }
 That's just as lame, and fragile on top of that, but we don't have to wield 
 the sledgehammer to stomp this bug, it would be simpler to add a testcase 
 and we don't have to remember to re-enable the optimization once someone 
 gets around to fixing the underlying problem. There can't be that many 
 places in gcc where such a fix would be necessary, and Giovanni would 
 surely be willing to find them on his box, right? :-)
 
 W.
 
 -------------------------------------------------------------------------
 Wolfgang Bangerth              email:            bangerth@ices.utexas.edu
                                www: http://www.ices.utexas.edu/~bangerth/