Re: Bootstrap failure on Linux/i686 in Ada

[Jeffrey A Law <law at redhat dot com>]

On Mon, 2006-01-02 at 19:31 +0100, Laurent GUERBY wrote:
> Hi Rainer, this is PR24994:
> 
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24994
> 
> And is under investigation:
> 
> http://gcc.gnu.org/ml/gcc-patches/2005-12/msg01756.html
> 
So, here's what appears to be happening.

  1. A statement is recorded into the EH throw
     statement hash table.

  2. SRA replaces the statement in the IL, but does
     not remove the statement from the EH throw
     statement table.  This is our bug.

  3. remove_cfg_annotations removes annotations from
     all the statements in the IL, but note that it
     does not walk the EH throw table (a reasonable thing
     since statements in the EH table ought to appear
     in the IL).

  4. Eventually the RTL optimizers run and remove the 
     block referenced by the bogus statement in the
     EH hash table.  

  5. Even later GC runs, walks the EH throw statement
     table, the bogus statement within the table, then
     the bogus statement's annotation, then the block
     in the annotation, which was expunged and unlinked
     leading to dereferencing a null pointer.

It'll take until tomorrow or so before I can get all the
bootstrapping and regression testing done, but I'm pretty
sure all we need to do is add 

remove_stmt_from_eh_region (orig_stmt);

into the appropriate location within bsi_replace.

jeff