c++/4512: New ICE in loop_iterations at unroll.c:3510,regression vs. 3.0.1

[Mark Mitchell]

--On Thursday, October 11, 2001 04:19:55 PM +0200 Wolfgang Bangerth 
<wolfgang.bangerth@iwr.uni-heidelberg.de> wrote:

>
>> Synopsis: New ICE in loop_iterations at unroll.c:3510, regression vs.
>> 3.0.1 State-Changed-From-To: open->closed
>
> Thanks for looking into it, but then there must be a different bug lurking
> somewhere: while your patch fixes the testcase it still does not fix
> compilation of my library. I unfortunately don't have the time today to
> reduce it again from the original code, so I can only send you the
> preprocessed source which is somewhat largish, but I hope you can still
> figure out what is going on.

Better the devil we know that the devil we don't.

I am going to revert Franz's patches on the branch.  They still seem
reasonable to me -- but since I have reviewed them twice, and missed
something twice, my confidence level is low.  Franz, please continue to
work on this on the mainline, and once 3.0.2 is out, let's move these
changes into 3.0.3.

(It also occurs to me that ideally this check for back edges would
be done using the basic block structures, but I don't know if
that is practical.)

--
Mark Mitchell                   mark@codesourcery.com
CodeSourcery, LLC               http://www.codesourcery.com