Need help creating a small test case for g++ 4.0.0 bug

[Volker Reichelt]

Paul Leopardi wrote:

> I have now downloaded, bootstapped and installed gcc 4.0.1. The bug in g++ 
> optimization is still there. I've made an attempt to follow the instructions 
> on minimizing test cases and have so far accomplished:
> wc of old preprocessed source:
>   99412  260586 2965538 peg01.ii
> wc of new preprocessed source:
>   69309  241979 2668391 peg01.ii
> As you can see, this is not much of a reduction. The bug I'm seeing keeps 
> disappearing as I try to reduce the source code. It seems to be a subtle 
> interaction between the Barton-Nackman trick, Boost uBLAS, GNU hash_map and 
> the g++ flags -fstrict-aliasing and -finline-functions. If I try to eliminate 
> any of these, the bug disappears. 

You might want to try a recent snapshot of gcc 4.0.2, first.
Two aliasing bugs got fixed after the 4.0.1 release:

http://gcc.gnu.org/PR22591
http://gcc.gnu.org/PR23192

The first even caused std::list::swap to be miscompiled.

Regards,
Volker