[Bug rtl-optimization/25791] -O2 execution fails, -O and -g work

["ebotcazou at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #6 from ebotcazou at gcc dot gnu dot org  2006-01-17 06:59 -------
> (gdb) run
> Starting program:
> /afs/ir.stanford.edu/users/g/u/guertin/wylsrc/wylbur.ge
> 
> 
> Program received signal SIGILL, Illegal instruction.
> 0x00297064 in hex_to_character ()
> (gdb) where
> #0  0x00297064 in hex_to_character ()
> #1  0x00297068 in hex_to_character ()
> Previous frame identical to this frame (corrupt
> stack?)

Could you post an excerpt of the assembly code around 0x00297064?

> As you can see, your suggested change did NOT fix the 'problem'.

Well, it was not meant to, my wording was "and see what happens".

> What is obvious to me is that -O2 is affecting address computations.

What did you mean exactly?  Sure, -O2 is expected to have a negative impact on
debugging.

> There shouldn't be any way to clobber the stack unless addresses are
> mis-computed or not stored into variables when they
> should.  As far as I'm concerned, -O2 is a violation
> of the ISO standards concerning Optimization.

Well, if there is a code generation bug somewhere, things are expected to go
badly at some point.  That doesn't mean we should throw the baby with the bath
water.

> If you need the source code, I can bundle it into a tar.z
> file and make it available for download over the web.

No, we need a preprocessed testcase, preferably a runnable testcase but a
compilable one is sufficient if you can pinpoint the miscompilation.  That's
explained at the URL I previously posted: http://gcc.gnu.org/bugs.html.

Thanks in advance.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25791