[Bug lto/60319] wrong code (that hangs) by LTO at -Os and above on x86_64-linux-gnu

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60319

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-02-24
     Ever confirmed|0                           |1

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Zhendong Su from comment #5)
> Did you separately compile the two files at -O0 and link at -Os, like below? 
> 
> > $ gcc-trunk -flto -O0 -c foo.c
> > $ gcc-trunk -flto -O0 -c main.c
> > $ gcc-trunk -flto -Os foo.o main.o

Ah, no.  The issue here is that the fix for that bug I mention triggers
on TYPE_OVERFLOW_UNDEFINED, but with -O[01] we have -fno-strict-overflow
enabled and thus we lower it in a bogus way while with -O[s23] we
have -fstrict-overflow.  This is a IL semantic change that is not actually
contained in the IL ...

Anyway, confirmed.