i686 bootstrap failure on libgcc2.c

[Zack Weinberg]

On Wed, Jan 17, 2001 at 03:50:24PM +1300, Bryce McKinlay wrote:
> Zack Weinberg wrote:
> 
> > On Wed, Jan 17, 2001 at 02:43:36PM +1300, Bryce McKinlay wrote:
> > > I'm getting this error attempting to build the current tree:
> > >
> > > /home/bryce/cvs/gcc/build/gcc/xgcc -B/home/bryce/cvs/gcc/build/gcc/
> > > -B/home/bryce/gcc/i686-pc-linux-gnu/bin/
> > > -B/home/bryce/gcc/i686-pc-linux-gnu/lib/ -isystem
> > > /home/bryce/gcc/i686-pc-linux-gnu/include -O2   -DIN_GCC    -W -Wall
> > > -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -isystem
> > > ./include  -fPIC -g1 -DHAVE_GTHR_DEFAULT -DIN_LIBGCC2
> > > -D__GCC_FLOAT_NOT_NEEDED  -I. -I. -I../../gcc -I../../gcc/.
> > > -I../../gcc/config -I../../gcc/../include  -DL_divdi3 -c
> > > ../../gcc/libgcc2.c -o libgcc/./_divdi3.o
> > > ../../gcc/libgcc2.c: In function `__divdi3':
> > > ../../gcc/libgcc2.c:748: Internal compiler error in find_free_reg, at
> > > local-alloc.c:2149
> > > Please submit a full bug report.
> >
> > I get this too.
> >
> > However, backing them out does not remove the bug.  I don't see
> > anything else in the changelog that looks like it could have caused
> > this.
> 
> Reverting this combine patch seems to fix it:
> 
> Tue Jan 16 17:20:43 2001  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>
> 
>         * combine.c (try_combine): If i3_subst_into_i2, properly check for
>         I3 having more than one SET.

Yes, it does.  Now why on earth does that affect anything?  Basic
block 8 of __divdi3 as seen by local is identical before and after
that change, including the incorrect live-at-end info...

zw