Flow crash for conditional branches against a constant

[Richard Earnshaw]

On Fri, 2004-06-11 at 16:54, Daniel Jacobowitz wrote:
> On Fri, Jun 11, 2004 at 11:47:33AM -0400, Ian Lance Taylor wrote:
> > Daniel Jacobowitz <drow@false.org> writes:
> > 
> > > I'm working on a port that has a branch instruction taking an unsigned
> > > immediate.  Something like this is valid:
> > > 
> > >   (set (pc) (if_then_else (ne (reg:SI 66) (const_int 1)))
> > >             (label_ref 1)
> > >             (pc))
> > > 
> > > But flow.c completely falls down on this construct.  For instance, that will
> > > cause not_reg_cond to abort because it is only prepared to handle comparison
> > > against 0.
> 
> I'm still investigating, but it looks like flow explicitly refuses to
> handle comparisons which are not against (const_int 0) - but
> HAVE_conditional_execution support doesn't.  Am I the first person
> foolish enough to try to use cond_exec patterns without cc0?
> 

Probably the first to try cond_exec, no cc0 and second operand of
comparison not zero all at the same time.  Any two of them should work
together, but possibly not all three.

R.