Is eliminate_regs_in_insn allowed to generate invalid instruction?

[Ulrich Weigand]

Ian Lance Taylor wrote:
> "Ulrich Weigand" <uweigand@de.ibm.com> writes:
> > The way some ports take around this issue is to recognize, in your
> > EXTRA_CONSTRAINT_STR implementation, certain forms of complex
> > addresses as those which you *know* reload will already have marked
> > for reloading, and therefore *accept* them (if they'd otherwise
> > match the constraint).
> 
> Seems like you could also just use find_replacement if
> reload_in_progress is true.

Unfortunately that doesn't work, because find_replacement can only
be used during the later phases of reload, where find_reloads was
called with a nonzero REPLACE parameter.  During the early phases,
where find_reloads is called with zero as REPLACE parameter, the
replacements structure is not filled in, and find_replacement does
not work.  A back-end memory constraint callback also needs to work
during those early phases, however ...

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com