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Re: Bug? flow_find_cross_jump deletes USE insns ...
Jakub Jelinek <jakub@redhat.com> writes:
> On Mon, Jan 14, 2002 at 12:56:22PM -0800, Richard Henderson wrote:
> > On Mon, Jan 14, 2002 at 04:56:53PM +0100, Ulrich Weigand wrote:
> > > The prolog on S/390 generates a USE insn for the GOT register,
> > > because the GOT pointer must be loaded even if it isn't used
> > > in the routine (because the PLT stubs rely on the register).
> >
> > This isn't going to work. Bare USE insns aren't meaningful
> > after reload. You need to add the USE to the call insn. You
> > can do this either inside the call pattern itself, or by adding
> > it to the CALL_INSN_FUNCTION_USAGE expr_list.
>
> I have a similar problem on IA-64, unfortunately there is no call where to
> stick the USEs in.
If you don't have any calls, how can the function throw?
...
> where the use is trying to make sure the set before it is not deleted:
> /* Even if we're not going to generate an epilogue, we still
> need to save the register so that EH works. */
> if (! epilogue_p)
> emit_insn (gen_rtx_USE (VOIDmode, alt_reg));
--
- Geoffrey Keating <geoffk@geoffk.org> <geoffk@redhat.com>