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Re: [PATCH] Allow DCE of const or pure calls
On Sun, Nov 04, 2007 at 04:11:11PM -0800, Mark Mitchell wrote:
> Eric Botcazou wrote:
> >> 2007-11-02 Jakub Jelinek <jakub@redhat.com>
> >>
> >> * dce.c (deletable_insn_p): Make const or pure calls deletable.
> >
> > Note that flow.c didn't delete these calls (unless inside libcalls) so I'm not
> > sure we want this for 4.3.
>
> Do you mean that you think that this might be undesirable because it
> would be a surprise to users? Or because it's a new feature, and thus
> not suitable for Stage 3?
While the patch worked just fine during bootstrap/regtesting on
x86_64-linux, during later testing I found it caused a bootstrap failure
on ia64-linux (which I haven't had time to analyze yet).
Therefore I'm withdrawing that patch for now. Most of the dead const/pure calls
should be hopefully DCEd already in tree passes and at least in 4.3
__tls_get_addr etc. is using libcall blocks which are now DCEable again
even without this patch.
Jakub