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Re: [tree-ssa] Block merging (updated)
On Tue, Jan 13, 2004 at 11:05:23AM -0700, law@redhat.com wrote:
> In message <20040113170655.GA13204@atrey.karlin.mff.cuni.cz>, Zdenek Dvorak wri
> tes:
> >here is the patch. Btw., why is it so crucial to preserve these labels?
> It's been policy for over a decade to not delete user labels.
>
> >Their removal would only occur during optimizing compilation, so the
> >fact that the debug info would be incomplete is not that serious.
> Depends on your point of view.
We don't delete them, but we also don't leave them in any particularly
meaningful place. We've gotten at least one PR about this from someone
trying to use labels to automatically examine object code.
RTH wrote:
Labels that are not actively involved with control flow will have
no fixed anchor, and will float about somewhat randomly. This can't
be helped without severely pessimizing code generation.
I suspect, as the compiler gets better, "actively involved with control
flow" is going to get looser and looser. So I don't know what
guaranteeing that a label with this name will appear in the debug info
"somewhere" accomplishes.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer