[LLVMdev] LLVM Inliner

[Xinliang David Li]

On Mon, Nov 29, 2010 at 1:17 AM, Duncan Sands <baldrick at free.fr> wrote:

> Hi David,
>
> > Interesting -- LLVM does perform on the fly cleanups during inlining
> > transformation -- this will make summary update precise. One thing I
> notice from
> > the debug pass dump is that the 'deduce function attribute' pass happens
> before
> > the clean up -- Is it intended?
>
> you are correct.  This is due to a limitation of the pass manager: it would
> clearly be better to run the function attributes pass after the
> per-function
> passes that follow the inliner, but currently if you try what happens is
> that
> first the inliner and on the fly cleanups get run on every function, and
> only
> when they have finished the function attributes pass gets run on every
> function.  That means that function attributes of callees will not have
> been
> calculated when the inliner (and the subsequent function passes) process a
> function, which is bad.  I think the pass manager should be fixed to not do
> this, at which point the function attributes pass could be moved later.
>

So bottom up traversal of the (scc node of) callgraph is not sufficient to
guarantee all callees are processed before the caller?

Thanks,

David


>
> Ciao,
>
> Duncan.
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