[PATCH] [SimplifyCFG] threshold for folding branches with common destination

Jingyue Wu jingyue at google.com
Tue Sep 30 09:51:48 PDT 2014

I understand now. Thanks!

Does the new patch look good to you?


On Mon Sep 29 2014 at 9:30:11 PM Owen Anderson <resistor at mac.com> wrote:

> On Sep 29, 2014, at 2:33 PM, Jingyue Wu <jingyue at google.com> wrote:
> > Hi Owen,
> >
> > I made the threshold a pass paramter in this patch. However, it doesn't
> look
> > pretty because there are several layers between
> createCFGSimplificationPass and
> > the actual use of this threshold (e.g. CFGSimplifyPass and
> SimplifyCFGOpt).
> >
> > What are the benefits of having these pass parameters? I saw other
> passes such
> > as JumpThreading and LoopUnroll have such pass parameters too, but none
> of them
> > seem actually used. One way I can think of using that is target-specific
> code
> > can create these passes with a customized threshold, but in that case, I
> feel
> > TargetTransformInfo would be a better home.
> The use case is for embedded uses of LLVM, to allow the client to have
> programmatic control.  We do something similar with loop unrolling
> thresholds, and I’d like to evolve the rest of the passes in that direction
> as well.
> —Owen
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