[llvm-dev] RFC: cleanup in Transforms/Utils

Alina Sbirlea via llvm-dev llvm-dev at lists.llvm.org
Wed Jun 13 14:19:23 PDT 2018

Let me add one more specific question.
One method returns (does nothing) if BB.hasAddressTaken, while the other
replaces the block address with constant 1? I have zero background of the
usecase for the latter, so comments welcome.

I do agree with having a general version, they each have some functionality
the other does not, so the merge would be a superset of the two updating
all analyses when available.

On Wed, Jun 13, 2018 at 2:09 PM, Davide Italiano <dccitaliano at gmail.com>

> On Wed, Jun 13, 2018 at 2:04 PM, Alina Sbirlea <alina.sbirlea at gmail.com>
> wrote:
>> Hi,
>> I'm looking to see what's the best way to solve the fact that these two
>> utils mostly do the same thing:
>> 1. lib/Transforms/Utils/Local.cpp : MergeBasicBlockIntoOnlyPred
>> 2. lib/Transforms/Utils/BasicBlockUtils.cpp : MergeBlockIntoPredecessor
>> (+cc some of the folks who touched at least one of these either
>> originally or recently)
>> Brief overview:
>> 1. MergeBasicBlockIntoOnlyPred 2. MergeBlockIntoPredecessor
>> Update DT Update DT
>> Update either DT or DDT Updates LI and MemoryDependenceResults
>> Move all instructions from Pred to BB, delete Pred Move all instruction
>> from BB to Pred, delete BB
>> assert BB has single predecessor return if BB doesn't have a single
>> predecessor
>> Can I get some background on why there are two methods with such similar
>> functionality?
> I can't comment on whether there are two methods, but I wanted to merge
> them myself at some point (although other priorities showed up).
> I think we should keep the more general version and it should preserve the
> analyses.
> Thanks,
> --
> Davide
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