[PATCH] D22696: [CodeGenPrep] Skip merging empty case blocks

[Xinliang David Li via llvm-commits]

On Fri, Nov 18, 2016 at 2:28 PM, Jun Bum Lim <junbuml at codeaurora.org> wrote:

> junbuml added a comment.
>
> > Do you know how often BPI/BFI is actually needed? In other words, among
> all functions compiled, how many of them reach to the point that BFI is
> needed? If you have some stats that will be great. If the data shows not
> often -- then BPI/BFI may need to be computed in a lazy way.
>
> I'm quite sure that BPI/BFI would be rarely used as we specifically look
> for empty blocks which has unique predecessor terminated by SwitchInst or
> IndirectBrInst. We can compute BPI/BFI in isMergingEmptyBlockProfitable()
> and then cache it only for the current function.  Please let me know if you
> see any down side of it?
>

No -- minimizing compile time cost is something good to shoot for.

David


>
>
> https://reviews.llvm.org/D22696
>
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>
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