[PATCH] D60673: [SimplifyCFG] Improove and speed up ReduceSwitchRange

[Shawn Landden via Phabricator via llvm-commits]

shawnl abandoned this revision.
shawnl marked 2 inline comments as done.
shawnl added a comment.

I think this patch will make more sense together with the other changes I want to make. I will withdraw it and submit the changes together.



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Comment at: lib/Transforms/Utils/SimplifyCFG.cpp:5498
-  uint64_t NumCases = Values.size();
-  // 40% is the default density for building a jump table in optsize/minsize mode.
-  uint64_t MinDensity = 40;
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lebedev.ri wrote:
> So what about `-Os`/`-Oz`?
This is not making the table, that calculation is elsewhere. This optimization is cheap and should always be applied.


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Comment at: lib/Transforms/Utils/SimplifyCFG.cpp:5629-5633
   // The conversion from switch to lookup tables results in difficult-to-analyze
   // code and makes pruning branches much harder. This is a problem if the
   // switch expression itself can still be restricted as a result of inlining or
   // CVP. Therefore, only apply this transformation during late stages of the
   // optimisation pipeline.
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lebedev.ri wrote:
> Did you see this comment?
This change does not change whether a lookup table gets created (although I am working on such patches). It only simplifies the switch.


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