[PATCH] D107233: [SimplifyCFG] Enable switch to lookup table for more types.

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added a comment.

In D107233#2922212 <https://reviews.llvm.org/D107233#2922212>, @fhahn wrote:

> In D107233#2922195 <https://reviews.llvm.org/D107233#2922195>, @lebedev.ri wrote:
>
>> In D107233#2922165 <https://reviews.llvm.org/D107233#2922165>, @fhahn wrote:
>>
>>> In D107233#2918643 <https://reviews.llvm.org/D107233#2918643>, @lebedev.ri wrote:
>>>
>>>> Can we just revert rL168970 <https://reviews.llvm.org/rL168970>?
>>>> What exactly was the `rdar://12779436` about, can anyone look it up?
>>>
>>> It's an Apple-internal bug report of a crash that was the reason for the revert. As long as the test that has been added in rL168970 <https://reviews.llvm.org/rL168970> passes that should be fine. I can also verify against the original C++ source.
>>
>> Note that most people don't have access to any such internal bugtrackers.
>> What was the crast?
>
> I guess in this case, the reference is a historical artifact. I assume the test added to `llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll` in the commit should be sufficient to guard against the reported issue.

I'm not sure i follow. Is it a profitability check, or is it guarding against some crash somewhere in backend?
We can nicely lower `i96` load, https://godbolt.org/z/scP8sj5jf, and i suspect it will still be more performant than the switch lowering.


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https://reviews.llvm.org/D107233