| Issue |
120775
|
| Summary |
[VectorCombine] Handle shuffle of selects
|
| Labels |
missed-optimization,
llvm:transforms
|
| Assignees |
|
| Reporter |
RKSimon
|
VectorCombine can't currently fold `shuffle(select(c0,t0,f0), select(c1,t1,f1)) -> select(shuffle(c0,c1),shuffle(t0,t1),shuffle(f0,f1))` - although foldShuffleToIdentity can fold some very basic cases.
This is trickier than foldShuffleOfBinops etc. as the default increase in instruction count will likely prevent basic fold from succeeding (from a cost:benefit), so we will need to just handle cases where at least one of the folded inner shuffles gets simplified away.
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