[PATCH] D147968: [TTI][BPF]: Undo specific transform-preventing passes and add TTI hooks

[David Li via Phabricator via llvm-commits]

davidxl added a comment.

Can we have a middle ground here. Instead of having too many new TTI interfaces here, a single one can be used instead: TTI:needsPreserveRangeInfoInVerification(). If this returns true, some passes (or subpasses in instcombine) can be turned off for the target.  Similar things are done in vectorizer.

Transformations that are guarded by this check also need to be checked case by case. If the verifier can be enhanced without too much compile time overhead, it should probably be done there -- it adds more benefit of allowing more flexibility in source patterns.

Legalization can be a longer term thing to to think about. Like undoing transformations (excluding pure canonicalization ones), it does add unnecessary compile time overhead.


Repository:
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  https://reviews.llvm.org/D147968/new/

https://reviews.llvm.org/D147968