[PATCH] D142519: [KnownBits] Add blsi and blsmsk

Wed Jan 25 00:08:59 PST 2023

foad added a comment.

Personally I still think this is too much extra complexity for uncertain benefit, but I won't stand in the way if the other reviewers are happy.

In any case the comments need work and the new functions should have exhaustive tests.

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Comment at: llvm/lib/Support/KnownBits.cpp:639-642
+// TODO: It's possible for use to have more information on `XMinusC` than `X`
+// (if there is an assume or branch on `X-C` for example). The logic could be
+// more complete by trying to get min set bit from (XMinusOne + C). Note, `C`
+// is generally `-1` but in some cases can be shrunk by SimplifyDemandedBits.
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This description seems confused about whether C is added to X or subtracted from X.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D142519/new/

https://reviews.llvm.org/D142519