[PATCH] D150100: [KnownBits] Improve implementation of `KnownBits::abs`

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
Comment at: llvm/lib/Support/KnownBits.cpp:423
+    KnownBits KnownNeg = computeForAddSub(
+        /*Add*/ false, /*NSW*/ false, Zero, *this);
+
----------------
You can pass IntMinIsPoison to the NSW argument.


================
Comment at: llvm/lib/Support/KnownBits.cpp:426
+    // NB: KnownAbs is not always a subset of KnownNeg so we want to get input
+    // from both.
+    KnownAbs.One |= KnownNeg.One;
----------------
Under which circumstance is KnownAbs better? Seems fishy.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D150100/new/

https://reviews.llvm.org/D150100