[PATCH] D144777: [InstCombine] Fold signbit test of a pow2 or zero

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp:1343
+  // icmp sgt (and (sub 0, X), X), -1 --> icmp ne (X, CI)
+  if (match(Op0, m_OneUse(m_And(m_Sub(m_Zero(), m_Value(X)), m_Deferred(X))))) {
+    Constant *CI = ConstantInt::get(
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There are other power of 2 patterns. Maybe use `isKnownPowerOf2`?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D144777/new/

https://reviews.llvm.org/D144777