[PATCH] D153148: [InstCombine] Fold `(-1 + zext(B)) & X` into `B ? 0 : X` where B is effectively a bool

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:2569
+  // Op0 & (-1 + zext(A)) --> A ? 0 : Op0
+  if (match(Op0, m_NSWAdd(m_ZExt(m_Value(A)), m_AllOnes())) &&
+      (A->getType()->isIntOrIntVectorTy(1) ||
----------------
goldstein.w.n wrote:
> The add doesn't need to be nsw
Why does this need a zext?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D153148/new/

https://reviews.llvm.org/D153148