[PATCH] D148275: [InstCombine] support fold select(X|Y,X|Y,X) to X|Y

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n added inline comments.


================
Comment at: llvm/lib/Analysis/InstructionSimplify.cpp:4585
 
+  if (Pred == ICmpInst::Predicate::ICMP_EQ) {
+    Value *X;
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Should we also have `select(X|Y != 0, X | Y, X or Y)`?


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Comment at: llvm/lib/Analysis/InstructionSimplify.cpp:4588
+    Value *Y;
+    // select(X | Y == 0, X or Y, X | Y) -> X | Y
+    if (match(CondVal, m_ICmp(Pred, m_Specific(FalseVal), m_Zero())) &&
----------------
You could also do:
`select(X | Y == X, X, X | Y)` -> `X | Y`
and
`select (X|Y == Y, Y, X|Y)` -> `X|Y`
https://alive2.llvm.org/ce/z/hawAog


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D148275/new/

https://reviews.llvm.org/D148275