[PATCH] D133919: [InstCombine] Fold ((x?1:4)&(y?1:4))==0 to x^y

[Marc Auberer via Phabricator via llvm-commits]

marcauberer updated this revision to Diff 460858.
marcauberer added a comment.

Rebase


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D133919/new/

https://reviews.llvm.org/D133919

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp


Index: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -6472,6 +6472,22 @@
   if (Instruction *Res = foldReductionIdiom(I, Builder, DL))
     return Res;
 
+  {
+    Value *A, *B;
+    const APInt *C, *D;
+    // Find hidden xor optimization (only works if `and C, D` equals `0`)
+    // (icmp (and (select A, C, D), (select B, C, D)), 0) --> (xor A, B)
+    if (I.getPredicate() == ICmpInst::ICMP_EQ && match(Op0,
+      m_OneUse(m_c_And(
+        m_OneUse(m_Select(m_Value(A), m_APInt(C), m_APInt(D))),
+        m_OneUse(m_Select(m_Value(B), m_APInt(C), m_APInt(D)))
+      ))
+    ) && match(Op1, m_Zero())) {
+      if ((*C & *D) == 0)
+        return BinaryOperator::CreateXor(A, B);
+    }
+  }
+
   return Changed ? &I : nullptr;
 }
 


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