[llvm] [InstCombine] Handle trunc i1 pattern in eq-of-parts fold (PR #112704)

[Andreas Jonson via llvm-commits]

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@@ -1185,14 +1185,25 @@ static Value *extractIntPart(const IntPart &P, IRBuilderBase &Builder) {
 /// (icmp eq X0, Y0) & (icmp eq X1, Y1) -> icmp eq X01, Y01
 /// (icmp ne X0, Y0) | (icmp ne X1, Y1) -> icmp ne X01, Y01
 /// where X0, X1 and Y0, Y1 are adjacent parts extracted from an integer.
-Value *InstCombinerImpl::foldEqOfParts(ICmpInst *Cmp0, ICmpInst *Cmp1,
-                                       bool IsAnd) {
+Value *InstCombinerImpl::foldEqOfParts(Value *Cmp0, Value *Cmp1, bool IsAnd) {
   if (!Cmp0->hasOneUse() || !Cmp1->hasOneUse())
     return nullptr;
 
   CmpInst::Predicate Pred = IsAnd ? CmpInst::ICMP_EQ : CmpInst::ICMP_NE;
-  auto GetMatchPart = [&](ICmpInst *Cmp,
+  auto GetMatchPart = [&](Value *CmpV,
                           unsigned OpNo) -> std::optional<IntPart> {
+    Value *X, *Y;
+    // icmp ne (and x, 1), (and y, 1) <=> trunc (xor x, y) to i1
+    // icmp eq (and x, 1), (and y, 1) <=> not (trunc (xor x, y) to i1)
+    if (Pred == CmpInst::ICMP_NE
+            ? match(CmpV, m_Trunc(m_Xor(m_Value(X), m_Value(Y))))
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andjo403 wrote:

maybe nice to have a assert that the trunc is to i1 near here. I thought it was missing before finding the check first  in foldBooleanAndOr.

https://github.com/llvm/llvm-project/pull/112704