[llvm] [ValueTracking] Handle `trunc nuw` in `computeKnownBitsFromICmpCond` (PR #125414)

[Andreas Jonson via llvm-commits]

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@@ -776,7 +776,10 @@ static void computeKnownBitsFromICmpCond(const Value *V, ICmpInst *Cmp,
   if (match(LHS, m_Trunc(m_Specific(V)))) {
     KnownBits DstKnown(LHS->getType()->getScalarSizeInBits());
     computeKnownBitsFromCmp(LHS, Pred, LHS, RHS, DstKnown, SQ);
-    Known = Known.unionWith(DstKnown.anyext(Known.getBitWidth()));
+    if (match(LHS, m_NUWTrunc(m_Value())))
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andjo403 wrote:

as it is known that LHS is trunc is it better to do `cast<TruncInst>(LHS)->hasNoUnsignedWrap()` ?

https://github.com/llvm/llvm-project/pull/125414