[llvm] [ValueTracking] Handle `icmp pred (trunc X), C` in `computeKnownBitsFromCmp` (PR #82803)

[Nikita Popov via llvm-commits]

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@@ -27,7 +27,8 @@ static void findAffectedValues(Value *Cond,
 
       // Peek through unary operators to find the source of the condition.
       Value *Op;
-      if (match(I, m_PtrToInt(m_Value(Op)))) {
+      if (match(I,
+                m_CombineOr(m_PtrToInt(m_Value(Op)), m_Trunc(m_Value(Op))))) {
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nikic wrote:

Can you please also add a test using assume? I think to make it work you need to move the logic from computeKnownBitsFromCond into computeKnownBitsFromCmp.

https://github.com/llvm/llvm-project/pull/82803