[llvm] [IR] Add nowrap flags for trunc instruction (PR #85592)

[Yingwei Zheng via llvm-commits]

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@@ -27,6 +27,10 @@ bool Operator::hasPoisonGeneratingFlags() const {
     auto *OBO = cast<OverflowingBinaryOperator>(this);
     return OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap();
   }
+  case Instruction::Trunc: {
+    auto *TI = dyn_cast<TruncInst>(this);
+    return TI->hasNoUnsignedWrap() || TI->hasNoSignedWrap();
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dtcxzyw wrote:

`TI` may be null because this may be a CastConstantExpr.


https://github.com/llvm/llvm-project/pull/85592