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

[via llvm-commits]

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@@ -624,6 +643,13 @@ void Instruction::andIRFlags(const Value *V) {
     }
   }
 
+  if (auto *PNWI = dyn_cast<PossiblyNoWrapInst>(V)) {
+    if (isa<PossiblyNoWrapInst>(this)) {
+      setHasNoSignedWrap(hasNoSignedWrap() && PNWI->hasNoSignedWrap());
+      setHasNoUnsignedWrap(hasNoUnsignedWrap() && PNWI->hasNoUnsignedWrap());
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elhewaty wrote:

@nikic any hint about why is this causing assertions
```
opt: /media/mohamed/Local-Disk/open-source/NEW/llvm-project/llvm/include/llvm/Support/Casting.h:578: decltype(auto) llvm::cast(From*) [with To = llvm::OverflowingBinaryOperator; From = const llvm::Instruction]: Assertion `isa<To>(Val) && "cast<Ty>() argument of incompatible type!"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.

```

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