[DebugInfo][InferAddressSpaces] Missing debug location update for the new addrspacecast instruction

[Apochens]

InferAddressSpaces-L643

In function cloneInstructionWithNewAddressSpace, the new addrspacecast instruction NewI has no debug location and assigning the debug location of I to it is appropriate. Because it is a cast of I.

  if (AS != UninitializedAddressSpace) {
    // For the assumed address space, insert an `addrspacecast` to make that
    // explicit.
    Type *NewPtrTy = getPtrOrVecOfPtrsWithNewAS(I->getType(), AS);
->  auto *NewI = new AddrSpaceCastInst(I, NewPtrTy);
    NewI->insertAfter(I);
    return NewI;
  }

Acctually, there is a debug location update for the return value of this function (cloneInstructionWithNewAddressSpace) in function cloneValueWithNewAddressSpace. However, it happens only when the return value has no parent block, which makes the addrspacecast instruction ignored.

    Value *NewV = cloneInstructionWithNewAddressSpace(
        I, NewAddrSpace, ValueWithNewAddrSpace, PredicatedAS, PoisonUsesToFix);
    if (Instruction *NewI = dyn_cast_or_null<Instruction>(NewV)) {
      if (NewI->getParent() == nullptr) {
        NewI->insertBefore(I);
        NewI->takeName(I);
->      NewI->setDebugLoc(I->getDebugLoc());
      }
    }

[llvmbot]

@llvm/issue-subscribers-debuginfo

Author: Shan Huang (Apochens)

[**InferAddressSpaces-L643**](https://github.com/llvm/llvm-project/blob/fadc72235ed59eba8538d803fba5c79cd9cda5e9/llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp#L643)

In function cloneInstructionWithNewAddressSpace, the new addrspacecast instruction NewI has no debug location and assigning the debug location of I to it is appropriate. Because it is a cast of I.

  if (AS != UninitializedAddressSpace) {
    // For the assumed address space, insert an `addrspacecast` to make that
    // explicit.
    Type *NewPtrTy = getPtrOrVecOfPtrsWithNewAS(I->getType(), AS);
->  auto *NewI = new AddrSpaceCastInst(I, NewPtrTy);
    NewI->insertAfter(I);
    return NewI;
  }

Acctually, there is a debug location update for the return value of this function (cloneInstructionWithNewAddressSpace) in function cloneValueWithNewAddressSpace. However, it happens only when the return value has no parent block, which makes the addrspacecast instruction ignored.

    Value *NewV = cloneInstructionWithNewAddressSpace(
        I, NewAddrSpace, ValueWithNewAddrSpace, PredicatedAS, PoisonUsesToFix);
    if (Instruction *NewI = dyn_cast_or_null<Instruction>(NewV)) {
      if (NewI->getParent() == nullptr) {
        NewI->insertBefore(I);
        NewI->takeName(I);
->      NewI->setDebugLoc(I->getDebugLoc());
      }
    }