yaxunl added inline comments.
================
Comment at: lib/CodeGen/CGBlocks.cpp:723
+ ? CGM.getNSConcreteStackBlock()
+ : llvm::Constant::getNullValue(
+ CGM.getNSConcreteStackBlock()->getType());
----------------
Anastasia wrote:
> yaxunl wrote:
> > should use CGM.getNullPointer to create a null pointer.
> Btw, does it mean we can no longer use generic llvm::Constant::getNullValue
> helper for PointerTypes? This feels wrong! Is it possible to extend the
> helper?
>
> Also I find it a bit counter intuitive to use getNullPointer with the second
> argument QualType for the case like this where we don't have an actual AST
> type. Why is it needed? Some documentation might be helpful here. :) Could we
> extend this helper to use default second argument or an overload with one
> argument only.
The LLVM type may not have sufficient information, so in general situation
QualType is needed. The comment before getNullPointer declaration explains the
meaning of the parameters:
```
/// Get target specific null pointer.
/// \param T is the LLVM type of the null pointer.
/// \param QT is the clang QualType of the null pointer.
/// \return ConstantPointerNull with the given type \p T.
/// Each target can override it to return its own desired constant value.
virtual llvm::Constant *getNullPointer(const CodeGen::CodeGenModule &CGM,
llvm::PointerType *T, QualType QT) const;
```
https://reviews.llvm.org/D28814
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