[PATCH] Allocate stack storage for .block_descriptor and captured self.

[John McCall]

On Mar 7, 2013, at 10:11 AM, Adrian Prantl <aprantl at apple.com> wrote:
> I think there is a bug in the existing code in lib/CodeGen/Blocks.cpp:1181
> 
>   unsigned align = getContext().getDeclAlign(variable).getQuantity();
> 
>    llvm::AllocaInst *alloca =
>      CreateMemTemp(variable->getType(), "block.captured-const");
>    alloca->setAlignment(align);
> 
>    Builder.CreateStore(capture.getConstant(), alloca, align);
> 
>                                                       ^^^^^
> 
> The third argument of IRBuilder::CreateStore() is the “volatile” flag.
> http://llvm.org/doxygen/classllvm_1_1IRBuilder.html
> 
> I assume that “align” is usually nonzero — so it would likely output a "store volatile". Do you think that’s unintentional and it’s safe to replace it with false? Or is the volatile modifier needed here?

It's probably supposed to be a call to a CreateAlignedStore.  The volatility is unintentional.

John.