llvm dev - Sep 2018 - how to determine abi alignment of function based on its type?

The following assertion is tripping when I do LLVMABIAlignmentOfType on a
function type:

#4  0x0000000005b67fc4 in llvm::DataLayout::getAlignment (this=0xa0bb960,
Ty=0xa0bee58,
    abi_or_pref=true) at
/home/andy/downloads/llvm_release_70/lib/IR/DataLayout.cpp:672
672      assert(Ty->isSized() && "Cannot getTypeInfo() on a type
that is
unsized!");

(gdb) p Ty->dump()
void ()

Shouldn't this type be sized? Is this a bug?

As a workaround, I have to assume that all functions are only 1-byte
aligned, but that doesn't seem sound. Is it possible to find out the ABI
alignment of a function?

Regards,
Andrew
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Hi Andrew,

On Sun, 16 Sep 2018 at 16:17, Andrew Kelley via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> (gdb) p Ty->dump()
> void ()
>
> Shouldn't this type be sized? Is this a bug?
That's a function taking no parameters and returning void. Notably
*not* a pointer to such a function. So it could have pretty much any
size depending on the function body (well, if we actually modelled the
size, which we don't).
> As a workaround, I have to assume that all functions are only 1-byte
aligned, but that doesn't seem sound.
Minimum function alignment is specified in C++ via TargetLoweringBase
(and hence TargetLowering).

Cheers.

Tim.