Can't memset a zeropage array about llvm-mos

[asiekierka]

After #369 , this leads to a crash due to an illegal COPY being emitted where an 8-bit GPR is assigned to RS1.

Essentially, pointers need to be automatically promoted between address spaces for this to work correctly - for now, after said PR gets merged, you can work around this by casting manually: memset((char*) intthing, 42, 10);.

I'm not sure what the correct way to fix this is.

[mysterymath]

@asiekierka , if you get around to this, take a look at isAddressSpaceSupersetOf in clang/AST/Type.h. I think that logic determines whether an implicit conversion between address spaces is attempted.

EDIT: It doesn't look like there's any target plumbing for this... concerning. We may need to create this ex nihilo. We should see if that would even help first.

[asiekierka]

That's fine. Target plumbing is handled elsewhere, just by virtue of the SupersetOf function being of the "assume explicit conversion if not" kind.

However, that method is never called to check for a difference between the zero-page pointer type and non-zero-page pointer type in the first place. I'm worried we may be brushing up on the limits of Clang's address space handling (mostly built to satisfy AMD's OpenCL needs).