[clang] [llvm] [ASAN] For Asan instrumented global, emit two symbols, one with actual size and other with instrumented size. (PR #70166)

[Mitch Phillips via cfe-commits]

hctim wrote:

> > It's my understanding your problem is that you are asan-trapping on the redzones when you copy data to/from the device. Is it possible instead to just make those copy-from and copy-to functions in the runtime `__attribute__((no_sanitize("address")))` and copy the padding as well?
> 
> Yes it is possible, but it would result in bugs being hidden...the very bugs that ASAN is meant to catch. This is not an acceptable option for us.

Only bugs in the `copy_from_` and `copy_to_` functions though (which should be pretty clear)?

--

Alright, let's give this a crack. I'll leave some comments here and on #68865, but let's not worry about potential unknown problems and we can see what shakes out once we actually submit the patches.

https://github.com/llvm/llvm-project/pull/70166