vsk added a comment.

In https://reviews.llvm.org/D34299#787795, @arphaman wrote:

> It looks like if we have a function without the `return` (like the sample 
> below), we will pass in a `0` as the location pointer. This will prevent a 
> report of a runtime error as your compiler-rt change ignores the location 
> pointers that are `nil`. Is this a bug or is this the intended behaviour?
>
>   int *_Nonnull nonnull_retval1(int *p) {
>   }
>


This is the intended behavior (I'll add a test). Users should not see a "null 
return value" diagnostic here. There is another check, -fsanitize=return, which 
can catch this issue.

@filcab --

> Splitting the attrloc from the useloc might make sense since we would be able 
> to emit attrloc just once. But I don't see why we need to store/load those 
> pointers in runtime instead of just caching the Constant* in CodeGenFunction.

The source locations aren't constants. The ubsan runtime uses a bit inside of 
source location structures as a flag. When an issue is diagnosed at a 
particular source location, that bit is atomically set. This is how ubsan 
implements issue deduplication.

> I'd also like to have some asserts and explicit resets to nullptr after use 
> on the ReturnLocation variable, if possible.

Resetting Address fields in CodeGenFunction doesn't appear to be an established 
practice. Could you explain what this would be in aid of?


https://reviews.llvm.org/D34299



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