[BoundsSafety] `__single` pointers are not null-checked.

[zyedidia]

In the description of the -fbounds-safety feature, it says "Dereferencing a __single pointer is allowed but it requires a null check."

However, in my testing of the feature preview (implemented here: https://github.com/swiftlang/llvm-project/tree/stable/20240723) it seems like there is no null check performed. I tried compiling the following program:

#include <ptrcheck.h>

int foo(int *__single p) {
  return *p;
}

int bar(int *__counted_by_or_null(1) p) {
  return *p;
}

$ clang -fbounds-safety -S test.c -O2 -target aarch64

This gives the following assembly (abbreviated):

foo:
	ldr	w0, [x0]
	ret

bar:
	cbz	x0, .LBB1_3
	add	x8, x0, #4
	cmp	x8, x0
	b.lo	.LBB1_3
	ldr	w0, [x0]
	ret
.LBB1_3:
	brk	#0x5519

bar contains a check, but foo has no check and directly dereferences the __single input pointer. Please let me know if I am using the wrong version or doing something incorrect. Thank you.