[PATCH] D56206: Introduce `RemoteAddressSpaceView` and `VMReadContext`.

[Dan Liew via Phabricator via llvm-commits]

delcypher added inline comments.


================
Comment at: lib/sanitizer_common/sanitizer_remote_address_space_view.h:27
+ private:
+  static VMReadContext* vmrc;
+  static void* internal_read(uptr target_address, uptr size, bool writable) {
----------------
vitalybuka wrote:
> Why all these stuff needs to be static?
@vitalybuka Because the allocators don't receive an instance of `RemoteAddressSpaceView`, they receive the type as a template parameter (e.g. SizeClassAllocator64). This design choice means that everything in an implementation of the `AddressSpaceView` interface (i.e. `LocalAddressSpaceView` and `RemoteAddressSpaceView`) needs to be static.

To implement `RemoteAddressSpaceView` we **have to store some state**. All of this state and the read operations are encapsulated in the `VMReadContext` object. We cannot store any of this state inside the allocators because that could change the data-layout.

This design is not thread-safe of course but for allocator enumeration on Darwin will only ever be doing that in a single thread anyway.


Repository:
  rCRT Compiler Runtime

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56206/new/

https://reviews.llvm.org/D56206