This change set incorporates a number of changes that all needed to
happen together:
* The imp is now the first field of the `objc_method` structure. This
makes it possible to extend the structure without breaking anything
that relies on being able to access the IMP.
* There is no owner in the slot, so we must use other mechanisms for
determining the owner of a method (e.g. whether the same method appears
in the superclass)
* Again, because there is no owner in the slot, we can't use this as a
fast path for finding the C++ construct / destruct methods. These are
now cached in the class structure when they are found.
* The version field is gone from the slot and now we provide a global
version. This is based on the observation that method replacements
are relatively infrequent and the overhead of invalidating all method
caches is cheaper than adding extra state for every (class, method)
pair.
* A number of the runtime functions are simplified because replacing
the IMP in a `Method` now implicitly updates the dtable.
Some applications still include the old objc-class.h header expecting
to obtain the declarations contained in objc/message.h and
objc/runtime.h nowadays. This commit adds this header to achieve
out-of-the-box compatibility with these applications.
Some applications still include the old objc-runtime.h header expecting
to obtain the declarations contained in objc/message.h and
objc/runtime.h nowadays. This commit adds this header to achieve
out-of-the-box compatibility with these applications.
at the start of the structure, making it easier to change the layout in
the future.
Also clean up the growth of various fields and consolidate some of the
metadata into a pointer to the `struct objc_method`.
An interesting feature of the AArch64 ABI simplifies this code relative to other platforms. AArch64 reserves an extra register (x8) for the address of struct returns, giving the
clang trunk if -fobjc-runtime-1.7 is specified and provides significantly
better interoperability with foreign exceptions.
Note: Most of the exception tests will not pass with gcc or clang < 3.3. They
test things that are impossible to implement quite correctly with the
GCC-compatible exception ABI.
Also updated the release notes to reflect recent improvements.
Weak references are still not supported, but code that doesn't use them (i.e. any code that wants to be compatible with OS X 10.6) will work fine.
The current implementation is VERY inefficient and has a large number of missed optimisation opportunities: this is the 'make it right' phase, and should be almost equivalent to explicit retain / release code.
registered to be copied on heap assignment. By default, this is just
_NSConcreteStackBlock. Other classes can be registered (LanguageKit should
register BlockClosure to make sure that Smalltalk works).
Fred: This makes the stuff that we discussed briefly at FOSDEM possible in GC
mode: We can allocate a GSStackEvent subclass of NSEvent on the stack. If it
implements a -copy method that returns an NSEvent and is registered with the
runtime in this way, then any code that assigns it anywhere on the heap will
end up implicitly creating a heap copy.
- Add objc_gc_collectable_address() to determine whether a pointer is managed
by the GC
- If LIBOBJC_CANARIES is set (optionally to a random number seed) then store a
canary value after every allocation returned by
objc_gc_allocate_collectable() and, when it is finalised, check that the
canary has not been modified, aborting if it has. This catches some
heap-buffer overflows, and currently causes GNUstep to abort.
- If LIBOBJC_LOG_ALLOCATIONS is set to a file name, log all GC-managed
allocations to that file. This gives something like malloc_history on OS X.
- objc_memmove_collectable() now guarantees that all copied pointers remain
visible to the GC at all times (which was the point of the function - the
original implementation was just a quick stub).
David Chisnall
David Chisnall
Zenny Chen
Daniel Ferreira
Daniel Ferreira
David Chisnall
theraven
thebeing