This removes all support for GC mode.
This was deprecated by Apple in OS X 10.8 (2012) and never supported in
iOS. Very little code ever tried to use it with this runtime.
It's gone from the build system already.
We now correctly handle ivars that overlap with the end of what the
compiler thinks is the start of the superclass and bitfields at the
start of a class.
Clang rounds up the size of a class to the size of a word. If the first
instance variable in a subclass has a field that has smaller alignment
requirements than a word, it is generated with a negative offset,
indicating that it belongs in the space allocated for the parent.
This did not work at all with the code we have for recomputing instance
variable layouts, which uses only the size and the alignment.
Fixes#96
Add a flag to indicate that instance variables have an extended type
encoding.
Remove the alignment field and replace it with 6 bits from the flags
field. We only support power of two alignments, so we may as well store
them in log form, which means we can save a field. Note that this
doesn't actually save us any space except on 32-bit platforms, because
alignment means that we end up with extra padding at the end of the
struct.
Several of the structures now end with an array of structures that may
have other fields added to them that the runtime doesn't know about yet
by a compiler. Rather than indexing into them directly, we must call an
accessor to find the correct address.
A few of the places where accesses were replaced were in functions where
it is safe because they only deal with versions of the structures that
are dynamically allocated (and will therefore have the correct size).
This was done to simplify future auditing: these fields should be
accessed directly only from the accessor functions in the header and
from the upgraders (currently in legacy.c).
Also fix a few bugs where the sizes weren't being filled in.
We're now using a new class and category structure and auto-upgrading the old ones. Other changes:
- The Ivar structure now points to the ivar offset variable, so we can more easily find it.
- Categories can now add properties.
correct.
Instance variables are not normally zero-sized, but some are. Examples
include zero-length arrays at the end of a class, and bitfields.
Fixes#30Fixes#31
When we were trying to get or set an ivar on a class that had
no ivars defined, we'd dereference a NULL ivar list while
determining the ownership qualifier.
The new structure has extra fields for alignment and flags (e.g.
ownership).
Old structures are auto-upgraded at load time, so the rest of the code
can assume the presence of the new structure type.
David Chisnall
David Chisnall
David Chisnall
Niels Grewe
theraven