ObjC/ObjC++ - implementation of non-trivial property accessors

["Nicola Pero" <nicola dot pero at meta-innovation dot com>]

This patch implements synthesizing accessors for Objective-C / Objective-C++
properties which are 'atomic', 'retain' or 'copy'. :-)

The existing code would only work for 'assign, nonatomic' properties, in which
case the getter/setter methods simply access the instance variable directly.

The new code can generate more sophisticated getter/setter methods that call into
helper functions in the Objective-C runtime.  For the next runtime these are
objc_getProperty(), objc_setProperty() and objc_copyStruct().  In the GNU runtime
I used identical functions, with the exception of the last one, objc_copyStruct(), 
which seems to have been designed wrong (in a messy way as it requires two locks instead
of one to protect the property because the runtime is unable to determine which 
argument is the property to protect and which argument is the external variable (!)), 
and I couldn't see any reason to reproduce the same error in the GNU runtime, 
where I used two separate functions (designed correctly) instead, called 
objc_getPropertyStruct() and objc_setPropertyStruct(), requiring only one lock 
to protect the property (as expected).  These helpers are part of the runtime ABI,
so the GNU runtime doesn't have to be the same as the next runtime - users never
see these functions directly.  But because they are part of the ABI, it's not
necessarily easy to change them later once you add them.  I hope ours are good. :-)

Testcases are included; they all pass with the GNU runtime.  They should work with 
the next runtime too if garbage collection is disabled and the old ABI is used, as the
only difference is the usage of objc_copyStruct instead of objc_getPropertyStruct
and objc_setPropertyStruct (anyway if there are any issues, we have 2 months
to fix them). :-)

Ok to commit to trunk ?

Thanks

In gcc/objc/:
2010-10-31  Nicola Pero  <nicola.pero@meta-innovation.com>

        Implemented Objective-C 2.0 property accessors.
        * objc-act.h (enum objc_tree_index): Added OCTI_GET_PROPERTY_DECL,
        OCTI_SET_PROPERTY_DECL, OCTI_COPY_STRUCT_DECL,
        OCTI_GET_PROPERTY_STRUCT_DECL and OCTI_SET_PROPERTY_STRUCT_DECL.
        (objc_getProperty_decl): New.
        (objc_setProperty_decl): New.
        (objc_copyStruct_decl): New.
        (objc_getPropertyStruct_decl): New.
        (objc_setPropertyStruct_decl): New.
        * objc-act.c (build_objc_property_accessor_helpers): New.
        (synth_module_prologue): Call
        build_objc_property_accessor_helpers.
        (lookup_ivar): New.
        (objc_synthesize_getter): Implemented synthesizing getters that
        work with properties that are not nonatomic, assign properties.
        (objc_synthesize_setter): Implemented synthesizing setters that
        work with properties that are not nonatomic, assign properties.

In gcc/testsuite/:
2010-10-31  Nicola Pero  <nicola.pero@meta-innovation.com>

        Implemented Objective-C 2.0 property accessors.
        * objc.dg/property/at-property-6.m: Use nonatomic properties to
        avoid testing more complex accessors in this testcase which is not
        about them.
        * objc.dg/property/at-property-7.m: Same change.
        * objc.dg/property/at-property-8.m: Same change.
        * objc.dg/property/at-property-9.m: Same change.
        * objc.dg/property/at-property-10.m: Same change.
        * objc.dg/property/at-property-11.m: Same change.
        * obj-c++.dg/property/at-property-6.mm: Same change.
        * obj-c++.dg/property/at-property-7.mm: Same change.
        * obj-c++.dg/property/at-property-8.mm: Same change.
        * obj-c++.dg/property/at-property-9.mm: Same change.
        * obj-c++.dg/property/at-property-10.mm: Same change.
        * obj-c++.dg/property/at-property-11.mm: Same change.
        * objc.dg/property/at-property-12.m: New.
        * objc.dg/property/at-property-13.m: New.
        * obj-c++.dg/property/at-property-12.mm: New.
        * obj-c++.dg/property/at-property-13.mm: New.

Attachment: patch.txt
Description: Text document