[ObjC] Create a shared ObjC processor for Macho and DSC views #6297
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`BackingCache` now tracks the `dyld_cache_mapping_info` for its mappings so it has access to the memory protections for the region. This means it can avoid marking some regions as containing code when they don't, reducing the amount of analysis work that has to be done. Using `dyld_cache_mapping_info` also makes references to mappings easier to understand due to its named fields vs the nested `std::pair`s that were previously in use.
Find the relative selector base address in the Objective-C optimization data pointed to by the shared cache header, rather than via `__objc_scoffs`. This is only present on iOS, and not for every iOS version that encodes selectors via direct offsets. This also includes some related improvements: 1. Direct selectors get their own pointer type so they're rendered correctly in the view. 2. Method lists encoded as lists of lists are now handled. 3. The `dyld_cache_header` type added to the view is truncated to the length in the loaded cache. This ensures it is applied to the view. 4. A couple of methods that process method IMPs and selectors are updated to check whether the address is valid before attempting to process them. They would otherwise fail by throwing an exception if they proceed, but checking for validity is quicker and makes exception breakpoints usable.
…eser, fix compilation issue on linux
Both the Macho and DSC views need to process Objective-C but have separate processor classes. It would appear that the DSC version was largely a copy and paste of the Macho view one, with some modifications. The majority of code overlaps between the 2 so it doesn't make sense to maintain 2 and copy and paste improvements/fixes between them. This commit fixes that by creating a base Objective-C processor that contains the shared code. View specific code is implemented in the respective subclasses for the views. Although there is very little view specific code for each.
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NOTE: this builds on top of #6192
Both the Macho and DSC views need to process Objective-C but have separate processor classes. It would appear that the DSC version was largely a copy and paste of the Macho view one, with some modifications. The majority of code overlaps between the 2 so it doesn't make sense to maintain 2 and copy and paste improvements/fixes between them.
This PR fixes that by creating a base Objective-C processor that contains the shared code. View specific code is implemented in the respective subclasses for the views. Although there is very little view specific code for each.
I think something similar would be worth doing for the Objective-C workflow as I believe things like the
objc_msgSendworkflow stuff is being shared/copied and pasted from there. However I'm not sure how to do that myself as I'm unsure the desired coding structure because it would probably require that plugin to be imported into this API repo.