smeenai added inline comments.
================
Comment at: lib/CodeGen/CGObjCMac.cpp:7457-7460
CGObjCNonFragileABIMac::GetEHType(QualType T) {
// There's a particular fixed type info for 'id'.
if (T->isObjCIdType() || T->isObjCQualifiedIdType()) {
+ if (CGM.getTriple().isWindowsMSVCEnvironment())
----------------
smeenai wrote:
> rjmccall wrote:
> > smeenai wrote:
> > > rjmccall wrote:
> > > > rnk wrote:
> > > > > @rjmccall how should this be organized in the long run? At this
> > > > > point, the naming seems totally wrong. Is the non-fragile ABI sort of
> > > > > the canonical way forward for Obj-C, i.e. it's what a new platform
> > > > > would want to use to best stay in sync with the future of obj-c?
> > > > For Darwin, yes, absolutely.
> > > >
> > > > I think this method should probably just completely delegate to the
> > > > `CGCXXABI` using a new `getAddrOfObjCRTTIDescriptor` method.
> > > To be clear, you'd want the entirety of the EHType emission logic to be
> > > shifted to CGCXXABI? I think that would make sense, and I can look into
> > > it.
> > Right.
> Sorry, getting back to this now.
>
> What did you have in mind for handling the different Obj-C runtimes? Were you
> envisioning the new getAddrOfObjCRTTIDescriptor method supporting just the
> non-fragile Mac ABI or all of them?
Looked into this more. ItaniumRTTIBuilder already has a
BuildObjCObjectTypeInfo, which confused me for a bit until I realized it's only
ever used for the fragile ABI, and even then only when using C++ try/catch
(instead of Obj-C style @try/@catch), which is a bit strange. Everything else
does its own thing.
From what I've been able to make out, these are the current possibilities for
generating Obj-C RTTI for the Itanium ABI:
* Fragile macOS runtime using Obj-C @try/@catch: doesn't actually seem to
generate any RTTI as far as I can tell, and uses `objc_exception_match` instead.
* Fragile macOS runtime using C++ try/catch: goes through
`ItaniumRTTIBuilder::BuildObjCObjectTypeInfo`, which generates C++ compatible
RTTI referencing a C++ class type info.
* Non-fragile macOS runtime: generates its own C++ compatible RTTI referencing
`objc_ehtype_vtable`.
* GNUStep for Objective-C++: generates its own C++ compatible RTTI referencing
`_ZTVN7gnustep7libobjc22__objc_class_type_infoE`.
* All other GNU runtimes (including GNUStep for Objective-C): just uses the
identifier name string of the interface as its "RTTI".
I think it makes sense to only have the new `getAddrOfObjCRTTIDescriptor`
method handle the non-fragile macOS runtime for now, and perhaps
`ItaniumRTTIBuilder::BuildObjCObjectTypeInfo` should be renamed (or at least
have a comment added) to indicate that it's only used for the fragile macOS
runtime when catching an Obj-C type with C++ catch.
Repository:
rC Clang
https://reviews.llvm.org/D47233
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