logan added inline comments.
================
Comment at: include/unwind.h:224
@@ +223,3 @@
+
+static __inline__ uintptr_t _Unwind_GetGR(struct _Unwind_Context *context,
+ int index) {
----------------
asl wrote:
> logan wrote:
> > asl wrote:
> > > Why can't we simply make them static functions of UnwindLevel1.c for
> > > EHABI case?
> > They can't be //static// functions of UnwindLevel1.c because they will be
> > called from the other source code (e.g. libc++abi calls these functions.)
> > If they are declared as static functions in UnwindLevel1.c, then the other
> > source code can't access these functions.
> >
> > We can't declare these functions as extern and define these functions in
> > UnwindLevel1.c either. If we do so, the source code including this header
> > and using these functions will be compiled to object files with external
> > symbols (undefined references) to these functions. This means that these
> > symbols should be available to the linkers. However, libgcc does not
> > provide these symbols. If we are building libc++abi with libgcc without
> > libunwinder, then we will encounter the following link error:
> >
> > libcxxabi/src/cxa_personality.cpp:(.text+0x3c): undefined reference to
> > `_Unwind_SetGR'
> > (... and etc ...)
> >
> > This is the reason why these functions must be inlined. AFAICT, both the
> > unwind.h from gcc or clang (`lib/Header/unwind.h`) are following the same
> > practice.
> I see. My biggest concern is the use of LIBCXXABI_ARM_EHABI define. We need
> to resolve this beforehand, because currently we're having a cyclic
> dependency between libunwind and libcxxabi via __cxxabi_config.h. I'd simply
> fold it inside libwunwind (or introduce __libunwind_config.h)
OK. I think I will simply copy the `ifdef`s from `__cxxabi_config.h` since
they are simple. Will update the patch soon.
My long term plan is to merge this `unwind.h` with the one in the clang
repository. And then, update libc++abi so that we can use the `unwind.h` from
the compiler (both `clang` and `gcc`) directly.
http://reviews.llvm.org/D11190
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