libunwind: make __{de,}register_frame compatible with libgcc API
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Authored by emaste on Dec 20 2016, 2:19 PM.

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rG96ac81cdf020: Reapply r310365 (by emaste):
rS363774: Reapply r310365 (by emaste):
rS310365: libunwind: make __{de,}register_frame compatible with libgcc API

Summary

The libgcc __register_frame and __deregister_frame functions take a pointer to a set of FDE/CIEs, terminated by an entry with length = 0.
In Apple's implementation the pointer is assumed to be to a single FDE. I suspect this is just a bug.

Make us compatible with libgcc instead.

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rS FreeBSD src repository - subversion

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emaste updated this revision to Diff 23140.Dec 20 2016, 2:19 PM

emaste retitled this revision from to libunwind: make __{de,}register_frame compatible with libgcc API.

emaste updated this object.

emaste edited the test plan for this revision. (Show Details)

emaste added a reviewer: dim.

dim added inline comments.Dec 20 2016, 5:09 PM

contrib/llvm/projects/libunwind/src/UnwindLevel1-gcc-ext.c
231 ↗	(On Diff #23140)	This might not be alignment-safe. Maybe we can reuse some get() macro here? Otherwise, we should use memcpy. Similar for the following char-to-larger-type pointer casts.
272 ↗	(On Diff #23140)	Aren't we missing an `#endif` here?

Fix typos and missing #endif

emaste added inline comments.Dec 20 2016, 7:05 PM

contrib/llvm/projects/libunwind/src/UnwindLevel1-gcc-ext.c
231 ↗	(On Diff #23140)	I cribbed from LLVM's RTDyldMemoryManager.cpp, and I think this is indeed worth improving. Right now though libunwind is used only on amd64 / i386 / arm64.