Update mailing list post URL

[emaste]

Summary

http://lists.llvm.org/pipermail/llvm-dev/2013-April/061768.html is 404. Based on context http://lists.llvm.org/pipermail/llvm-dev/2013-April/061737.html seems like the intended list posting.

[andrew.w.kaylor]

It looks to me like you are probably correct about the intended mailing list post, but it's still not particularly helpful. It would be nice to have a reference to a primary source, but this is the best I could find:

https://opensource.apple.com/source/libunwind/libunwind-35.3/src/UnwindLevel1-gcc-ext.c

In any event, your change seems like a step forward so lgtm.

[emaste]

In D27965#629005, @andrew.w.kaylor wrote:

It looks to me like you are probably correct about the intended mailing list post, but it's still not particularly helpful. It would be nice to have a reference to a primary source, but this is the best I could find:

https://opensource.apple.com/source/libunwind/libunwind-35.3/src/UnwindLevel1-gcc-ext.c

Yes, I couldn't find a primary source. It seems the expected behaviour is not documented by GCC, but GCC's API is the de-facto correct one.

My guess is that the Apple API is just a bug. I've modified libunwind in FreeBSD to implement GCC's libgcc API: https://svnweb.freebsd.org/changeset/base/310365

[emaste]

this is the best I could find:

https://opensource.apple.com/source/libunwind/libunwind-35.3/src/UnwindLevel1-gcc-ext.c

Oh, good point on this file: I also added a reference to its canonical location in the llvm tree.

llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp

 }
 
 // This implementation handles frame registration for local targets.
 // Memory managers for remote targets should re-implement this function
 // and use the LoadAddr parameter.
 void RTDyldMemoryManager::registerEHFramesInProcess(uint8_t *Addr,
                                                     size_t Size) {
   // On OS X OS X __register_frame takes a single FDE as an argument.
-  // See http://lists.llvm.org/pipermail/llvm-dev/2013-April/061768.html
+  // See http://lists.llvm.org/pipermail/llvm-dev/2013-April/061737.html
+  // and projects/libunwind/src/UnwindLevel1-gcc-ext.c.
   const char *P = (const char *)Addr;
   const char *End = P + Size;
   do  {
     P = processFDE(P, false);
   } while(P != End);
 }
 
 void RTDyldMemoryManager::deregisterEHFramesInProcess(uint8_t *Addr,