Rename *.c to *.cpp to generate unwind tables for these functions.

[logan]

Summary

If we compile these *.c files with arm-linux-gnueabi-gcc, gcc won't
generate the unwind table by default. As the result, the _Unwind_Backtrace
can't unwind through itself.

This change fix the problem by renaming *.c to *.cpp.

(p.s. This is the 5/6 patch to fix the backtrace_test and libgcc support.)

[rengolin]

It used to always generate the EHABI tables, even in C mode, so I'm surprised it doesn't any more.

Nevertheless, I think we better use a flag to emit the tables rather than change the language, as C++isms could creep in and we want this code as simple as possible.

cheers,
--renato

[jroelofs]

We had a flag for it at one point. How are you building this, @logan... cmake, or buildit?

[logan]

I am using cmake and clang 3.5.

An alternative solution is to add -funwind-tables to CFLAGS.

I guess that it is due to the fact that these C functions are considered as nothrow.

[jroelofs]

Yeah, I think it would be best to add -funwind-tables (back?) to the CFLAGS.

[logan]

OK. Please refer to D7099 for the -funwind-tables change instead.

src/Unwind/CMakeLists.txt

 # Get sources
 set(LIBUNWIND_SOURCES
   libunwind.cpp
   Unwind-EHABI.cpp
-  UnwindLevel1.c
-  UnwindLevel1-gcc-ext.c
-  Unwind-sjlj.c
+  UnwindLevel1.cpp
+  UnwindLevel1-gcc-ext.cpp
+  Unwind-sjlj.cpp
 )
 
 append_if(LIBUNWIND_SOURCES APPLE Unwind_AppleExtras.cpp)
 
 set(LIBUNWIND_ASM_SOURCES
   UnwindRegistersRestore.S
   UnwindRegistersSave.S
 )

src/Unwind/Unwind-sjlj.cpp

-//===--------------------------- Unwind-sjlj.c ----------------------------===//
+//===-------------------------- Unwind-sjlj.cpp ---------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //
 //  Implements setjump-longjump based C++ exceptions

src/Unwind/UnwindLevel1-gcc-ext.cpp

-//===--------------------- UnwindLevel1-gcc-ext.c -------------------------===//
+//===-------------------- UnwindLevel1-gcc-ext.cpp ------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //
 //  Implements gcc extensions to the C++ ABI Exception Handling Level 1.

src/Unwind/UnwindLevel1.cpp

-//===------------------------- UnwindLevel1.c -----------------------------===//
+//===------------------------ UnwindLevel1.cpp ----------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //
 // Implements C++ ABI Exception Handling Level 1 as documented at: