How to build clang with clang?

Question

I allready build clang(3.2) with MSVC and MinGW succesfully. But I think it's not the "purely" clang. So could someone give me some instructions or materials about how to use clang to build clang(Windows/Linux)? And could we use clang indepently(Not depent on GCC or MSVC). Thanks all!

Answer 1

Well get an older version of clang like 3.1. (You can pretty much install any version that comes precompiled for your OS)

Get the sources for a newer version like 3.2.

Then (i like cmake+ninja ( http://clang.llvm.org/docs/HowToSetupToolingForLLVM.html ))

if you unpacked llvm source to ~/llvm_source/llvm

cd ~/llvm_source
mkdir build
cd build
CXX=clang++ CC=clang cmake -G Ninja ../llvm -DCMAKE_BUILD_TYPE=Release
ninja

If you want it for make

CXX=clang++ CC=clang cmake ../llvm -DCMAKE_BUILD_TYPE=Release
make

Thats it.

Have fun.

Answer 2

The current method (as of 27th Feb 17') seems to be as follows,

cmake -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++  $LLVM_SRC_DIR # -G Ninja

Where CMAKE_C_COMPILER and CMAKE_CXX_COMPILER are CMake variables define by -D . Somehow, these variables don't appear in llvm_src/CMakeLists.txt

Answer 3

When making clang with clang, you will coincide with the already existing definitions of builtin functions and those which yet to be defined again - the compiler gets into troubles of doubled consciousness!!! I've got the next:

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clang/Basic/BuiltinsX86.def:1907:1: note: previous definition is here TARGET_HEADER_BUILTIN(_ReadWriteBarrier, "v", "nh", "intrin.h", ALL_MS_LANGUAGES, "")

clang\CodeGen\code\CGBuiltin.cpp:638:1: error: reference to '_bittest' is ambiguous BitTest BitTest::decodeBitTestBuiltin(unsigned BuiltinID) { ^ include\winnt.h:2236:17: note: expanded from macro 'BitTest' #define BitTest _bittest ^ include\psdk_inc/intrin-impl.h:1707:16: note: candidate found by name lookup is '_bittest' __buildbittest(_bittest, __LONG32, "l", "I") ^ clang\CodeGen\code\CGBuiltin.cpp:620:8: note: candidate found by name lookup is '(anonymous namespace)::_bit test' struct BitTest { ^ include\winnt.h:2236:17: note: expanded from macro 'BitTest' #define BitTest _bittest ^ clang\CodeGen\code\CGBuiltin.cpp:696:45: error: reference to '_bittest' is ambiguous BitTest BT, ^ include\winnt.h:2236:17: note: expanded from macro 'BitTest' #define BitTest _bittest ^ include\psdk_inc/intrin-impl.h:1707:16: note: candidate found by name lookup is '_bittest' __buildbittest(_bittest, __LONG32, "l", "I")

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And so on and on ...