From 36b758bb4b5056ef77b08624186b8dd6e9e707c6 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i@maskray.me>
Date: Sun, 23 Sep 2018 11:16:35 -0700
Subject: [PATCH] Update local clang+llvm build instructions

---
 Build.md | 51 +++++++++++++++++++++++++++++----------------------
 1 file changed, 29 insertions(+), 22 deletions(-)

diff --git a/Build.md b/Build.md
index bfd552a..73eb501 100644
--- a/Build.md
+++ b/Build.md
@@ -79,47 +79,54 @@ If using Windows the automatically downloaded LLVM binaries are 64-bit; you shou
 
 ## Link against clang+llvm libraries compiled from source
 
-MaskRay's config (building trunk LLVM at `~/Dev/llvm/release/`):
+* `include/llvm/Config/config.h`
+* `include/clang/Config/config.h`
+* `lib/libclangIndex.so`
+* `lib/libLLVM{Support,...}.so` or `lib/libLLVM{Support,...}.a` or `lib/libLLVM.so`
+
+MaskRay's config (building trunk LLVM at `~/llvm/Release/`):
 
 ```
-cd ~/Dev
+cd
 git clone https://git.llvm.org/git/llvm.git
 cd llvm/tools
 git clone https://git.llvm.org/git/clang.git
-cd ~/Dev
-# create a build directory named `release/`
-cmake -H. -Brelease -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_C_COMPILER=clang -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DBUILD_SHARED_LIBS=ON -DLLVM_ENABLE_LLD=ON -DLLVM_INCLUDE_EXAMPLES=OFF -DLLVM_INCLUDE_TESTS=OFF -DLLVM_INCLUDE_GO_TESTS=OFF -DLLVM_INCLUDE_DOCS=OFF -DLLVM_TARGETS_TO_BUILD=X86 -DLLVM_USE_SPLIT_DWARF=On -DLLVM_OPTIMIZED_TABLEGEN=On
+cd ~/llvm
+# create a build directory named `Release/`
+cmake -H. -BRelease -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_C_COMPILER=clang -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DBUILD_SHARED_LIBS=ON -DLLVM_ENABLE_LLD=ON -DLLVM_TARGETS_TO_BUILD=X86
+ninja -C Release clangIndex clangTooling
 ```
 
-Remove `LLVM_ENABLE_LLD` if don't have lld (a much faster linker than bfd/gold) installed  
-Remove `BUILD_SHARED_LIBS` if you want to build static libraries (`libclangDriver.a` `libLLVMSupport.a`, note `libclang.so` is still a shared object)
+* Remove `LLVM_ENABLE_LLD` if you don't have lld (a much faster linker than bfd/gold) installed
+* Remove `BUILD_SHARED_LIBS` if you want to build static libraries (`libclangIndex.a`) instead
 
-Then build ccls:
+Then build ccls with `-DSYSTEM_CLANG` and `-DCMAKE_PREFIX_PATH`:
 
 ```zsh
-cmake -H. -Brelease -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_EXE_LINKER_FLAGS=-fuse-ld=lld -DCMAKE_EXPORT_COMPILE_COMMANDS=On -DSYSTEM_CLANG=On -DCMAKE_PREFIX_PATH="$HOME/Dev/llvm/release;$HOME/Dev/llvm/release/tools/clang;$HOME/Dev/llvm;$HOME/Dev/llvm/tools/clang"
-cmake --build release
+cd ~/ccls
+cmake -H. -BRelease -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_EXE_LINKER_FLAGS=-fuse-ld=lld -DSYSTEM_CLANG=On -DCMAKE_PREFIX_PATH="$HOME/llvm/Release;$HOME/llvm/Release/tools/clang;$HOME/llvm;$HOME/llvm/tools/clang"
+ninja -C Release
 ```
 
-There are 4 directories specified in `CMAKE_PREFIX_PATH`:
+`-DCMAKE_PREFIX_PATH=` is a `;`-separated list where you can find:
 
-* `Dev/llvm`: llvm source
-* `Dev/llvm/tools/clang`: clang source (`git clone https://git.llvm.org/git/clang.git`)
-* `Dev/llvm/release`: build directory. `include/` contains some generated llvm header files
-* `Dev/llvm/release/tools/clang`: part of the build directory. `include/` contains some generated clang header files
+* `llvm`: llvm source
+* `llvm/tools/clang`: clang source (`git clone https://git.llvm.org/git/clang.git`)
+* `llvm/Release`: build directory. `include/` contains generated llvm header files, e.g. `include/llvm/Config/config.h`
+* `llvm/Release/tools/clang`: build directory. `include/` contains generated clang header files, e.g. `include/clang/Config/config.h`
 
 The cmake build system is expected to find these files:
 
 ```
 # generated clang+llvm header files
-~/Dev/llvm/release/include/llvm/Config/config.h
-~/Dev/llvm/release/tools/clang/include/clang/Config/config.h
-# libclang
-~/Dev/llvm/release/lib/libclang.so
+~/llvm/Release/include/llvm/Config/config.h
+~/llvm/Release/tools/clang/include/clang/Config/config.h
+# libclangIndex.so
+~/llvm/Release/lib/libclangIndex.so
 # -resource-dir
-~/Dev/llvm/release/lib/clang/7.0.0
+~/llvm/release/lib/clang/7.0.0
 # clang+llvm libraries
-~/Dev/llvm/release/lib/libclangDriver.so
-~/Dev/llvm/release/lib/libLLVMSupport.so
+~/llvm/release/lib/libclangDriver.so
+~/llvm/release/lib/libLLVMSupport.so
 ...
 ```