This project is my attempt to explore LLVM world, and create a plugin for it just for fun. It doesn't do any help to me in real life for now.
- CLion / VSCode / Command Line
- CMake
LLVM14 is installed via homebrew, maybe I should build one.
# install llvm14 using brew
brew install llvm@14
export PATH="/opt/homebrew/opt/llvm@14/bin:$PATH"
# setup CXX & CC，CMAKE 会使用这两个环境变量
export CXX=/opt/homebrew/opt/llvm@14/bin/clang++
export CC=/opt/homebrew/opt/llvm@14/bin/clang
### 创建一个 build 文件夹
mkdir cmake-build-debug && cd cmake-build-debug
cmake -DCMAKE_BUILD_TYPE=Debug ..
## build whenever source code changes, which will create TestLLVM01Lib.dylib under current folder
cmake --build .
## compile other cc with the plugin
## note: MUST use the same compiler as the plugin use
# back to root of this repo
cd ../
$CXX -fplugin=./cmake-build-debug/TestLLVM01Lib.dylib ./test/test_main.cpp -v
./a.outllvm 15 is installed via sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)"
clang-15 -fplugin=./build/TestLLVM01Lib.so ./test/test_main.cpp -lstdc++on macOS
# -fsyntax-only 不会编译，只是生成结果
# -Xclang -plugin -Xclang optional-guard 相当于要传给 clang frontend 这样的参数 -plugin optional-guard
$CXX -fsyntax-only -std=c++17 -fplugin=./build/OptionalGuard/OptionalGuardPlugin.dylib -Xclang -plugin -Xclang optional-guard ./test/option_test_main.cpp -o ./option_test_main -v
去掉 -fsyntax-only 之后，会报 链接错误，原因是前一步编译结果没出来
compile test file function_pass_test.cpp to LLVM .ll file or bitcode file note: must use -O1 or upper
# use -S to emit a llvm .ll file
clang -std=c++14 -O1 -emit-llvm ./test/function_pass_test.cpp -S -o function_pass_test.ll
# use -c to emit a bitcode .bc file
clang -std=c++14 -O1 -emit-llvm ./test/function_pass_test.cpp -c -o function_pass_test.bc
compile our pass as InstructionCountPass.dylib
cd build
cmake --build .run opt with custom pass
# using function_pass_test.cc works well too
/opt/homebrew/opt/llvm@14/bin/opt --load-pass-plugin=/Users/joey/Documents/Code/TestLLVM01/build/InstructionCountPass/InstructionCountPass.dylib --passes="function(instruction-count)" -S -o - function_pass_test.llcompile our pass as AOPInjectionPass.dylib
cd build
cmake --build .
# cd back to root folder
# generate llvm IR
clang -std=c++14 -emit-llvm ./test/function_pass_test.cpp -S -o function_pass_test.ll
# run opt with custom pass AOPInjectionPass
# input file: function_pass_test.ll
# output file processed by custom pass: function_pass_test_after_pass.ll
/opt/homebrew/opt/llvm@14/bin/opt --load-pass-plugin=/Users/joey/Documents/Code/TestLLVM01/build/AOPInjectionPass/AOPInjectionPass.dylib --passes="aop-injection" --disable-output -S function_pass_test.ll -o function_pass_test_after_pass.ll
# compile ll file to object file
llc -filetype=obj function_pass_test_after_pass.ll -o function_pass_test_after_pass.o
# generate executable file with clang
clang -lc++ function_pass_test_after_pass.o -o function_pass_test_after_pass
# final step, let's run it:
./function_pass_test_after_pass上面的 AOPInjectionPass 需要手动传入 --passes="aop-injection" 参数来启动该 pass，另外一种方式是默认加载，区别是需要通过 PB.registerPipelineStartEPCallback() 来注册 pass
还有好处是，可以直接通过 clang 动态链接 pass plugin 的动态库：
clang -lc++ -std=c++14 -O3 -Xclang -fpass-plugin="/Users/joey/Documents/Code/TestLLVM01/build/AutoLoadAOPInjectionPass/AutoLoadAOPInjectionPass.dylib" ./test/function_pass_test.cpp -o function_pass_test
# 然后直接执行即可：
./function_pass_test
1
2
my_aop_intercepter_Z5hellov
hello
my_aop_intercepter_Z6hello2v
hello2
my_aop_intercepter_Z6hello3v
hello3AutoLoadAOPInjectionPassV2 实现的基本的 AOP 功能，支持通过 attribute 注入函数调用
// AOPInjectionPointCut 表示该函数可以被其他函数注入进去
// joined_point_cut:file 表示函数中包含 file 的将会在函数执行开始的时候注入调用 joinedpoint_file_related 函数
// 还需要满足另外一个条件是需要带有 Injected annotate 的函数才会被注入
__attribute__((annotate("AOPInjectionPointCut")))
__attribute__((annotate("joined_point_cut:file")))
void joinedpoint_file_related(char *func_name){
std::cout << "joinedpoint_file_related in " << func_name << std::endl;
}
// 函数中包含 file，且有 Injected annotation，因为会被注入 joinedpoint_file_related
__attribute__((annotate("Injected"))) void file_read();
void file_read() { std::cout << "file_read, should be injected." << std::endl; }
// >= C++11
// [[clang::annotate("Injected")]] 是 C++11 之后的写法，也会被注入
[[clang::annotate("Injected")]] void file_close(){
std::cout << "file_close, should be injected." << std::endl;
}
// 没有 Injected 属性，即便函数名中包含 file，也不会被注入
void file_write(){
std::cout << "file_close, should be injected." << std::endl;
}
How to play?
cd build/; cmake --build .; cd -
clang -lc++ -std=c++11 -O3 -Xclang -fpass-plugin="/Users/joey/Documents/Code/TestLLVM01/build/AutoLoadAOPInjectionPassV2/AutoLoadAOPInjectionPassV2.dylib" ./test/input_auto_aop_pass_v2.cpp -o input_auto_aop_pass_v2
./input_auto_aop_pass_v2
joinedpoint_file_related in _Z9file_readv
file_read, should be injected.
joinedpoint_file_related in _Z10file_closev
file_close, should be injected.
file_write, should NOT be injected.
joinedpoint_statistics in _Z18statistics_networkv
statistics_network, should be injected.
other func, should NOT be injected.on macOS
## enter clang-query interaction env
# genereate compile_commands.json file
cd some_build_folder
cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=1 .
# -p sepecify the compile_commands.json file generated in preceding step
/opt/homebrew/opt/llvm@14/bin/clang-query test/option_test_main.cpp -p build/compile_commands.json
## set traversal mode & output the generated AST tree of matched nodes
clang-query> set traversal IgnoreUnlessSpelledInSource
clang-query> set output dump
# clang-query> set bind-root false
clang-query> match functionDecl(hasName("bad_case")).bind("bad_case_function")
Match #1:
Binding for "bad_case_function":
FunctionDecl 0x1280debd8 </Users/joey/Documents/Code/TestLLVM01/test/option_test_main.cpp:20:1, line:24:1> line:20:6 used bad_case 'void ()'
`-CompoundStmt 0x1280dee70 <col:17, line:24:1>
`-DeclStmt 0x1280dee58 <line:22:3, col:26>
`-VarDecl 0x1280dece8 <col:3, col:25> col:7 value 'int' cinit
`-CallExpr 0x1280dee38 <col:15, col:25> '<dependent type>' contains-errors
`-CXXDependentScopeMemberExpr 0x1280dedf0 <col:15, col:19> '<dependent type>' contains-errors lvalue .value
`-RecoveryExpr 0x1280dedd0 <col:15> '<dependent type>' contains-errors lvalue
Binding for "root":
FunctionDecl 0x1280debd8 </Users/joey/Documents/Code/TestLLVM01/test/option_test_main.cpp:20:1, line:24:1> line:20:6 used bad_case 'void ()'
`-CompoundStmt 0x1280dee70 <col:17, line:24:1>
`-DeclStmt 0x1280dee58 <line:22:3, col:26>
`-VarDecl 0x1280dece8 <col:3, col:25> col:7 value 'int' cinit
`-CallExpr 0x1280dee38 <col:15, col:25> '<dependent type>' contains-errors
`-CXXDependentScopeMemberExpr 0x1280dedf0 <col:15, col:19> '<dependent type>' contains-errors lvalue .value
`-RecoveryExpr 0x1280dedd0 <col:15> '<dependent type>' contains-errors lvalue
See: Exploring Clang Tooling Part 2: Examining the Clang AST with clang-query
Code from test/input_shared_from_this_in_cons.cpp
class A : public std::enable_shared_from_this<A> {
public:
A() {
std::cout << "message from A::A()" << std::endl;
std::shared_ptr<A> p = shared_from_this(); // ❌ 🙅 crash here..
p->print();
}
void print() {
std::cout << "message from A::print()" << std::endl;
}
};
clang-query statement
// single line:
match cxxConstructorDecl(hasDescendant(cxxMemberCallExpr(on(cxxThisExpr()), callee(functionDecl(hasName("shared_from_this")))).bind("bad_call_shared_from_this"))).bind("bad_constructor")
// formated:
match cxxConstructorDecl(hasDescendant(
cxxMemberCallExpr(
on(cxxThisExpr()),
callee(functionDecl(hasName("shared_from_this")))
).bind("bad_call_shared_from_this")
)).bind("bad_constructor")run with
/opt/homebrew/opt/llvm@14/bin/clang-query test/input_shared_from_this_in_cons.cpp -p build/compile_commands.json