安装LLVM

Clone llvm
git clone https://github.com/llvm/llvm-project.git

Build
cd llvm-project cmake -S llvm -B build -G Ninja -DLLVM_ENABLE_PROJECTS=clang -DCMAKE_BUILD_TYPE=Release cmake --build build

Test
cmake --build build --target check-all

Install
cmake --install build

LLVM tutorial

1.词法解析：万花筒: 万花筒介绍和词法分析器

#include<iostream>

enum Token {
    tok_eof = -1,

    // commands 
    tok_def = -2,
    tok_extern = -3,

    // primary
    tok_identifier = -4,
    tok_number = -5
};

static std::string IdentifierStr;
static double NumVal;

static int gettok(){
    static int LastChar = ' ';
    
    // skip white
    while(isspace(LastChar)) LastChar = getchar();

    // keyword & identifier
    if(isalpha(LastChar)) {
        IdentifierStr = LastChar;
        while(isalnum(LastChar = getchar())) IdentifierStr += LastChar;

        // keyword
        if(IdentifierStr == "def") return tok_def;
        if(IdentifierStr == "extern") return tok_extern;

        // identifier
        return tok_identifier;
    }

    // number
    if(isdigit(LastChar) || LastChar == '.') {
        std::string NumStr;
        do{
            NumStr += LastChar;
            LastChar = getchar();
        } while(isdigit(LastChar) || LastChar == '.');

        NumVal = strtod(NumStr.c_str(),0);
        return tok_number;
    }

    // comment
    if(LastChar == '#') {
        do LastChar = getchar();
        while(LastChar != EOF && LastChar != '\n' && LastChar != '\r');

        if(LastChar != EOF) return gettok();
    }

    // end
    if(LastChar == EOF) return tok_eof;

    // other character
    int ThisChar = LastChar;
    LastChar = getchar();
    return ThisChar;
}

int main()
{
    int Tok;
    do {
        Tok = gettok();
        std::cout<<Tok<<std::endl;
    } while(Tok != tok_eof);
    
    return 0;
}

参考

• C++&LLVM入门项目/教程：手把手带你完成LLVM Tutorial 1.词法分析器
• 我的第一个使用 LLVM 的语言前端教程
• Kaleidoscope