llvm提取c/c++ ast树

一、llvm提取程序ast树

1.1、源代码

//main.c
#include <iostream>
#include "StaticMath.h"
#include "DynamicMath.h"
int main()
{
    double a=1.2;
    double b=2.4;
    std::cout << "static  : a+b="<<StaticMath::add(a,b)<<std::endl;
    std::cout << "dynamic : a+b =" << DynamicMath::add(a,b)<<std::endl;
    return 0;
}

1.2、获取AST中main的代码

Clang -fsyntax-only -Xclang -ast-dump test.cpp
-fsyntax-only意味着只解析语法，不进行编译和链接；-Xclang 是要使用clang特定的Xclang功能-ast-dump是要打印AST
或者
clang-check -p main.c -ast-dump -ast-dump-filter main

1.3、AST树的结果

FunctionDecl 0x55eed4d4d728 </media/data/clang-llvm/TestC/main.c:8:1, line:19:1> line:8:5 main 'int ()'
`-CompoundStmt 0x55eed4d4e158 <col:11, line:19:1>
  |-DeclStmt 0x55eed4d4d840 <line:9:5, col:13>
  | `-VarDecl 0x55eed4d4d7d8 <col:5, col:12> col:12 used a 'PARAMS':'struct params'
  |-DeclStmt 0x55eed4d4d8d0 <line:10:5, col:13>
  | `-VarDecl 0x55eed4d4d868 <col:5, col:12> col:12 used b 'PARAMS':'struct params'
  |-DeclStmt 0x55eed4d4da90 <line:11:5, col:28>
  | `-VarDecl 0x55eed4d4d8f8 <col:5, col:27> col:12 used c 'RETURN':'struct returns' cinit
  |   `-CallExpr 0x55eed4d4da30 <col:15, col:27> 'RETURN':'struct returns'
  |     |-ImplicitCastExpr 0x55eed4d4da18 <col:15> 'RETURN (*)(PARAMS, PARAMS)' <FunctionToPointerDecay>
  |     | `-DeclRefExpr 0x55eed4d4d960 <col:15> 'RETURN (PARAMS, PARAMS)' Function 0x55eed4d4d268 'Function' 'RETURN (PARAMS, PARAMS)'
  |     |-ImplicitCastExpr 0x55eed4d4da60 <col:24> 'PARAMS':'struct params' <LValueToRValue>
  |     | `-DeclRefExpr 0x55eed4d4d980 <col:24> 'PARAMS':'struct params' lvalue Var 0x55eed4d4d7d8 'a' 'PARAMS':'struct params'
  |     `-ImplicitCastExpr 0x55eed4d4da78 <col:26> 'PARAMS':'struct params' <LValueToRValue>
  |       `-DeclRefExpr 0x55eed4d4d9a0 <col:26> 'PARAMS':'struct params' lvalue Var 0x55eed4d4d868 'b' 'PARAMS':'struct params'
  |-DeclStmt 0x55eed4d4dc50 <line:12:5, col:29>
  | `-VarDecl 0x55eed4d4dab8 <col:5, col:28> col:11 used d 'EMPTY':'EMPTY' cinit
  |   `-CallExpr 0x55eed4d4dbf0 <col:15, col:28> 'EMPTY':'EMPTY'
  |     |-ImplicitCastExpr 0x55eed4d4dbd8 <col:15> 'EMPTY (*)(PARAMS, PARAMS)' <FunctionToPointerDecay>
  |     | `-DeclRefExpr 0x55eed4d4db20 <col:15> 'EMPTY (PARAMS, PARAMS)' Function 0x55eed4d4d4d8 'Function2' 'EMPTY (PARAMS, PARAMS)'
  |     |-ImplicitCastExpr 0x55eed4d4dc20 <col:25> 'PARAMS':'struct params' <LValueToRValue>
  |     | `-DeclRefExpr 0x55eed4d4db40 <col:25> 'PARAMS':'struct params' lvalue Var 0x55eed4d4d7d8 'a' 'PARAMS':'struct params'
  |     `-ImplicitCastExpr 0x55eed4d4dc38 <col:27> 'PARAMS':'struct params' <LValueToRValue>
  |       `-DeclRefExpr 0x55eed4d4db60 <col:27> 'PARAMS':'struct params' lvalue Var 0x55eed4d4d868 'b' 'PARAMS':'struct params'
  |-BinaryOperator 0x55eed4d4dd30 <line:13:5, col:17> 'int' '='
  | |-DeclRefExpr 0x55eed4d4dc68 <col:5> 'int' lvalue Var 0x55eed4d4d698 'e' 'int'
  | `-CallExpr 0x55eed4d4dcf0 <col:7, col:17> 'int'
  |   `-ImplicitCastExpr 0x55eed4d4dcd8 <col:7> 'int (*)()' <FunctionToPointerDecay>
  |     `-DeclRefExpr 0x55eed4d4dc88 <col:7> 'int ()' Function 0x55eed4d4d5e0 'Function3' 'int ()'
  |-CallExpr 0x55eed4d4de70 <line:15:5, col:27> 'int'
  | |-ImplicitCastExpr 0x55eed4d4de58 <col:5> 'int (*)(const char *, ...)' <FunctionToPointerDecay>
  | | `-DeclRefExpr 0x55eed4d4dd50 <col:5> 'int (const char *, ...)' Function 0x55eed4d26d70 'printf' 'int (const char *, ...)'
  | |-ImplicitCastExpr 0x55eed4d4deb8 <col:12> 'const char *' <NoOp>
  | | `-ImplicitCastExpr 0x55eed4d4dea0 <col:12> 'char *' <ArrayToPointerDecay>
  | |   `-StringLiteral 0x55eed4d4dda8 <col:12> 'char [3]' lvalue "%d"
  | `-ImplicitCastExpr 0x55eed4d4ded0 <col:17, col:19> 'int' <LValueToRValue>
  |   `-MemberExpr 0x55eed4d4dde8 <col:17, col:19> 'int' lvalue .returns2 0x55eed4d4cf90
  |     `-DeclRefExpr 0x55eed4d4ddc8 <col:17> 'RETURN':'struct returns' lvalue Var 0x55eed4d4d8f8 'c' 'RETURN':'struct returns'
  |-CallExpr 0x55eed4d4dfa8 <line:16:5, col:25> 'int'
  | |-ImplicitCastExpr 0x55eed4d4df90 <col:5> 'int (*)(const char *, ...)' <FunctionToPointerDecay>
  | | `-DeclRefExpr 0x55eed4d4dee8 <col:5> 'int (const char *, ...)' Function 0x55eed4d26d70 'printf' 'int (const char *, ...)'
  | |-ImplicitCastExpr 0x55eed4d4dff0 <col:12> 'const char *' <NoOp>
  | | `-ImplicitCastExpr 0x55eed4d4dfd8 <col:12> 'char *' <ArrayToPointerDecay>
  | |   `-StringLiteral 0x55eed4d4df08 <col:12> 'char [3]' lvalue "%d"
  | `-ImplicitCastExpr 0x55eed4d4e008 <col:17, col:19> 'int' <LValueToRValue>
  |   `-MemberExpr 0x55eed4d4df48 <col:17, col:19> 'int' lvalue .empty1 0x55eed4d482a8
  |     `-DeclRefExpr 0x55eed4d4df28 <col:17> 'EMPTY':'EMPTY' lvalue Var 0x55eed4d4dab8 'd' 'EMPTY':'EMPTY'
  |-CallExpr 0x55eed4d4e0b0 <line:17:5, col:18> 'int'
  | |-ImplicitCastExpr 0x55eed4d4e098 <col:5> 'int (*)(const char *, ...)' <FunctionToPointerDecay>
  | | `-DeclRefExpr 0x55eed4d4e020 <col:5> 'int (const char *, ...)' Function 0x55eed4d26d70 'printf' 'int (const char *, ...)'
  | |-ImplicitCastExpr 0x55eed4d4e0f8 <col:12> 'const char *' <NoOp>
  | | `-ImplicitCastExpr 0x55eed4d4e0e0 <col:12> 'char *' <ArrayToPointerDecay>
  | |   `-StringLiteral 0x55eed4d4e040 <col:12> 'char [3]' lvalue "%d"
  | `-ImplicitCastExpr 0x55eed4d4e110 <col:17> 'int' <LValueToRValue>
  |   `-DeclRefExpr 0x55eed4d4e060 <col:17> 'int' lvalue Var 0x55eed4d4d698 'e' 'int'
  `-ReturnStmt 0x55eed4d4e148 <line:18:5, col:12>
    `-IntegerLiteral 0x55eed4d4e128 <col:12> 'int' 0

二、AST树节点介绍

2.1、TranslationUnitDecl

顶层结构是TranslationUnitDecl，对AST树的遍历

2.2、FunctionDecl

函数符号

2.3、ParmVarDecl

参数符号

2.4、VarDecl

变量定义，如果有初始化，可以通过getInit()获取到对应的初始化Expr

2.5、RecordDecl

union和struct的符号的声明，采用的是RecordDecl的形式。

2.6、FieldDecl

struct内部的符号的定义

2.7、CompoundStmt

代表大括号，函数实现、struct、enum、for的body等一般用此包起来。

2.8、DeclStmt

定义语句，里边可能有VarDecl等类型的定义

2.9、BinaryOperator

赋值语句，例如int a = b;

2.10、CallExpr

函数调用Expr，子节点有调用的参数列表

2.11、ReturnStmt

返回语句

2.12、DeclRefExpr

引用的语句，是引用我们之前声明的一些符号的语句