pw_6/Student/task2/cpp/while_gen.cpp

#include "BasicBlock.h"
#include "Constant.h"
#include "Function.h"
#include "IRStmtBuilder.h"
#include "Module.h"
#include "Type.h"

#include <iostream>
#include <memory>

#ifdef DEBUG  // 用于调试信息,大家可以在编译过程中通过" -DDEBUG"来开启这一选项
#define DEBUG_OUTPUT std::cout << __LINE__ << std::endl;  // 输出行号的简单示例
#else
#define DEBUG_OUTPUT
#endif

#define CONST_INT(num) \
    ConstantInt::create(num, module)

#define CONST_FP(num) \
    ConstantFloat::create(num, module) // 得到常数值的表示,方便后面多次用到

using namespace SysYF::IR;

int main() {
    auto module = Module::create("SysYF code");  // module name是什么无关紧要
    auto builder = IRStmtBuilder::create(nullptr, module);
    SysYF::Ptr<Type> Int32Type = Type::get_int32_type(module);

    // int a;
    auto a = GlobalVariable::create("a", module, Int32Type, false, CONST_INT(0));

    // int b;
    auto b = GlobalVariable::create("b", module, Int32Type, false, CONST_INT(0));

    // main函数
    auto mainFun = Function::create(FunctionType::create(Int32Type, {}),
                                    "main", module);
    auto bb = BasicBlock::create(module, "entry", mainFun);
    // BasicBlock的名字在生成中无所谓,但是可以方便阅读
    builder->set_insert_point(bb);

    auto retAlloca = builder->create_alloca(Int32Type);
    
    // b=0;
    builder->create_store(CONST_INT(0), b);
    
    // a = 3;
    builder->create_store(CONST_INT(3), a);

    // whileBBs
    auto condBB = BasicBlock::create(module, "condBB_while", mainFun);
    auto trueBB = BasicBlock::create(module, "trueBB_while", mainFun);
    auto falseBB = BasicBlock::create(module, "falseBB_while", mainFun);

    builder->create_br(condBB);

    // condBB
    builder->set_insert_point(condBB);
    auto aLoad = builder->create_load(a);
    auto icmp = builder->create_icmp_gt(aLoad, CONST_INT(0));
    builder->create_cond_br(icmp, trueBB, falseBB);

    // trueBB
    builder->set_insert_point(trueBB);
    aLoad = builder->create_load(a);
    auto bLoad = builder->create_load(b);
    auto add = builder->create_iadd(bLoad, aLoad);
    builder->create_store(add, b);
    auto sub = builder->create_isub(aLoad, CONST_INT(1));
    builder->create_store(sub, a);
    builder->create_br(condBB);

    // falseBB
    builder->set_insert_point(falseBB);
    bLoad = builder->create_load(b);
    builder->create_store(bLoad, retAlloca);
    auto retLoad = builder->create_load(retAlloca);
    builder->create_ret(retLoad);

    std::cout << module->print();
    return 0;
}