本篇文章为大家展示了LLVM IR字符串类型拼接方法是怎样的,内容简明扼要并且容易理解,绝对能使你眼前一亮,通过这篇文章的详细介绍希望你能有所收获。
IR语义为将字符串与整型进行拼接操作;方法虽然笨拙,但能够满足目前的业务需求,今分享出来供大家交流与参考。代码运行环境为LLVM6.0。 关键字:LLVM、字符串、char*、string、拼接 、concat、IR
#include "llvm/IR/IRBuilder.h" #include "llvm/IR/Verifier.h" #include "llvm/Support/TargetSelect.h" #include "llvm/ExecutionEngine/ExecutionEngine.h" #include "llvm/IR/LLVMContext.h" #include "llvm/IR/Module.h" #include "llvm/IR/Function.h" #include "llvm/IR/BasicBlock.h" #include "llvm/ExecutionEngine/MCJIT.h" #include "llvm/IR/TypeBuilder.h" #include <iostream> #include <algorithm> #include <cassert> #include <cctype> #include <cstdint> #include <cstdio> #include <cstdlib> #include <map> #include <memory> #include <string> #include <vector> using namespace llvm; using namespace std; //字符串拼接操作放在C++端进行 char* javaMethodAdd( int x, char * str) { cout << "arg x:"<< x << endl; string str1 = str; string xstr = to_string(x); str1+= xstr; char *st1 = const_cast<char *>(str1.c_str()) ; return st1; } int main() { llvm::LLVMContext *context = new llvm::LLVMContext(); llvm::Module *module = new llvm::Module("test", *context); std::vector<llvm::Type *> arg_types = { llvm::Type::getInt32Ty(*context), llvm::Type::getInt32Ty(*context)}; //函数参数,返回类型为char指针 llvm::FunctionType *ftype = llvm::FunctionType::get( llvm::Type::getInt8PtrTy(*context), arg_types,false); llvm::Function *func = llvm::Function::Create( ftype, llvm::GlobalValue::LinkageTypes::ExternalLinkage, "my_func", module); func->setCallingConv(llvm::CallingConv::C); llvm::BasicBlock *bb = llvm::BasicBlock::(*context, "entry", func); llvm::IRBuilder<> builder(*context); builder.SetInsertPoint(bb); //获取传入的参数 llvm::Argument *arg0 = func->arg_begin() + 0; llvm::Argument *arg1 = func->arg_begin() + 1; //string begain------------------ //LLVM字符串常量 Constant *const_array_str = ConstantDataArray::getString(*context, "beeeeegineeee", false); //申请内存空间 AllocaInst* const_array_addr = builder.CreateAlloca(const_array_str->getType(), ConstantExpr::getSizeOf(const_array_str->getType()),"temaddr"); const_array_addr->setAlignment (1); std::vector<Value*> index_vector; index_vector.push_back(ConstantInt::get(Type::getInt32Ty(*context), 0)); auto valueAsPtr = builder.CreateGEP(const_array_addr, index_vector, "tmp"); // 存储字符串到内存空间 StoreInst *sist = builder.CreateStore(const_array_str, valueAsPtr); sist->setAlignment (1); index_vector.push_back(ConstantInt::get(Type::getInt64Ty(*context), 0)); //创建指向字符串存储内存空间的指针 auto retRes = builder.CreateInBoundsGEP( const_array_str->getType(), const_array_addr, index_vector, "tmpstr"); //string end--------------------------- //llvm::Value *result = builder.CreateAdd(arg0, arg1, "result"); llvm::Value* result = builder.CreateBinOp(llvm::Instruction::Add, arg0, arg1, "result"); //忽略函数名称(可改为任意的) FunctionType* double_add_double_type = TypeBuilder<char*(int,char*), false>::get(*context); Function* fdouble_add_double = cast<Function>(module->getOrInsertFunction("double_add_double", double_add_double_type)); std::vector<llvm::Value*> args; args.push_back(result); args.push_back(retRes); Value* ret = builder.CreateCall(fdouble_add_double, args); builder.CreateRet(ret); llvm::InitializeNativeTarget(); llvm::InitializeNativeTargetAsmPrinter(); llvm::InitializeNativeTargetAsmParser(); //创建执行引擎 llvm::ExecutionEngine *ee = llvm::EngineBuilder(std::unique_ptr<llvm::Module>(module)).setEngineKind(llvm::EngineKind::JIT).create(); printf("executed .........segment........\n"); //LLVM函数与C++函数映射 ee->addGlobalMapping(fdouble_add_double, (char*)javaMethodAdd); ee->finalizeObject(); char* (*add)(int, int) = (char* (*)(int, int))ee->getFunctionAddress("my_func"); printf("Result: %s\n", add(43, 10)); return 0; }
//编译和运行命令(Linux)。
// clang++ -O3 cppName.cpp -o test.bc `llvm-config --cflags --ldflags
llvm-config --libs
llvm-config --system-libs `
// ./test.bc
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