chapter02-7.cpp

#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include <vector>

using namespace llvm;

LLVMContext Context;
static Module *ModuleOb = new Module("my compiler", Context);
static std::vector<std::string> FunArgs;

Function *createFunc(IRBuilder<> &Builder, std::string Name) {
  std::vector<Type *> Integers(FunArgs.size(), Type::getInt32Ty(Context));
  FunctionType *funcType =
    llvm::FunctionType::get(Builder.getInt32Ty(),Integers, false);
  Function *fooFunc = llvm::Function::Create(
					     funcType, llvm::Function::ExternalLinkage, Name, ModuleOb);
  return fooFunc;
}

void setFuncArgs(Function *fooFunc, std::vector<std::string> FunArgs) {
  unsigned Idx = 0;
  Function::arg_iterator AI, AE;
  for(AI = fooFunc->arg_begin(), AE = fooFunc->arg_end(); AI != AE;
      ++AI, ++Idx)
    AI->setName(FunArgs[Idx]);
}

BasicBlock *createBB(Function *fooFunc, std::string Name) {
  return BasicBlock::Create(Context, Name, fooFunc);
}

GlobalVariable *createGlob(IRBuilder<> &Builder, std::string Name) {
  ModuleOb->getOrInsertGlobal(Name, Builder.getInt32Ty());
  GlobalVariable *gVar = ModuleOb->getNamedGlobal(Name);
  gVar->setLinkage(GlobalValue::CommonLinkage);
  gVar->setAlignment(4);
  return gVar;
}

Value *createArith(IRBuilder<> &Builder, Value *L, Value *R) {
  return Builder.CreateMul(L, R, "multmp");
}

int main(int argc, char *argv[])
{
  FunArgs.push_back("a");
  FunArgs.push_back("b");

  static IRBuilder<> Builder(Context);
  GlobalVariable *gVar = createGlob(Builder, "x");
  Function *fooFunc = createFunc(Builder, "foo");
  setFuncArgs(fooFunc, FunArgs);
  BasicBlock *entry = createBB(fooFunc, "entry");
  Builder.SetInsertPoint(entry);
  Value *Arg1 = fooFunc->arg_begin();
  Value *constant = Builder.getInt32(16);
  Value *val = createArith(Builder, Arg1, constant);
  Builder.CreateRet(val);
  verifyFunction(*fooFunc);
  ModuleOb->print(llvm::outs(), nullptr);
  return 0;
}