1 files changed, 125 insertions, 0 deletions
diff --git a/lib/CodeGen/FunctionGen.cc b/lib/CodeGen/FunctionGen.cc
new file mode 100644
index 0000000..b2adc08
--- /dev/null
+++ b/lib/CodeGen/FunctionGen.cc
@@ -0,0 +1,125 @@
+#include "cps/FunctionGen.h"
+#include "llvm/IR/Verifier.h"
+#include <iostream>
+
+using namespace llvm;
+using namespace cps;
+
+Type *FunctionGen::getLLVMType(const std::string &TypeName) {
+    if (TypeName == "INTEGER") return Type::getInt64Ty(Context);
+    if (TypeName == "BOOLEAN") return Type::getInt1Ty(Context);
+    if (TypeName == "REAL")    return Type::getDoubleTy(Context);
+    if (TypeName == "VOID")    return Type::getVoidTy(Context);
+    return Type::getInt64Ty(Context);
+}
+
+void FunctionGen::createArgumentAllocas(Function *F, const std::vector<std::pair<std::string, std::string>> &Args) {
+    Function::arg_iterator AI = F->arg_begin();
+    for (unsigned Idx = 0, E = Args.size(); Idx != E; ++Idx, ++AI) {
+        std::string ArgName = Args[Idx].first;
+        std::string ArgTypeStr = Args[Idx].second;
+        
+        Type *ArgType = getLLVMType(ArgTypeStr);
+        IRBuilder<> TmpB(&F->getEntryBlock(), F->getEntryBlock().begin());
+        AllocaInst *Alloca = TmpB.CreateAlloca(ArgType, nullptr, ArgName);
+        
+        Value *ArgVal = &(*AI);
+        Builder.CreateStore(ArgVal, Alloca);
+        
+        NamedValues[ArgName] = Alloca; 
+    }
+}
+
+Function *FunctionGen::emitPrototype(PrototypeAST *Proto) {
+    std::vector<Type*> ArgTypes;
+    for (const auto &Arg : Proto->getArgs()) {
+        ArgTypes.push_back(getLLVMType(Arg.second));
+    }
+
+    Type *RetType = getLLVMType(Proto->getReturnType());
+    FunctionType *FT = FunctionType::get(RetType, ArgTypes, false);
+    Function *F = Function::Create(FT, Function::ExternalLinkage, Proto->getName(), &Module);
+
+    unsigned Idx = 0;
+    for (auto &Arg : F->args()) {
+        if (Idx < Proto->getArgs().size())
+            Arg.setName(Proto->getArgs()[Idx++].first);
+    }
+    return F;
+}
+
+Function *FunctionGen::emitFunctionDef(FunctionDefAST *FuncAST, 
+                                       const std::function<void(StmtAST*)> &StmtEmitter) {
+    PrototypeAST *Proto = FuncAST->getProto();
+    Function *TheFunction = Module.getFunction(Proto->getName());
+
+    if (!TheFunction)
+        TheFunction = emitPrototype(Proto);
+
+    if (!TheFunction) return nullptr;
+    if (!TheFunction->empty()) {
+        fprintf(stderr, "Error: Function %s cannot be redefined.\n", Proto->getName().c_str());
+        return nullptr;
+    }
+
+    BasicBlock *BB = BasicBlock::Create(Context, "entry", TheFunction);
+    Builder.SetInsertPoint(BB);
+
+    std::map<std::string, llvm::AllocaInst*> OldNamedValues = NamedValues;
+    NamedValues.clear();
+    
+    createArgumentAllocas(TheFunction, Proto->getArgs());
+
+    for (const auto &Stmt : FuncAST->getBody()) {
+        StmtEmitter(Stmt.get());
+    }
+
+    if (!Builder.GetInsertBlock()->getTerminator()) {
+        if (Proto->getReturnType() == "VOID")
+            Builder.CreateRetVoid();
+        else
+            Builder.CreateRet(Constant::getNullValue(TheFunction->getReturnType()));
+    }
+
+    verifyFunction(*TheFunction);
+    NamedValues = OldNamedValues;
+    return TheFunction;
+}
+
+static Value *GenerateCall(llvm::Module &Module, llvm::IRBuilder<> &Builder, llvm::LLVMContext &Context,
+                    const std::string &CalleeName, const std::vector<llvm::Value*> &Args) {
+    Function *CalleeF = Module.getFunction(CalleeName);
+    if (!CalleeF) {
+        std::vector<Type*> ArgTypes;
+        for (auto *Val : Args) ArgTypes.push_back(Val->getType());
+        FunctionType *FT = FunctionType::get(Type::getInt64Ty(Context), ArgTypes, false);
+        CalleeF = Function::Create(FT, Function::ExternalLinkage, CalleeName, &Module);
+    }
+
+    if (CalleeF->arg_size() != Args.size()) {
+        fprintf(stderr, "Error: Incorrect # arguments passed to %s\n", CalleeName.c_str());
+        return nullptr;
+    }
+
+    if (CalleeF->getReturnType()->isVoidTy()) {
+        return Builder.CreateCall(CalleeF, Args);
+    }
+
+    return Builder.CreateCall(CalleeF, Args, "calltmp");
+}
+
+llvm::Value *FunctionGen::emitCallExpr(CallExprAST *Call, const std::vector<llvm::Value*> &Args) {
+    return GenerateCall(Module, Builder, Context, Call->getCallee(), Args);
+}
+
+void FunctionGen::emitCallStmt(CallStmtAST *Call, const std::vector<llvm::Value*> &Args) {
+    GenerateCall(Module, Builder, Context, Call->getCallee(), Args);
+}
+
+void FunctionGen::emitReturn(ReturnStmtAST *Ret, llvm::Value *RetVal) {
+    if (RetVal) {
+        Builder.CreateRet(RetVal);
+    } else {
+        Builder.CreateRetVoid();
+    }
+}