1 files changed, 102 insertions, 0 deletions
diff --git a/lib/CodeGen/CodeGen.cc b/lib/CodeGen/CodeGen.cc
new file mode 100644
index 0000000..a2de939
--- /dev/null
+++ b/lib/CodeGen/CodeGen.cc
@@ -0,0 +1,102 @@
+#include "cps/CodeGen.h"
+#include "llvm/IR/Verifier.h"
+
+using namespace llvm;
+using namespace cps;
+
+CodeGen::CodeGen() {
+    TheContext = std::make_unique<LLVMContext>();
+    TheModule = std::make_unique<Module>("cps_module", *TheContext);
+    Builder = std::make_unique<IRBuilder<>>(*TheContext);
+    
+    SetupExternalFunctions();
+}
+
+void CodeGen::SetupExternalFunctions() {
+    // printf(i8*, ...)
+    std::vector<Type*> PrintfArgs;
+    PrintfArgs.push_back(PointerType::getUnqual(*TheContext));
+    FunctionType *PrintfType = FunctionType::get(Type::getInt32Ty(*TheContext), PrintfArgs, true);
+    PrintfFunc = TheModule->getOrInsertFunction("printf", PrintfType);
+
+    // scanf(i8*, ...)
+    FunctionType *ScanfType = FunctionType::get(Type::getInt32Ty(*TheContext), PrintfArgs, true);
+    ScanfFunc = TheModule->getOrInsertFunction("scanf", ScanfType);
+
+    // format %d\n and %d
+    PrintfFormatStr = Builder->CreateGlobalStringPtr("%d\n", "fmt_nl", 0, TheModule.get());
+    ScanfFormatStr = Builder->CreateGlobalStringPtr("%d", "fmt_in", 0, TheModule.get());
+}
+
+AllocaInst *CodeGen::CreateEntryBlockAlloca(Function *TheFunction, const std::string &VarName) {
+    IRBuilder<> TmpB(&TheFunction->getEntryBlock(), TheFunction->getEntryBlock().begin());
+    return TmpB.CreateAlloca(Type::getInt32Ty(*TheContext), nullptr, VarName);
+}
+
+void CodeGen::compile(const std::vector<std::unique_ptr<StmtAST>> &Statements) {
+    FunctionType *FT = FunctionType::get(Type::getInt32Ty(*TheContext), false);
+    Function *F = Function::Create(FT, Function::ExternalLinkage, "main", TheModule.get());
+    BasicBlock *BB = BasicBlock::Create(*TheContext, "entry", F);
+    Builder->SetInsertPoint(BB);
+
+    for (const auto &Stmt : Statements) {
+        // DECLARE 
+        if (auto *Decl = dynamic_cast<DeclareStmtAST*>(Stmt.get())) {
+            AllocaInst *Alloca = CreateEntryBlockAlloca(F, Decl->getName());
+            NamedValues[Decl->getName()] = Alloca;
+            // 0
+            Builder->CreateStore(ConstantInt::get(*TheContext, APInt(32, 0)), Alloca);
+        }
+        // ASSIGNMENT (x <- expr) 
+        else if (auto *Assign = dynamic_cast<AssignStmtAST*>(Stmt.get())) {
+            Value *Val = nullptr;
+            if (auto *Num = dynamic_cast<NumberExprAST*>(Assign->getExpr())) {
+                Val = ConstantInt::get(*TheContext, APInt(32, Num->getVal()));
+            } else if (auto *Var = dynamic_cast<VariableExprAST*>(Assign->getExpr())) {
+                 AllocaInst *A = NamedValues[Var->getName()];
+                 Val = Builder->CreateLoad(Type::getInt32Ty(*TheContext), A, Var->getName());
+            }
+
+            AllocaInst *Alloca = NamedValues[Assign->getName()];
+            if (Alloca && Val) {
+                Builder->CreateStore(Val, Alloca);
+            }
+        }
+        // INPUT 
+        else if (auto *In = dynamic_cast<InputStmtAST*>(Stmt.get())) {
+            AllocaInst *Alloca = NamedValues[In->getName()];
+            if (Alloca) {
+                std::vector<Value*> Args;
+                Args.push_back(ScanfFormatStr);
+                Args.push_back(Alloca);
+                Builder->CreateCall(ScanfFunc, Args);
+            }
+        }
+        // OUTPUT
+        else if (auto *Out = dynamic_cast<OutputStmtAST*>(Stmt.get())) {
+            Value *Val = nullptr;
+            if (auto *Num = dynamic_cast<NumberExprAST*>(Out->getExpr())) {
+                Val = ConstantInt::get(*TheContext, APInt(32, Num->getVal()));
+            } else if (auto *Var = dynamic_cast<VariableExprAST*>(Out->getExpr())) {
+                 AllocaInst *A = NamedValues[Var->getName()];
+                 Val = Builder->CreateLoad(Type::getInt32Ty(*TheContext), A, Var->getName());
+            }
+
+            if (Val) {
+                // printf("%d\n", val)
+                std::vector<Value*> Args;
+                Args.push_back(PrintfFormatStr);
+                Args.push_back(Val);
+                Builder->CreateCall(PrintfFunc, Args);
+            }
+        }
+    }
+
+    // main return 0
+    Builder->CreateRet(ConstantInt::get(*TheContext, APInt(32, 0)));
+    verifyFunction(*F);
+}
+
+void CodeGen::print() {
+    TheModule->print(errs(), nullptr);
+}