Added runtime check for array index and division

3 files changed, 83 insertions, 8 deletions

diff --git a/lib/CodeGen/ArrayHandler.cc b/lib/CodeGen/ArrayHandler.cc
index 470cffa..499fd2d 100644
--- a/lib/CodeGen/ArrayHandler.cc
+++ b/lib/CodeGen/ArrayHandler.cc
@@ -8,8 +8,8 @@
 using namespace llvm;
 using namespace cps;
 
-ArrayHandler::ArrayHandler(LLVMContext &C, IRBuilder<> &B, Module &M, std::map<std::string, AllocaInst*> &NV)
-    : TheContext(&C), Builder(&B), TheModule(&M), NamedValues(&NV) {
+ArrayHandler::ArrayHandler(LLVMContext &C, IRBuilder<> &B, Module &M, std::map<std::string, AllocaInst*> &NV, RuntimeCheck &RC)
+    : TheContext(&C), Builder(&B), TheModule(&M), NamedValues(&NV), RuntimeChecker(RC) {
     setupExternalFunctions();
 }
 
@@ -115,8 +115,13 @@ Value* ArrayHandler::emitArrayAccess(ArrayAccessExprAST *Expr, CodeGen &CG) {
     }
 
     std::vector<Value*> Indices;
-    for (const auto &IdxExpr : Expr->getIndices()) {
-        Indices.push_back(CG.emitExpr(IdxExpr.get()));
+    for (size_t i = 0; i < Expr->getIndices().size(); ++i) {
+        Value *Idx = CG.emitExpr(Expr->getIndices()[i].get());
+        Indices.push_back(Idx);
+
+        Value *Lower = Meta.LowerBounds[i];
+        Value *Upper = Meta.UpperBounds[i];
+        RuntimeChecker.emitIndexCheck(Idx, Lower, Upper, Expr->getLine());
     }
     
     Value *Offset = computeFlatIndex(Name, Indices);
@@ -137,8 +142,14 @@ void ArrayHandler::emitArrayAssign(ArrayAssignStmtAST *Stmt, CodeGen &CG) {
     }
     
     std::vector<Value*> Indices;
-    for (const auto &IdxExpr : Stmt->getIndices()) {
-        Indices.push_back(CG.emitExpr(IdxExpr.get()));
+    for (size_t i = 0; i < Stmt->getIndices().size(); ++i) {
+        Value *Idx = CG.emitExpr(Stmt->getIndices()[i].get());
+        Indices.push_back(Idx);
+
+        const auto &Meta = ArrayTable[Name];
+        Value *Lower = Meta.LowerBounds[i];
+        Value *Upper = Meta.UpperBounds[i];
+        RuntimeChecker.emitIndexCheck(Idx, Lower, Upper, Stmt->getLine());
     }
     
     Value *Val = CG.emitExpr(Stmt->getExpr());
diff --git a/lib/CodeGen/CodeGen.cc b/lib/CodeGen/CodeGen.cc
index 57d76eb..e2c959e 100644
--- a/lib/CodeGen/CodeGen.cc
+++ b/lib/CodeGen/CodeGen.cc
@@ -13,7 +13,9 @@ CodeGen::CodeGen() {
     TheModule = std::make_unique<Module>("cps_module", *TheContext);
     Builder = std::make_unique<IRBuilder<>>(*TheContext);
     
-    Arrays = std::make_unique<ArrayHandler>(*TheContext, *Builder, *TheModule, NamedValues);
+    RuntimeChecker = std::make_unique<RuntimeCheck>(*TheModule, *TheContext, *Builder);
+    
+    Arrays = std::make_unique<ArrayHandler>(*TheContext, *Builder, *TheModule, NamedValues, *RuntimeChecker);
     
     SetupExternalFunctions();
 }
@@ -89,7 +91,9 @@ Value *CodeGen::emitExpr(ExprAST *Expr) {
         case '+': return Builder->CreateAdd(L, R, "addtmp");
         case '-': return Builder->CreateSub(L, R, "subtmp");
         case '*': return Builder->CreateMul(L, R, "multmp");
-        case '/': return Builder->CreateSDiv(L, R, "divtmp");
+        case '/': 
+            RuntimeChecker->emitDivZeroCheck(R, Bin->getLine());
+            return Builder->CreateSDiv(L, R, "divtmp");
         case tok_eq: return Builder->CreateICmpEQ(L, R, "eqtmp");
         case tok_ne: return Builder->CreateICmpNE(L, R, "netmp");
         case '<':    return Builder->CreateICmpSLT(L, R, "slttmp");
diff --git a/lib/CodeGen/RuntimeCheck.cc b/lib/CodeGen/RuntimeCheck.cc
new file mode 100644
index 0000000..cab50d5
--- /dev/null
+++ b/lib/CodeGen/RuntimeCheck.cc
@@ -0,0 +1,60 @@
+#include "cps/RuntimeCheck.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Type.h"
+#include "llvm/IR/Constants.h"
+
+using namespace llvm;
+using namespace cps;
+
+RuntimeCheck::RuntimeCheck(Module &M, LLVMContext &C, IRBuilder<> &B)
+    : TheModule(M), TheContext(C), Builder(B) {
+    setupExternalFunctions();
+}
+
+void RuntimeCheck::setupExternalFunctions() {
+    std::vector<Type*> PrintfArgs;
+    PrintfArgs.push_back(PointerType::getUnqual(TheContext));
+    FunctionType *PrintfType = FunctionType::get(Type::getInt32Ty(TheContext), PrintfArgs, true);
+    PrintfFunc = TheModule.getOrInsertFunction("printf", PrintfType);
+
+    std::vector<Type*> ExitArgs;
+    ExitArgs.push_back(Type::getInt32Ty(TheContext));
+    FunctionType *ExitType = FunctionType::get(Type::getVoidTy(TheContext), ExitArgs, false);
+    ExitFunc = TheModule.getOrInsertFunction("exit", ExitType);
+
+    DivZeroMsg = Builder.CreateGlobalStringPtr("[Fatal] line %d: Division by zero\n", "err_div_zero", 0, &TheModule);
+    OutOfBoundsMsg = Builder.CreateGlobalStringPtr("[Fatal] line %d: Array index out of bounds\n", "err_bounds", 0, &TheModule);
+}
+
+void RuntimeCheck::emitErrorAndExit(Value *Condition, Value *Msg, int Line) {
+    Function *TheFunction = Builder.GetInsertBlock()->getParent();
+    
+    BasicBlock *FailBB = BasicBlock::Create(TheContext, "check_fail", TheFunction);
+    BasicBlock *ContBB = BasicBlock::Create(TheContext, "check_cont", TheFunction);
+
+    Builder.CreateCondBr(Condition, FailBB, ContBB);
+
+    Builder.SetInsertPoint(FailBB);
+    std::vector<Value*> PrintArgs;
+    PrintArgs.push_back(Msg);
+    PrintArgs.push_back(ConstantInt::get(TheContext, APInt(32, Line)));
+    Builder.CreateCall(PrintfFunc, PrintArgs);
+
+    Builder.CreateCall(ExitFunc, ConstantInt::get(TheContext, APInt(32, 1)));
+    Builder.CreateUnreachable();
+
+    Builder.SetInsertPoint(ContBB);
+}
+
+void RuntimeCheck::emitDivZeroCheck(Value *Divisor, int Line) {
+    Value *IsZero = Builder.CreateICmpEQ(Divisor, ConstantInt::get(TheContext, APInt(32, 0)), "is_zero");
+    emitErrorAndExit(IsZero, DivZeroMsg, Line);
+}
+
+void RuntimeCheck::emitIndexCheck(Value *Index, Value *Lower, Value *Upper, int Line) {
+    Value *TooLow = Builder.CreateICmpSLT(Index, Lower, "too_low");
+    Value *TooHigh = Builder.CreateICmpSGT(Index, Upper, "too_high");
+    Value *OutOfBounds = Builder.CreateOr(TooLow, TooHigh, "out_of_bounds");
+    
+    emitErrorAndExit(OutOfBounds, OutOfBoundsMsg, Line);
+}