Trying to implement "exceptions" with longjmp (does not work on Windows 64bit at least)

evmcc/Compiler.cpp

@@ -199,16 +199,20 @@ std::unique_ptr<llvm::Module> Compiler::compile(const dev::bytes& bytecode)
 
 	createBasicBlocks(bytecode);
 
+	// Prepare jump buffer
+	auto jmpBufStorageTy = llvm::ArrayType::get(Type::Byte, 2048);
+	auto jmpBufStorage = new llvm::GlobalVariable(*module, jmpBufStorageTy, false, llvm::GlobalVariable::PrivateLinkage, llvm::ConstantAggregateZero::get(jmpBufStorageTy), "jmpBuf");
+	jmpBufStorage->setAlignment(16);
+	auto jmpBuf = builder.CreateConstInBoundsGEP2_32(jmpBufStorage, 0, 0);
+
 	// Init runtime structures.
-	GasMeter gasMeter(builder, module.get());
+	GasMeter gasMeter(builder, module.get(), jmpBuf);
 	Memory memory(builder, module.get(), gasMeter);
 	Ext ext(builder, module.get());
 
-	// Jump to first instruction
+	// Create exception landing with setjmp and jump to first instruction
 	auto setjmpFunc = llvm::Intrinsic::getDeclaration(module.get(), llvm::Intrinsic::eh_sjlj_setjmp);
-	auto jmpBufTy = llvm::ArrayType::get(builder.getInt64Ty(), 5);
-	auto jmpBuf = new llvm::GlobalVariable(*module, jmpBufTy, false, llvm::GlobalVariable::PrivateLinkage, llvm::UndefValue::get(jmpBufTy), "jmpBuf");
-	auto setjmpRet = builder.CreateCall(setjmpFunc, builder.CreateBitCast(jmpBuf, Type::BytePtr));
+	auto setjmpRet = builder.CreateCall(setjmpFunc, jmpBuf);
 	auto isNormalFlow = builder.CreateICmpEQ(setjmpRet, builder.getInt32(0));
 	builder.CreateCondBr(isNormalFlow, basicBlocks.begin()->second, m_outOfGasBlock->llvm());
 

evmcc/ExecutionEngine.cpp

@@ -121,7 +121,9 @@ int ExecutionEngine::run(std::unique_ptr<llvm::Module> _module)
 		for (auto it = returnData.begin(), end = returnData.end(); it != end; ++it)
 			std::cout << std::hex << std::setw(2) << std::setfill('0') << (int)*it << " ";
 		std::cout << "]\n";
-	}	
+	}
+
+	std::cout << "RETURN CODE: " << (int)returnCode << std::endl;
 	return static_cast<int>(returnCode);
 }
 

evmcc/GasMeter.cpp

@@ -3,6 +3,7 @@
 
 #include <llvm/IR/GlobalVariable.h>
 #include <llvm/IR/Function.h>
+#include <llvm/IR/IntrinsicInst.h>
 
 #include <libevmface/Instruction.h>
 #include <libevm/FeeStructure.h>
@@ -77,7 +78,7 @@ bool isCostBlockEnd(Instruction _inst)
 
 }
 
-GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module):
+GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module, llvm::Value* _jmpBuf) :
 	m_builder(_builder)
 {
 	m_gas = new llvm::GlobalVariable(*_module, Type::i256, false, llvm::GlobalVariable::ExternalLinkage, nullptr, "gas");
@@ -88,9 +89,9 @@ GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module):
 	m_gasCheckFunc = llvm::Function::Create(llvm::FunctionType::get(Type::Void, Type::i256, false), llvm::Function::PrivateLinkage, "gas.check", _module);
 	InsertPointGuard guard(m_builder); 
 
-	auto checkBB = llvm::BasicBlock::Create(_builder.getContext(), "check", m_gasCheckFunc);
-	auto outOfGasBB = llvm::BasicBlock::Create(_builder.getContext(), "outOfGas", m_gasCheckFunc);
-	auto updateBB = llvm::BasicBlock::Create(_builder.getContext(), "update", m_gasCheckFunc);
+	auto checkBB = llvm::BasicBlock::Create(_builder.getContext(), "Check", m_gasCheckFunc);
+	auto outOfGasBB = llvm::BasicBlock::Create(_builder.getContext(), "OutOfGas", m_gasCheckFunc);
+	auto updateBB = llvm::BasicBlock::Create(_builder.getContext(), "Update", m_gasCheckFunc);
 
 	m_builder.SetInsertPoint(checkBB);
 	llvm::Value* cost = m_gasCheckFunc->arg_begin();
@@ -100,8 +101,10 @@ GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module):
 	m_builder.CreateCondBr(isOutOfGas, outOfGasBB, updateBB);
 
 	m_builder.SetInsertPoint(outOfGasBB);
-	m_builder.CreateCall(m_rtExit, Constant::get(ReturnCode::OutOfGas));
-	m_builder.CreateRetVoid();
+
+	auto longjmpFunc = llvm::Intrinsic::getDeclaration(_module, llvm::Intrinsic::eh_sjlj_longjmp);
+	m_builder.CreateCall(longjmpFunc, _jmpBuf);
+	m_builder.CreateUnreachable();
 
 	m_builder.SetInsertPoint(updateBB);
 	gas = m_builder.CreateSub(gas, cost);

evmcc/GasMeter.h

@@ -11,7 +11,7 @@ namespace evmcc
 class GasMeter
 {
 public:
-	GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* module);
+	GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module, llvm::Value* _jmpBuf);
 
 	GasMeter(const GasMeter&) = delete;
 	void operator=(GasMeter) = delete;