Working longjmp solution

[#80660432]

evmcc/Compiler.cpp

@@ -199,22 +199,12 @@ 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(), jmpBuf);
+	GasMeter gasMeter(builder, module.get());
 	Memory memory(builder, module.get(), gasMeter);
 	Ext ext(builder, module.get());
 
-	// Create exception landing with setjmp and jump to first instruction
-	auto setjmpFunc = llvm::Intrinsic::getDeclaration(module.get(), llvm::Intrinsic::eh_sjlj_setjmp);
-	auto setjmpRet = builder.CreateCall(setjmpFunc, jmpBuf);
-	auto isNormalFlow = builder.CreateICmpEQ(setjmpRet, builder.getInt32(0));
-	builder.CreateCondBr(isNormalFlow, basicBlocks.begin()->second, m_outOfGasBlock->llvm());
+	builder.CreateBr(basicBlocks.begin()->second);
 
 	for (auto basicBlockPairIt = basicBlocks.begin(); basicBlockPairIt != basicBlocks.end(); ++basicBlockPairIt)
 	{

evmcc/ExecutionEngine.cpp

@@ -1,6 +1,8 @@
 
 #include "ExecutionEngine.h"
 
+#include <csetjmp>
+
 #include <llvm/IR/LLVMContext.h>
 #include <llvm/IR/Module.h>
 #include <llvm/ADT/Triple.h>
@@ -27,6 +29,8 @@ ExecutionEngine::ExecutionEngine()
 
 }
 
+extern "C" { EXPORT std::jmp_buf* rt_jmpBuf; }
+
 
 int ExecutionEngine::run(std::unique_ptr<llvm::Module> _module)
 {
@@ -101,17 +105,17 @@ int ExecutionEngine::run(std::unique_ptr<llvm::Module> _module)
 		exit(1);
 	}
 
-
 	ReturnCode returnCode;
-	try
+	std::jmp_buf buf;
+	auto r = setjmp(buf);
+	if (r == 0)
 	{
+		rt_jmpBuf = &buf;
 		auto result = exec->runFunction(entryFunc, {});
 		returnCode = static_cast<ReturnCode>(result.IntVal.getZExtValue());
 	}
-	catch (const dev::eth::OutOfGas&)
-	{
-		returnCode = ReturnCode::OutOfGas;
-	}
+	else
+		returnCode = static_cast<ReturnCode>(r);
 
 	gas = static_cast<decltype(gas)>(Runtime::getGas());
 	

evmcc/GasMeter.cpp

@@ -78,7 +78,7 @@ bool isCostBlockEnd(Instruction _inst)
 
 }
 
-GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module, llvm::Value* _jmpBuf) :
+GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module) :
 	m_builder(_builder)
 {
 	m_gas = new llvm::GlobalVariable(*_module, Type::i256, false, llvm::GlobalVariable::ExternalLinkage, nullptr, "gas");
@@ -102,8 +102,11 @@ GasMeter::GasMeter(llvm::IRBuilder<>& _builder, llvm::Module* _module, llvm::Val
 
 	m_builder.SetInsertPoint(outOfGasBB);
 
-	auto longjmpFunc = llvm::Intrinsic::getDeclaration(_module, llvm::Intrinsic::eh_sjlj_longjmp);
-	m_builder.CreateCall(longjmpFunc, _jmpBuf);
+	//auto longjmpFunc = llvm::Intrinsic::getDeclaration(_module, llvm::Intrinsic::eh_sjlj_longjmp);
+	auto extJmpBuf = new llvm::GlobalVariable(*_module, Type::BytePtr, false, llvm::GlobalVariable::ExternalLinkage, nullptr, "rt_jmpBuf");
+	llvm::Type* args[] = {Type::BytePtr, m_builder.getInt32Ty()};
+	auto longjmpNative = llvm::Function::Create(llvm::FunctionType::get(Type::Void, args, false), llvm::Function::ExternalLinkage, "longjmp", _module);
+	m_builder.CreateCall2(longjmpNative, m_builder.CreateLoad(extJmpBuf), Constant::get(ReturnCode::OutOfGas));
 	m_builder.CreateUnreachable();
 
 	m_builder.SetInsertPoint(updateBB);

evmcc/GasMeter.h

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