Change translation of implicit throws (issue #1589).

This adds a new invalid instruction that is used for encoding
implicit throws that are emitted by the compiler. This makes it
possible to distinguish such runtime errors from user-provided,
explicit throws.

10 files changed, 49 insertions, 17 deletions

diff --git a/libevmasm/Instruction.cpp b/libevmasm/Instruction.cpp
index 17445c59..ea5b5a10 100644
--- a/libevmasm/Instruction.cpp
+++ b/libevmasm/Instruction.cpp
@@ -154,6 +154,7 @@ const std::map<std::string, Instruction> dev::solidity::c_instructions =
 	{ "LOG2", Instruction::LOG2 },
 	{ "LOG3", Instruction::LOG3 },
 	{ "LOG4", Instruction::LOG4 },
+	{ "INVALID", Instruction::INVALID },
 	{ "CREATE", Instruction::CREATE },
 	{ "CALL", Instruction::CALL },
 	{ "CALLCODE", Instruction::CALLCODE },
@@ -288,6 +289,7 @@ static const std::map<Instruction, InstructionInfo> c_instructionInfo =
 	{ Instruction::LOG2,		{ "LOG2",			0, 4, 0, true, Tier::Special } },
 	{ Instruction::LOG3,		{ "LOG3",			0, 5, 0, true, Tier::Special } },
 	{ Instruction::LOG4,		{ "LOG4",			0, 6, 0, true, Tier::Special } },
+	{ Instruction::INVALID,		{ "INVALID",		0, 0, 0, true, Tier::Zero } },
 	{ Instruction::CREATE,		{ "CREATE",			0, 3, 1, true, Tier::Special } },
 	{ Instruction::CALL,		{ "CALL",			0, 7, 1, true, Tier::Special } },
 	{ Instruction::CALLCODE,	{ "CALLCODE",		0, 7, 1, true, Tier::Special } },
diff --git a/libevmasm/Instruction.h b/libevmasm/Instruction.h
index 2dd451cd..7432f04d 100644
--- a/libevmasm/Instruction.h
+++ b/libevmasm/Instruction.h
@@ -171,6 +171,8 @@ enum class Instruction: uint8_t
 	LOG3,				///< Makes a log entry; 3 topics.
 	LOG4,				///< Makes a log entry; 4 topics.
 
+	INVALID = 0xef,		///< invalid instruction for expressing runtime errors (e.g., division-by-zero)
+
 	CREATE = 0xf0,		///< create a new account with associated code
 	CALL,				///< message-call into an account
 	CALLCODE,			///< message-call with another account's code only
diff --git a/libsolidity/codegen/ArrayUtils.cpp b/libsolidity/codegen/ArrayUtils.cpp
index 4d100d1d..bdd29abd 100644
--- a/libsolidity/codegen/ArrayUtils.cpp
+++ b/libsolidity/codegen/ArrayUtils.cpp
@@ -901,7 +901,7 @@ void ArrayUtils::accessIndex(ArrayType const& _arrayType, bool _doBoundsCheck) c
 		// check out-of-bounds access
 		m_context << Instruction::DUP2 << Instruction::LT << Instruction::ISZERO;
 		// out-of-bounds access throws exception
-		m_context.appendConditionalJumpTo(m_context.errorTag());
+		m_context.appendConditionalInvalid();
 	}
 	if (location == DataLocation::CallData && _arrayType.isDynamicallySized())
 		// remove length if present
diff --git a/libsolidity/codegen/CompilerContext.cpp b/libsolidity/codegen/CompilerContext.cpp
index e26f96e8..45450350 100644
--- a/libsolidity/codegen/CompilerContext.cpp
+++ b/libsolidity/codegen/CompilerContext.cpp
@@ -215,6 +215,18 @@ CompilerContext& CompilerContext::appendJump(eth::AssemblyItem::JumpType _jumpTy
 	return *this << item;
 }
 
+CompilerContext& CompilerContext::appendInvalid()
+{
+	return *this << Instruction::INVALID;
+}
+
+CompilerContext& CompilerContext::appendConditionalInvalid()
+{
+	eth::AssemblyItem falseTag = appendConditionalJump();
+	eth::AssemblyItem endTag = appendJumpToNew();
+	return *this << falseTag << Instruction::INVALID << endTag;
+}
+
 void CompilerContext::resetVisitedNodes(ASTNode const* _node)
 {
 	stack<ASTNode const*> newStack;
diff --git a/libsolidity/codegen/CompilerContext.h b/libsolidity/codegen/CompilerContext.h
index f024b010..58d6cb2a 100644
--- a/libsolidity/codegen/CompilerContext.h
+++ b/libsolidity/codegen/CompilerContext.h
@@ -127,6 +127,10 @@ public:
 	eth::AssemblyItem appendJumpToNew() { return m_asm->appendJump().tag(); }
 	/// Appends a JUMP to a tag already on the stack
 	CompilerContext&  appendJump(eth::AssemblyItem::JumpType _jumpType = eth::AssemblyItem::JumpType::Ordinary);
+	/// Appends an INVALID instruction
+	CompilerContext&  appendInvalid();
+	/// Appends a conditional INVALID instruction
+	CompilerContext&  appendConditionalInvalid();
 	/// Returns an "ErrorTag"
 	eth::AssemblyItem errorTag() { return m_asm->errorTag(); }
 	/// Appends a JUMP to a specific tag
diff --git a/libsolidity/codegen/CompilerUtils.cpp b/libsolidity/codegen/CompilerUtils.cpp
index caf3b1ac..67877bbf 100644
--- a/libsolidity/codegen/CompilerUtils.cpp
+++ b/libsolidity/codegen/CompilerUtils.cpp
@@ -468,7 +468,7 @@ void CompilerUtils::convertType(Type const& _typeOnStack, Type const& _targetTyp
 			EnumType const& enumType = dynamic_cast<decltype(enumType)>(_typeOnStack);
 			solAssert(enumType.numberOfMembers() > 0, "empty enum should have caused a parser error.");
 			m_context << u256(enumType.numberOfMembers() - 1) << Instruction::DUP2 << Instruction::GT;
-			m_context.appendConditionalJumpTo(m_context.errorTag());
+			m_context.appendConditionalInvalid();
 			enumOverflowCheckPending = false;
 		}
 		break;
@@ -497,7 +497,7 @@ void CompilerUtils::convertType(Type const& _typeOnStack, Type const& _targetTyp
 			EnumType const& enumType = dynamic_cast<decltype(enumType)>(_targetType);
 			solAssert(enumType.numberOfMembers() > 0, "empty enum should have caused a parser error.");
 			m_context << u256(enumType.numberOfMembers() - 1) << Instruction::DUP2 << Instruction::GT;
-			m_context.appendConditionalJumpTo(m_context.errorTag());
+			m_context.appendConditionalInvalid();
 			enumOverflowCheckPending = false;
 		}
 		else if (targetTypeCategory == Type::Category::FixedPoint)
@@ -807,7 +807,7 @@ void CompilerUtils::pushZeroValue(Type const& _type)
 	{
 		if (funType->location() == FunctionType::Location::Internal)
 		{
-			m_context << m_context.errorTag();
+			m_context.appendInvalid();
 			return;
 		}
 	}
diff --git a/libsolidity/codegen/ContractCompiler.cpp b/libsolidity/codegen/ContractCompiler.cpp
index 9dc1fb37..56d03a05 100644
--- a/libsolidity/codegen/ContractCompiler.cpp
+++ b/libsolidity/codegen/ContractCompiler.cpp
@@ -106,7 +106,7 @@ void ContractCompiler::appendCallValueCheck()
 {
 	// Throw if function is not payable but call contained ether.
 	m_context << Instruction::CALLVALUE;
-	m_context.appendConditionalJumpTo(m_context.errorTag());
+	m_context.appendConditionalInvalid();
 }
 
 void ContractCompiler::appendInitAndConstructorCode(ContractDefinition const& _contract)
@@ -271,7 +271,7 @@ void ContractCompiler::appendFunctionSelector(ContractDefinition const& _contrac
 		appendReturnValuePacker(FunctionType(*fallback).returnParameterTypes(), _contract.isLibrary());
 	}
 	else
-		m_context.appendJumpTo(m_context.errorTag());
+		m_context.appendInvalid();
 
 	for (auto const& it: interfaceFunctions)
 	{
@@ -918,7 +918,9 @@ eth::AssemblyPointer ContractCompiler::cloneRuntime()
 	a << Instruction::DELEGATECALL;
 	//Propagate error condition (if DELEGATECALL pushes 0 on stack).
 	a << Instruction::ISZERO;
-	a.appendJumpI(a.errorTag());
+	eth::AssemblyItem falseTag = a.appendJumpI();
+	eth::AssemblyItem endTag = a.appendJump().tag();
+	a << falseTag << Instruction::INVALID << endTag;
 	//@todo adjust for larger return values, make this dynamic.
 	a << u256(0x20) << u256(0) << Instruction::RETURN;
 	return make_shared<eth::Assembly>(a);
diff --git a/libsolidity/codegen/ExpressionCompiler.cpp b/libsolidity/codegen/ExpressionCompiler.cpp
index bda4e04d..b66a3e12 100644
--- a/libsolidity/codegen/ExpressionCompiler.cpp
+++ b/libsolidity/codegen/ExpressionCompiler.cpp
@@ -585,7 +585,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			m_context << Instruction::CREATE;
 			// Check if zero (out of stack or not enough balance).
 			m_context << Instruction::DUP1 << Instruction::ISZERO;
-			m_context.appendConditionalJumpTo(m_context.errorTag());
+			m_context.appendConditionalInvalid();
 			if (function.valueSet())
 				m_context << swapInstruction(1) << Instruction::POP;
 			break;
@@ -1234,7 +1234,7 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 		m_context << u256(fixedBytesType.numBytes());
 		m_context << Instruction::DUP2 << Instruction::LT << Instruction::ISZERO;
 		// out-of-bounds access throws exception
-		m_context.appendConditionalJumpTo(m_context.errorTag());
+		m_context.appendConditionalInvalid();
 
 		m_context << Instruction::BYTE;
 		m_context << (u256(1) << (256 - 8)) << Instruction::MUL;
@@ -1416,7 +1416,7 @@ void ExpressionCompiler::appendArithmeticOperatorCode(Token::Value _operator, Ty
 	{
 		// Test for division by zero
 		m_context << Instruction::DUP2 << Instruction::ISZERO;
-		m_context.appendConditionalJumpTo(m_context.errorTag());
+		m_context.appendConditionalInvalid();
 
 		if (_operator == Token::Div)
 			m_context << (c_isSigned ? Instruction::SDIV : Instruction::DIV);
@@ -1477,7 +1477,7 @@ void ExpressionCompiler::appendShiftOperatorCode(Token::Value _operator, Type co
 	if (c_amountSigned)
 	{
 		m_context << u256(0) << Instruction::DUP3 << Instruction::SLT;
-		m_context.appendConditionalJumpTo(m_context.errorTag());
+		m_context.appendConditionalInvalid();
 	}
 
 	switch (_operator)
@@ -1663,7 +1663,7 @@ void ExpressionCompiler::appendExternalFunctionCall(
 	if (funKind == FunctionKind::External || funKind == FunctionKind::CallCode || funKind == FunctionKind::DelegateCall)
 	{
 		m_context << Instruction::DUP1 << Instruction::EXTCODESIZE << Instruction::ISZERO;
-		m_context.appendConditionalJumpTo(m_context.errorTag());
+		m_context.appendConditionalInvalid();
 		existenceChecked = true;
 	}
 
@@ -1699,7 +1699,7 @@ void ExpressionCompiler::appendExternalFunctionCall(
 	{
 		//Propagate error condition (if CALL pushes 0 on stack).
 		m_context << Instruction::ISZERO;
-		m_context.appendConditionalJumpTo(m_context.errorTag());
+		m_context.appendConditionalInvalid();
 	}
 
 	utils().popStackSlots(remainsSize);
diff --git a/test/libsolidity/Assembly.cpp b/test/libsolidity/Assembly.cpp
index 155dd5c9..aed3c854 100644
--- a/test/libsolidity/Assembly.cpp
+++ b/test/libsolidity/Assembly.cpp
@@ -116,8 +116,8 @@ BOOST_AUTO_TEST_CASE(location_test)
 	shared_ptr<string const> n = make_shared<string>("");
 	AssemblyItems items = compileContract(sourceCode);
 	vector<SourceLocation> locations =
-		vector<SourceLocation>(18, SourceLocation(2, 75, n)) +
-		vector<SourceLocation>(27, SourceLocation(20, 72, n)) +
+		vector<SourceLocation>(17, SourceLocation(2, 75, n)) +
+		vector<SourceLocation>(32, SourceLocation(20, 72, n)) +
 		vector<SourceLocation>{SourceLocation(42, 51, n), SourceLocation(65, 67, n)} +
 		vector<SourceLocation>(2, SourceLocation(58, 67, n)) +
 		vector<SourceLocation>(3, SourceLocation(20, 72, n));
diff --git a/test/libsolidity/SolidityExpressionCompiler.cpp b/test/libsolidity/SolidityExpressionCompiler.cpp
index 0c5a09c3..ca630169 100644
--- a/test/libsolidity/SolidityExpressionCompiler.cpp
+++ b/test/libsolidity/SolidityExpressionCompiler.cpp
@@ -337,13 +337,23 @@ BOOST_AUTO_TEST_CASE(arithmetics)
 					   byte(Instruction::ADD),
 					   byte(Instruction::DUP2),
 					   byte(Instruction::ISZERO),
-					   byte(Instruction::PUSH1), 0x0,
+					   byte(Instruction::PUSH1), 0x1e,
 					   byte(Instruction::JUMPI),
+					   byte(Instruction::PUSH1), 0x20,
+					   byte(Instruction::JUMP),
+					   byte(Instruction::JUMPDEST),
+					   byte(Instruction::INVALID),
+					   byte(Instruction::JUMPDEST),
 					   byte(Instruction::MOD),
 					   byte(Instruction::DUP2),
 					   byte(Instruction::ISZERO),
-					   byte(Instruction::PUSH1), 0x0,
+					   byte(Instruction::PUSH1), 0x2a,
 					   byte(Instruction::JUMPI),
+					   byte(Instruction::PUSH1), 0x2c,
+					   byte(Instruction::JUMP),
+					   byte(Instruction::JUMPDEST),
+					   byte(Instruction::INVALID),
+					   byte(Instruction::JUMPDEST),
 					   byte(Instruction::DIV),
 					   byte(Instruction::MUL)});
 	BOOST_CHECK_EQUAL_COLLECTIONS(code.begin(), code.end(), expectation.begin(), expectation.end());