Only generate sort/search code when interface functions exist

Changelog.md

@@ -6,6 +6,7 @@ Language Features:
 
 Compiler Features:
  * Inline Assembly: Improve error messages around invalid function argument count.
+ * Code Generator: Only check callvalue once if all functions are non-payable.
  * Code Generator: Use codecopy for string constants more aggressively.
  * Code Generator: Use binary search for dispatch function if more efficient. The size/speed tradeoff can be tuned using ``--optimize-runs``.
  * Compiler Interface: Disallow unknown keys in standard JSON input.

libsolidity/codegen/ContractCompiler.cpp

@@ -331,6 +331,25 @@ void ContractCompiler::appendInternalSelector(
 	}
 }
 
+namespace
+{
+
+// Helper function to check if any function is payable
+bool hasPayableFunctions(ContractDefinition const& _contract)
+{
+	FunctionDefinition const* fallback = _contract.fallbackFunction();
+	if (fallback && fallback->isPayable())
+		return true;
+
+	for (auto const& it: _contract.interfaceFunctions())
+		if (it.second->isPayable())
+			return true;
+
+	return false;
+}
+
+}
+
 void ContractCompiler::appendFunctionSelector(ContractDefinition const& _contract)
 {
 	map<FixedHash<4>, FunctionTypePointer> interfaceFunctions = _contract.interfaceFunctions();
@@ -342,6 +361,15 @@ void ContractCompiler::appendFunctionSelector(ContractDefinition const& _contrac
 	}
 
 	FunctionDefinition const* fallback = _contract.fallbackFunction();
+	solAssert(!_contract.isLibrary() || !fallback, "Libraries can't have fallback functions");
+
+	bool needToAddCallvalueCheck = true;
+	if (!hasPayableFunctions(_contract) && !interfaceFunctions.empty() && !_contract.isLibrary())
+	{
+		appendCallValueCheck();
+		needToAddCallvalueCheck = false;
+	}
+
 	eth::AssemblyItem notFound = m_context.newTag();
 	// directly jump to fallback if the data is too short to contain a function selector
 	// also guards against short data
@@ -350,23 +378,26 @@ void ContractCompiler::appendFunctionSelector(ContractDefinition const& _contrac
 
 	// retrieve the function signature hash from the calldata
 	if (!interfaceFunctions.empty())
+	{
 		CompilerUtils(m_context).loadFromMemory(0, IntegerType(CompilerUtils::dataStartOffset * 8), true);
 
-	// stack now is: <can-call-non-view-functions>? <funhash>
-	vector<FixedHash<4>> sortedIDs;
-	for (auto const& it: interfaceFunctions)
-	{
-		callDataUnpackerEntryPoints.insert(std::make_pair(it.first, m_context.newTag()));
-		sortedIDs.emplace_back(it.first);
+		// stack now is: <can-call-non-view-functions>? <funhash>
+		vector<FixedHash<4>> sortedIDs;
+		for (auto const& it: interfaceFunctions)
+		{
+			callDataUnpackerEntryPoints.emplace(it.first, m_context.newTag());
+			sortedIDs.emplace_back(it.first);
+		}
+		std::sort(sortedIDs.begin(), sortedIDs.end());
+		appendInternalSelector(callDataUnpackerEntryPoints, sortedIDs, notFound, m_optimise_runs);
 	}
-	std::sort(sortedIDs.begin(), sortedIDs.end());
-	appendInternalSelector(callDataUnpackerEntryPoints, sortedIDs, notFound, m_optimise_runs);
 
 	m_context << notFound;
+
 	if (fallback)
 	{
 		solAssert(!_contract.isLibrary(), "");
-		if (!fallback->isPayable())
+		if (!fallback->isPayable() && needToAddCallvalueCheck)
 			appendCallValueCheck();
 
 		solAssert(fallback->isFallback(), "");
@@ -396,7 +427,7 @@ void ContractCompiler::appendFunctionSelector(ContractDefinition const& _contrac
 		m_context.setStackOffset(0);
 		// We have to allow this for libraries, because value of the previous
 		// call is still visible in the delegatecall.
-		if (!functionType->isPayable() && !_contract.isLibrary())
+		if (!functionType->isPayable() && !_contract.isLibrary() && needToAddCallvalueCheck)
 			appendCallValueCheck();
 
 		// Return tag is used to jump out of the function.

test/libsolidity/Assembly.cpp

@@ -165,14 +165,14 @@ BOOST_AUTO_TEST_CASE(location_test)
 	auto codegenCharStream = make_shared<CharStream>("", "--CODEGEN--");
 
 	vector<SourceLocation> locations =
-		vector<SourceLocation>(hasShifts ? 21 : 22, SourceLocation(2, 82, sourceCode)) +
-		vector<SourceLocation>(2, SourceLocation(20, 79, sourceCode)) +
-		vector<SourceLocation>(1, SourceLocation(8, 17,  codegenCharStream)) +
-		vector<SourceLocation>(3, SourceLocation(5, 7,   codegenCharStream)) +
+		vector<SourceLocation>(4, SourceLocation(2, 82, sourceCode)) +
+		vector<SourceLocation>(1, SourceLocation(8, 17, codegenCharStream)) +
+		vector<SourceLocation>(3, SourceLocation(5, 7, codegenCharStream)) +
 		vector<SourceLocation>(1, SourceLocation(30, 31, codegenCharStream)) +
 		vector<SourceLocation>(1, SourceLocation(27, 28, codegenCharStream)) +
 		vector<SourceLocation>(1, SourceLocation(20, 32, codegenCharStream)) +
-		vector<SourceLocation>(1, SourceLocation(5, 7,   codegenCharStream)) +
+		vector<SourceLocation>(1, SourceLocation(5, 7, codegenCharStream)) +
+		vector<SourceLocation>(hasShifts ? 19 : 20, SourceLocation(2, 82, sourceCode)) +
 		vector<SourceLocation>(24, SourceLocation(20, 79, sourceCode)) +
 		vector<SourceLocation>(1, SourceLocation(49, 58, sourceCode)) +
 		vector<SourceLocation>(1, SourceLocation(72, 74, sourceCode)) +

test/libsolidity/GasCosts.cpp

@@ -82,6 +82,49 @@ BOOST_AUTO_TEST_CASE(string_storage)
 	}
 }
 
+BOOST_AUTO_TEST_CASE(single_callvaluecheck)
+{
+	string sourceCode = R"(
+		// All functions nonpayable, we can check callvalue at the beginning
+		contract Nonpayable {
+			address a;
+			function f(address b) public {
+				a = b;
+			}
+			function f1(address b) public pure returns (uint c) {
+				return uint(b) + 2;
+			}
+			function f2(address b) public pure returns (uint) {
+				return uint(b) + 8;
+			}
+			function f3(address, uint c) pure public returns (uint) {
+				return c - 5;
+			}
+		}
+		// At least on payable function, we cannot do the optimization.
+		contract Payable {
+			address a;
+			function f(address b) public {
+				a = b;
+			}
+			function f1(address b) public pure returns (uint c) {
+				return uint(b) + 2;
+			}
+			function f2(address b) public pure returns (uint) {
+				return uint(b) + 8;
+			}
+			function f3(address, uint c) payable public returns (uint) {
+				return c - 5;
+			}
+		}
+	)";
+	compileAndRun(sourceCode);
+	size_t bytecodeSizeNonpayable = m_compiler.object("Nonpayable").bytecode.size();
+	size_t bytecodeSizePayable = m_compiler.object("Payable").bytecode.size();
+
+	BOOST_CHECK_EQUAL(bytecodeSizePayable - bytecodeSizeNonpayable, 26);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }