Merge pull request #2275 from ethereum/returndata_lll

Add RETURNDATACOPY and RETURNDATASIZE to assembly (and LLL)

13 files changed, 108 insertions, 6 deletions

diff --git a/Changelog.md b/Changelog.md
index b398e014..8f1fe045 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,14 +1,15 @@
 ### 0.4.12 (unreleased)
 
 Features:
- * Assembler: renamed ``SHA3`` to `KECCAK256``.
- * AST: export all attributes to Json format
+ * Assembly: renamed ``SHA3`` to `KECCAK256``.
+ * Assembly: Add ``RETURNDATASIZE`` and ``RETURNDATACOPY`` (EIP211) instructions.
+ * AST: export all attributes to JSON format.
  * Inline Assembly: Present proper error message when not supplying enough arguments to a functional
    instruction.
  * Inline Assembly: introduce ``keccak256`` as an opcode. ``sha3`` is still a valid alias.
 
 Bugfixes:
- * Unused variable warnings no longer issued for variables used inside inline assembly
+ * Unused variable warnings no longer issued for variables used inside inline assembly.
 
 ### 0.4.11 (2017-05-03)
 
diff --git a/docs/assembly.rst b/docs/assembly.rst
index 90e70031..cd3ff4c0 100644
--- a/docs/assembly.rst
+++ b/docs/assembly.rst
@@ -234,6 +234,10 @@ In the grammar, opcodes are represented as pre-defined identifiers.
 +-------------------------+------+-----------------------------------------------------------------+
 | extcodecopy(a, t, f, s) | `-`  | like codecopy(t, f, s) but take code at address a               |
 +-------------------------+------+-----------------------------------------------------------------+
+| returndatasize          |      | size of the last returndata                                     |
++-------------------------+------+-----------------------------------------------------------------+
+| returndatacopy(t, f, s) | `*`  | copy s bytes from returndata at position f to mem at position t |
++-------------------------+------+-----------------------------------------------------------------+
 | create(v, p, s)         |      | create new contract with code mem[p..(p+s)) and send v wei      |
 |                         |      | and return the new address                                      |
 +-------------------------+------+-----------------------------------------------------------------+
diff --git a/libevmasm/GasMeter.cpp b/libevmasm/GasMeter.cpp
index 260b7439..31a7d13e 100644
--- a/libevmasm/GasMeter.cpp
+++ b/libevmasm/GasMeter.cpp
@@ -103,6 +103,7 @@ GasMeter::GasConsumption GasMeter::estimateMax(AssemblyItem const& _item, bool _
 			break;
 		case Instruction::CALLDATACOPY:
 		case Instruction::CODECOPY:
+		case Instruction::RETURNDATACOPY:
 			gas += memoryGas(0, -2);
 			gas += wordGas(GasCosts::copyGas, m_state->relativeStackElement(-2));
 			break;
diff --git a/libevmasm/Instruction.cpp b/libevmasm/Instruction.cpp
index 25eab60b..af7e9ff9 100644
--- a/libevmasm/Instruction.cpp
+++ b/libevmasm/Instruction.cpp
@@ -67,6 +67,8 @@ const std::map<std::string, Instruction> dev::solidity::c_instructions =
 	{ "GASPRICE", Instruction::GASPRICE },
 	{ "EXTCODESIZE", Instruction::EXTCODESIZE },
 	{ "EXTCODECOPY", Instruction::EXTCODECOPY },
+	{ "RETURNDATASIZE", Instruction::RETURNDATASIZE },
+	{ "RETURNDATACOPY", Instruction::RETURNDATACOPY },
 	{ "BLOCKHASH", Instruction::BLOCKHASH },
 	{ "COINBASE", Instruction::COINBASE },
 	{ "TIMESTAMP", Instruction::TIMESTAMP },
@@ -203,6 +205,8 @@ static const std::map<Instruction, InstructionInfo> c_instructionInfo =
 	{ Instruction::GASPRICE,	{ "GASPRICE",		0, 0, 1, false, Tier::Base } },
 	{ Instruction::EXTCODESIZE,	{ "EXTCODESIZE",	0, 1, 1, false, Tier::ExtCode } },
 	{ Instruction::EXTCODECOPY,	{ "EXTCODECOPY",	0, 4, 0, true, Tier::ExtCode } },
+	{ Instruction::RETURNDATASIZE,	{"RETURNDATASIZE",	0, 0, 1, false, Tier::Base } },
+	{ Instruction::RETURNDATACOPY,	{"RETURNDATACOPY",	0, 3, 0, true, Tier::VeryLow } },
 	{ Instruction::BLOCKHASH,	{ "BLOCKHASH",		0, 1, 1, false, Tier::Ext } },
 	{ Instruction::COINBASE,	{ "COINBASE",		0, 0, 1, false, Tier::Base } },
 	{ Instruction::TIMESTAMP,	{ "TIMESTAMP",		0, 0, 1, false, Tier::Base } },
diff --git a/libevmasm/Instruction.h b/libevmasm/Instruction.h
index 09d1e58b..a8c3bf4a 100644
--- a/libevmasm/Instruction.h
+++ b/libevmasm/Instruction.h
@@ -77,6 +77,8 @@ enum class Instruction: uint8_t
 	GASPRICE,			///< get price of gas in current environment
 	EXTCODESIZE,		///< get external code size (from another contract)
 	EXTCODECOPY,		///< copy external code (from another contract)
+	RETURNDATASIZE,		///< get size of the last return data
+	RETURNDATACOPY,		///< copy last return data to memory
 
 	BLOCKHASH = 0x40,	///< get hash of most recent complete block
 	COINBASE,			///< get the block's coinbase address
diff --git a/libevmasm/SemanticInformation.cpp b/libevmasm/SemanticInformation.cpp
index 61586e7b..86feb1d2 100644
--- a/libevmasm/SemanticInformation.cpp
+++ b/libevmasm/SemanticInformation.cpp
@@ -143,6 +143,8 @@ bool SemanticInformation::isDeterministic(AssemblyItem const& _item)
 	case Instruction::MSIZE: // depends on previous writes and reads, not only on content
 	case Instruction::BALANCE: // depends on previous calls
 	case Instruction::EXTCODESIZE:
+	case Instruction::RETURNDATACOPY: // depends on previous calls
+	case Instruction::RETURNDATASIZE:
 		return false;
 	default:
 		return true;
@@ -156,6 +158,7 @@ bool SemanticInformation::invalidatesMemory(Instruction _instruction)
 	case Instruction::CALLDATACOPY:
 	case Instruction::CODECOPY:
 	case Instruction::EXTCODECOPY:
+	case Instruction::RETURNDATACOPY:
 	case Instruction::MSTORE:
 	case Instruction::MSTORE8:
 	case Instruction::CALL:
diff --git a/libsolidity/analysis/NameAndTypeResolver.cpp b/libsolidity/analysis/NameAndTypeResolver.cpp
index 2742dcf2..aac90311 100644
--- a/libsolidity/analysis/NameAndTypeResolver.cpp
+++ b/libsolidity/analysis/NameAndTypeResolver.cpp
@@ -26,6 +26,8 @@
 #include <libsolidity/analysis/TypeChecker.h>
 #include <libsolidity/interface/ErrorReporter.h>
 
+#include <boost/algorithm/string.hpp>
+
 using namespace std;
 
 namespace dev
@@ -232,6 +234,26 @@ vector<Declaration const*> NameAndTypeResolver::cleanedDeclarations(
 	return uniqueFunctions;
 }
 
+void NameAndTypeResolver::warnVariablesNamedLikeInstructions()
+{
+	for (auto const& instruction: c_instructions)
+	{
+		string const instructionName{boost::algorithm::to_lower_copy(instruction.first)};
+		auto declarations = nameFromCurrentScope(instructionName);
+		for (Declaration const* const declaration: declarations)
+		{
+			solAssert(!!declaration, "");
+			if (dynamic_cast<MagicVariableDeclaration const* const>(declaration))
+				// Don't warn the user for what the user did not.
+				continue;
+			m_errorReporter.warning(
+				declaration->location(),
+				"Variable is shadowed in inline assembly by an instruction of the same name"
+			);
+		}
+	}
+}
+
 bool NameAndTypeResolver::resolveNamesAndTypesInternal(ASTNode& _node, bool _resolveInsideCode)
 {
 	if (ContractDefinition* contract = dynamic_cast<ContractDefinition*>(&_node))
diff --git a/libsolidity/analysis/NameAndTypeResolver.h b/libsolidity/analysis/NameAndTypeResolver.h
index 0441867d..84628778 100644
--- a/libsolidity/analysis/NameAndTypeResolver.h
+++ b/libsolidity/analysis/NameAndTypeResolver.h
@@ -90,6 +90,9 @@ public:
 		std::vector<Declaration const*> const& _declarations
 	);
 
+	/// Generate and store warnings about variables that are named like instructions.
+	void warnVariablesNamedLikeInstructions();
+
 private:
 	/// Internal version of @a resolveNamesAndTypes (called from there) throws exceptions on fatal errors.
 	bool resolveNamesAndTypesInternal(ASTNode& _node, bool _resolveInsideCode = true);
diff --git a/libsolidity/analysis/ReferencesResolver.cpp b/libsolidity/analysis/ReferencesResolver.cpp
index edf2fc02..2a5f27df 100644
--- a/libsolidity/analysis/ReferencesResolver.cpp
+++ b/libsolidity/analysis/ReferencesResolver.cpp
@@ -162,6 +162,8 @@ void ReferencesResolver::endVisit(ArrayTypeName const& _typeName)
 
 bool ReferencesResolver::visit(InlineAssembly const& _inlineAssembly)
 {
+	m_resolver.warnVariablesNamedLikeInstructions();
+
 	// Errors created in this stage are completely ignored because we do not yet know
 	// the type and size of external identifiers, which would result in false errors.
 	// The only purpose of this step is to fill the inline assembly annotation with
diff --git a/libsolidity/inlineasm/AsmAnalysis.cpp b/libsolidity/inlineasm/AsmAnalysis.cpp
index 13852880..36ac0e75 100644
--- a/libsolidity/inlineasm/AsmAnalysis.cpp
+++ b/libsolidity/inlineasm/AsmAnalysis.cpp
@@ -65,6 +65,7 @@ bool AsmAnalyzer::operator()(assembly::Instruction const& _instruction)
 	auto const& info = instructionInfo(_instruction.instruction);
 	m_stackHeight += info.ret - info.args;
 	m_info.stackHeightInfo[&_instruction] = m_stackHeight;
+	warnOnFutureInstruction(_instruction.instruction, _instruction.location);
 	return true;
 }
 
@@ -149,6 +150,7 @@ bool AsmAnalyzer::operator()(FunctionalInstruction const& _instr)
 	if (!(*this)(_instr.instruction))
 		success = false;
 	m_info.stackHeightInfo[&_instr] = m_stackHeight;
+	warnOnFutureInstruction(_instr.instruction.instruction, _instr.location);
 	return success;
 }
 
@@ -431,7 +433,6 @@ Scope& AsmAnalyzer::scope(Block const* _block)
 	solAssert(scopePtr, "Scope requested but not present.");
 	return *scopePtr;
 }
-
 void AsmAnalyzer::expectValidType(string const& type, SourceLocation const& _location)
 {
 	if (!m_julia)
@@ -443,3 +444,20 @@ void AsmAnalyzer::expectValidType(string const& type, SourceLocation const& _loc
 			"\"" + type + "\" is not a valid type (user defined types are not yet supported)."
 		);
 }
+
+void AsmAnalyzer::warnOnFutureInstruction(solidity::Instruction _instr, SourceLocation const& _location)
+{
+	switch (_instr)
+	{
+	case solidity::Instruction::RETURNDATASIZE:
+	case solidity::Instruction::RETURNDATACOPY:
+		m_errorReporter.warning(
+			_location,
+			"The RETURNDATASIZE/RETURNDATACOPY instructions are only available after "
+			"the Metropolis hard fork. Before that they act as an invalid instruction."
+		);
+		break;
+	default:
+		break;
+	}
+}
diff --git a/libsolidity/inlineasm/AsmAnalysis.h b/libsolidity/inlineasm/AsmAnalysis.h
index e7748bcf..55b409ba 100644
--- a/libsolidity/inlineasm/AsmAnalysis.h
+++ b/libsolidity/inlineasm/AsmAnalysis.h
@@ -97,6 +97,7 @@ private:
 
 	Scope& scope(assembly::Block const* _block);
 	void expectValidType(std::string const& type, SourceLocation const& _location);
+	void warnOnFutureInstruction(solidity::Instruction _instr, SourceLocation const& _location);
 
 	int m_stackHeight = 0;
 	julia::ExternalIdentifierAccess::Resolver m_resolver;
diff --git a/test/libsolidity/InlineAssembly.cpp b/test/libsolidity/InlineAssembly.cpp
index d2d320db..435c3dad 100644
--- a/test/libsolidity/InlineAssembly.cpp
+++ b/test/libsolidity/InlineAssembly.cpp
@@ -542,6 +542,26 @@ BOOST_AUTO_TEST_CASE(keccak256)
 	BOOST_CHECK(successAssemble("{ pop(sha3(0, 0)) }"));
 }
 
+BOOST_AUTO_TEST_CASE(returndatasize)
+{
+	BOOST_CHECK(successAssemble("{ let r := returndatasize }"));
+}
+
+BOOST_AUTO_TEST_CASE(returndatasize_functional)
+{
+	BOOST_CHECK(successAssemble("{ let r := returndatasize() }"));
+}
+
+BOOST_AUTO_TEST_CASE(returndatacopy)
+{
+	BOOST_CHECK(successAssemble("{ 64 32 0 returndatacopy }"));
+}
+
+BOOST_AUTO_TEST_CASE(returndatacopy_functional)
+{
+	BOOST_CHECK(successAssemble("{ returndatacopy(0, 32, 64) }"));
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index db5b9bf8..ba2ade66 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -193,11 +193,16 @@ CHECK_ERROR_OR_WARNING(text, type, substring, false, false)
 #define CHECK_ERROR_ALLOW_MULTI(text, type, substring) \
 CHECK_ERROR_OR_WARNING(text, type, substring, false, true)
 
-// [checkWarning(text, type, substring)] asserts that the compilation down to typechecking
-// emits a warning of type [type] and with a message containing [substring].
+// [checkWarning(text, substring)] asserts that the compilation down to typechecking
+// emits a warning and with a message containing [substring].
 #define CHECK_WARNING(text, substring) \
 CHECK_ERROR_OR_WARNING(text, Warning, substring, true, false)
 
+// [checkWarningAllowMulti(text, substring)] aserts that the compilation down to typechecking
+// emits a warning and with a message containing [substring].
+#define CHECK_WARNING_ALLOW_MULTI(text, substring) \
+CHECK_ERROR_OR_WARNING(text, Warning, substring, true, true)
+
 // [checkSuccess(text)] asserts that the compilation down to typechecking succeeds.
 #define CHECK_SUCCESS(text) do { BOOST_CHECK(success((text))); } while(0)
 
@@ -5780,6 +5785,22 @@ BOOST_AUTO_TEST_CASE(no_unused_inline_asm)
 	CHECK_SUCCESS_NO_WARNINGS(text);
 }
 
+BOOST_AUTO_TEST_CASE(returndatacopy_as_variable)
+{
+	char const* text = R"(
+		contract c { function f() { uint returndatasize; assembly { returndatasize }}}
+	)";
+	CHECK_WARNING_ALLOW_MULTI(text, "Variable is shadowed in inline assembly by an instruction of the same name");
+}
+
+BOOST_AUTO_TEST_CASE(shadowing_warning_can_be_removed)
+{
+	char const* text = R"(
+		contract C {function f() {assembly {}}}
+	)";
+	CHECK_SUCCESS_NO_WARNINGS(text);
+}
+
 
 
 BOOST_AUTO_TEST_SUITE_END()