Add assembly support for EXTCODEHASH (EIP-1052)

Changelog.md

@@ -90,6 +90,7 @@ Language Features:
 Compiler Features:
  * C API (``libsolc``): Export the ``solidity_license``, ``solidity_version`` and ``solidity_compile`` methods.
  * Code Generator: ``CREATE2`` instruction has been updated to match EIP1014 (aka "Skinny CREATE2"). It also is accepted as part of Constantinople.
+ * Code Generator: ``EXTCODEHASH`` instruction has been added based on EIP1052.
  * Type Checker: Nicer error message when trying to reference overloaded identifiers in inline assembly.
  * Type Checker: Show named argument in case of error.
  * Type System: IntegerType is split into IntegerType and AddressType internally.

libevmasm/GasMeter.cpp

@@ -112,6 +112,7 @@ GasMeter::GasConsumption GasMeter::estimateMax(AssemblyItem const& _item, bool _
 			gas += wordGas(GasCosts::copyGas, m_state->relativeStackElement(-2));
 			break;
 		case Instruction::EXTCODESIZE:
+		case Instruction::EXTCODEHASH:
 			gas = GasCosts::extCodeGas(m_evmVersion);
 			break;
 		case Instruction::EXTCODECOPY:

libevmasm/Instruction.cpp

@@ -73,6 +73,7 @@ const std::map<std::string, Instruction> dev::solidity::c_instructions =
 	{ "EXTCODECOPY", Instruction::EXTCODECOPY },
 	{ "RETURNDATASIZE", Instruction::RETURNDATASIZE },
 	{ "RETURNDATACOPY", Instruction::RETURNDATACOPY },
+	{ "EXTCODEHASH", Instruction::EXTCODEHASH },
 	{ "BLOCKHASH", Instruction::BLOCKHASH },
 	{ "COINBASE", Instruction::COINBASE },
 	{ "TIMESTAMP", Instruction::TIMESTAMP },
@@ -216,6 +217,7 @@ static const std::map<Instruction, InstructionInfo> c_instructionInfo =
 	{ 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::EXTCODEHASH,	{ "EXTCODEHASH",	0, 1, 1, false, Tier::ExtCode } },
 	{ 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 } },

libevmasm/Instruction.h

@@ -82,6 +82,7 @@ enum class Instruction: uint8_t
 	EXTCODECOPY,		///< copy external code (from another contract)
 	RETURNDATASIZE = 0x3d,	///< get size of return data buffer
 	RETURNDATACOPY = 0x3e,	///< copy return data in current environment to memory
+	EXTCODEHASH = 0x3f,	///< get external code hash (from another contract)
 
 	BLOCKHASH = 0x40,	///< get hash of most recent complete block
 	COINBASE,			///< get the block's coinbase address

libevmasm/SemanticInformation.cpp

@@ -151,6 +151,7 @@ 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::EXTCODEHASH:
 	case Instruction::RETURNDATACOPY: // depends on previous calls
 	case Instruction::RETURNDATASIZE:
 		return false;
@@ -172,6 +173,7 @@ bool SemanticInformation::movable(Instruction _instruction)
 	case Instruction::KECCAK256:
 	case Instruction::BALANCE:
 	case Instruction::EXTCODESIZE:
+	case Instruction::EXTCODEHASH:
 	case Instruction::RETURNDATASIZE:
 	case Instruction::SLOAD:
 	case Instruction::PC:
@@ -233,6 +235,7 @@ bool SemanticInformation::invalidInPureFunctions(Instruction _instruction)
 	case Instruction::GASPRICE:
 	case Instruction::EXTCODESIZE:
 	case Instruction::EXTCODECOPY:
+	case Instruction::EXTCODEHASH:
 	case Instruction::BLOCKHASH:
 	case Instruction::COINBASE:
 	case Instruction::TIMESTAMP:

libsolidity/inlineasm/AsmAnalysis.cpp

@@ -568,7 +568,17 @@ void AsmAnalyzer::warnOnInstructions(solidity::Instruction _instr, SourceLocatio
 	// Similarly we assume bitwise shifting and create2 go together.
 	solAssert(m_evmVersion.hasBitwiseShifting() == m_evmVersion.hasCreate2(), "");
 
-	if ((
+	if (_instr == solidity::Instruction::EXTCODEHASH)
+		m_errorReporter.warning(
+			_location,
+			"The \"" +
+			boost::to_lower_copy(instructionInfo(_instr).name)
+			+ "\" instruction is not supported by the VM version \"" +
+			"" + m_evmVersion.name() +
+			"\" you are currently compiling for. " +
+			"It will be interpreted as an invalid instruction on this VM."
+		);
+	else if ((
 		_instr == solidity::Instruction::RETURNDATACOPY ||
 		_instr == solidity::Instruction::RETURNDATASIZE ||
 		_instr == solidity::Instruction::STATICCALL