Merge pull request #4676 from jwasinger/extcodehash

Add support for EXTCODEHASH

9 files changed, 42 insertions, 3 deletions

diff --git a/Changelog.md b/Changelog.md
index 7330f6d3..fbb41ece 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -91,6 +91,7 @@ Compiler Features:
  * Build System: Support for Mojave version of macOS added.
  * 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.
diff --git a/docs/assembly.rst b/docs/assembly.rst
index 5d723645..02a802a8 100644
--- a/docs/assembly.rst
+++ b/docs/assembly.rst
@@ -271,12 +271,14 @@ In the grammar, opcodes are represented as pre-defined identifiers.
 +-------------------------+-----+---+-----------------------------------------------------------------+
 | returndatacopy(t, f, s) | `-` | B | copy s bytes from returndata at position f to mem at position t |
 +-------------------------+-----+---+-----------------------------------------------------------------+
+| extcodehash(a)          |     | C | code hash of address a                                          |
++-------------------------+-----+---+-----------------------------------------------------------------+
 | create(v, p, s)         |     | F | create new contract with code mem[p...(p+s)) and send v wei     |
 |                         |     |   | and return the new address                                      |
 +-------------------------+-----+---+-----------------------------------------------------------------+
 | create2(v, n, p, s)     |     | C | create new contract with code mem[p...(p+s)) at address         |
-|                         |     |   | keccak256(<address> . n . keccak256(mem[p...(p+s))) and send v  |
-|                         |     |   | wei and return the new address                                  |
+|                         |     |   | keccak256(0xff . <address> . n . keccak256(mem[p...(p+s)))      |
+|                         |     |   | and send v wei and return the new address                       |
 +-------------------------+-----+---+-----------------------------------------------------------------+
 | call(g, a, v, in,       |     | F | call contract at address a with input mem[in...(in+insize))     |
 | insize, out, outsize)   |     |   | providing g gas and v wei and output area                       |
diff --git a/libevmasm/GasMeter.cpp b/libevmasm/GasMeter.cpp
index b40617c1..d98b3efa 100644
--- a/libevmasm/GasMeter.cpp
+++ b/libevmasm/GasMeter.cpp
@@ -114,6 +114,9 @@ GasMeter::GasConsumption GasMeter::estimateMax(AssemblyItem const& _item, bool _
 		case Instruction::EXTCODESIZE:
 			gas = GasCosts::extCodeGas(m_evmVersion);
 			break;
+		case Instruction::EXTCODEHASH:
+			gas = GasCosts::balanceGas(m_evmVersion);
+			break;
 		case Instruction::EXTCODECOPY:
 			gas = GasCosts::extCodeGas(m_evmVersion);
 			gas += memoryGas(-1, -3);
diff --git a/libevmasm/Instruction.cpp b/libevmasm/Instruction.cpp
index d5b82e75..cf98c938 100644
--- a/libevmasm/Instruction.cpp
+++ b/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::Balance } },
 	{ 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 50c1f47d..63424eeb 100644
--- a/libevmasm/Instruction.h
+++ b/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
diff --git a/libevmasm/SemanticInformation.cpp b/libevmasm/SemanticInformation.cpp
index 71267ee8..78f3c9c7 100644
--- a/libevmasm/SemanticInformation.cpp
+++ b/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:
diff --git a/libsolidity/inlineasm/AsmAnalysis.cpp b/libsolidity/inlineasm/AsmAnalysis.cpp
index 0f2c0f56..947b6d05 100644
--- a/libsolidity/inlineasm/AsmAnalysis.cpp
+++ b/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
diff --git a/test/liblll/Compiler.cpp b/test/liblll/Compiler.cpp
index be798dc8..a4394f54 100644
--- a/test/liblll/Compiler.cpp
+++ b/test/liblll/Compiler.cpp
@@ -186,6 +186,7 @@ BOOST_AUTO_TEST_CASE(valid_opcodes_functional)
 		"60006000600060003c",
 		"3d",
 		"6000600060003e",
+		"60003f",
 		"600040",
 		"41",
 		"42",
@@ -291,6 +292,7 @@ BOOST_AUTO_TEST_CASE(valid_opcodes_functional)
 		"{ (EXTCODECOPY 0 0 0 0) }",
 		"{ (RETURNDATASIZE) }",
 		"{ (RETURNDATACOPY 0 0 0) }",
+		"{ (EXTCODEHASH 0) }",
 		"{ (BLOCKHASH 0) }",
 		"{ (COINBASE) }",
 		"{ (TIMESTAMP) }",
@@ -409,6 +411,7 @@ BOOST_AUTO_TEST_CASE(valid_opcodes_asm)
 		"3c",
 		"3d",
 		"3e",
+		"3f",
 		"40",
 		"41",
 		"42",
@@ -547,6 +550,7 @@ BOOST_AUTO_TEST_CASE(valid_opcodes_asm)
 		"{ (asm EXTCODECOPY) }",
 		"{ (asm RETURNDATASIZE) }",
 		"{ (asm RETURNDATACOPY) }",
+		"{ (asm EXTCODEHASH) }",
 		"{ (asm BLOCKHASH) }",
 		"{ (asm COINBASE) }",
 		"{ (asm TIMESTAMP) }",
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index b2e2b63b..640bf4d0 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -415,6 +415,19 @@ BOOST_AUTO_TEST_CASE(create2_as_variable)
 	CHECK_ALLOW_MULTI(text, expectations);
 }
 
+BOOST_AUTO_TEST_CASE(extcodehash_as_variable)
+{
+	char const* text = R"(
+		contract c { function f() public view { uint extcodehash; extcodehash; assembly { pop(extcodehash(0)) } }}
+	)";
+	// This needs special treatment, because the message mentions the EVM version,
+	// so cannot be run via isoltest.
+	CHECK_ALLOW_MULTI(text, (std::vector<std::pair<Error::Type, std::string>>{
+		{Error::Type::Warning, "Variable is shadowed in inline assembly by an instruction of the same name"},
+		{Error::Type::Warning, "The \"extcodehash\" instruction is not supported by the VM version"},
+	}));
+}
+
 BOOST_AUTO_TEST_CASE(getter_is_memory_type)
 {
 	char const* text = R"(