Yul builtin for MCOPY

Changelog.md

@@ -5,6 +5,7 @@ Language Features:
  * Introduce global function ``blobhash(uint)`` for retrieving versioned hashes of blobs, akin to the homonymous Yul builtin.
  * Yul: Introduce builtin ``blobbasefee()`` for retrieving the blob base fee of the current block.
  * Yul: Introduce builtin ``blobhash()`` for retrieving versioned hashes of blobs associated with the transaction.
+ * Yul: Introduce builtin ``mcopy()`` for cheaply copying data between memory areas.
 
 Compiler Features:
 * EVM: Support for the EVM Version "Cancun".

docs/grammar/SolidityLexer.g4

@@ -301,7 +301,7 @@ YulEVMBuiltin:
 	| 'pop' | 'mload' | 'mstore' | 'mstore8' | 'sload' | 'sstore' | 'msize' | 'gas'
 	| 'address' | 'balance' | 'selfbalance' | 'caller' | 'callvalue' | 'calldataload'
 	| 'calldatasize' | 'calldatacopy' | 'extcodesize' | 'extcodecopy' | 'returndatasize'
-	| 'returndatacopy' | 'extcodehash' | 'create' | 'create2' | 'call' | 'callcode'
+	| 'returndatacopy' | 'mcopy' | 'extcodehash' | 'create' | 'create2' | 'call' | 'callcode'
 	| 'delegatecall' | 'staticcall' | 'return' | 'revert' | 'selfdestruct' | 'invalid'
 	| 'log0' | 'log1' | 'log2' | 'log3' | 'log4' | 'chainid' | 'origin' | 'gasprice'
 	| 'blockhash' | 'blobhash' | 'coinbase' | 'timestamp' | 'number' | 'difficulty'

docs/using-the-compiler.rst

@@ -179,6 +179,7 @@ at each version. Backward compatibility is not guaranteed between each version.
 - ``cancun``
    - The block's blob base fee (`EIP-7516 <https://eips.ethereum.org/EIPS/eip-7516>`_ and `EIP-4844 <https://eips.ethereum.org/EIPS/eip-4844>`_) can be accessed via the global ``block.blobbasefee`` or ``blobbasefee()`` in inline assembly.
    - Introduces ``blobhash()`` in inline assembly and a corresponding global function to retrieve versioned hashes of blobs associated with the transaction (see `EIP-4844 <https://eips.ethereum.org/EIPS/eip-4844>`_).
+   - Opcode ``mcopy`` is available in assembly (see `EIP-5656 <https://eips.ethereum.org/EIPS/eip-5656>`_).
 
 .. index:: ! standard JSON, ! --standard-json
 .. _compiler-api:

docs/yul.rst

@@ -865,6 +865,8 @@ the ``dup`` and ``swap`` instructions as well as ``jump`` instructions, labels a
 +-------------------------+-----+---+-----------------------------------------------------------------+
 | returndatacopy(t, f, s) | `-` | B | copy s bytes from returndata at position f to mem at position t |
 +-------------------------+-----+---+-----------------------------------------------------------------+
+| mcopy(t, f, s)          | `-` | N | copy s bytes from mem at position f to mem at position t        |
++-------------------------+-----+---+-----------------------------------------------------------------+
 | extcodehash(a)          |     | C | code hash of address a                                          |
 +-------------------------+-----+---+-----------------------------------------------------------------+
 | create(v, p, n)         |     | F | create new contract with code mem[p...(p+n)) and send v wei     |

libevmasm/GasMeter.cpp

@@ -115,6 +115,16 @@ GasMeter::GasConsumption GasMeter::estimateMax(AssemblyItem const& _item, bool _
 			gas += memoryGas(0, -2);
 			gas += wordGas(GasCosts::copyGas, m_state->relativeStackElement(-2));
 			break;
+		case Instruction::MCOPY:
+		{
+			GasConsumption memoryGasFromRead = memoryGas(-1, -2);
+			GasConsumption memoryGasFromWrite = memoryGas(0, -2);
+
+			gas = runGas(_item.instruction(), m_evmVersion);
+			gas += (memoryGasFromRead < memoryGasFromWrite ? memoryGasFromWrite : memoryGasFromRead);
+			gas += wordGas(GasCosts::copyGas, m_state->relativeStackElement(-2));
+			break;
+		}
 		case Instruction::EXTCODESIZE:
 			gas = GasCosts::extCodeGas(m_evmVersion);
 			break;

libevmasm/Instruction.cpp

@@ -70,6 +70,7 @@ std::map<std::string, Instruction> const solidity::evmasm::c_instructions =
 	{ "EXTCODECOPY", Instruction::EXTCODECOPY },
 	{ "RETURNDATASIZE", Instruction::RETURNDATASIZE },
 	{ "RETURNDATACOPY", Instruction::RETURNDATACOPY },
+	{ "MCOPY", Instruction::MCOPY },
 	{ "EXTCODEHASH", Instruction::EXTCODEHASH },
 	{ "BLOCKHASH", Instruction::BLOCKHASH },
 	{ "BLOBHASH", Instruction::BLOBHASH },
@@ -222,6 +223,7 @@ static std::map<Instruction, InstructionInfo> const 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::MCOPY,       { "MCOPY",          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::BLOBHASH,    { "BLOBHASH",       0, 1, 1, false, Tier::VeryLow } },

libevmasm/Instruction.h

@@ -104,6 +104,7 @@ enum class Instruction: uint8_t
 	MSIZE,				///< get the size of active memory
 	GAS,				///< get the amount of available gas
 	JUMPDEST,			///< set a potential jump destination
+	MCOPY = 0x5e,       ///< copy between memory areas
 
 	PUSH0 = 0x5f,       ///< place the value 0 on stack
 	PUSH1 = 0x60,		///< place 1 byte item on stack

libevmasm/SemanticInformation.cpp

@@ -104,6 +104,25 @@ std::vector<SemanticInformation::Operation> SemanticInformation::readWriteOperat
 		op.lengthParameter = 2;
 		return {op};
 	}
+	case Instruction::MCOPY:
+	{
+		assertThrow(memory(_instruction) != Effect::None, OptimizerException, "");
+		assertThrow(storage(_instruction) == Effect::None, OptimizerException, "");
+
+		Operation readOperation;
+		readOperation.effect = Read;
+		readOperation.location = Location::Memory;
+		readOperation.startParameter = 1;
+		readOperation.lengthParameter = 2;
+
+		Operation writeOperation;
+		writeOperation.effect = Write;
+		writeOperation.location = Location::Memory;
+		writeOperation.startParameter = 0;
+		writeOperation.lengthParameter = 2;
+
+		return {readOperation, writeOperation};
+	}
 	case Instruction::STATICCALL:
 	case Instruction::CALL:
 	case Instruction::CALLCODE:
@@ -188,7 +207,7 @@ bool SemanticInformation::breaksCSEAnalysisBlock(AssemblyItem const& _item, bool
 		))
 			return false;
 		//@todo: We do not handle the following memory instructions for now:
-		// calldatacopy, codecopy, extcodecopy, mstore8,
+		// calldatacopy, codecopy, extcodecopy, mcopy, mstore8,
 		// msize (note that msize also depends on memory read access)
 
 		// the second requirement will be lifted once it is implemented
@@ -363,6 +382,7 @@ SemanticInformation::Effect SemanticInformation::memory(Instruction _instruction
 	case Instruction::CODECOPY:
 	case Instruction::EXTCODECOPY:
 	case Instruction::RETURNDATACOPY:
+	case Instruction::MCOPY:
 	case Instruction::MSTORE:
 	case Instruction::MSTORE8:
 	case Instruction::CALL:

libevmasm/SimplificationRule.h

@@ -117,6 +117,7 @@ struct EVMBuiltins
 	static auto constexpr EXTCODECOPY = PatternGenerator<Instruction::EXTCODECOPY>{};
 	static auto constexpr RETURNDATASIZE = PatternGenerator<Instruction::RETURNDATASIZE>{};
 	static auto constexpr RETURNDATACOPY = PatternGenerator<Instruction::RETURNDATACOPY>{};
+	static auto constexpr MCOPY = PatternGenerator<Instruction::MCOPY>{};
 	static auto constexpr EXTCODEHASH = PatternGenerator<Instruction::EXTCODEHASH>{};
 	static auto constexpr BLOCKHASH = PatternGenerator<Instruction::BLOCKHASH>{};
 	static auto constexpr BLOBHASH = PatternGenerator<Instruction::BLOBHASH>{};

liblangutil/EVMVersion.cpp

@@ -53,6 +53,8 @@ bool EVMVersion::hasOpcode(Instruction _opcode) const
 		return hasBlobHash();
 	case Instruction::BLOBBASEFEE:
 		return hasBlobBaseFee();
+	case Instruction::MCOPY:
+		return hasMcopy();
 	default:
 		return true;
 	}

liblangutil/EVMVersion.h

@@ -105,6 +105,7 @@ class EVMVersion:
 	bool hasPrevRandao() const { return *this >= paris(); }
 	bool hasPush0() const { return *this >= shanghai(); }
 	bool hasBlobHash() const { return *this >= cancun(); }
+	bool hasMcopy() const { return *this >= cancun(); }
 
 	bool hasOpcode(evmasm::Instruction _opcode) const;
 

libyul/AsmAnalysis.cpp

@@ -736,6 +736,9 @@ bool AsmAnalyzer::validateInstructions(evmasm::Instruction _instr, SourceLocatio
 	else if (_instr == evmasm::Instruction::BLOBHASH && !m_evmVersion.hasBlobHash())
 		// TODO: Change this assertion to an error, similar to the ones above, when Cancun becomes the default EVM version.
 		yulAssert(false);
+	else if (_instr == evmasm::Instruction::MCOPY && !m_evmVersion.hasMcopy())
+		// TODO: Change this assertion to an error, similar to the ones above, when Cancun becomes the default EVM version.
+		yulAssert(false);
 	else if (_instr == evmasm::Instruction::PC)
 		m_errorReporter.error(
 			2450_error,

libyul/backends/evm/EVMDialect.cpp

@@ -127,6 +127,13 @@ std::set<YulString> createReservedIdentifiers(langutil::EVMVersion _evmVersion)
 		return _instr == evmasm::Instruction::BLOBBASEFEE && _evmVersion < langutil::EVMVersion::cancun();
 	};
 
+	// TODO remove this in 0.9.0. We allow creating functions or identifiers in Yul with the name
+	// mcopy for VMs before london.
+	auto mcopyException = [&](evmasm::Instruction _instr) -> bool
+	{
+		return _instr == evmasm::Instruction::MCOPY && _evmVersion < langutil::EVMVersion::cancun();
+	};
+
 	// TODO remove this in 0.9.0. We allow creating functions or identifiers in Yul with the name
 	// prevrandao for VMs before paris.
 	auto prevRandaoException = [&](std::string const& _instrName) -> bool
@@ -150,7 +157,8 @@ std::set<YulString> createReservedIdentifiers(langutil::EVMVersion _evmVersion)
 			!baseFeeException(instr.second) &&
 			!prevRandaoException(name) &&
 			!blobHashException(instr.second) &&
-			!blobBaseFeeException(instr.second)
+			!blobBaseFeeException(instr.second) &&
+			!mcopyException(instr.second)
 		)
 			reserved.emplace(name);
 	}

libyul/optimiser/UnusedStoreEliminator.cpp

@@ -172,9 +172,12 @@ void UnusedStoreEliminator::visit(Statement const& _statement)
 		*instruction == Instruction::CODECOPY ||
 		*instruction == Instruction::CALLDATACOPY ||
 		*instruction == Instruction::RETURNDATACOPY ||
+		// TODO: Removing MCOPY is complicated because it's not just a store but also a load.
+		//*instruction == Instruction::MCOPY ||
 		*instruction == Instruction::MSTORE ||
 		*instruction == Instruction::MSTORE8;
 	bool isCandidateForRemoval =
+		*instruction != Instruction::MCOPY &&
 		SemanticInformation::otherState(*instruction) != SemanticInformation::Write && (
 			SemanticInformation::storage(*instruction) == SemanticInformation::Write ||
 			(!m_ignoreMemory && SemanticInformation::memory(*instruction) == SemanticInformation::Write)

scripts/test_antlr_grammar.sh

@@ -123,6 +123,8 @@ done < <(
       grep -v -E 'inlineAssembly/basefee_berlin_function.sol' |
       # Skipping a test with "let blobbasefee := ..."
       grep -v -E 'inlineAssembly/blobbasefee_shanghai_function.sol' |
+      # Skipping a test with "let mcopy := ..."
+      grep -v -E 'inlineAssembly/mcopy_as_identifier_pre_cancun.sol' |
       # Skipping tests with "let prevrandao := ..."
       grep -v -E 'inlineAssembly/prevrandao_allowed_function_pre_paris.sol' |
       grep -v -E 'inlineAssembly/prevrandao_disallowed_function_post_paris.sol' |

test/libsolidity/GasMeter.cpp

@@ -32,6 +32,7 @@ using namespace solidity::langutil;
 using namespace solidity::evmasm;
 using namespace solidity::frontend;
 using namespace solidity::frontend::test;
+using namespace solidity::test;
 
 namespace solidity::frontend::test
 {
@@ -339,6 +340,113 @@ BOOST_AUTO_TEST_CASE(complex_control_flow)
 	testRunTimeGas("ln(int128)", std::vector<bytes>{encodeArgs(0), encodeArgs(10), encodeArgs(105), encodeArgs(30000)});
 }
 
+BOOST_AUTO_TEST_CASE(
+	mcopy_memory_expansion_gas,
+	*boost::unit_test::precondition(minEVMVersionCheck(EVMVersion::cancun()))
+)
+{
+	char const* sourceCode = R"(
+		contract C {
+			function no_expansion() public {
+				assembly {
+					mstore(0xffe0, 1) // expand memory before using mcopy
+					mcopy(0, 0xffff, 1)
+					return(0, 1)
+				}
+			}
+
+			function expansion_on_write() public {
+				assembly {
+					mcopy(0xffff, 0, 1)
+					return(0xffff, 1)
+				}
+			}
+
+			function expansion_on_read() public {
+				assembly {
+					mcopy(0, 0xffff, 1)
+					return(0, 1)
+				}
+			}
+
+			function expansion_on_read_write() public {
+				assembly {
+					mcopy(0xffff, 0xffff, 1)
+					return(0, 1)
+				}
+			}
+
+			function expansion_on_zero_size() public {
+				assembly {
+					mcopy(0xffff, 0xffff, 0)
+					return(0, 1)
+				}
+			}
+
+			function expansion_on_0_0_0() public {
+				assembly {
+					mcopy(0, 0, 0)
+					return(0, 1)
+				}
+			}
+		}
+	)";
+	testCreationTimeGas(sourceCode);
+	testRunTimeGas("no_expansion()", {encodeArgs()});
+	testRunTimeGas("expansion_on_write()", {encodeArgs()});
+	testRunTimeGas("expansion_on_read()", {encodeArgs()});
+	testRunTimeGas("expansion_on_read_write()", {encodeArgs()});
+	testRunTimeGas("expansion_on_zero_size()", {encodeArgs()});
+	testRunTimeGas("expansion_on_0_0_0()", {encodeArgs()});
+}
+
+BOOST_AUTO_TEST_CASE(
+	mcopy_word_gas,
+	*boost::unit_test::precondition(minEVMVersionCheck(EVMVersion::cancun()))
+)
+{
+	char const* sourceCode = R"(
+		contract C {
+			function no_overlap() public {
+				assembly {
+					mstore(0xffe0, 1) // expand memory before using mcopy
+					mcopy(0x4000, 0x2000, 0x2000)
+					return(0, 0x10000)
+				}
+			}
+
+			function overlap_right() public {
+				assembly {
+					mstore(0xffe0, 1) // expand memory before using mcopy
+					mcopy(0x3000, 0x2000, 0x2000)
+					return(0, 0x10000)
+				}
+			}
+
+			function overlap_left() public {
+				assembly {
+					mstore(0xffe0, 1) // expand memory before using mcopy
+					mcopy(0x1000, 0x2000, 0x2000)
+					return(0, 0x10000)
+				}
+			}
+
+			function overlap_full() public {
+				assembly {
+					mstore(0xffe0, 1) // expand memory before using mcopy
+					mcopy(0x2000, 0x2000, 0x2000)
+					return(0, 0x10000)
+				}
+			}
+		}
+	)";
+	testCreationTimeGas(sourceCode);
+	testRunTimeGas("no_overlap()", {encodeArgs()});
+	testRunTimeGas("overlap_right()", {encodeArgs()});
+	testRunTimeGas("overlap_left()", {encodeArgs()});
+	testRunTimeGas("overlap_full()", {encodeArgs()});
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }

test/libsolidity/memoryGuardTests/marked_empty.sol

@@ -0,0 +1,12 @@
+contract C {
+    constructor() {
+        assembly ("memory-safe") {}
+    }
+
+    function f() public {
+        assembly ("memory-safe") {}
+    }
+}
+// ----
+// :C(creation) true
+// :C(runtime) true

test/libsolidity/memoryGuardTests/marked_with_memory_access.sol

@@ -0,0 +1,16 @@
+contract C {
+    constructor() {
+        assembly ("memory-safe") {
+            mstore(0, 1)
+        }
+    }
+
+    function store() public {
+        assembly ("memory-safe") {
+            mstore(0, 1)
+        }
+    }
+}
+// ----
+// :C(creation) true
+// :C(runtime) true

test/libsolidity/memoryGuardTests/unmarked_empty.sol

@@ -0,0 +1,12 @@
+contract C {
+    constructor() {
+        assembly {}
+    }
+
+    function f() public {
+        assembly {}
+    }
+}
+// ----
+// :C(creation) true
+// :C(runtime) true

test/libsolidity/memoryGuardTests/unmarked_with_memory_access_mcopy.sol

@@ -0,0 +1,18 @@
+contract C {
+    constructor() {
+        assembly {
+            mcopy(1000, 2000, 1000)
+        }
+    }
+
+    function copy() public {
+        assembly {
+            mcopy(1000, 2000, 1000)
+        }
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// :C(creation) false
+// :C(runtime) false