EIP 4844 - blobhash opcode (part 1)

Changelog.md

@@ -3,7 +3,7 @@
 Language Features:
  * Introduce global ``block.blobbasefee`` for retrieving the blob base fee of the current block.
  * 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.
 
 Compiler Features:
  * EVM: Support for the EVM Version "Cancun".

docs/grammar/SolidityLexer.g4

@@ -304,8 +304,8 @@ YulEVMBuiltin:
 	| 'returndatacopy' | 'extcodehash' | 'create' | 'create2' | 'call' | 'callcode'
 	| 'delegatecall' | 'staticcall' | 'return' | 'revert' | 'selfdestruct' | 'invalid'
 	| 'log0' | 'log1' | 'log2' | 'log3' | 'log4' | 'chainid' | 'origin' | 'gasprice'
-	| 'blockhash' | 'coinbase' | 'timestamp' | 'number' | 'difficulty' | 'prevrandao'
-	| 'gaslimit' | 'basefee' | 'blobbasefee';
+	| 'blockhash' | 'blobhash' | 'coinbase' | 'timestamp' | 'number' | 'difficulty'
+	| 'prevrandao' | 'gaslimit' | 'basefee' | 'blobbasefee';
 
 YulLBrace: '{' -> pushMode(YulMode);
 YulRBrace: '}' -> popMode;

docs/yul.rst

@@ -927,6 +927,8 @@ the ``dup`` and ``swap`` instructions as well as ``jump`` instructions, labels a
 +-------------------------+-----+---+-----------------------------------------------------------------+
 | blockhash(b)            |     | F | hash of block nr b - only for last 256 blocks excluding current |
 +-------------------------+-----+---+-----------------------------------------------------------------+
+| blobhash(i)             |     | N | versioned hash of transaction's i-th blob                       |
++-------------------------+-----+---+-----------------------------------------------------------------+
 | coinbase()              |     | F | current mining beneficiary                                      |
 +-------------------------+-----+---+-----------------------------------------------------------------+
 | timestamp()             |     | F | timestamp of the current block in seconds since the epoch       |

libevmasm/Instruction.cpp

@@ -72,6 +72,7 @@ std::map<std::string, Instruction> const solidity::evmasm::c_instructions =
 	{ "RETURNDATACOPY", Instruction::RETURNDATACOPY },
 	{ "EXTCODEHASH", Instruction::EXTCODEHASH },
 	{ "BLOCKHASH", Instruction::BLOCKHASH },
+	{ "BLOBHASH", Instruction::BLOBHASH },
 	{ "COINBASE", Instruction::COINBASE },
 	{ "TIMESTAMP", Instruction::TIMESTAMP },
 	{ "NUMBER", Instruction::NUMBER },
@@ -223,6 +224,7 @@ static std::map<Instruction, InstructionInfo> const c_instructionInfo =
 	{ 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::BLOBHASH,    { "BLOBHASH",       0, 1, 1, false, Tier::VeryLow } },
 	{ Instruction::COINBASE,	{ "COINBASE",		0, 0, 1, false, Tier::Base } },
 	{ Instruction::TIMESTAMP,	{ "TIMESTAMP",		0, 0, 1, false, Tier::Base } },
 	{ Instruction::NUMBER,		{ "NUMBER",			0, 0, 1, false, Tier::Base } },

libevmasm/Instruction.h

@@ -89,6 +89,7 @@ enum class Instruction: uint8_t
 	CHAINID,			///< get the config's chainid param
 	SELFBALANCE,		///< get balance of the current account
 	BASEFEE,            ///< get the block's basefee
+	BLOBHASH = 0x49,    ///< get a versioned hash of one of the blobs associated with the transaction
 	BLOBBASEFEE = 0x4a, ///< get the block's blob basefee
 
 	POP = 0x50,			///< remove item from stack

libevmasm/SemanticInformation.cpp

@@ -480,6 +480,7 @@ bool SemanticInformation::invalidInPureFunctions(Instruction _instruction)
 	case Instruction::EXTCODECOPY:
 	case Instruction::EXTCODEHASH:
 	case Instruction::BLOCKHASH:
+	case Instruction::BLOBHASH:
 	case Instruction::COINBASE:
 	case Instruction::TIMESTAMP:
 	case Instruction::NUMBER:

libevmasm/SimplificationRule.h

@@ -119,6 +119,7 @@ struct EVMBuiltins
 	static auto constexpr RETURNDATACOPY = PatternGenerator<Instruction::RETURNDATACOPY>{};
 	static auto constexpr EXTCODEHASH = PatternGenerator<Instruction::EXTCODEHASH>{};
 	static auto constexpr BLOCKHASH = PatternGenerator<Instruction::BLOCKHASH>{};
+	static auto constexpr BLOBHASH = PatternGenerator<Instruction::BLOBHASH>{};
 	static auto constexpr COINBASE = PatternGenerator<Instruction::COINBASE>{};
 	static auto constexpr TIMESTAMP = PatternGenerator<Instruction::TIMESTAMP>{};
 	static auto constexpr NUMBER = PatternGenerator<Instruction::NUMBER>{};

liblangutil/EVMVersion.cpp

@@ -49,6 +49,8 @@ bool EVMVersion::hasOpcode(Instruction _opcode) const
 		return hasSelfBalance();
 	case Instruction::BASEFEE:
 		return hasBaseFee();
+	case Instruction::BLOBHASH:
+		return hasBlobHash();
 	case Instruction::BLOBBASEFEE:
 		return hasBlobBaseFee();
 	default:

liblangutil/EVMVersion.h

@@ -104,6 +104,7 @@ class EVMVersion:
 	bool hasBlobBaseFee() const { return *this >= cancun(); }
 	bool hasPrevRandao() const { return *this >= paris(); }
 	bool hasPush0() const { return *this >= shanghai(); }
+	bool hasBlobHash() const { return *this >= cancun(); }
 
 	bool hasOpcode(evmasm::Instruction _opcode) const;
 

libyul/AsmAnalysis.cpp

@@ -670,6 +670,7 @@ void AsmAnalyzer::expectType(YulString _expectedType, YulString _givenType, Sour
 
 bool AsmAnalyzer::validateInstructions(std::string const& _instructionIdentifier, langutil::SourceLocation const& _location)
 {
+	// NOTE: This function uses the default EVM version instead of the currently selected one.
 	auto const builtin = EVMDialect::strictAssemblyForEVM(EVMVersion{}).builtin(YulString(_instructionIdentifier));
 	if (builtin && builtin->instruction.has_value())
 		return validateInstructions(builtin->instruction.value(), _location);
@@ -705,6 +706,9 @@ bool AsmAnalyzer::validateInstructions(evmasm::Instruction _instr, SourceLocatio
 		);
 	};
 
+	// The errors below are meant to be issued when processing an undeclared identifier matching a builtin name
+	// present on the default EVM version but not on the currently selected one,
+	// since the other `validateInstructions()` overload uses the default EVM version.
 	if (_instr == evmasm::Instruction::RETURNDATACOPY && !m_evmVersion.supportsReturndata())
 		errorForVM(7756_error, "only available for Byzantium-compatible");
 	else if (_instr == evmasm::Instruction::RETURNDATASIZE && !m_evmVersion.supportsReturndata())
@@ -729,6 +733,9 @@ bool AsmAnalyzer::validateInstructions(evmasm::Instruction _instr, SourceLocatio
 		errorForVM(5430_error, "only available for London-compatible");
 	else if (_instr == evmasm::Instruction::BLOBBASEFEE && !m_evmVersion.hasBlobBaseFee())
 		errorForVM(6679_error, "only available for Cancun-compatible");
+	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::PC)
 		m_errorReporter.error(
 			2450_error,

libyul/backends/evm/EVMDialect.cpp

@@ -135,14 +135,22 @@ std::set<YulString> createReservedIdentifiers(langutil::EVMVersion _evmVersion)
 		return _instrName == "prevrandao" && _evmVersion < langutil::EVMVersion::paris();
 	};
 
+	// TODO remove this in 0.9.0. We allow creating functions or identifiers in Yul with the name
+	// blobhash for VMs before cancun.
+	auto blobHashException = [&](evmasm::Instruction _instr) -> bool
+	{
+		return _instr == evmasm::Instruction::BLOBHASH && _evmVersion < langutil::EVMVersion::cancun();
+	};
+
 	std::set<YulString> reserved;
 	for (auto const& instr: evmasm::c_instructions)
 	{
 		std::string name = toLower(instr.first);
 		if (
 			!baseFeeException(instr.second) &&
-			!blobBaseFeeException(instr.second) &&
-			!prevRandaoException(name)
+			!prevRandaoException(name) &&
+			!blobHashException(instr.second) &&
+			!blobBaseFeeException(instr.second)
 		)
 			reserved.emplace(name);
 	}

scripts/test_antlr_grammar.sh

@@ -126,6 +126,8 @@ done < <(
       # 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' |
+      # Skipping a test with "let blobhash := ..."
+      grep -v -E 'inlineAssembly/blobhash_pre_cancun.sol' |
       # Skipping license error, unrelated to the grammar
       grep -v -E 'license/license_double5.sol' |
       grep -v -E 'license/license_hidden_unicode.sol' |

test/EVMHost.cpp

@@ -139,6 +139,13 @@ EVMHost::EVMHost(langutil::EVMVersion _evmVersion, evmc::VM& _vm):
 	// The minimum value of blobbasefee
 	tx_context.blob_base_fee = evmc::bytes32{1};
 
+	static evmc_bytes32 const blob_hashes_array[] = {
+		0x0100000000000000000000000000000000000000000000000000000000000001_bytes32,
+		0x0100000000000000000000000000000000000000000000000000000000000002_bytes32
+	};
+	tx_context.blob_hashes = blob_hashes_array;
+	tx_context.blob_hashes_count = sizeof(blob_hashes_array) / sizeof(blob_hashes_array[0]);
+
 	// Reserve space for recording calls.
 	if (!recorded_calls.capacity())
 		recorded_calls.reserve(max_recorded_calls);

test/libsolidity/semanticTests/inlineAssembly/blobhash.sol

@@ -0,0 +1,11 @@
+contract C {
+    function f() public view returns (bytes32 ret) {
+        assembly {
+            ret := blobhash(0)
+        }
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// f() -> 0x0100000000000000000000000000000000000000000000000000000000000001

test/libsolidity/semanticTests/inlineAssembly/blobhash_index_exceeding_blob_count.sol

@@ -0,0 +1,14 @@
+contract C {
+    function f() public view returns (bytes32 ret) {
+        assembly {
+            // EIP-4844 specifies that if `index < len(tx.blob_versioned_hashes)`, `blobhash(index)` should return 0.
+            // Thus, as we injected only two blob hashes in the transaction context in EVMHost,
+            // the return value of the function below MUST be zero.
+            ret := blobhash(2)
+        }
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// f() -> 0x00

test/libsolidity/semanticTests/inlineAssembly/blobhash_pre_cancun.sol

@@ -0,0 +1,21 @@
+contract C {
+    function f() public pure returns (uint ret) {
+        assembly {
+            let blobhash := 1
+            ret := blobhash
+        }
+    }
+    function g() public pure returns (uint ret) {
+        assembly {
+            function blobhash() -> r {
+                r := 1000
+            }
+            ret := blobhash()
+        }
+    }
+}
+// ====
+// EVMVersion: <=shanghai
+// ----
+// f() -> 1
+// g() -> 1000

test/libsolidity/syntaxTests/inlineAssembly/blobhash.sol

@@ -0,0 +1,10 @@
+contract C {
+    function f() public view returns (bytes32 ret) {
+        assembly {
+            ret := blobhash(1)
+        }
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----

test/libsolidity/syntaxTests/inlineAssembly/blobhash_pre_cancun.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f() pure external returns (bytes32 ret) {
+        assembly {
+            ret := blobhash()
+        }
+    }
+}
+// ====
+// EVMVersion: <=shanghai
+// ----
+// DeclarationError 4619: (106-114): Function "blobhash" not found.
+// DeclarationError 8678: (99-116): Variable count for assignment to "ret" does not match number of values (1 vs. 0)

test/libsolidity/syntaxTests/inlineAssembly/blobhash_reserved_cancun.sol

@@ -0,0 +1,14 @@
+contract C {
+    function f() public pure returns (uint ret) {
+        assembly {
+            function blobhash() -> r {
+                r := 1000
+            }
+            ret := blobhash()
+        }
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// ParserError 5568: (103-111): Cannot use builtin function name "blobhash" as identifier name.

test/libsolidity/syntaxTests/viewPureChecker/blobhash_not_pure.sol

@@ -0,0 +1,9 @@
+contract C {
+    function f() public pure {
+        assembly { pop(blobhash(0)) }
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// TypeError 2527: (67-78): Function declared as pure, but this expression (potentially) reads from the environment or state and thus requires "view".

test/libsolidity/syntaxTests/viewPureChecker/inline_assembly_instructions_allowed_view_cancun.sol

@@ -1,6 +1,7 @@
 contract C {
     function f() public view {
         assembly {
+            pop(blobhash(0))
             pop(blobbasefee())
         }
     }

test/libsolidity/syntaxTests/viewPureChecker/inline_assembly_instructions_disallowed_pure_cancun.sol

@@ -1,11 +1,13 @@
 contract C {
     function f() public pure {
         assembly {
+            pop(blobhash(0))
             pop(blobbasefee())
         }
     }
 }
 // ====
 // EVMVersion: >=cancun
 // ----
-// TypeError 2527: (79-92): Function declared as pure, but this expression (potentially) reads from the environment or state and thus requires "view".
+// TypeError 2527: (79-90): Function declared as pure, but this expression (potentially) reads from the environment or state and thus requires "view".
+// TypeError 2527: (108-121): Function declared as pure, but this expression (potentially) reads from the environment or state and thus requires "view".

test/libyul/yulInterpreterTests/blobhash.yul

@@ -0,0 +1,13 @@
+{
+    sstore(0, blobhash(0))
+    sstore(1, blobhash(1))
+    sstore(2, blobhash(2)) // should store 0 since EVMHost has only two blob hashes injected in the block the transaction is being executed.
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// Trace:
+// Memory dump:
+// Storage dump:
+//   0000000000000000000000000000000000000000000000000000000000000000: 014916dd28fc4c10d78e287ca5d9cc51ee1ae73cbfde08c6b37324cbfaac8bc5
+//   0000000000000000000000000000000000000000000000000000000000000001: 0167d3dbed802941483f1afa2a6bc68de5f653128aca9bf1461c5d0a3ad36ed2

test/libyul/yulSyntaxTests/blobhash.yul

@@ -0,0 +1,15 @@
+{
+    {
+        let blobhash := 1
+    }
+
+    {
+        function blobhash() {}
+        blobhash()
+    }
+}
+
+// ====
+// EVMVersion: >=cancun
+// ----
+// ParserError 5568: (20-28): Cannot use builtin function name "blobhash" as identifier name.

test/libyul/yulSyntaxTests/blobhash_pre_cancun.yul

@@ -0,0 +1,13 @@
+{
+    {
+        let blobhash := 1
+    }
+
+    {
+        function blobhash() {}
+        blobhash()
+    }
+}
+// ====
+// EVMVersion: <=shanghai
+// ----

test/tools/yulInterpreter/EVMInstructionInterpreter.cpp

@@ -31,6 +31,7 @@
 
 #include <libsolutil/Keccak256.h>
 #include <libsolutil/Numeric.h>
+#include <libsolutil/picosha2.h>
 
 #include <limits>
 
@@ -233,6 +234,8 @@ u256 EVMInstructionInterpreter::eval(
 		return m_state.chainid;
 	case Instruction::BASEFEE:
 		return m_state.basefee;
+	case Instruction::BLOBHASH:
+		return blobHash(arg[0]);
 	case Instruction::BLOBBASEFEE:
 		return m_state.blobbasefee;
 	case Instruction::EXTCODESIZE:
@@ -649,3 +652,16 @@ std::pair<bool, size_t> EVMInstructionInterpreter::isInputMemoryPtrModified(
 	else
 		return {false, 0};
 }
+
+h256 EVMInstructionInterpreter::blobHash(u256 const& _index)
+{
+	yulAssert(m_evmVersion.hasBlobHash());
+	if (_index >= m_state.blobCommitments.size())
+		return util::FixedHash<32>{};
+
+	h256 hashedCommitment = h256(picosha2::hash256(toBigEndian(m_state.blobCommitments[static_cast<size_t>(_index)])));
+	yulAssert(m_state.blobHashVersion.size == 1);
+	hashedCommitment[0] = *m_state.blobHashVersion.data();
+	yulAssert(hashedCommitment.size == 32);
+	return hashedCommitment;
+}

test/tools/yulInterpreter/EVMInstructionInterpreter.h

@@ -24,6 +24,7 @@
 #include <libyul/ASTForward.h>
 
 #include <libsolutil/CommonData.h>
+#include <libsolutil/FixedHash.h>
 #include <libsolutil/Numeric.h>
 
 #include <liblangutil/EVMVersion.h>
@@ -90,6 +91,9 @@ class EVMInstructionInterpreter
 		std::vector<u256> const& _evaluatedArguments
 	);
 
+	/// @returns the blob versioned hash
+	util::h256 blobHash(u256 const& _index);
+
 private:
 	/// Checks if the memory access is valid and adjusts msize accordingly.
 	/// @returns true if memory access is valid, false otherwise

test/tools/yulInterpreter/Interpreter.h

@@ -113,6 +113,11 @@ struct InterpreterState
 	/// Number of the current state instance, used for recursion protection
 	size_t numInstance = 0;
 
+	// Blob commitment hash version
+	util::FixedHash<1> const blobHashVersion = util::FixedHash<1>(1);
+	// Blob commitments
+	std::array<u256, 2> const blobCommitments = {0x01, 0x02};
+
 	/// Prints execution trace and non-zero storage to @param _out.
 	/// Flag @param _disableMemoryTrace, if set, does not produce a memory dump. This
 	/// avoids false positives reports by the fuzzer when certain optimizer steps are