feat(protocol): Gas limit behavior changes (#14339)

Co-authored-by: David <david@taiko.xyz>
Co-authored-by: Daniel Wang <99078276+dantaik@users.noreply.github.com>

packages/protocol/contracts/L1/TaikoData.sol

@@ -52,11 +52,10 @@ library TaikoData {
         uint64 numEthDeposits;
     }
 
-    // 3 slots
+    // 2 slots
     struct BlockMetadataInput {
         bytes32 txListHash;
         address beneficiary;
-        uint32 gasLimit;
         uint24 txListByteStart; // byte-wise start index (inclusive)
         uint24 txListByteEnd; // byte-wise end index (exclusive)
         bool cacheTxListInfo;

packages/protocol/contracts/L1/libs/LibProposing.sol

@@ -103,7 +103,7 @@ library LibProposing {
         meta.txListHash = input.txListHash;
         meta.txListByteStart = input.txListByteStart;
         meta.txListByteEnd = input.txListByteEnd;
-        meta.gasLimit = input.gasLimit;
+        meta.gasLimit = config.blockMaxGasLimit;
         meta.beneficiary = input.beneficiary;
         meta.treasury = resolver.resolve(config.chainId, "treasury", false);
         meta.depositsProcessed =
@@ -183,13 +183,7 @@ library LibProposing {
         view
         returns (bool cacheTxListInfo)
     {
-        if (
-            input.beneficiary == address(0)
-            //
-            || input.gasLimit == 0
-            //
-            || input.gasLimit > config.blockMaxGasLimit
-        ) revert L1_INVALID_METADATA();
+        if (input.beneficiary == address(0)) revert L1_INVALID_METADATA();
 
         if (
             state.numBlocks

packages/protocol/contracts/L2/TaikoL2.sol

@@ -199,12 +199,11 @@ contract TaikoL2 is EssentialContract, TaikoL2Signer, ICrossChainSync {
         uint256 basefee;
         EIP1559Config memory config = getEIP1559Config();
         if (config.gasIssuedPerSecond != 0) {
-            (basefee, gasExcess) = _calcBasefee(
-                config,
-                block.timestamp - parentTimestamp,
-                uint32(block.gaslimit),
-                parentGasUsed
-            );
+            (basefee, gasExcess) = _calcBasefee({
+                config: config,
+                timeSinceParent: block.timestamp - parentTimestamp,
+                parentGasUsed: parentGasUsed
+            });
         }
 
         // On L2, basefee is not burnt, but sent to a treasury instead.
@@ -233,17 +232,18 @@ contract TaikoL2 is EssentialContract, TaikoL2Signer, ICrossChainSync {
     }
 
     function getBasefee(
-        uint32 timeSinceParent,
-        uint32 gasLimit,
+        uint64 timeSinceParent,
         uint32 parentGasUsed
     )
         public
         view
         returns (uint256 _basefee)
     {
-        (_basefee,) = _calcBasefee(
-            getEIP1559Config(), timeSinceParent, gasLimit, parentGasUsed
-        );
+        (_basefee,) = _calcBasefee({
+            config: getEIP1559Config(),
+            timeSinceParent: timeSinceParent,
+            parentGasUsed: parentGasUsed
+        });
     }
 
     function getCrossChainBlockHash(uint256 number)
@@ -321,31 +321,31 @@ contract TaikoL2 is EssentialContract, TaikoL2Signer, ICrossChainSync {
     function _calcBasefee(
         EIP1559Config memory config,
         uint256 timeSinceParent,
-        uint32 gasLimit,
         uint32 parentGasUsed
     )
         private
         view
         returns (uint256 _basefee, uint64 _gasExcess)
     {
-        // Very important to cap _gasExcess uint64
         unchecked {
-            uint32 parentGasUsedNet = parentGasUsed
-                > LibL2Consts.ANCHOR_GAS_COST
-                ? parentGasUsed - LibL2Consts.ANCHOR_GAS_COST
-                : 0;
-
-            uint256 a = uint256(gasExcess) + parentGasUsedNet;
-            uint256 b = config.gasIssuedPerSecond * timeSinceParent;
-            _gasExcess = uint64((a.max(b) - b).min(type(uint64).max));
+            uint32 parentGasUsedNet;
+            if (parentGasUsed > LibL2Consts.ANCHOR_GAS_COST) {
+                parentGasUsedNet = parentGasUsed - LibL2Consts.ANCHOR_GAS_COST;
+            }
+
+            uint256 issued = timeSinceParent * config.gasIssuedPerSecond;
+            uint256 excess = (uint256(gasExcess) + parentGasUsedNet).max(issued);
+            // Very important to cap _gasExcess uint64
+            _gasExcess = uint64((excess - issued).min(type(uint64).max));
         }
 
         _basefee = Lib1559Math.calculatePrice({
             xscale: config.xscale,
             yscale: config.yscale,
             xExcess: _gasExcess,
-            xPurchase: gasLimit
+            xPurchase: 0
         });
+
         if (_basefee == 0) {
             // To make sure when 1559 is enabled, the basefee is non-zero
             // (geth never use 0 values for basefee)

packages/protocol/docs/how_taiko_proves_blocks.md

@@ -25,7 +25,10 @@ A valid transaction (defined in the Ethereum Yellow Paper):
 - Has a valid transaction signature.
 - Has a valid transaction nonce (equivalent to the sender account's current nonce).
 - Has no contract code deployed on the sender account (see EIP-3607 by Feist et al. [2021]).
-- Has a gas limit no smaller than the intrinsic gas, _`g0`_, used by the transaction; and the sender account balance contains at least the cost, _`v0`_, required in up-front payment.
+- Has a gas limit no smaller than the intrinsic gas, _`g0`_, used by the transaction.
+- The sender account balance contains at least the cost, _`v0`_, required in up-front payment.
+- The transaction has a gas limit that is smaller or equal to the amount of gas left in the block (with the block gas limit being the protocol constant _`blockMaxGasLimit`_).
+- The transaction has a basefee that is greater than or equal the basefee of the block.
 
 #### Slicing and Consistency
 

packages/protocol/test/TaikoL1TestBase.t.sol

@@ -168,7 +168,6 @@ abstract contract TaikoL1TestBase is Test {
         bytes memory txList = new bytes(txListSize);
         TaikoData.BlockMetadataInput memory input = TaikoData.BlockMetadataInput({
             beneficiary: proposer,
-            gasLimit: gasLimit,
             txListHash: keccak256(txList),
             txListByteStart: 0,
             txListByteEnd: txListSize,

packages/protocol/test/TaikoL2.t.sol

@@ -39,7 +39,7 @@ contract TestTaikoL2 is Test {
     function testAnchorTxsBlocktimeConstant() external {
         uint256 firstBasefee;
         for (uint256 i = 0; i < 100; i++) {
-            uint256 basefee = _getBasefeeAndPrint(0, BLOCK_GAS_LIMIT);
+            uint256 basefee = _getBasefeeAndPrint2(0, BLOCK_GAS_LIMIT);
             vm.fee(basefee);
 
             if (firstBasefee == 0) {
@@ -60,7 +60,7 @@ contract TestTaikoL2 is Test {
         uint256 prevBasefee;
 
         for (uint256 i = 0; i < 32; i++) {
-            uint256 basefee = _getBasefeeAndPrint(0, BLOCK_GAS_LIMIT);
+            uint256 basefee = _getBasefeeAndPrint2(0, BLOCK_GAS_LIMIT);
             vm.fee(basefee);
 
             assertGe(basefee, prevBasefee);
@@ -78,7 +78,7 @@ contract TestTaikoL2 is Test {
         uint256 prevBasefee;
 
         for (uint256 i = 0; i < 30; i++) {
-            uint256 basefee = _getBasefeeAndPrint(0, BLOCK_GAS_LIMIT);
+            uint256 basefee = _getBasefeeAndPrint2(0, BLOCK_GAS_LIMIT);
             vm.fee(basefee);
 
             if (prevBasefee != 0) {
@@ -97,7 +97,7 @@ contract TestTaikoL2 is Test {
 
     // calling anchor in the same block more than once should fail
     function testAnchorTxsFailInTheSameBlock() external {
-        uint256 expectedBasefee = _getBasefeeAndPrint(0, BLOCK_GAS_LIMIT);
+        uint256 expectedBasefee = _getBasefeeAndPrint2(0, BLOCK_GAS_LIMIT);
         vm.fee(expectedBasefee);
 
         vm.prank(L2.GOLDEN_TOUCH_ADDRESS());
@@ -110,7 +110,7 @@ contract TestTaikoL2 is Test {
 
     // calling anchor in the same block more than once should fail
     function testAnchorTxsFailByNonTaikoL2Signer() external {
-        uint256 expectedBasefee = _getBasefeeAndPrint(0, BLOCK_GAS_LIMIT);
+        uint256 expectedBasefee = _getBasefeeAndPrint2(0, BLOCK_GAS_LIMIT);
         vm.fee(expectedBasefee);
         vm.expectRevert();
         _anchor(BLOCK_GAS_LIMIT);
@@ -133,32 +133,18 @@ contract TestTaikoL2 is Test {
     }
 
     function testGetBasefee() external {
-        uint32 timeSinceParent = uint32(block.timestamp - L2.parentTimestamp());
-        assertEq(_getBasefeeAndPrint(timeSinceParent, 0, 0), 317_609_019);
-        assertEq(_getBasefeeAndPrint(timeSinceParent, 1, 0), 317_609_019);
-        assertEq(
-            _getBasefeeAndPrint(timeSinceParent, 1_000_000, 0), 320_423_332
-        );
-        assertEq(
-            _getBasefeeAndPrint(timeSinceParent, 5_000_000, 0), 332_018_053
-        );
-        assertEq(
-            _getBasefeeAndPrint(timeSinceParent, 10_000_000, 0), 347_305_199
-        );
+        uint64 timeSinceParent = uint64(block.timestamp - L2.parentTimestamp());
+        assertEq(_getBasefeeAndPrint(timeSinceParent, 0), 317_609_019);
 
-        timeSinceParent = uint32(100 + block.timestamp - L2.parentTimestamp());
-        assertEq(_getBasefeeAndPrint(timeSinceParent, 0, 0), 54_544_902);
-        assertEq(_getBasefeeAndPrint(timeSinceParent, 1, 0), 54_544_902);
-        assertEq(_getBasefeeAndPrint(timeSinceParent, 1_000_000, 0), 55_028_221);
-        assertEq(_getBasefeeAndPrint(timeSinceParent, 5_000_000, 0), 57_019_452);
-        assertEq(
-            _getBasefeeAndPrint(timeSinceParent, 10_000_000, 0), 59_644_805
-        );
+        timeSinceParent += 100;
+        assertEq(_getBasefeeAndPrint(timeSinceParent, 0), 54_544_902);
+
+        timeSinceParent += 10_000;
+        assertEq(_getBasefeeAndPrint(timeSinceParent, 0), 1);
     }
 
     function _getBasefeeAndPrint(
-        uint32 timeSinceParent,
-        uint32 gasLimit,
+        uint64 timeSinceParent,
         uint32 parentGasUsed
     )
         private
@@ -175,12 +161,10 @@ contract TestTaikoL2 is Test {
             Strings.toString(timeSinceParent),
             ", gasIssued=",
             Strings.toString(gasIssued),
-            ", gasLimit=",
-            Strings.toString(gasLimit),
             ", parentGasUsed=",
             Strings.toString(parentGasUsed)
         );
-        _basefee = L2.getBasefee(timeSinceParent, gasLimit, parentGasUsed);
+        _basefee = L2.getBasefee(timeSinceParent, parentGasUsed);
         assertTrue(_basefee != 0);
 
         _msg = string.concat(
@@ -194,7 +178,7 @@ contract TestTaikoL2 is Test {
         console2.log(_msg);
     }
 
-    function _getBasefeeAndPrint(
+    function _getBasefeeAndPrint2(
         uint32 timeSinceNow,
         uint32 gasLimit
     )
@@ -203,7 +187,6 @@ contract TestTaikoL2 is Test {
     {
         return _getBasefeeAndPrint(
             uint32(timeSinceNow + block.timestamp - L2.parentTimestamp()),
-            gasLimit,
             gasLimit + ANCHOR_GAS_COST
         );
     }

packages/protocol/test/genesis/GenerateGenesis.g.sol

@@ -34,7 +34,7 @@ contract TestGenerateGenesis is Test, AddressResolver {
     address private owner = configJSON.readAddress(".contractOwner");
     address private admin = configJSON.readAddress(".contractAdmin");
 
-    uint32 public constant BLOCK_GAS_LIMIT = 30_000_000;
+    // uint32 public constant BLOCK_GAS_LIMIT = 30_000_000;
 
     function testContractDeployment() public {
         assertEq(block.chainid, 167);
@@ -107,11 +107,7 @@ contract TestGenerateGenesis is Test, AddressResolver {
         for (uint32 i = 0; i < 300; i++) {
             vm.roll(block.number + 1);
             vm.warp(taikoL2.parentTimestamp() + 12);
-            vm.fee(
-                taikoL2.getBasefee(
-                    12, BLOCK_GAS_LIMIT, i + LibL2Consts.ANCHOR_GAS_COST
-                )
-            );
+            vm.fee(taikoL2.getBasefee(12, i + LibL2Consts.ANCHOR_GAS_COST));
 
             uint256 gasLeftBefore = gasleft();