Implement VIPs for MakerPSM -- PRO-115 #46
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@dekz now that you're back, what do you think of removing the |
| | Settler | 0x V4 | USDC/WETH | 174977 | 55.14% | | ||
| | Settler | 0x V4 | USDC/WETH | 202822 | 79.83% | | ||
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| | 0x V4 | 0x V4 | DAI/WETH | 93311 | 0.00% | | ||
| | Settler | Settler | DAI/WETH | 94258 | 1.01% | | ||
| | Settler | 0x V4 | DAI/WETH | 145780 | 56.23% | | ||
| | Settler | 0x V4 | DAI/WETH | 172912 | 85.31% | | ||
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| | 0x V4 | 0x V4 | USDT/WETH | 104423 | 0.00% | | ||
| | Settler | Settler | USDT/WETH | 105370 | 0.91% | | ||
| | Settler | 0x V4 | USDT/WETH | 160683 | 53.88% | | ||
| | Settler | 0x V4 | USDT/WETH | 188244 | 80.27% | |
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previous versions of this comparison weren't accurate because they failed to actually transfer the buy token to the taker. this PR rectifies that oversight in the unit test, massively increasing the gas consumed
| let swapCalldata := ptr | ||
| let swapCalldata := add(ptr, 0x1c) |
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A lot of the golfing going on here concerns left-padding (right-aligning) constants instead of right-padding (left-aligning) them. We're able to do that without pessimizing gas consumption and it makes the contract significantly smaller.
| let path := add(encodedPath, 0x20) | ||
| let end := add(add(encodedPath, mload(encodedPath)), 0x0c) |
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This is the only place where gas is pessimized in this changeset. This incurs a small gas penalty for UniV2 single-hop with the benefit of significantly reducing gas consumption for multi-hop
| } | ||
| default { revert(0, 0) } | ||
| let toPool := keccak256(ptr, 85) | ||
| let toPool := and(0xffffffffffffffffffffffffffffffffffffffff, keccak256(add(ptr, 0x0b), 0x55)) |
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We do have to clean this variable for multihop because we store it in memory and to form the calldata for the call to swap(...) or transfer(...). It's probably worth checking both Vyper and Solidity's behavior when there are dirty bits in calldata
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Seems that at least Solidity 0.5.16 silently cleans dirty bits in calldata
| if (!(zeroForOne = token0 < token1)) { | ||
| (token0, token1) = (token1, token0); | ||
| } | ||
| pool = _toPool(token0, fee, token1); |
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_toPool now requires token0 < token1, except this isn't checked. this not only optimizes runtime gas, but also contract size
| mstore(add(swapCallbackData, 0x3f), payer) | ||
| mstore(add(swapCallbackData, 0x2b), token1) | ||
| mstore(add(swapCallbackData, 0x17), fee) | ||
| mstore(add(swapCallbackData, 0x14), token0) |
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These constants are kinda brittle, but packing the callback data like this does mean that we don't have to do any cleaning. This is effectively setting the first 63 bytes of swapCallbackData to abi.encodePacked(token0, fee, token1, payer)
| assembly ("memory-safe") { | ||
| { | ||
| let firstWord := calldataload(data.offset) | ||
| token0 := shr(0x60, firstWord) | ||
| fee := shr(0x48, firstWord) | ||
| } | ||
| token1 := calldataload(add(data.offset, 0xb)) | ||
| payer := calldataload(add(data.offset, 0x1f)) | ||
| } |
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This is both more gas efficient and less contract size than the previous iteration. This goes along with the changes to _updateSwapCallbackData to use a packed encoding instead of an ABI encoding
| @@ -249,6 +290,29 @@ abstract contract SettlerPairTest is BasePairTest { | |||
| snapEnd(); | |||
| } | |||
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| function testSettler_uniswapV2_multihop() public { | |||
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Adding integration test for multihop really shows the benefit of custody optimization. It also exercises some previously untested codepaths
This PR pushed Settler over the contract size. To fix that, this PR removes support for the ZeroEx (protocol v4) VIP. Limit orders are supported by
BASIC_SELLwrapping 0xV4 OTC. There's also a significant amount of golfing performed on the UniV2 and UniV3 VIPs