Optimize CurrencyLibrary.transfer (#717)

* Optimize `CurrencyLibrary.transfer` (#710)

* Refactor ETH transfer in `CurrencyLibrary`

The ETH transfer process in the Currency.sol file is now refactored using memory-safe assembly code. A new approach has been introduced to handle the transfer failure, instead of just setting the `success` variable value, the process now directly reverts with a `NativeTransferFailed` error. This ensures a more robust and reliable transfer process.

* Refactor ERC20 transfer error handling

The code has been streamlined by removing the `success` variable used in the ERC20 transfer method, and directly integrating the error handling into the function call. This change helps minimize unnecessary variable usage and allows more immediate error feedback, improving the program's efficiency and clarity.

* Use Solady `SafeTransferLib.safeTransfer`

---------

Co-authored-by: Daniel Gretzke <daniel@gretzke.de>

* regenerate gas snapshots

* update commit to audited version of solady

* more accurate descriptions of modifications made to code

* add code explanation

* regenerate gas snapshots

---------

Co-authored-by: Shuhui Luo <107524008+shuhuiluo@users.noreply.github.com>

Author: gretzke

.forge-snapshots/addLiquidity CA fee.snap

@@ -1 +1 @@
-326027
+325929

.forge-snapshots/addLiquidity with native token.snap

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-139529
+139505

.forge-snapshots/erc20 collect protocol fees.snap

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-57275
+57229

.forge-snapshots/native collect protocol fees.snap

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-59520
+59496

.forge-snapshots/poolManager bytecode size.snap

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-19871
+19837

.forge-snapshots/removeLiquidity CA fee.snap

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+181448

.forge-snapshots/removeLiquidity with empty hook.snap

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+135835

.forge-snapshots/removeLiquidity with native token.snap

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-115761
+115664

.forge-snapshots/simple removeLiquidity some liquidity remains.snap

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-96504
+96455

.forge-snapshots/simple removeLiquidity.snap

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+88495

.forge-snapshots/simple swap with native.snap

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-114348
+114299

.forge-snapshots/simple swap.snap

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+129464

.forge-snapshots/swap CA custom curve + swap noop.snap

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-132045
+131947

.forge-snapshots/swap CA fee on unspecified.snap

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-178951
+178853

.forge-snapshots/swap against liquidity with native token.snap

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-110009
+109936

.forge-snapshots/swap against liquidity.snap

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-121356
+121307

.forge-snapshots/swap burn 6909 for input.snap

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+132695

.forge-snapshots/swap burn native 6909 for input.snap

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-122135
+122086

.forge-snapshots/swap skips hook call if hook is caller.snap

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+216627

.forge-snapshots/swap with dynamic fee.snap

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+144737

.forge-snapshots/swap with hooks.snap

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+138307

.forge-snapshots/swap with lp fee and protocol fee.snap

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.forge-snapshots/swap with return dynamic fee.snap

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.forge-snapshots/update dynamic fee in before swap.snap

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-154464
+154415

src/types/Currency.sol

@@ -36,43 +36,38 @@ library CurrencyLibrary {
     Currency public constant NATIVE = Currency.wrap(address(0));
 
     function transfer(Currency currency, address to, uint256 amount) internal {
-        // implementation from
-        // https://github.com/transmissions11/solmate/blob/e8f96f25d48fe702117ce76c79228ca4f20206cb/src/utils/SafeTransferLib.sol
+        // altered from https://github.com/Vectorized/solady/blob/89101d53b7c8784cca935c1f2f6403639cee48b2/src/utils/SafeTransferLib.sol
+        // modified custom error selectors
 
-        bool success;
         if (currency.isNative()) {
+            /// @solidity memory-safe-assembly
             assembly {
-                // Transfer the ETH and store if it succeeded or not.
-                success := call(gas(), to, amount, 0, 0, 0, 0)
+                // Transfer the ETH and revert if it fails.
+                if iszero(call(gas(), to, amount, 0x00, 0x00, 0x00, 0x00)) {
+                    mstore(0x00, 0xf4b3b1bc) // `NativeTransferFailed()`.
+                    revert(0x1c, 0x04)
+                }
             }
-
-            if (!success) revert NativeTransferFailed();
         } else {
+            /// @solidity memory-safe-assembly
             assembly {
-                // We'll write our calldata to this slot below, but restore it later.
-                let memPointer := mload(0x40)
-
-                // Write the abi-encoded calldata into memory, beginning with the function selector.
-                mstore(0, 0xa9059cbb00000000000000000000000000000000000000000000000000000000)
-                mstore(4, to) // Append the "to" argument.
-                mstore(36, amount) // Append the "amount" argument.
-
-                success :=
-                    and(
-                        // Set success to whether the call reverted, if not we check it either
-                        // returned exactly 1 (can't just be non-zero data), or had no return data.
-                        or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
-                        // We use 68 because that's the total length of our calldata (4 + 32 * 2)
-                        // Counterintuitively, this call() must be positioned after the or() in the
-                        // surrounding and() because and() evaluates its arguments from right to left.
-                        call(gas(), currency, 0, 0, 68, 0, 32)
+                mstore(0x14, to) // Store the `to` address in [0x20, 0x34).
+                mstore(0x34, amount) // Store the `amount` argument in [0x34, 0x54).
+                // Store the selector of `transfer(address,uint256)` in [0x10, 0x14).
+                // also cleans the upper bits of `to`
+                mstore(0x00, 0xa9059cbb000000000000000000000000)
+                // Perform the transfer, reverting upon failure.
+                if iszero(
+                    and( // The arguments of `and` are evaluated from right to left.
+                        or(eq(mload(0x00), 1), iszero(returndatasize())), // Returned 1 or nothing.
+                        call(gas(), currency, 0, 0x10, 0x44, 0x00, 0x20)
                     )
-
-                mstore(0x60, 0) // Restore the zero slot to zero.
-                mstore(0x40, memPointer) // Restore the memPointer.
+                ) {
+                    mstore(0x00, 0xf27f64e4) // `ERC20TransferFailed()`.
+                    revert(0x1c, 0x04)
+                }
+                mstore(0x34, 0) // Restore the part of the free memory pointer that was overwritten.
             }
-
-            if (!success) revert ERC20TransferFailed();
         }
     }