Remove variable assignment for constant access in assembly (#722)

* Remove variable assignment for constant access in assembly (#719)

* refactor: Remove unnecessary gas cost incurred when loading a constant to a variable

* Updata gas snap data

* Formatting

* refactor: Remove unnecessary parenthesis

* regenerate gas snapshots

---------

Co-authored-by: HC <97586838+havi-kim@users.noreply.github.com>

src/libraries/Lock.sol

@@ -7,27 +7,24 @@ import {IHooks} from "../interfaces/IHooks.sol";
 /// TODO: This library can be deleted when we have the transient keyword support in solidity.
 library Lock {
     // The slot holding the unlocked state, transiently. uint256(keccak256("Unlocked")) - 1;
-    uint256 constant IS_UNLOCKED_SLOT = uint256(0xc090fc4683624cfc3884e9d8de5eca132f2d0ec062aff75d43c0465d5ceeab23);
+    uint256 constant IS_UNLOCKED_SLOT = 0xc090fc4683624cfc3884e9d8de5eca132f2d0ec062aff75d43c0465d5ceeab23;
 
     function unlock() internal {
-        uint256 slot = IS_UNLOCKED_SLOT;
         assembly {
             // unlock
-            tstore(slot, true)
+            tstore(IS_UNLOCKED_SLOT, true)
         }
     }
 
     function lock() internal {
-        uint256 slot = IS_UNLOCKED_SLOT;
         assembly {
-            tstore(slot, false)
+            tstore(IS_UNLOCKED_SLOT, false)
         }
     }
 
     function isUnlocked() internal view returns (bool unlocked) {
-        uint256 slot = IS_UNLOCKED_SLOT;
         assembly {
-            unlocked := tload(slot)
+            unlocked := tload(IS_UNLOCKED_SLOT)
         }
     }
 }

src/libraries/NonZeroDeltaCount.sol

@@ -8,33 +8,29 @@ import {IHooks} from "../interfaces/IHooks.sol";
 /// TODO: This library can be deleted when we have the transient keyword support in solidity.
 library NonZeroDeltaCount {
     // The slot holding the number of nonzero deltas. uint256(keccak256("NonzeroDeltaCount")) - 1
-    uint256 constant NONZERO_DELTA_COUNT_SLOT =
-        uint256(0x7d4b3164c6e45b97e7d87b7125a44c5828d005af88f9d751cfd78729c5d99a0b);
+    uint256 constant NONZERO_DELTA_COUNT_SLOT = 0x7d4b3164c6e45b97e7d87b7125a44c5828d005af88f9d751cfd78729c5d99a0b;
 
     function read() internal view returns (uint256 count) {
-        uint256 slot = NONZERO_DELTA_COUNT_SLOT;
         assembly {
-            count := tload(slot)
+            count := tload(NONZERO_DELTA_COUNT_SLOT)
         }
     }
 
     function increment() internal {
-        uint256 slot = NONZERO_DELTA_COUNT_SLOT;
         assembly {
-            let count := tload(slot)
+            let count := tload(NONZERO_DELTA_COUNT_SLOT)
             count := add(count, 1)
-            tstore(slot, count)
+            tstore(NONZERO_DELTA_COUNT_SLOT, count)
         }
     }
 
     /// @notice Potential to underflow.
     /// Current usage ensures this will not happen because we call decrement with known boundaries (only up to the number of times we call increment).
     function decrement() internal {
-        uint256 slot = NONZERO_DELTA_COUNT_SLOT;
         assembly {
-            let count := tload(slot)
+            let count := tload(NONZERO_DELTA_COUNT_SLOT)
             count := sub(count, 1)
-            tstore(slot, count)
+            tstore(NONZERO_DELTA_COUNT_SLOT, count)
         }
     }
 }

src/libraries/Reserves.sol

@@ -8,7 +8,7 @@ library Reserves {
     using CustomRevert for bytes4;
 
     /// uint256(keccak256("ReservesOf")) - 1
-    uint256 constant RESERVES_OF_SLOT = uint256(0x1e0745a7db1623981f0b2a5d4232364c00787266eb75ad546f190e6cebe9bd95);
+    uint256 constant RESERVES_OF_SLOT = 0x1e0745a7db1623981f0b2a5d4232364c00787266eb75ad546f190e6cebe9bd95;
     /// @notice The transient reserves for pools with no balance is set to the max as a sentinel to track that it has been synced.
     uint256 public constant ZERO_BALANCE = type(uint256).max;
 
@@ -33,9 +33,8 @@ library Reserves {
     }
 
     function _getKey(Currency currency) private pure returns (bytes32 key) {
-        uint256 slot = RESERVES_OF_SLOT;
         assembly ("memory-safe") {
-            mstore(0, slot)
+            mstore(0, RESERVES_OF_SLOT)
             mstore(32, currency)
             key := keccak256(0, 64)
         }

src/libraries/TransientStateLibrary.sol

@@ -24,10 +24,9 @@ library TransientStateLibrary {
     /// @dev returns 0 if the reserves are not synced
     /// @dev returns type(uint256).max if the reserves are synced but the value is 0
     function getReserves(IPoolManager manager, Currency currency) internal view returns (uint256) {
-        bytes32 slot = RESERVES_OF_SLOT;
         bytes32 key;
         assembly {
-            mstore(0, slot)
+            mstore(0, RESERVES_OF_SLOT)
             mstore(32, currency)
             key := keccak256(0, 64)
         }