bitwise optimizations (#120)

* bitwise optimizations

* gas

* remove repeat nonce test

.forge-snapshots/permitBatchTransferFromMultipleTokens.snap

@@ -1 +1 @@
-143701
+143548

.forge-snapshots/permitBatchTransferFromSingleToken.snap

@@ -1 +1 @@
-89017
+88864

.forge-snapshots/permitTransferFromBatchTypedWitness.snap

@@ -1 +1 @@
-121451
+121298

.forge-snapshots/permitTransferFromCompactSig.snap

@@ -1 +1 @@
-88685
+88532

.forge-snapshots/permitTransferFromSingleToken.snap

@@ -1 +1 @@
-88737
+88584

.forge-snapshots/permitTransferFromTypedWitness.snap

@@ -1 +1 @@
-91157
+91004

.forge-snapshots/single recipient 2 tokens.snap

@@ -1 +1 @@
-118757
+118604

.forge-snapshots/single recipient many tokens.snap

@@ -1 +1 @@
-134435
+134282

.gas-snapshot

@@ -28,13 +28,13 @@ CompactSignature:testCompactSignature27() (gas: 253)
 CompactSignature:testCompactSignature28() (gas: 141)
 EIP712Test:testDomainSeparator() (gas: 5759)
 EIP712Test:testDomainSeparatorAfterFork() (gas: 10652)
-NonceBitmapTest:testHighNonces() (gas: 36088)
-NonceBitmapTest:testInvalidateFullWord() (gas: 62606)
-NonceBitmapTest:testInvalidateNonzeroWord() (gas: 85721)
-NonceBitmapTest:testLowNonces() (gas: 41019)
-NonceBitmapTest:testNonceWordBoundary() (gas: 57948)
-NonceBitmapTest:testUseTwoRandomNonces(uint256,uint256) (runs: 256, μ: 49304, ~: 51829)
-NonceBitmapTest:testUsingNonceTwiceFails(uint256) (runs: 256, μ: 32616, ~: 32616)
+NonceBitmapTest:testHighNonces() (gas: 35958)
+NonceBitmapTest:testInvalidateFullWord() (gas: 62805)
+NonceBitmapTest:testInvalidateNonzeroWord() (gas: 85285)
+NonceBitmapTest:testLowNonces() (gas: 40671)
+NonceBitmapTest:testNonceWordBoundary() (gas: 42042)
+NonceBitmapTest:testUseTwoRandomNonces(uint256,uint256) (runs: 256, μ: 48832, ~: 51523)
+NonceBitmapTest:testUsingNonceTwiceFails(uint256) (runs: 256, μ: 21775, ~: 21798)
 Permit2LibTest:testOZSafePermit() (gas: 24311)
 Permit2LibTest:testOZSafePermitPlusOZSafeTransferFrom() (gas: 129066)
 Permit2LibTest:testOZSafeTransferFrom() (gas: 38787)
@@ -50,29 +50,29 @@ Permit2LibTest:testTransferFrom2() (gas: 38404)
 Permit2LibTest:testTransferFrom2Full() (gas: 53437)
 Permit2LibTest:testTransferFrom2InvalidAmount() (gas: 12519)
 Permit2LibTest:testTransferFrom2NonPermitToken() (gas: 53305)
-SignatureTransferTest:testGasMultiplePermitBatchTransferFrom() (gas: 271182)
-SignatureTransferTest:testGasSinglePermitBatchTransferFrom() (gas: 186398)
-SignatureTransferTest:testGasSinglePermitTransferFrom() (gas: 124117)
-SignatureTransferTest:testInvalidateUnorderedNonces() (gas: 56562)
-SignatureTransferTest:testPermitBatchMultiPermitSingleTransfer() (gas: 133761)
-SignatureTransferTest:testPermitBatchTransferFrom() (gas: 162210)
-SignatureTransferTest:testPermitBatchTransferFromSingleRecipient() (gas: 190511)
-SignatureTransferTest:testPermitBatchTransferFromTypedWitness() (gas: 242649)
-SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidType() (gas: 87340)
-SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidTypeHash() (gas: 86825)
-SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidTypeName() (gas: 88298)
-SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidWitness() (gas: 88343)
+SignatureTransferTest:testGasMultiplePermitBatchTransferFrom() (gas: 271029)
+SignatureTransferTest:testGasSinglePermitBatchTransferFrom() (gas: 186245)
+SignatureTransferTest:testGasSinglePermitTransferFrom() (gas: 123964)
+SignatureTransferTest:testInvalidateUnorderedNonces() (gas: 41108)
+SignatureTransferTest:testPermitBatchMultiPermitSingleTransfer() (gas: 133608)
+SignatureTransferTest:testPermitBatchTransferFrom() (gas: 162057)
+SignatureTransferTest:testPermitBatchTransferFromSingleRecipient() (gas: 190358)
+SignatureTransferTest:testPermitBatchTransferFromTypedWitness() (gas: 242496)
+SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidType() (gas: 87187)
+SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidTypeHash() (gas: 86672)
+SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidTypeName() (gas: 88145)
+SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidWitness() (gas: 88190)
 SignatureTransferTest:testPermitBatchTransferInvalidAmountsLengthMismatch() (gas: 43760)
-SignatureTransferTest:testPermitBatchTransferMultiAddr() (gas: 160606)
-SignatureTransferTest:testPermitBatchTransferSingleRecipientManyTokens() (gas: 212666)
-SignatureTransferTest:testPermitTransferFrom() (gas: 93208)
-SignatureTransferTest:testPermitTransferFromCompactSig() (gas: 124181)
-SignatureTransferTest:testPermitTransferFromIncorrectSigLength() (gas: 51430)
-SignatureTransferTest:testPermitTransferFromInvalidNonce() (gas: 93237)
-SignatureTransferTest:testPermitTransferFromRandomNonceAndAmount(uint256,uint128) (runs: 256, μ: 95864, ~: 96840)
-SignatureTransferTest:testPermitTransferFromToSpender() (gas: 93516)
-SignatureTransferTest:testPermitTransferFromTypedWitness() (gas: 127964)
-SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidType() (gas: 58690)
-SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidTypeName() (gas: 59744)
-SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidTypehash() (gas: 57680)
-SignatureTransferTest:testPermitTransferSpendLessThanFull(uint256,uint128) (runs: 256, μ: 98199, ~: 99917)
+SignatureTransferTest:testPermitBatchTransferMultiAddr() (gas: 160453)
+SignatureTransferTest:testPermitBatchTransferSingleRecipientManyTokens() (gas: 212513)
+SignatureTransferTest:testPermitTransferFrom() (gas: 93055)
+SignatureTransferTest:testPermitTransferFromCompactSig() (gas: 124028)
+SignatureTransferTest:testPermitTransferFromIncorrectSigLength() (gas: 51277)
+SignatureTransferTest:testPermitTransferFromInvalidNonce() (gas: 73272)
+SignatureTransferTest:testPermitTransferFromRandomNonceAndAmount(uint256,uint128) (runs: 256, μ: 95711, ~: 96687)
+SignatureTransferTest:testPermitTransferFromToSpender() (gas: 93363)
+SignatureTransferTest:testPermitTransferFromTypedWitness() (gas: 127811)
+SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidType() (gas: 58537)
+SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidTypeName() (gas: 59591)
+SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidTypehash() (gas: 57527)
+SignatureTransferTest:testPermitTransferSpendLessThanFull(uint256,uint128) (runs: 256, μ: 98046, ~: 99764)

src/SignatureTransfer.sol

@@ -146,18 +146,17 @@ contract SignatureTransfer is ISignatureTransfer, EIP712 {
     /// @dev The last 8 bits of the nonce value is the position of the bit in the bitmap
     function bitmapPositions(uint256 nonce) private pure returns (uint256 wordPos, uint256 bitPos) {
         wordPos = uint248(nonce >> 8);
-        bitPos = uint8(nonce & 255);
+        bitPos = uint8(nonce);
     }
 
     /// @notice Checks whether a nonce is taken and sets the bit at the bit position in the bitmap at the word position
     /// @param from The address to use the nonce at
     /// @param nonce The nonce to spend
     function _useUnorderedNonce(address from, uint256 nonce) internal {
         (uint256 wordPos, uint256 bitPos) = bitmapPositions(nonce);
-        uint256 bitmap = nonceBitmap[from][wordPos];
+        uint256 bit = 1 << bitPos;
+        uint256 flipped = nonceBitmap[from][wordPos] ^= bit;
 
-        if ((bitmap >> bitPos) & 1 == 1) revert InvalidNonce();
-
-        nonceBitmap[from][wordPos] = bitmap | (1 << bitPos);
+        if (flipped & bit == 0) revert InvalidNonce();
     }
 }