Gas Optimizations

[code423n4]

1. Use require(x) instead of require(x == true)

contracts/BlurExchange.sol: L267

contracts/ExecutionDelegate.sol: L92
L108
L124

2. Strings messages in require statements should not be longer than 32 bytes of length

contracts/BlurExchange.sol: L482

contracts/ExecutionDelegate.sol: L22

3. Place i++ in an unchecked blocks in for-loops

contracts/lib/MerkleVerifier.sol: L38

contracts/lib/EIP712.sol: L77

contracts/BlurExchange.sol: L199
L476

contracts/PolicyManager.sol: L77

4. Consider marking functions as payable if there is no risk of sending value through them

This change will save gas each time a function is called

contracts/ExecutionDelegate.sol: L36
L45

contracts/PolicyManager.sol: L25
L36

contracts/BlurExchange.sol: L43
L47
L53

5. Calldata is cheaper than memory for function input

contracts/lib/EIP712.sol: L39

contracts/lib/MerkleVerifier.sol: L20
L35

6. Function that are called only once can be inlined in the calling function

This change will save around 30 gas units

contracts/lib/MerkleVerifier.sol: L45
L49

7. Cache storage variables in function call stack to save gas

contracts/PolicyManager.sol: L71-L78

8. Prefix incrementing and decrementing costs around 6 gas less than the postfix ones

e.g. ++var is cheaper than var++

contracts/lib/MerkleVerifier.sol: L38

contracts/BlurExchange.sol: L199
L476

contracts/PolicyManager.sol: L77

contracts/lib/EIP712.sol: L77

9. Use 1 and 2 for true and false

contracts/lib/ReentrancyGuarded.sol: L10

10. public storage constant(and immutable) variable should be private

saves tons of gas on deployment

contracts/lib/EIP712.sol: L23
L26
L29

contracts/BlurExchange.sol: L57
L58
L59

11. Custom error are cheaper than string messages

contracts/BlurExchange.sol: L36
L139
L142
L143
L228
L318
L407
L424
L431
L482
L534

contracts/PolicyManager.sol: L26
L37

contracts/ExecutionDelegate.sol: L22
L77
L92
L108

contracts/lib/ReentrancyGuarded.sol: L14

12. Use constant and immutable for constants

contracts/PolicyManager.sol: L16

contracts/lib/EIP712.sol: L37

[GalloDaSballo]

5k from nonReentrant rest is negligible (immutable is incorrect)