Gas Optimizations

[code423n4]

1. state variables can be packed into fewer storage slots

If variables occupying the same slot are both written the same function or by the constructor, avoids a separate Gsset (20000 gas). Reads of the variables are also cheaper.

change the position of line 26 to after a address state variable:

• VaultTracker.sol#L26

2. state variables should be cached in stack variables rather than re-reading them from storage

marketPlace in function setMarketPlace:

• Creator.sol#L55

maturityRate in function addNotional:

• VaultTracker.sol#L59

maturityRate in function removeNotional:

• VaultTracker.sol#L93

maturityRate in function redeemInterest:

• VaultTracker.sol#L123

maturityRate in function transferNotionalFrom:

• VaultTracker.sol#L165

maturityRate in function transferNotionalFee:

• VaultTracker.sol#L222

feeChange in function setFee:

• Swivel.sol#L500

3. x = x + y is cheaper than x += y

• Erc20.sol#L92

• Erc20.sol#L114

• Erc20.sol#L197

• Erc20.sol#L202

• Erc20.sol#L87

• Erc20.sol#L109

• Erc20.sol#L209

• Erc20.sol#L214

• VaultTracker.sol#L67

• VaultTracker.sol#L68

• VaultTracker.sol#L102

• VaultTracker.sol#L174

• VaultTracker.sol#L193

• VaultTracker.sol#L194

• VaultTracker.sol#L230

• VaultTracker.sol#L234

• VaultTracker.sol#L103

• VaultTracker.sol#L175

• VaultTracker.sol#L213

• ZcToken.sol#L115

• ZcToken.sol#L134

• Swivel.sol#L121

• Swivel.sol#L158

• Swivel.sol#L193

• Swivel.sol#L222

• Swivel.sol#L287

• Swivel.sol#L318

• Swivel.sol#L348

• Swivel.sol#L383

4. better to use ++i than i++

• Erc20.sol#L154