Gas1-CompilerFlag-CarlosAlegreUr.md

Summary 📌

Following recent updates, client-tests have passed, achieving gas savings of 0.18%. This optimization review focused solely on the Lender.sol contract, the only one with associated tests.

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Vulnerability Details 🔍

Use via_ir = true for an Enhanced Compiler Process 🛠️

The via_ir flag in the foundry.toml file triggers a more optimized compiler. This change resulted in a 0.18% improvement over the unoptimized contract.

foundry.toml Configuration:

(options...)
remappings = [...]
via_ir = true  <-- Set flag for optimization

🚧 Note ⚠️: Enabling via_ir prolongs the compilation process. Compilation-related tasks are expected to take quite a bit more of time when this flag is active.

📘 Information ℹ️: The via_ir flag instructs Foundry to utilize Intermediate Representation (IR). IR is a low-level language bridging high-level source code and machine code. This intermediate step allows for additional optimization techniques. Thats what the _ir means in via_ir, Intermediate Representation.

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Impact 📈

Metrics derived from gas consumption of the provided tests:

Optimization Method	Optimized Gas	Original Gas	Gas Saved	% Saved
Use of via_ir	12,870,939	12,847,388	23,551	0.18%

Test by test breakdown 🧑‍🔬

🚧 Notice ⚠️: The optimization affects all the contract, so I've analyzed all the tests.

🚧 Notice ⚠️: Negative numbers in the Gas Saved column means the "optimization" increased the consumption of gas in that test. But the overall outcome in this case is positive so it can be considered an optimization.

Test Name	Optimized Gas	Original Gas	Gas Saved
LenderTest:test_startAuction	626,458	626,519	61
LenderTest:testFuzz_buyLoan	820,537	822,978	2,441
LenderTest:testFuzz_repay	508,429	509,918	1,489
LenderTest:testFail_borrowTooLarge	245,932	246,264	332
LenderTest:test_borrow	615,740	616,289	549
LenderTest:testFuzz_seize	604,236	604,712	476
LenderTest:testFuzz_borrow	247,162	247,705	543
LenderTest:test_giveLoan	851,476	853,996	2,520
LenderTest:test_seize	546,439	546,589	150
LenderTest:test_createPool	238,918	240,654	1,736
LenderTest:testFuzz_refinance	807,460	808,483	1,023
LenderTest:testFail_repayNoTokens	617,720	617,778	58
LenderTest:testFail_buyLoanTooLate	832,601	834,673	2,072
LenderTest:testFail_buyLoanRateTooHigh	832,822	835,171	2,349
LenderTest:test_repay	522,975	523,934	959
LenderTest:test_buyLoan	854,506	857,706	3,200
LenderTest:testFuzz_createPool	105,058	104,646	-412
LenderTest:testFail_borrowTooSmall	245,483	246,328	845
LenderTest:test_refinance	848,406	850,199	1,793
LenderTest:testFail_startAuction	621,394	621,888	494
LenderTest:testFail_seizeTooEarly	631,900	632,300	400
LenderTest:test_interest	621,736	622,209	473
TOTAL	12,847,388	12,870,939	23,551

Total saved percentage => 0.18%.

📘 Notice ℹ️: The percentage has been calculated with these numbers from the TOTAL:

( 23,551 / 12,870,939 ) * 100

They mean:

(totalGasSaved / originalGasCost) * 100

Forge Snapshots Used 📸

Original

LenderTest:testFail_borrowTooLarge() (gas: 246264)
LenderTest:testFail_borrowTooSmall() (gas: 246328)
LenderTest:testFail_buyLoanRateTooHigh() (gas: 835171)
LenderTest:testFail_buyLoanTooLate() (gas: 834673)
LenderTest:testFail_repayNoTokens() (gas: 617778)
LenderTest:testFail_seizeTooEarly() (gas: 632300)
LenderTest:testFail_startAuction() (gas: 621888)
LenderTest:testFuzz_borrow(uint256,uint256) (runs: 256, μ: 247705, ~: 247702)
LenderTest:testFuzz_buyLoan(uint256) (runs: 256, μ: 822978, ~: 833057)
LenderTest:testFuzz_createPool(uint256,uint256) (runs: 256, μ: 104646, ~: 22504)
LenderTest:testFuzz_refinance(uint256,uint256) (runs: 256, μ: 808483, ~: 808483)
LenderTest:testFuzz_repay(uint256) (runs: 256, μ: 509918, ~: 509917)
LenderTest:testFuzz_seize(uint256) (runs: 256, μ: 604712, ~: 605664)
LenderTest:test_borrow() (gas: 616289)
LenderTest:test_buyLoan() (gas: 857706)
LenderTest:test_createPool() (gas: 240654)
LenderTest:test_giveLoan() (gas: 853996)
LenderTest:test_interest() (gas: 622209)
LenderTest:test_refinance() (gas: 850199)
LenderTest:test_repay() (gas: 523934)
LenderTest:test_seize() (gas: 546589)
LenderTest:test_startAuction() (gas: 626519)

Optimized

LenderTest:testFail_borrowTooLarge() (gas: 245932)
LenderTest:testFail_borrowTooSmall() (gas: 245483)
LenderTest:testFail_buyLoanRateTooHigh() (gas: 832822)
LenderTest:testFail_buyLoanTooLate() (gas: 832601)
LenderTest:testFail_repayNoTokens() (gas: 617720)
LenderTest:testFail_seizeTooEarly() (gas: 631900)
LenderTest:testFail_startAuction() (gas: 621394)
LenderTest:testFuzz_borrow(uint256,uint256) (runs: 256, μ: 247162, ~: 247159)
LenderTest:testFuzz_buyLoan(uint256) (runs: 256, μ: 820537, ~: 830195)
LenderTest:testFuzz_createPool(uint256,uint256) (runs: 256, μ: 105058, ~: 22578)
LenderTest:testFuzz_refinance(uint256,uint256) (runs: 256, μ: 807460, ~: 807460)
LenderTest:testFuzz_repay(uint256) (runs: 256, μ: 508429, ~: 508428)
LenderTest:testFuzz_seize(uint256) (runs: 256, μ: 604236, ~: 605190)
LenderTest:test_borrow() (gas: 615740)
LenderTest:test_buyLoan() (gas: 854506)
LenderTest:test_createPool() (gas: 238918)
LenderTest:test_giveLoan() (gas: 851476)
LenderTest:test_interest() (gas: 621736)
LenderTest:test_refinance() (gas: 848406)
LenderTest:test_repay() (gas: 522975)
LenderTest:test_seize() (gas: 546439)
LenderTest:test_startAuction() (gas: 626458)

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Tools Used 🛠️

• Manual audit
• Forge Snapshot
• Bash scripts tailored to analyze forge snapshots.

📘 Notice ℹ️: I've personally created the bash scripts. Here is a link to the github repo Forge-Snapshots-Analyzer.

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Recommendations 🎯

Implementing the proposed gas optimizations is recommended. This benefits both end-users and the protocol in terms of cost, while ensuring protocol security remains uncompromised as tests pass consistently.

🚧 Note ⚠️: If a significant vulnerability necessitating major code changes arises, this gas optimization technique remains relevant and applicable. Nonetheless some gas analysis as the one used here is always needed to make sure it's actually saving gas.