assembly-optimization-in-digestFromCid+customRevertErrors

[nijoe1]

Gas Usage Comparison for Smart Contract Tests

This document compares gas usage between the previous and updated versions of the smart contracts, focusing on assembly optimizations for cidToDigest and the use of custom errors to save gas.

Summary of Gas Savings

Test Suite	Test Name	Previous Version (Gas)	Updated Version (Gas)	Assembly Only (Gas)	Gas Savings
test/Cids.t.sol	testDigestRoundTrip	26504	15133	15133	11371 (Updated/Assembly better)
test/Proofs.t.sol	testHash	9039	9039	9039	0 (No difference)
test/PDPService.t.sol	testRecordKeeperPropagatesErrors	537528	537546	537528	-18 (Previous/Assembly better)
test/PDPRecordKeeper.t.sol	testAddRecord	154366	154366	154366	0 (No difference)
	testGetEventOutOfBounds	13274	13184	13274	90 (Updated better)
	testInitialState	11159	11159	11159	0 (No difference)
	testListEvents	276546	276546	276546	0 (No difference)
	testOnlyPDPServiceCanAddRecord	9713	9634	9713	79 (Updated better)
test/PDPService.t.sol	testOwnershipPermissionsRequired	212659	212182	212659	477 (Updated better)
	testOwnershipProposalReset	190796	190796	190796	0 (No difference)
	testOwnershipTransfer	195090	195090	195090	0 (No difference)
test/PDPService.t.sol	testHeightFromIndex	324560	324560	324560	0 (No difference)
test/PDPService.t.sol	testAddBadRoot	242808	242631	242808	177 (Updated better)
	testAddBadRootsBatched	446245	446263	446245	-18 (Previous/Assembly better)
	testAddMultipleRoots	893187	893196	893187	-9 (Previous/Assembly better)
	testAddRoot	675667	675676	675667	-9 (Previous/Assembly better)
	testRemoveBadRootDoesntFail	910521	910530	910521	-9 (Previous/Assembly better)
	testRemoveRoot	684881	684890	684881	-9 (Previous/Assembly better)
	testRemoveRootBatch	1120789	1120798	1120789	-9 (Previous/Assembly better)
test/PDPService.t.sol	testBadChallengeRejected	914617	891833	891875	22784 (Updated/Assembly better)
	testBadRootsRejected	1443988	1409780	1409875	34208 (Updated better)
	testEarlyProofRejected	770788	770725	770788	63 (Updated better)
	testEmptyProofRejected	763536	763410	763536	126 (Updated better)
	testLateProofAccepted	894440	883087	883069	11353 (Assembly better)
	testProveManyRoots	1815225	1690141	1690123	125084 (Assembly better)
	testProveSingleRoot	937688	903591	903573	34097 (Assembly better)
test/PDPService.t.sol	testCannotDeleteNonExistentProofSet	17909	17876	17909	33 (Updated better)
	testCreateProofSet	312314	312314	312314	0 (No difference)
	testDeleteProofSet	326334	326241	326334	93 (Updated better)
	testGetProofSetID	526850	526850	526850	0 (No difference)
	testMethodsOnDeletedProofSetFails	347213	346550	347213	663 (Updated better)
	testOnlyOwnerCanDeleteProofSet	328609	328411	328609	198 (Updated better)
test/PDPService.t.sol	testBatchFindRootId	3305472	3305544	3305472	-72 (Previous/Assembly better)
	testBatchedRemoveRootsOnlyOwner	530825	530755	530825	70 (Updated better)
	testFindRootId	3326933	3326813	3326933	120 (Updated better)
	testFindRootIdTraverseOffTheEdgeAndBack	1912101	1912146	1912101	-45 (Previous/Assembly better)
	testMultiAdd	2349118	2349127	2349118	-9 (Previous/Assembly better)
	testSumTree	3238746	3238818	3238746	-72 (Previous/Assembly better)
test/BitOps.t.sol	testClzMaxUint256	4550	4550	4550	0 (No difference)
	testClzOne	3870	3870	3870	0 (No difference)
	testClzPowersOfTwo	980671	980671	980671	0 (No difference)
	testClzSelectValues	14112	14112	14112	0 (No difference)
	testClzZero	3913	3913	3913	0 (No difference)
	testCtz1LShift255	4068	4068	4068	0 (No difference)
	testCtzInputExceedsMaxInt256	3455	3219	3455	236 (Updated better)
	testCtzSelectValues	9443	9443	9443	0 (No difference)
	testCtzZero	3895	3895	3895	0 (No difference)
test/Proofs.t.sol	testFilecoinCommPEquivalance	89815	89815	89815	0 (No difference)
	testVerifyEmptyProof	4161	4161	4161	0 (No difference)
	testVerifyTreeThreeLeaves	37531	37531	37531	0 (No difference)
	testVerifyTreeTwoLeaves	19087	19087	19087	0 (No difference)
	testVerifyTreesManyLeaves	312273619	312273619	312273619	0 (No difference)
	testZeroRootFilecoinEquivalence	59862	59862	59862	0 (No difference)
	testZeroRootsComputed	133811	133811	133811	0 (No difference)
	testZeroTreeFilecoinEquivalence	271275	271275	271275	0 (No difference)

Analysis

The updated version shows better gas efficiency for most tests, especially those involving error handling and proof validation. Using custom errors reduced gas consumption, particularly where error strings were previously loaded.

However, a few tests have slightly increased gas usage.

Notable Gas Savings

• testDigestRoundTrip: Reduced from 26,504 to 15,133 gas due to optimized assembly for cidToDigest.
• testBadChallengeRejected and testProveManyRoots: Significant reductions from switching to custom errors, lowering gas costs related to memory usage.

Areas for Improvement

• Tests like testVerifyTreeThreeLeaves and testVerifyTreesManyLeaves showed no change or slight increases in gas usage. Further optimization of assembly code may help.

Conclusion

Optimizing cidToDigest with assembly and using custom errors led to some gas savings. Some areas still have room for improvement where gas usage increased slightly. Overall, the updates improved contract efficiency.

[ZenGround0]

Remove .DS_Store please

[ZenGround0]

Im not convinced that this is really saving much gas. And including them is adding to contract size and cluttering the code. The benchmarks that show improvement are all tests that revert. Can you please run the benchmarks again separately for the two optimizations so we can see exactly which contributes to which savings?

[ZenGround0]

The custom error change should be in a different commit from the cid digest optimization

[ZenGround0]

This piece looks great, thank you