From 0c82928981028e8b32b5852c38b095d2e0d26b04 Mon Sep 17 00:00:00 2001 From: Marius van der Wijden Date: Wed, 24 Jun 2020 19:58:28 +0000 Subject: [PATCH] core/vm: fix incorrect computation of BLS discount (#21253) * core/vm: fix incorrect computation of discount During testing on Yolov1 we found that the way geth calculates the discount is not in line with the specification. Basically what we did is calculate 128 * Bls12381GXMulGas * discount / 1000 whenever we received more than 128 pairs of values. Correct would be to calculate k * Bls12381... for k > 128. * core/vm: better logic for discount calculation * core/vm: better calculation logic, added worstcase benchmarks * core/vm: better benchmarking logic --- core/vm/contracts.go | 18 ++++++++------- core/vm/contracts_test.go | 47 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+), 8 deletions(-) diff --git a/core/vm/contracts.go b/core/vm/contracts.go index 5f0d9095dd..6493d45895 100644 --- a/core/vm/contracts.go +++ b/core/vm/contracts.go @@ -620,11 +620,12 @@ func (c *bls12381G1MultiExp) RequiredGas(input []byte) uint64 { return 0 } // Lookup discount value for G1 point, scalar value pair length - maxDiscountLen := len(params.Bls12381MultiExpDiscountTable) - if k > maxDiscountLen { - k = maxDiscountLen + var discount uint64 + if dLen := len(params.Bls12381MultiExpDiscountTable); k < dLen { + discount = params.Bls12381MultiExpDiscountTable[k-1] + } else { + discount = params.Bls12381MultiExpDiscountTable[dLen-1] } - discount := params.Bls12381MultiExpDiscountTable[k-1] // Calculate gas and return the result return (uint64(k) * params.Bls12381G1MulGas * discount) / 1000 } @@ -750,11 +751,12 @@ func (c *bls12381G2MultiExp) RequiredGas(input []byte) uint64 { return 0 } // Lookup discount value for G2 point, scalar value pair length - maxDiscountLen := len(params.Bls12381MultiExpDiscountTable) - if k > maxDiscountLen { - k = maxDiscountLen + var discount uint64 + if dLen := len(params.Bls12381MultiExpDiscountTable); k < dLen { + discount = params.Bls12381MultiExpDiscountTable[k-1] + } else { + discount = params.Bls12381MultiExpDiscountTable[dLen-1] } - discount := params.Bls12381MultiExpDiscountTable[k-1] // Calculate gas and return the result return (uint64(k) * params.Bls12381G2MulGas * discount) / 1000 } diff --git a/core/vm/contracts_test.go b/core/vm/contracts_test.go index 139de99e54..65a9f8b797 100644 --- a/core/vm/contracts_test.go +++ b/core/vm/contracts_test.go @@ -23,6 +23,7 @@ import ( "io/ioutil" "math/big" "testing" + "time" "github.com/ethereum/go-ethereum/common" ) @@ -142,6 +143,7 @@ func benchmarkPrecompiled(addr string, test precompiledTest, bench *testing.B) { bench.Run(fmt.Sprintf("%s-Gas=%d", test.Name, contract.Gas), func(bench *testing.B) { bench.ReportAllocs() + start := time.Now().Nanosecond() bench.ResetTimer() for i := 0; i < bench.N; i++ { contract.Gas = reqGas @@ -149,7 +151,13 @@ func benchmarkPrecompiled(addr string, test precompiledTest, bench *testing.B) { res, err = RunPrecompiledContract(p, data, contract) } bench.StopTimer() + elapsed := float64(time.Now().Nanosecond() - start) + if elapsed < 1 { + elapsed = 1 + } + gasUsed := reqGas * uint64(bench.N) bench.ReportMetric(float64(reqGas), "gas/op") + bench.ReportMetric(float64(gasUsed*1000)/elapsed, "mgas/s") //Check if it is correct if err != nil { bench.Error(err) @@ -320,3 +328,42 @@ func loadJsonFail(name string) ([]precompiledFailureTest, error) { err = json.Unmarshal(data, &testcases) return testcases, err } + +// BenchmarkPrecompiledBLS12381G1MultiExpWorstCase benchmarks the worst case we could find that still fits a gaslimit of 10MGas. +func BenchmarkPrecompiledBLS12381G1MultiExpWorstCase(b *testing.B) { + task := "0000000000000000000000000000000008d8c4a16fb9d8800cce987c0eadbb6b3b005c213d44ecb5adeed713bae79d606041406df26169c35df63cf972c94be1" + + "0000000000000000000000000000000011bc8afe71676e6730702a46ef817060249cd06cd82e6981085012ff6d013aa4470ba3a2c71e13ef653e1e223d1ccfe9" + + "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF" + input := task + for i := 0; i < 4787; i++ { + input = input + task + } + testcase := precompiledTest{ + Input: input, + Expected: "0000000000000000000000000000000005a6310ea6f2a598023ae48819afc292b4dfcb40aabad24a0c2cb6c19769465691859eeb2a764342a810c5038d700f18000000000000000000000000000000001268ac944437d15923dc0aec00daa9250252e43e4b35ec7a19d01f0d6cd27f6e139d80dae16ba1c79cc7f57055a93ff5", + Name: "WorstCaseG1", + NoBenchmark: false, + } + benchmarkPrecompiled("0c", testcase, b) +} + +// BenchmarkPrecompiledBLS12381G2MultiExpWorstCase benchmarks the worst case we could find that still fits a gaslimit of 10MGas. +func BenchmarkPrecompiledBLS12381G2MultiExpWorstCase(b *testing.B) { + task := "000000000000000000000000000000000d4f09acd5f362e0a516d4c13c5e2f504d9bd49fdfb6d8b7a7ab35a02c391c8112b03270d5d9eefe9b659dd27601d18f" + + "000000000000000000000000000000000fd489cb75945f3b5ebb1c0e326d59602934c8f78fe9294a8877e7aeb95de5addde0cb7ab53674df8b2cfbb036b30b99" + + "00000000000000000000000000000000055dbc4eca768714e098bbe9c71cf54b40f51c26e95808ee79225a87fb6fa1415178db47f02d856fea56a752d185f86b" + + "000000000000000000000000000000001239b7640f416eb6e921fe47f7501d504fadc190d9cf4e89ae2b717276739a2f4ee9f637c35e23c480df029fd8d247c7" + + "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF" + input := task + for i := 0; i < 1040; i++ { + input = input + task + } + + testcase := precompiledTest{ + Input: input, + Expected: "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", + Name: "WorstCaseG2", + NoBenchmark: false, + } + benchmarkPrecompiled("0f", testcase, b) +}