From d3d58d9d07b3f9e38704c2a0866fc7bfa938ae16 Mon Sep 17 00:00:00 2001
From: Marius van der Wijden <m.vanderwijden@live.de>
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 644f523143..25166efe72 100644
--- a/core/vm/contracts.go
+++ b/core/vm/contracts.go
@@ -622,11 +622,12 @@ 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
}
@@ -754,11 +755,12 @@ 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 903f2746d0..1957514dc3 100644
--- a/core/vm/contracts_test.go
+++ b/core/vm/contracts_test.go
@@ -22,6 +22,7 @@ import (
"fmt"
"io/ioutil"
"testing"
+ "time"
"github.com/holiman/uint256"
@@ -143,6 +144,7 @@ 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
@@ -150,7 +152,13 @@ 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)
@@ -321,3 +329,42 @@ 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)
+}
--
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