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| author | Martin Holst Swende <martin@swende.se> | 2018-10-16 06:51:39 +0800 |
|---|---|---|
| committer | Felix Lange <fjl@users.noreply.github.com> | 2018-10-16 06:51:39 +0800 |
| commit | a352de6a08db2c68383c7b1fdcf8267184b7dcea (patch) | |
| tree | 48aa9b6533849abe5ce5c96052e42626e7432244 | |
| parent | 6a7695e3676ef8275afd5eafde6e045b7a7ab024 (diff) | |
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core/vm: add shortcuts for trivial exp cases (#16851)
| -rw-r--r-- | core/vm/instructions.go | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/core/vm/instructions.go b/core/vm/instructions.go index e94a2777b..b7c3ca532 100644 --- a/core/vm/instructions.go +++ b/core/vm/instructions.go @@ -124,10 +124,22 @@ func opSmod(pc *uint64, interpreter *EVMInterpreter, contract *Contract, memory func opExp(pc *uint64, interpreter *EVMInterpreter, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) { base, exponent := stack.pop(), stack.pop() - stack.push(math.Exp(base, exponent)) - - interpreter.intPool.put(base, exponent) - + // some shortcuts + cmpToOne := exponent.Cmp(big1) + if cmpToOne < 0 { // Exponent is zero + // x ^ 0 == 1 + stack.push(base.SetUint64(1)) + } else if base.Sign() == 0 { + // 0 ^ y, if y != 0, == 0 + stack.push(base.SetUint64(0)) + } else if cmpToOne == 0 { // Exponent is one + // x ^ 1 == x + stack.push(base) + } else { + stack.push(math.Exp(base, exponent)) + interpreter.intPool.put(base) + } + interpreter.intPool.put(exponent) return nil, nil } |