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core/vm: less alloc and copying for mstore

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This commit is contained in:
Martin Holst Swende 2018-06-10 22:33:50 +02:00
parent f9871ad4cf
commit 4f26fab1e9
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2 changed files with 21 additions and 2 deletions
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2
core/vm/instructions.go
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@ -556,7 +556,7 @@ func opMload(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *St
func opMstore(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
// pop value of the stack
mStart, val := stack.pop(), stack.pop()
memory.Set(mStart.Uint64(), 32, math.PaddedBigBytes(val, 32))
memory.Set32(mStart.Uint64(), val)
evm.interpreter.intPool.put(mStart, val)
return nil, nil

21
core/vm/memory.go
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@ -16,7 +16,12 @@
package vm
import "fmt"
import (
"fmt"
"math/big"
"github.com/ethereum/go-ethereum/common/math"
)
// Memory implements a simple memory model for the ethereum virtual machine.
type Memory struct {
@ -43,6 +48,20 @@ func (m *Memory) Set(offset, size uint64, value []byte) {
}
}
// Set32 sets the 32 bytes starting at offset to the value of val, left-padded with zeroes to
// 32 bytes.
func (m *Memory) Set32(offset uint64, val *big.Int) {
// length of store may never be less than offset + size.
// The store should be resized PRIOR to setting the memory
if 32 > uint64(len(m.store)) {
panic("INVALID memory: store empty")
}
// Zero the memory area
copy(m.store[offset:offset+32], []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0})
// Fill in relevant bits
math.ReadBits(val, m.store[offset:offset+32])
}
// Resize resizes the memory to size
func (m *Memory) Resize(size uint64) {
if uint64(m.Len()) < size {