core/vm: reuse Memory instances

core/vm/interpreter.go

@@ -198,6 +198,7 @@ func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (
 	// they are returned to the pools
 	defer func() {
 		returnStack(stack)
+		mem.Free()
 	}()
 	contract.Input = input
 

core/vm/memory.go

@@ -17,9 +17,19 @@
 package vm
 
 import (
+	"sync"
+
 	"github.com/holiman/uint256"
 )
 
+var memoryPool = sync.Pool{
+	New: func() any {
+		return &Memory{
+			store: make([]byte, 0),
+		}
+	},
+}
+
 // Memory implements a simple memory model for the ethereum virtual machine.
 type Memory struct {
 	store       []byte
@@ -28,7 +38,18 @@ type Memory struct {
 
 // NewMemory returns a new memory model.
 func NewMemory() *Memory {
-	return &Memory{}
+	return memoryPool.Get().(*Memory)
+}
+
+// Free returns the memory to the pool.
+func (m *Memory) Free() {
+	// To reduce peak allocation, return only smaller memory instances to the pool.
+	const maxBufferSize = 16 << 10
+	if cap(m.store) <= maxBufferSize {
+		m.store = m.store[:0]
+		m.lastGasCost = 0
+		memoryPool.Put(m)
+	}
 }
 
 // Set sets offset + size to value