add

core/vm/memory.go

@@ -79,13 +79,20 @@ func (m *Memory) Set32(offset uint64, val *uint256.Int) {
 
 // Resize grows the memory to the requested size.
 func (m *Memory) Resize(size uint64) {
-	if uint64(len(m.store)) < size {
+		if size <= uint64(len(m.store)) {
-		if uint64(cap(m.store)) >= size {
+		return
-			m.store = m.store[:size]
-		} else {
-			m.store = append(m.store, make([]byte, size-uint64(len(m.store)))...)
-		}
 	}
+
+	if size <= uint64(cap(m.store)) {
+		prevLen := len(m.store)
+		m.store = m.store[:size]
+		clear(m.store[prevLen:])
+		return
+	}
+
+	store := make([]byte, size)
+	copy(store, m.store)
+	m.store = store
 }
 
 // GetCopy returns offset + size as a new slice

core/vm/new_bench.txt

@@ -0,0 +1,7 @@
+goos: linux
+goarch: amd64
+pkg: github.com/ethereum/go-ethereum/core/vm
+cpu: Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
+BenchmarkResize-8   	  876326	     89800 ns/op	  442142 B/op	       1 allocs/op
+BenchmarkResize-8   	signal: interrupt
+FAIL	github.com/ethereum/go-ethereum/core/vm	154.281s

core/vm/old_bench.txt

@@ -0,0 +1,16 @@
+goos: linux
+goarch: amd64
+pkg: github.com/ethereum/go-ethereum/core/vm
+cpu: Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
+BenchmarkResize-8   	513681400	         4.756 ns/op	       5 B/op	       0 allocs/op
+BenchmarkResize-8   	747650196	         2.313 ns/op	       6 B/op	       0 allocs/op
+BenchmarkResize-8   	907757728	         1.302 ns/op	       5 B/op	       0 allocs/op
+BenchmarkResize-8   	906696679	         1.356 ns/op	       5 B/op	       0 allocs/op
+BenchmarkResize-8   	832139062	         2.823 ns/op	       5 B/op	       0 allocs/op
+BenchmarkResize-8   	943258486	         2.120 ns/op	       6 B/op	       0 allocs/op
+BenchmarkResize-8   	1000000000	         1.619 ns/op	       5 B/op	       0 allocs/op
+BenchmarkResize-8   	982619973	         1.388 ns/op	       5 B/op	       0 allocs/op
+BenchmarkResize-8   	761129438	         1.351 ns/op	       6 B/op	       0 allocs/op
+BenchmarkResize-8   	943591894	         1.643 ns/op	       6 B/op	       0 allocs/op
+PASS
+ok  	github.com/ethereum/go-ethereum/core/vm	37.469s