core/types: simplify CalcRequestsHash

Co-authored-by: Shude Li <islishude@gmail.com>

core/types/block.go

@@ -459,24 +459,15 @@ func CalcUncleHash(uncles []*Header) common.Hash {
 
 // CalcRequestsHash creates the block requestsHash value for a list of requests.
 func CalcRequestsHash(requests [][]byte) common.Hash {
-	// compute intermediate hashes
-	hashes := make([][32]byte, len(requests))
-	h := sha256.New()
-	for i, item := range requests {
-		h.Reset()
-		h.Write(item)
-		var sum [32]byte
-		h.Sum(sum[:0])
-		hashes[i] = sum
+	h1, h2 := sha256.New(), sha256.New()
+	var buf common.Hash
+	for _, item := range requests {
+		h1.Reset()
+		h1.Write(item)
+		h2.Write(h1.Sum(buf[:0]))
 	}
-	// final hash
-	h.Reset()
-	for _, hash := range hashes {
-		h.Write(hash[:])
-	}
-	var result common.Hash
-	h.Sum(result[:0])
-	return result
+	h2.Sum(buf[:0])
+	return buf
 }
 
 // NewBlockWithHeader creates a block with the given header data. The