Faster MCOPY implementation (#5630)

Faster MCOPY implementation

wire in deep call to System.arrayCopy instead of buffer copy.

Signed-off-by: Danno Ferrin <danno.ferrin@swirldslabs.com>

evm/src/main/java/org/hyperledger/besu/evm/frame/Memory.java

@@ -408,6 +408,20 @@ public void setWord(final long location, final Bytes32 bytes) {
     System.arraycopy(bytes.toArrayUnsafe(), 0, memBytes, start, Bytes32.SIZE);
   }
 
+  /**
+   * Copies one length of bytes to a new memory location, growing memory if needed.
+   *
+   * <p>Copying behaves as if the values are copied to an intermediate buffer before writing.
+   *
+   * @param dst where to copy the bytes _to_
+   * @param src where to copy the bytes _from_
+   * @param length the number of bytes to copy.
+   */
+  public void copy(final long dst, final long src, final long length) {
+    ensureCapacityForBytes(Math.max(dst, src), length);
+    System.arraycopy(memBytes, asByteIndex(src), memBytes, asByteIndex(dst), asByteLength(length));
+  }
+
   @Override
   public String toString() {
     return Bytes.wrap(memBytes).toHexString();

evm/src/main/java/org/hyperledger/besu/evm/frame/MessageFrame.java

@@ -817,6 +817,26 @@ public void writeMemory(
     }
   }
 
+  /**
+   * Copies bytes within memory.
+   *
+   * <p>Copying behaves as if the values are copied to an intermediate buffer before writing.
+   *
+   * @param dst The destination address
+   * @param src The source address
+   * @param length the number of bytes to copy
+   * @param explicitMemoryUpdate true if triggered by a memory opcode, false otherwise
+   */
+  public void copyMemory(
+      final long dst, final long src, final long length, final boolean explicitMemoryUpdate) {
+    if (length > 0) {
+      memory.copy(dst, src, length);
+      if (explicitMemoryUpdate) {
+        setUpdatedMemory(dst, memory.getBytes(dst, length));
+      }
+    }
+  }
+
   private void setUpdatedMemory(
       final long offset, final long sourceOffset, final long length, final Bytes value) {
     final long endIndex = sourceOffset + length;

evm/src/main/java/org/hyperledger/besu/evm/operation/MCopyOperation.java

@@ -21,8 +21,6 @@
 import org.hyperledger.besu.evm.frame.MessageFrame;
 import org.hyperledger.besu.evm.gascalculator.GasCalculator;
 
-import org.apache.tuweni.bytes.Bytes;
-
 /** The Memory copy operation. */
 public class MCopyOperation extends AbstractOperation {
 
@@ -46,10 +44,7 @@ public OperationResult execute(final MessageFrame frame, final EVM evm) {
       return new OperationResult(cost, ExceptionalHaltReason.INSUFFICIENT_GAS);
     }
 
-    // read memory copies into a new buffer, no need to copy here.
-    final Bytes callData = frame.readMemory(src, length);
-
-    frame.writeMemory(dst, length, callData, true);
+    frame.copyMemory(dst, src, length, true);
 
     return new OperationResult(cost, null);
   }