import java.util.Random;
import java.util.Arrays;
 
public class test {
  public static void micro(double [] dst, double [] src) {
     for (int i = 0; i < 1024; i++) {
         dst[i] = Math.tanh(src[i]);
     }
  }
  public static void main(String [] args) {
     Random R = new Random(1023);
     double [] res = new double[1024];
     double [] src = new double[1024];
     for (int i = 0; i < 1024; i++) {
         src[i] = 0.5;
     }
     for (int i = 0 ; i < 100000; i++) {
         micro(res, src);
     }
     long t1 = System.currentTimeMillis();
     for (int i = 0 ; i < 100000; i++) {
         micro(res, src);
     }
     long t2 = System.currentTimeMillis();
     System.out.println("[time] " + (t2-t1) + " ms [res] ");
  }
}
GNR>java -XX:+UnlockDiagnosticVMOptions -Xbatch -XX:-TieredCompilation -XX:DisableIntrinsic=_dtanh -cp . test
GNR>### 0.1
GNR>java -XX:+UnlockDiagnosticVMOptions -Xbatch -XX:-TieredCompilation -XX:DisableIntrinsic=_dtanh -cp . test
[time] 1091 ms [res]
GNR>java -XX:+UnlockDiagnosticVMOptions -Xbatch -XX:-TieredCompilation -cp . test
[time] 1562 ms [res]
GNR>
GNR>
GNR>vi test.java
GNR>javac test.java
GNR>### 0.5
GNR>java -XX:+UnlockDiagnosticVMOptions -Xbatch -XX:-TieredCompilation -XX:DisableIntrinsic=_dtanh -cp . test
[time] 1349 ms [res]
GNR>java -XX:+UnlockDiagnosticVMOptions -Xbatch -XX:-TieredCompilation -cp . test
[time] 1547 ms [res]
GNR>


GNR>java --version
openjdk 25-ea 2025-09-16
OpenJDK Runtime Environment (build 25-ea+17-1966)
OpenJDK 64-Bit Server VM (build 25-ea+17-1966, mixed mode, sharing)