8288047: Accelerate Poly1305 on x86_64 using AVX512 instructions

Reviewed-by: sviswanathan, vlivanov

src/java.base/share/classes/sun/security/util/math/IntegerModuloP.java

@@ -153,6 +153,11 @@ public interface IntegerModuloP {
      */
     void asByteArray(byte[] result);
 
+    /**
+     * Break encapsulation, used for IntrinsicCandidate functions
+     */
+    long[] getLimbs();
+
     /**
      * Compute the multiplicative inverse of this field element.
      *

src/java.base/share/classes/sun/security/util/math/intpoly/IntegerPolynomial.java

@@ -626,6 +626,10 @@ public abstract sealed class IntegerPolynomial implements IntegerFieldModuloP
             }
             limbsToByteArray(limbs, result);
         }
+
+        public long[] getLimbs() {
+            return limbs;
+        }
     }
 
     protected class MutableElement extends Element