an exploration of int casting and long reads in clojure

intcasts.clj

(require '[clj-java-decompiler.core :refer [decompile disassemble]])
(require '[primitive-math])
(set! *warn-on-reflection* true)
(set! *unchecked-math* :warn-on-boxed)

(decompile
 (fn []
   (let [xs (int-array 10)
         idx 0]
     (aset xs idx 0))))

;; // Decompiling class: user$fn_line_2__215
;; import clojure.lang.*;

;; public final class user$fn_line_2__215 extends AFunction
;; {
;;  public static final Object const__1;

;;  public static Object invokeStatic() {
;;                                       final Object xs = Numbers.int_array(user$fn_line_2__215.const__1);
;;                                       final long idx = 0L;
;;                                       return RT.aset((int[])xs, RT.intCast(idx), RT.intCast(0L));
;;                                       }

;;  @Override
;;  public Object invoke() {
;;                          return invokeStatic();
;;                          }

;;  static {
;;          const__1 = 10L;
;;          }
;;  }

(decompile
 (fn []
   (let [xs (int-array 10)]
     (aset xs 0 0))))

;; // Decompiling class: user$fn_line_2__225
;; import clojure.lang.*;

;; public final class user$fn_line_2__225 extends AFunction
;; {
;;  public static final Object const__1;

;;  public static Object invokeStatic() {
;;                                       final Object xs = Numbers.int_array(user$fn_line_2__225.const__1);
;;                                       return RT.aset((int[])xs, (int)0L, RT.uncheckedIntCast(0L));
;;                                       }

;;  @Override
;;  public Object invoke() {
;;                          return invokeStatic();
;;                          }

;;  static {
;;          const__1 = 10L;
;;          }
;;  }

(disassemble
 (fn []
   (let [xs (int-array 10)]
     (aset xs 0 0))))

;; // Decompiling class: user$fn_line_2__235
;; class user$fn_line_2__235
;;     Minor version: 0
;;     Major version: 52
;;     Flags: PUBLIC, FINAL, SUPER

;;     public static final java.lang.Object const__1;
;;         Flags: PUBLIC, STATIC, FINAL

;;     public void <init>();
;;         Flags: PUBLIC
;;         Code:
;;                   linenumber      1
;;                0: aload_0
;;                1: invokespecial   clojure/lang/AFunction.<init>:()V
;;                4: return

;;     public static java.lang.Object invokeStatic();
;;         Flags: PUBLIC, STATIC
;;         Code:
;;                   linenumber      1
;;                0: getstatic       user$fn_line_2__235.const__1:Ljava/lang/Object;
;;                   linenumber      1
;;                3: invokestatic    clojure/lang/Numbers.int_array:(Ljava/lang/Object;)[I
;;                6: astore_0        /* xs */
;;                7: aload_0         /* xs */
;;                8: checkcast       [I
;;               11: lconst_0
;;                   linenumber      1
;;               12: l2i
;;               13: lconst_0
;;               14: invokestatic    clojure/lang/RT.uncheckedIntCast:(J)I
;;                   linenumber      1
;;               17: invokestatic    clojure/lang/RT.aset:([III)I
;;               20: invokestatic    java/lang/Integer.valueOf:(I)Ljava/lang/Integer;
;;               23: areturn

;;     public java.lang.Object invoke();
;;         Flags: PUBLIC
;;         Code:
;;                   linenumber      1
;;                0: invokestatic    user$fn_line_2__235.invokeStatic:()Ljava/lang/Object;
;;                3: areturn

;;     static {};
;;         Flags: PUBLIC, STATIC
;;         Code:
;;                   linenumber      1
;;                0: ldc2_w          10
;;                3: invokestatic    java/lang/Long.valueOf:(J)Ljava/lang/Long;
;;                6: putstatic       user$fn_line_2__235.const__1:Ljava/lang/Object;
;;                9: return

;; nil

(decompile
 (fn []
   (let [arr (int-array 10)
         l   (alength   arr)]
     (loop  [idx (int 0)
             acc (int 0)]
       (if (< idx  l)
         (do
           (recur (unchecked-inc idx)
                  (unchecked-inc acc)))
         acc)))))

// Decompiling class: user$fn_line_2__256
import clojure.lang.*;

public final class user$fn_line_2__256 extends AFunction
{
 public static final Object const__1;

 public static Object invokeStatic() {
                                      final Object arr = Numbers.int_array(user$fn_line_2__256.const__1);
                                      final int l = ((int[])arr).length;
                                      long idx = (int)0L;
                                      long acc = (int)0L;
                                      while (idx < l) {
                                                       final long n = idx + 1L;
                                                       ++acc;
                                                       idx = n;
                                                       }
                                      return Numbers.num(acc);
                                      }

 @Override
 public Object invoke() {
                         return invokeStatic();
                         }

 static {
         const__1 = 10L;
         }
 }

(disassemble
 (fn []
   (let [arr (int-array 10)
         l   (alength   arr)]
     (loop  [idx (int 0)
             acc (int 0)]
       (if (< idx  l)
         (do
           (recur (unchecked-inc idx)
                  (unchecked-inc acc)))
         acc)))))


// Decompiling class: user$fn_line_2__260
class user$fn_line_2__260
    Minor version: 0
    Major version: 52
    Flags: PUBLIC, FINAL, SUPER

    public static final java.lang.Object const__1;
        Flags: PUBLIC, STATIC, FINAL

    public void <init>();
        Flags: PUBLIC
        Code:
                  linenumber      1
               0: aload_0
               1: invokespecial   clojure/lang/AFunction.<init>:()V
               4: return

    public static java.lang.Object invokeStatic();
        Flags: PUBLIC, STATIC
        Code:
                  linenumber      1
               0: getstatic       user$fn_line_2__260.const__1:Ljava/lang/Object;
                  linenumber      1
               3: invokestatic    clojure/lang/Numbers.int_array:(Ljava/lang/Object;)[I
               6: astore_0        /* arr */
               7: aload_0         /* arr */
               8: checkcast       [I
                  linenumber      1
              11: arraylength
              12: istore_1        /* l */
              13: lconst_0
                  linenumber      1
              14: l2i
                  linenumber      0
              15: i2l
              16: lstore_2        /* idx */
              17: lconst_0
                  linenumber      1
              18: l2i
                  linenumber      0
              19: i2l
              20: lstore          acc
                  linenumber      1
              22: lload_2         /* idx */
              23: iload_1         /* l */
              24: i2l
              25: lcmp
              26: ifge            46
              29: lload_2         /* idx */
                  linenumber      1
              30: lconst_1
              31: ladd
              32: lload           acc
                  linenumber      1
              34: lconst_1
              35: ladd
              36: lstore          acc
              38: lstore_2        /* idx */
              39: goto            22
              42: nop
              43: nop
              44: athrow
              45: athrow
              46: lload           acc
              48: invokestatic    clojure/lang/Numbers.num:(J)Ljava/lang/Number;
              51: areturn
        StackMapTable: 00 04 FF 00 16 00 04 07 00 17 01 04 04 00 00 FF 00 13 00 00 00 01 07 00 23 42 07 00 23 FF 00 00 00 04 07 00 17 01 04 04 00 00

    public java.lang.Object invoke();
        Flags: PUBLIC
        Code:
                  linenumber      1
               0: invokestatic    user$fn_line_2__260.invokeStatic:()Ljava/lang/Object;
               3: areturn

    static {};
        Flags: PUBLIC, STATIC
        Code:
                  linenumber      1
               0: ldc2_w          10
               3: invokestatic    java/lang/Long.valueOf:(J)Ljava/lang/Long;
               6: putstatic       user$fn_line_2__260.const__1:Ljava/lang/Object;
               9: return



;;Primitive math doesn't save us.
(decompile
 (fn []
   (let [arr (int-array 10)
         l   (alength   arr)]
     (loop  [idx (int 0)
             acc (int 0)]
       (if (< idx  l)
         (do
           (recur (primitive-math/inc idx)
                  (primitive-math/inc acc)))
         acc)))))

import clojure.lang.*;
import primitive_math.*;

public final class user$fn_line_2__553 extends AFunction
{
 public static final Object const__1;

 public static Object invokeStatic() {
   final Object arr = Numbers.int_array(user$fn_line_2__553.const__1);
   final int l = ((int[])arr).length;
   long idx = (int)0L;
   long acc = (int)0L;
   while (idx < l) {
                    final long inc = Primitives.inc(idx);
                    acc = Primitives.inc(acc);
                    idx = inc;
                    }
   return Numbers.num(acc);
   }

 @Override
 public Object invoke() {
                         return invokeStatic();
                         }

 static {
         const__1 = 10L;
         }
 }