jgpc42 · August 18, 2017 02:35
diff --git a/hashcode-bench.clj b/hashcode-bench.clj
 ;; $ java -cp ~/.lein/self-installs/leiningen-2.7.1-standalone.jar clojure.main hashcode-bench.clj


 (println "Java" (System/getProperty "java.version"))
 (println "Clojure" (apply str ((juxt :major (constantly \.) :minor) *clojure-version*)))
 ;; => Java 1.8.0_131
 ;; => Clojure 1.8

 (require '[cemerick.pomegranate :as pom])

 (pom/add-dependencies
 :coordinates '[[criterium "0.4.4"]
                [insn "0.1.0"]]
 :repositories {"clojars" "https://clojars.org/repo"})

 (require '[criterium.core :as crit]
         '[insn.clojure :as bc])
 (import [java.util Arrays])

 (set! *warn-on-reflection* true)
 (set! *unchecked-math* :warn-on-boxed)


 (bc/defn bytecode ^long [arr]
  [[:aload 1] [:ifnull :L/NULL]                ;; if arr == null then goto NULL
   [:aload 1] [:checkcast [:int]] [:astore 1]  ;; arr = (int[]) arr
   [:aload 1] [:arraylength]      [:istore 2]  ;; len = arr.length
   [:ldc 0]   [:istore 3]                      ;; i = 0
   [:ldc 1]   [:istore 4]                      ;; h = 1
   [:mark :L/LOOP]
   [:iload 2]  [:iload 3] [:if-icmpeq :L/RET]  ;; if len == i then goto RET
   [:ldc 31]   [:iload 4] [:imul]              ;; push h * 31
   [:aload 1]  [:iload 3] [:iaload]            ;; push arr[i]
   [:iadd]     [:istore 4]                     ;; add pushed values, store into h
   [:iinc 3 1] [:goto :L/LOOP]                 ;; i++, goto LOOP
   [:mark :L/RET]
   [:iload 4] [:i2l] [:lreturn]                ;; return h as long
   [:mark :L/NULL]
   [:ldc2 0] [:lreturn]])                      ;; return 0L

 (defn clojure ^long [^ints arr]
  (if (nil? arr)
    0
    (let [len (long (alength arr))]
      (loop [i 0, h 1]
        (if (< i len)
          (recur (unchecked-inc i)
                 (unchecked-add-int
                  (unchecked-multiply-int
                   (unchecked-int h) (unchecked-int 31))
                  (aget arr (unchecked-int i))))
          h)))))

 (defn java ^long [^ints arr]
  (Arrays/hashCode arr))


 (let [array (int-array (range 100))
      exp (java array)]
  (crit/bench (assert (== exp (bytecode array)))) ;; => Execution time mean : 89.884445 ns
  (crit/bench (assert (== exp (clojure array))))  ;; => Execution time mean : 125.551577 ns
  (crit/bench (assert (== exp (java array)))))    ;; => Execution time mean : 89.781852 ns
	;; $ java -cp ~/.lein/self-installs/leiningen-2.7.1-standalone.jar clojure.main hashcode-bench.clj


	(println "Java" (System/getProperty "java.version"))
	(println "Clojure" (apply str ((juxt :major (constantly \.) :minor) clojure-version)))
	;; => Java 1.8.0_131
	;; => Clojure 1.8

	(require '[cemerick.pomegranate :as pom])

	(pom/add-dependencies
	:coordinates '[[criterium "0.4.4"]
	[insn "0.1.0"]]
	:repositories {"clojars" "https://clojars.org/repo"})

	(require '[criterium.core :as crit]
	'[insn.clojure :as bc])
	(import [java.util Arrays])

	(set! warn-on-reflection true)
	(set! unchecked-math :warn-on-boxed)


	(bc/defn bytecode ^long [arr]
	[[:aload 1] [:ifnull :L/NULL] ;; if arr == null then goto NULL
	[:aload 1] [:checkcast [:int]] [:astore 1] ;; arr = (int[]) arr
	[:aload 1] [:arraylength] [:istore 2] ;; len = arr.length
	[:ldc 0] [:istore 3] ;; i = 0
	[:ldc 1] [:istore 4] ;; h = 1
	[:mark :L/LOOP]
	[:iload 2] [:iload 3] [:if-icmpeq :L/RET] ;; if len == i then goto RET
	[:ldc 31] [:iload 4] [:imul] ;; push h * 31
	[:aload 1] [:iload 3] [:iaload] ;; push arr[i]
	[:iadd] [:istore 4] ;; add pushed values, store into h
	[:iinc 3 1] [:goto :L/LOOP] ;; i++, goto LOOP
	[:mark :L/RET]
	[:iload 4] [:i2l] [:lreturn] ;; return h as long
	[:mark :L/NULL]
	[:ldc2 0] [:lreturn]]) ;; return 0L

	(defn clojure ^long [^ints arr]
	(if (nil? arr)
	0
	(let [len (long (alength arr))]
	(loop [i 0, h 1]
	(if (< i len)
	(recur (unchecked-inc i)
	(unchecked-add-int
	(unchecked-multiply-int
	(unchecked-int h) (unchecked-int 31))
	(aget arr (unchecked-int i))))
	h)))))

	(defn java ^long [^ints arr]
	(Arrays/hashCode arr))


	(let [array (int-array (range 100))
	exp (java array)]
	(crit/bench (assert (== exp (bytecode array)))) ;; => Execution time mean : 89.884445 ns
	(crit/bench (assert (== exp (clojure array)))) ;; => Execution time mean : 125.551577 ns
	(crit/bench (assert (== exp (java array))))) ;; => Execution time mean : 89.781852 ns