CLJS-2336: Call alength once in areduce and amap

Author: mfikes

benchmark/cljs/benchmark_runner.cljs

@@ -24,6 +24,13 @@
 (simple-benchmark [coll arr] (array-reduce coll + 0) 1)
 (simple-benchmark [coll arr] (array-reduce coll sum 0) 1)
 
+(println ";; areduce")
+(def x (atom 0))
+(simple-benchmark [arr (to-array (range 1000000))] (reset! x (areduce arr i ret 0 (+ ret (aget arr i)))) 1)
+
+(println ";; amap")
+(simple-benchmark [arr (to-array (range 1000000))] (amap arr i ret (* 10 (aget arr i))) 1)
+
 (println ";;; instance?")
 ;; WARNING: will get compiled away under advanced
 (simple-benchmark [coll []] (instance? PersistentVector coll) 1000000)

src/main/clojure/cljs/core.cljc

@@ -2576,9 +2576,10 @@
   array ret."
   [a idx ret expr]
   `(let [a# ~a
+         l# (alength a#)
          ~ret (cljs.core/aclone a#)]
      (loop  [~idx 0]
-       (if (< ~idx  (alength a#))
+       (if (< ~idx l#)
          (do
            (aset ~ret ~idx ~expr)
            (recur (inc ~idx)))
@@ -2589,9 +2590,10 @@
   and return value named ret, initialized to init, setting ret to the
   evaluation of expr at each step, returning ret."
   [a idx ret init expr]
-  `(let [a# ~a]
+  `(let [a# ~a
+         l# (alength a#)]
      (loop  [~idx 0 ~ret ~init]
-       (if (< ~idx  (alength a#))
+       (if (< ~idx l#)
          (recur (inc ~idx) ~expr)
          ~ret))))