Any relationship to CLJ-701, other than similar symptoms?
http://dev.clojure.org/jira/browse/CLJ-701
Andy
On Nov 20, 2012, at 9:15 AM, Christophe Grand wrote:
> Hi,
>
> It looks like, because of the recur, the compiler fails to notice that if
> returns a primitive.
> As far as I understand in Compiler.java, RecurExpr does not implement
> MaybePrimitiveExpr and thus causes on canEmitPrimitive the surrounding IfExpr
> to return false.
>
> Someone to confirm this analysis?
>
>
> On Tue, Nov 20, 2012 at 4:34 PM, Gunnar Völkel
> <gunnar.voel...@googlemail.com> wrote:
> I have written a primitive function for exponentiation with integers as power
> using the multiply-and-square algorithm.
> For performance reasons I used primitive type hints for the arguments and the
> return value.
> Profiling the whole application I noticed that there are a lot of
> java.lang.Double/valueOf calls.
> Looking at the bytecode I see that in Clojure 1.3 as well as in Clojure 1.4
> the result value gets boxed and unboxed like
> Double.valueOf(result).doubleValue().
>
> Am I doing something wrong? Is there a serious bug related to the support of
> primitive functions?
>
> The source code:
>
> (defn first-bit?
> {:inline (fn [n] `(== 1 (clojure.lang.Numbers/and ~n, 1)) )}
> [^long n]
> (== 1 (clojure.lang.Numbers/and n, 1)))
>
> (defn exp-int
> ^double [^double x, ^long c]
> (loop [result 1.0, factor x, c c]
> (if (> c 0)
> (recur
> (if (first-bit? c)
> (* result factor)
> result),
> (* factor factor),
> (bit-shift-right c 1))
> result)))
>
> Last lines of the Java bytecode of `exp-int`:
> 59 dload 5; /* result */
> 61 invokestatic 40; /* java.lang.Double java.lang.Double.valueOf(double
> c) */
> 64 checkcast 85; /* java.lang.Number */
> 67 invokevirtual 89; /* double doubleValue() */
> 70 dreturn;
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