A more reproduceable example:
(let [y (float 10)]
(println (str y)))
Yields this:
float y = RT.uncheckedFloatCast(10L);
((IFn)const__42.getRawRoot()).invoke(((IFn)const__43.getRawRoot()).invoke(Float.valueOf(y)));
On Wednesday, February 24, 2016 at 1:15:41 PM UTC-7, Michael du Breuil
wrote:
>
> (let [x (float -199)]
> (.draw batch ^TextureRegion @hud-corner-top-left
> x
> (float -32)))
>
> That's an interop call to libgdx. That generated the disassembly I pasted
> before.
>
> On Wednesday, February 24, 2016 at 5:05:30 AM UTC-7, Nicola Mometto wrote:
>>
>>
>> > On 24 Feb 2016, at 11:58, Michael du Breuil <[email protected]>
>> wrote:
>> >
>> > That just performs a runtime cast to a variable then reference the
>> variable later, which is even worse.
>> >
>> > float x = RT.uncheckedFloatCast(-199L);((SpriteBatch)batch)
>> >
>> .draw((TextureRegion)((IFn)const__5.getRawRoot()).invoke(const__42.getRawRoot()),
>>
>> x,
>> >
>> > RT.uncheckedFloatCast(-32L));
>> >
>>
>>
>> No it doesn't.
>>
>> having
>>
>> (ns test)
>>
>> (definterface Foo
>> (x [^float y]))
>>
>> (let [a (float 1)]
>> (defn y [b]
>> (.x ^Foo b a)))
>>
>> This is the disassemble of y's invoke method:
>>
>> public java.lang.Object invoke(java.lang.Object);
>> Code:
>> 0: aload_1
>> 1: aconst_null
>> 2: astore_1
>> 3: checkcast #18 // class test/Foo
>> 6: aload_0
>> 7: getfield #14 // Field a:F
>> 10: invokeinterface #22, 2 // InterfaceMethod
>> test/Foo.x:(F)Ljava/lang/Object;
>> 15: areturn
>>
>> No float cast involved there. The primitive float is closed over and used
>> directly.
>>
>> > I definitely expected the compiler to pay attention to it, although I
>> also discovered at the same time that the compilier doesn't actually
>> resolve expressions like (+ (* 2 4) 1) to just be 9 at compile time either,
>> even though all the values were constants. Both of these are a problem
>> because they are inside the hot loop of the program. (There are some
>> constant math expressions that are only expressions as it is easier to
>> read/change ^:const named things then to just put one resultant number.
>> >
>> > Is it worth opening a Jira issue for resolving either or both of these
>> at compile time? I looked a briefly at the definition for (float ) but I'm
>> not at all familiar with how the byte code is generated and how to actually
>> replace that with what I'm looking for.
>>
>> Sure, although I don't think doing this kind of constant folding this is
>> going to be a priority.
>>
>> >
>> > On Wednesday, February 24, 2016 at 3:58:46 AM UTC-7, Nicola Mometto
>> wrote:
>> > Those are runtime casts, this is the expected behaviour (although one
>> could argue that clojure should be able to optimize them away at compile
>> time).
>> >
>> > If you want to avoid the runtime casting, you can do something like
>> this:
>> >
>> > (let [x (float 123)]
>> > (defn y [..]
>> > (.foo bar x)))
>> >
>> >
>> > > On 24 Feb 2016, at 10:53, Michael du Breuil <[email protected]>
>> wrote:
>> > >
>> > > The following (this is interop with libgdx if anyone is curious,
>> hud-corner-top-left is a delayed TextureRegion
>> > >
>> > > (.draw batch ^TextureRegion @hud-corner-top-left
>> > > (float -199)
>> > > (float -32))
>> > >
>> > > Which yields the following:
>> > >
>> .draw((TextureRegion)((IFn)const__5.getRawRoot()).invoke(const__41.getRawRoot()),
>>
>>
>> > > RT.uncheckedFloatCast(-199L),
>> > > RT.uncheckedFloatCast(-32L));null;((SpriteBatch)batch)
>> > >
>> > > Unless I'm missing something on how to interpret bytecode :) I can
>> post more source if you want but that is one interop call and its generated
>> code, the rest will look the same.
>> > >
>> > > On Wednesday, February 24, 2016 at 3:44:11 AM UTC-7, Nicola Mometto
>> wrote:
>> > > Can you post the code?
>> > >
>> > > > On 24 Feb 2016, at 10:26, Michael du Breuil <
>> [email protected]> wrote:
>> > > >
>> > > > I have some interop code that I have carefully specified all the
>> arguments to be in the correct type (IE the function signature takes 3
>> floats, so I cast everything to float so that I can avoid reflection). What
>> I'm surprised by is compile time constants such as (float -173) or (float
>> 8.5) are not saved as the correct primitive type, using jd-gui I see that
>> these were actually turned into RT.uncheckedFloatCast(-173L), and
>> RT.uncheckedFloatCast(8.5D), respectively. Why isn't this just saved as a
>> the correct primitive directly in the generated bytecode? This is with
>> clojure 1.8.0
>> > > >
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