(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]
> <javascript:>> 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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