RE: Flat initializer list for union of unnamed struct fields
- From: William Adams <william_a_adams@xxxxxxx>
- To: "luajit@xxxxxxxxxxxxx" <luajit@xxxxxxxxxxxxx>
- Date: Tue, 9 Sep 2014 14:33:12 +0000
I did a thing on swizzling in the Khronos APIs:
http://williamaadams.wordpress.com/2013/04/03/dynamically-swizzled-type-equivalent-goodness/
Not highly performant code (uses table lookups), but it might be interesting to
look at.
-- William
===============================
- Shaping clay is easier than digging it out of the ground.
> Date: Mon, 8 Sep 2014 23:48:02 -0400
> From: peter@xxxxxxxxxxx
> To: luajit@xxxxxxxxxxxxx
> Subject: Re: Flat initializer list for union of unnamed struct fields
>
> On Tue, Sep 09, 2014 at 01:46:25AM +0200, Mike Pall wrote:
> > Initialization of nested aggregates is not compiled. This is far
> > from trivial in the general case. You can send a patch, if you
> > really want to dive into this (function crec_alloc).
>
> Please see the attached patch against LuaJIT 2.1.
>
> It is a first attempt, but the test case already compiles:
>
> [TRACE 1 union.lua:19 loop]
> [TRACE --- union.lua:12 -- NYI: return to lower frame at union.lua:24]
> [TRACE 2 union.lua:23 loop]
>
> Could you give hints on how to improve the patch?
>
> > IMHO it makes sense to enforce a common notation. Otherwise people
> > will have a hard time to understand each other's modules. A simple
> > struct is much easier on the compiler, too.
>
> The OpenCL C specification permits both (and more) notations for
> accessing vector components in device code, so for consistency the
> host code should support both notations, too. The choice of notation
> depends on how a vector type is used: x,y,z is suited for physical
> vectors, s0,s1,s2,…,sA,…,sF for any aggregates up to 16 components.
>
> To my surprise a plain struct versus a union with nested struct
> perform equally well with the attached patch. The code transforms
> and averages the velocities of 10⁵ solvent particles to obtain a
> flow field. The allocation sinking in LuaJIT 2.1 is impressive.
>
> Thanks,
> Peter
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