http://d.puremagic.com/issues/show_bug.cgi?id=7413

           Summary: Vector literals don't work
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: turkeyman@gmail.com


--- Comment #0 from Manu <turkeyman@gmail.com> 2012-01-31 10:54:16 PST ---
Vector literals in the form:
  float4 v = [1,2,3,4];

still don't appear to work...

Literal should be allocated & aligned, ideally PC relative, right next to the
function (at least possible in x64).
Additionally, assigning literals '0' or [0,0,0,0] should generate the
appropriate xor opcode.

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--- Comment #1 from Manu <turkeyman@gmail.com> 2012-01-31 17:27:58 PST ---
There's a bunch of other handy immediates too:

-1 = cmpeq(anyReg, anyReg)
 - 1 opcode, always better than a load

1,3,7,15,etc can be generated by shifting -1 right by some immediate
 - 2 opcodes, pc-relative load might be better, depends on pipeline

2,4,8,16,etc can be generated by shifting 1 left
 - 3 opcodes, pc-relative load is probably better, depends on pipeline

1.0f (0x3f800000) can be generated by shifting -1 right 25 bits, then left 23
bits
 - 3 opcodes, pc-relative load is probably better, depends on pipeline

etc...

Just something to be aware of

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--- Comment #2 from Manu <turkeyman@gmail.com> 2012-03-01 13:53:30 PST ---
I'd like to see this promoted above the priority of other SIMD tasks. This is holding me up. I can't write unit tests without literals.

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Sean Cavanaugh <WorksOnMyMachine@gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |WorksOnMyMachine@gmail.com


--- Comment #3 from Sean Cavanaugh <WorksOnMyMachine@gmail.com> 2012-03-01 14:16:27 PST ---
Hex float constants don't seem to be expressive enough to handle all 2^32 or 2^64 bit patterns for float or double (nan, exponent masks, mantissa only masks etc).

This is a problem for defining more exotic data while maintining the correct 'type' for the constant (float4 instead of an int4, double2 instead of long2 etc)

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Manu <turkeyman@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |blocker


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--- Comment #4 from Manu <turkeyman@gmail.com> 2012-03-11 12:11:46 PDT ---
Walter had planned to use standard array literal syntax as far as I knew:
float4 v = [1.0, 2.0, 3.0, 4.0];
shourt8 sv = [1,2,3,4,5,6,7,8];

How he intended to disambiguate the type, I have no idea.
Vector literals must be 128bit aligned, so the compiler needs to recognise
they're being assigned to a vector and treat them special.
It sounds better to have an explicit literal syntax to me.

I guess there's always this option, but it's horrible:
int4 v = __vector([1,2,3,4]);

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SomeDude <lovelydear@mailmetrash.com> changed:

           What    |Removed                     |Added
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                 CC|                            |lovelydear@mailmetrash.com


--- Comment #5 from SomeDude <lovelydear@mailmetrash.com> 2012-04-21 05:35:44 PDT ---
See also issue 7414

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--- Comment #7 from Manu <turkeyman@gmail.com> 2012-05-01 07:44:29 PDT ---
(In reply to comment #6)
> Note that for the moment you can do things like:
> 
>     int[4] o = [1,2,3,4];
>     int4 v1;
>     v1.array = o;

Indeed, but that's not something you can just type conveniently in user code. I wrap that in a little constructor function, which is fine for now.

Proper literals are blocking std.simd though (which I'd really like to finish). I don't think it's fair to say it's done without literals, and unit tests which need an awful lot of literals.

If it's not likely to make the short list though, I'll finish it off with some sort of constructor function in the mean time.

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--- Comment #8 from Walter Bright <bugzilla@digitalmars.com> 2012-05-01 10:40:39 PDT ---
I'm looking in to it, I just thought that the workaround could keep you going for the moment.

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--- Comment #9 from Manu <turkeyman@gmail.com> 2012-05-01 10:51:12 PDT ---
(In reply to comment #8)
> I'm looking in to it, I just thought that the workaround could keep you going for the moment.

Yeah, no worries. Already on it. Cheers :)

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