[PATCH][AVX512] Add class to group common template arguments related to vector type

[Robert Khasanov]

Hi Adam,

In addition to Elena's comment, I suggest to add separate mask register
classes, e.g. KRC and KRCWM. Mask and cmp instructions writes to all mask
registers including k0.


2014-08-18 11:31 GMT+04:00 Demikhovsky, Elena <elena.demikhovsky at intel.com>:

> Hi Adam,
>
> Some things that I see:
>
> 1) I suggest to rename EltNum to NumOfElts
>
> 2)
> +  // Corresponding write-mask register class.
> +  RegisterClass KRC = !cast<RegisterClass>("VK" # EltNum # "WM");
> +
> +  // The GPR register class that can hold the write mask.
> +  RegisterClass MRC = !cast<RegisterClass>("GR" # EltNum);
>
> VK2 is possible, GR2 is not.
>
> 2) I don't think that default rc is good. Let everybody specify register
> class explicitly.
> +class X86VectorVTInfo<int EltNum, ValueType EltVT, RegisterClass rc =
> VR512,
> +                      string suffix = ""> {
>
> 3) Let's assume that I'm building
> def v16f32_info :  X86VectorVTInfo<16, f32, VR512, "ps">
> how FloatVT will look like?
> Do we need IntVT for completeness?
>
> 4) I suggest to add broadcast string {1toX} to the info.
>
>
>
> -  Elena
>
>
> -----Original Message-----
> From: Adam Nemet [mailto:anemet at apple.com]
> Sent: Monday, August 18, 2014 09:17
> To: Demikhovsky, Elena; Khasanov, Robert
> Cc: llvm-commits
> Subject: [PATCH][AVX512] Add class to group common template arguments
> related to vector type
>
> Hi,
>
> We discussed the issue of generality vs. readability of the AVX512 classes
> recently.  I proposed this approach to try to hide and centralize the
> mappings we commonly perform based on the vector type.  A new class
> X86VectorVTInfo captures these.
>
> The idea is to pass an instance of this class to classes/multiclasses
> instead of the corresponding ValueType.  Then the class/multiclass can use
> its field for things that derive from the type rather than passing all
> those as separate arguments.
>
> I modified avx512_valign to demonstrate this new approach.  As you can see
> instead of 7 related template parameters we now have one.  The downside is
> that we have to refer to fields for the derived values.  I named the
> argument '_' in order to make this as invisible as possible.  Please let me
> know if you absolutely hate this.  (Also once we allow local
> initializations in multiclasses we can recover the original version by
> assigning the fields to local variables.)
>
> Another possible use-case for this class is to directly map things, e.g.:
>
>   RegisterClass KRC = X86VectorVTInfo<32, i16>.KRC
>
> Please let me know if it looks good.
>
> Adam
>
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