Displaying 3 results from an estimated 3 matches for "vr256x".
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vr256
2015 Aug 31
2
MCRegisterClass mandatory vs preferred alignment?
...nt,
> dag regList, RegAltNameIndex idx = NoRegAltName>
>
> X86RegisterInfo.td:
>
> def VR256 : RegisterClass<"X86", [v32i8, v16i16, v8i32, v4i64, v8f32, v4f64],
> 256, (sequence "YMM%u", 0, 15)>;
> def VR256X : RegisterClass<"X86", [v32i8, v16i16, v8i32, v4i64, v8f32, v4f64],
> 256, (sequence "YMM%u", 0, 31)>;
>
> Seems to be 256bits/32bytes.
Yeah, don't know how I missed that. :)
>
> I don't know why the alignment was specifie...
2015 Aug 31
3
MCRegisterClass mandatory vs preferred alignment?
Looking around today, it appears that TargetRegisterClass and
MCRegisterClass only includes a single alignment. This is documented as
being the minimum legal alignment, but it appears to often be greater
than this in practice. For instance, on x86 the alignment of %ymm0 is
listed as 32, not 1. Does anyone know why this is?
Additionally, where are these alignments actually defined? I
2017 Jul 28
3
Purpose of various register classes in X86 target
Hello Matthias,
On 28 July 2017 at 04:13, Matthias Braun <mbraun at apple.com> wrote:
> It's not that hard in principle:
> - A register class is a set of registers.
> - Virtual Registers have a register class assigned.
> - If you have register constraints (like x86 8bit operations only work on
> al,ah,etc.) then you have to create a new register class to express that.