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Re: [PATCH][AArch64][doc] Clarify -msve-vector-bits=128 behaviour


Thanks for doing this.

"Kyrill Tkachov" <kyrylo.tkachov@foss.arm.com> writes:
> @@ -15716,16 +15716,19 @@ an effect when SVE is enabled.
>  
>  GCC supports two forms of SVE code generation: ``vector-length
>  agnostic'' output that works with any size of vector register and
> -``vector-length specific'' output that only works when the vector
> -registers are a particular size.  Replacing @var{bits} with
> -@samp{scalable} selects vector-length agnostic output while
> -replacing it with a number selects vector-length specific output.
> -The possible lengths in the latter case are: 128, 256, 512, 1024
> -and 2048.  @samp{scalable} is the default.
> -
> -At present, @samp{-msve-vector-bits=128} produces the same output
> -as @samp{-msve-vector-bits=scalable}.
> -
> +``vector-length specific'' output that allows GCC to make assumptions
> +about the vector length when it is useful for optimization reasons.
> +The possible values of @samp{bits} are: @samp{scalable}, @samp{128},
> +@samp{256}, @samp{512}, @samp{1024} and @samp{2048}.
> +Specifying @samp{scalable} selects vector-length agnostic
> +output.  At present @samp{-msve-vector-bits=128} also generates vector-length
> +agnostic output.  All other values generate vector-length specific code.
> +The behavior of these values may change in future releases and no value except
> +@samp{scalable} should be relied on for producing code that is portable across
> +different hardware SVE vector lengths.
> +
> +The default is @samp{-msve-vector-bits=scalable} which produces
> +vector-length agnostic code.

Think we should have a comma before "which" in the last sentence.
OK with that change.

Richard


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