Re: [Qemu-devel] [PATCH v6 15/16] tcg/ppc: Update vector support to v2.07

[Richard Henderson <richard.henderson@linaro.org>]

On 7/1/19 5:57 AM, Aleksandar Markovic wrote:
> 
> On Jun 30, 2019 5:12 PM, "Richard Henderson" <richard.henderson@linaro.org
> <mailto:richard.henderson@linaro.org>> wrote:
>>
>> On 6/30/19 3:37 PM, Aleksandar Markovic wrote:
>> >>  bool have_isa_2_06;
>> >>  bool have_isa_2_06_vsx;
>> >> +bool have_isa_2_07_vsx;
>> >
>> > Does this flag indicate support for PowerISA 2.07 or VSX?
>>
>> VSX & 2.07,
>>
>> >> +    if (hwcap2 & PPC_FEATURE2_ARCH_2_07) {
>> >> +        if (hwcap & PPC_FEATURE_HAS_VSX) {
>> >> +            have_isa_2_07_vsx = true;
>> >> +        }
>> >> +    }
>>
>> Like so.
>>
>> While it would have been possible to have one single have_isa_vsx, we would
>> then also have to check a second flag to see which revision.  Therefore I
>> created these composite flags so that we only have to check one.
>>
> 
> Yes, but, in this patch, for example, among other things, the support for
> doubleword integer max/min vector operation is implemented. Why is the
> existence of that support dependant on VSX (PPC_FEATURE_HAS_VSX)?

Because otherwise the instruction doesn't exist?


r~