Re: [PATCH v3 0/2] x86: insn template CPU specifier processing

[Jan Beulich <jbeulich@suse.com>]

On 08.11.2023 12:43, Cui, Lili wrote:
>> Subject: [PATCH v3 0/2] x86: insn template CPU specifier processing
>>
>> This continues to be in particular in preparation for APX.
>>
>> 1: Cpu64 handling improvements
>> 2: split insn templates' CPU field
>>
>> While only noticeable in generated files, this goes on top of "x86:
>> Intel Core processors do not support CMPXCHG16B" [1]. (Guess how I noticed
>> that other issue.)
>>
>> The 1st patch is new in v3, and it being placed first allows what is now the 2nd
>> patch here to be shrunk some.
>>
>> Jan
>>
>> [1] https://sourceware.org/pipermail/binutils/2023-November/130372.html
> 
> Hi Jan,
> 
> I adapted the apx patch based on these 3 patches and they work fine, but I still have two issues. They are all in install_template.
> 
> 1. We need to clear i.tm.opcode_modifier.evex = 0 or i.tm.opcode_modifier.vex = 0 for all merged insn, I found that output_insn also needs to use i.tm.opcode_modifier.evex. We need to add the cpu id here for each new merge (VEX and EVEX), which looks a bit ugly. Now I just add AMX for it.
> 
> 
>      if ((maybe_cpu (t, CpuAVX) || maybe_cpu (t, CpuAVX2) || maybe_cpu (t, CpuAMX_TILE)
>            || maybe_cpu (t, CpuFMA))
>           && (maybe_cpu (t, CpuAVX512F) || maybe_cpu (t, CpuAVX512VL) || maybe_cpu (t, CpuAPX_F)))

I specifically mentioned already that this may want tidying as the set
grows. We can do that up front if you're concerned, or afterwards.

I don't, however, understand how this is connected to you saying "I
found that output_insn also needs to use i.tm.opcode_modifier.evex".

> 2.  The assertion below blocks AMX insns and I need to remove it.
>               else
>                 {
>                   //gas_assert (!i.tm.cpu.bitfield.isa);
>                   i.tm.cpu.bitfield.isa = i.tm.cpu_any.bitfield.isa;
>                 }

I had asked about this already in reply to one of the patches, also
pointing out that removing the assertion is problematic. By you not
explaining what the problem is, I still can't figure how this is
getting in the way of AMX. Specifically in that case, what are the
values of both fields upon entry into this block?

Jan