Re: [PATCH 0/3] tcg/i386: Improve 8-bit shifts with VGF2P8AFFINEQB

[Paolo Bonzini <pbonzini@redhat.com>]

On 8/27/25 09:26, Richard Henderson wrote:
> On 8/10/25 09:42, Richard Henderson wrote:
>> x86 doesn't directly support 8-bit vector shifts, so we have
>> some 2 to 5 insn expansions.  With VGF2P8AFFINEQB, we can do
>> it in 1 insn, plus a (possibly shared) constant load.
>>
>>
>> r~
>>
>>
>> Richard Henderson (3):
>>    cpuinfo/i386: Detect GFNI as an AVX extension
>>    tcg/i386: Add INDEX_op_x86_vgf2p8affineqb_vec
>>    tcg/i386: Use vgf2p8affineqb for MO_8 vector shifts
>>
>>   host/include/i386/host/cpuinfo.h |  1 +
>>   include/qemu/cpuid.h             |  3 ++
>>   util/cpuinfo-i386.c              |  1 +
>>   tcg/i386/tcg-target-opc.h.inc    |  1 +
>>   tcg/i386/tcg-target.c.inc        | 81 ++++++++++++++++++++++++++++++--
>>   5 files changed, 83 insertions(+), 4 deletions(-)
>>
> 
> Ping.

I don't know the target-independent part of TCG, but arithmetic right 
shift by 7 probably should keep using pcmpgtb?

There's also a typo in patch 1 (s/NF/FN/):

+#ifndef bit_GNFI
+#define bit_GNFI        (1 << 8)
+#endif

Paolo