[Feature Request] Extension to the instruction flag

[billyauhk]

Is it possible to have an extension to the --instruction flag which also allow us to specify the instruction signature?
Say I want to test --instruction="vsomevector zmm,zmm" directly without going over the xmm and ymm variant.

[kobalicek]

I'm wondering, what is a use-case for this?

[billyauhk]

I am trying to exclude that the long latency of the zmm variant is related to the the preceding instructions of the ymm variant...

"instructions":[
{"inst":"vfmadd231ps xmm, xmm, xmm" ,"lat": 2.96,"rcp": 0.43},
{"inst":"vfmadd231ps ymm, ymm, ymm" ,"lat": 2.96,"rcp": 0.44},
{"inst":"vfmadd231ps zmm, zmm, zmm" ,"lat": 55.17,"rcp": 0.45}
]

[kobalicek]

I think this should be considered a bug - maybe we should run some code before testing anything AVX-512 to heat it up?

[billyauhk]

It is probably not an AVX-512 issue as such situation seems only limited to AVX-512 FMA instructions:
vpmaddubsw xmm, xmm, xmm : Lat: 3.70 Rcp: 0.53
vpmaddubsw ymm, ymm, ymm : Lat: 3.70 Rcp: 0.54
vpmaddubsw zmm, zmm, zmm : Lat: 4.17 Rcp: 0.62