News:

Masm32 SDK description, downloads and other helpful links
Message to All Guests
NB: Posting URL's See here: Posted URL Change

Main Menu

problem with avx instruction

Started by markallyn, November 02, 2017, 03:00:53 AM

Previous topic - Next topic

aw27

I just tried it, was not expecting it to be so easy, and simply worked on my SandyBridge which does not support AVX2.

sde -- myTest.exe

Siekmanski

Hi Jochen,

vpshufd = 512 bit.
vshufpd = 256 bit.
Creative coders use backward thinking techniques as a strategy.

aw27

Quote from: Siekmanski on November 04, 2017, 11:57:44 PM
Hi Jochen,

vpshufd = 512 bit.
vshufpd = 256 bit.

vpshufd is AVX2 instruction not AVX-512 instruction. AVX-512 added BW, VL, F extensions.

jj2007

I got SDE running, but it seems a bit buggy. Olly stops in the middle of nowhere, etc. However, the simple demo manages to go beyond the "illegal instruction" line when e.g. -skl is specified.

But -slm chokes with SDE-ERROR: Executed instruction not valid for specified chip (SILVERMONT): 0x401201: vmovdqa

Siekmanski

aw27, you are right, vpshufd is avx2 and not a 512 bit instruction.  :icon_redface: I'm awake now.
Creative coders use backward thinking techniques as a strategy.

aw27

Quote from: jj2007 on November 05, 2017, 12:53:19 AM
I got SDE running, but it seems a bit buggy. Olly stops in the middle of nowhere, etc. However, the simple demo manages to go beyond the "illegal instruction" line when e.g. -skl is specified.

But -slm chokes with SDE-ERROR: Executed instruction not valid for specified chip (SILVERMONT): 0x401201: vmovdqa

I have not explored much, but is good to know we have something when we have nothing else.
However, I believe it is not compatible with debuggers, because emulators set the processor into single step mode.

"The Silvermont supports the SSE4.2 instruction set, but not AVX and AVX2" - Agner Fog


jj2007

Quote from: aw27 on November 05, 2017, 01:44:47 AMI believe it is not compatible with debuggers, because emulators set the processor into single step mode.

Once I got it running with Olly, but after a small change somewhere it stopped working. I see your logic but not sure what it means in practice.

aw27

It practice may mean that debugging emulated code may depend on facilities provided by the emulator.
I dont know if you have already read the Help or the Manual. :icon_cool: