topic >You have a helpful error in Intel® ISA Extensions

could not decode some pattern of vgatherdps

mitsunari_s_ — Fri, 14 Sep 2018 05:41:31 GMT

The byte code of `vgatherdps zmm0{k1}, [rax + zmm0]` is 62F27D49920400. But >xed -d 62F27D49920400 >62F27D49920400 >ERROR: GATHER_REGS Could not decode at offset: 0x0 PC: 0x0: [62F27D499204000000000000000000] The reason of this error may be that the index and the destination registers are the same and it results a UD fault. But -d option is not to emutate the byte code but to decode one instruction, so I expect that xed shows the result of disassemble. How about it? verions of xed. >Copyright (C) 2017, Intel Corporation. All rights reserved. >XED version: [8.15.0-6-gb862fe0]

A #UD is not a valid

MarkC_Intel — Mon, 17 Sep 2018 13:10:09 GMT

A #UD is not a valid instruction so there is technically nothing to decode or disassemble here.

FWIW, I did try to give a helpful error indicator for this case.

Thank you. I see.

mitsunari_s_ — Fri, 21 Sep 2018 03:13:24 GMT

Thank you. I see. I would be happy if xed shows a helpful message in the same way that shows ud2 for 0f0b.

UD2 is an instruction, that

MarkC_Intel — Fri, 21 Sep 2018 12:19:26 GMT

UD2 is an instruction, that is different. You have a helpful error message already: "ERROR: GATHER_REGS"

>You have a helpful error

mitsunari_s_ — Fri, 21 Sep 2018 12:48:02 GMT

>You have a helpful error message already: "ERROR: GATHER_REGS"

I see. My understanding was wrong.