Intel® ISA Extensions
Use hardware-based isolation and memory encryption to provide more code protection in your solutions.

Encoding phsubsw with VEX.256

PFaut2
Beginner
305 Views

Hi,

I don't understand how to encode PHSUBSW with VEX.256. According to the documentation, VEX.L must be 0, otherwise the instruction will #UD. I thought we must use VEX.L = 1 to force the VEX.256.

Thanks

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1 Reply
MarkC_Intel
Moderator
305 Views

Hi. Thanks. Yeah that "VEX.L must be zero" thing is left over from before we introduced AVX2 which added the 256b encoding for this instruction. I'll ask our doc team to fix this (and possibly others that might have similar origin).

 

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