Introduction to Intel Advanced Vector Extensions

Introduction to Intel Advanced Vector Extensions

Portrait de bronxzv
bronxzv
mar, 31/01/2012 - 05:27

I just read this article:

http://software.intel.com/en-us/articles/introduction-to-intel-advanced-vector-extensions/

it's a fairly good introduction to AVX though in the "Instruction Set Overview"the author states that "As a result, the VEX instructions can only be used when running in 64-bit mode." I know from first hand experience that this is wrong since my own AVX coderunfine in32-bit mode on a Sandy Bridge CPU. I'll suggest to fix this error in the article since newcomers to AVX may be misled by this.

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Portrait de Max Locktyukhin (Intel)
Max Locktyukhin (Intel)
jeu, 23/02/2012 - 03:18

nice catch, wrong statement for sure, we will fix it,
thanks! ... author was close in understanding of LDS/LES opcodes re-use for VEX
prefix, but what happens in 32-bit is that VEX prefix, although still using
LDS/LES opcodes, always ends up in unsupported forms of these instructions (those
with memory operands), thanks to bit-complement encoding of some fields, hence everything
is backwards compatible in 32-bit mode too

-Max

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