Hi,
The main reason for this is to get some understanding about POPCNT (SSE4.2, optional). These SSE4 instructions are split in half. The second iteration has only 7 instructions, but is it actually 7?

When its optional and replaces JMPE, then what happens if its not present - should all future code to run on any processor have runtime detection of POPCNT presence? Then you need to replace every occurrence of JMPE respectively This is NOT possible!

And FASM should incorporate that

Thoughts, answers......questions?

There's a difference: although JMPE employs 0FB8, POPCNT is F30FB8. Wikipedia seems to be wrong here.

Hmm and we all rest assured! Thanks for clearing this...

Personally I wouldn't worry about JMPE/POPCNT overlay unless you know your app is going to run on itanium...

But since you ought to check for very late-and-breaking-news instructions such as POPCNT and choose your code paths accordingly, I don't think it'd ever end up being a problem - Itanium CPUs obviously wouldn't support POPCNT

Why not?

Because of the opcode overlaying issue... now, they might support it in native mode, but probably not for emulation. (And x86 hardware emulation on itanium is slower than software emulation, oh well).

Is intel still working on Itanium btw., or have they stopped after Itanium-2?

Since POPCNT uses F3 "prefix", I don't think it really overlays JMPE, as I wrote above. Colision with some older code, which would encode JMPE as F30FB8, is very unlikely.

I think its pretty clear now - its one of those errors where people think that "assume makes an ass out of U and me"

Assuming really has made me that, but the U in this context is Wikipedia, which I trusted in so blindly, ... oh well :S

I think that when JMPE equ 0FB8 and POPCNT equ F30FB8 means compatibility problems then its as serious as say:
MOV EAX,90909090h clash with NOPs ^o)

OR: Maybe the answer hides in the fact that you do JMPE to escape from IA-32 and then you do POPCNT when actually its the very same instruction!!! You don't need JMPE (escape from IA-32) in IA-64 mode, do you? You need POPCNT. Maybe its pure ingeniousness (if that's a word).

I've made that mistake a number of times in the past as well, and will probably do it some times in the future too. We should chant to ourselves: "wikiepedia should only be used as a starting point giving hints to where our real research must be done"

No, but i think you meant "ingenuity".