Are SSE registers preserved?

[Alloy]

  I was wondering if the SSE registers need to be preserved when calling Windows API functions.

[Farabi]

Do you mean SSE is alike MMX.

[Alloy]

 The XMM0 through XMM7 registers.

[roticv]

I'm not really sure and wouldn't count on it.

[bozo]

Its possible that the floating point area of the processor could be modified with an api call.
Therefore..you should save the FPU state beforehand, just to be safe.

it wasn't really an issue up until 64-bit version of windows (AFAIK)
but the FPU and MMX are pretty much the same area..i think.

if you modify st(0) for example, you also modify MM0

Under the debugger, XMM0 seemed unchanged..

maybe someone else knows more about it.

[OceanJeff32]

Don't quote me on this, but I think I read somewhere, that Windows API doesn't yet use the SSE/SSE2 because of compatibility reasons...?

I was under the impression that unless you call Direct X or other graphic functions, you don't need to worry.  But I'm not sure where I read that.

I guess if you search through the API listing at microsoft.com for SSE, that would tell you, but I've never seen any references to the SSE architecture in all the books I've read on Windows Programming, unless they talk about Graphics.

Later,

Jeff C
:green

P.S. Of course

[MazeGen]

It is really strange that msdn doesn't document it for x32. As for x64, it is clear, look here.

[bozo]

As for x64, it is clear

i wonder does this mean that using MMX is not recomended by microsoft
on 64-bit platform??

[MazeGen]

Exactly :(

The FPU and MMX state is not preserved accross context switches, what means FPU and MMX is useless under win x64.