>Hello.
>
>I have a question on SSE registers use in
>/on/usr/src/lib/libc/i386_hwcap1/gen/memcpy.s. The code seems to use
>%xmm0, and other SSE registers without saving them before use.
>(.sse_sa_loop for example.)
>
>Wouldn't this cause trouble if a user was using SSE registers in their
>application?

No, the caller needs to save the mmx0-7 registers, as specified
by the ABI.

>I have taken a quick look at NetBSD source code. The comment in their
>code says that FPU states must be saved if the user happens to utilize
>SSE registers in their code.
>(http://fxr.watson.org/fxr/source/i386/i386/bcopy.s?v=DFBSD#L230)

That's the kernel; it plays by different rules as it can be invoked
asynchronously to the user's application.

Casper
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