[FFmpeg-devel] Inline ASM vs. Intrinsics
Fri May 11 16:22:32 CEST 2007
On Fri, May 11, 2007 at 02:06:11PM +0200, Guillaume POIRIER wrote:
> Exactly. I wrongfully assumed that "register" keywork was honnored
> with xmm/mm intrinsics, but I was wrong. It's simply ignored by ICC. I
> don't know about GCC.
According to its documentation gcc also ignores the "register" storage
class specifier, except in a few special cases:
- when using asm in a declaration to explicitly specify which register.
- when using -O0.
- when using setjmp on certain rare target platforms.
Aside: on IA64 icc supports only intrinsics -- no inline assembly. On
the one hand IA64 assembly is so painful that you'd rarely want to
write it manually anyway; but the downside is that the intrinsics
might not expose all of the instruction set's features. For example I
had a case where I wanted an 8-byte store with both the "nta" and
"rel" hints applied, but I couldn't find any way to generate it with
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