>>> On 27.06.19 at 14:00, <ubiz...@gmail.com> wrote: > On Thu, Jun 27, 2019 at 1:46 PM Jan Beulich <jbeul...@suse.com> wrote: >> >> >>> On 27.06.19 at 13:09, <ubiz...@gmail.com> wrote: >> > On Thu, Jun 27, 2019 at 12:11 PM Jan Beulich <jbeul...@suse.com> wrote: >> >> >> >> Without these constraints asm() can't make use of mask registers. >> > >> > asm should be deprecated. We have intrinsics for this purpose. >> >> While maybe not explicitly applicable here, the intrinsics aren't >> (afaict) providing full flexibility. In particular (just as example) >> I haven't found a way to use embedded broadcast with the >> intrinsics, but I can easily do so with asm(). >> >> Furthermore there are other reasons to use asm() - things like >> the Linux kernel are full of it for a reason. And once one has >> to use asm(), the resulting code typically is easier to follow if >> one doesn't further intermix it with uses of builtins. >> >> And finally, if asm() was indeed meant to be deprecated, how >> come it pretty recently got extended to allow for "inline"? > > I didn't mean that asm() in general should be deprecated, but for SSE > and other vector extensions, where intrinsics are available, > intrinsics should be used instead. There was exactly zero requests to > use new asm constraints, it looks that people are satisfied with > intrinsics approach (which is also future-proof, etc).
So what about my embedded broadcast example then? "Zero requests" is clearly not exactly right. It simply didn't occur to me (until I noticed the @internal here) that I should raise such a request, rather than just using asm(). Subsequently I did then notice "Yh" going away, complicating things further ... I'd also like to note that the choice of types on some of the builtins makes it rather cumbersome to use them. Especially for scalar operations I've found myself better resorting to asm(). See https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=tools/tests/x86_emulator/simd.c (most of the changes submitted (not so) recently have been coming from the work of putting together this and its sibling tests for the Xen Project instruction emulator). Jan
