[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86/time: fix scale_delta() inline assembly
On 26/11/2012 17:12, "Ian Campbell" <Ian.Campbell@xxxxxxxxxx> wrote: >> That's how things are with multi-insn asm-s (and even with single- >> insn ones when an output different from an input get tied together >> through using the same register). I continue to think that using the >> numbered forms here is better. > > I think the important difference here is that the mul generates its > result specifically in rdx:rax rather than user specified registers. > Since the output is not specified via the constraints IMHO using the > constraints when subsequently consuming those outputs is confusing. > > I'd agree with you if mul was something like "mul %2,%0,%1" (where %2*% > rax =>%0:%1) then "shrd $32,%0,%1" would be perfectly fine. > > Anyway I guess we'll have to agree to disagree. In any case your opinion > trumps mine on this code ;-) I didn't find Jan's asm particularly confusing, any more than it kind of fundamentally is. It's fine by me for it to go in as it is. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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