Re: COP0_SYNC definition

[<Paul_Koning%Dell.com@localhost>]

> On Jun 18, 2016, at 9:35 AM, coypu%SDF.ORG@localhost wrote:
> 
> Hi,
> 
> We define in sys/arch/mips/include/cpuregs.h:157
> #  define JR_HB_RA              .set push; .set mips32r2; jr.hb ra; nop;
> 
> for case of MIPSnnR2 only.
> 
> I think that either this nop is superfluous, or it should be ehb/ssnop.
> I can't imagine a new implementation will ever require just a simple nop
> as padding, aren't they all likely superscalar?

ehb and ssnop tend to show up in "hazards", where the whole pipeline needs to be delayed for some number of cycles.  I don't know what a jr.hb is, but that looks like the standard MIPS branch delay slot.  Branch delay slots are filled with plain NOP when there's nothing useful to put in them.

	paul