Date: Sun, 21 Dec 1997 01:00:25 -0800 (PST) From: Jason Evans <jasone@canonware.com> To: Greg Lehey <grog@lemis.com> Cc: Ric Flinn <rmf@radiks.net>, freebsd-sparc@FreeBSD.ORG Subject: Re: Register windowing Message-ID: <Pine.BSF.3.96.971221003424.367P-100000@mozart.canonware.com> In-Reply-To: <19971221184451.62453@lemis.com>
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On Sun, 21 Dec 1997, Greg Lehey wrote: > I think this sums up the issues pretty nicely. I suppose the only > point to be made is that the number of windows in the register file > varies greatly from one processor to another. Considering the > interest in older processors, the code should be flexible enough to > potentially be able to choose different strategies dependent on the > processor. Some definitions gleaned from manuals (used in this context): register window (or simply window) - An individual group of 24 registers representing the state of a stack frame, as saved when preparing for a function call. register file - The full set of integer registers available to user code. I can't find a term for a group of more than one register window. Is there one? You refer to the register file, but I think you're actually referring to this. The manuals refer to NWINDOWS as being a constant defined by each implementation, but that doesn't work very well for discussions. The sun4u processor has 8 register windows. Anyone know what the sun4m, sun4c, etc. has? If we use a simple solution such as trying to keep half of the windows full, the code won't need to be changed for each processor other than a few constants, but still, it would be good to know for future reference. Jason Jason Evans Email: [jasone@canonware.com] Home phone: [(650) 856-8204] Work phone: [(408) 774-8007] Quote: ["Invention is 1% inspiration, 99% perspiration" - Thomas Edison]
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