<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Treating the 0 page as a big register file (and A, X, Y as special registers) makes it quite GPU-like, in that it makes for a fairly large arbitrarily-addressed register file (rather than distinct, disjoint registers like a CPU). There’s also a number of GPUs that have special registers that are “cheaper” or required to actually do ops on, so again, it seems familiar, at least in that sense!<div class=""><br class=""></div><div class="">—escha</div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Feb 12, 2016, at 9:34 AM, Bruce Hoult <<a href="mailto:bruce@hoult.org" class="">bruce@hoult.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">Not having looked at GPU architectures or programming, what aspect are you referring to? Static assignment of local variables? Of course that was standard in FORTRAN and COBOL days.</div><div class="gmail_extra" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br class=""><div class="gmail_quote">On Fri, Feb 12, 2016 at 6:05 PM,<span class="Apple-converted-space"> </span><span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:escha@apple.com" target="_blank" class="">escha@apple.com</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><div style="word-wrap: break-word;" class="">I never thought I’d see the day when someone proposed treating the 6502 like a GPU…<div class=""><br class=""></div><div class="">—escha</div><div class=""><div class="h5"><div class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Feb 12, 2016, at 6:30 AM, Bruce Hoult via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank" class="">llvm-dev@lists.llvm.org</a>> wrote:</div><br class=""><div class=""><div dir="ltr" class="">I think it would be sufficient to pick 8 or 16 pairs of zero page locations as the "registers". Who needs 128 registers, unless you're also doing inter-procedural register allocation? True, that would be a good idea, so non-recursive functions can be allocated a fixed set of registers (based on the maximum call depth they are used from?) and never need to save/restore anything. That would be useful for other CPUs too. but LLVM doesn't support this.<div class=""><br class=""></div><div class="">As for treating 1-2 as a register as well as 0-1 and 2-3? Theoretically possible, of course, but needless complexity.</div></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Fri, Feb 12, 2016 at 4:54 PM, Krzysztof Parzyszek via llvm-dev<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:llvm-dev@lists.llvm.org" target="_blank" class="">llvm-dev@lists.llvm.org</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><span class="">On 2/12/2016 7:23 AM, Bruce Hoult via llvm-dev wrote:<br class=""><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;">I haven't seen what you are doing, but if I was writing a back end for<br class="">the 6502, I'd lie to LLVM and describe RAM page 0 as being the real<br class="">registers, and A, X and Y as being special purpose registers used for<br class="">temporaries.<br class=""></blockquote><br class=""></span>How did you get the "(z), x" and "(z, y)" addressing modes to work with this scheme? The "z" is two adjacent zero-page bytes---did you model 16-bit registers as all possible pairs of adjacent 0p addresses?<br class=""><br class="">-Krzysztof<span class=""><font color="#888888" class=""><br class=""><br class="">--<span class="Apple-converted-space"> </span><br class="">Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation</font></span><div class=""><div class=""><br class="">_______________________________________________<br class="">LLVM Developers mailing list<br class=""><a href="mailto:llvm-dev@lists.llvm.org" target="_blank" class="">llvm-dev@lists.llvm.org</a><br class=""><a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev" rel="noreferrer" target="_blank" class="">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a><br class=""></div></div></blockquote></div><br class=""></div>_______________________________________________<br class="">LLVM Developers mailing list<br class=""><a href="mailto:llvm-dev@lists.llvm.org" target="_blank" class="">llvm-dev@lists.llvm.org</a><br class=""><a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev" target="_blank" class="">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a><br class=""></div></blockquote></div><br class=""></div><br class=""></div></div><span class="HOEnZb"><font color="#888888" class="">--<span class="Apple-converted-space"> </span><br class="">This message has been scanned for viruses and<span class="Apple-converted-space"> </span><br class="">dangerous content by<span class="Apple-converted-space"> </span><a href="http://www.mailscanner.info/" target="_blank" class=""><b class="">MailScanner</b></a>, and is<span class="Apple-converted-space"> </span><br class="">believed to be clean.</font></span></div></blockquote></div></div></div></blockquote></div><br class=""></div></body></html>