xref: /netbsd-src/external/bsd/byacc/dist/NOTES (revision 333e4288417bef01e8ae4ef4e6de82fbdc9ccfbd)
1$NetBSD: NOTES,v 1.2 2009/10/29 00:56:19 christos Exp $
2
3Berkeley Yacc reflects its origins.  The reason so many routines
4use exactly six register variables is that Berkeley Yacc was
5developed on a VAX using PCC.  PCC placed at most six variables
6in registers.  I went to considerable effort to find which six
7variables most belonged in registers.  Changes in machines and
8compilers make that effort worthless, perhaps even harmful.
9
10[Given the previous paragraph, and the fact that GCC does not respect
11 register declarations, and the fact that much of the rest of the
12 4.4lite2 release had "register" declarations extirpated, I've removed
13 most of the register declarations from the code. I left them in the
14 generated skeleton code "for the hell of it" but they probably should
15 go from there, too. -- pm, July 1997]
16
17[I totally removed the register stuff; we've deprecated it elsewhere
18 in the tree now -- lukem, October 1997]
19
20The code contains many instances where address calculations are
21performed in particular ways to optimize the code for the VAX.
22