source: trunk/minix/commands/byacc/NOTES@ 9

Last change on this file since 9 was 9, checked in by Mattia Monga, 14 years ago

Minix 3.1.2a

File size: 504 bytes
RevLine 
[9]1Berkeley Yacc reflects its origins. The reason so many routines
2use exactly six register variables is that Berkeley Yacc was
3developed on a VAX using PCC. PCC placed at most six variables
4in registers. I went to considerable effort to find which six
5variables most belonged in registers. Changes in machines and
6compilers make that effort worthless, perhaps even harmful.
7
8The code contains many instances where address calculations are
9performed in particular ways to optimize the code for the VAX.
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