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Diffstat (limited to 'contrib/byacc/NOTES')
| -rw-r--r-- | contrib/byacc/NOTES | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/contrib/byacc/NOTES b/contrib/byacc/NOTES new file mode 100644 index 0000000..9db3c96 --- /dev/null +++ b/contrib/byacc/NOTES @@ -0,0 +1,9 @@ +Berkeley Yacc reflects its origins. The reason so many routines +use exactly six register variables is that Berkeley Yacc was +developed on a VAX using PCC. PCC placed at most six variables +in registers. I went to considerable effort to find which six +variables most belonged in registers. Changes in machines and +compilers make that effort worthless, perhaps even harmful. + +The code contains many instances where address calculations are +performed in particular ways to optimize the code for the VAX. |
