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| author | rgrimes <rgrimes@FreeBSD.org> | 1994-05-27 12:33:43 +0000 |
|---|---|---|
| committer | rgrimes <rgrimes@FreeBSD.org> | 1994-05-27 12:33:43 +0000 |
| commit | f9ab90d9d6d02989a075d0f0074496d5b1045e4b (patch) | |
| tree | add7e996bac5289cdc55e6935750c352505560a9 /usr.bin/yacc/NOTES | |
| parent | be22b15ae2ff8d7fe06b6e14fddf0c5b444a95da (diff) | |
| download | FreeBSD-src-f9ab90d9d6d02989a075d0f0074496d5b1045e4b.zip FreeBSD-src-f9ab90d9d6d02989a075d0f0074496d5b1045e4b.tar.gz | |
BSD 4.4 Lite Usr.bin Sources
Diffstat (limited to 'usr.bin/yacc/NOTES')
| -rw-r--r-- | usr.bin/yacc/NOTES | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/usr.bin/yacc/NOTES b/usr.bin/yacc/NOTES new file mode 100644 index 0000000..9db3c96 --- /dev/null +++ b/usr.bin/yacc/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. |
