9 lines
504 B
Text
9 lines
504 B
Text
Berkeley Yacc reflects its origins. The reason so many routines
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use exactly six register variables is that Berkeley Yacc was
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developed on a VAX using PCC. PCC placed at most six variables
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in registers. I went to considerable effort to find which six
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variables most belonged in registers. Changes in machines and
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compilers make that effort worthless, perhaps even harmful.
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The code contains many instances where address calculations are
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performed in particular ways to optimize the code for the VAX.
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