HP 3000 Manuals HP 3000 Manuals
Writing Programs That Are Easily Optimized
To maximize the opportunities for optimization and the speed with which
your program is optimized, observe the following guidelines whenever
possible:
* Specify all possible assumptions with the ASSUME compiler option.
* Do not use system programming extensions (specify ASSUME
'PASCAL_FEATURES').
* Use local variables and parameters instead of global variables
(this helps the optimizer promote variables to registers).
* Don't use CRUNCHED, PACKED, or shortint variables.
* Don't put pointer fields in variant parts of records.
* Use unique types as often as possible (this helps the optimizer
determine which variables are possible actual parameters for the
formal parameters of routines).
* Make routines relatively small--approximately 50 executable lines
maximum (this allows the optimizer to use registers more
efficiently).
* Expand in-line any routine of fewer than five lines and any
relatively small routine that your program calls only once (see
"INLINE" in Chapter 8 ).
* Do not write a loop that contains only a routine call; put the
loop in the routine instead, or use the INLINE compiler option.
* Design loops that terminate when their control values are zero or
nil.
* Use WITH statements.
* Do not use the FORWARD and EXTERNAL directives without the ASSUME
compiler option.
* Do not use the GOTO statement.