Fine Tuning Compiler Actions
Compiler performs many sophisticated optimizations on the source code under certain assumption about the program. Typically:
- program data is large (does not fit into the cache)
- program does not violate language standard
- program is insensitive to roundoff errors
- all data in the program is alias-ed, unless it can be proved otherwise
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if one or more of these assumptions does not hold, compiler should be tuned to the program with the compiler options. Most important:
- OPT for general optimizations assumptions
- LNO for the Loop Nest optimizer options
- IPA for the Inter-Procedural Analyzer options
Additional options that help to tune the compiler properly:
- TENV, TARG for the target machine and environment description
-TENV:align_aggregates=x (bytes)
- LIST, DEBUG for the listing and debugging options