Can ANSI Standard C be "Optimized"

Martin Minow minow at decvax.UUCP
Tue Mar 13 11:23:49 AEST 1984


In the interesting and well-detailed series of optimization
comparisons between C and Bliss, it was pointed out several
times that Bliss performs many multi-statement optimizations
the C ignores.

If I read the Draft ANSI Standard correctly, it would seem to preclude
any optimizations across statement (;) boundaries.  Thus, simple for
satements cannot take advantage of loop control instructions such
as SOB on the PDP-11.

Therefore, many of the failings of the C optimizers are inherent
in the definition of the language, and not simply due to laziness
on the part of the compiler writers.  (And, no, I don't know
why this restriction was put in the draft standard.)

Martin Minow
decvax!minow



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