Re: Fast code vs. fast compile

Dennis Yelle <dennis@netcom.com> wrote:
|> As a compiler user, I am (almost) always more concerned about fast
|> code rather than fast compilation.
|> ...
|> [Perhaps you don't work on very large programs. A few years back when I
|> was recompiling a 600,000 line C program on three platforms every night,
|> I would have been extremely pleased to have a faster compiler available
|> than GCC. -John]


Daniel J. Salomon wrote:
> Actually the two speeds, compilation versus execution, are sometimes related.


As far as my own experience is concerned, compilation speed remains
very important, specially in cases where a low-level language such as
C is used as intermediate language in a large compilation context. In
such cases, the amounts of code that must be compiled can go as far as
a 1.000.000 lines (that is approximatively the amount of C code that
is recompiled here every night. It only represents 140.000 lines of
YAFL code, compiled twice, once with full debugging support, once with
full optimization enabled).


On the other hand, I don't think (intuition only, please feel free to
tell me how wrong I can be) that every execution time improvement
improves the compilation time by similar factors. After that very
basic optimizations have been implemented, every additional % to gain
requires its load of sweat and frustration, and the compiler might
perform lengthy analysis for a very little performance improvement, if
any. In some cases, the performance improvement does not apply to the
compiler itself, which is perhaps not a very typical benchmark
program. In some other cases, the compiler might optimize space rather
than speed...


Well, IMO...


Darius
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