Short code to determine compiler's
John Hascall
hascall at atanasoff.cs.iastate.edu
Tue Jul 25 00:03:46 AEST 1989
In article <26470 at amdcad.AMD.COM> tim at amd.com (Tim Olson) writes:
>In article <1038 at cernvax.UUCP> hjm at cernvax.UUCP (Hubert Matthews) writes:
>| I have a question for the authors of smart C compilers: is the
>| register declaration useful at all for such compilers?
>
>Yes, the register keyword does indicate such things, but they can all be
>determined by flow analysis anyway.
There are times that the programmer has more information than the
compiler, consider this code fragment for example:
for(i=0; i<foo; i++) ...
for(j=0; j<bar; j++) ...
and suppose the programmer knows `foo' will be large and `bar' will be
small, then hopefully `register int i' could be a hint to the
compiler that the first loop will be executed many times more than
the second--something it has no clue about.
John Hascall
ISU Comp Center
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