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Re: stop using P_, __P in header files

From: Stephen J. Turnbull
Subject: Re: stop using P_, __P in header files
Date: Tue, 06 Jul 2010 13:32:44 +0900

Ken Raeburn writes:

 > Do the non-GCC compilers (those that have halfway decent
 > optimizers) still need "register" these days to indicate what
 > variables belong in registers, or do the optimizers do a reasonable
 > job of working it out for themselves?

In principle, "register" is still occasionally useful.  If you have a
large number of variables in a loop which has two long branches, then
which variables belong in registers depend on which branch is taken
more often, something that the compiler cannot know.

OTOH, without profiling typically the programmer won't know, either.

Also, "large" depends on the number of registers available, of course.
In the case of x86, "large" is pretty small, about 8-10 IIRC.

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