From: utzoo!decvax!ucbvax!CAD:tektronix!zehntel!sytek!syteka!olmstead
Newsgroups: net.unix-wizards
Title: Optimize my kernel?
Article-I.D.: syteka.286
Posted: Mon Feb 21 19:38:15 1983
Received: Wed Feb 23 03:16:33 1983

I recently noticed that the compiler never gets a -O flag when
compiling our kernel (well, actually, it does when it compiles vers.c,
but that hardly counts).  Before I go ahead and turn it on, can anyone
tell me whether that's a bad idea?  I've seen examples of the
optimizer's generating bad code, but I think that was all
floating-point stuff.  Will it break our UN*X?  Will it cause all those
funky sed scripts to fail?

[I ask this last one because I once added some code to call spl7() from
a function that declared a register variable and initialized it to
TS_OK (= 0).  The compiler cleverly remembered that it had a zero handy
in the register and called spl7 via "calls reg, _spl7" or some such.
The sed script later tried to change all calls to splX into inline
instructions; it KNEW, of course, that these appeared
as "calls, $ 0, _splX" (the space is there so somebody's news
doesn't eat my dollar-zero).  The end result was that the loader told me
that spl7 was undefined.]

So, to optimize or not to optimize: that is the question.
				TIA,
				Patrick Olmstead

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