🚀 go-pugleaf

In article <1rs3rb$1bp@almaak.usc.edu> ajayshah@almaak.usc.edu (Ajay Shah) writes:
>These details will vary from one compiler to the next, of course, but
>I don't forsee ever using a C compiler other than gcc, and I'm sure
>many others are in the same situation.

Not only from compiler to compiler: many optimizations vary from
processor to processor!  Just as an exmaple of what you as a
programmer can do, if you are writing for the i386 family, it is
Received Wisdom that you should avoid using `unsigned short', because
the definition of Standard C requires this type to be promoted to
`signed int' in most contexts.  The result is that GCC ends up
emitting a lot of slow sign-/zero-extension instructions (`movzwl'
rings a bell) when working on these types, which are avoided if you
use a full `unsigned int'.  (I'm certain you've read the discussions
on comp.lang.c about unsigned-preserving versus value-preserving
semantics.)

For this particular situation, it would be nice if GCC had a
`-funsigned-preserving' switch.  (A `-muse-halfword-ops' switch would
be nice, too.)

-GAWollman

-- 
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