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From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.std.c
Subject: Re: Are externs automatically volatile?
Message-ID: <13090@smoke.BRL.MIL>
Date: 12 Jun 90 11:52:05 GMT
References: <2213@atari.UUCP>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 12

In article <2213@atari.UUCP> apratt@atari.UUCP (Allan Pratt) writes:
>Are all externs volatile?

No, of course not.

>I had hoped, especially with -fstrength-reduce, that this_is_extern
>would be read into a register once, rather than having the  memory
>reference at the bottom of every loop, but that's not what happened.

Most compilers do not perform such global optimization over externs;
since under many circumstances the optimization would be incorrect,
the compiler writer finds it simpler to not worry about it.