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From:	"Carlo Bramini" <cbramix AT libero DOT it>
Newsgroups:	comp.os.msdos.djgpp
Subject:	From GCC 2.7.2.1 to GCC 3.0.3
Date:	Sun, 3 Feb 2002 10:02:07 +0000 (UTC)
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Hi.
I'm a user of DJGPP and my compiler version was 2.7.2.1
I have downloaded GCC 3.0.3 and it works fine too, but I have noticed
some "strange" things...
For example, I have a program with a lot of lines like that:

m = ~m;

and the new compiler translates it into:

xorl $-1,%ebx

instead of:

notl %ebx

The program works exactly, of course, but the "xor" opcode requires 1
byte more than the "not" one.
"Not" should be able to go into both pipes of Pentium CPU, exactly like
"xor", so I don't understand the reason of that.
And since this code is executed *many* times, it would be better to use
the space of a cache line in the best way.

Maybe I'm doing something wrong with the new compiler, so I'm asking
here to people more expert than me on version 3.0.3

Sincerely,

Carlo

PS: I'm not an english native speaker, please excuse my errors.


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