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From: Terry Lambert <terry@lambert.org>
Message-Id: <199601180550.WAA04806@phaeton.artisoft.com>
Subject: Re: src/lib/libc/sys/Makefile.inc: proposed change
To: jdp@polstra.com (John Polstra)
Date: Wed, 17 Jan 1996 22:50:43 -0700 (MST)
Cc: freebsd-current@FreeBSD.org
In-Reply-To: <199601180127.RAA19205@austin.polstra.com> from "John Polstra" at Jan 17, 96 05:27:17 pm
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> I want to see if anybody envisions any problems with a change I want to
> make to it.
> 
> I was making a modified local version of the libc tree for generating
> an ELF library.  That involved creating a couple of new preprocessor
> macros, and using them in some of the assembly language files.  I
> don't have the precise details handy, but an assembly died on a
> statement something like this:
> 
> 	movl	$FOO,%eax
> 
> where "FOO" was one of the new macros I defined.
> 
> The problem was that, by default, "cpp" considers `$' to be a valid
> character in an identifier.  So it was interpreting `$FOO' as an
> identifier, rather than as two separate tokens.  This is never correct
> in i386 assembly language, since `$' is an operator that means
> "interpret as a literal".
> 
> So I want to modify "Makefile.inc" in that directory so that cpp is
> invoked with the "-$" option, which makes `$' _not_ a valid identifier
> character.  (Yes, I know I have to double the dollar sign in the
> makefile.)  I tried it locally, and it seemed to work fine.
> 
> Do any of you see any problem with making that change?


Why not:

 	movl	$ ## FOO,%eax

Instead?

If it hits the preprocessor first, it should be no problem.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.