Date: Sun, 27 Feb 2011 14:04:00 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Dimitry Andric <dim@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r219079 - in head/sys/boot/i386: gptboot gptzfsboot zfsboot Message-ID: <20110227133227.S1974@besplex.bde.org> In-Reply-To: <201102270206.p1R269VO021432@svn.freebsd.org>
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On Sun, 27 Feb 2011, Dimitry Andric wrote: > Log: > Clang's integrated assembler can now handle sys/boot/i386/boot2/sio.S. > It used to choke on the notation "inb (%dx),%al" for "inb %dx,%al"; GNU > as accepts both forms. Which notation is more 'correct' is an open > question. :) Nah, the former is just a syntax error since %dx is not dereferenced :-). It is a syntax error at the design level that parentheses are used for indirection. In better assembler syntaxes like Intel/Microsoft's one for x86 and Motorola's one for 6809, brackets are used for indirections so parentheses are not context-dependent. Then extra parentheses around expressions can have no effect. But dx isn't an expression, so (dx) should still be a syntax error. I think it is in I/M syntax but I can't test that easily. It is a syntax error in my x86/6809 assembler. My assembler doesn't check, but emits a diagnostic for this :-). (My assembler wants brackets for indirection, but it has an option to to implement some bugs including use of parentheses for indirection.) Brucehome | help
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