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Re: question regarding asm()
- To: Michael Meissner <meissner at cygnus dot com>
- Subject: Re: question regarding asm()
- From: Bernd Schmidt <crux at Pool dot Informatik dot RWTH-Aachen dot DE>
- Date: Mon, 20 Oct 1997 13:28:56 +0200 (MET DST)
- cc: law at cygnus dot com, rth at cygnus dot com, pcg at goof dot com, egcs at cygnus dot com
> I hoped to start looking at this. I am concerned about breaking the
> Linux kernel due to changing semantics. Have you considered changing
> it so it still has the same semantics regarding input/output reloads?
The kernel has been broken before by GCC changes. You can't compile Linux 1.2
with GCC 2.7.2.
The problem is, what exactly _are_ the current semantics for asm statements
on the x86? As far as I can tell, the clobbers are more or less ignored,
which is clearly wrong. I think it would be best to make the constraint
checking for asm statements more strict, even if that means that kernel
patches will become necessary.
BTW, could we increase MAX_RECOG_OPERANDS right now? This would make writing
correct asm statements a lot easier. I'll provide a patch if necessary.
Bernd