Re: [PATCH] KVM: 'asm' operand has impossible constraints
From: Avi Kivity
Date: Sun Jan 28 2007 - 04:45:32 EST
S.ÃaÄlar Onur wrote:
27 Oca 2007 Cts tarihinde, Avi Kivity ÅunlarÄ yazmÄÅtÄ:
The patch looks correct, but I don't understand the gcc error message.
Are we sure this isn't a gcc 4.2 bug?
"g" appears to be equivalent to "rmi", if "i" is impossible, gcc is free
to use "r" or "m", no?
Accorgind to GCC devs. its not a bug
(http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29808), on comment #5 the
problem described like;
"g" means "r"+"i" so the register allocator in the -O0 case is selecting "r"
while in the optimize case is selecting "i"
That's a different bug. The gcc PR has an assembler error message, as
expected, whereas the kvm miscompile has a compiler error, which I don't
understand.
Anyhow, your patch is correct (because selecting "i" is indeed
erroneous) so I'll apply it, but I'm worried that there's a gcc bug in
there that we ought to report.
--
error compiling committee.c: too many arguments to function
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