Messages in this thread | | | Date | Fri, 1 Sep 2000 16:01:43 +0300 | From | Matti Aarnio <> | Subject | Re: Large File support and blocks. |
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On Fri, Sep 01, 2000 at 02:44:04PM +0200, Andi Kleen wrote: > > To my knowlege it's only been speed related issues, not > > correctness issues, that have been the cause for the > > fear and loathing of long long. > > There are several parts of XFS which do not compile correctly with gcc > 2.95.2, but do with egcs 1.1 > > For example consider the appended test case. It breaks with 2.95-stable > (from CVS March or so) because the bh->b_blocknr >>= block_bits; > shift is miscompiled. The problem seems to be that it forgets to reload > the %cl register used for the variable shift after the long long shift > before, leading to a bogus shift.
And mind you, that shift operates on 'unsigned long' ! ( Not 'unsigned long long' )
So far there has been only talk of doing the change. Brr...
> Another problem is that linus' do_div in asm-i386/div64.h seems to cause > miscompiled code when used in anything more complicated than printk (no > extracted test case yet sorry)
It really isn't intended for anything else. It is rather terrible side-effect monster..
> Assembly from gcc 2.95 for the > bh->b_blocknr = (long)mp->pbm_bn + > (mp->pbm_offset >> inode->i_sb->s_blocksize_bits); > bh->b_blocknr >>= block_bits; > bh->b_state |= (1UL << 4 );
/Matti Aarnio - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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