On Mon, Mar 08, 2010 at 06:47:46PM +0100, sean finney wrote:
> hey folks,
> 
> just to throw something out there, the last time i ran into a bug like
> this was a few weeks back with php, also with gcc 4.4 and also on arm.
> turns out it was a case of signed integer overflow, which has undefined
> consequences in runtime code.

thanks for the hint, that might make sense.

> looking through the code i see comments that show some awareness of this
> but also some constants which are a bit suspicious.  namely, grep around
> for -0x80000000 and similar, which are invalid values for signed int32's,
> etc.

actually, from /usr/lib/limits.h, -0x80000000 is indeed the minimum
value for signed int32. a brief look at the tests failing show that this
is exactly what upstream tries to test, the minimum and maximum valid
signed values.  whether they do this correctly or not i don't know yet.

> i couldn't say that i'm confident that this actually is the problem, but
> i think blaming the compiler really ought to be the last resort.  i'm
> somewhat half-interestedly playing around with a compile on agricola atm,
> if i find anything i'll be sure to share.

thanks. i've also managed to get a qemu-based armel machine, and even
though it's slow as hell, at least i'm not disturbing other people. so
now i'm trying to debug this, as much as i can.

iustin



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