[Vm-dev] [commit] r2463 - CogVM source as per
VMMaker.oscog-eem.105. Fix signed32BitValueOf for most neg-
squeak at stefan-marr.de
Thu Jul 21 22:17:10 UTC 2011
On 21/07/11 19:35, Eliot Miranda wrote:
> On Thu, Jul 21, 2011 at 4:30 AM, David T. Lewis <lewis at mail.msen.com
> <mailto:lewis at mail.msen.com>> wrote:
> Hi Eliot,
> Can you say what the issue was with signed32BitValueOf? I can
> see the changes in InterpreterPrimitives>>signed32BitValueOf:
> but I'm not clear on whether this is something that affects
> Alien, or if it is something that has been causing problems
> more generally but went unnoticed. Also, I'd like to document
> this with a unit test, so if you can suggest a code snippet
> that would be great.
> The unit test is in the lien tests and is the attempt to assign max
> neg int (-2^31) through signedLongAt:put:. The problem is due to a
> pervasive C compiler bug with optimization.
Maybe I misread this blog post:
(*Signed integer overflow:)*
but from that I would conclude that it is not a compiler bug, but
undefined behavior in C instead. Thus, GCC and ICC are just doing there
job in terms of what they are allowed to do by the spec.
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