[LLVMdev] (no subject)

[Chris Lattner]

On Thu, 5 May 2005, Marshall Spight wrote:
>>>     In other words, abandoning overflow detection makes the
>>>     duplication of types redundant, while requiring it would be a
>>>     great burden on CPUs that don't have overflow exception hardware.
>>
>> Yes, you're right. This has been a desired change for quite some time
>> now. Unfortunately, its a huge impact to nearly every part of LLVM. We
>> will probably do it around the 2.0 time frame when we can afford to
>> break bytecode compatibility and generally clean up a lot of other
>> things as well.
>
> Uh, does this mean you're contemplating getting rid of llvm's ability
> to detect an interger overflow? So if I add, say, two 32-bit signed
> ints with values 2000000000 and 2000000000 I'm going to get
> -294967296 and have no way to know that something bad happened?

LLVM does not have that capability.  Reid is talking about something else. 
Being able to detect overflow is something that I would like to add in the 
future though, which is part of what Reid is referring to.

> That would make me sad. I'm not entirely sure I see the rationale;
> isn't it the case that only languages that care to support such
> overflow detection would pay the runtime cost?

No, we currently do not support overflow detection.

-Chris

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