[LLVMdev] a question about constant fold for fdiv

[Chris Lattner]

On Thu, 22 Mar 2007, Jeff Cohen wrote:
> Jeff Cohen wrote:
>>  The standard apparently doesn't explicitly handle 0/0, but the position of 
>>  the IEEE appears to be that it should yield a NaN of the appropriate sign. 
>>  See http://standards.ieee.org/reading/ieee/interp/754-1985.html
>
> OK, it does explicitly handle it.  My reading comprehension seems to be 
> lacking right now :(
>
> http://754r.ucbtest.org/standards/754xml.html#invalid-exception
>
> The above lists all operations that yield a NaN.

Sounds like a bug, please file it or fix it :)  The code in question is 
VMCore/ConstantFold.cpp:654.  It should produce the appropriately signed 
NaN instead of Inf.

-Chris

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