[llvm-commits] [llvm] r76495 - /llvm/trunk/docs/LangRef.html

[Dan Gohman]

On Jul 20, 2009, at 7:32 PM, Eli Friedman wrote:


> On Mon, Jul 20, 2009 at 3:41 PM, Dan Gohman<gohman at apple.com> wrote:
>
>> Author: djg
>>
>> Date: Mon Jul 20 17:41:19 2009
>>
>> New Revision: 76495
>>
>>
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=76495&view=rev
>>
>> Log:
>>
>> Documentation for the new non-overflow and exact keywords.
>>
>
> Could you add an example to LangRef for the "<result> = signed
> unsigned add <ty> <op1>, <op2>" form?

Done.

>
> We need to clean up the usage of "undefined behavior" vs. "undefined
> result"; we depend on the distinction in various places in the
> optimizer.  For example, a load from an uninitialized alloca has an
> undefined result, but using that result as the argument to another
> load has undefined behavior.  (Note that this only applies within
> LLVM; common languages, like C, don't make this distinction.)

The intention of the new flags I'm working on is to make the result
value of the instruction undefined in certain cases, and not to
produce general undefined behavior. I've now clarified this in
the documentation.

Dan