[llvm-commits] [llvm] r167912 - in /llvm/trunk: lib/CodeGen/SelectionDAG/DAGCombiner.cpp test/CodeGen/X86/pr14333.ll

[Rafael Espíndola]

So, is this ok for 3.2?

On 14 November 2012 09:37, Rafael Espíndola <rafael.espindola at gmail.com> wrote:
>> On 14/11/12 14:09, Rafael Espíndola wrote:
>>>
>>> Can we include this in 3.2?
>>
>>
>> maybe RAUW itself should loop like this?  After all, who expects a RAUW to
>> leave
>> uses around?
>
> Not sure, the implementation has this comment:
>
>   // Iterate over all the existing uses of From. New uses will be added
>   // to the beginning of the use list, which we avoid visiting.
>   // This specifically avoids visiting uses of From that arise while the
>   // replacement is happening, because any such uses would be the result
>   // of CSE: If an existing node looks like From after one of its operands
>   // is replaced by To, we don't want to replace of all its users with To
>   // too. See PR3018 for more info.
>
> The problem is that some of the uses introduced by CSE might not have
> the same properties that caused the caller to decide to replace all
> (existing) uses. Maybe replaceAllUsesWith should be
> replaceAllExistingUsesWith and replaceAllUsesWith would include this
> loop?
>
>> Ciao, Duncan.
>
> Cheers,
> Rafael