[llvm-commits] [llvm] r91497 - in /llvm/trunk: include/llvm/Metadata.h lib/VMCore/Metadata.cpp

[Victor Hernandez]

On Dec 17, 2009, at 12:06 AM, Chris Lattner wrote:

> On Dec 16, 2009, at 10:56 AM, Devang Patel wrote:
> 
>>>> 
>>>> Is this new field copied by MetadataContextImpl::copyMD?
>>> 
>>> The semantic is that if an MDNode is created function-local, then it will continue to be function-local even if its operands are modified to no longer refer to any function-specific IR.
>> 
>> That'll break MDNode unique-ness.
> 
> We don't guarantee MDNode uniqueness, we just endeavor to preserve it when it isn't "too hard".

Devang, you were concerned that 2 MDNodes with identical operands would not be the same if one is function-local and the other is not (can happen if an originally function-local MDNode has its operands modified to match those of a pre-existing non-function-local MDNode).  Are there any issues with making these MDNodes be distinct?

Victor
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