[llvm-dev] Aliasing rules difference between GCC and Clang

Jonas Paulsson via llvm-dev llvm-dev at lists.llvm.org
Fri Jan 25 07:44:28 PST 2019

Hi Ivan,

> As to my own patches pending publication, they are all for the new 
> TBAA format, which you said would be of no help in your case.
I actually thought they would help, but merely suggested an intermediate 
step while waiting for those further improvements you are working on. I 
would be happy to try your patches and evaluate if it helps my test case...



> Regards,
> On 22/01/2019 16:02, Jonas Paulsson wrote:
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>> Hi Ivan,
>> On 2019-01-18 10:15, Ivan Kosarev wrote:
>>> IIRC, there were proposals/attempts to represent accesses to array
>>> elements as accesses to their first elements, which can technically be
>>> encoded with the current TBAA format and thus may work as an
>>> incremental improvement on top of the existing TBAA machinery you are
>>> looking for. But this may need making sure there will be no
>>> regressions for some tricky cases like those that involve GCC's type
>>> punning and changing effective types within unions and in dynamic 
>>> memory.
>> It would be interesting for me to apply such a patch and evaluate if it
>> really helps my test case. I would much appreciate any links to (or
>> files of) your patches and the attempts you mentioned above.
>> Thanks,
>> Jonas

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