[PATCH] D125278: [GlobalOpt] Relax the check for ctor priorities

[Alexander Shaposhnikov via Phabricator via llvm-commits]

alexander-shaposhnikov added inline comments.


================
Comment at: llvm/lib/Transforms/Utils/CtorUtils.cpp:159
       continue;
     }
   }
----------------
rnk wrote:
> It looks to me that we attempt to fold any and all constructors, and we don't stop after we fail to evaluate one of them. I think stopping on the first one that fails would be sound. Effectively, it is "as if" the first constructors ran before the first constructor which cannot be folded.
> 
> This is, however, quite unsatisfying since it would prevent folding `gv3` in my linked example, but that's kind of the point.
Oh, right. 
To preserve the current behavior for the case when all the constructors in llvm.global_ctors have the same priority
we can do the following:
1/ llvm.global_ctors "splits" into groups by priority (in a "stable" manner)
2/ The groups are evaluated in order (according their priorities) and  within a given group the evaluation works as before
3/ If we have fully evaluated & committed group_1, group_2, ... , group_n and can't fully evaluate group_{n+ 1} - then we stop (do not attempt to process group_{n + 2}, group_{n + 3} ... since the state is unknown).
Does this sound reasonable / have I missed something ?


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  https://reviews.llvm.org/D125278/new/

https://reviews.llvm.org/D125278