[PATCH] D36963: Use sorting instead of a lot of stable_partitions for `ICF::segregate` function

[Zachary Turner via Phabricator via llvm-commits]

zturner added inline comments.


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Comment at: lld/COFF/ICF.cpp:99
+
+  // I'm not sure if regular sort can be used here
+  std::stable_sort (Chunks.begin() + Begin, Chunks.begin() + End, Less);
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ruiu wrote:
> This comment is not useful because it poses a question to a reader instead of answering a question for a reader.
> 
> You cannot actually use std::sort because we want a deterministic output in general. For a set of input files, there are a lot of valid link results for it, but we always want to output the same file, as it is important for build reproducibility.
Using `std::sort` should not affect determinism right?  If you call `std::sort` two times with an identical input data set, you are guaranteed to get the same results.  The only thing `stable_sort` does is preserve relative ordering.  Even though `std::sort` doesn't preserve that ordering, ti still produces deterministic output.


https://reviews.llvm.org/D36963