Merge 252892fea7088abbeff9476e0ecbacc091d135a0 into the 10.0 branch

[yuanfang-chen]

Bugzilla Link	46360
Resolution	FIXED
Resolved on	Jun 23, 2020 14:18
Version	10.0
OS	All
Blocks	#44654
CC	@tstellar
Fixed by commit(s)	252892f 8f299fd

Extended Description

Is it OK to merge the following revision(s) to the 10.0 branch?

[yuanfang-chen]

assigned to @joker-eph

[yuanfang-chen]

https://reviews.llvm.org/rL252892fea7088abbeff9476e0ecbacc091d135a0

[yuanfang-chen]

This helps ThinLTO caching a lot.

commit 252892fea7088abbeff9476e0ecbacc091d135a0
Author:     romanova-ekaterina <katya.romanova@sony.com>
AuthorDate: Tue Jun 9 13:46:28 2020 -0700
Commit:     romanova-ekaterina <katya.romanova@sony.com>
CommitDate: Wed Jun 10 12:41:41 2020 -0700

    Fixed false ThinLTO cache misses problem (PR 45819).

    We relied on the fact that the iterators walks through the elements of a
    DenseSet in a deterministic order (which is not true). This caused
    ThinLTO cache misses. This patch addresses this problem.
    See PR 45819 for additional information
    llvm/llvm-bugzilla-archive#45819 

    Differential Revision: https://reviews.llvm.org/D79772

[tstellar]

Mehdi, what is your opinion about backporting this?

https://reviews.llvm.org/rG252892fea7088abbeff9476e0ecbacc091d135a0

[joker-eph]

Seems like low-risk: the cache is invalidate on a new version of the compiler anyway.

Adding Teresa to get a second opinion?

[llvmbot]

I agree, think it would be good and low risk to merge.

[tstellar]

Merged: 8f299fd