tree 51d59ce97099aab9fe4e772e958dd171ca06597f
parent da418fcf9d440fb8006255ac208c5497496a222d
author Fangrui Song <maskray@google.com> 1570175814 +0000
committer Fangrui Song <maskray@google.com> 1570175814 +0000

[ELF] Use union-find set and doubly linked list in Call-Chain Clustering (C³) heuristic

Before, SecToClusters[*] was used to track the belonged cluster.
During a merge (From -> Into), every element of From has to be updated.
Use a union-find set to speed up this use case.

Also, replace `std::vector<int> Sections;` with a doubly-linked
pointers: int Next, Prev;

Reviewed By: Bigcheese

Differential Revision: https://reviews.llvm.org/D46228

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@373708 91177308-0d34-0410-b5e6-96231b3b80d8