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| author | Daniel Berlin <dberlin@dberlin.org> | 2017-01-13 22:40:01 +0000 |
|---|---|---|
| committer | Daniel Berlin <dberlin@dberlin.org> | 2017-01-13 22:40:01 +0000 |
| commit | c0431fd02d24b86e3b2a9d029cb44e93aaf77efe (patch) | |
| tree | 41041542cce2af4d4788fa877163c44bce115795 /llvm/lib/CodeGen/ResetMachineFunctionPass.cpp | |
| parent | c109bbea57c2df9edb983177ec1c998bd946d23a (diff) | |
| download | llvm-c0431fd02d24b86e3b2a9d029cb44e93aaf77efe.zip llvm-c0431fd02d24b86e3b2a9d029cb44e93aaf77efe.tar.gz llvm-c0431fd02d24b86e3b2a9d029cb44e93aaf77efe.tar.bz2 | |
NewGVN: Move leaders around properly to ensure we have a canonical dominating leader. Fixes PR 31613.
Summary:
This is a testcase where phi node cycling happens, and because we do
not order the leaders by domination or anything similar, the leader
keeps changing.
Using std::set for the members is too expensive, and we actually don't
need them sorted all the time, only at leader changes.
We could keep both a set and a vector, and keep them mostly sorted and
resort as necessary, or use a set and a fibheap, but all of this seems
premature.
After running some statistics, we are able to avoid the vast majority
of sorting by keeping a "next leader" field. Most congruence classes only have
leader changes once or twice during GVN.
Reviewers: davide
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D28594
llvm-svn: 291968
Diffstat (limited to 'llvm/lib/CodeGen/ResetMachineFunctionPass.cpp')
0 files changed, 0 insertions, 0 deletions