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| author | Fangrui Song <maskray@google.com> | 2019-02-28 05:16:01 +0000 |
|---|---|---|
| committer | Fangrui Song <maskray@google.com> | 2019-02-28 05:16:01 +0000 |
| commit | e931931b34cebf132b601374399f021105434c32 (patch) | |
| tree | 22feb1c365c3165270b0732eb2b3d8057e9374b3 /llvm/test/Transforms/InstCombine/saturating-add-sub.ll | |
| parent | 21020bf015aa15af503e9ae8a56314b15ee93e07 (diff) | |
| download | bcm5719-llvm-e931931b34cebf132b601374399f021105434c32.tar.gz bcm5719-llvm-e931931b34cebf132b601374399f021105434c32.zip | |
[Dominators] Avoid potentially quadratic std::is_permutation
Summary:
If the two sequences are not equal, std::is_permutation may be O(N^2)
and indeed the case in libstdc++ and libc++. Use SmallPtrSet to prevent
pessimizing cases. On my machine, SmallPtrSet starts to outperform
std::is_permutation when there are 16 elements.
Reviewers: kuhar
Reviewed By: kuhar
Subscribers: kristina, jdoerfert, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58373
llvm-svn: 355070
Diffstat (limited to 'llvm/test/Transforms/InstCombine/saturating-add-sub.ll')
0 files changed, 0 insertions, 0 deletions
