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| author | Dale Johannesen <dalej@apple.com> | 2010-07-20 00:50:13 +0000 |
|---|---|---|
| committer | Dale Johannesen <dalej@apple.com> | 2010-07-20 00:50:13 +0000 |
| commit | bf1ae5e254f8f6f6f3dfe9438d14bef9b955f01f (patch) | |
| tree | e13d8954f65191d5d1ef6ef416fe0a20e511e98a /lib/CodeGen/MachineLICM.cpp | |
| parent | 7a2b701ef6a294170fb92a535d52bc533778acff (diff) | |
| download | llvm-bf1ae5e254f8f6f6f3dfe9438d14bef9b955f01f.tar.gz llvm-bf1ae5e254f8f6f6f3dfe9438d14bef9b955f01f.tar.bz2 llvm-bf1ae5e254f8f6f6f3dfe9438d14bef9b955f01f.tar.xz | |
Don't hoist things out of a large switch inside a
loop, for the reasons in the comments. This is a
major win on 253.perlbmk on ARM Darwin. I expect it
to be a good heuristic in general, but it's possible
some things will regress; I'll be watching.
7940152.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108792 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/MachineLICM.cpp')
| -rw-r--r-- | lib/CodeGen/MachineLICM.cpp | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/lib/CodeGen/MachineLICM.cpp b/lib/CodeGen/MachineLICM.cpp index 4c054f51f3..83f66ce094 100644 --- a/lib/CodeGen/MachineLICM.cpp +++ b/lib/CodeGen/MachineLICM.cpp @@ -489,8 +489,12 @@ void MachineLICM::HoistRegion(MachineDomTreeNode *N) { } const std::vector<MachineDomTreeNode*> &Children = N->getChildren(); - for (unsigned I = 0, E = Children.size(); I != E; ++I) - HoistRegion(Children[I]); + // Don't hoist things out of a large switch statement. This often causes + // code to be hoisted that wasn't going to be executed, and increases + // register pressure in a situation where it's likely to matter. + if (Children.size() < 10) + for (unsigned I = 0, E = Children.size(); I != E; ++I) + HoistRegion(Children[I]); } /// IsLICMCandidate - Returns true if the instruction may be a suitable |