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| author | Owen Anderson <resistor@mac.com> | 2008-08-26 22:07:42 +0000 |
|---|---|---|
| committer | Owen Anderson <resistor@mac.com> | 2008-08-26 22:07:42 +0000 |
| commit | 516eb1c1396bc0a2b35573e58c567d6092ed5fd0 (patch) | |
| tree | 3883346488deb26cd7b951ad7568a7e3378bcdeb /lib/Transforms/Scalar | |
| parent | 3200d92947cd64f82ca748d65d1e58c3d45f440f (diff) | |
| download | external_llvm-516eb1c1396bc0a2b35573e58c567d6092ed5fd0.zip external_llvm-516eb1c1396bc0a2b35573e58c567d6092ed5fd0.tar.gz external_llvm-516eb1c1396bc0a2b35573e58c567d6092ed5fd0.tar.bz2 | |
Put a heuristic in place to prevent GVN from falling into bad cases with massively complicated CFGs.
This speeds up a particular testcase from 12+ hours to 5 seconds with little perceptible loss of quality.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55391 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/Scalar')
| -rw-r--r-- | lib/Transforms/Scalar/GVN.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp index 272ad1b..42fbc78 100644 --- a/lib/Transforms/Scalar/GVN.cpp +++ b/lib/Transforms/Scalar/GVN.cpp @@ -862,6 +862,12 @@ bool GVN::processNonLocalLoad(LoadInst* L, DenseMap<BasicBlock*, Value*> deps; MD.getNonLocalDependency(L, deps); + // If we had to process more than one hundred blocks to find the + // dependencies, this load isn't worth worrying about. Optimizing + // it will be too expensive. + if (deps.size() > 100) + return false; + DenseMap<BasicBlock*, Value*> repl; // Filter out useless results (non-locals, etc) |