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| author | Nick Lewycky <nicholas@mxc.ca> | 2009-09-19 19:00:06 +0000 |
|---|---|---|
| committer | Nick Lewycky <nicholas@mxc.ca> | 2009-09-19 19:00:06 +0000 |
| commit | c2fc1fec6c8c5360828aa778e8fcc446bb9c6ae9 (patch) | |
| tree | 96596f46643119cff89413e4ec82a86baa0eafef /lib/Analysis/SparsePropagation.cpp | |
| parent | a460beb5cdc1cf05da3b22a39fd2b3107ea2e2fe (diff) | |
Add a comment explaining why you would ever want to do this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82319 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Analysis/SparsePropagation.cpp')
| -rw-r--r-- | lib/Analysis/SparsePropagation.cpp | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/lib/Analysis/SparsePropagation.cpp b/lib/Analysis/SparsePropagation.cpp index 8a74745dd3..b7844f0227 100644 --- a/lib/Analysis/SparsePropagation.cpp +++ b/lib/Analysis/SparsePropagation.cpp @@ -223,6 +223,9 @@ void SparseSolver::visitTerminatorInst(TerminatorInst &TI) { } void SparseSolver::visitPHINode(PHINode &PN) { + // The lattice function may store more information on a PHINode than could be + // computed from its incoming values. For example, SSI form stores its sigma + // functions as PHINodes with a single incoming value. if (LatticeFunc->IsSpecialCasedPHI(&PN)) { LatticeVal IV = LatticeFunc->ComputeInstructionState(PN, *this); if (IV != LatticeFunc->getUntrackedVal()) |