From c2fc1fec6c8c5360828aa778e8fcc446bb9c6ae9 Mon Sep 17 00:00:00 2001 From: Nick Lewycky Date: Sat, 19 Sep 2009 19:00:06 +0000 Subject: 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 --- lib/Analysis/SparsePropagation.cpp | 3 +++ 1 file changed, 3 insertions(+) (limited to 'lib/Analysis/SparsePropagation.cpp') 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()) -- cgit v1.2.3