From 0e747beb3cfc48ebcb0a2f8b962f0d0de525d979 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Fri, 30 Oct 2009 23:15:43 +0000 Subject: [PATCH] Add a comment about a missed opportunity. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85635 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Utils/SimplifyCFG.cpp | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp index 859b8756666..8e1fb98b704 100644 --- a/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/lib/Transforms/Utils/SimplifyCFG.cpp @@ -1753,8 +1753,13 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { /// nodes in this block. This doesn't try to be clever about PHI nodes /// which differ only in the order of the incoming values, but instcombine /// orders them so it usually won't matter. +/// static bool EliminateDuplicatePHINodes(BasicBlock *BB) { bool Changed = false; + + // This implementation doesn't currently consider undef operands + // specially. Theroetically, two phis which are identical except for + // one having an undef where the other doesn't could be collapsed. // Map from PHI hash values to PHI nodes. If multiple PHIs have // the same hash value, the element is the first PHI in the -- 2.34.1