From cf42ee42b1a5444cd073703ff284ae0a41608227 Mon Sep 17 00:00:00 2001 From: Devang Patel Date: Mon, 2 Mar 2009 23:39:14 +0000 Subject: If branch conditions' one successor is dominating another non-latch successor then this loop's iteration space can not be restricted. In this example block bb5 is always executed. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65902 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/LoopIndexSplit.cpp | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'lib/Transforms/Scalar/LoopIndexSplit.cpp') diff --git a/lib/Transforms/Scalar/LoopIndexSplit.cpp b/lib/Transforms/Scalar/LoopIndexSplit.cpp index 6311e171e0..e93d448cc1 100644 --- a/lib/Transforms/Scalar/LoopIndexSplit.cpp +++ b/lib/Transforms/Scalar/LoopIndexSplit.cpp @@ -532,6 +532,21 @@ bool LoopIndexSplit::updateLoopIterationSpace() { BasicBlock *ExitingBlock = ExitCondition->getParent(); if (!cleanBlock(ExitingBlock)) return false; + // If the merge point for BR is not loop latch then skip this loop. + if (BR->getSuccessor(0) != Latch) { + DominanceFrontier::iterator DF0 = DF->find(BR->getSuccessor(0)); + assert (DF0 != DF->end() && "Unable to find dominance frontier"); + if (!DF0->second.count(Latch)) + return false; + } + + if (BR->getSuccessor(1) != Latch) { + DominanceFrontier::iterator DF1 = DF->find(BR->getSuccessor(1)); + assert (DF1 != DF->end() && "Unable to find dominance frontier"); + if (!DF1->second.count(Latch)) + return false; + } + // Verify that loop exiting block has only two predecessor, where one pred // is split condition block. The other predecessor will become exiting block's // dominator after CFG is updated. TODO : Handle CFG's where exiting block has -- cgit v1.2.3