From 3ef9838f89617fc471b6b84a64c7af824a070e50 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Tue, 8 Feb 2011 00:55:13 +0000 Subject: [PATCH] Don't split any loop backedges, including backedges of loops other than the active loop. This is generally desirable, and it avoids trouble in situations such as the testcase in PR9123, though the failure mode depends on use-list order, so it is infeasible to test. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125065 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/LoopStrengthReduce.cpp | 32 +++++++++++++++------------- 1 file changed, 17 insertions(+), 15 deletions(-) diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index d431b6815c4..01dcfaf0652 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -3544,21 +3544,23 @@ void LSRInstance::RewriteForPHI(PHINode *PN, // is the canonical backedge for this loop, which complicates post-inc // users. if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 && - !isa(BB->getTerminator()) && - (PN->getParent() != L->getHeader() || !L->contains(BB))) { - // Split the critical edge. - BasicBlock *NewBB = SplitCriticalEdge(BB, PN->getParent(), P); - - // If PN is outside of the loop and BB is in the loop, we want to - // move the block to be immediately before the PHI block, not - // immediately after BB. - if (L->contains(BB) && !L->contains(PN)) - NewBB->moveBefore(PN->getParent()); - - // Splitting the edge can reduce the number of PHI entries we have. - e = PN->getNumIncomingValues(); - BB = NewBB; - i = PN->getBasicBlockIndex(BB); + !isa(BB->getTerminator())) { + Loop *PNLoop = LI.getLoopFor(PN->getParent()); + if (!PNLoop || PN->getParent() != PNLoop->getHeader()) { + // Split the critical edge. + BasicBlock *NewBB = SplitCriticalEdge(BB, PN->getParent(), P); + + // If PN is outside of the loop and BB is in the loop, we want to + // move the block to be immediately before the PHI block, not + // immediately after BB. + if (L->contains(BB) && !L->contains(PN)) + NewBB->moveBefore(PN->getParent()); + + // Splitting the edge can reduce the number of PHI entries we have. + e = PN->getNumIncomingValues(); + BB = NewBB; + i = PN->getBasicBlockIndex(BB); + } } std::pair::iterator, bool> Pair = -- 2.11.0