From 33e7bc00293cad9c4e4fe85d74fbd085c487dfc0 Mon Sep 17 00:00:00 2001 From: Wei Mi Date: Thu, 4 Feb 2016 19:17:33 +0000 Subject: [PATCH] Fix a regression for r259736. When SCEV expansion tries to reuse an existing value, it is needed to ensure that using the Value at the InsertPt will not break LCSSA. The fix adds a check that InsertPt is either inside the candidate Value's parent loop, or the candidate Value's parent loop is nullptr. llvm-svn: 259815 --- llvm/lib/Analysis/ScalarEvolutionExpander.cpp | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp index f95e191..86cfe2d 100644 --- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp @@ -1652,10 +1652,17 @@ Value *SCEVExpander::expand(const SCEV *S) { // If S is scConstant, it may be worse to reuse an existing Value. if (S->getSCEVType() != scConstant && Set) { // Choose a Value from the set which dominates the insertPt. + // insertPt should be inside the Value's parent loop so as not to break + // the LCSSA form. for (auto const &Ent : *Set) { - if (Ent && isa(Ent) && S->getType() == Ent->getType() && - cast(Ent)->getFunction() == InsertPt->getFunction() && - SE.DT.dominates(cast(Ent), InsertPt)) { + Instruction *EntInst = nullptr; + if (Ent && isa(Ent) && + (EntInst = cast(Ent)) && + S->getType() == Ent->getType() && + EntInst->getFunction() == InsertPt->getFunction() && + SE.DT.dominates(EntInst, InsertPt) && + (SE.LI.getLoopFor(EntInst->getParent()) == nullptr || + SE.LI.getLoopFor(EntInst->getParent())->contains(InsertPt))) { V = Ent; break; } -- 2.7.4