From c46cfcbbc623ec9f1f1070f4cf55200fdc681980 Mon Sep 17 00:00:00 2001 From: "Duncan P. N. Exon Smith" Date: Tue, 7 Oct 2014 21:19:00 +0000 Subject: LoopUnroll: Create sub-loops in LoopInfo `LoopUnrollPass` says that it preserves `LoopInfo` -- make it so. In particular, tell `LoopInfo` about copies of inner loops when unrolling the outer loop. Conservatively, also tell `ScalarEvolution` to forget about the original versions of these loops, since their inputs may have changed. Fixes PR20987. llvm-svn: 219241 --- llvm/lib/Transforms/Utils/LoopUnroll.cpp | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) (limited to 'llvm/lib/Transforms/Utils/LoopUnroll.cpp') diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp index b1cc76859e9..7b066453cee 100644 --- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp +++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp @@ -301,13 +301,41 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, for (unsigned It = 1; It != Count; ++It) { std::vector NewBlocks; + SmallDenseMap NewLoops; + NewLoops[L] = L; for (LoopBlocksDFS::RPOIterator BB = BlockBegin; BB != BlockEnd; ++BB) { ValueToValueMapTy VMap; BasicBlock *New = CloneBasicBlock(*BB, VMap, "." + Twine(It)); Header->getParent()->getBasicBlockList().push_back(New); - L->addBasicBlockToLoop(New, LI->getBase()); + // Tell LI about New. + if (*BB == Header) { + assert(LI->getLoopFor(*BB) == L && "Header should not be in a sub-loop"); + L->addBasicBlockToLoop(New, LI->getBase()); + } else { + // Figure out which loop New is in. + const Loop *OldLoop = LI->getLoopFor(*BB); + assert(OldLoop && "Should (at least) be in the loop being unrolled!"); + + Loop *&NewLoop = NewLoops[OldLoop]; + if (!NewLoop) { + // Found a new sub-loop. + assert(*BB == OldLoop->getHeader() && + "Header should be first in RPO"); + + Loop *NewLoopParent = NewLoops.lookup(OldLoop->getParentLoop()); + assert(NewLoopParent && + "Expected parent loop before sub-loop in RPO"); + NewLoop = new Loop; + NewLoopParent->addChildLoop(NewLoop); + + // Forget the old loop, since its inputs may have changed. + if (SE) + SE->forgetLoop(OldLoop); + } + NewLoop->addBasicBlockToLoop(New, LI->getBase()); + } if (*BB == Header) // Loop over all of the PHI nodes in the block, changing them to use -- cgit v1.2.3