diff options
| -rw-r--r-- | llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp b/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp index 59ec01c7d58..7e44574a6e8 100644 --- a/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp +++ b/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp @@ -19,6 +19,7 @@ #include "llvm/Transforms/Scalar.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Analysis/Dominators.h" +#include "llvm/Analysis/LoopInfo.h" #include "llvm/Function.h" #include "llvm/Instructions.h" #include "llvm/Type.h" @@ -37,6 +38,7 @@ namespace { AU.addPreserved<ImmediateDominators>(); AU.addPreserved<DominatorTree>(); AU.addPreserved<DominanceFrontier>(); + AU.addPreserved<LoopInfo>(); // No loop canonicalization guarantees are broken by this pass. AU.addPreservedID(LoopSimplifyID); @@ -171,5 +173,34 @@ bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P) { NewDFSet.insert(DestBB); DF->addBasicBlock(NewBB, NewDFSet); } + + // Update LoopInfo if it is around. + if (LoopInfo *LI = P->getAnalysisToUpdate<LoopInfo>()) { + // If one or the other blocks were not in a loop, the new block is not + // either, and thus LI doesn't need to be updated. + if (Loop *TIL = LI->getLoopFor(TIBB)) + if (Loop *DestLoop = LI->getLoopFor(DestBB)) { + if (TIL == DestLoop) { + // Both in the same loop, the NewBB joins loop. + DestLoop->addBasicBlockToLoop(NewBB, *LI); + } else if (TIL->contains(DestLoop->getHeader())) { + // Edge from an outer loop to an inner loop. Add to the outer lopo. + TIL->addBasicBlockToLoop(NewBB, *LI); + } else if (DestLoop->contains(TIL->getHeader())) { + // Edge from an inner loop to an outer loop. Add to the outer lopo. + DestLoop->addBasicBlockToLoop(NewBB, *LI); + } else { + // Edge from two loops with no containment relation. Because these + // are natural loops, we know that the destination block must be the + // header of its loop (adding a branch into a loop elsewhere would + // create an irreducible loop). + assert(DestLoop->getHeader() == DestBB && + "Should not create irreducible loops!"); + if (Loop *P = DestLoop->getParentLoop()) + P->addBasicBlockToLoop(NewBB, *LI); + } + } + + } return true; } |
