diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp index 600061de354..09f4976f100 100644 --- a/lib/Transforms/Scalar/LoopUnswitch.cpp +++ b/lib/Transforms/Scalar/LoopUnswitch.cpp @@ -34,6 +34,7 @@ #include "llvm/Analysis/LoopInfo.h" #include "llvm/Transforms/Utils/Cloning.h" #include "llvm/Transforms/Utils/Local.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/ADT/Statistic.h" #include "llvm/Support/Debug.h" #include "llvm/Support/CommandLine.h" @@ -255,6 +256,8 @@ bool LoopUnswitch::visitLoop(Loop *L) { // loop. for (Loop::block_iterator I = L->block_begin(), E = L->block_end(); I != E; ++I) { + for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end(); + BBI != E; ++BBI) TerminatorInst *TI = (*I)->getTerminator(); // FIXME: Handle invariant select instructions. @@ -415,7 +418,27 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond, // Split this block now, so that the loop maintains its exit block. assert(!L->contains(ExitBlock) && "Exit block is in the loop?"); - BasicBlock *NewExit = SplitBlock(ExitBlock, true); + BasicBlock *NewExit; + if (BasicBlock *SinglePred = ExitBlock->getSinglePredecessor()) { + assert(SinglePred == L->getLoopLatch() && "Unexpected case"); + NewExit = SplitBlock(ExitBlock, true); + } else { + // Otherwise, this is a critical edge. Split block would split the wrong + // edge here, so we use SplitCriticalEdge, which allows us to specify the + // edge to split, not just the block. + TerminatorInst *LatchTerm = L->getLoopLatch()->getTerminator(); + unsigned SuccNum = 0; + for (unsigned i = 0, e = LatchTerm->getNumSuccessors(); ; ++i) { + assert(i != e && "Didn't find edge?"); + if (LatchTerm->getSuccessor(i) == ExitBlock) { + SuccNum = i; + break; + } + } + SplitCriticalEdge(LatchTerm, SuccNum, this); + NewExit = LatchTerm->getSuccessor(SuccNum); + assert(NewExit != ExitBlock && "Edge not split!"); + } // Okay, now we have a position to branch from and a position to branch to, // insert the new conditional branch.