vendor/llvm/llvm-r114020

1 files changed, 8 insertions, 17 deletions

diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp
index ec625b4cbb28f..093083a630cf3 100644
--- a/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -97,23 +97,13 @@ bool llvm::DeleteDeadPHIs(BasicBlock *BB) {
 /// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,
 /// if possible.  The return value indicates success or failure.
 bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, Pass *P) {
-  pred_iterator PI(pred_begin(BB)), PE(pred_end(BB));
-  // Can't merge the entry block.  Don't merge away blocks who have their
-  // address taken: this is a bug if the predecessor block is the entry node
-  // (because we'd end up taking the address of the entry) and undesirable in
-  // any case.
-  if (pred_begin(BB) == pred_end(BB) ||
-      BB->hasAddressTaken()) return false;
+  // Don't merge away blocks who have their address taken.
+  if (BB->hasAddressTaken()) return false;
   
-  BasicBlock *PredBB = *PI++;
-  for (; PI != PE; ++PI)  // Search all predecessors, see if they are all same
-    if (*PI != PredBB) {
-      PredBB = 0;       // There are multiple different predecessors...
-      break;
-    }
-  
-  // Can't merge if there are multiple predecessors.
+  // Can't merge if there are multiple predecessors, or no predecessors.
+  BasicBlock *PredBB = BB->getUniquePredecessor();
   if (!PredBB) return false;
+
   // Don't break self-loops.
   if (PredBB == BB) return false;
   // Don't break invokes.
@@ -267,7 +257,7 @@ void llvm::RemoveSuccessor(TerminatorInst *TI, unsigned SuccNum) {
   case Instruction::Switch:    // Should remove entry
   default:
   case Instruction::Ret:       // Cannot happen, has no successors!
-    llvm_unreachable("Unhandled terminator instruction type in RemoveSuccessor!");
+    llvm_unreachable("Unhandled terminator inst type in RemoveSuccessor!");
   }
 
   if (NewTI)   // If it's a different instruction, replace.
@@ -421,7 +411,8 @@ BasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB,
   DominatorTree *DT = P ? P->getAnalysisIfAvailable<DominatorTree>() : 0;
   if (DT)
     DT->splitBlock(NewBB);
-  if (DominanceFrontier *DF = P ? P->getAnalysisIfAvailable<DominanceFrontier>():0)
+  if (DominanceFrontier *DF =
+        P ? P->getAnalysisIfAvailable<DominanceFrontier>() : 0)
     DF->splitBlock(NewBB);
 
   // Insert a new PHI node into NewBB for every PHI node in BB and that new PHI