Temporarily revert r134057: "Let simplify cfg simplify bb with only debug and

lifetime intrinsics" due to buildbot failures.

llvm-svn: 134071

1 files changed, 10 insertions, 12 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 00469454851..b1dd733ffe5 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -536,9 +536,9 @@ static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
 
 /// TryToSimplifyUncondBranchFromEmptyBlock - BB is known to contain an
 /// unconditional branch, and contains no instructions other than PHI nodes,
-/// potential side-effect free intrinsics and the branch.  If possible,
-/// eliminate BB by rewriting all the predecessors to branch to the successor
-/// block and return true.  If we can't transform, return false.
+/// potential debug intrinsics and the branch.  If possible, eliminate BB by
+/// rewriting all the predecessors to branch to the successor block and return
+/// true.  If we can't transform, return false.
 bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB) {
   assert(BB != &BB->getParent()->getEntryBlock() &&
          "TryToSimplifyUncondBranchFromEmptyBlock called on entry block!");
@@ -613,15 +613,13 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB) {
     }
   }
   
-  if (Succ->getSinglePredecessor()) {
-    // BB is the only predecessor of Succ, so Succ will end up with exactly
-    // the same predecessors BB had.
-
-    // Copy over any phi, debug or lifetime instruction.
-    BB->getTerminator()->eraseFromParent();
-    Succ->getInstList().splice(Succ->begin(), BB->getInstList());
-  } else {
-    while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
+  while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
+    if (Succ->getSinglePredecessor()) {
+      // BB is the only predecessor of Succ, so Succ will end up with exactly
+      // the same predecessors BB had.
+      Succ->getInstList().splice(Succ->begin(),
+                                 BB->getInstList(), BB->begin());
+    } else {
       // We explicitly check for such uses in CanPropagatePredecessorsForPHIs.
       assert(PN->use_empty() && "There shouldn't be any uses here!");
       PN->eraseFromParent();