revert 132986 to see if the bots go green.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132988 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 21 deletions

diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp
index b43884ebf2..719cd264f6 100644
--- a/lib/CodeGen/BranchFolding.cpp
+++ b/lib/CodeGen/BranchFolding.cpp
@@ -799,22 +799,14 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
 
   // First find blocks with no successors.
   MergePotentials.clear();
-  for (MachineFunction::iterator I = MF.begin(), E = MF.end();
-       I != E && MergePotentials.size() < TailMergeThreshold; ++I) {
-    if (TriedMerging.count(I))
-      continue;
+  for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
     if (I->succ_empty())
       MergePotentials.push_back(MergePotentialsElt(HashEndOfMBB(I), I));
   }
 
-  // If this is a large problem, avoid visiting the same basic blocks
-  // multiple times.
-  if (MergePotentials.size() == TailMergeThreshold)
-    for (unsigned i = 0, e = MergePotentials.size(); i != e; ++i)
-      TriedMerging.insert(MergePotentials[i].getBlock());
-
   // See if we can do any tail merging on those.
-  if (MergePotentials.size() >= 2)
+  if (MergePotentials.size() < TailMergeThreshold &&
+      MergePotentials.size() >= 2)
     MadeChange |= TryTailMergeBlocks(NULL, NULL);
 
   // Look at blocks (IBB) with multiple predecessors (PBB).
@@ -838,17 +830,15 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
 
   for (MachineFunction::iterator I = llvm::next(MF.begin()), E = MF.end();
        I != E; ++I) {
-    if (I->pred_size() >= 2) {
+    if (I->pred_size() >= 2 && I->pred_size() < TailMergeThreshold) {
       SmallPtrSet<MachineBasicBlock *, 8> UniquePreds;
       MachineBasicBlock *IBB = I;
       MachineBasicBlock *PredBB = prior(I);
       MergePotentials.clear();
       for (MachineBasicBlock::pred_iterator P = I->pred_begin(),
                                             E2 = I->pred_end();
-           P != E2 && MergePotentials.size() < TailMergeThreshold; ++P) {
+           P != E2; ++P) {
         MachineBasicBlock *PBB = *P;
-        if (TriedMerging.count(PBB))
-          continue;
         // Skip blocks that loop to themselves, can't tail merge these.
         if (PBB == IBB)
           continue;
@@ -901,12 +891,6 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
           MergePotentials.push_back(MergePotentialsElt(HashEndOfMBB(PBB), *P));
         }
       }
-      // If this is a large problem, avoid visiting the same basic blocks
-      // multiple times.
-      if (MergePotentials.size() == TailMergeThreshold)
-        for (unsigned i = 0, e = MergePotentials.size(); i != e; ++i)
-          TriedMerging.insert(MergePotentials[i].getBlock());
-
       if (MergePotentials.size() >= 2)
         MadeChange |= TryTailMergeBlocks(IBB, PredBB);
       // Reinsert an unconditional branch if needed.