1 files changed, 36 insertions, 32 deletions
diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp
index 9dec22e..7f98df0 100644
--- a/lib/CodeGen/BranchFolding.cpp
+++ b/lib/CodeGen/BranchFolding.cpp
@@ -358,23 +358,10 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1,
 }
 
 /// ReplaceTailWithBranchTo - Delete the instruction OldInst and everything
-/// after it, replacing it with an unconditional branch to NewDest.  This
-/// returns true if OldInst's block is modified, false if NewDest is modified.
+/// after it, replacing it with an unconditional branch to NewDest.
 void BranchFolder::ReplaceTailWithBranchTo(MachineBasicBlock::iterator OldInst,
                                            MachineBasicBlock *NewDest) {
-  MachineBasicBlock *OldBB = OldInst->getParent();
-
-  // Remove all the old successors of OldBB from the CFG.
-  while (!OldBB->succ_empty())
-    OldBB->removeSuccessor(OldBB->succ_begin());
-
-  // Remove all the dead instructions from the end of OldBB.
-  OldBB->erase(OldInst, OldBB->end());
-
-  // If OldBB isn't immediately before OldBB, insert a branch to it.
-  if (++MachineFunction::iterator(OldBB) != MachineFunction::iterator(NewDest))
-    TII->InsertBranch(*OldBB, NewDest, 0, SmallVector<MachineOperand, 0>());
-  OldBB->addSuccessor(NewDest);
+  TII->ReplaceTailWithBranchTo(OldInst, NewDest);
   ++NumTailMerge;
 }
 
@@ -383,6 +370,9 @@ void BranchFolder::ReplaceTailWithBranchTo(MachineBasicBlock::iterator OldInst,
 /// iterator.  This returns the new MBB.
 MachineBasicBlock *BranchFolder::SplitMBBAt(MachineBasicBlock &CurMBB,
                                             MachineBasicBlock::iterator BBI1) {
+  if (!TII->isLegalToSplitMBBAt(CurMBB, BBI1))
+    return 0;
+
   MachineFunction &MF = *CurMBB.getParent();
 
   // Create the fall-through block.
@@ -443,18 +433,20 @@ static void FixTail(MachineBasicBlock *CurMBB, MachineBasicBlock *SuccBB,
   MachineFunction::iterator I = llvm::next(MachineFunction::iterator(CurMBB));
   MachineBasicBlock *TBB = 0, *FBB = 0;
   SmallVector<MachineOperand, 4> Cond;
+  DebugLoc dl;  // FIXME: this is nowhere
   if (I != MF->end() &&
       !TII->AnalyzeBranch(*CurMBB, TBB, FBB, Cond, true)) {
     MachineBasicBlock *NextBB = I;
     if (TBB == NextBB && !Cond.empty() && !FBB) {
       if (!TII->ReverseBranchCondition(Cond)) {
         TII->RemoveBranch(*CurMBB);
-        TII->InsertBranch(*CurMBB, SuccBB, NULL, Cond);
+        TII->InsertBranch(*CurMBB, SuccBB, NULL, Cond, dl);
         return;
       }
     }
   }
-  TII->InsertBranch(*CurMBB, SuccBB, NULL, SmallVector<MachineOperand, 0>());
+  TII->InsertBranch(*CurMBB, SuccBB, NULL,
+                    SmallVector<MachineOperand, 0>(), dl);
 }
 
 bool
@@ -625,9 +617,10 @@ void BranchFolder::RemoveBlocksWithHash(unsigned CurHash,
 
 /// CreateCommonTailOnlyBlock - None of the blocks to be tail-merged consist
 /// only of the common tail.  Create a block that does by splitting one.
-unsigned BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB,
-                                             unsigned maxCommonTailLength) {
-  unsigned commonTailIndex = 0;
+bool BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB,
+                                             unsigned maxCommonTailLength,
+                                             unsigned &commonTailIndex) {
+  commonTailIndex = 0;
   unsigned TimeEstimate = ~0U;
   for (unsigned i = 0, e = SameTails.size(); i != e; ++i) {
     // Use PredBB if possible; that doesn't require a new branch.
@@ -655,6 +648,11 @@ unsigned BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB,
                << maxCommonTailLength);
 
   MachineBasicBlock *newMBB = SplitMBBAt(*MBB, BBI);
+  if (!newMBB) {
+    DEBUG(dbgs() << "... failed!");
+    return false;
+  }
+
   SameTails[commonTailIndex].setBlock(newMBB);
   SameTails[commonTailIndex].setTailStartPos(newMBB->begin());
 
@@ -662,7 +660,7 @@ unsigned BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB,
   if (PredBB == MBB)
     PredBB = newMBB;
 
-  return commonTailIndex;
+  return true;
 }
 
 // See if any of the blocks in MergePotentials (which all have a common single
@@ -757,7 +755,11 @@ bool BranchFolder::TryTailMergeBlocks(MachineBasicBlock *SuccBB,
          !SameTails[commonTailIndex].tailIsWholeBlock())) {
       // None of the blocks consist entirely of the common tail.
       // Split a block so that one does.
-      commonTailIndex = CreateCommonTailOnlyBlock(PredBB, maxCommonTailLength);
+      if (!CreateCommonTailOnlyBlock(PredBB,
+                                     maxCommonTailLength, commonTailIndex)) {
+        RemoveBlocksWithHash(CurHash, SuccBB, PredBB);
+        continue;
+      }
     }
 
     MachineBasicBlock *MBB = SameTails[commonTailIndex].getBlock();
@@ -874,10 +876,11 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
           }
           // Remove the unconditional branch at the end, if any.
           if (TBB && (Cond.empty() || FBB)) {
+            DebugLoc dl;  // FIXME: this is nowhere
             TII->RemoveBranch(*PBB);
             if (!Cond.empty())
               // reinsert conditional branch only, for now
-              TII->InsertBranch(*PBB, (TBB == IBB) ? FBB : TBB, 0, NewCond);
+              TII->InsertBranch(*PBB, (TBB == IBB) ? FBB : TBB, 0, NewCond, dl);
           }
           MergePotentials.push_back(MergePotentialsElt(HashEndOfMBB(PBB), *P));
         }
@@ -976,6 +979,7 @@ static bool IsBetterFallthrough(MachineBasicBlock *MBB1,
 bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
   bool MadeChange = false;
   MachineFunction &MF = *MBB->getParent();
+  DebugLoc dl;  // FIXME: this is nowhere
 ReoptimizeBlock:
 
   MachineFunction::iterator FallThrough = MBB;
@@ -1027,7 +1031,7 @@ ReoptimizeBlock:
       TII->RemoveBranch(PrevBB);
       PriorCond.clear();
       if (PriorTBB != MBB)
-        TII->InsertBranch(PrevBB, PriorTBB, 0, PriorCond);
+        TII->InsertBranch(PrevBB, PriorTBB, 0, PriorCond, dl);
       MadeChange = true;
       ++NumBranchOpts;
       goto ReoptimizeBlock;
@@ -1066,7 +1070,7 @@ ReoptimizeBlock:
     // the condition is false, remove the uncond second branch.
     if (PriorFBB == MBB) {
       TII->RemoveBranch(PrevBB);
-      TII->InsertBranch(PrevBB, PriorTBB, 0, PriorCond);
+      TII->InsertBranch(PrevBB, PriorTBB, 0, PriorCond, dl);
       MadeChange = true;
       ++NumBranchOpts;
       goto ReoptimizeBlock;
@@ -1079,7 +1083,7 @@ ReoptimizeBlock:
       SmallVector<MachineOperand, 4> NewPriorCond(PriorCond);
       if (!TII->ReverseBranchCondition(NewPriorCond)) {
         TII->RemoveBranch(PrevBB);
-        TII->InsertBranch(PrevBB, PriorFBB, 0, NewPriorCond);
+        TII->InsertBranch(PrevBB, PriorFBB, 0, NewPriorCond, dl);
         MadeChange = true;
         ++NumBranchOpts;
         goto ReoptimizeBlock;
@@ -1116,7 +1120,7 @@ ReoptimizeBlock:
                        << "To make fallthrough to: " << *PriorTBB << "\n");
 
           TII->RemoveBranch(PrevBB);
-          TII->InsertBranch(PrevBB, MBB, 0, NewPriorCond);
+          TII->InsertBranch(PrevBB, MBB, 0, NewPriorCond, dl);
 
           // Move this block to the end of the function.
           MBB->moveAfter(--MF.end());
@@ -1145,7 +1149,7 @@ ReoptimizeBlock:
       SmallVector<MachineOperand, 4> NewCond(CurCond);
       if (!TII->ReverseBranchCondition(NewCond)) {
         TII->RemoveBranch(*MBB);
-        TII->InsertBranch(*MBB, CurFBB, CurTBB, NewCond);
+        TII->InsertBranch(*MBB, CurFBB, CurTBB, NewCond, dl);
         MadeChange = true;
         ++NumBranchOpts;
         goto ReoptimizeBlock;
@@ -1200,7 +1204,7 @@ ReoptimizeBlock:
               PriorFBB = MBB;
             }
             TII->RemoveBranch(PrevBB);
-            TII->InsertBranch(PrevBB, PriorTBB, PriorFBB, PriorCond);
+            TII->InsertBranch(PrevBB, PriorTBB, PriorFBB, PriorCond, dl);
           }
 
           // Iterate through all the predecessors, revectoring each in-turn.
@@ -1226,7 +1230,7 @@ ReoptimizeBlock:
               if (!NewCurUnAnalyzable && NewCurTBB && NewCurTBB == NewCurFBB) {
                 TII->RemoveBranch(*PMBB);
                 NewCurCond.clear();
-                TII->InsertBranch(*PMBB, NewCurTBB, 0, NewCurCond);
+                TII->InsertBranch(*PMBB, NewCurTBB, 0, NewCurCond, dl);
                 MadeChange = true;
                 ++NumBranchOpts;
                 PMBB->CorrectExtraCFGEdges(NewCurTBB, 0, false);
@@ -1246,7 +1250,7 @@ ReoptimizeBlock:
       }
 
       // Add the branch back if the block is more than just an uncond branch.
-      TII->InsertBranch(*MBB, CurTBB, 0, CurCond);
+      TII->InsertBranch(*MBB, CurTBB, 0, CurCond, dl);
     }
   }
 
@@ -1286,7 +1290,7 @@ ReoptimizeBlock:
           if (CurFallsThru) {
             MachineBasicBlock *NextBB = llvm::next(MachineFunction::iterator(MBB));
             CurCond.clear();
-            TII->InsertBranch(*MBB, NextBB, 0, CurCond);
+            TII->InsertBranch(*MBB, NextBB, 0, CurCond, dl);
           }
           MBB->moveAfter(PredBB);
           MadeChange = true;