1 files changed, 3 insertions, 165 deletions

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 8e1fb98..8dbc808 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -78,166 +78,6 @@ static void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred,
     PN->addIncoming(PN->getIncomingValueForBlock(ExistPred), NewPred);
 }
 
-/// CanPropagatePredecessorsForPHIs - Return true if we can fold BB, an
-/// almost-empty BB ending in an unconditional branch to Succ, into succ.
-///
-/// Assumption: Succ is the single successor for BB.
-///
-static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
-  assert(*succ_begin(BB) == Succ && "Succ is not successor of BB!");
-
-  DEBUG(errs() << "Looking to fold " << BB->getName() << " into " 
-        << Succ->getName() << "\n");
-  // Shortcut, if there is only a single predecessor it must be BB and merging
-  // is always safe
-  if (Succ->getSinglePredecessor()) return true;
-
-  // Make a list of the predecessors of BB
-  typedef SmallPtrSet<BasicBlock*, 16> BlockSet;
-  BlockSet BBPreds(pred_begin(BB), pred_end(BB));
-
-  // Use that list to make another list of common predecessors of BB and Succ
-  BlockSet CommonPreds;
-  for (pred_iterator PI = pred_begin(Succ), PE = pred_end(Succ);
-        PI != PE; ++PI)
-    if (BBPreds.count(*PI))
-      CommonPreds.insert(*PI);
-
-  // Shortcut, if there are no common predecessors, merging is always safe
-  if (CommonPreds.empty())
-    return true;
-  
-  // Look at all the phi nodes in Succ, to see if they present a conflict when
-  // merging these blocks
-  for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
-    PHINode *PN = cast<PHINode>(I);
-
-    // If the incoming value from BB is again a PHINode in
-    // BB which has the same incoming value for *PI as PN does, we can
-    // merge the phi nodes and then the blocks can still be merged
-    PHINode *BBPN = dyn_cast<PHINode>(PN->getIncomingValueForBlock(BB));
-    if (BBPN && BBPN->getParent() == BB) {
-      for (BlockSet::iterator PI = CommonPreds.begin(), PE = CommonPreds.end();
-            PI != PE; PI++) {
-        if (BBPN->getIncomingValueForBlock(*PI) 
-              != PN->getIncomingValueForBlock(*PI)) {
-          DEBUG(errs() << "Can't fold, phi node " << PN->getName() << " in " 
-                << Succ->getName() << " is conflicting with " 
-                << BBPN->getName() << " with regard to common predecessor "
-                << (*PI)->getName() << "\n");
-          return false;
-        }
-      }
-    } else {
-      Value* Val = PN->getIncomingValueForBlock(BB);
-      for (BlockSet::iterator PI = CommonPreds.begin(), PE = CommonPreds.end();
-            PI != PE; PI++) {
-        // See if the incoming value for the common predecessor is equal to the
-        // one for BB, in which case this phi node will not prevent the merging
-        // of the block.
-        if (Val != PN->getIncomingValueForBlock(*PI)) {
-          DEBUG(errs() << "Can't fold, phi node " << PN->getName() << " in " 
-                << Succ->getName() << " is conflicting with regard to common "
-                << "predecessor " << (*PI)->getName() << "\n");
-          return false;
-        }
-      }
-    }
-  }
-
-  return true;
-}
-
-/// TryToSimplifyUncondBranchFromEmptyBlock - BB contains an unconditional
-/// branch to Succ, and contains no instructions other than PHI nodes and the
-/// branch.  If possible, eliminate BB.
-static bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
-                                                    BasicBlock *Succ) {
-  // Check to see if merging these blocks would cause conflicts for any of the
-  // phi nodes in BB or Succ. If not, we can safely merge.
-  if (!CanPropagatePredecessorsForPHIs(BB, Succ)) return false;
-
-  // Check for cases where Succ has multiple predecessors and a PHI node in BB
-  // has uses which will not disappear when the PHI nodes are merged.  It is
-  // possible to handle such cases, but difficult: it requires checking whether
-  // BB dominates Succ, which is non-trivial to calculate in the case where
-  // Succ has multiple predecessors.  Also, it requires checking whether
-  // constructing the necessary self-referential PHI node doesn't intoduce any
-  // conflicts; this isn't too difficult, but the previous code for doing this
-  // was incorrect.
-  //
-  // Note that if this check finds a live use, BB dominates Succ, so BB is
-  // something like a loop pre-header (or rarely, a part of an irreducible CFG);
-  // folding the branch isn't profitable in that case anyway.
-  if (!Succ->getSinglePredecessor()) {
-    BasicBlock::iterator BBI = BB->begin();
-    while (isa<PHINode>(*BBI)) {
-      for (Value::use_iterator UI = BBI->use_begin(), E = BBI->use_end();
-           UI != E; ++UI) {
-        if (PHINode* PN = dyn_cast<PHINode>(*UI)) {
-          if (PN->getIncomingBlock(UI) != BB)
-            return false;
-        } else {
-          return false;
-        }
-      }
-      ++BBI;
-    }
-  }
-
-  DEBUG(errs() << "Killing Trivial BB: \n" << *BB);
-  
-  if (isa<PHINode>(Succ->begin())) {
-    // If there is more than one pred of succ, and there are PHI nodes in
-    // the successor, then we need to add incoming edges for the PHI nodes
-    //
-    const SmallVector<BasicBlock*, 16> BBPreds(pred_begin(BB), pred_end(BB));
-    
-    // Loop over all of the PHI nodes in the successor of BB.
-    for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
-      PHINode *PN = cast<PHINode>(I);
-      Value *OldVal = PN->removeIncomingValue(BB, false);
-      assert(OldVal && "No entry in PHI for Pred BB!");
-      
-      // If this incoming value is one of the PHI nodes in BB, the new entries
-      // in the PHI node are the entries from the old PHI.
-      if (isa<PHINode>(OldVal) && cast<PHINode>(OldVal)->getParent() == BB) {
-        PHINode *OldValPN = cast<PHINode>(OldVal);
-        for (unsigned i = 0, e = OldValPN->getNumIncomingValues(); i != e; ++i)
-          // Note that, since we are merging phi nodes and BB and Succ might
-          // have common predecessors, we could end up with a phi node with
-          // identical incoming branches. This will be cleaned up later (and
-          // will trigger asserts if we try to clean it up now, without also
-          // simplifying the corresponding conditional branch).
-          PN->addIncoming(OldValPN->getIncomingValue(i),
-                          OldValPN->getIncomingBlock(i));
-      } else {
-        // Add an incoming value for each of the new incoming values.
-        for (unsigned i = 0, e = BBPreds.size(); i != e; ++i)
-          PN->addIncoming(OldVal, BBPreds[i]);
-      }
-    }
-  }
-  
-  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();
-    }
-  }
-    
-  // Everything that jumped to BB now goes to Succ.
-  BB->replaceAllUsesWith(Succ);
-  if (!Succ->hasName()) Succ->takeName(BB);
-  BB->eraseFromParent();              // Delete the old basic block.
-  return true;
-}
 
 /// GetIfCondition - Given a basic block (BB) with two predecessors (and
 /// presumably PHI nodes in it), check to see if the merge at this block is due
@@ -1217,7 +1057,7 @@ static bool FoldCondBranchOnPHI(BranchInst *BI) {
           }
           
           // Check for trivial simplification.
-          if (Constant *C = ConstantFoldInstruction(N, BB->getContext())) {
+          if (Constant *C = ConstantFoldInstruction(N)) {
             TranslateMap[BBI] = C;
             delete N;   // Constant folded away, don't need actual inst
           } else {
@@ -1983,13 +1823,11 @@ bool llvm::SimplifyCFG(BasicBlock *BB) {
     if (BI->isUnconditional()) {
       BasicBlock::iterator BBI = BB->getFirstNonPHI();
 
-      BasicBlock *Succ = BI->getSuccessor(0);
       // Ignore dbg intrinsics.
       while (isa<DbgInfoIntrinsic>(BBI))
         ++BBI;
-      if (BBI->isTerminator() &&  // Terminator is the only non-phi instruction!
-          Succ != BB)             // Don't hurt infinite loops!
-        if (TryToSimplifyUncondBranchFromEmptyBlock(BB, Succ))
+      if (BBI->isTerminator()) // Terminator is the only non-phi instruction!
+        if (TryToSimplifyUncondBranchFromEmptyBlock(BB))
           return true;
       
     } else {  // Conditional branch