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diff --git a/contrib/llvm/lib/Transforms/Scalar/LoopDeletion.cpp b/contrib/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
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+++ b/contrib/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
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+//===- LoopDeletion.cpp - Dead Loop Deletion Pass ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Dead Loop Deletion Pass. This pass is responsible
+// for eliminating loops with non-infinite computable trip counts that have no
+// side effects or volatile instructions, and do not contribute to the
+// computation of the function's return value.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "loop-delete"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+using namespace llvm;
+
+STATISTIC(NumDeleted, "Number of loops deleted");
+
+namespace {
+  class LoopDeletion : public LoopPass {
+  public:
+    static char ID; // Pass ID, replacement for typeid
+    LoopDeletion() : LoopPass(ID) {
+      initializeLoopDeletionPass(*PassRegistry::getPassRegistry());
+    }
+
+    // Possibly eliminate loop L if it is dead.
+    bool runOnLoop(Loop *L, LPPassManager &LPM);
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.addRequired<DominatorTree>();
+      AU.addRequired<LoopInfo>();
+      AU.addRequired<ScalarEvolution>();
+      AU.addRequiredID(LoopSimplifyID);
+      AU.addRequiredID(LCSSAID);
+
+      AU.addPreserved<ScalarEvolution>();
+      AU.addPreserved<DominatorTree>();
+      AU.addPreserved<LoopInfo>();
+      AU.addPreservedID(LoopSimplifyID);
+      AU.addPreservedID(LCSSAID);
+    }
+
+  private:
+    bool isLoopDead(Loop *L, SmallVectorImpl<BasicBlock *> &exitingBlocks,
+                    SmallVectorImpl<BasicBlock *> &exitBlocks,
+                    bool &Changed, BasicBlock *Preheader);
+
+  };
+}
+
+char LoopDeletion::ID = 0;
+INITIALIZE_PASS_BEGIN(LoopDeletion, "loop-deletion",
+                "Delete dead loops", false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_DEPENDENCY(LoopInfo)
+INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
+INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
+INITIALIZE_PASS_DEPENDENCY(LCSSA)
+INITIALIZE_PASS_END(LoopDeletion, "loop-deletion",
+                "Delete dead loops", false, false)
+
+Pass *llvm::createLoopDeletionPass() {
+  return new LoopDeletion();
+}
+
+/// isLoopDead - Determined if a loop is dead.  This assumes that we've already
+/// checked for unique exit and exiting blocks, and that the code is in LCSSA
+/// form.
+bool LoopDeletion::isLoopDead(Loop *L,
+                              SmallVectorImpl<BasicBlock *> &exitingBlocks,
+                              SmallVectorImpl<BasicBlock *> &exitBlocks,
+                              bool &Changed, BasicBlock *Preheader) {
+  BasicBlock *exitBlock = exitBlocks[0];
+
+  // Make sure that all PHI entries coming from the loop are loop invariant.
+  // Because the code is in LCSSA form, any values used outside of the loop
+  // must pass through a PHI in the exit block, meaning that this check is
+  // sufficient to guarantee that no loop-variant values are used outside
+  // of the loop.
+  BasicBlock::iterator BI = exitBlock->begin();
+  while (PHINode *P = dyn_cast<PHINode>(BI)) {
+    Value *incoming = P->getIncomingValueForBlock(exitingBlocks[0]);
+
+    // Make sure all exiting blocks produce the same incoming value for the exit
+    // block.  If there are different incoming values for different exiting
+    // blocks, then it is impossible to statically determine which value should
+    // be used.
+    for (unsigned i = 1, e = exitingBlocks.size(); i < e; ++i) {
+      if (incoming != P->getIncomingValueForBlock(exitingBlocks[i]))
+        return false;
+    }
+
+    if (Instruction *I = dyn_cast<Instruction>(incoming))
+      if (!L->makeLoopInvariant(I, Changed, Preheader->getTerminator()))
+        return false;
+
+    ++BI;
+  }
+
+  // Make sure that no instructions in the block have potential side-effects.
+  // This includes instructions that could write to memory, and loads that are
+  // marked volatile.  This could be made more aggressive by using aliasing
+  // information to identify readonly and readnone calls.
+  for (Loop::block_iterator LI = L->block_begin(), LE = L->block_end();
+       LI != LE; ++LI) {
+    for (BasicBlock::iterator BI = (*LI)->begin(), BE = (*LI)->end();
+         BI != BE; ++BI) {
+      if (BI->mayHaveSideEffects())
+        return false;
+    }
+  }
+
+  return true;
+}
+
+/// runOnLoop - Remove dead loops, by which we mean loops that do not impact the
+/// observable behavior of the program other than finite running time.  Note
+/// we do ensure that this never remove a loop that might be infinite, as doing
+/// so could change the halting/non-halting nature of a program.
+/// NOTE: This entire process relies pretty heavily on LoopSimplify and LCSSA
+/// in order to make various safety checks work.
+bool LoopDeletion::runOnLoop(Loop *L, LPPassManager &LPM) {
+  // We can only remove the loop if there is a preheader that we can
+  // branch from after removing it.
+  BasicBlock *preheader = L->getLoopPreheader();
+  if (!preheader)
+    return false;
+
+  // If LoopSimplify form is not available, stay out of trouble.
+  if (!L->hasDedicatedExits())
+    return false;
+
+  // We can't remove loops that contain subloops.  If the subloops were dead,
+  // they would already have been removed in earlier executions of this pass.
+  if (L->begin() != L->end())
+    return false;
+
+  SmallVector<BasicBlock*, 4> exitingBlocks;
+  L->getExitingBlocks(exitingBlocks);
+
+  SmallVector<BasicBlock*, 4> exitBlocks;
+  L->getUniqueExitBlocks(exitBlocks);
+
+  // We require that the loop only have a single exit block.  Otherwise, we'd
+  // be in the situation of needing to be able to solve statically which exit
+  // block will be branched to, or trying to preserve the branching logic in
+  // a loop invariant manner.
+  if (exitBlocks.size() != 1)
+    return false;
+
+  // Finally, we have to check that the loop really is dead.
+  bool Changed = false;
+  if (!isLoopDead(L, exitingBlocks, exitBlocks, Changed, preheader))
+    return Changed;
+
+  // Don't remove loops for which we can't solve the trip count.
+  // They could be infinite, in which case we'd be changing program behavior.
+  ScalarEvolution &SE = getAnalysis<ScalarEvolution>();
+  const SCEV *S = SE.getMaxBackedgeTakenCount(L);
+  if (isa<SCEVCouldNotCompute>(S))
+    return Changed;
+
+  // Now that we know the removal is safe, remove the loop by changing the
+  // branch from the preheader to go to the single exit block.
+  BasicBlock *exitBlock = exitBlocks[0];
+
+  // Because we're deleting a large chunk of code at once, the sequence in which
+  // we remove things is very important to avoid invalidation issues.  Don't
+  // mess with this unless you have good reason and know what you're doing.
+
+  // Tell ScalarEvolution that the loop is deleted. Do this before
+  // deleting the loop so that ScalarEvolution can look at the loop
+  // to determine what it needs to clean up.
+  SE.forgetLoop(L);
+
+  // Connect the preheader directly to the exit block.
+  TerminatorInst *TI = preheader->getTerminator();
+  TI->replaceUsesOfWith(L->getHeader(), exitBlock);
+
+  // Rewrite phis in the exit block to get their inputs from
+  // the preheader instead of the exiting block.
+  BasicBlock *exitingBlock = exitingBlocks[0];
+  BasicBlock::iterator BI = exitBlock->begin();
+  while (PHINode *P = dyn_cast<PHINode>(BI)) {
+    int j = P->getBasicBlockIndex(exitingBlock);
+    assert(j >= 0 && "Can't find exiting block in exit block's phi node!");
+    P->setIncomingBlock(j, preheader);
+    for (unsigned i = 1; i < exitingBlocks.size(); ++i)
+      P->removeIncomingValue(exitingBlocks[i]);
+    ++BI;
+  }
+
+  // Update the dominator tree and remove the instructions and blocks that will
+  // be deleted from the reference counting scheme.
+  DominatorTree &DT = getAnalysis<DominatorTree>();
+  SmallVector<DomTreeNode*, 8> ChildNodes;
+  for (Loop::block_iterator LI = L->block_begin(), LE = L->block_end();
+       LI != LE; ++LI) {
+    // Move all of the block's children to be children of the preheader, which
+    // allows us to remove the domtree entry for the block.
+    ChildNodes.insert(ChildNodes.begin(), DT[*LI]->begin(), DT[*LI]->end());
+    for (SmallVectorImpl<DomTreeNode *>::iterator DI = ChildNodes.begin(),
+         DE = ChildNodes.end(); DI != DE; ++DI) {
+      DT.changeImmediateDominator(*DI, DT[preheader]);
+    }
+
+    ChildNodes.clear();
+    DT.eraseNode(*LI);
+
+    // Remove the block from the reference counting scheme, so that we can
+    // delete it freely later.
+    (*LI)->dropAllReferences();
+  }
+
+  // Erase the instructions and the blocks without having to worry
+  // about ordering because we already dropped the references.
+  // NOTE: This iteration is safe because erasing the block does not remove its
+  // entry from the loop's block list.  We do that in the next section.
+  for (Loop::block_iterator LI = L->block_begin(), LE = L->block_end();
+       LI != LE; ++LI)
+    (*LI)->eraseFromParent();
+
+  // Finally, the blocks from loopinfo.  This has to happen late because
+  // otherwise our loop iterators won't work.
+  LoopInfo &loopInfo = getAnalysis<LoopInfo>();
+  SmallPtrSet<BasicBlock*, 8> blocks;
+  blocks.insert(L->block_begin(), L->block_end());
+  for (SmallPtrSet<BasicBlock*,8>::iterator I = blocks.begin(),
+       E = blocks.end(); I != E; ++I)
+    loopInfo.removeBlock(*I);
+
+  // The last step is to inform the loop pass manager that we've
+  // eliminated this loop.
+  LPM.deleteLoopFromQueue(L);
+  Changed = true;
+
+  ++NumDeleted;
+
+  return Changed;
+}