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diff --git a/contrib/llvm/lib/Transforms/Scalar/ADCE.cpp b/contrib/llvm/lib/Transforms/Scalar/ADCE.cpp
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+++ b/contrib/llvm/lib/Transforms/Scalar/ADCE.cpp
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+//===- DCE.cpp - Code to perform dead code elimination --------------------===//
+//
+//                     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 Aggressive Dead Code Elimination pass.  This pass
+// optimistically assumes that all instructions are dead until proven otherwise,
+// allowing it to eliminate dead computations that other DCE passes do not 
+// catch, particularly involving loop computations.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "adce"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/InstIterator.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+using namespace llvm;
+
+STATISTIC(NumRemoved, "Number of instructions removed");
+
+namespace {
+  struct ADCE : public FunctionPass {
+    static char ID; // Pass identification, replacement for typeid
+    ADCE() : FunctionPass(&ID) {}
+    
+    virtual bool runOnFunction(Function& F);
+    
+    virtual void getAnalysisUsage(AnalysisUsage& AU) const {
+      AU.setPreservesCFG();
+    }
+    
+  };
+}
+
+char ADCE::ID = 0;
+static RegisterPass<ADCE> X("adce", "Aggressive Dead Code Elimination");
+
+bool ADCE::runOnFunction(Function& F) {
+  SmallPtrSet<Instruction*, 128> alive;
+  SmallVector<Instruction*, 128> worklist;
+  
+  // Collect the set of "root" instructions that are known live.
+  for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
+    if (isa<TerminatorInst>(I.getInstructionIterator()) ||
+        isa<DbgInfoIntrinsic>(I.getInstructionIterator()) ||
+        I->mayHaveSideEffects()) {
+      alive.insert(I.getInstructionIterator());
+      worklist.push_back(I.getInstructionIterator());
+    }
+  
+  // Propagate liveness backwards to operands.
+  while (!worklist.empty()) {
+    Instruction* curr = worklist.pop_back_val();
+    
+    for (Instruction::op_iterator OI = curr->op_begin(), OE = curr->op_end();
+         OI != OE; ++OI)
+      if (Instruction* Inst = dyn_cast<Instruction>(OI))
+        if (alive.insert(Inst))
+          worklist.push_back(Inst);
+  }
+  
+  // The inverse of the live set is the dead set.  These are those instructions
+  // which have no side effects and do not influence the control flow or return
+  // value of the function, and may therefore be deleted safely.
+  // NOTE: We reuse the worklist vector here for memory efficiency.
+  for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
+    if (!alive.count(I.getInstructionIterator())) {
+      worklist.push_back(I.getInstructionIterator());
+      I->dropAllReferences();
+    }
+  
+  for (SmallVector<Instruction*, 1024>::iterator I = worklist.begin(),
+       E = worklist.end(); I != E; ++I) {
+    NumRemoved++;
+    (*I)->eraseFromParent();
+  }
+
+  return !worklist.empty();
+}
+
+FunctionPass *llvm::createAggressiveDCEPass() {
+  return new ADCE();
+}