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diff --git a/lib/Analysis/LoadValueNumbering.cpp b/lib/Analysis/LoadValueNumbering.cpp
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+//===- LoadValueNumbering.cpp - Load Value #'ing Implementation -*- C++ -*-===//
+//
+// This file implements a value numbering pass that value #'s load instructions.
+// To do this, it finds lexically identical load instructions, and uses alias
+// analysis to determine which loads are guaranteed to produce the same value.
+//
+// This pass builds off of another value numbering pass to implement value
+// numbering for non-load instructions.  It uses Alias Analysis so that it can
+// disambiguate the load instructions.  The more powerful these base analyses
+// are, the more powerful the resultant analysis will be.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/LoadValueNumbering.h"
+#include "llvm/Analysis/ValueNumbering.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Pass.h"
+#include "llvm/iMemory.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Support/CFG.h"
+#include <algorithm>
+#include <set>
+
+namespace {
+  // FIXME: This should not be a functionpass.
+  struct LoadVN : public FunctionPass, public ValueNumbering {
+    
+    /// Pass Implementation stuff.  This doesn't do any analysis.
+    ///
+    bool runOnFunction(Function &) { return false; }
+    
+    /// getAnalysisUsage - Does not modify anything.  It uses Value Numbering
+    /// and Alias Analysis.
+    ///
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+    
+    /// getEqualNumberNodes - Return nodes with the same value number as the
+    /// specified Value.  This fills in the argument vector with any equal
+    /// values.
+    ///
+    virtual void getEqualNumberNodes(Value *V1,
+                                     std::vector<Value*> &RetVals) const;
+  private:
+    /// haveEqualValueNumber - Given two load instructions, determine if they
+    /// both produce the same value on every execution of the program, assuming
+    /// that their source operands always give the same value.  This uses the
+    /// AliasAnalysis implementation to invalidate loads when stores or function
+    /// calls occur that could modify the value produced by the load.
+    ///
+    bool haveEqualValueNumber(LoadInst *LI, LoadInst *LI2, AliasAnalysis &AA,
+                              DominatorSet &DomSetInfo) const;
+  };
+
+  // Register this pass...
+  RegisterOpt<LoadVN> X("load-vn", "Load Value Numbering");
+
+  // Declare that we implement the ValueNumbering interface
+  RegisterAnalysisGroup<ValueNumbering, LoadVN> Y;
+}
+
+
+
+Pass *createLoadValueNumberingPass() { return new LoadVN(); }
+
+
+/// getAnalysisUsage - Does not modify anything.  It uses Value Numbering and
+/// Alias Analysis.
+///
+void LoadVN::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesAll();
+  AU.addRequired<AliasAnalysis>();
+  AU.addRequired<ValueNumbering>();
+  AU.addRequired<DominatorSet>();
+}
+
+// getEqualNumberNodes - Return nodes with the same value number as the
+// specified Value.  This fills in the argument vector with any equal values.
+//
+void LoadVN::getEqualNumberNodes(Value *V,
+                                 std::vector<Value*> &RetVals) const {
+
+  if (LoadInst *LI = dyn_cast<LoadInst>(V)) {
+    // If we have a load instruction find all of the load instructions that use
+    // the same source operand.  We implement this recursively, because there
+    // could be a load of a load of a load that are all identical.  We are
+    // guaranteed that this cannot be an infinite recursion because load
+    // instructions would have to pass through a PHI node in order for there to
+    // be a cycle.  The PHI node would be handled by the else case here,
+    // breaking the infinite recursion.
+    //
+    std::vector<Value*> PointerSources;
+    getEqualNumberNodes(LI->getOperand(0), PointerSources);
+    PointerSources.push_back(LI->getOperand(0));
+
+    Function *F = LI->getParent()->getParent();
+
+    // Now that we know the set of equivalent source pointers for the load
+    // instruction, look to see if there are any load candiates that are
+    // identical.
+    //
+    std::vector<LoadInst*> CandidateLoads;
+    while (!PointerSources.empty()) {
+      Value *Source = PointerSources.back();
+      PointerSources.pop_back();                // Get a source pointer...
+
+      for (Value::use_iterator UI = Source->use_begin(), UE = Source->use_end();
+           UI != UE; ++UI)
+        if (LoadInst *Cand = dyn_cast<LoadInst>(*UI))  // Is a load of source?
+          if (Cand->getParent()->getParent() == F &&   // In the same function?
+              Cand != LI)                              // Not LI itself?
+            CandidateLoads.push_back(Cand);     // Got one...
+    }
+
+    // Remove duplicates from the CandidateLoads list because alias analysis
+    // processing may be somewhat expensive and we don't want to do more work
+    // than neccesary.
+    //
+    std::sort(CandidateLoads.begin(), CandidateLoads.end());
+    CandidateLoads.erase(std::unique(CandidateLoads.begin(),
+                                     CandidateLoads.end()),
+                         CandidateLoads.end());
+
+    // Get Alias Analysis...
+    AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
+    DominatorSet &DomSetInfo = getAnalysis<DominatorSet>();
+    
+    // Loop over all of the candindate loads.  If they are not invalidated by
+    // stores or calls between execution of them and LI, then add them to
+    // RetVals.
+    for (unsigned i = 0, e = CandidateLoads.size(); i != e; ++i)
+      if (haveEqualValueNumber(LI, CandidateLoads[i], AA, DomSetInfo))
+        RetVals.push_back(CandidateLoads[i]);
+    
+  } else {
+    // Make sure passmanager doesn't try to fulfill our request with ourself!
+    assert(&getAnalysis<ValueNumbering>() != (ValueNumbering*)this &&
+           "getAnalysis() returned this!");
+
+    // Not a load instruction?  Just chain to the base value numbering
+    // implementation to satisfy the request...
+    return getAnalysis<ValueNumbering>().getEqualNumberNodes(V, RetVals);
+  }
+}
+
+// CheckForInvalidatingInst - Return true if BB or any of the predecessors of BB
+// (until DestBB) contain an instruction that might invalidate Ptr.
+//
+static bool CheckForInvalidatingInst(BasicBlock *BB, BasicBlock *DestBB,
+                                     Value *Ptr, AliasAnalysis &AA,
+                                     std::set<BasicBlock*> &VisitedSet) {
+  // Found the termination point!
+  if (BB == DestBB || VisitedSet.count(BB)) return false;
+
+  // Avoid infinite recursion!
+  VisitedSet.insert(BB);
+
+  // Can this basic block modify Ptr?
+  if (AA.canBasicBlockModify(*BB, Ptr))
+    return true;
+
+  // Check all of our predecessor blocks...
+  for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI)
+    if (CheckForInvalidatingInst(*PI, DestBB, Ptr, AA, VisitedSet))
+      return true;
+
+  // None of our predecessor blocks contain an invalidating instruction, and we
+  // don't either!
+  return false;
+}
+
+
+/// haveEqualValueNumber - Given two load instructions, determine if they both
+/// produce the same value on every execution of the program, assuming that
+/// their source operands always give the same value.  This uses the
+/// AliasAnalysis implementation to invalidate loads when stores or function
+/// calls occur that could modify the value produced by the load.
+///
+bool LoadVN::haveEqualValueNumber(LoadInst *L1, LoadInst *L2,
+                                  AliasAnalysis &AA,
+                                  DominatorSet &DomSetInfo) const {
+  // Figure out which load dominates the other one.  If neither dominates the
+  // other we cannot eliminate them.
+  //
+  // FIXME: This could be enhanced to some cases with a shared dominator!
+  //
+  if (DomSetInfo.dominates(L2, L1)) 
+    std::swap(L1, L2);   // Make L1 dominate L2
+  else if (!DomSetInfo.dominates(L1, L2))
+    return false;  // Neither instruction dominates the other one...
+
+  BasicBlock *BB1 = L1->getParent(), *BB2 = L2->getParent();
+  Value *LoadAddress = L1->getOperand(0);
+
+  // L1 now dominates L2.  Check to see if the intervening instructions between
+  // the two loads include a store or call...
+  //
+  if (BB1 == BB2) {  // In same basic block?
+    // In this degenerate case, no checking of global basic blocks has to occur
+    // just check the instructions BETWEEN L1 & L2...
+    //
+    if (AA.canInstructionRangeModify(*L1, *L2, LoadAddress))
+      return false;   // Cannot eliminate load
+
+    // No instructions invalidate the loads, they produce the same value!
+    return true;
+  } else {
+    // Make sure that there are no store instructions between L1 and the end of
+    // it's basic block...
+    //
+    if (AA.canInstructionRangeModify(*L1, *BB1->getTerminator(), LoadAddress))
+      return false;   // Cannot eliminate load
+
+    // Make sure that there are no store instructions between the start of BB2
+    // and the second load instruction...
+    //
+    if (AA.canInstructionRangeModify(BB2->front(), *L2, LoadAddress))
+      return false;   // Cannot eliminate load
+
+    // Do a depth first traversal of the inverse CFG starting at L2's block,
+    // looking for L1's block.  The inverse CFG is made up of the predecessor
+    // nodes of a block... so all of the edges in the graph are "backward".
+    //
+    std::set<BasicBlock*> VisitedSet;
+    for (pred_iterator PI = pred_begin(BB2), PE = pred_end(BB2); PI != PE; ++PI)
+      if (CheckForInvalidatingInst(*PI, BB1, LoadAddress, AA, VisitedSet))
+        return false;
+
+    // If we passed all of these checks then we are sure that the two loads
+    // produce the same value.
+    return true;
+  }
+}