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diff --git a/lib/Transforms/IPO/PruneEH.cpp b/lib/Transforms/IPO/PruneEH.cpp
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+++ b/lib/Transforms/IPO/PruneEH.cpp
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+//===- PruneEH.cpp - Pass which deletes unused exception handlers ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a simple interprocedural pass which walks the
+// call-graph, turning invoke instructions into calls, iff the callee cannot
+// throw an exception.  It implements this as a bottom-up traversal of the
+// call-graph.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "prune-eh"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/CallGraphSCCPass.h"
+#include "llvm/Constants.h"
+#include "llvm/Function.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/Instructions.h"
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Compiler.h"
+#include <set>
+#include <algorithm>
+using namespace llvm;
+
+STATISTIC(NumRemoved, "Number of invokes removed");
+STATISTIC(NumUnreach, "Number of noreturn calls optimized");
+
+namespace {
+  struct VISIBILITY_HIDDEN PruneEH : public CallGraphSCCPass {
+    static char ID; // Pass identification, replacement for typeid
+    PruneEH() : CallGraphSCCPass((intptr_t)&ID) {}
+
+    /// DoesNotUnwind - This set contains all of the functions which we have
+    /// determined cannot unwind.
+    std::set<CallGraphNode*> DoesNotUnwind;
+
+    /// DoesNotReturn - This set contains all of the functions which we have
+    /// determined cannot return normally (but might unwind).
+    std::set<CallGraphNode*> DoesNotReturn;
+
+    // runOnSCC - Analyze the SCC, performing the transformation if possible.
+    bool runOnSCC(const std::vector<CallGraphNode *> &SCC);
+
+    bool SimplifyFunction(Function *F);
+    void DeleteBasicBlock(BasicBlock *BB);
+  };
+
+  char PruneEH::ID = 0;
+  RegisterPass<PruneEH> X("prune-eh", "Remove unused exception handling info");
+}
+
+Pass *llvm::createPruneEHPass() { return new PruneEH(); }
+
+
+bool PruneEH::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
+  CallGraph &CG = getAnalysis<CallGraph>();
+  bool MadeChange = false;
+
+  // First pass, scan all of the functions in the SCC, simplifying them
+  // according to what we know.
+  for (unsigned i = 0, e = SCC.size(); i != e; ++i)
+    if (Function *F = SCC[i]->getFunction())
+      MadeChange |= SimplifyFunction(F);
+
+  // Next, check to see if any callees might throw or if there are any external
+  // functions in this SCC: if so, we cannot prune any functions in this SCC.
+  // If this SCC includes the unwind instruction, we KNOW it throws, so
+  // obviously the SCC might throw.
+  //
+  bool SCCMightUnwind = false, SCCMightReturn = false;
+  for (unsigned i = 0, e = SCC.size();
+       (!SCCMightUnwind || !SCCMightReturn) && i != e; ++i) {
+    Function *F = SCC[i]->getFunction();
+    if (F == 0 || (F->isDeclaration() && !F->getIntrinsicID())) {
+      SCCMightUnwind = true;
+      SCCMightReturn = true;
+    } else {
+      if (F->isDeclaration())
+        SCCMightReturn = true;
+
+      // Check to see if this function performs an unwind or calls an
+      // unwinding function.
+      for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
+        if (isa<UnwindInst>(BB->getTerminator())) {  // Uses unwind!
+          SCCMightUnwind = true;
+        } else if (isa<ReturnInst>(BB->getTerminator())) {
+          SCCMightReturn = true;
+        }
+
+        // Invoke instructions don't allow unwinding to continue, so we are
+        // only interested in call instructions.
+        if (!SCCMightUnwind)
+          for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
+            if (CallInst *CI = dyn_cast<CallInst>(I)) {
+              if (Function *Callee = CI->getCalledFunction()) {
+                CallGraphNode *CalleeNode = CG[Callee];
+                // If the callee is outside our current SCC, or if it is not
+                // known to throw, then we might throw also.
+                if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()&&
+                    !DoesNotUnwind.count(CalleeNode)) {
+                  SCCMightUnwind = true;
+                  break;
+                }
+              } else {
+                // Indirect call, it might throw.
+                SCCMightUnwind = true;
+                break;
+              }
+            }
+        if (SCCMightUnwind && SCCMightReturn) break;
+      }
+    }
+  }
+
+  // If the SCC doesn't unwind or doesn't throw, note this fact.
+  if (!SCCMightUnwind)
+    for (unsigned i = 0, e = SCC.size(); i != e; ++i)
+      DoesNotUnwind.insert(SCC[i]);
+  if (!SCCMightReturn)
+    for (unsigned i = 0, e = SCC.size(); i != e; ++i)
+      DoesNotReturn.insert(SCC[i]);
+
+  for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
+    // Convert any invoke instructions to non-throwing functions in this node
+    // into call instructions with a branch.  This makes the exception blocks
+    // dead.
+    if (Function *F = SCC[i]->getFunction())
+      MadeChange |= SimplifyFunction(F);
+  }
+
+  return MadeChange;
+}
+
+
+// SimplifyFunction - Given information about callees, simplify the specified
+// function if we have invokes to non-unwinding functions or code after calls to
+// no-return functions.
+bool PruneEH::SimplifyFunction(Function *F) {
+  CallGraph &CG = getAnalysis<CallGraph>();
+  bool MadeChange = false;
+  for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
+    if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator()))
+      if (Function *F = II->getCalledFunction())
+        if (DoesNotUnwind.count(CG[F])) {
+          SmallVector<Value*, 8> Args(II->op_begin()+3, II->op_end());
+          // Insert a call instruction before the invoke.
+          CallInst *Call = new CallInst(II->getCalledValue(),
+                                        &Args[0], Args.size(), "", II);
+          Call->takeName(II);
+          Call->setCallingConv(II->getCallingConv());
+
+          // Anything that used the value produced by the invoke instruction
+          // now uses the value produced by the call instruction.
+          II->replaceAllUsesWith(Call);
+          BasicBlock *UnwindBlock = II->getUnwindDest();
+          UnwindBlock->removePredecessor(II->getParent());
+
+          // Insert a branch to the normal destination right before the
+          // invoke.
+          new BranchInst(II->getNormalDest(), II);
+
+          // Finally, delete the invoke instruction!
+          BB->getInstList().pop_back();
+
+          // If the unwind block is now dead, nuke it.
+          if (pred_begin(UnwindBlock) == pred_end(UnwindBlock))
+            DeleteBasicBlock(UnwindBlock);  // Delete the new BB.
+
+          ++NumRemoved;
+          MadeChange = true;
+        }
+
+    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; )
+      if (CallInst *CI = dyn_cast<CallInst>(I++))
+        if (Function *Callee = CI->getCalledFunction())
+          if (DoesNotReturn.count(CG[Callee]) && !isa<UnreachableInst>(I)) {
+            // This call calls a function that cannot return.  Insert an
+            // unreachable instruction after it and simplify the code.  Do this
+            // by splitting the BB, adding the unreachable, then deleting the
+            // new BB.
+            BasicBlock *New = BB->splitBasicBlock(I);
+
+            // Remove the uncond branch and add an unreachable.
+            BB->getInstList().pop_back();
+            new UnreachableInst(BB);
+
+            DeleteBasicBlock(New);  // Delete the new BB.
+            MadeChange = true;
+            ++NumUnreach;
+            break;
+          }
+
+  }
+  return MadeChange;
+}
+
+/// DeleteBasicBlock - remove the specified basic block from the program,
+/// updating the callgraph to reflect any now-obsolete edges due to calls that
+/// exist in the BB.
+void PruneEH::DeleteBasicBlock(BasicBlock *BB) {
+  assert(pred_begin(BB) == pred_end(BB) && "BB is not dead!");
+  CallGraph &CG = getAnalysis<CallGraph>();
+
+  CallGraphNode *CGN = CG[BB->getParent()];
+  for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; ) {
+    --I;
+    if (CallInst *CI = dyn_cast<CallInst>(I)) {
+      if (Function *Callee = CI->getCalledFunction())
+        CGN->removeCallEdgeTo(CG[Callee]);
+    } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
+      if (Function *Callee = II->getCalledFunction())
+        CGN->removeCallEdgeTo(CG[Callee]);
+    }
+    if (!I->use_empty())
+      I->replaceAllUsesWith(UndefValue::get(I->getType()));
+  }
+
+  // Get the list of successors of this block.
+  std::vector<BasicBlock*> Succs(succ_begin(BB), succ_end(BB));
+
+  for (unsigned i = 0, e = Succs.size(); i != e; ++i)
+    Succs[i]->removePredecessor(BB);
+
+  BB->eraseFromParent();
+}