Remove the --shrink-wrap option.

It had no tests, was unused and was "experimental at best".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193749 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 69 insertions, 1394 deletions

diff --git a/lib/CodeGen/CMakeLists.txt b/lib/CodeGen/CMakeLists.txt
index 5aa5a75069..c01875c1f8 100644
--- a/lib/CodeGen/CMakeLists.txt
+++ b/lib/CodeGen/CMakeLists.txt
@@ -89,7 +89,6 @@ add_llvm_library(LLVMCodeGen
   ScheduleDAGPrinter.cpp
   ScoreboardHazardRecognizer.cpp
   ShadowStackGC.cpp
-  ShrinkWrapping.cpp
   SjLjEHPrepare.cpp
   SlotIndexes.cpp
   SpillPlacement.cpp
diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp
index 24a03bd67d..b0e494ffcd 100644
--- a/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/lib/CodeGen/PrologEpilogInserter.cpp
@@ -14,9 +14,6 @@
 // This pass must be run after register allocation.  After this pass is
 // executed, it is illegal to construct MO_FrameIndex operands.
 //
-// This pass provides an optional shrink wrapping variant of prolog/epilog
-// insertion, enabled via --shrink-wrap. See ShrinkWrapping.cpp.
-//
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "pei"
@@ -66,6 +63,38 @@ STATISTIC(NumScavengedRegs, "Number of frame index regs scavenged");
 STATISTIC(NumBytesStackSpace,
           "Number of bytes used for stack in all functions");
 
+void PEI::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesCFG();
+  AU.addPreserved<MachineLoopInfo>();
+  AU.addPreserved<MachineDominatorTree>();
+  AU.addRequired<TargetPassConfig>();
+  MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+bool PEI::isReturnBlock(MachineBasicBlock* MBB) {
+  return (MBB && !MBB->empty() && MBB->back().isReturn());
+}
+
+/// Compute the set of return blocks
+void PEI::calculateSets(MachineFunction &Fn) {
+  // Sets used to compute spill, restore placement sets.
+  const std::vector<CalleeSavedInfo> &CSI =
+    Fn.getFrameInfo()->getCalleeSavedInfo();
+
+  // If no CSRs used, we are done.
+  if (CSI.empty())
+    return;
+
+  // Save refs to entry and return blocks.
+  EntryBlock = Fn.begin();
+  for (MachineFunction::iterator MBB = Fn.begin(), E = Fn.end();
+       MBB != E; ++MBB)
+    if (isReturnBlock(MBB))
+      ReturnBlocks.push_back(MBB);
+
+  return;
+}
+
 /// runOnMachineFunction - Insert prolog/epilog code and replace abstract
 /// frame indexes with appropriate references.
 ///
@@ -93,12 +122,8 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) {
   calculateCalleeSavedRegisters(Fn);
 
   // Determine placement of CSR spill/restore code:
-  //  - With shrink wrapping, place spills and restores to tightly
-  //    enclose regions in the Machine CFG of the function where
-  //    they are used.
-  //  - Without shink wrapping (default), place all spills in the
-  //    entry block, all restores in return blocks.
-  placeCSRSpillsAndRestores(Fn);
+  // place all spills in the entry block, all restores in return blocks.
+  calculateSets(Fn);
 
   // Add the code to save and restore the callee saved registers
   if (!F->hasFnAttribute(Attribute::Naked))
@@ -141,7 +166,7 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) {
            << ") in " << Fn.getName()  << ".\n";
 
   delete RS;
-  clearAllSets();
+  ReturnBlocks.clear();
   return true;
 }
 
@@ -283,7 +308,7 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &F) {
 }
 
 /// insertCSRSpillsAndRestores - Insert spill and restore code for
-/// callee saved registers used in the function, handling shrink wrapping.
+/// callee saved registers used in the function.
 ///
 void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) {
   // Get callee saved register information.
@@ -301,133 +326,33 @@ void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) {
   const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
   MachineBasicBlock::iterator I;
 
-  if (!ShrinkWrapThisFunction) {
-    // Spill using target interface.
-    I = EntryBlock->begin();
-    if (!TFI->spillCalleeSavedRegisters(*EntryBlock, I, CSI, TRI)) {
-      for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
-        // Add the callee-saved register as live-in.
-        // It's killed at the spill.
-        EntryBlock->addLiveIn(CSI[i].getReg());
-
-        // Insert the spill to the stack frame.
-        unsigned Reg = CSI[i].getReg();
-        const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
-        TII.storeRegToStackSlot(*EntryBlock, I, Reg, true,
-                                CSI[i].getFrameIdx(), RC, TRI);
-      }
-    }
-
-    // Restore using target interface.
-    for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri) {
-      MachineBasicBlock* MBB = ReturnBlocks[ri];
-      I = MBB->end(); --I;
-
-      // Skip over all terminator instructions, which are part of the return
-      // sequence.
-      MachineBasicBlock::iterator I2 = I;
-      while (I2 != MBB->begin() && (--I2)->isTerminator())
-        I = I2;
-
-      bool AtStart = I == MBB->begin();
-      MachineBasicBlock::iterator BeforeI = I;
-      if (!AtStart)
-        --BeforeI;
-
-      // Restore all registers immediately before the return and any
-      // terminators that precede it.
-      if (!TFI->restoreCalleeSavedRegisters(*MBB, I, CSI, TRI)) {
-        for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
-          unsigned Reg = CSI[i].getReg();
-          const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
-          TII.loadRegFromStackSlot(*MBB, I, Reg,
-                                   CSI[i].getFrameIdx(),
-                                   RC, TRI);
-          assert(I != MBB->begin() &&
-                 "loadRegFromStackSlot didn't insert any code!");
-          // Insert in reverse order.  loadRegFromStackSlot can insert
-          // multiple instructions.
-          if (AtStart)
-            I = MBB->begin();
-          else {
-            I = BeforeI;
-            ++I;
-          }
-        }
-      }
-    }
-    return;
-  }
-
-  // Insert spills.
-  std::vector<CalleeSavedInfo> blockCSI;
-  for (CSRegBlockMap::iterator BI = CSRSave.begin(),
-         BE = CSRSave.end(); BI != BE; ++BI) {
-    MachineBasicBlock* MBB = BI->first;
-    CSRegSet save = BI->second;
-
-    if (save.empty())
-      continue;
-
-    blockCSI.clear();
-    for (CSRegSet::iterator RI = save.begin(),
-           RE = save.end(); RI != RE; ++RI) {
-      blockCSI.push_back(CSI[*RI]);
-    }
-    assert(blockCSI.size() > 0 &&
-           "Could not collect callee saved register info");
-
-    I = MBB->begin();
-
-    // When shrink wrapping, use stack slot stores/loads.
-    for (unsigned i = 0, e = blockCSI.size(); i != e; ++i) {
+  // Spill using target interface.
+  I = EntryBlock->begin();
+  if (!TFI->spillCalleeSavedRegisters(*EntryBlock, I, CSI, TRI)) {
+    for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
       // Add the callee-saved register as live-in.
       // It's killed at the spill.
-      MBB->addLiveIn(blockCSI[i].getReg());
+      EntryBlock->addLiveIn(CSI[i].getReg());
 
       // Insert the spill to the stack frame.
-      unsigned Reg = blockCSI[i].getReg();
+      unsigned Reg = CSI[i].getReg();
       const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
-      TII.storeRegToStackSlot(*MBB, I, Reg,
-                              true,
-                              blockCSI[i].getFrameIdx(),
+      TII.storeRegToStackSlot(*EntryBlock, I, Reg, true, CSI[i].getFrameIdx(),
                               RC, TRI);
     }
   }
 
-  for (CSRegBlockMap::iterator BI = CSRRestore.begin(),
-         BE = CSRRestore.end(); BI != BE; ++BI) {
-    MachineBasicBlock* MBB = BI->first;
-    CSRegSet restore = BI->second;
-
-    if (restore.empty())
-      continue;
+  // Restore using target interface.
+  for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri) {
+    MachineBasicBlock *MBB = ReturnBlocks[ri];
+    I = MBB->end();
+    --I;
 
-    blockCSI.clear();
-    for (CSRegSet::iterator RI = restore.begin(),
-           RE = restore.end(); RI != RE; ++RI) {
-      blockCSI.push_back(CSI[*RI]);
-    }
-    assert(blockCSI.size() > 0 &&
-           "Could not find callee saved register info");
-
-    // If MBB is empty and needs restores, insert at the _beginning_.
-    if (MBB->empty()) {
-      I = MBB->begin();
-    } else {
-      I = MBB->end();
-      --I;
-
-      // Skip over all terminator instructions, which are part of the
-      // return sequence.
-      if (! I->isTerminator()) {
-        ++I;
-      } else {
-        MachineBasicBlock::iterator I2 = I;
-        while (I2 != MBB->begin() && (--I2)->isTerminator())
-          I = I2;
-      }
-    }
+    // Skip over all terminator instructions, which are part of the return
+    // sequence.
+    MachineBasicBlock::iterator I2 = I;
+    while (I2 != MBB->begin() && (--I2)->isTerminator())
+      I = I2;
 
     bool AtStart = I == MBB->begin();
     MachineBasicBlock::iterator BeforeI = I;
@@ -436,21 +361,21 @@ void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) {
 
     // Restore all registers immediately before the return and any
     // terminators that precede it.
-    for (unsigned i = 0, e = blockCSI.size(); i != e; ++i) {
-      unsigned Reg = blockCSI[i].getReg();
-      const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
-      TII.loadRegFromStackSlot(*MBB, I, Reg,
-                               blockCSI[i].getFrameIdx(),
-                               RC, TRI);
-      assert(I != MBB->begin() &&
-             "loadRegFromStackSlot didn't insert any code!");
-      // Insert in reverse order.  loadRegFromStackSlot can insert
-      // multiple instructions.
-      if (AtStart)
-        I = MBB->begin();
-      else {
-        I = BeforeI;
-        ++I;
+    if (!TFI->restoreCalleeSavedRegisters(*MBB, I, CSI, TRI)) {
+      for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+        unsigned Reg = CSI[i].getReg();
+        const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
+        TII.loadRegFromStackSlot(*MBB, I, Reg, CSI[i].getFrameIdx(), RC, TRI);
+        assert(I != MBB->begin() &&
+               "loadRegFromStackSlot didn't insert any code!");
+        // Insert in reverse order.  loadRegFromStackSlot can insert
+        // multiple instructions.
+        if (AtStart)
+          I = MBB->begin();
+        else {
+          I = BeforeI;
+          ++I;
+        }
       }
     }
   }
diff --git a/lib/CodeGen/PrologEpilogInserter.h b/lib/CodeGen/PrologEpilogInserter.h
index 50f4daf733..77cfa2b09e 100644
--- a/lib/CodeGen/PrologEpilogInserter.h
+++ b/lib/CodeGen/PrologEpilogInserter.h
@@ -14,9 +14,6 @@
 // This pass must be run after register allocation.  After this pass is
 // executed, it is illegal to construct MO_FrameIndex operands.
 //
-// This pass also implements a shrink wrapping variant of prolog/epilog
-// insertion.
-//
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CODEGEN_PEI_H
@@ -54,74 +51,16 @@ namespace llvm {
     // stack frame indexes.
     unsigned MinCSFrameIndex, MaxCSFrameIndex;
 
-    // Analysis info for spill/restore placement.
-    // "CSR": "callee saved register".
-
-    // CSRegSet contains indices into the Callee Saved Register Info
-    // vector built by calculateCalleeSavedRegisters() and accessed
-    // via MF.getFrameInfo()->getCalleeSavedInfo().
-    typedef SparseBitVector<> CSRegSet;
-
-    // CSRegBlockMap maps MachineBasicBlocks to sets of callee
-    // saved register indices.
-    typedef DenseMap<MachineBasicBlock*, CSRegSet> CSRegBlockMap;
-
-    // Set and maps for computing CSR spill/restore placement:
-    //  used in function (UsedCSRegs)
-    //  used in a basic block (CSRUsed)
-    //  anticipatable in a basic block (Antic{In,Out})
-    //  available in a basic block (Avail{In,Out})
-    //  to be spilled at the entry to a basic block (CSRSave)
-    //  to be restored at the end of a basic block (CSRRestore)
-    CSRegSet UsedCSRegs;
-    CSRegBlockMap CSRUsed;
-    CSRegBlockMap AnticIn, AnticOut;
-    CSRegBlockMap AvailIn, AvailOut;
-    CSRegBlockMap CSRSave;
-    CSRegBlockMap CSRRestore;
-
     // Entry and return blocks of the current function.
     MachineBasicBlock* EntryBlock;
     SmallVector<MachineBasicBlock*, 4> ReturnBlocks;
 
-    // Map of MBBs to top level MachineLoops.
-    DenseMap<MachineBasicBlock*, MachineLoop*> TLLoops;
-
-    // Flag to control shrink wrapping per-function:
-    // may choose to skip shrink wrapping for certain
-    // functions.
-    bool ShrinkWrapThisFunction;
-
     // Flag to control whether to use the register scavenger to resolve
     // frame index materialization registers. Set according to
     // TRI->requiresFrameIndexScavenging() for the curren function.
     bool FrameIndexVirtualScavenging;
 
-#ifndef NDEBUG
-    // Machine function handle.
-    MachineFunction* MF;
-
-    // Flag indicating that the current function
-    // has at least one "short" path in the machine
-    // CFG from the entry block to an exit block.
-    bool HasFastExitPath;
-#endif
-
-    bool calculateSets(MachineFunction &Fn);
-    bool calcAnticInOut(MachineBasicBlock* MBB);
-    bool calcAvailInOut(MachineBasicBlock* MBB);
-    void calculateAnticAvail(MachineFunction &Fn);
-    bool addUsesForMEMERegion(MachineBasicBlock* MBB,
-                              SmallVectorImpl<MachineBasicBlock *> &blks);
-    bool addUsesForTopLevelLoops(SmallVectorImpl<MachineBasicBlock *> &blks);
-    bool calcSpillPlacements(MachineBasicBlock* MBB,
-                             SmallVectorImpl<MachineBasicBlock *> &blks,
-                             CSRegBlockMap &prevSpills);
-    bool calcRestorePlacements(MachineBasicBlock* MBB,
-                               SmallVectorImpl<MachineBasicBlock *> &blks,
-                               CSRegBlockMap &prevRestores);
-    void placeSpillsAndRestores(MachineFunction &Fn);
-    void placeCSRSpillsAndRestores(MachineFunction &Fn);
+    void calculateSets(MachineFunction &Fn);
     void calculateCallsInformation(MachineFunction &Fn);
     void calculateCalleeSavedRegisters(MachineFunction &Fn);
     void insertCSRSpillsAndRestores(MachineFunction &Fn);
@@ -132,44 +71,8 @@ namespace llvm {
     void scavengeFrameVirtualRegs(MachineFunction &Fn);
     void insertPrologEpilogCode(MachineFunction &Fn);
 
-    // Initialize DFA sets, called before iterations.
-    void clearAnticAvailSets();
-    // Clear all sets constructed by shrink wrapping.
-    void clearAllSets();
-
-    // Initialize all shrink wrapping data.
-    void initShrinkWrappingInfo();
-
-    // Convienences for dealing with machine loops.
-    MachineBasicBlock* getTopLevelLoopPreheader(MachineLoop* LP);
-    MachineLoop* getTopLevelLoopParent(MachineLoop *LP);
-
-    // Propgate CSRs used in MBB to all MBBs of loop LP.
-    void propagateUsesAroundLoop(MachineBasicBlock* MBB, MachineLoop* LP);
-
     // Convenience for recognizing return blocks.
     bool isReturnBlock(MachineBasicBlock* MBB);
-
-#ifndef NDEBUG
-    // Debugging methods.
-
-    // Mark this function as having fast exit paths.
-    void findFastExitPath();
-
-    // Verify placement of spills/restores.
-    void verifySpillRestorePlacement();
-
-    std::string getBasicBlockName(const MachineBasicBlock* MBB);
-    std::string stringifyCSRegSet(const CSRegSet& s);
-    void dumpSet(const CSRegSet& s);
-    void dumpUsed(MachineBasicBlock* MBB);
-    void dumpAllUsed();
-    void dumpSets(MachineBasicBlock* MBB);
-    void dumpSets1(MachineBasicBlock* MBB);
-    void dumpAllSets();
-    void dumpSRSets();
-#endif
-
   };
 } // End llvm namespace
 #endif
diff --git a/lib/CodeGen/ShrinkWrapping.cpp b/lib/CodeGen/ShrinkWrapping.cpp
deleted file mode 100644
index 2b01fdd8d0..0000000000
--- a/lib/CodeGen/ShrinkWrapping.cpp
+++ /dev/null
@@ -1,1152 +0,0 @@
-//===-- ShrinkWrapping.cpp - Reduce spills/restores of callee-saved regs --===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements a shrink wrapping variant of prolog/epilog insertion:
-// - Spills and restores of callee-saved registers (CSRs) are placed in the
-//   machine CFG to tightly surround their uses so that execution paths that
-//   do not use CSRs do not pay the spill/restore penalty.
-//
-// - Avoiding placment of spills/restores in loops: if a CSR is used inside a
-//   loop the spills are placed in the loop preheader, and restores are
-//   placed in the loop exit nodes (the successors of loop _exiting_ nodes).
-//
-// - Covering paths without CSR uses:
-//   If a region in a CFG uses CSRs and has multiple entry and/or exit points,
-//   the use info for the CSRs inside the region is propagated outward in the
-//   CFG to ensure validity of the spill/restore placements. This decreases
-//   the effectiveness of shrink wrapping but does not require edge splitting
-//   in the machine CFG.
-//
-// This shrink wrapping implementation uses an iterative analysis to determine
-// which basic blocks require spills and restores for CSRs.
-//
-// This pass uses MachineDominators and MachineLoopInfo. Loop information
-// is used to prevent placement of callee-saved register spills/restores
-// in the bodies of loops.
-//
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "shrink-wrap"
-
-#include "PrologEpilogInserter.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/PostOrderIterator.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SparseBitVector.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/CodeGen/MachineDominators.h"
-#include "llvm/CodeGen/MachineFrameInfo.h"
-#include "llvm/CodeGen/MachineInstr.h"
-#include "llvm/CodeGen/MachineLoopInfo.h"
-#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Compiler.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetRegisterInfo.h"
-#include <sstream>
-
-using namespace llvm;
-
-STATISTIC(numSRReduced, "Number of CSR spills+restores reduced.");
-
-// Shrink Wrapping:
-static cl::opt<bool>
-ShrinkWrapping("shrink-wrap",
-               cl::desc("Shrink wrap callee-saved register spills/restores"));
-
-// Shrink wrap only the specified function, a debugging aid.
-static cl::opt<std::string>
-ShrinkWrapFunc("shrink-wrap-func", cl::Hidden,
-               cl::desc("Shrink wrap the specified function"),
-               cl::value_desc("funcname"),
-               cl::init(""));
-
-// Debugging level for shrink wrapping.
-enum ShrinkWrapDebugLevel {
-  Disabled, BasicInfo, Iterations, Details
-};
-
-static cl::opt<enum ShrinkWrapDebugLevel>
-ShrinkWrapDebugging("shrink-wrap-dbg", cl::Hidden,
-  cl::desc("Print shrink wrapping debugging information"),
-  cl::values(
-    clEnumVal(Disabled  , "disable debug output"),
-    clEnumVal(BasicInfo , "print basic DF sets"),
-    clEnumVal(Iterations, "print SR sets for each iteration"),
-    clEnumVal(Details   , "print all DF sets"),
-    clEnumValEnd));
-
-
-void PEI::getAnalysisUsage(AnalysisUsage &AU) const {
-  AU.setPreservesCFG();
-  if (ShrinkWrapping || ShrinkWrapFunc != "") {
-    AU.addRequired<MachineLoopInfo>();
-    AU.addRequired<MachineDominatorTree>();
-  }
-  AU.addPreserved<MachineLoopInfo>();
-  AU.addPreserved<MachineDominatorTree>();
-  AU.addRequired<TargetPassConfig>();
-  MachineFunctionPass::getAnalysisUsage(AU);
-}
-
-//===----------------------------------------------------------------------===//
-//  ShrinkWrapping implementation
-//===----------------------------------------------------------------------===//
-
-// Convienences for dealing with machine loops.
-MachineBasicBlock* PEI::getTopLevelLoopPreheader(MachineLoop* LP) {
-  assert(LP && "Machine loop is NULL.");
-  MachineBasicBlock* PHDR = LP->getLoopPreheader();
-  MachineLoop* PLP = LP->getParentLoop();
-  while (PLP) {
-    PHDR = PLP->getLoopPreheader();
-    PLP = PLP->getParentLoop();
-  }
-  return PHDR;
-}
-
-MachineLoop* PEI::getTopLevelLoopParent(MachineLoop *LP) {
-  if (LP == 0)
-    return 0;
-  MachineLoop* PLP = LP->getParentLoop();
-  while (PLP) {
-    LP = PLP;
-    PLP = PLP->getParentLoop();
-  }
-  return LP;
-}
-
-bool PEI::isReturnBlock(MachineBasicBlock* MBB) {
-  return (MBB && !MBB->empty() && MBB->back().isReturn());
-}
-
-// Initialize shrink wrapping DFA sets, called before iterations.
-void PEI::clearAnticAvailSets() {
-  AnticIn.clear();
-  AnticOut.clear();
-  AvailIn.clear();
-  AvailOut.clear();
-}
-
-// Clear all sets constructed by shrink wrapping.
-void PEI::clearAllSets() {
-  ReturnBlocks.clear();
-  clearAnticAvailSets();
-  UsedCSRegs.clear();
-  CSRUsed.clear();
-  TLLoops.clear();
-  CSRSave.clear();
-  CSRRestore.clear();
-}
-
-// Initialize all shrink wrapping data.
-void PEI::initShrinkWrappingInfo() {
-  clearAllSets();
-  EntryBlock = 0;
-#ifndef NDEBUG
-  HasFastExitPath = false;
-#endif
-  ShrinkWrapThisFunction = ShrinkWrapping;
-  // DEBUG: enable or disable shrink wrapping for the current function
-  // via --shrink-wrap-func=<funcname>.
-#ifndef NDEBUG
-  if (ShrinkWrapFunc != "") {
-    std::string MFName = MF->getName().str();
-    ShrinkWrapThisFunction = (MFName == ShrinkWrapFunc);
-  }
-#endif
-}
-
-
-/// placeCSRSpillsAndRestores - determine which MBBs of the function
-/// need save, restore code for callee-saved registers by doing a DF analysis
-/// similar to the one used in code motion (GVNPRE). This produces maps of MBBs
-/// to sets of registers (CSRs) for saves and restores. MachineLoopInfo
-/// is used to ensure that CSR save/restore code is not placed inside loops.
-/// This function computes the maps of MBBs -> CSRs to spill and restore
-/// in CSRSave, CSRRestore.
-///
-/// If shrink wrapping is not being performed, place all spills in
-/// the entry block, all restores in return blocks. In this case,
-/// CSRSave has a single mapping, CSRRestore has mappings for each
-/// return block.
-///
-void PEI::placeCSRSpillsAndRestores(MachineFunction &Fn) {
-
-  DEBUG(MF = &Fn);
-
-  initShrinkWrappingInfo();
-
-  DEBUG(if (ShrinkWrapThisFunction) {
-      dbgs() << "Place CSR spills/restores for "
-             << MF->getName() << "\n";
-    });
-
-  if (calculateSets(Fn))
-    placeSpillsAndRestores(Fn);
-}
-
-/// calcAnticInOut - calculate the anticipated in/out reg sets
-/// for the given MBB by looking forward in the MCFG at MBB's
-/// successors.
-///
-bool PEI::calcAnticInOut(MachineBasicBlock* MBB) {
-  bool changed = false;
-
-  // AnticOut[MBB] = INTERSECT(AnticIn[S] for S in SUCCESSORS(MBB))
-  SmallVector<MachineBasicBlock*, 4> successors;
-  for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
-         SE = MBB->succ_end(); SI != SE; ++SI) {
-    MachineBasicBlock* SUCC = *SI;
-    if (SUCC != MBB)
-      successors.push_back(SUCC);
-  }
-
-  unsigned i = 0, e = successors.size();
-  if (i != e) {
-    CSRegSet prevAnticOut = AnticOut[MBB];
-    MachineBasicBlock* SUCC = successors[i];
-
-    AnticOut[MBB] = AnticIn[SUCC];
-    for (++i; i != e; ++i) {
-      SUCC = successors[i];
-      AnticOut[MBB] &= AnticIn[SUCC];
-    }
-    if (prevAnticOut != AnticOut[MBB])
-      changed = true;
-  }
-
-  // AnticIn[MBB] = UNION(CSRUsed[MBB], AnticOut[MBB]);
-  CSRegSet prevAnticIn = AnticIn[MBB];
-  AnticIn[MBB] = CSRUsed[MBB] | AnticOut[MBB];
-  if (prevAnticIn != AnticIn[MBB])
-    changed = true;
-  return changed;
-}
-
-/// calcAvailInOut - calculate the available in/out reg sets
-/// for the given MBB by looking backward in the MCFG at MBB's
-/// predecessors.
-///
-bool PEI::calcAvailInOut(MachineBasicBlock* MBB) {
-  bool changed = false;
-
-  // AvailIn[MBB] = INTERSECT(AvailOut[P] for P in PREDECESSORS(MBB))
-  SmallVector<MachineBasicBlock*, 4> predecessors;
-  for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
-         PE = MBB->pred_end(); PI != PE; ++PI) {
-    MachineBasicBlock* PRED = *PI;
-    if (PRED != MBB)
-      predecessors.push_back(PRED);
-  }
-
-  unsigned i = 0, e = predecessors.size();
-  if (i != e) {
-    CSRegSet prevAvailIn = AvailIn[MBB];
-    MachineBasicBlock* PRED = predecessors[i];
-
-    AvailIn[MBB] = AvailOut[PRED];
-    for (++i; i != e; ++i) {
-      PRED = predecessors[i];
-      AvailIn[MBB] &= AvailOut[PRED];
-    }
-    if (prevAvailIn != AvailIn[MBB])
-      changed = true;
-  }
-
-  // AvailOut[MBB] = UNION(CSRUsed[MBB], AvailIn[MBB]);
-  CSRegSet prevAvailOut = AvailOut[MBB];
-  AvailOut[MBB] = CSRUsed[MBB] | AvailIn[MBB];
-  if (prevAvailOut != AvailOut[MBB])
-    changed = true;
-  return changed;
-}
-
-/// calculateAnticAvail - build the sets anticipated and available
-/// registers in the MCFG of the current function iteratively,
-/// doing a combined forward and backward analysis.
-///
-void PEI::calculateAnticAvail(MachineFunction &Fn) {
-  // Initialize data flow sets.
-  clearAnticAvailSets();
-
-  // Calculate Antic{In,Out} and Avail{In,Out} iteratively on the MCFG.
-  bool changed = true;
-  unsigned iterations = 0;
-  while (changed) {
-    changed = false;
-    ++iterations;
-    for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
-         MBBI != MBBE; ++MBBI) {
-      MachineBasicBlock* MBB = MBBI;
-
-      // Calculate anticipated in, out regs at MBB from
-      // anticipated at successors of MBB.
-      changed |= calcAnticInOut(MBB);
-
-      // Calculate available in, out regs at MBB from
-      // available at predecessors of MBB.
-      changed |= calcAvailInOut(MBB);
-    }
-  }
-
-  DEBUG({
-      if (ShrinkWrapDebugging >= Details) {
-        dbgs()
-          << "-----------------------------------------------------------\n"
-          << " Antic/Avail Sets:\n"
-          << "-----------------------------------------------------------\n"
-          << "iterations = " << iterations << "\n"
-          << "-----------------------------------------------------------\n"
-          << "MBB | USED | ANTIC_IN | ANTIC_OUT | AVAIL_IN | AVAIL_OUT\n"
-          << "-----------------------------------------------------------\n";
-
-        for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
-             MBBI != MBBE; ++MBBI) {
-          MachineBasicBlock* MBB = MBBI;
-          dumpSets(MBB);
-        }
-
-        dbgs()
-          << "-----------------------------------------------------------\n";
-      }
-    });
-}
-
-/// propagateUsesAroundLoop - copy used register info from MBB to all blocks
-/// of the loop given by LP and its parent loops. This prevents spills/restores
-/// from being placed in the bodies of loops.
-///
-void PEI::propagateUsesAroundLoop(MachineBasicBlock* MBB, MachineLoop* LP) {
-  if (! MBB || !LP)
-    return;
-
-  std::vector<MachineBasicBlock*> loopBlocks = LP->getBlocks();
-  for (unsigned i = 0, e = loopBlocks.size(); i != e; ++i) {
-    MachineBasicBlock* LBB = loopBlocks[i];
-    if (LBB == MBB)
-      continue;
-    if (CSRUsed[LBB].contains(CSRUsed[MBB]))
-      continue;
-    CSRUsed[LBB] |= CSRUsed[MBB];
-  }
-}
-
-/// calculateSets - collect the CSRs used in this function, compute
-/// the DF sets that describe the initial minimal regions in the
-/// Machine CFG around which CSR spills and restores must be placed.
-///
-/// Additionally, this function decides if shrink wrapping should
-/// be disabled for the current function, checking the following:
-///  1. the current function has more than 500 MBBs: heuristic limit
-///     on function size to reduce compile time impact of the current
-///     iterative algorithm.
-///  2. all CSRs are used in the entry block.
-///  3. all CSRs are used in all immediate successors of the entry block.
-///  4. all CSRs are used in a subset of blocks, each of which dominates
-///     all return blocks. These blocks, taken as a subgraph of the MCFG,
-///     are equivalent to the entry block since all execution paths pass
-///     through them.
-///
-bool PEI::calculateSets(MachineFunction &Fn) {
-  // Sets used to compute spill, restore placement sets.
-  const std::vector<CalleeSavedInfo> &CSI =
-    Fn.getFrameInfo()->getCalleeSavedInfo();
-
-  // If no CSRs used, we are done.
-  if (CSI.empty()) {
-    DEBUG(if (ShrinkWrapThisFunction)
-            dbgs() << "DISABLED: " << Fn.getName()
-                   << ": uses no callee-saved registers\n");
-    return false;
-  }
-
-  // Save refs to entry and return blocks.
-  EntryBlock = Fn.begin();
-  for (MachineFunction::iterator MBB = Fn.begin(), E = Fn.end();
-       MBB != E; ++MBB)
-    if (isReturnBlock(MBB))
-      ReturnBlocks.push_back(MBB);
-
-  // Determine if this function has fast exit paths.
-  DEBUG(if (ShrinkWrapThisFunction)
-          findFastExitPath());
-
-  // Limit shrink wrapping via the current iterative bit vector
-  // implementation to functions with <= 500 MBBs.
-  if (Fn.size() > 500) {
-    DEBUG(if (ShrinkWrapThisFunction)
-            dbgs() << "DISABLED: " << Fn.getName()
-                   << ": too large (" << Fn.size() << " MBBs)\n");
-    ShrinkWrapThisFunction = false;
-  }
-
-  // Return now if not shrink wrapping.
-  if (! ShrinkWrapThisFunction)
-    return false;
-
-  // Collect set of used CSRs.
-  for (unsigned inx = 0, e = CSI.size(); inx != e; ++inx) {
-    UsedCSRegs.set(inx);
-  }
-
-  // Walk instructions in all MBBs, create CSRUsed[] sets, choose
-  // whether or not to shrink wrap this function.
-  MachineLoopInfo &LI = getAnalysis<MachineLoopInfo>();
-  MachineDominatorTree &DT = getAnalysis<MachineDominatorTree>();
-  const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
-
-  bool allCSRUsesInEntryBlock = true;
-  for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
-       MBBI != MBBE; ++MBBI) {
-    MachineBasicBlock* MBB = MBBI;
-    for (MachineBasicBlock::iterator I = MBB->begin(); I != MBB->end(); ++I) {
-      for (unsigned inx = 0, e = CSI.size(); inx != e; ++inx) {
-        unsigned Reg = CSI[inx].getReg();
-        // If instruction I reads or modifies Reg, add it to UsedCSRegs,
-        // CSRUsed map for the current block.
-        for (unsigned opInx = 0, opEnd = I->getNumOperands();
-             opInx != opEnd; ++opInx) {
-          const MachineOperand &MO = I->getOperand(opInx);
-          if (! (MO.isReg() && (MO.isUse() || MO.isDef())))
-            continue;
-          unsigned MOReg = MO.getReg();
-          if (!MOReg)
-            continue;
-          if (MOReg == Reg ||
-              (TargetRegisterInfo::isPhysicalRegister(MOReg) &&
-               TargetRegisterInfo::isPhysicalRegister(Reg) &&
-               TRI->isSubRegister(Reg, MOReg))) {
-            // CSR Reg is defined/used in block MBB.
-            CSRUsed[MBB].set(inx);
-            // Check for uses in EntryBlock.
-            if (MBB != EntryBlock)
-              allCSRUsesInEntryBlock = false;
-          }
-        }
-      }
-    }
-
-    if (CSRUsed[MBB].empty())
-      continue;
-
-    // Propagate CSRUsed[MBB] in loops
-    if (MachineLoop* LP = LI.getLoopFor(MBB)) {
-      // Add top level loop to work list.
-      MachineBasicBlock* HDR = getTopLevelLoopPreheader(LP);
-      MachineLoop* PLP = getTopLevelLoopParent(LP);
-
-      if (! HDR) {
-        HDR = PLP->getHeader();
-        assert(HDR->pred_size() > 0 && "Loop header has no predecessors?");
-        MachineBasicBlock::pred_iterator PI = HDR->pred_begin();
-        HDR = *PI;
-      }
-      TLLoops[HDR] = PLP;
-
-      // Push uses from inside loop to its parent loops,
-      // or to all other MBBs in its loop.
-      if (LP->getLoopDepth() > 1) {
-        for (MachineLoop* PLP = LP->getParentLoop(); PLP;
-             PLP = PLP->getParentLoop()) {
-          propagateUsesAroundLoop(MBB, PLP);
-        }
-      } else {
-        propagateUsesAroundLoop(MBB, LP);
-      }
-    }
-  }
-
-  if (allCSRUsesInEntryBlock) {
-    DEBUG(dbgs() << "DISABLED: " << Fn.getName()
-                 << ": all CSRs used in EntryBlock\n");
-    ShrinkWrapThisFunction = false;
-  } else {
-    bool allCSRsUsedInEntryFanout = true;
-    for (MachineBasicBlock::succ_iterator SI = EntryBlock->succ_begin(),
-           SE = EntryBlock->succ_end(); SI != SE; ++SI) {
-      MachineBasicBlock* SUCC = *SI;
-      if (CSRUsed[SUCC] != UsedCSRegs)
-        allCSRsUsedInEntryFanout = false;
-    }
-    if (allCSRsUsedInEntryFanout) {
-      DEBUG(dbgs() << "DISABLED: " << Fn.getName()
-                   << ": all CSRs used in imm successors of EntryBlock\n");
-      ShrinkWrapThisFunction = false;
-    }
-  }
-
-  if (ShrinkWrapThisFunction) {
-    // Check if MBB uses CSRs and dominates all exit nodes.
-    // Such nodes are equiv. to the entry node w.r.t.
-    // CSR uses: every path through the function must
-    // pass through this node. If each CSR is used at least
-    // once by these nodes, shrink wrapping is disabled.
-    CSRegSet CSRUsedInChokePoints;
-    for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
-         MBBI != MBBE; ++MBBI) {
-      MachineBasicBlock* MBB = MBBI;
-      if (MBB == EntryBlock || CSRUsed[MBB].empty() || MBB->succ_size() < 1)
-        continue;
-      bool dominatesExitNodes = true;
-      for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri)
-        if (! DT.dominates(MBB, ReturnBlocks[ri])) {
-          dominatesExitNodes = false;
-          break;
-        }
-      if (dominatesExitNodes) {
-        CSRUsedInChokePoints |= CSRUsed[MBB];
-        if (CSRUsedInChokePoints == UsedCSRegs) {
-          DEBUG(dbgs() << "DISABLED: " << Fn.getName()
-                       << ": all CSRs used in choke point(s) at "
-                       << getBasicBlockName(MBB) << "\n");
-          ShrinkWrapThisFunction = false;
-          break;
-        }
-      }
-    }
-  }
-
-  // Return now if we have decided not to apply shrink wrapping
-  // to the current function.
-  if (! ShrinkWrapThisFunction)
-    return false;
-
-  DEBUG({
-      dbgs() << "ENABLED: " << Fn.getName();
-      if (HasFastExitPath)
-        dbgs() << " (fast exit path)";
-      dbgs() << "\n";
-      if (ShrinkWrapDebugging >= BasicInfo) {
-        dbgs() << "------------------------------"
-             << "-----------------------------\n";
-        dbgs() << "UsedCSRegs = " << stringifyCSRegSet(UsedCSRegs) << "\n";
-        if (ShrinkWrapDebugging >= Details) {
-          dbgs() << "------------------------------"
-               << "-----------------------------\n";
-          dumpAllUsed();
-        }
-      }
-    });
-
-  // Build initial DF sets to determine minimal regions in the
-  // Machine CFG around which CSRs must be spilled and restored.
-  calculateAnticAvail(Fn);
-
-  return true;
-}
-
-/// addUsesForMEMERegion - add uses of CSRs spilled or restored in
-/// multi-entry, multi-exit (MEME) regions so spill and restore
-/// placement will not break code that enters or leaves a
-/// shrink-wrapped region by inducing spills with no matching
-/// restores or restores with no matching spills. A MEME region
-/// is a subgraph of the MCFG with multiple entry edges, multiple
-/// exit edges, or both. This code propagates use information
-/// through the MCFG until all paths requiring spills and restores
-/// _outside_ the computed minimal placement regions have been covered.
-///
-bool PEI::addUsesForMEMERegion(MachineBasicBlock* MBB,
-                               SmallVectorImpl<MachineBasicBlock *> &blks) {
-  if (MBB->succ_size() < 2 && MBB->pred_size() < 2) {
-    bool processThisBlock = false;
-    for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
-           SE = MBB->succ_end(); SI != SE; ++SI) {
-      MachineBasicBlock* SUCC = *SI;
-      if (SUCC->pred_size() > 1) {
-        processThisBlock = true;
-        break;
-      }
-    }
-    if (!CSRRestore[MBB].empty() && MBB->succ_size() > 0) {
-      for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
-             PE = MBB->pred_end(); PI != PE; ++PI) {
-        MachineBasicBlock* PRED = *PI;
-        if (PRED->succ_size() > 1) {
-          processThisBlock = true;
-          break;
-        }
-      }
-    }
-    if (! processThisBlock)
-      return false;
-  }
-
-  CSRegSet prop;
-  if (!CSRSave[MBB].empty())
-    prop = CSRSave[MBB];
-  else if (!CSRRestore[MBB].empty())
-    prop = CSRRestore[MBB];
-  else
-    prop = CSRUsed[MBB];
-  if (prop.empty())
-    return false;
-
-  // Propagate selected bits to successors, predecessors of MBB.
-  bool addedUses = false;
-  for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
-         SE = MBB->succ_end(); SI != SE; ++SI) {
-    MachineBasicBlock* SUCC = *SI;
-    // Self-loop
-    if (SUCC == MBB)
-      continue;
-    if (! CSRUsed[SUCC].contains(prop)) {
-      CSRUsed[SUCC] |= prop;
-      addedUses = true;
-      blks.push_back(SUCC);
-      DEBUG(if (ShrinkWrapDebugging >= Iterations)
-              dbgs() << getBasicBlockName(MBB)
-                   << "(" << stringifyCSRegSet(prop) << ")->"
-                   << "successor " << getBasicBlockName(SUCC) << "\n");
-    }
-  }
-  for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
-         PE = MBB->pred_end(); PI != PE; ++PI) {
-    MachineBasicBlock* PRED = *PI;
-    // Self-loop
-    if (PRED == MBB)
-      continue;
-    if (! CSRUsed[PRED].contains(prop)) {
-      CSRUsed[PRED] |= prop;
-      addedUses = true;
-      blks.push_back(PRED);
-      DEBUG(if (ShrinkWrapDebugging >= Iterations)
-              dbgs() << getBasicBlockName(MBB)
-                   << "(" << stringifyCSRegSet(prop) << ")->"
-                   << "predecessor " << getBasicBlockName(PRED) << "\n");
-    }
-  }
-  return addedUses;
-}
-
-/// addUsesForTopLevelLoops - add uses for CSRs used inside top
-/// level loops to the exit blocks of those loops.
-///
-bool PEI::addUsesForTopLevelLoops(SmallVectorImpl<MachineBasicBlock *> &blks) {
-  bool addedUses = false;
-
-  // Place restores for top level loops where needed.
-  for (DenseMap<MachineBasicBlock*, MachineLoop*>::iterator
-         I = TLLoops.begin(), E = TLLoops.end(); I != E; ++I) {
-    MachineBasicBlock* MBB = I->first;
-    MachineLoop* LP = I->second;
-    MachineBasicBlock* HDR = LP->getHeader();
-    SmallVector<MachineBasicBlock*, 4> exitBlocks;
-    CSRegSet loopSpills;
-
-    loopSpills = CSRSave[MBB];
-    if (CSRSave[MBB].empty()) {
-      loopSpills = CSRUsed[HDR];
-      assert(!loopSpills.empty() && "No CSRs used in loop?");
-    } else if (CSRRestore[MBB].contains(CSRSave[MBB]))
-      continue;
-
-    LP->getExitBlocks(exitBlocks);
-    assert(exitBlocks.size() > 0 && "Loop has no top level exit blocks?");
-    for (unsigned i = 0, e = exitBlocks.size(); i != e; ++i) {
-      MachineBasicBlock* EXB = exitBlocks[i];
-      if (! CSRUsed[EXB].contains(loopSpills)) {
-        CSRUsed[EXB] |= loopSpills;
-        addedUses = true;
-        DEBUG(if (ShrinkWrapDebugging >= Iterations)
-                dbgs() << "LOOP " << getBasicBlockName(MBB)
-                     << "(" << stringifyCSRegSet(loopSpills) << ")->"
-                     << getBasicBlockName(EXB) << "\n");
-        if (EXB->succ_size() > 1 || EXB->pred_size() > 1)
-          blks.push_back(EXB);
-      }
-    }
-  }
-  return addedUses;
-}
-
-/// calcSpillPlacements - determine which CSRs should be spilled
-/// in MBB using AnticIn sets of MBB's predecessors, keeping track
-/// of changes to spilled reg sets. Add MBB to the set of blocks
-/// that need to be processed for propagating use info to cover
-/// multi-entry/exit regions.
-///
-bool PEI::calcSpillPlacements(MachineBasicBlock* MBB,
-                              SmallVectorImpl<MachineBasicBlock *> &blks,
-                              CSRegBlockMap &prevSpills) {
-  bool placedSpills = false;
-  // Intersect (CSRegs - AnticIn[P]) for P in Predecessors(MBB)
-  CSRegSet anticInPreds;
-  SmallVector<MachineBasicBlock*, 4> predecessors;
-  for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
-         PE = MBB->pred_end(); PI != PE; ++PI) {
-    MachineBasicBlock* PRED = *PI;
-    if (PRED != MBB)
-      predecessors.push_back(PRED);
-  }
-  unsigned i = 0, e = predecessors.size();
-  if (i != e) {
-    MachineBasicBlock* PRED = predecessors[i];
-    anticInPreds = UsedCSRegs - AnticIn[PRED];
-    for (++i; i != e; ++i) {
-      PRED = predecessors[i];
-      anticInPreds &= (UsedCSRegs - AnticIn[PRED]);
-    }
-  } else {
-    // Handle uses in entry blocks (which have no predecessors).
-    // This is necessary because the DFA formulation assumes the
-    // entry and (multiple) exit nodes cannot have CSR uses, which
-    // is not the case in the real world.
-    anticInPreds = UsedCSRegs;
-  }
-  // Compute spills required at MBB:
-  CSRSave[MBB] |= (AnticIn[MBB] - AvailIn[MBB]) & anticInPreds;
-
-  if (! CSRSave[MBB].empty()) {
-    if (MBB == EntryBlock) {
-      for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri)
-        CSRRestore[ReturnBlocks[ri]] |= CSRSave[MBB];
-    } else {
-      // Reset all regs spilled in MBB that are also spilled in EntryBlock.
-      if (CSRSave[EntryBlock].intersects(CSRSave[MBB])) {
-        CSRSave[MBB] = CSRSave[MBB] - CSRSave[EntryBlock];
-      }
-    }
-  }
-  placedSpills = (CSRSave[MBB] != prevSpills[MBB]);
-  prevSpills[MBB] = CSRSave[MBB];
-  // Remember this block for adding restores to successor
-  // blocks for multi-entry region.
-  if (placedSpills)
-    blks.push_back(MBB);
-
-  DEBUG(if (! CSRSave[MBB].empty() && ShrinkWrapDebugging >= Iterations)
-          dbgs() << "SAVE[" << getBasicBlockName(MBB) << "] = "
-               << stringifyCSRegSet(CSRSave[MBB]) << "\n");
-
-  return placedSpills;
-}
-
-/// calcRestorePlacements - determine which CSRs should be restored
-/// in MBB using AvailOut sets of MBB's succcessors, keeping track
-/// of changes to restored reg sets. Add MBB to the set of blocks
-/// that need to be processed for propagating use info to cover
-/// multi-entry/exit regions.
-///
-bool PEI::calcRestorePlacements(MachineBasicBlock* MBB,
-                                SmallVectorImpl<MachineBasicBlock *> &blks,
-                                CSRegBlockMap &prevRestores) {
-  bool placedRestores = false;
-  // Intersect (CSRegs - AvailOut[S]) for S in Successors(MBB)
-  CSRegSet availOutSucc;
-  SmallVector<MachineBasicBlock*, 4> successors;
-  for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
-         SE = MBB->succ_end(); SI != SE; ++SI) {
-    MachineBasicBlock* SUCC = *SI;
-    if (SUCC != MBB)
-      successors.push_back(SUCC);
-  }
-  unsigned i = 0, e = successors.size();
-  if (i != e) {
-    MachineBasicBlock* SUCC = successors[i];
-    availOutSucc = UsedCSRegs - AvailOut[SUCC];
-    for (++i; i != e; ++i) {
-      SUCC = successors[i];
-      availOutSucc &= (UsedCSRegs - AvailOut[SUCC]);
-    }
-  } else {
-    if (! CSRUsed[MBB].empty() || ! AvailOut[MBB].empty()) {
-      // Handle uses in return blocks (which have no successors).
-      // This is necessary because the DFA formulation assumes the
-      // entry and (multiple) exit nodes cannot have CSR uses, which
-      // is not the case in the real world.
-      availOutSucc = UsedCSRegs;
-    }
-  }
-  // Compute restores required at MBB:
-  CSRRestore[MBB] |= (AvailOut[MBB] - AnticOut[MBB]) & availOutSucc;
-
-  // Postprocess restore placements at MBB.
-  // Remove the CSRs that are restored in the return blocks.
-  // Lest this be confusing, note that:
-  // CSRSave[EntryBlock] == CSRRestore[B] for all B in ReturnBlocks.
-  if (MBB->succ_size() && ! CSRRestore[MBB].empty()) {
-    if (! CSRSave[EntryBlock].empty())
-      CSRRestore[MBB] = CSRRestore[MBB] - CSRSave[EntryBlock];
-  }
-  placedRestores = (CSRRestore[MBB] != prevRestores[MBB]);
-  prevRestores[MBB] = CSRRestore[MBB];
-  // Remember this block for adding saves to predecessor
-  // blocks for multi-entry region.
-  if (placedRestores)
-    blks.push_back(MBB);
-
-  DEBUG(if (! CSRRestore[MBB].empty() && ShrinkWrapDebugging >= Iterations)
-          dbgs() << "RESTORE[" << getBasicBlockName(MBB) << "] = "
-               << stringifyCSRegSet(CSRRestore[MBB]) << "\n");
-
-  return placedRestores;
-}
-
-/// placeSpillsAndRestores - place spills and restores of CSRs
-/// used in MBBs in minimal regions that contain the uses.
-///
-void PEI::placeSpillsAndRestores(MachineFunction &Fn) {
-  CSRegBlockMap prevCSRSave;
-  CSRegBlockMap prevCSRRestore;
-  SmallVector<MachineBasicBlock*, 4> cvBlocks, ncvBlocks;
-  bool changed = true;
-  unsigned iterations = 0;
-
-  // Iterate computation of spill and restore placements in the MCFG until:
-  //   1. CSR use info has been fully propagated around the MCFG, and
-  //   2. computation of CSRSave[], CSRRestore[] reach fixed points.
-  while (changed) {
-    changed = false;
-    ++iterations;
-
-    DEBUG(if (ShrinkWrapDebugging >= Iterations)
-            dbgs() << "iter " << iterations
-                 << " --------------------------------------------------\n");
-
-    // Calculate CSR{Save,Restore} sets using Antic, Avail on the MCFG,
-    // which determines the placements of spills and restores.
-    // Keep track of changes to spills, restores in each iteration to
-    // minimize the total iterations.
-    bool SRChanged = false;
-    for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
-         MBBI != MBBE; ++MBBI) {
-      MachineBasicBlock* MBB = MBBI;
-
-      // Place spills for CSRs in MBB.
-      SRChanged |= calcSpillPlacements(MBB, cvBlocks, prevCSRSave);
-
-      // Place restores for CSRs in MBB.
-      SRChanged |= calcRestorePlacements(MBB, cvBlocks, prevCSRRestore);
-    }
-
-    // Add uses of CSRs used inside loops where needed.
-    changed |= addUsesForTopLevelLoops(cvBlocks);
-
-    // Add uses for CSRs spilled or restored at branch, join points.
-    if (changed || SRChanged) {
-      while (! cvBlocks.empty()) {
-        MachineBasicBlock* MBB = cvBlocks.pop_back_val();
-        changed |= addUsesForMEMERegion(MBB, ncvBlocks);
-      }
-      if (! ncvBlocks.empty()) {
-        cvBlocks = ncvBlocks;
-        ncvBlocks.clear();
-      }
-    }
-
-    if (changed) {
-      calculateAnticAvail(Fn);
-      CSRSave.clear();
-      CSRRestore.clear();
-    }
-  }
-
-  // Check for effectiveness:
-  //  SR0 = {r | r in CSRSave[EntryBlock], CSRRestore[RB], RB in ReturnBlocks}
-  //  numSRReduced = |(UsedCSRegs - SR0)|, approx. SR0 by CSRSave[EntryBlock]
-  // Gives a measure of how many CSR spills have been moved from EntryBlock
-  // to minimal regions enclosing their uses.
-  CSRegSet notSpilledInEntryBlock = (UsedCSRegs - CSRSave[EntryBlock]);
-  unsigned numSRReducedThisFunc = notSpilledInEntryBlock.count();
-  numSRReduced += numSRReducedThisFunc;
-  DEBUG(if (ShrinkWrapDebugging >= BasicInfo) {
-      dbgs() << "-----------------------------------------------------------\n";
-      dbgs() << "total iterations = " << iterations << " ( "
-           << Fn.getName()
-           << " " << numSRReducedThisFunc
-           << " " << Fn.size()
-           << " )\n";
-      dbgs() << "-----------------------------------------------------------\n";
-      dumpSRSets();
-      dbgs() << "-----------------------------------------------------------\n";
-      if (numSRReducedThisFunc)
-        verifySpillRestorePlacement();
-    });
-}
-
-// Debugging methods.
-#ifndef NDEBUG
-/// findFastExitPath - debugging method used to detect functions
-/// with at least one path from the entry block to a return block
-/// directly or which has a very small number of edges.
-///
-void PEI::findFastExitPath() {
-  if (! EntryBlock)
-    return;
-  // Fina a path from EntryBlock to any return block that does not branch:
-  //        Entry
-  //          |     ...
-  //          v      |
-  //         B1<-----+
-  //          |
-  //          v
-  //       Return
-  for (MachineBasicBlock::succ_iterator SI = EntryBlock->succ_begin(),
-         SE = EntryBlock->succ_end(); SI != SE; ++SI) {
-    MachineBasicBlock* SUCC = *SI;
-
-    // Assume positive, disprove existence of fast path.
-    HasFastExitPath = true;
-
-    // Check the immediate successors.
-    if (isReturnBlock(SUCC)) {
-      if (ShrinkWrapDebugging >= BasicInfo)
-        dbgs() << "Fast exit path: " << getBasicBlockName(EntryBlock)
-             << "->" << getBasicBlockName(SUCC) << "\n";
-      break;
-    }
-    // Traverse df from SUCC, look for a branch block.
-    std::string exitPath = getBasicBlockName(SUCC);
-    for (df_iterator<MachineBasicBlock*> BI = df_begin(SUCC),
-           BE = df_end(SUCC); BI != BE; ++BI) {
-      MachineBasicBlock* SBB = *BI;
-      // Reject paths with branch nodes.
-      if (SBB->succ_size() > 1) {
-        HasFastExitPath = false;
-        break;
-      }
-      exitPath += "->" + getBasicBlockName(SBB);
-    }
-    if (HasFastExitPath) {
-      if (ShrinkWrapDebugging >= BasicInfo)
-        dbgs() << "Fast exit path: " << getBasicBlockName(EntryBlock)
-             << "->" << exitPath << "\n";
-      break;
-    }
-  }
-}
-
-/// verifySpillRestorePlacement - check the current spill/restore
-/// sets for safety. Attempt to find spills without restores or
-/// restores without spills.
-/// Spills: walk df from each MBB in spill set ensuring that
-///         all CSRs spilled at MMBB are restored on all paths
-///         from MBB to all exit blocks.
-/// Restores: walk idf from each MBB in restore set ensuring that
-///           all CSRs restored at MBB are spilled on all paths
-///           reaching MBB.
-///
-void PEI::verifySpillRestorePlacement() {
-  unsigned numReturnBlocks = 0;
-  for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
-       MBBI != MBBE; ++MBBI) {
-    MachineBasicBlock* MBB = MBBI;
-    if (isReturnBlock(MBB) || MBB->succ_size() == 0)
-      ++numReturnBlocks;
-  }
-  for (CSRegBlockMap::iterator BI = CSRSave.begin(),
-         BE = CSRSave.end(); BI != BE; ++BI) {
-    MachineBasicBlock* MBB = BI->first;
-    CSRegSet spilled = BI->second;
-    CSRegSet restored;
-
-    if (spilled.empty())
-      continue;
-
-    DEBUG(dbgs() << "SAVE[" << getBasicBlockName(MBB) << "] = "
-                 << stringifyCSRegSet(spilled)
-                 << "  RESTORE[" << getBasicBlockName(MBB) << "] = "
-                 << stringifyCSRegSet(CSRRestore[MBB]) << "\n");
-
-    if (CSRRestore[MBB].intersects(spilled)) {
-      restored |= (CSRRestore[MBB] & spilled);
-    }
-
-    // Walk depth first from MBB to find restores of all CSRs spilled at MBB:
-    // we must find restores for all spills w/no intervening spills on all
-    // paths from MBB to all return blocks.
-    for (df_iterator<MachineBasicBlock*> BI = df_begin(MBB),
-           BE = df_end(MBB); BI != BE; ++BI) {
-      MachineBasicBlock* SBB = *BI;
-      if (SBB == MBB)
-        continue;
-      // Stop when we encounter spills of any CSRs spilled at MBB that
-      // have not yet been seen to be restored.
-      if (CSRSave[SBB].intersects(spilled) &&
-          !restored.contains(CSRSave[SBB] & spilled))
-        break;
-      // Collect the CSRs spilled at MBB that are restored
-      // at this DF successor of MBB.
-      if (CSRRestore[SBB].intersects(spilled))
-        restored |= (CSRRestore[SBB] & spilled);
-      // If we are at a retun block, check that the restores
-      // we have seen so far exhaust the spills at MBB, then
-      // reset the restores.
-      if (isReturnBlock(SBB) || SBB->succ_size() == 0) {
-        if (restored != spilled) {
-          CSRegSet notRestored = (spilled - restored);
-          DEBUG(dbgs() << MF->getName() << ": "
-                       << stringifyCSRegSet(notRestored)
-                       << " spilled at " << getBasicBlockName(MBB)
-                       << " are never restored on path to return "
-                       << getBasicBlockName(SBB) << "\n");
-        }
-        restored.clear();
-      }
-    }
-  }
-
-  // Check restore placements.
-  for (CSRegBlockMap::iterator BI = CSRRestore.begin(),
-         BE = CSRRestore.end(); BI != BE; ++BI) {
-    MachineBasicBlock* MBB = BI->first;
-    CSRegSet restored = BI->second;
-    CSRegSet spilled;
-
-    if (restored.empty())
-      continue;
-
-    DEBUG(dbgs() << "SAVE[" << getBasicBlockName(MBB) << "] = "
-                 << stringifyCSRegSet(CSRSave[MBB])
-                 << "  RESTORE[" << getBasicBlockName(MBB) << "] = "
-                 << stringifyCSRegSet(restored) << "\n");
-
-    if (CSRSave[MBB].intersects(restored)) {
-      spilled |= (CSRSave[MBB] & restored);
-    }
-    // Walk inverse depth first from MBB to find spills of all
-    // CSRs restored at MBB:
-    for (idf_iterator<MachineBasicBlock*> BI = idf_begin(MBB),
-           BE = idf_end(MBB); BI != BE; ++BI) {
-      MachineBasicBlock* PBB = *BI;
-      if (PBB == MBB)
-        continue;
-      // Stop when we encounter restores of any CSRs restored at MBB that
-      // have not yet been seen to be spilled.
-      if (CSRRestore[PBB].intersects(restored) &&
-          !spilled.contains(CSRRestore[PBB] & restored))
-        break;
-      // Collect the CSRs restored at MBB that are spilled
-      // at this DF predecessor of MBB.
-      if (CSRSave[PBB].intersects(restored))
-        spilled |= (CSRSave[PBB] & restored);
-    }
-    if (spilled != restored) {
-      CSRegSet notSpilled = (restored - spilled);
-      DEBUG(dbgs() << MF->getName() << ": "
-                   << stringifyCSRegSet(notSpilled)
-                   << " restored at " << getBasicBlockName(MBB)
-                   << " are never spilled\n");
-    }
-  }
-}
-
-// Debugging print methods.
-std::string PEI::getBasicBlockName(const MachineBasicBlock* MBB) {
-  if (!MBB)
-    return "";
-
-  if (MBB->getBasicBlock())
-    return MBB->getBasicBlock()->getName().str();
-
-  std::ostringstream name;
-  name << "_MBB_" << MBB->getNumber();
-  return name.str();
-}
-
-std::string PEI::stringifyCSRegSet(const CSRegSet& s) {
-  const TargetRegisterInfo* TRI = MF->getTarget().getRegisterInfo();
-  const std::vector<CalleeSavedInfo> &CSI =
-    MF->getFrameInfo()->getCalleeSavedInfo();
-
-  std::ostringstream srep;
-  if (CSI.size() == 0) {
-    srep << "[]";
-    return srep.str();
-  }
-  srep << "[";
-  CSRegSet::iterator I = s.begin(), E = s.end();
-  if (I != E) {
-    unsigned reg = CSI[*I].getReg();
-    srep << TRI->getName(reg);
-    for (++I; I != E; ++I) {
-      reg = CSI[*I].getReg();
-      srep << ",";
-      srep << TRI->getName(reg);
-    }
-  }
-  srep << "]";
-  return srep.str();
-}
-
-void PEI::dumpSet(const CSRegSet& s) {
-  DEBUG(dbgs() << stringifyCSRegSet(s) << "\n");
-}
-
-void PEI::dumpUsed(MachineBasicBlock* MBB) {
-  DEBUG({
-      if (MBB)
-        dbgs() << "CSRUsed[" << getBasicBlockName(MBB) << "] = "
-               << stringifyCSRegSet(CSRUsed[MBB])  << "\n";
-    });
-}
-
-void PEI::dumpAllUsed() {
-    for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
-         MBBI != MBBE; ++MBBI) {
-      MachineBasicBlock* MBB = MBBI;
-      dumpUsed(MBB);
-    }
-}
-
-void PEI::dumpSets(MachineBasicBlock* MBB) {
-  DEBUG({
-      if (MBB)
-        dbgs() << getBasicBlockName(MBB)           << " | "
-               << stringifyCSRegSet(CSRUsed[MBB])  << " | "
-               << stringifyCSRegSet(AnticIn[MBB])  << " | "
-               << stringifyCSRegSet(AnticOut[MBB]) << " | "
-               << stringifyCSRegSet(AvailIn[MBB])  << " | "
-               << stringifyCSRegSet(AvailOut[MBB]) << "\n";
-    });
-}
-
-void PEI::dumpSets1(MachineBasicBlock* MBB) {
-  DEBUG({
-      if (MBB)
-        dbgs() << getBasicBlockName(MBB)             << " | "
-               << stringifyCSRegSet(CSRUsed[MBB])    << " | "
-               << stringifyCSRegSet(AnticIn[MBB])    << " | "
-               << stringifyCSRegSet(AnticOut[MBB])   << " | "
-               << stringifyCSRegSet(AvailIn[MBB])    << " | "
-               << stringifyCSRegSet(AvailOut[MBB])   << " | "
-               << stringifyCSRegSet(CSRSave[MBB])    << " | "
-               << stringifyCSRegSet(CSRRestore[MBB]) << "\n";
-    });
-}
-
-void PEI::dumpAllSets() {
-    for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
-         MBBI != MBBE; ++MBBI) {
-      MachineBasicBlock* MBB = MBBI;
-      dumpSets1(MBB);
-    }
-}
-
-void PEI::dumpSRSets() {
-  DEBUG({
-      for (MachineFunction::iterator MBB = MF->begin(), E = MF->end();
-           MBB != E; ++MBB) {
-        if (!CSRSave[MBB].empty()) {
-          dbgs() << "SAVE[" << getBasicBlockName(MBB) << "] = "
-                 << stringifyCSRegSet(CSRSave[MBB]);
-          if (CSRRestore[MBB].empty())
-            dbgs() << '\n';
-        }
-
-        if (!CSRRestore[MBB].empty() && !CSRSave[MBB].empty())
-          dbgs() << "    "
-                 << "RESTORE[" << getBasicBlockName(MBB) << "] = "
-                 << stringifyCSRegSet(CSRRestore[MBB]) << "\n";
-      }
-    });
-}
-#endif