1 files changed, 0 insertions, 681 deletions

diff --git a/contrib/llvm/lib/CodeGen/GlobalMerge.cpp b/contrib/llvm/lib/CodeGen/GlobalMerge.cpp
deleted file mode 100644
index 09201c2e7bae..000000000000
--- a/contrib/llvm/lib/CodeGen/GlobalMerge.cpp
+++ /dev/null
@@ -1,681 +0,0 @@
-//===- GlobalMerge.cpp - Internal globals merging -------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This pass merges globals with internal linkage into one. This way all the
-// globals which were merged into a biggest one can be addressed using offsets
-// from the same base pointer (no need for separate base pointer for each of the
-// global). Such a transformation can significantly reduce the register pressure
-// when many globals are involved.
-//
-// For example, consider the code which touches several global variables at
-// once:
-//
-// static int foo[N], bar[N], baz[N];
-//
-// for (i = 0; i < N; ++i) {
-//    foo[i] = bar[i] * baz[i];
-// }
-//
-//  On ARM the addresses of 3 arrays should be kept in the registers, thus
-//  this code has quite large register pressure (loop body):
-//
-//  ldr     r1, [r5], #4
-//  ldr     r2, [r6], #4
-//  mul     r1, r2, r1
-//  str     r1, [r0], #4
-//
-//  Pass converts the code to something like:
-//
-//  static struct {
-//    int foo[N];
-//    int bar[N];
-//    int baz[N];
-//  } merged;
-//
-//  for (i = 0; i < N; ++i) {
-//    merged.foo[i] = merged.bar[i] * merged.baz[i];
-//  }
-//
-//  and in ARM code this becomes:
-//
-//  ldr     r0, [r5, #40]
-//  ldr     r1, [r5, #80]
-//  mul     r0, r1, r0
-//  str     r0, [r5], #4
-//
-//  note that we saved 2 registers here almostly "for free".
-//
-// However, merging globals can have tradeoffs:
-// - it confuses debuggers, tools, and users
-// - it makes linker optimizations less useful (order files, LOHs, ...)
-// - it forces usage of indexed addressing (which isn't necessarily "free")
-// - it can increase register pressure when the uses are disparate enough.
-//
-// We use heuristics to discover the best global grouping we can (cf cl::opts).
-//
-// ===---------------------------------------------------------------------===//
-
-#include "llvm/ADT/BitVector.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/ADT/Triple.h"
-#include "llvm/ADT/Twine.h"
-#include "llvm/CodeGen/Passes.h"
-#include "llvm/IR/BasicBlock.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/DataLayout.h"
-#include "llvm/IR/DerivedTypes.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/GlobalAlias.h"
-#include "llvm/IR/GlobalValue.h"
-#include "llvm/IR/GlobalVariable.h"
-#include "llvm/IR/Instruction.h"
-#include "llvm/IR/Module.h"
-#include "llvm/IR/Type.h"
-#include "llvm/IR/Use.h"
-#include "llvm/IR/User.h"
-#include "llvm/Pass.h"
-#include "llvm/Support/Casting.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetLoweringObjectFile.h"
-#include "llvm/Target/TargetMachine.h"
-#include <algorithm>
-#include <cassert>
-#include <cstddef>
-#include <cstdint>
-#include <string>
-#include <vector>
-
-using namespace llvm;
-
-#define DEBUG_TYPE "global-merge"
-
-// FIXME: This is only useful as a last-resort way to disable the pass.
-static cl::opt<bool>
-EnableGlobalMerge("enable-global-merge", cl::Hidden,
-                  cl::desc("Enable the global merge pass"),
-                  cl::init(true));
-
-static cl::opt<unsigned>
-GlobalMergeMaxOffset("global-merge-max-offset", cl::Hidden,
-                     cl::desc("Set maximum offset for global merge pass"),
-                     cl::init(0));
-
-static cl::opt<bool> GlobalMergeGroupByUse(
-    "global-merge-group-by-use", cl::Hidden,
-    cl::desc("Improve global merge pass to look at uses"), cl::init(true));
-
-static cl::opt<bool> GlobalMergeIgnoreSingleUse(
-    "global-merge-ignore-single-use", cl::Hidden,
-    cl::desc("Improve global merge pass to ignore globals only used alone"),
-    cl::init(true));
-
-static cl::opt<bool>
-EnableGlobalMergeOnConst("global-merge-on-const", cl::Hidden,
-                         cl::desc("Enable global merge pass on constants"),
-                         cl::init(false));
-
-// FIXME: this could be a transitional option, and we probably need to remove
-// it if only we are sure this optimization could always benefit all targets.
-static cl::opt<cl::boolOrDefault>
-EnableGlobalMergeOnExternal("global-merge-on-external", cl::Hidden,
-     cl::desc("Enable global merge pass on external linkage"));
-
-STATISTIC(NumMerged, "Number of globals merged");
-
-namespace {
-
-  class GlobalMerge : public FunctionPass {
-    const TargetMachine *TM = nullptr;
-
-    // FIXME: Infer the maximum possible offset depending on the actual users
-    // (these max offsets are different for the users inside Thumb or ARM
-    // functions), see the code that passes in the offset in the ARM backend
-    // for more information.
-    unsigned MaxOffset;
-
-    /// Whether we should try to optimize for size only.
-    /// Currently, this applies a dead simple heuristic: only consider globals
-    /// used in minsize functions for merging.
-    /// FIXME: This could learn about optsize, and be used in the cost model.
-    bool OnlyOptimizeForSize = false;
-
-    /// Whether we should merge global variables that have external linkage.
-    bool MergeExternalGlobals = false;
-
-    bool IsMachO;
-
-    bool doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
-                 Module &M, bool isConst, unsigned AddrSpace) const;
-
-    /// Merge everything in \p Globals for which the corresponding bit
-    /// in \p GlobalSet is set.
-    bool doMerge(const SmallVectorImpl<GlobalVariable *> &Globals,
-                 const BitVector &GlobalSet, Module &M, bool isConst,
-                 unsigned AddrSpace) const;
-
-    /// Check if the given variable has been identified as must keep
-    /// \pre setMustKeepGlobalVariables must have been called on the Module that
-    ///      contains GV
-    bool isMustKeepGlobalVariable(const GlobalVariable *GV) const {
-      return MustKeepGlobalVariables.count(GV);
-    }
-
-    /// Collect every variables marked as "used" or used in a landing pad
-    /// instruction for this Module.
-    void setMustKeepGlobalVariables(Module &M);
-
-    /// Collect every variables marked as "used"
-    void collectUsedGlobalVariables(Module &M, StringRef Name);
-
-    /// Keep track of the GlobalVariable that must not be merged away
-    SmallPtrSet<const GlobalVariable *, 16> MustKeepGlobalVariables;
-
-  public:
-    static char ID;             // Pass identification, replacement for typeid.
-
-    explicit GlobalMerge()
-        : FunctionPass(ID), MaxOffset(GlobalMergeMaxOffset) {
-      initializeGlobalMergePass(*PassRegistry::getPassRegistry());
-    }
-
-    explicit GlobalMerge(const TargetMachine *TM, unsigned MaximalOffset,
-                         bool OnlyOptimizeForSize, bool MergeExternalGlobals)
-        : FunctionPass(ID), TM(TM), MaxOffset(MaximalOffset),
-          OnlyOptimizeForSize(OnlyOptimizeForSize),
-          MergeExternalGlobals(MergeExternalGlobals) {
-      initializeGlobalMergePass(*PassRegistry::getPassRegistry());
-    }
-
-    bool doInitialization(Module &M) override;
-    bool runOnFunction(Function &F) override;
-    bool doFinalization(Module &M) override;
-
-    StringRef getPassName() const override { return "Merge internal globals"; }
-
-    void getAnalysisUsage(AnalysisUsage &AU) const override {
-      AU.setPreservesCFG();
-      FunctionPass::getAnalysisUsage(AU);
-    }
-  };
-
-} // end anonymous namespace
-
-char GlobalMerge::ID = 0;
-
-INITIALIZE_PASS(GlobalMerge, DEBUG_TYPE, "Merge global variables", false, false)
-
-bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
-                          Module &M, bool isConst, unsigned AddrSpace) const {
-  auto &DL = M.getDataLayout();
-  // FIXME: Find better heuristics
-  llvm::stable_sort(
-      Globals, [&DL](const GlobalVariable *GV1, const GlobalVariable *GV2) {
-        return DL.getTypeAllocSize(GV1->getValueType()) <
-               DL.getTypeAllocSize(GV2->getValueType());
-      });
-
-  // If we want to just blindly group all globals together, do so.
-  if (!GlobalMergeGroupByUse) {
-    BitVector AllGlobals(Globals.size());
-    AllGlobals.set();
-    return doMerge(Globals, AllGlobals, M, isConst, AddrSpace);
-  }
-
-  // If we want to be smarter, look at all uses of each global, to try to
-  // discover all sets of globals used together, and how many times each of
-  // these sets occurred.
-  //
-  // Keep this reasonably efficient, by having an append-only list of all sets
-  // discovered so far (UsedGlobalSet), and mapping each "together-ness" unit of
-  // code (currently, a Function) to the set of globals seen so far that are
-  // used together in that unit (GlobalUsesByFunction).
-  //
-  // When we look at the Nth global, we know that any new set is either:
-  // - the singleton set {N}, containing this global only, or
-  // - the union of {N} and a previously-discovered set, containing some
-  //   combination of the previous N-1 globals.
-  // Using that knowledge, when looking at the Nth global, we can keep:
-  // - a reference to the singleton set {N} (CurGVOnlySetIdx)
-  // - a list mapping each previous set to its union with {N} (EncounteredUGS),
-  //   if it actually occurs.
-
-  // We keep track of the sets of globals used together "close enough".
-  struct UsedGlobalSet {
-    BitVector Globals;
-    unsigned UsageCount = 1;
-
-    UsedGlobalSet(size_t Size) : Globals(Size) {}
-  };
-
-  // Each set is unique in UsedGlobalSets.
-  std::vector<UsedGlobalSet> UsedGlobalSets;
-
-  // Avoid repeating the create-global-set pattern.
-  auto CreateGlobalSet = [&]() -> UsedGlobalSet & {
-    UsedGlobalSets.emplace_back(Globals.size());
-    return UsedGlobalSets.back();
-  };
-
-  // The first set is the empty set.
-  CreateGlobalSet().UsageCount = 0;
-
-  // We define "close enough" to be "in the same function".
-  // FIXME: Grouping uses by function is way too aggressive, so we should have
-  // a better metric for distance between uses.
-  // The obvious alternative would be to group by BasicBlock, but that's in
-  // turn too conservative..
-  // Anything in between wouldn't be trivial to compute, so just stick with
-  // per-function grouping.
-
-  // The value type is an index into UsedGlobalSets.
-  // The default (0) conveniently points to the empty set.
-  DenseMap<Function *, size_t /*UsedGlobalSetIdx*/> GlobalUsesByFunction;
-
-  // Now, look at each merge-eligible global in turn.
-
-  // Keep track of the sets we already encountered to which we added the
-  // current global.
-  // Each element matches the same-index element in UsedGlobalSets.
-  // This lets us efficiently tell whether a set has already been expanded to
-  // include the current global.
-  std::vector<size_t> EncounteredUGS;
-
-  for (size_t GI = 0, GE = Globals.size(); GI != GE; ++GI) {
-    GlobalVariable *GV = Globals[GI];
-
-    // Reset the encountered sets for this global...
-    std::fill(EncounteredUGS.begin(), EncounteredUGS.end(), 0);
-    // ...and grow it in case we created new sets for the previous global.
-    EncounteredUGS.resize(UsedGlobalSets.size());
-
-    // We might need to create a set that only consists of the current global.
-    // Keep track of its index into UsedGlobalSets.
-    size_t CurGVOnlySetIdx = 0;
-
-    // For each global, look at all its Uses.
-    for (auto &U : GV->uses()) {
-      // This Use might be a ConstantExpr.  We're interested in Instruction
-      // users, so look through ConstantExpr...
-      Use *UI, *UE;
-      if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U.getUser())) {
-        if (CE->use_empty())
-          continue;
-        UI = &*CE->use_begin();
-        UE = nullptr;
-      } else if (isa<Instruction>(U.getUser())) {
-        UI = &U;
-        UE = UI->getNext();
-      } else {
-        continue;
-      }
-
-      // ...to iterate on all the instruction users of the global.
-      // Note that we iterate on Uses and not on Users to be able to getNext().
-      for (; UI != UE; UI = UI->getNext()) {
-        Instruction *I = dyn_cast<Instruction>(UI->getUser());
-        if (!I)
-          continue;
-
-        Function *ParentFn = I->getParent()->getParent();
-
-        // If we're only optimizing for size, ignore non-minsize functions.
-        if (OnlyOptimizeForSize && !ParentFn->hasMinSize())
-          continue;
-
-        size_t UGSIdx = GlobalUsesByFunction[ParentFn];
-
-        // If this is the first global the basic block uses, map it to the set
-        // consisting of this global only.
-        if (!UGSIdx) {
-          // If that set doesn't exist yet, create it.
-          if (!CurGVOnlySetIdx) {
-            CurGVOnlySetIdx = UsedGlobalSets.size();
-            CreateGlobalSet().Globals.set(GI);
-          } else {
-            ++UsedGlobalSets[CurGVOnlySetIdx].UsageCount;
-          }
-
-          GlobalUsesByFunction[ParentFn] = CurGVOnlySetIdx;
-          continue;
-        }
-
-        // If we already encountered this BB, just increment the counter.
-        if (UsedGlobalSets[UGSIdx].Globals.test(GI)) {
-          ++UsedGlobalSets[UGSIdx].UsageCount;
-          continue;
-        }
-
-        // If not, the previous set wasn't actually used in this function.
-        --UsedGlobalSets[UGSIdx].UsageCount;
-
-        // If we already expanded the previous set to include this global, just
-        // reuse that expanded set.
-        if (size_t ExpandedIdx = EncounteredUGS[UGSIdx]) {
-          ++UsedGlobalSets[ExpandedIdx].UsageCount;
-          GlobalUsesByFunction[ParentFn] = ExpandedIdx;
-          continue;
-        }
-
-        // If not, create a new set consisting of the union of the previous set
-        // and this global.  Mark it as encountered, so we can reuse it later.
-        GlobalUsesByFunction[ParentFn] = EncounteredUGS[UGSIdx] =
-            UsedGlobalSets.size();
-
-        UsedGlobalSet &NewUGS = CreateGlobalSet();
-        NewUGS.Globals.set(GI);
-        NewUGS.Globals |= UsedGlobalSets[UGSIdx].Globals;
-      }
-    }
-  }
-
-  // Now we found a bunch of sets of globals used together.  We accumulated
-  // the number of times we encountered the sets (i.e., the number of blocks
-  // that use that exact set of globals).
-  //
-  // Multiply that by the size of the set to give us a crude profitability
-  // metric.
-  llvm::stable_sort(UsedGlobalSets,
-                    [](const UsedGlobalSet &UGS1, const UsedGlobalSet &UGS2) {
-                      return UGS1.Globals.count() * UGS1.UsageCount <
-                             UGS2.Globals.count() * UGS2.UsageCount;
-                    });
-
-  // We can choose to merge all globals together, but ignore globals never used
-  // with another global.  This catches the obviously non-profitable cases of
-  // having a single global, but is aggressive enough for any other case.
-  if (GlobalMergeIgnoreSingleUse) {
-    BitVector AllGlobals(Globals.size());
-    for (size_t i = 0, e = UsedGlobalSets.size(); i != e; ++i) {
-      const UsedGlobalSet &UGS = UsedGlobalSets[e - i - 1];
-      if (UGS.UsageCount == 0)
-        continue;
-      if (UGS.Globals.count() > 1)
-        AllGlobals |= UGS.Globals;
-    }
-    return doMerge(Globals, AllGlobals, M, isConst, AddrSpace);
-  }
-
-  // Starting from the sets with the best (=biggest) profitability, find a
-  // good combination.
-  // The ideal (and expensive) solution can only be found by trying all
-  // combinations, looking for the one with the best profitability.
-  // Don't be smart about it, and just pick the first compatible combination,
-  // starting with the sets with the best profitability.
-  BitVector PickedGlobals(Globals.size());
-  bool Changed = false;
-
-  for (size_t i = 0, e = UsedGlobalSets.size(); i != e; ++i) {
-    const UsedGlobalSet &UGS = UsedGlobalSets[e - i - 1];
-    if (UGS.UsageCount == 0)
-      continue;
-    if (PickedGlobals.anyCommon(UGS.Globals))
-      continue;
-    PickedGlobals |= UGS.Globals;
-    // If the set only contains one global, there's no point in merging.
-    // Ignore the global for inclusion in other sets though, so keep it in
-    // PickedGlobals.
-    if (UGS.Globals.count() < 2)
-      continue;
-    Changed |= doMerge(Globals, UGS.Globals, M, isConst, AddrSpace);
-  }
-
-  return Changed;
-}
-
-bool GlobalMerge::doMerge(const SmallVectorImpl<GlobalVariable *> &Globals,
-                          const BitVector &GlobalSet, Module &M, bool isConst,
-                          unsigned AddrSpace) const {
-  assert(Globals.size() > 1);
-
-  Type *Int32Ty = Type::getInt32Ty(M.getContext());
-  Type *Int8Ty = Type::getInt8Ty(M.getContext());
-  auto &DL = M.getDataLayout();
-
-  LLVM_DEBUG(dbgs() << " Trying to merge set, starts with #"
-                    << GlobalSet.find_first() << "\n");
-
-  bool Changed = false;
-  ssize_t i = GlobalSet.find_first();
-  while (i != -1) {
-    ssize_t j = 0;
-    uint64_t MergedSize = 0;
-    std::vector<Type*> Tys;
-    std::vector<Constant*> Inits;
-    std::vector<unsigned> StructIdxs;
-
-    bool HasExternal = false;
-    StringRef FirstExternalName;
-    unsigned MaxAlign = 1;
-    unsigned CurIdx = 0;
-    for (j = i; j != -1; j = GlobalSet.find_next(j)) {
-      Type *Ty = Globals[j]->getValueType();
-
-      // Make sure we use the same alignment AsmPrinter would use.
-      unsigned Align = DL.getPreferredAlignment(Globals[j]);
-      unsigned Padding = alignTo(MergedSize, Align) - MergedSize;
-      MergedSize += Padding;
-      MergedSize += DL.getTypeAllocSize(Ty);
-      if (MergedSize > MaxOffset) {
-        break;
-      }
-      if (Padding) {
-        Tys.push_back(ArrayType::get(Int8Ty, Padding));
-        Inits.push_back(ConstantAggregateZero::get(Tys.back()));
-        ++CurIdx;
-      }
-      Tys.push_back(Ty);
-      Inits.push_back(Globals[j]->getInitializer());
-      StructIdxs.push_back(CurIdx++);
-
-      MaxAlign = std::max(MaxAlign, Align);
-
-      if (Globals[j]->hasExternalLinkage() && !HasExternal) {
-        HasExternal = true;
-        FirstExternalName = Globals[j]->getName();
-      }
-    }
-
-    // Exit early if there is only one global to merge.
-    if (Tys.size() < 2) {
-      i = j;
-      continue;
-    }
-
-    // If merged variables doesn't have external linkage, we needn't to expose
-    // the symbol after merging.
-    GlobalValue::LinkageTypes Linkage = HasExternal
-                                            ? GlobalValue::ExternalLinkage
-                                            : GlobalValue::InternalLinkage;
-    // Use a packed struct so we can control alignment.
-    StructType *MergedTy = StructType::get(M.getContext(), Tys, true);
-    Constant *MergedInit = ConstantStruct::get(MergedTy, Inits);
-
-    // On Darwin external linkage needs to be preserved, otherwise
-    // dsymutil cannot preserve the debug info for the merged
-    // variables.  If they have external linkage, use the symbol name
-    // of the first variable merged as the suffix of global symbol
-    // name.  This avoids a link-time naming conflict for the
-    // _MergedGlobals symbols.
-    Twine MergedName =
-        (IsMachO && HasExternal)
-            ? "_MergedGlobals_" + FirstExternalName
-            : "_MergedGlobals";
-    auto MergedLinkage = IsMachO ? Linkage : GlobalValue::PrivateLinkage;
-    auto *MergedGV = new GlobalVariable(
-        M, MergedTy, isConst, MergedLinkage, MergedInit, MergedName, nullptr,
-        GlobalVariable::NotThreadLocal, AddrSpace);
-
-    MergedGV->setAlignment(MaxAlign);
-    MergedGV->setSection(Globals[i]->getSection());
-
-    const StructLayout *MergedLayout = DL.getStructLayout(MergedTy);
-    for (ssize_t k = i, idx = 0; k != j; k = GlobalSet.find_next(k), ++idx) {
-      GlobalValue::LinkageTypes Linkage = Globals[k]->getLinkage();
-      std::string Name = Globals[k]->getName();
-      GlobalValue::DLLStorageClassTypes DLLStorage =
-          Globals[k]->getDLLStorageClass();
-
-      // Copy metadata while adjusting any debug info metadata by the original
-      // global's offset within the merged global.
-      MergedGV->copyMetadata(Globals[k],
-                             MergedLayout->getElementOffset(StructIdxs[idx]));
-
-      Constant *Idx[2] = {
-          ConstantInt::get(Int32Ty, 0),
-          ConstantInt::get(Int32Ty, StructIdxs[idx]),
-      };
-      Constant *GEP =
-          ConstantExpr::getInBoundsGetElementPtr(MergedTy, MergedGV, Idx);
-      Globals[k]->replaceAllUsesWith(GEP);
-      Globals[k]->eraseFromParent();
-
-      // When the linkage is not internal we must emit an alias for the original
-      // variable name as it may be accessed from another object. On non-Mach-O
-      // we can also emit an alias for internal linkage as it's safe to do so.
-      // It's not safe on Mach-O as the alias (and thus the portion of the
-      // MergedGlobals variable) may be dead stripped at link time.
-      if (Linkage != GlobalValue::InternalLinkage || !IsMachO) {
-        GlobalAlias *GA = GlobalAlias::create(Tys[StructIdxs[idx]], AddrSpace,
-                                              Linkage, Name, GEP, &M);
-        GA->setDLLStorageClass(DLLStorage);
-      }
-
-      NumMerged++;
-    }
-    Changed = true;
-    i = j;
-  }
-
-  return Changed;
-}
-
-void GlobalMerge::collectUsedGlobalVariables(Module &M, StringRef Name) {
-  // Extract global variables from llvm.used array
-  const GlobalVariable *GV = M.getGlobalVariable(Name);
-  if (!GV || !GV->hasInitializer()) return;
-
-  // Should be an array of 'i8*'.
-  const ConstantArray *InitList = cast<ConstantArray>(GV->getInitializer());
-
-  for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i)
-    if (const GlobalVariable *G =
-        dyn_cast<GlobalVariable>(InitList->getOperand(i)->stripPointerCasts()))
-      MustKeepGlobalVariables.insert(G);
-}
-
-void GlobalMerge::setMustKeepGlobalVariables(Module &M) {
-  collectUsedGlobalVariables(M, "llvm.used");
-  collectUsedGlobalVariables(M, "llvm.compiler.used");
-
-  for (Function &F : M) {
-    for (BasicBlock &BB : F) {
-      Instruction *Pad = BB.getFirstNonPHI();
-      if (!Pad->isEHPad())
-        continue;
-
-      // Keep globals used by landingpads and catchpads.
-      for (const Use &U : Pad->operands()) {
-        if (const GlobalVariable *GV =
-                dyn_cast<GlobalVariable>(U->stripPointerCasts()))
-          MustKeepGlobalVariables.insert(GV);
-      }
-    }
-  }
-}
-
-bool GlobalMerge::doInitialization(Module &M) {
-  if (!EnableGlobalMerge)
-    return false;
-
-  IsMachO = Triple(M.getTargetTriple()).isOSBinFormatMachO();
-
-  auto &DL = M.getDataLayout();
-  DenseMap<std::pair<unsigned, StringRef>, SmallVector<GlobalVariable *, 16>>
-      Globals, ConstGlobals, BSSGlobals;
-  bool Changed = false;
-  setMustKeepGlobalVariables(M);
-
-  // Grab all non-const globals.
-  for (auto &GV : M.globals()) {
-    // Merge is safe for "normal" internal or external globals only
-    if (GV.isDeclaration() || GV.isThreadLocal() || GV.hasImplicitSection())
-      continue;
-
-    // It's not safe to merge globals that may be preempted
-    if (TM && !TM->shouldAssumeDSOLocal(M, &GV))
-      continue;
-
-    if (!(MergeExternalGlobals && GV.hasExternalLinkage()) &&
-        !GV.hasInternalLinkage())
-      continue;
-
-    PointerType *PT = dyn_cast<PointerType>(GV.getType());
-    assert(PT && "Global variable is not a pointer!");
-
-    unsigned AddressSpace = PT->getAddressSpace();
-    StringRef Section = GV.getSection();
-
-    // Ignore all 'special' globals.
-    if (GV.getName().startswith("llvm.") ||
-        GV.getName().startswith(".llvm."))
-      continue;
-
-    // Ignore all "required" globals:
-    if (isMustKeepGlobalVariable(&GV))
-      continue;
-
-    Type *Ty = GV.getValueType();
-    if (DL.getTypeAllocSize(Ty) < MaxOffset) {
-      if (TM &&
-          TargetLoweringObjectFile::getKindForGlobal(&GV, *TM).isBSS())
-        BSSGlobals[{AddressSpace, Section}].push_back(&GV);
-      else if (GV.isConstant())
-        ConstGlobals[{AddressSpace, Section}].push_back(&GV);
-      else
-        Globals[{AddressSpace, Section}].push_back(&GV);
-    }
-  }
-
-  for (auto &P : Globals)
-    if (P.second.size() > 1)
-      Changed |= doMerge(P.second, M, false, P.first.first);
-
-  for (auto &P : BSSGlobals)
-    if (P.second.size() > 1)
-      Changed |= doMerge(P.second, M, false, P.first.first);
-
-  if (EnableGlobalMergeOnConst)
-    for (auto &P : ConstGlobals)
-      if (P.second.size() > 1)
-        Changed |= doMerge(P.second, M, true, P.first.first);
-
-  return Changed;
-}
-
-bool GlobalMerge::runOnFunction(Function &F) {
-  return false;
-}
-
-bool GlobalMerge::doFinalization(Module &M) {
-  MustKeepGlobalVariables.clear();
-  return false;
-}
-
-Pass *llvm::createGlobalMergePass(const TargetMachine *TM, unsigned Offset,
-                                  bool OnlyOptimizeForSize,
-                                  bool MergeExternalByDefault) {
-  bool MergeExternal = (EnableGlobalMergeOnExternal == cl::BOU_UNSET) ?
-    MergeExternalByDefault : (EnableGlobalMergeOnExternal == cl::BOU_TRUE);
-  return new GlobalMerge(TM, Offset, OnlyOptimizeForSize, MergeExternal);
-}