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diff --git a/contrib/llvm/lib/CodeGen/ShadowStackGCLowering.cpp b/contrib/llvm/lib/CodeGen/ShadowStackGCLowering.cpp
deleted file mode 100644
index 17a4d76c4c80..000000000000
--- a/contrib/llvm/lib/CodeGen/ShadowStackGCLowering.cpp
+++ /dev/null
@@ -1,372 +0,0 @@
-//===- ShadowStackGCLowering.cpp - Custom lowering for shadow-stack gc ----===//
-//
-// 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 file contains the custom lowering code required by the shadow-stack GC
-// strategy.
-//
-// This pass implements the code transformation described in this paper:
-//   "Accurate Garbage Collection in an Uncooperative Environment"
-//   Fergus Henderson, ISMM, 2002
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringExtras.h"
-#include "llvm/CodeGen/Passes.h"
-#include "llvm/IR/BasicBlock.h"
-#include "llvm/IR/Constant.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/DerivedTypes.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/GlobalValue.h"
-#include "llvm/IR/GlobalVariable.h"
-#include "llvm/IR/IRBuilder.h"
-#include "llvm/IR/Instructions.h"
-#include "llvm/IR/IntrinsicInst.h"
-#include "llvm/IR/Intrinsics.h"
-#include "llvm/IR/Module.h"
-#include "llvm/IR/Type.h"
-#include "llvm/IR/Value.h"
-#include "llvm/Pass.h"
-#include "llvm/Support/Casting.h"
-#include "llvm/Transforms/Utils/EscapeEnumerator.h"
-#include <cassert>
-#include <cstddef>
-#include <string>
-#include <utility>
-#include <vector>
-
-using namespace llvm;
-
-#define DEBUG_TYPE "shadow-stack-gc-lowering"
-
-namespace {
-
-class ShadowStackGCLowering : public FunctionPass {
-  /// RootChain - This is the global linked-list that contains the chain of GC
-  /// roots.
-  GlobalVariable *Head = nullptr;
-
-  /// StackEntryTy - Abstract type of a link in the shadow stack.
-  StructType *StackEntryTy = nullptr;
-  StructType *FrameMapTy = nullptr;
-
-  /// Roots - GC roots in the current function. Each is a pair of the
-  /// intrinsic call and its corresponding alloca.
-  std::vector<std::pair<CallInst *, AllocaInst *>> Roots;
-
-public:
-  static char ID;
-
-  ShadowStackGCLowering();
-
-  bool doInitialization(Module &M) override;
-  bool runOnFunction(Function &F) override;
-
-private:
-  bool IsNullValue(Value *V);
-  Constant *GetFrameMap(Function &F);
-  Type *GetConcreteStackEntryType(Function &F);
-  void CollectRoots(Function &F);
-
-  static GetElementPtrInst *CreateGEP(LLVMContext &Context, IRBuilder<> &B,
-                                      Type *Ty, Value *BasePtr, int Idx1,
-                                      const char *Name);
-  static GetElementPtrInst *CreateGEP(LLVMContext &Context, IRBuilder<> &B,
-                                      Type *Ty, Value *BasePtr, int Idx1, int Idx2,
-                                      const char *Name);
-};
-
-} // end anonymous namespace
-
-char ShadowStackGCLowering::ID = 0;
-
-INITIALIZE_PASS_BEGIN(ShadowStackGCLowering, DEBUG_TYPE,
-                      "Shadow Stack GC Lowering", false, false)
-INITIALIZE_PASS_DEPENDENCY(GCModuleInfo)
-INITIALIZE_PASS_END(ShadowStackGCLowering, DEBUG_TYPE,
-                    "Shadow Stack GC Lowering", false, false)
-
-FunctionPass *llvm::createShadowStackGCLoweringPass() { return new ShadowStackGCLowering(); }
-
-ShadowStackGCLowering::ShadowStackGCLowering() : FunctionPass(ID) {
-  initializeShadowStackGCLoweringPass(*PassRegistry::getPassRegistry());
-}
-
-Constant *ShadowStackGCLowering::GetFrameMap(Function &F) {
-  // doInitialization creates the abstract type of this value.
-  Type *VoidPtr = Type::getInt8PtrTy(F.getContext());
-
-  // Truncate the ShadowStackDescriptor if some metadata is null.
-  unsigned NumMeta = 0;
-  SmallVector<Constant *, 16> Metadata;
-  for (unsigned I = 0; I != Roots.size(); ++I) {
-    Constant *C = cast<Constant>(Roots[I].first->getArgOperand(1));
-    if (!C->isNullValue())
-      NumMeta = I + 1;
-    Metadata.push_back(ConstantExpr::getBitCast(C, VoidPtr));
-  }
-  Metadata.resize(NumMeta);
-
-  Type *Int32Ty = Type::getInt32Ty(F.getContext());
-
-  Constant *BaseElts[] = {
-      ConstantInt::get(Int32Ty, Roots.size(), false),
-      ConstantInt::get(Int32Ty, NumMeta, false),
-  };
-
-  Constant *DescriptorElts[] = {
-      ConstantStruct::get(FrameMapTy, BaseElts),
-      ConstantArray::get(ArrayType::get(VoidPtr, NumMeta), Metadata)};
-
-  Type *EltTys[] = {DescriptorElts[0]->getType(), DescriptorElts[1]->getType()};
-  StructType *STy = StructType::create(EltTys, "gc_map." + utostr(NumMeta));
-
-  Constant *FrameMap = ConstantStruct::get(STy, DescriptorElts);
-
-  // FIXME: Is this actually dangerous as WritingAnLLVMPass.html claims? Seems
-  //        that, short of multithreaded LLVM, it should be safe; all that is
-  //        necessary is that a simple Module::iterator loop not be invalidated.
-  //        Appending to the GlobalVariable list is safe in that sense.
-  //
-  //        All of the output passes emit globals last. The ExecutionEngine
-  //        explicitly supports adding globals to the module after
-  //        initialization.
-  //
-  //        Still, if it isn't deemed acceptable, then this transformation needs
-  //        to be a ModulePass (which means it cannot be in the 'llc' pipeline
-  //        (which uses a FunctionPassManager (which segfaults (not asserts) if
-  //        provided a ModulePass))).
-  Constant *GV = new GlobalVariable(*F.getParent(), FrameMap->getType(), true,
-                                    GlobalVariable::InternalLinkage, FrameMap,
-                                    "__gc_" + F.getName());
-
-  Constant *GEPIndices[2] = {
-      ConstantInt::get(Type::getInt32Ty(F.getContext()), 0),
-      ConstantInt::get(Type::getInt32Ty(F.getContext()), 0)};
-  return ConstantExpr::getGetElementPtr(FrameMap->getType(), GV, GEPIndices);
-}
-
-Type *ShadowStackGCLowering::GetConcreteStackEntryType(Function &F) {
-  // doInitialization creates the generic version of this type.
-  std::vector<Type *> EltTys;
-  EltTys.push_back(StackEntryTy);
-  for (size_t I = 0; I != Roots.size(); I++)
-    EltTys.push_back(Roots[I].second->getAllocatedType());
-
-  return StructType::create(EltTys, ("gc_stackentry." + F.getName()).str());
-}
-
-/// doInitialization - If this module uses the GC intrinsics, find them now. If
-/// not, exit fast.
-bool ShadowStackGCLowering::doInitialization(Module &M) {
-  bool Active = false;
-  for (Function &F : M) {
-    if (F.hasGC() && F.getGC() == std::string("shadow-stack")) {
-      Active = true;
-      break;
-    }
-  }
-  if (!Active)
-    return false;
-
-  // struct FrameMap {
-  //   int32_t NumRoots; // Number of roots in stack frame.
-  //   int32_t NumMeta;  // Number of metadata descriptors. May be < NumRoots.
-  //   void *Meta[];     // May be absent for roots without metadata.
-  // };
-  std::vector<Type *> EltTys;
-  // 32 bits is ok up to a 32GB stack frame. :)
-  EltTys.push_back(Type::getInt32Ty(M.getContext()));
-  // Specifies length of variable length array.
-  EltTys.push_back(Type::getInt32Ty(M.getContext()));
-  FrameMapTy = StructType::create(EltTys, "gc_map");
-  PointerType *FrameMapPtrTy = PointerType::getUnqual(FrameMapTy);
-
-  // struct StackEntry {
-  //   ShadowStackEntry *Next; // Caller's stack entry.
-  //   FrameMap *Map;          // Pointer to constant FrameMap.
-  //   void *Roots[];          // Stack roots (in-place array, so we pretend).
-  // };
-
-  StackEntryTy = StructType::create(M.getContext(), "gc_stackentry");
-
-  EltTys.clear();
-  EltTys.push_back(PointerType::getUnqual(StackEntryTy));
-  EltTys.push_back(FrameMapPtrTy);
-  StackEntryTy->setBody(EltTys);
-  PointerType *StackEntryPtrTy = PointerType::getUnqual(StackEntryTy);
-
-  // Get the root chain if it already exists.
-  Head = M.getGlobalVariable("llvm_gc_root_chain");
-  if (!Head) {
-    // If the root chain does not exist, insert a new one with linkonce
-    // linkage!
-    Head = new GlobalVariable(
-        M, StackEntryPtrTy, false, GlobalValue::LinkOnceAnyLinkage,
-        Constant::getNullValue(StackEntryPtrTy), "llvm_gc_root_chain");
-  } else if (Head->hasExternalLinkage() && Head->isDeclaration()) {
-    Head->setInitializer(Constant::getNullValue(StackEntryPtrTy));
-    Head->setLinkage(GlobalValue::LinkOnceAnyLinkage);
-  }
-
-  return true;
-}
-
-bool ShadowStackGCLowering::IsNullValue(Value *V) {
-  if (Constant *C = dyn_cast<Constant>(V))
-    return C->isNullValue();
-  return false;
-}
-
-void ShadowStackGCLowering::CollectRoots(Function &F) {
-  // FIXME: Account for original alignment. Could fragment the root array.
-  //   Approach 1: Null initialize empty slots at runtime. Yuck.
-  //   Approach 2: Emit a map of the array instead of just a count.
-
-  assert(Roots.empty() && "Not cleaned up?");
-
-  SmallVector<std::pair<CallInst *, AllocaInst *>, 16> MetaRoots;
-
-  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
-    for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E;)
-      if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(II++))
-        if (Function *F = CI->getCalledFunction())
-          if (F->getIntrinsicID() == Intrinsic::gcroot) {
-            std::pair<CallInst *, AllocaInst *> Pair = std::make_pair(
-                CI,
-                cast<AllocaInst>(CI->getArgOperand(0)->stripPointerCasts()));
-            if (IsNullValue(CI->getArgOperand(1)))
-              Roots.push_back(Pair);
-            else
-              MetaRoots.push_back(Pair);
-          }
-
-  // Number roots with metadata (usually empty) at the beginning, so that the
-  // FrameMap::Meta array can be elided.
-  Roots.insert(Roots.begin(), MetaRoots.begin(), MetaRoots.end());
-}
-
-GetElementPtrInst *ShadowStackGCLowering::CreateGEP(LLVMContext &Context,
-                                                    IRBuilder<> &B, Type *Ty,
-                                                    Value *BasePtr, int Idx,
-                                                    int Idx2,
-                                                    const char *Name) {
-  Value *Indices[] = {ConstantInt::get(Type::getInt32Ty(Context), 0),
-                      ConstantInt::get(Type::getInt32Ty(Context), Idx),
-                      ConstantInt::get(Type::getInt32Ty(Context), Idx2)};
-  Value *Val = B.CreateGEP(Ty, BasePtr, Indices, Name);
-
-  assert(isa<GetElementPtrInst>(Val) && "Unexpected folded constant");
-
-  return dyn_cast<GetElementPtrInst>(Val);
-}
-
-GetElementPtrInst *ShadowStackGCLowering::CreateGEP(LLVMContext &Context,
-                                            IRBuilder<> &B, Type *Ty, Value *BasePtr,
-                                            int Idx, const char *Name) {
-  Value *Indices[] = {ConstantInt::get(Type::getInt32Ty(Context), 0),
-                      ConstantInt::get(Type::getInt32Ty(Context), Idx)};
-  Value *Val = B.CreateGEP(Ty, BasePtr, Indices, Name);
-
-  assert(isa<GetElementPtrInst>(Val) && "Unexpected folded constant");
-
-  return dyn_cast<GetElementPtrInst>(Val);
-}
-
-/// runOnFunction - Insert code to maintain the shadow stack.
-bool ShadowStackGCLowering::runOnFunction(Function &F) {
-  // Quick exit for functions that do not use the shadow stack GC.
-  if (!F.hasGC() ||
-      F.getGC() != std::string("shadow-stack"))
-    return false;
-
-  LLVMContext &Context = F.getContext();
-
-  // Find calls to llvm.gcroot.
-  CollectRoots(F);
-
-  // If there are no roots in this function, then there is no need to add a
-  // stack map entry for it.
-  if (Roots.empty())
-    return false;
-
-  // Build the constant map and figure the type of the shadow stack entry.
-  Value *FrameMap = GetFrameMap(F);
-  Type *ConcreteStackEntryTy = GetConcreteStackEntryType(F);
-
-  // Build the shadow stack entry at the very start of the function.
-  BasicBlock::iterator IP = F.getEntryBlock().begin();
-  IRBuilder<> AtEntry(IP->getParent(), IP);
-
-  Instruction *StackEntry =
-      AtEntry.CreateAlloca(ConcreteStackEntryTy, nullptr, "gc_frame");
-
-  while (isa<AllocaInst>(IP))
-    ++IP;
-  AtEntry.SetInsertPoint(IP->getParent(), IP);
-
-  // Initialize the map pointer and load the current head of the shadow stack.
-  Instruction *CurrentHead =
-      AtEntry.CreateLoad(StackEntryTy->getPointerTo(), Head, "gc_currhead");
-  Instruction *EntryMapPtr = CreateGEP(Context, AtEntry, ConcreteStackEntryTy,
-                                       StackEntry, 0, 1, "gc_frame.map");
-  AtEntry.CreateStore(FrameMap, EntryMapPtr);
-
-  // After all the allocas...
-  for (unsigned I = 0, E = Roots.size(); I != E; ++I) {
-    // For each root, find the corresponding slot in the aggregate...
-    Value *SlotPtr = CreateGEP(Context, AtEntry, ConcreteStackEntryTy,
-                               StackEntry, 1 + I, "gc_root");
-
-    // And use it in lieu of the alloca.
-    AllocaInst *OriginalAlloca = Roots[I].second;
-    SlotPtr->takeName(OriginalAlloca);
-    OriginalAlloca->replaceAllUsesWith(SlotPtr);
-  }
-
-  // Move past the original stores inserted by GCStrategy::InitRoots. This isn't
-  // really necessary (the collector would never see the intermediate state at
-  // runtime), but it's nicer not to push the half-initialized entry onto the
-  // shadow stack.
-  while (isa<StoreInst>(IP))
-    ++IP;
-  AtEntry.SetInsertPoint(IP->getParent(), IP);
-
-  // Push the entry onto the shadow stack.
-  Instruction *EntryNextPtr = CreateGEP(Context, AtEntry, ConcreteStackEntryTy,
-                                        StackEntry, 0, 0, "gc_frame.next");
-  Instruction *NewHeadVal = CreateGEP(Context, AtEntry, ConcreteStackEntryTy,
-                                      StackEntry, 0, "gc_newhead");
-  AtEntry.CreateStore(CurrentHead, EntryNextPtr);
-  AtEntry.CreateStore(NewHeadVal, Head);
-
-  // For each instruction that escapes...
-  EscapeEnumerator EE(F, "gc_cleanup");
-  while (IRBuilder<> *AtExit = EE.Next()) {
-    // Pop the entry from the shadow stack. Don't reuse CurrentHead from
-    // AtEntry, since that would make the value live for the entire function.
-    Instruction *EntryNextPtr2 =
-        CreateGEP(Context, *AtExit, ConcreteStackEntryTy, StackEntry, 0, 0,
-                  "gc_frame.next");
-    Value *SavedHead = AtExit->CreateLoad(StackEntryTy->getPointerTo(),
-                                          EntryNextPtr2, "gc_savedhead");
-    AtExit->CreateStore(SavedHead, Head);
-  }
-
-  // Delete the original allocas (which are no longer used) and the intrinsic
-  // calls (which are no longer valid). Doing this last avoids invalidating
-  // iterators.
-  for (unsigned I = 0, E = Roots.size(); I != E; ++I) {
-    Roots[I].first->eraseFromParent();
-    Roots[I].second->eraseFromParent();
-  }
-
-  Roots.clear();
-  return true;
-}