LCOV - code coverage report
Current view: top level - lib/CodeGen - SafeStack.cpp (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 155 284 54.6 %
Date: 2018-10-20 13:21:21 Functions: 14 21 66.7 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- SafeStack.cpp - Safe Stack Insertion -------------------------------===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : // This pass splits the stack into the safe stack (kept as-is for LLVM backend)
      11             : // and the unsafe stack (explicitly allocated and managed through the runtime
      12             : // support library).
      13             : //
      14             : // http://clang.llvm.org/docs/SafeStack.html
      15             : //
      16             : //===----------------------------------------------------------------------===//
      17             : 
      18             : #include "SafeStackColoring.h"
      19             : #include "SafeStackLayout.h"
      20             : #include "llvm/ADT/APInt.h"
      21             : #include "llvm/ADT/ArrayRef.h"
      22             : #include "llvm/ADT/SmallPtrSet.h"
      23             : #include "llvm/ADT/SmallVector.h"
      24             : #include "llvm/ADT/Statistic.h"
      25             : #include "llvm/Analysis/AssumptionCache.h"
      26             : #include "llvm/Analysis/BranchProbabilityInfo.h"
      27             : #include "llvm/Analysis/InlineCost.h"
      28             : #include "llvm/Analysis/LoopInfo.h"
      29             : #include "llvm/Analysis/ScalarEvolution.h"
      30             : #include "llvm/Analysis/ScalarEvolutionExpressions.h"
      31             : #include "llvm/Analysis/TargetLibraryInfo.h"
      32             : #include "llvm/Transforms/Utils/Local.h"
      33             : #include "llvm/CodeGen/TargetLowering.h"
      34             : #include "llvm/CodeGen/TargetPassConfig.h"
      35             : #include "llvm/CodeGen/TargetSubtargetInfo.h"
      36             : #include "llvm/IR/Argument.h"
      37             : #include "llvm/IR/Attributes.h"
      38             : #include "llvm/IR/CallSite.h"
      39             : #include "llvm/IR/ConstantRange.h"
      40             : #include "llvm/IR/Constants.h"
      41             : #include "llvm/IR/DIBuilder.h"
      42             : #include "llvm/IR/DataLayout.h"
      43             : #include "llvm/IR/DerivedTypes.h"
      44             : #include "llvm/IR/Dominators.h"
      45             : #include "llvm/IR/Function.h"
      46             : #include "llvm/IR/IRBuilder.h"
      47             : #include "llvm/IR/InstIterator.h"
      48             : #include "llvm/IR/Instruction.h"
      49             : #include "llvm/IR/Instructions.h"
      50             : #include "llvm/IR/IntrinsicInst.h"
      51             : #include "llvm/IR/Intrinsics.h"
      52             : #include "llvm/IR/MDBuilder.h"
      53             : #include "llvm/IR/Module.h"
      54             : #include "llvm/IR/Type.h"
      55             : #include "llvm/IR/Use.h"
      56             : #include "llvm/IR/User.h"
      57             : #include "llvm/IR/Value.h"
      58             : #include "llvm/Pass.h"
      59             : #include "llvm/Support/Casting.h"
      60             : #include "llvm/Support/Debug.h"
      61             : #include "llvm/Support/ErrorHandling.h"
      62             : #include "llvm/Support/MathExtras.h"
      63             : #include "llvm/Support/raw_ostream.h"
      64             : #include "llvm/Target/TargetMachine.h"
      65             : #include "llvm/Transforms/Utils/BasicBlockUtils.h"
      66             : #include "llvm/Transforms/Utils/Cloning.h"
      67             : #include <algorithm>
      68             : #include <cassert>
      69             : #include <cstdint>
      70             : #include <string>
      71             : #include <utility>
      72             : 
      73             : using namespace llvm;
      74             : using namespace llvm::safestack;
      75             : 
      76             : #define DEBUG_TYPE "safe-stack"
      77             : 
      78             : namespace llvm {
      79             : 
      80             : STATISTIC(NumFunctions, "Total number of functions");
      81             : STATISTIC(NumUnsafeStackFunctions, "Number of functions with unsafe stack");
      82             : STATISTIC(NumUnsafeStackRestorePointsFunctions,
      83             :           "Number of functions that use setjmp or exceptions");
      84             : 
      85             : STATISTIC(NumAllocas, "Total number of allocas");
      86             : STATISTIC(NumUnsafeStaticAllocas, "Number of unsafe static allocas");
      87             : STATISTIC(NumUnsafeDynamicAllocas, "Number of unsafe dynamic allocas");
      88             : STATISTIC(NumUnsafeByValArguments, "Number of unsafe byval arguments");
      89             : STATISTIC(NumUnsafeStackRestorePoints, "Number of setjmps and landingpads");
      90             : 
      91             : } // namespace llvm
      92             : 
      93             : /// Use __safestack_pointer_address even if the platform has a faster way of
      94             : /// access safe stack pointer.
      95             : static cl::opt<bool>
      96             :     SafeStackUsePointerAddress("safestack-use-pointer-address",
      97             :                                   cl::init(false), cl::Hidden);
      98             : 
      99             : 
     100             : namespace {
     101             : 
     102             : /// Rewrite an SCEV expression for a memory access address to an expression that
     103             : /// represents offset from the given alloca.
     104             : ///
     105             : /// The implementation simply replaces all mentions of the alloca with zero.
     106             : class AllocaOffsetRewriter : public SCEVRewriteVisitor<AllocaOffsetRewriter> {
     107             :   const Value *AllocaPtr;
     108             : 
     109             : public:
     110             :   AllocaOffsetRewriter(ScalarEvolution &SE, const Value *AllocaPtr)
     111           0 :       : SCEVRewriteVisitor(SE), AllocaPtr(AllocaPtr) {}
     112             : 
     113           0 :   const SCEV *visitUnknown(const SCEVUnknown *Expr) {
     114         122 :     if (Expr->getValue() == AllocaPtr)
     115           0 :       return SE.getZero(Expr->getType());
     116          11 :     return Expr;
     117             :   }
     118             : };
     119             : 
     120             : /// The SafeStack pass splits the stack of each function into the safe
     121             : /// stack, which is only accessed through memory safe dereferences (as
     122             : /// determined statically), and the unsafe stack, which contains all
     123             : /// local variables that are accessed in ways that we can't prove to
     124             : /// be safe.
     125             : class SafeStack {
     126             :   Function &F;
     127             :   const TargetLoweringBase &TL;
     128             :   const DataLayout &DL;
     129             :   ScalarEvolution &SE;
     130             : 
     131             :   Type *StackPtrTy;
     132             :   Type *IntPtrTy;
     133             :   Type *Int32Ty;
     134             :   Type *Int8Ty;
     135             : 
     136             :   Value *UnsafeStackPtr = nullptr;
     137             : 
     138             :   /// Unsafe stack alignment. Each stack frame must ensure that the stack is
     139             :   /// aligned to this value. We need to re-align the unsafe stack if the
     140             :   /// alignment of any object on the stack exceeds this value.
     141             :   ///
     142             :   /// 16 seems like a reasonable upper bound on the alignment of objects that we
     143             :   /// might expect to appear on the stack on most common targets.
     144             :   enum { StackAlignment = 16 };
     145             : 
     146             :   /// Return the value of the stack canary.
     147             :   Value *getStackGuard(IRBuilder<> &IRB, Function &F);
     148             : 
     149             :   /// Load stack guard from the frame and check if it has changed.
     150             :   void checkStackGuard(IRBuilder<> &IRB, Function &F, ReturnInst &RI,
     151             :                        AllocaInst *StackGuardSlot, Value *StackGuard);
     152             : 
     153             :   /// Find all static allocas, dynamic allocas, return instructions and
     154             :   /// stack restore points (exception unwind blocks and setjmp calls) in the
     155             :   /// given function and append them to the respective vectors.
     156             :   void findInsts(Function &F, SmallVectorImpl<AllocaInst *> &StaticAllocas,
     157             :                  SmallVectorImpl<AllocaInst *> &DynamicAllocas,
     158             :                  SmallVectorImpl<Argument *> &ByValArguments,
     159             :                  SmallVectorImpl<ReturnInst *> &Returns,
     160             :                  SmallVectorImpl<Instruction *> &StackRestorePoints);
     161             : 
     162             :   /// Calculate the allocation size of a given alloca. Returns 0 if the
     163             :   /// size can not be statically determined.
     164             :   uint64_t getStaticAllocaAllocationSize(const AllocaInst* AI);
     165             : 
     166             :   /// Allocate space for all static allocas in \p StaticAllocas,
     167             :   /// replace allocas with pointers into the unsafe stack and generate code to
     168             :   /// restore the stack pointer before all return instructions in \p Returns.
     169             :   ///
     170             :   /// \returns A pointer to the top of the unsafe stack after all unsafe static
     171             :   /// allocas are allocated.
     172             :   Value *moveStaticAllocasToUnsafeStack(IRBuilder<> &IRB, Function &F,
     173             :                                         ArrayRef<AllocaInst *> StaticAllocas,
     174             :                                         ArrayRef<Argument *> ByValArguments,
     175             :                                         ArrayRef<ReturnInst *> Returns,
     176             :                                         Instruction *BasePointer,
     177             :                                         AllocaInst *StackGuardSlot);
     178             : 
     179             :   /// Generate code to restore the stack after all stack restore points
     180             :   /// in \p StackRestorePoints.
     181             :   ///
     182             :   /// \returns A local variable in which to maintain the dynamic top of the
     183             :   /// unsafe stack if needed.
     184             :   AllocaInst *
     185             :   createStackRestorePoints(IRBuilder<> &IRB, Function &F,
     186             :                            ArrayRef<Instruction *> StackRestorePoints,
     187             :                            Value *StaticTop, bool NeedDynamicTop);
     188             : 
     189             :   /// Replace all allocas in \p DynamicAllocas with code to allocate
     190             :   /// space dynamically on the unsafe stack and store the dynamic unsafe stack
     191             :   /// top to \p DynamicTop if non-null.
     192             :   void moveDynamicAllocasToUnsafeStack(Function &F, Value *UnsafeStackPtr,
     193             :                                        AllocaInst *DynamicTop,
     194             :                                        ArrayRef<AllocaInst *> DynamicAllocas);
     195             : 
     196             :   bool IsSafeStackAlloca(const Value *AllocaPtr, uint64_t AllocaSize);
     197             : 
     198             :   bool IsMemIntrinsicSafe(const MemIntrinsic *MI, const Use &U,
     199             :                           const Value *AllocaPtr, uint64_t AllocaSize);
     200             :   bool IsAccessSafe(Value *Addr, uint64_t Size, const Value *AllocaPtr,
     201             :                     uint64_t AllocaSize);
     202             : 
     203             :   bool ShouldInlinePointerAddress(CallSite &CS);
     204             :   void TryInlinePointerAddress();
     205             : 
     206             : public:
     207         190 :   SafeStack(Function &F, const TargetLoweringBase &TL, const DataLayout &DL,
     208             :             ScalarEvolution &SE)
     209         190 :       : F(F), TL(TL), DL(DL), SE(SE),
     210         190 :         StackPtrTy(Type::getInt8PtrTy(F.getContext())),
     211         190 :         IntPtrTy(DL.getIntPtrType(F.getContext())),
     212         190 :         Int32Ty(Type::getInt32Ty(F.getContext())),
     213         760 :         Int8Ty(Type::getInt8Ty(F.getContext())) {}
     214             : 
     215             :   // Run the transformation on the associated function.
     216             :   // Returns whether the function was changed.
     217             :   bool run();
     218             : };
     219             : 
     220           0 : uint64_t SafeStack::getStaticAllocaAllocationSize(const AllocaInst* AI) {
     221           0 :   uint64_t Size = DL.getTypeAllocSize(AI->getAllocatedType());
     222           0 :   if (AI->isArrayAllocation()) {
     223             :     auto C = dyn_cast<ConstantInt>(AI->getArraySize());
     224             :     if (!C)
     225           0 :       return 0;
     226           0 :     Size *= C->getZExtValue();
     227             :   }
     228             :   return Size;
     229             : }
     230             : 
     231           0 : bool SafeStack::IsAccessSafe(Value *Addr, uint64_t AccessSize,
     232             :                              const Value *AllocaPtr, uint64_t AllocaSize) {
     233           0 :   AllocaOffsetRewriter Rewriter(SE, AllocaPtr);
     234           0 :   const SCEV *Expr = Rewriter.visit(SE.getSCEV(Addr));
     235             : 
     236           0 :   uint64_t BitWidth = SE.getTypeSizeInBits(Expr->getType());
     237           0 :   ConstantRange AccessStartRange = SE.getUnsignedRange(Expr);
     238             :   ConstantRange SizeRange =
     239           0 :       ConstantRange(APInt(BitWidth, 0), APInt(BitWidth, AccessSize));
     240           0 :   ConstantRange AccessRange = AccessStartRange.add(SizeRange);
     241             :   ConstantRange AllocaRange =
     242           0 :       ConstantRange(APInt(BitWidth, 0), APInt(BitWidth, AllocaSize));
     243           0 :   bool Safe = AllocaRange.contains(AccessRange);
     244             : 
     245             :   LLVM_DEBUG(
     246             :       dbgs() << "[SafeStack] "
     247             :              << (isa<AllocaInst>(AllocaPtr) ? "Alloca " : "ByValArgument ")
     248             :              << *AllocaPtr << "\n"
     249             :              << "            Access " << *Addr << "\n"
     250             :              << "            SCEV " << *Expr
     251             :              << " U: " << SE.getUnsignedRange(Expr)
     252             :              << ", S: " << SE.getSignedRange(Expr) << "\n"
     253             :              << "            Range " << AccessRange << "\n"
     254             :              << "            AllocaRange " << AllocaRange << "\n"
     255             :              << "            " << (Safe ? "safe" : "unsafe") << "\n");
     256             : 
     257           0 :   return Safe;
     258             : }
     259             : 
     260          11 : bool SafeStack::IsMemIntrinsicSafe(const MemIntrinsic *MI, const Use &U,
     261             :                                    const Value *AllocaPtr,
     262             :                                    uint64_t AllocaSize) {
     263             :   if (auto MTI = dyn_cast<MemTransferInst>(MI)) {
     264           3 :     if (MTI->getRawSource() != U && MTI->getRawDest() != U)
     265             :       return true;
     266             :   } else {
     267           8 :     if (MI->getRawDest() != U)
     268             :       return true;
     269             :   }
     270             : 
     271             :   const auto *Len = dyn_cast<ConstantInt>(MI->getLength());
     272             :   // Non-constant size => unsafe. FIXME: try SCEV getRange.
     273             :   if (!Len) return false;
     274           9 :   return IsAccessSafe(U, Len->getZExtValue(), AllocaPtr, AllocaSize);
     275             : }
     276             : 
     277             : /// Check whether a given allocation must be put on the safe
     278             : /// stack or not. The function analyzes all uses of AI and checks whether it is
     279             : /// only accessed in a memory safe way (as decided statically).
     280         315 : bool SafeStack::IsSafeStackAlloca(const Value *AllocaPtr, uint64_t AllocaSize) {
     281             :   // Go through all uses of this alloca and check whether all accesses to the
     282             :   // allocated object are statically known to be memory safe and, hence, the
     283             :   // object can be placed on the safe stack.
     284             :   SmallPtrSet<const Value *, 16> Visited;
     285             :   SmallVector<const Value *, 8> WorkList;
     286         315 :   WorkList.push_back(AllocaPtr);
     287             : 
     288             :   // A DFS search through all uses of the alloca in bitcasts/PHI/GEPs/etc.
     289         522 :   while (!WorkList.empty()) {
     290             :     const Value *V = WorkList.pop_back_val();
     291         699 :     for (const Use &UI : V->uses()) {
     292         492 :       auto I = cast<const Instruction>(UI.getUser());
     293             :       assert(V == UI.get());
     294             : 
     295         492 :       switch (I->getOpcode()) {
     296          53 :       case Instruction::Load:
     297          53 :         if (!IsAccessSafe(UI, DL.getTypeStoreSize(I->getType()), AllocaPtr,
     298             :                           AllocaSize))
     299             :           return false;
     300             :         break;
     301             : 
     302             :       case Instruction::VAArg:
     303             :         // "va-arg" from a pointer is safe.
     304             :         break;
     305          63 :       case Instruction::Store:
     306         126 :         if (V == I->getOperand(0)) {
     307             :           // Stored the pointer - conservatively assume it may be unsafe.
     308             :           LLVM_DEBUG(dbgs()
     309             :                      << "[SafeStack] Unsafe alloca: " << *AllocaPtr
     310             :                      << "\n            store of address: " << *I << "\n");
     311             :           return false;
     312             :         }
     313             : 
     314         102 :         if (!IsAccessSafe(UI, DL.getTypeStoreSize(I->getOperand(0)->getType()),
     315             :                           AllocaPtr, AllocaSize))
     316             :           return false;
     317             :         break;
     318             : 
     319             :       case Instruction::Ret:
     320             :         // Information leak.
     321             :         return false;
     322             : 
     323             :       case Instruction::Call:
     324             :       case Instruction::Invoke: {
     325             :         ImmutableCallSite CS(I);
     326             : 
     327             :         if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
     328          21 :           if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
     329             :               II->getIntrinsicID() == Intrinsic::lifetime_end)
     330          17 :             continue;
     331             :         }
     332             : 
     333             :         if (const MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I)) {
     334          11 :           if (!IsMemIntrinsicSafe(MI, UI, AllocaPtr, AllocaSize)) {
     335             :             LLVM_DEBUG(dbgs()
     336             :                        << "[SafeStack] Unsafe alloca: " << *AllocaPtr
     337             :                        << "\n            unsafe memintrinsic: " << *I << "\n");
     338         211 :             return false;
     339             :           }
     340             :           continue;
     341             :         }
     342             : 
     343             :         // LLVM 'nocapture' attribute is only set for arguments whose address
     344             :         // is not stored, passed around, or used in any other non-trivial way.
     345             :         // We assume that passing a pointer to an object as a 'nocapture
     346             :         // readnone' argument is safe.
     347             :         // FIXME: a more precise solution would require an interprocedural
     348             :         // analysis here, which would look at all uses of an argument inside
     349             :         // the function being called.
     350         207 :         ImmutableCallSite::arg_iterator B = CS.arg_begin(), E = CS.arg_end();
     351         227 :         for (ImmutableCallSite::arg_iterator A = B; A != E; ++A)
     352         223 :           if (A->get() == V)
     353         229 :             if (!(CS.doesNotCapture(A - B) && (CS.doesNotAccessMemory(A - B) ||
     354          10 :                                                CS.doesNotAccessMemory()))) {
     355             :               LLVM_DEBUG(dbgs() << "[SafeStack] Unsafe alloca: " << *AllocaPtr
     356             :                                 << "\n            unsafe call: " << *I << "\n");
     357         203 :               return false;
     358             :             }
     359             :         continue;
     360             :       }
     361             : 
     362         146 :       default:
     363         146 :         if (Visited.insert(I).second)
     364         144 :           WorkList.push_back(cast<const Instruction>(I));
     365             :       }
     366             :     }
     367             :   }
     368             : 
     369             :   // All uses of the alloca are safe, we can place it on the safe stack.
     370             :   return true;
     371             : }
     372             : 
     373           0 : Value *SafeStack::getStackGuard(IRBuilder<> &IRB, Function &F) {
     374           0 :   Value *StackGuardVar = TL.getIRStackGuard(IRB);
     375           0 :   if (!StackGuardVar)
     376             :     StackGuardVar =
     377           0 :         F.getParent()->getOrInsertGlobal("__stack_chk_guard", StackPtrTy);
     378           0 :   return IRB.CreateLoad(StackGuardVar, "StackGuard");
     379             : }
     380             : 
     381         190 : void SafeStack::findInsts(Function &F,
     382             :                           SmallVectorImpl<AllocaInst *> &StaticAllocas,
     383             :                           SmallVectorImpl<AllocaInst *> &DynamicAllocas,
     384             :                           SmallVectorImpl<Argument *> &ByValArguments,
     385             :                           SmallVectorImpl<ReturnInst *> &Returns,
     386             :                           SmallVectorImpl<Instruction *> &StackRestorePoints) {
     387        1418 :   for (Instruction &I : instructions(&F)) {
     388        1418 :     if (auto AI = dyn_cast<AllocaInst>(&I)) {
     389             :       ++NumAllocas;
     390             : 
     391         305 :       uint64_t Size = getStaticAllocaAllocationSize(AI);
     392         305 :       if (IsSafeStackAlloca(AI, Size))
     393          64 :         continue;
     394             : 
     395         241 :       if (AI->isStaticAlloca()) {
     396             :         ++NumUnsafeStaticAllocas;
     397         232 :         StaticAllocas.push_back(AI);
     398             :       } else {
     399             :         ++NumUnsafeDynamicAllocas;
     400           9 :         DynamicAllocas.push_back(AI);
     401             :       }
     402        1113 :     } else if (auto RI = dyn_cast<ReturnInst>(&I)) {
     403         200 :       Returns.push_back(RI);
     404             :     } else if (auto CI = dyn_cast<CallInst>(&I)) {
     405             :       // setjmps require stack restore.
     406         441 :       if (CI->getCalledFunction() && CI->canReturnTwice())
     407           5 :         StackRestorePoints.push_back(CI);
     408             :     } else if (auto LP = dyn_cast<LandingPadInst>(&I)) {
     409             :       // Exception landing pads require stack restore.
     410           4 :       StackRestorePoints.push_back(LP);
     411             :     } else if (auto II = dyn_cast<IntrinsicInst>(&I)) {
     412           0 :       if (II->getIntrinsicID() == Intrinsic::gcroot)
     413           0 :         report_fatal_error(
     414             :             "gcroot intrinsic not compatible with safestack attribute");
     415             :     }
     416             :   }
     417         270 :   for (Argument &Arg : F.args()) {
     418          80 :     if (!Arg.hasByValAttr())
     419             :       continue;
     420             :     uint64_t Size =
     421          10 :         DL.getTypeStoreSize(Arg.getType()->getPointerElementType());
     422          10 :     if (IsSafeStackAlloca(&Arg, Size))
     423             :       continue;
     424             : 
     425             :     ++NumUnsafeByValArguments;
     426           7 :     ByValArguments.push_back(&Arg);
     427             :   }
     428         190 : }
     429             : 
     430             : AllocaInst *
     431         161 : SafeStack::createStackRestorePoints(IRBuilder<> &IRB, Function &F,
     432             :                                     ArrayRef<Instruction *> StackRestorePoints,
     433             :                                     Value *StaticTop, bool NeedDynamicTop) {
     434             :   assert(StaticTop && "The stack top isn't set.");
     435             : 
     436         161 :   if (StackRestorePoints.empty())
     437             :     return nullptr;
     438             : 
     439             :   // We need the current value of the shadow stack pointer to restore
     440             :   // after longjmp or exception catching.
     441             : 
     442             :   // FIXME: On some platforms this could be handled by the longjmp/exception
     443             :   // runtime itself.
     444             : 
     445             :   AllocaInst *DynamicTop = nullptr;
     446           9 :   if (NeedDynamicTop) {
     447             :     // If we also have dynamic alloca's, the stack pointer value changes
     448             :     // throughout the function. For now we store it in an alloca.
     449           3 :     DynamicTop = IRB.CreateAlloca(StackPtrTy, /*ArraySize=*/nullptr,
     450             :                                   "unsafe_stack_dynamic_ptr");
     451           3 :     IRB.CreateStore(StaticTop, DynamicTop);
     452             :   }
     453             : 
     454             :   // Restore current stack pointer after longjmp/exception catch.
     455          18 :   for (Instruction *I : StackRestorePoints) {
     456             :     ++NumUnsafeStackRestorePoints;
     457             : 
     458          18 :     IRB.SetInsertPoint(I->getNextNode());
     459           9 :     Value *CurrentTop = DynamicTop ? IRB.CreateLoad(DynamicTop) : StaticTop;
     460           9 :     IRB.CreateStore(CurrentTop, UnsafeStackPtr);
     461             :   }
     462             : 
     463             :   return DynamicTop;
     464             : }
     465             : 
     466           0 : void SafeStack::checkStackGuard(IRBuilder<> &IRB, Function &F, ReturnInst &RI,
     467             :                                 AllocaInst *StackGuardSlot, Value *StackGuard) {
     468           0 :   Value *V = IRB.CreateLoad(StackGuardSlot);
     469           0 :   Value *Cmp = IRB.CreateICmpNE(StackGuard, V);
     470             : 
     471           0 :   auto SuccessProb = BranchProbabilityInfo::getBranchProbStackProtector(true);
     472           0 :   auto FailureProb = BranchProbabilityInfo::getBranchProbStackProtector(false);
     473           0 :   MDNode *Weights = MDBuilder(F.getContext())
     474           0 :                         .createBranchWeights(SuccessProb.getNumerator(),
     475             :                                              FailureProb.getNumerator());
     476             :   Instruction *CheckTerm =
     477           0 :       SplitBlockAndInsertIfThen(Cmp, &RI,
     478             :                                 /* Unreachable */ true, Weights);
     479           0 :   IRBuilder<> IRBFail(CheckTerm);
     480             :   // FIXME: respect -fsanitize-trap / -ftrap-function here?
     481           0 :   Constant *StackChkFail = F.getParent()->getOrInsertFunction(
     482             :       "__stack_chk_fail", IRB.getVoidTy());
     483           0 :   IRBFail.CreateCall(StackChkFail, {});
     484           0 : }
     485             : 
     486             : /// We explicitly compute and set the unsafe stack layout for all unsafe
     487             : /// static alloca instructions. We save the unsafe "base pointer" in the
     488             : /// prologue into a local variable and restore it in the epilogue.
     489           0 : Value *SafeStack::moveStaticAllocasToUnsafeStack(
     490             :     IRBuilder<> &IRB, Function &F, ArrayRef<AllocaInst *> StaticAllocas,
     491             :     ArrayRef<Argument *> ByValArguments, ArrayRef<ReturnInst *> Returns,
     492             :     Instruction *BasePointer, AllocaInst *StackGuardSlot) {
     493           0 :   if (StaticAllocas.empty() && ByValArguments.empty())
     494           0 :     return BasePointer;
     495             : 
     496           0 :   DIBuilder DIB(*F.getParent());
     497             : 
     498           0 :   StackColoring SSC(F, StaticAllocas);
     499           0 :   SSC.run();
     500           0 :   SSC.removeAllMarkers();
     501             : 
     502             :   // Unsafe stack always grows down.
     503           0 :   StackLayout SSL(StackAlignment);
     504           0 :   if (StackGuardSlot) {
     505           0 :     Type *Ty = StackGuardSlot->getAllocatedType();
     506             :     unsigned Align =
     507           0 :         std::max(DL.getPrefTypeAlignment(Ty), StackGuardSlot->getAlignment());
     508           0 :     SSL.addObject(StackGuardSlot, getStaticAllocaAllocationSize(StackGuardSlot),
     509           0 :                   Align, SSC.getFullLiveRange());
     510             :   }
     511             : 
     512           0 :   for (Argument *Arg : ByValArguments) {
     513           0 :     Type *Ty = Arg->getType()->getPointerElementType();
     514           0 :     uint64_t Size = DL.getTypeStoreSize(Ty);
     515           0 :     if (Size == 0)
     516             :       Size = 1; // Don't create zero-sized stack objects.
     517             : 
     518             :     // Ensure the object is properly aligned.
     519           0 :     unsigned Align = std::max((unsigned)DL.getPrefTypeAlignment(Ty),
     520           0 :                               Arg->getParamAlignment());
     521           0 :     SSL.addObject(Arg, Size, Align, SSC.getFullLiveRange());
     522             :   }
     523             : 
     524           0 :   for (AllocaInst *AI : StaticAllocas) {
     525           0 :     Type *Ty = AI->getAllocatedType();
     526           0 :     uint64_t Size = getStaticAllocaAllocationSize(AI);
     527           0 :     if (Size == 0)
     528             :       Size = 1; // Don't create zero-sized stack objects.
     529             : 
     530             :     // Ensure the object is properly aligned.
     531             :     unsigned Align =
     532           0 :         std::max((unsigned)DL.getPrefTypeAlignment(Ty), AI->getAlignment());
     533             : 
     534           0 :     SSL.addObject(AI, Size, Align, SSC.getLiveRange(AI));
     535             :   }
     536             : 
     537           0 :   SSL.computeLayout();
     538           0 :   unsigned FrameAlignment = SSL.getFrameAlignment();
     539             : 
     540             :   // FIXME: tell SSL that we start at a less-then-MaxAlignment aligned location
     541             :   // (AlignmentSkew).
     542           0 :   if (FrameAlignment > StackAlignment) {
     543             :     // Re-align the base pointer according to the max requested alignment.
     544             :     assert(isPowerOf2_32(FrameAlignment));
     545           0 :     IRB.SetInsertPoint(BasePointer->getNextNode());
     546           0 :     BasePointer = cast<Instruction>(IRB.CreateIntToPtr(
     547             :         IRB.CreateAnd(IRB.CreatePtrToInt(BasePointer, IntPtrTy),
     548           0 :                       ConstantInt::get(IntPtrTy, ~uint64_t(FrameAlignment - 1))),
     549             :         StackPtrTy));
     550             :   }
     551             : 
     552           0 :   IRB.SetInsertPoint(BasePointer->getNextNode());
     553             : 
     554           0 :   if (StackGuardSlot) {
     555           0 :     unsigned Offset = SSL.getObjectOffset(StackGuardSlot);
     556           0 :     Value *Off = IRB.CreateGEP(BasePointer, // BasePointer is i8*
     557           0 :                                ConstantInt::get(Int32Ty, -Offset));
     558             :     Value *NewAI =
     559           0 :         IRB.CreateBitCast(Off, StackGuardSlot->getType(), "StackGuardSlot");
     560             : 
     561             :     // Replace alloc with the new location.
     562           0 :     StackGuardSlot->replaceAllUsesWith(NewAI);
     563           0 :     StackGuardSlot->eraseFromParent();
     564             :   }
     565             : 
     566           0 :   for (Argument *Arg : ByValArguments) {
     567           0 :     unsigned Offset = SSL.getObjectOffset(Arg);
     568           0 :     unsigned Align = SSL.getObjectAlignment(Arg);
     569           0 :     Type *Ty = Arg->getType()->getPointerElementType();
     570             : 
     571           0 :     uint64_t Size = DL.getTypeStoreSize(Ty);
     572           0 :     if (Size == 0)
     573             :       Size = 1; // Don't create zero-sized stack objects.
     574             : 
     575           0 :     Value *Off = IRB.CreateGEP(BasePointer, // BasePointer is i8*
     576           0 :                                ConstantInt::get(Int32Ty, -Offset));
     577           0 :     Value *NewArg = IRB.CreateBitCast(Off, Arg->getType(),
     578           0 :                                      Arg->getName() + ".unsafe-byval");
     579             : 
     580             :     // Replace alloc with the new location.
     581           0 :     replaceDbgDeclare(Arg, BasePointer, BasePointer->getNextNode(), DIB,
     582             :                       DIExpression::NoDeref, -Offset, DIExpression::NoDeref);
     583           0 :     Arg->replaceAllUsesWith(NewArg);
     584           0 :     IRB.SetInsertPoint(cast<Instruction>(NewArg)->getNextNode());
     585           0 :     IRB.CreateMemCpy(Off, Align, Arg, Arg->getParamAlignment(), Size);
     586             :   }
     587             : 
     588             :   // Allocate space for every unsafe static AllocaInst on the unsafe stack.
     589           0 :   for (AllocaInst *AI : StaticAllocas) {
     590           0 :     IRB.SetInsertPoint(AI);
     591           0 :     unsigned Offset = SSL.getObjectOffset(AI);
     592             : 
     593           0 :     uint64_t Size = getStaticAllocaAllocationSize(AI);
     594             :     if (Size == 0)
     595             :       Size = 1; // Don't create zero-sized stack objects.
     596             : 
     597           0 :     replaceDbgDeclareForAlloca(AI, BasePointer, DIB, DIExpression::NoDeref,
     598           0 :                                -Offset, DIExpression::NoDeref);
     599           0 :     replaceDbgValueForAlloca(AI, BasePointer, DIB, -Offset);
     600             : 
     601             :     // Replace uses of the alloca with the new location.
     602             :     // Insert address calculation close to each use to work around PR27844.
     603           0 :     std::string Name = std::string(AI->getName()) + ".unsafe";
     604           0 :     while (!AI->use_empty()) {
     605             :       Use &U = *AI->use_begin();
     606           0 :       Instruction *User = cast<Instruction>(U.getUser());
     607             : 
     608             :       Instruction *InsertBefore;
     609             :       if (auto *PHI = dyn_cast<PHINode>(User))
     610             :         InsertBefore = PHI->getIncomingBlock(U)->getTerminator();
     611             :       else
     612             :         InsertBefore = User;
     613             : 
     614           0 :       IRBuilder<> IRBUser(InsertBefore);
     615           0 :       Value *Off = IRBUser.CreateGEP(BasePointer, // BasePointer is i8*
     616           0 :                                      ConstantInt::get(Int32Ty, -Offset));
     617           0 :       Value *Replacement = IRBUser.CreateBitCast(Off, AI->getType(), Name);
     618             : 
     619             :       if (auto *PHI = dyn_cast<PHINode>(User)) {
     620             :         // PHI nodes may have multiple incoming edges from the same BB (why??),
     621             :         // all must be updated at once with the same incoming value.
     622             :         auto *BB = PHI->getIncomingBlock(U);
     623           0 :         for (unsigned I = 0; I < PHI->getNumIncomingValues(); ++I)
     624           0 :           if (PHI->getIncomingBlock(I) == BB)
     625             :             PHI->setIncomingValue(I, Replacement);
     626             :       } else {
     627           0 :         U.set(Replacement);
     628             :       }
     629             :     }
     630             : 
     631           0 :     AI->eraseFromParent();
     632             :   }
     633             : 
     634             :   // Re-align BasePointer so that our callees would see it aligned as
     635             :   // expected.
     636             :   // FIXME: no need to update BasePointer in leaf functions.
     637           0 :   unsigned FrameSize = alignTo(SSL.getFrameSize(), StackAlignment);
     638             : 
     639             :   // Update shadow stack pointer in the function epilogue.
     640           0 :   IRB.SetInsertPoint(BasePointer->getNextNode());
     641             : 
     642             :   Value *StaticTop =
     643           0 :       IRB.CreateGEP(BasePointer, ConstantInt::get(Int32Ty, -FrameSize),
     644             :                     "unsafe_stack_static_top");
     645           0 :   IRB.CreateStore(StaticTop, UnsafeStackPtr);
     646             :   return StaticTop;
     647             : }
     648             : 
     649         161 : void SafeStack::moveDynamicAllocasToUnsafeStack(
     650             :     Function &F, Value *UnsafeStackPtr, AllocaInst *DynamicTop,
     651             :     ArrayRef<AllocaInst *> DynamicAllocas) {
     652         322 :   DIBuilder DIB(*F.getParent());
     653             : 
     654         170 :   for (AllocaInst *AI : DynamicAllocas) {
     655           9 :     IRBuilder<> IRB(AI);
     656             : 
     657             :     // Compute the new SP value (after AI).
     658             :     Value *ArraySize = AI->getArraySize();
     659           9 :     if (ArraySize->getType() != IntPtrTy)
     660           6 :       ArraySize = IRB.CreateIntCast(ArraySize, IntPtrTy, false);
     661             : 
     662           9 :     Type *Ty = AI->getAllocatedType();
     663           9 :     uint64_t TySize = DL.getTypeAllocSize(Ty);
     664           9 :     Value *Size = IRB.CreateMul(ArraySize, ConstantInt::get(IntPtrTy, TySize));
     665             : 
     666          27 :     Value *SP = IRB.CreatePtrToInt(IRB.CreateLoad(UnsafeStackPtr), IntPtrTy);
     667           9 :     SP = IRB.CreateSub(SP, Size);
     668             : 
     669             :     // Align the SP value to satisfy the AllocaInst, type and stack alignments.
     670             :     unsigned Align = std::max(
     671           9 :         std::max((unsigned)DL.getPrefTypeAlignment(Ty), AI->getAlignment()),
     672          18 :         (unsigned)StackAlignment);
     673             : 
     674             :     assert(isPowerOf2_32(Align));
     675           9 :     Value *NewTop = IRB.CreateIntToPtr(
     676           9 :         IRB.CreateAnd(SP, ConstantInt::get(IntPtrTy, ~uint64_t(Align - 1))),
     677             :         StackPtrTy);
     678             : 
     679             :     // Save the stack pointer.
     680           9 :     IRB.CreateStore(NewTop, UnsafeStackPtr);
     681           9 :     if (DynamicTop)
     682           3 :       IRB.CreateStore(NewTop, DynamicTop);
     683             : 
     684           9 :     Value *NewAI = IRB.CreatePointerCast(NewTop, AI->getType());
     685           9 :     if (AI->hasName() && isa<Instruction>(NewAI))
     686           6 :       NewAI->takeName(AI);
     687             : 
     688           9 :     replaceDbgDeclareForAlloca(AI, NewAI, DIB, DIExpression::NoDeref, 0,
     689             :                                DIExpression::NoDeref);
     690           9 :     AI->replaceAllUsesWith(NewAI);
     691           9 :     AI->eraseFromParent();
     692             :   }
     693             : 
     694         161 :   if (!DynamicAllocas.empty()) {
     695             :     // Now go through the instructions again, replacing stacksave/stackrestore.
     696             :     for (inst_iterator It = inst_begin(&F), Ie = inst_end(&F); It != Ie;) {
     697             :       Instruction *I = &*(It++);
     698             :       auto II = dyn_cast<IntrinsicInst>(I);
     699             :       if (!II)
     700             :         continue;
     701             : 
     702           2 :       if (II->getIntrinsicID() == Intrinsic::stacksave) {
     703           0 :         IRBuilder<> IRB(II);
     704           0 :         Instruction *LI = IRB.CreateLoad(UnsafeStackPtr);
     705           0 :         LI->takeName(II);
     706           0 :         II->replaceAllUsesWith(LI);
     707           0 :         II->eraseFromParent();
     708           2 :       } else if (II->getIntrinsicID() == Intrinsic::stackrestore) {
     709           0 :         IRBuilder<> IRB(II);
     710           0 :         Instruction *SI = IRB.CreateStore(II->getArgOperand(0), UnsafeStackPtr);
     711           0 :         SI->takeName(II);
     712             :         assert(II->use_empty());
     713           0 :         II->eraseFromParent();
     714             :       }
     715             :     }
     716             :   }
     717         161 : }
     718             : 
     719           0 : bool SafeStack::ShouldInlinePointerAddress(CallSite &CS) {
     720             :   Function *Callee = CS.getCalledFunction();
     721           0 :   if (CS.hasFnAttr(Attribute::AlwaysInline) && isInlineViable(*Callee))
     722           0 :     return true;
     723           0 :   if (Callee->isInterposable() || Callee->hasFnAttribute(Attribute::NoInline) ||
     724           0 :       CS.isNoInline())
     725           0 :     return false;
     726             :   return true;
     727             : }
     728             : 
     729         161 : void SafeStack::TryInlinePointerAddress() {
     730         161 :   if (!isa<CallInst>(UnsafeStackPtr))
     731         159 :     return;
     732             : 
     733           6 :   if(F.hasFnAttribute(Attribute::OptimizeNone))
     734             :     return;
     735             : 
     736           6 :   CallSite CS(UnsafeStackPtr);
     737             :   Function *Callee = CS.getCalledFunction();
     738           6 :   if (!Callee || Callee->isDeclaration())
     739           3 :     return;
     740             : 
     741           3 :   if (!ShouldInlinePointerAddress(CS))
     742             :     return;
     743             : 
     744           2 :   InlineFunctionInfo IFI;
     745           2 :   InlineFunction(CS, IFI);
     746             : }
     747             : 
     748         190 : bool SafeStack::run() {
     749             :   assert(F.hasFnAttribute(Attribute::SafeStack) &&
     750             :          "Can't run SafeStack on a function without the attribute");
     751             :   assert(!F.isDeclaration() && "Can't run SafeStack on a function declaration");
     752             : 
     753             :   ++NumFunctions;
     754             : 
     755             :   SmallVector<AllocaInst *, 16> StaticAllocas;
     756             :   SmallVector<AllocaInst *, 4> DynamicAllocas;
     757             :   SmallVector<Argument *, 4> ByValArguments;
     758             :   SmallVector<ReturnInst *, 4> Returns;
     759             : 
     760             :   // Collect all points where stack gets unwound and needs to be restored
     761             :   // This is only necessary because the runtime (setjmp and unwind code) is
     762             :   // not aware of the unsafe stack and won't unwind/restore it properly.
     763             :   // To work around this problem without changing the runtime, we insert
     764             :   // instrumentation to restore the unsafe stack pointer when necessary.
     765             :   SmallVector<Instruction *, 4> StackRestorePoints;
     766             : 
     767             :   // Find all static and dynamic alloca instructions that must be moved to the
     768             :   // unsafe stack, all return instructions and stack restore points.
     769         190 :   findInsts(F, StaticAllocas, DynamicAllocas, ByValArguments, Returns,
     770             :             StackRestorePoints);
     771             : 
     772          44 :   if (StaticAllocas.empty() && DynamicAllocas.empty() &&
     773         225 :       ByValArguments.empty() && StackRestorePoints.empty())
     774             :     return false; // Nothing to do in this function.
     775             : 
     776             :   if (!StaticAllocas.empty() || !DynamicAllocas.empty() ||
     777             :       !ByValArguments.empty())
     778             :     ++NumUnsafeStackFunctions; // This function has the unsafe stack.
     779             : 
     780             :   if (!StackRestorePoints.empty())
     781             :     ++NumUnsafeStackRestorePointsFunctions;
     782             : 
     783         483 :   IRBuilder<> IRB(&F.front(), F.begin()->getFirstInsertionPt());
     784             :   // Calls must always have a debug location, or else inlining breaks. So
     785             :   // we explicitly set a artificial debug location here.
     786         161 :   if (DISubprogram *SP = F.getSubprogram())
     787           8 :     IRB.SetCurrentDebugLocation(DebugLoc::get(SP->getScopeLine(), 0, SP));
     788         161 :   if (SafeStackUsePointerAddress) {
     789           4 :     Value *Fn = F.getParent()->getOrInsertFunction(
     790           4 :         "__safestack_pointer_address", StackPtrTy->getPointerTo(0));
     791           4 :     UnsafeStackPtr = IRB.CreateCall(Fn);
     792             :   } else {
     793         157 :     UnsafeStackPtr = TL.getSafeStackPointerLocation(IRB);
     794             :   }
     795             : 
     796             :   // Load the current stack pointer (we'll also use it as a base pointer).
     797             :   // FIXME: use a dedicated register for it ?
     798             :   Instruction *BasePointer =
     799         161 :       IRB.CreateLoad(UnsafeStackPtr, false, "unsafe_stack_ptr");
     800             :   assert(BasePointer->getType() == StackPtrTy);
     801             : 
     802             :   AllocaInst *StackGuardSlot = nullptr;
     803             :   // FIXME: implement weaker forms of stack protector.
     804         322 :   if (F.hasFnAttribute(Attribute::StackProtect) ||
     805         322 :       F.hasFnAttribute(Attribute::StackProtectStrong) ||
     806         161 :       F.hasFnAttribute(Attribute::StackProtectReq)) {
     807          13 :     Value *StackGuard = getStackGuard(IRB, F);
     808          13 :     StackGuardSlot = IRB.CreateAlloca(StackPtrTy, nullptr);
     809          13 :     IRB.CreateStore(StackGuard, StackGuardSlot);
     810             : 
     811          26 :     for (ReturnInst *RI : Returns) {
     812          13 :       IRBuilder<> IRBRet(RI);
     813          13 :       checkStackGuard(IRBRet, F, *RI, StackGuardSlot, StackGuard);
     814             :     }
     815             :   }
     816             : 
     817             :   // The top of the unsafe stack after all unsafe static allocas are
     818             :   // allocated.
     819             :   Value *StaticTop =
     820         161 :       moveStaticAllocasToUnsafeStack(IRB, F, StaticAllocas, ByValArguments,
     821             :                                      Returns, BasePointer, StackGuardSlot);
     822             : 
     823             :   // Safe stack object that stores the current unsafe stack top. It is updated
     824             :   // as unsafe dynamic (non-constant-sized) allocas are allocated and freed.
     825             :   // This is only needed if we need to restore stack pointer after longjmp
     826             :   // or exceptions, and we have dynamic allocations.
     827             :   // FIXME: a better alternative might be to store the unsafe stack pointer
     828             :   // before setjmp / invoke instructions.
     829         161 :   AllocaInst *DynamicTop = createStackRestorePoints(
     830         161 :       IRB, F, StackRestorePoints, StaticTop, !DynamicAllocas.empty());
     831             : 
     832             :   // Handle dynamic allocas.
     833         161 :   moveDynamicAllocasToUnsafeStack(F, UnsafeStackPtr, DynamicTop,
     834             :                                   DynamicAllocas);
     835             : 
     836             :   // Restore the unsafe stack pointer before each return.
     837         332 :   for (ReturnInst *RI : Returns) {
     838         171 :     IRB.SetInsertPoint(RI);
     839         171 :     IRB.CreateStore(BasePointer, UnsafeStackPtr);
     840             :   }
     841             : 
     842         161 :   TryInlinePointerAddress();
     843             : 
     844             :   LLVM_DEBUG(dbgs() << "[SafeStack]     safestack applied\n");
     845             :   return true;
     846             : }
     847             : 
     848             : class SafeStackLegacyPass : public FunctionPass {
     849             :   const TargetMachine *TM = nullptr;
     850             : 
     851             : public:
     852             :   static char ID; // Pass identification, replacement for typeid..
     853             : 
     854       27550 :   SafeStackLegacyPass() : FunctionPass(ID) {
     855       27550 :     initializeSafeStackLegacyPassPass(*PassRegistry::getPassRegistry());
     856       27550 :   }
     857             : 
     858       27421 :   void getAnalysisUsage(AnalysisUsage &AU) const override {
     859             :     AU.addRequired<TargetPassConfig>();
     860             :     AU.addRequired<TargetLibraryInfoWrapperPass>();
     861             :     AU.addRequired<AssumptionCacheTracker>();
     862       27421 :   }
     863             : 
     864      406648 :   bool runOnFunction(Function &F) override {
     865             :     LLVM_DEBUG(dbgs() << "[SafeStack] Function: " << F.getName() << "\n");
     866             : 
     867      406648 :     if (!F.hasFnAttribute(Attribute::SafeStack)) {
     868             :       LLVM_DEBUG(dbgs() << "[SafeStack]     safestack is not requested"
     869             :                            " for this function\n");
     870             :       return false;
     871             :     }
     872             : 
     873         190 :     if (F.isDeclaration()) {
     874             :       LLVM_DEBUG(dbgs() << "[SafeStack]     function definition"
     875             :                            " is not available\n");
     876             :       return false;
     877             :     }
     878             : 
     879         190 :     TM = &getAnalysis<TargetPassConfig>().getTM<TargetMachine>();
     880         190 :     auto *TL = TM->getSubtargetImpl(F)->getTargetLowering();
     881         190 :     if (!TL)
     882           0 :       report_fatal_error("TargetLowering instance is required");
     883             : 
     884         190 :     auto *DL = &F.getParent()->getDataLayout();
     885         190 :     auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
     886         190 :     auto &ACT = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
     887             : 
     888             :     // Compute DT and LI only for functions that have the attribute.
     889             :     // This is only useful because the legacy pass manager doesn't let us
     890             :     // compute analyzes lazily.
     891             :     // In the backend pipeline, nothing preserves DT before SafeStack, so we
     892             :     // would otherwise always compute it wastefully, even if there is no
     893             :     // function with the safestack attribute.
     894         190 :     DominatorTree DT(F);
     895         190 :     LoopInfo LI(DT);
     896             : 
     897         190 :     ScalarEvolution SE(F, TLI, ACT, DT, LI);
     898             : 
     899         190 :     return SafeStack(F, *TL, *DL, SE).run();
     900             :   }
     901             : };
     902             : 
     903             : } // end anonymous namespace
     904             : 
     905             : char SafeStackLegacyPass::ID = 0;
     906             : 
     907       39044 : INITIALIZE_PASS_BEGIN(SafeStackLegacyPass, DEBUG_TYPE,
     908             :                       "Safe Stack instrumentation pass", false, false)
     909       39044 : INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)
     910      130700 : INITIALIZE_PASS_END(SafeStackLegacyPass, DEBUG_TYPE,
     911             :                     "Safe Stack instrumentation pass", false, false)
     912             : 
     913       27453 : FunctionPass *llvm::createSafeStackPass() { return new SafeStackLegacyPass(); }

Generated by: LCOV version 1.13