1//===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
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 file is a part of AddressSanitizer, an address sanity checker.
11// Details of the algorithm:
12//  http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
13//
14//===----------------------------------------------------------------------===//
15
16#define DEBUG_TYPE "asan"
17
18#include "llvm/Transforms/Instrumentation.h"
19#include "llvm/ADT/ArrayRef.h"
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/DepthFirstIterator.h"
22#include "llvm/ADT/OwningPtr.h"
23#include "llvm/ADT/SmallSet.h"
24#include "llvm/ADT/SmallString.h"
25#include "llvm/ADT/SmallVector.h"
26#include "llvm/ADT/StringExtras.h"
27#include "llvm/ADT/Triple.h"
28#include "llvm/DIBuilder.h"
29#include "llvm/IR/DataLayout.h"
30#include "llvm/IR/Function.h"
31#include "llvm/IR/IRBuilder.h"
32#include "llvm/IR/InlineAsm.h"
33#include "llvm/IR/IntrinsicInst.h"
34#include "llvm/IR/LLVMContext.h"
35#include "llvm/IR/Module.h"
36#include "llvm/IR/Type.h"
37#include "llvm/InstVisitor.h"
38#include "llvm/Support/CallSite.h"
39#include "llvm/Support/CommandLine.h"
40#include "llvm/Support/DataTypes.h"
41#include "llvm/Support/Debug.h"
42#include "llvm/Support/Endian.h"
43#include "llvm/Support/raw_ostream.h"
44#include "llvm/Support/system_error.h"
45#include "llvm/Transforms/Utils/BasicBlockUtils.h"
46#include "llvm/Transforms/Utils/Cloning.h"
47#include "llvm/Transforms/Utils/Local.h"
48#include "llvm/Transforms/Utils/ModuleUtils.h"
49#include "llvm/Transforms/Utils/SpecialCaseList.h"
50#include <algorithm>
51#include <string>
52
53using namespace llvm;
54
55static const uint64_t kDefaultShadowScale = 3;
56static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
57static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
58static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
59static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
60static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
61
62static const size_t kMaxStackMallocSize = 1 << 16;  // 64K
63static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
64static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
65
66static const char *const kAsanModuleCtorName = "asan.module_ctor";
67static const char *const kAsanModuleDtorName = "asan.module_dtor";
68static const int         kAsanCtorAndCtorPriority = 1;
69static const char *const kAsanReportErrorTemplate = "__asan_report_";
70static const char *const kAsanReportLoadN = "__asan_report_load_n";
71static const char *const kAsanReportStoreN = "__asan_report_store_n";
72static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
73static const char *const kAsanUnregisterGlobalsName =
74    "__asan_unregister_globals";
75static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
76static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
77static const char *const kAsanInitName = "__asan_init_v3";
78static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
79static const char *const kAsanMappingOffsetName = "__asan_mapping_offset";
80static const char *const kAsanMappingScaleName = "__asan_mapping_scale";
81static const char *const kAsanStackMallocName = "__asan_stack_malloc";
82static const char *const kAsanStackFreeName = "__asan_stack_free";
83static const char *const kAsanGenPrefix = "__asan_gen_";
84static const char *const kAsanPoisonStackMemoryName =
85    "__asan_poison_stack_memory";
86static const char *const kAsanUnpoisonStackMemoryName =
87    "__asan_unpoison_stack_memory";
88
89static const int kAsanStackLeftRedzoneMagic = 0xf1;
90static const int kAsanStackMidRedzoneMagic = 0xf2;
91static const int kAsanStackRightRedzoneMagic = 0xf3;
92static const int kAsanStackPartialRedzoneMagic = 0xf4;
93
94// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
95static const size_t kNumberOfAccessSizes = 5;
96
97// Command-line flags.
98
99// This flag may need to be replaced with -f[no-]asan-reads.
100static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
101       cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
102static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
103       cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
104static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
105       cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
106       cl::Hidden, cl::init(true));
107static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
108       cl::desc("use instrumentation with slow path for all accesses"),
109       cl::Hidden, cl::init(false));
110// This flag limits the number of instructions to be instrumented
111// in any given BB. Normally, this should be set to unlimited (INT_MAX),
112// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
113// set it to 10000.
114static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
115       cl::init(10000),
116       cl::desc("maximal number of instructions to instrument in any given BB"),
117       cl::Hidden);
118// This flag may need to be replaced with -f[no]asan-stack.
119static cl::opt<bool> ClStack("asan-stack",
120       cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
121// This flag may need to be replaced with -f[no]asan-use-after-return.
122static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
123       cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
124// This flag may need to be replaced with -f[no]asan-globals.
125static cl::opt<bool> ClGlobals("asan-globals",
126       cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
127static cl::opt<bool> ClInitializers("asan-initialization-order",
128       cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
129static cl::opt<bool> ClMemIntrin("asan-memintrin",
130       cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
131static cl::opt<bool> ClRealignStack("asan-realign-stack",
132       cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
133static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
134       cl::desc("File containing the list of objects to ignore "
135                "during instrumentation"), cl::Hidden);
136
137// This is an experimental feature that will allow to choose between
138// instrumented and non-instrumented code at link-time.
139// If this option is on, just before instrumenting a function we create its
140// clone; if the function is not changed by asan the clone is deleted.
141// If we end up with a clone, we put the instrumented function into a section
142// called "ASAN" and the uninstrumented function into a section called "NOASAN".
143//
144// This is still a prototype, we need to figure out a way to keep two copies of
145// a function so that the linker can easily choose one of them.
146static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
147       cl::desc("Keep uninstrumented copies of functions"),
148       cl::Hidden, cl::init(false));
149
150// These flags allow to change the shadow mapping.
151// The shadow mapping looks like
152//    Shadow = (Mem >> scale) + (1 << offset_log)
153static cl::opt<int> ClMappingScale("asan-mapping-scale",
154       cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
155static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
156       cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
157static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
158       cl::desc("Use short immediate constant as the mapping offset for 64bit"),
159       cl::Hidden, cl::init(true));
160
161// Optimization flags. Not user visible, used mostly for testing
162// and benchmarking the tool.
163static cl::opt<bool> ClOpt("asan-opt",
164       cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
165static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
166       cl::desc("Instrument the same temp just once"), cl::Hidden,
167       cl::init(true));
168static cl::opt<bool> ClOptGlobals("asan-opt-globals",
169       cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
170
171static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
172       cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
173       cl::Hidden, cl::init(false));
174
175// Debug flags.
176static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
177                            cl::init(0));
178static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
179                                 cl::Hidden, cl::init(0));
180static cl::opt<std::string> ClDebugFunc("asan-debug-func",
181                                        cl::Hidden, cl::desc("Debug func"));
182static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
183                               cl::Hidden, cl::init(-1));
184static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
185                               cl::Hidden, cl::init(-1));
186
187namespace {
188/// A set of dynamically initialized globals extracted from metadata.
189class SetOfDynamicallyInitializedGlobals {
190 public:
191  void Init(Module& M) {
192    // Clang generates metadata identifying all dynamically initialized globals.
193    NamedMDNode *DynamicGlobals =
194        M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
195    if (!DynamicGlobals)
196      return;
197    for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
198      MDNode *MDN = DynamicGlobals->getOperand(i);
199      assert(MDN->getNumOperands() == 1);
200      Value *VG = MDN->getOperand(0);
201      // The optimizer may optimize away a global entirely, in which case we
202      // cannot instrument access to it.
203      if (!VG)
204        continue;
205      DynInitGlobals.insert(cast<GlobalVariable>(VG));
206    }
207  }
208  bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
209 private:
210  SmallSet<GlobalValue*, 32> DynInitGlobals;
211};
212
213/// This struct defines the shadow mapping using the rule:
214///   shadow = (mem >> Scale) ADD-or-OR Offset.
215struct ShadowMapping {
216  int Scale;
217  uint64_t Offset;
218  bool OrShadowOffset;
219};
220
221static ShadowMapping getShadowMapping(const Module &M, int LongSize,
222                                      bool ZeroBaseShadow) {
223  llvm::Triple TargetTriple(M.getTargetTriple());
224  bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
225  bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
226  bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
227                 TargetTriple.getArch() == llvm::Triple::ppc64le;
228  bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
229  bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
230                  TargetTriple.getArch() == llvm::Triple::mipsel;
231
232  ShadowMapping Mapping;
233
234  // OR-ing shadow offset if more efficient (at least on x86),
235  // but on ppc64 we have to use add since the shadow offset is not neccesary
236  // 1/8-th of the address space.
237  Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
238
239  Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
240      (LongSize == 32 ?
241       (IsMIPS32 ? kMIPS32_ShadowOffset32 : kDefaultShadowOffset32) :
242       IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
243  if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
244    assert(LongSize == 64);
245    Mapping.Offset = kDefaultShort64bitShadowOffset;
246  }
247  if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
248    // Zero offset log is the special case.
249    Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
250  }
251
252  Mapping.Scale = kDefaultShadowScale;
253  if (ClMappingScale) {
254    Mapping.Scale = ClMappingScale;
255  }
256
257  return Mapping;
258}
259
260static size_t RedzoneSizeForScale(int MappingScale) {
261  // Redzone used for stack and globals is at least 32 bytes.
262  // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
263  return std::max(32U, 1U << MappingScale);
264}
265
266/// AddressSanitizer: instrument the code in module to find memory bugs.
267struct AddressSanitizer : public FunctionPass {
268  AddressSanitizer(bool CheckInitOrder = true,
269                   bool CheckUseAfterReturn = false,
270                   bool CheckLifetime = false,
271                   StringRef BlacklistFile = StringRef(),
272                   bool ZeroBaseShadow = false)
273      : FunctionPass(ID),
274        CheckInitOrder(CheckInitOrder || ClInitializers),
275        CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
276        CheckLifetime(CheckLifetime || ClCheckLifetime),
277        BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
278                                            : BlacklistFile),
279        ZeroBaseShadow(ZeroBaseShadow) {}
280  virtual const char *getPassName() const {
281    return "AddressSanitizerFunctionPass";
282  }
283  void instrumentMop(Instruction *I);
284  void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
285                         Value *Addr, uint32_t TypeSize, bool IsWrite,
286                         Value *SizeArgument);
287  Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
288                           Value *ShadowValue, uint32_t TypeSize);
289  Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
290                                 bool IsWrite, size_t AccessSizeIndex,
291                                 Value *SizeArgument);
292  bool instrumentMemIntrinsic(MemIntrinsic *MI);
293  void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
294                                   Value *Size,
295                                   Instruction *InsertBefore, bool IsWrite);
296  Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
297  bool runOnFunction(Function &F);
298  bool maybeInsertAsanInitAtFunctionEntry(Function &F);
299  void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
300  virtual bool doInitialization(Module &M);
301  static char ID;  // Pass identification, replacement for typeid
302
303 private:
304  void initializeCallbacks(Module &M);
305
306  bool ShouldInstrumentGlobal(GlobalVariable *G);
307  bool LooksLikeCodeInBug11395(Instruction *I);
308  void FindDynamicInitializers(Module &M);
309
310  bool CheckInitOrder;
311  bool CheckUseAfterReturn;
312  bool CheckLifetime;
313  SmallString<64> BlacklistFile;
314  bool ZeroBaseShadow;
315
316  LLVMContext *C;
317  DataLayout *TD;
318  int LongSize;
319  Type *IntptrTy;
320  ShadowMapping Mapping;
321  Function *AsanCtorFunction;
322  Function *AsanInitFunction;
323  Function *AsanHandleNoReturnFunc;
324  OwningPtr<SpecialCaseList> BL;
325  // This array is indexed by AccessIsWrite and log2(AccessSize).
326  Function *AsanErrorCallback[2][kNumberOfAccessSizes];
327  // This array is indexed by AccessIsWrite.
328  Function *AsanErrorCallbackSized[2];
329  InlineAsm *EmptyAsm;
330  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
331
332  friend struct FunctionStackPoisoner;
333};
334
335class AddressSanitizerModule : public ModulePass {
336 public:
337  AddressSanitizerModule(bool CheckInitOrder = true,
338                         StringRef BlacklistFile = StringRef(),
339                         bool ZeroBaseShadow = false)
340      : ModulePass(ID),
341        CheckInitOrder(CheckInitOrder || ClInitializers),
342        BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
343                                            : BlacklistFile),
344        ZeroBaseShadow(ZeroBaseShadow) {}
345  bool runOnModule(Module &M);
346  static char ID;  // Pass identification, replacement for typeid
347  virtual const char *getPassName() const {
348    return "AddressSanitizerModule";
349  }
350
351 private:
352  void initializeCallbacks(Module &M);
353
354  bool ShouldInstrumentGlobal(GlobalVariable *G);
355  void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
356  size_t RedzoneSize() const {
357    return RedzoneSizeForScale(Mapping.Scale);
358  }
359
360  bool CheckInitOrder;
361  SmallString<64> BlacklistFile;
362  bool ZeroBaseShadow;
363
364  OwningPtr<SpecialCaseList> BL;
365  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
366  Type *IntptrTy;
367  LLVMContext *C;
368  DataLayout *TD;
369  ShadowMapping Mapping;
370  Function *AsanPoisonGlobals;
371  Function *AsanUnpoisonGlobals;
372  Function *AsanRegisterGlobals;
373  Function *AsanUnregisterGlobals;
374};
375
376// Stack poisoning does not play well with exception handling.
377// When an exception is thrown, we essentially bypass the code
378// that unpoisones the stack. This is why the run-time library has
379// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
380// stack in the interceptor. This however does not work inside the
381// actual function which catches the exception. Most likely because the
382// compiler hoists the load of the shadow value somewhere too high.
383// This causes asan to report a non-existing bug on 453.povray.
384// It sounds like an LLVM bug.
385struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
386  Function &F;
387  AddressSanitizer &ASan;
388  DIBuilder DIB;
389  LLVMContext *C;
390  Type *IntptrTy;
391  Type *IntptrPtrTy;
392  ShadowMapping Mapping;
393
394  SmallVector<AllocaInst*, 16> AllocaVec;
395  SmallVector<Instruction*, 8> RetVec;
396  uint64_t TotalStackSize;
397  unsigned StackAlignment;
398
399  Function *AsanStackMallocFunc, *AsanStackFreeFunc;
400  Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
401
402  // Stores a place and arguments of poisoning/unpoisoning call for alloca.
403  struct AllocaPoisonCall {
404    IntrinsicInst *InsBefore;
405    uint64_t Size;
406    bool DoPoison;
407  };
408  SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
409
410  // Maps Value to an AllocaInst from which the Value is originated.
411  typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
412  AllocaForValueMapTy AllocaForValue;
413
414  FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
415      : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
416        IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
417        Mapping(ASan.Mapping),
418        TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
419
420  bool runOnFunction() {
421    if (!ClStack) return false;
422    // Collect alloca, ret, lifetime instructions etc.
423    for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
424         DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
425      BasicBlock *BB = *DI;
426      visit(*BB);
427    }
428    if (AllocaVec.empty()) return false;
429
430    initializeCallbacks(*F.getParent());
431
432    poisonStack();
433
434    if (ClDebugStack) {
435      DEBUG(dbgs() << F);
436    }
437    return true;
438  }
439
440  // Finds all static Alloca instructions and puts
441  // poisoned red zones around all of them.
442  // Then unpoison everything back before the function returns.
443  void poisonStack();
444
445  // ----------------------- Visitors.
446  /// \brief Collect all Ret instructions.
447  void visitReturnInst(ReturnInst &RI) {
448    RetVec.push_back(&RI);
449  }
450
451  /// \brief Collect Alloca instructions we want (and can) handle.
452  void visitAllocaInst(AllocaInst &AI) {
453    if (!isInterestingAlloca(AI)) return;
454
455    StackAlignment = std::max(StackAlignment, AI.getAlignment());
456    AllocaVec.push_back(&AI);
457    uint64_t AlignedSize = getAlignedAllocaSize(&AI);
458    TotalStackSize += AlignedSize;
459  }
460
461  /// \brief Collect lifetime intrinsic calls to check for use-after-scope
462  /// errors.
463  void visitIntrinsicInst(IntrinsicInst &II) {
464    if (!ASan.CheckLifetime) return;
465    Intrinsic::ID ID = II.getIntrinsicID();
466    if (ID != Intrinsic::lifetime_start &&
467        ID != Intrinsic::lifetime_end)
468      return;
469    // Found lifetime intrinsic, add ASan instrumentation if necessary.
470    ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
471    // If size argument is undefined, don't do anything.
472    if (Size->isMinusOne()) return;
473    // Check that size doesn't saturate uint64_t and can
474    // be stored in IntptrTy.
475    const uint64_t SizeValue = Size->getValue().getLimitedValue();
476    if (SizeValue == ~0ULL ||
477        !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
478      return;
479    // Find alloca instruction that corresponds to llvm.lifetime argument.
480    AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
481    if (!AI) return;
482    bool DoPoison = (ID == Intrinsic::lifetime_end);
483    AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
484    AllocaPoisonCallVec.push_back(APC);
485  }
486
487  // ---------------------- Helpers.
488  void initializeCallbacks(Module &M);
489
490  // Check if we want (and can) handle this alloca.
491  bool isInterestingAlloca(AllocaInst &AI) {
492    return (!AI.isArrayAllocation() &&
493            AI.isStaticAlloca() &&
494            AI.getAlignment() <= RedzoneSize() &&
495            AI.getAllocatedType()->isSized());
496  }
497
498  size_t RedzoneSize() const {
499    return RedzoneSizeForScale(Mapping.Scale);
500  }
501  uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
502    Type *Ty = AI->getAllocatedType();
503    uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
504    return SizeInBytes;
505  }
506  uint64_t getAlignedSize(uint64_t SizeInBytes) {
507    size_t RZ = RedzoneSize();
508    return ((SizeInBytes + RZ - 1) / RZ) * RZ;
509  }
510  uint64_t getAlignedAllocaSize(AllocaInst *AI) {
511    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
512    return getAlignedSize(SizeInBytes);
513  }
514  /// Finds alloca where the value comes from.
515  AllocaInst *findAllocaForValue(Value *V);
516  void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
517                      Value *ShadowBase, bool DoPoison);
518  void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
519};
520
521}  // namespace
522
523char AddressSanitizer::ID = 0;
524INITIALIZE_PASS(AddressSanitizer, "asan",
525    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
526    false, false)
527FunctionPass *llvm::createAddressSanitizerFunctionPass(
528    bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
529    StringRef BlacklistFile, bool ZeroBaseShadow) {
530  return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
531                              CheckLifetime, BlacklistFile, ZeroBaseShadow);
532}
533
534char AddressSanitizerModule::ID = 0;
535INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
536    "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
537    "ModulePass", false, false)
538ModulePass *llvm::createAddressSanitizerModulePass(
539    bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
540  return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
541                                    ZeroBaseShadow);
542}
543
544static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
545  size_t Res = countTrailingZeros(TypeSize / 8);
546  assert(Res < kNumberOfAccessSizes);
547  return Res;
548}
549
550// \brief Create a constant for Str so that we can pass it to the run-time lib.
551static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
552  Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
553  GlobalVariable *GV = new GlobalVariable(M, StrConst->getType(), true,
554                            GlobalValue::InternalLinkage, StrConst,
555                            kAsanGenPrefix);
556  GV->setUnnamedAddr(true);  // Ok to merge these.
557  GV->setAlignment(1);  // Strings may not be merged w/o setting align 1.
558  return GV;
559}
560
561static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
562  return G->getName().find(kAsanGenPrefix) == 0;
563}
564
565Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
566  // Shadow >> scale
567  Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
568  if (Mapping.Offset == 0)
569    return Shadow;
570  // (Shadow >> scale) | offset
571  if (Mapping.OrShadowOffset)
572    return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
573  else
574    return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
575}
576
577void AddressSanitizer::instrumentMemIntrinsicParam(
578    Instruction *OrigIns,
579    Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
580  IRBuilder<> IRB(InsertBefore);
581  if (Size->getType() != IntptrTy)
582    Size = IRB.CreateIntCast(Size, IntptrTy, false);
583  // Check the first byte.
584  instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
585  // Check the last byte.
586  IRB.SetInsertPoint(InsertBefore);
587  Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
588  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
589  Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
590  instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
591}
592
593// Instrument memset/memmove/memcpy
594bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
595  Value *Dst = MI->getDest();
596  MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
597  Value *Src = MemTran ? MemTran->getSource() : 0;
598  Value *Length = MI->getLength();
599
600  Constant *ConstLength = dyn_cast<Constant>(Length);
601  Instruction *InsertBefore = MI;
602  if (ConstLength) {
603    if (ConstLength->isNullValue()) return false;
604  } else {
605    // The size is not a constant so it could be zero -- check at run-time.
606    IRBuilder<> IRB(InsertBefore);
607
608    Value *Cmp = IRB.CreateICmpNE(Length,
609                                  Constant::getNullValue(Length->getType()));
610    InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
611  }
612
613  instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
614  if (Src)
615    instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
616  return true;
617}
618
619// If I is an interesting memory access, return the PointerOperand
620// and set IsWrite. Otherwise return NULL.
621static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
622  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
623    if (!ClInstrumentReads) return NULL;
624    *IsWrite = false;
625    return LI->getPointerOperand();
626  }
627  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
628    if (!ClInstrumentWrites) return NULL;
629    *IsWrite = true;
630    return SI->getPointerOperand();
631  }
632  if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
633    if (!ClInstrumentAtomics) return NULL;
634    *IsWrite = true;
635    return RMW->getPointerOperand();
636  }
637  if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
638    if (!ClInstrumentAtomics) return NULL;
639    *IsWrite = true;
640    return XCHG->getPointerOperand();
641  }
642  return NULL;
643}
644
645void AddressSanitizer::instrumentMop(Instruction *I) {
646  bool IsWrite = false;
647  Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
648  assert(Addr);
649  if (ClOpt && ClOptGlobals) {
650    if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
651      // If initialization order checking is disabled, a simple access to a
652      // dynamically initialized global is always valid.
653      if (!CheckInitOrder)
654        return;
655      // If a global variable does not have dynamic initialization we don't
656      // have to instrument it.  However, if a global does not have initailizer
657      // at all, we assume it has dynamic initializer (in other TU).
658      if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
659        return;
660    }
661  }
662
663  Type *OrigPtrTy = Addr->getType();
664  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
665
666  assert(OrigTy->isSized());
667  uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
668
669  assert((TypeSize % 8) == 0);
670
671  // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
672  if (TypeSize == 8  || TypeSize == 16 ||
673      TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
674    return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
675  // Instrument unusual size (but still multiple of 8).
676  // We can not do it with a single check, so we do 1-byte check for the first
677  // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
678  // to report the actual access size.
679  IRBuilder<> IRB(I);
680  Value *LastByte =  IRB.CreateIntToPtr(
681      IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
682                    ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
683      OrigPtrTy);
684  Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
685  instrumentAddress(I, I, Addr, 8, IsWrite, Size);
686  instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
687}
688
689// Validate the result of Module::getOrInsertFunction called for an interface
690// function of AddressSanitizer. If the instrumented module defines a function
691// with the same name, their prototypes must match, otherwise
692// getOrInsertFunction returns a bitcast.
693static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
694  if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
695  FuncOrBitcast->dump();
696  report_fatal_error("trying to redefine an AddressSanitizer "
697                     "interface function");
698}
699
700Instruction *AddressSanitizer::generateCrashCode(
701    Instruction *InsertBefore, Value *Addr,
702    bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
703  IRBuilder<> IRB(InsertBefore);
704  CallInst *Call = SizeArgument
705    ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
706    : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
707
708  // We don't do Call->setDoesNotReturn() because the BB already has
709  // UnreachableInst at the end.
710  // This EmptyAsm is required to avoid callback merge.
711  IRB.CreateCall(EmptyAsm);
712  return Call;
713}
714
715Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
716                                            Value *ShadowValue,
717                                            uint32_t TypeSize) {
718  size_t Granularity = 1 << Mapping.Scale;
719  // Addr & (Granularity - 1)
720  Value *LastAccessedByte = IRB.CreateAnd(
721      AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
722  // (Addr & (Granularity - 1)) + size - 1
723  if (TypeSize / 8 > 1)
724    LastAccessedByte = IRB.CreateAdd(
725        LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
726  // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
727  LastAccessedByte = IRB.CreateIntCast(
728      LastAccessedByte, ShadowValue->getType(), false);
729  // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
730  return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
731}
732
733void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
734                                         Instruction *InsertBefore,
735                                         Value *Addr, uint32_t TypeSize,
736                                         bool IsWrite, Value *SizeArgument) {
737  IRBuilder<> IRB(InsertBefore);
738  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
739
740  Type *ShadowTy  = IntegerType::get(
741      *C, std::max(8U, TypeSize >> Mapping.Scale));
742  Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
743  Value *ShadowPtr = memToShadow(AddrLong, IRB);
744  Value *CmpVal = Constant::getNullValue(ShadowTy);
745  Value *ShadowValue = IRB.CreateLoad(
746      IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
747
748  Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
749  size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
750  size_t Granularity = 1 << Mapping.Scale;
751  TerminatorInst *CrashTerm = 0;
752
753  if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
754    TerminatorInst *CheckTerm =
755        SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
756    assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
757    BasicBlock *NextBB = CheckTerm->getSuccessor(0);
758    IRB.SetInsertPoint(CheckTerm);
759    Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
760    BasicBlock *CrashBlock =
761        BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
762    CrashTerm = new UnreachableInst(*C, CrashBlock);
763    BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
764    ReplaceInstWithInst(CheckTerm, NewTerm);
765  } else {
766    CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
767  }
768
769  Instruction *Crash = generateCrashCode(
770      CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
771  Crash->setDebugLoc(OrigIns->getDebugLoc());
772}
773
774void AddressSanitizerModule::createInitializerPoisonCalls(
775    Module &M, GlobalValue *ModuleName) {
776  // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
777  Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
778  // If that function is not present, this TU contains no globals, or they have
779  // all been optimized away
780  if (!GlobalInit)
781    return;
782
783  // Set up the arguments to our poison/unpoison functions.
784  IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
785
786  // Add a call to poison all external globals before the given function starts.
787  Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
788  IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
789
790  // Add calls to unpoison all globals before each return instruction.
791  for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
792      I != E; ++I) {
793    if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
794      CallInst::Create(AsanUnpoisonGlobals, "", RI);
795    }
796  }
797}
798
799bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
800  Type *Ty = cast<PointerType>(G->getType())->getElementType();
801  DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
802
803  if (BL->isIn(*G)) return false;
804  if (!Ty->isSized()) return false;
805  if (!G->hasInitializer()) return false;
806  if (GlobalWasGeneratedByAsan(G)) return false;  // Our own global.
807  // Touch only those globals that will not be defined in other modules.
808  // Don't handle ODR type linkages since other modules may be built w/o asan.
809  if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
810      G->getLinkage() != GlobalVariable::PrivateLinkage &&
811      G->getLinkage() != GlobalVariable::InternalLinkage)
812    return false;
813  // Two problems with thread-locals:
814  //   - The address of the main thread's copy can't be computed at link-time.
815  //   - Need to poison all copies, not just the main thread's one.
816  if (G->isThreadLocal())
817    return false;
818  // For now, just ignore this Alloca if the alignment is large.
819  if (G->getAlignment() > RedzoneSize()) return false;
820
821  // Ignore all the globals with the names starting with "\01L_OBJC_".
822  // Many of those are put into the .cstring section. The linker compresses
823  // that section by removing the spare \0s after the string terminator, so
824  // our redzones get broken.
825  if ((G->getName().find("\01L_OBJC_") == 0) ||
826      (G->getName().find("\01l_OBJC_") == 0)) {
827    DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
828    return false;
829  }
830
831  if (G->hasSection()) {
832    StringRef Section(G->getSection());
833    // Ignore the globals from the __OBJC section. The ObjC runtime assumes
834    // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
835    // them.
836    if ((Section.find("__OBJC,") == 0) ||
837        (Section.find("__DATA, __objc_") == 0)) {
838      DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
839      return false;
840    }
841    // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
842    // Constant CFString instances are compiled in the following way:
843    //  -- the string buffer is emitted into
844    //     __TEXT,__cstring,cstring_literals
845    //  -- the constant NSConstantString structure referencing that buffer
846    //     is placed into __DATA,__cfstring
847    // Therefore there's no point in placing redzones into __DATA,__cfstring.
848    // Moreover, it causes the linker to crash on OS X 10.7
849    if (Section.find("__DATA,__cfstring") == 0) {
850      DEBUG(dbgs() << "Ignoring CFString: " << *G);
851      return false;
852    }
853  }
854
855  return true;
856}
857
858void AddressSanitizerModule::initializeCallbacks(Module &M) {
859  IRBuilder<> IRB(*C);
860  // Declare our poisoning and unpoisoning functions.
861  AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
862      kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
863  AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
864  AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
865      kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
866  AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
867  // Declare functions that register/unregister globals.
868  AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
869      kAsanRegisterGlobalsName, IRB.getVoidTy(),
870      IntptrTy, IntptrTy, NULL));
871  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
872  AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
873      kAsanUnregisterGlobalsName,
874      IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
875  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
876}
877
878// This function replaces all global variables with new variables that have
879// trailing redzones. It also creates a function that poisons
880// redzones and inserts this function into llvm.global_ctors.
881bool AddressSanitizerModule::runOnModule(Module &M) {
882  if (!ClGlobals) return false;
883  TD = getAnalysisIfAvailable<DataLayout>();
884  if (!TD)
885    return false;
886  BL.reset(new SpecialCaseList(BlacklistFile));
887  if (BL->isIn(M)) return false;
888  C = &(M.getContext());
889  int LongSize = TD->getPointerSizeInBits();
890  IntptrTy = Type::getIntNTy(*C, LongSize);
891  Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
892  initializeCallbacks(M);
893  DynamicallyInitializedGlobals.Init(M);
894
895  SmallVector<GlobalVariable *, 16> GlobalsToChange;
896
897  for (Module::GlobalListType::iterator G = M.global_begin(),
898       E = M.global_end(); G != E; ++G) {
899    if (ShouldInstrumentGlobal(G))
900      GlobalsToChange.push_back(G);
901  }
902
903  size_t n = GlobalsToChange.size();
904  if (n == 0) return false;
905
906  // A global is described by a structure
907  //   size_t beg;
908  //   size_t size;
909  //   size_t size_with_redzone;
910  //   const char *name;
911  //   const char *module_name;
912  //   size_t has_dynamic_init;
913  // We initialize an array of such structures and pass it to a run-time call.
914  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
915                                               IntptrTy, IntptrTy,
916                                               IntptrTy, IntptrTy, NULL);
917  SmallVector<Constant *, 16> Initializers(n), DynamicInit;
918
919
920  Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
921  assert(CtorFunc);
922  IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
923
924  bool HasDynamicallyInitializedGlobals = false;
925
926  GlobalVariable *ModuleName = createPrivateGlobalForString(
927      M, M.getModuleIdentifier());
928  // We shouldn't merge same module names, as this string serves as unique
929  // module ID in runtime.
930  ModuleName->setUnnamedAddr(false);
931
932  for (size_t i = 0; i < n; i++) {
933    static const uint64_t kMaxGlobalRedzone = 1 << 18;
934    GlobalVariable *G = GlobalsToChange[i];
935    PointerType *PtrTy = cast<PointerType>(G->getType());
936    Type *Ty = PtrTy->getElementType();
937    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
938    uint64_t MinRZ = RedzoneSize();
939    // MinRZ <= RZ <= kMaxGlobalRedzone
940    // and trying to make RZ to be ~ 1/4 of SizeInBytes.
941    uint64_t RZ = std::max(MinRZ,
942                         std::min(kMaxGlobalRedzone,
943                                  (SizeInBytes / MinRZ / 4) * MinRZ));
944    uint64_t RightRedzoneSize = RZ;
945    // Round up to MinRZ
946    if (SizeInBytes % MinRZ)
947      RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
948    assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
949    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
950    // Determine whether this global should be poisoned in initialization.
951    bool GlobalHasDynamicInitializer =
952        DynamicallyInitializedGlobals.Contains(G);
953    // Don't check initialization order if this global is blacklisted.
954    GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
955
956    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
957    Constant *NewInitializer = ConstantStruct::get(
958        NewTy, G->getInitializer(),
959        Constant::getNullValue(RightRedZoneTy), NULL);
960
961    GlobalVariable *Name = createPrivateGlobalForString(M, G->getName());
962
963    // Create a new global variable with enough space for a redzone.
964    GlobalValue::LinkageTypes Linkage = G->getLinkage();
965    if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
966      Linkage = GlobalValue::InternalLinkage;
967    GlobalVariable *NewGlobal = new GlobalVariable(
968        M, NewTy, G->isConstant(), Linkage,
969        NewInitializer, "", G, G->getThreadLocalMode());
970    NewGlobal->copyAttributesFrom(G);
971    NewGlobal->setAlignment(MinRZ);
972
973    Value *Indices2[2];
974    Indices2[0] = IRB.getInt32(0);
975    Indices2[1] = IRB.getInt32(0);
976
977    G->replaceAllUsesWith(
978        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
979    NewGlobal->takeName(G);
980    G->eraseFromParent();
981
982    Initializers[i] = ConstantStruct::get(
983        GlobalStructTy,
984        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
985        ConstantInt::get(IntptrTy, SizeInBytes),
986        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
987        ConstantExpr::getPointerCast(Name, IntptrTy),
988        ConstantExpr::getPointerCast(ModuleName, IntptrTy),
989        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
990        NULL);
991
992    // Populate the first and last globals declared in this TU.
993    if (CheckInitOrder && GlobalHasDynamicInitializer)
994      HasDynamicallyInitializedGlobals = true;
995
996    DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
997  }
998
999  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1000  GlobalVariable *AllGlobals = new GlobalVariable(
1001      M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1002      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1003
1004  // Create calls for poisoning before initializers run and unpoisoning after.
1005  if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1006    createInitializerPoisonCalls(M, ModuleName);
1007  IRB.CreateCall2(AsanRegisterGlobals,
1008                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
1009                  ConstantInt::get(IntptrTy, n));
1010
1011  // We also need to unregister globals at the end, e.g. when a shared library
1012  // gets closed.
1013  Function *AsanDtorFunction = Function::Create(
1014      FunctionType::get(Type::getVoidTy(*C), false),
1015      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1016  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1017  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1018  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1019                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
1020                       ConstantInt::get(IntptrTy, n));
1021  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1022
1023  DEBUG(dbgs() << M);
1024  return true;
1025}
1026
1027void AddressSanitizer::initializeCallbacks(Module &M) {
1028  IRBuilder<> IRB(*C);
1029  // Create __asan_report* callbacks.
1030  for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1031    for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1032         AccessSizeIndex++) {
1033      // IsWrite and TypeSize are encoded in the function name.
1034      std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1035          (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1036      // If we are merging crash callbacks, they have two parameters.
1037      AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1038          checkInterfaceFunction(M.getOrInsertFunction(
1039              FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1040    }
1041  }
1042  AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1043              kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1044  AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1045              kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1046
1047  AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1048      kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1049  // We insert an empty inline asm after __asan_report* to avoid callback merge.
1050  EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1051                            StringRef(""), StringRef(""),
1052                            /*hasSideEffects=*/true);
1053}
1054
1055void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1056  // Tell the values of mapping offset and scale to the run-time.
1057  GlobalValue *asan_mapping_offset =
1058      new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1059                     ConstantInt::get(IntptrTy, Mapping.Offset),
1060                     kAsanMappingOffsetName);
1061  // Read the global, otherwise it may be optimized away.
1062  IRB.CreateLoad(asan_mapping_offset, true);
1063
1064  GlobalValue *asan_mapping_scale =
1065      new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1066                         ConstantInt::get(IntptrTy, Mapping.Scale),
1067                         kAsanMappingScaleName);
1068  // Read the global, otherwise it may be optimized away.
1069  IRB.CreateLoad(asan_mapping_scale, true);
1070}
1071
1072// virtual
1073bool AddressSanitizer::doInitialization(Module &M) {
1074  // Initialize the private fields. No one has accessed them before.
1075  TD = getAnalysisIfAvailable<DataLayout>();
1076
1077  if (!TD)
1078    return false;
1079  BL.reset(new SpecialCaseList(BlacklistFile));
1080  DynamicallyInitializedGlobals.Init(M);
1081
1082  C = &(M.getContext());
1083  LongSize = TD->getPointerSizeInBits();
1084  IntptrTy = Type::getIntNTy(*C, LongSize);
1085
1086  AsanCtorFunction = Function::Create(
1087      FunctionType::get(Type::getVoidTy(*C), false),
1088      GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1089  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1090  // call __asan_init in the module ctor.
1091  IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1092  AsanInitFunction = checkInterfaceFunction(
1093      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1094  AsanInitFunction->setLinkage(Function::ExternalLinkage);
1095  IRB.CreateCall(AsanInitFunction);
1096
1097  Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1098  emitShadowMapping(M, IRB);
1099
1100  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1101  return true;
1102}
1103
1104bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1105  // For each NSObject descendant having a +load method, this method is invoked
1106  // by the ObjC runtime before any of the static constructors is called.
1107  // Therefore we need to instrument such methods with a call to __asan_init
1108  // at the beginning in order to initialize our runtime before any access to
1109  // the shadow memory.
1110  // We cannot just ignore these methods, because they may call other
1111  // instrumented functions.
1112  if (F.getName().find(" load]") != std::string::npos) {
1113    IRBuilder<> IRB(F.begin()->begin());
1114    IRB.CreateCall(AsanInitFunction);
1115    return true;
1116  }
1117  return false;
1118}
1119
1120bool AddressSanitizer::runOnFunction(Function &F) {
1121  if (BL->isIn(F)) return false;
1122  if (&F == AsanCtorFunction) return false;
1123  if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1124  DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1125  initializeCallbacks(*F.getParent());
1126
1127  // If needed, insert __asan_init before checking for SanitizeAddress attr.
1128  maybeInsertAsanInitAtFunctionEntry(F);
1129
1130  if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1131    return false;
1132
1133  if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1134    return false;
1135
1136  // We want to instrument every address only once per basic block (unless there
1137  // are calls between uses).
1138  SmallSet<Value*, 16> TempsToInstrument;
1139  SmallVector<Instruction*, 16> ToInstrument;
1140  SmallVector<Instruction*, 8> NoReturnCalls;
1141  int NumAllocas = 0;
1142  bool IsWrite;
1143
1144  // Fill the set of memory operations to instrument.
1145  for (Function::iterator FI = F.begin(), FE = F.end();
1146       FI != FE; ++FI) {
1147    TempsToInstrument.clear();
1148    int NumInsnsPerBB = 0;
1149    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1150         BI != BE; ++BI) {
1151      if (LooksLikeCodeInBug11395(BI)) return false;
1152      if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1153        if (ClOpt && ClOptSameTemp) {
1154          if (!TempsToInstrument.insert(Addr))
1155            continue;  // We've seen this temp in the current BB.
1156        }
1157      } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1158        // ok, take it.
1159      } else {
1160        if (isa<AllocaInst>(BI))
1161          NumAllocas++;
1162        CallSite CS(BI);
1163        if (CS) {
1164          // A call inside BB.
1165          TempsToInstrument.clear();
1166          if (CS.doesNotReturn())
1167            NoReturnCalls.push_back(CS.getInstruction());
1168        }
1169        continue;
1170      }
1171      ToInstrument.push_back(BI);
1172      NumInsnsPerBB++;
1173      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1174        break;
1175    }
1176  }
1177
1178  Function *UninstrumentedDuplicate = 0;
1179  bool LikelyToInstrument =
1180      !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1181  if (ClKeepUninstrumented && LikelyToInstrument) {
1182    ValueToValueMapTy VMap;
1183    UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1184    UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1185    UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1186    F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1187  }
1188
1189  // Instrument.
1190  int NumInstrumented = 0;
1191  for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1192    Instruction *Inst = ToInstrument[i];
1193    if (ClDebugMin < 0 || ClDebugMax < 0 ||
1194        (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1195      if (isInterestingMemoryAccess(Inst, &IsWrite))
1196        instrumentMop(Inst);
1197      else
1198        instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1199    }
1200    NumInstrumented++;
1201  }
1202
1203  FunctionStackPoisoner FSP(F, *this);
1204  bool ChangedStack = FSP.runOnFunction();
1205
1206  // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1207  // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1208  for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1209    Instruction *CI = NoReturnCalls[i];
1210    IRBuilder<> IRB(CI);
1211    IRB.CreateCall(AsanHandleNoReturnFunc);
1212  }
1213
1214  bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1215  DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1216
1217  if (ClKeepUninstrumented) {
1218    if (!res) {
1219      // No instrumentation is done, no need for the duplicate.
1220      if (UninstrumentedDuplicate)
1221        UninstrumentedDuplicate->eraseFromParent();
1222    } else {
1223      // The function was instrumented. We must have the duplicate.
1224      assert(UninstrumentedDuplicate);
1225      UninstrumentedDuplicate->setSection("NOASAN");
1226      assert(!F.hasSection());
1227      F.setSection("ASAN");
1228    }
1229  }
1230
1231  return res;
1232}
1233
1234static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1235  if (ShadowRedzoneSize == 1) return PoisonByte;
1236  if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1237  if (ShadowRedzoneSize == 4)
1238    return (PoisonByte << 24) + (PoisonByte << 16) +
1239        (PoisonByte << 8) + (PoisonByte);
1240  llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1241}
1242
1243static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1244                                            size_t Size,
1245                                            size_t RZSize,
1246                                            size_t ShadowGranularity,
1247                                            uint8_t Magic) {
1248  for (size_t i = 0; i < RZSize;
1249       i+= ShadowGranularity, Shadow++) {
1250    if (i + ShadowGranularity <= Size) {
1251      *Shadow = 0;  // fully addressable
1252    } else if (i >= Size) {
1253      *Shadow = Magic;  // unaddressable
1254    } else {
1255      *Shadow = Size - i;  // first Size-i bytes are addressable
1256    }
1257  }
1258}
1259
1260// Workaround for bug 11395: we don't want to instrument stack in functions
1261// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1262// FIXME: remove once the bug 11395 is fixed.
1263bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1264  if (LongSize != 32) return false;
1265  CallInst *CI = dyn_cast<CallInst>(I);
1266  if (!CI || !CI->isInlineAsm()) return false;
1267  if (CI->getNumArgOperands() <= 5) return false;
1268  // We have inline assembly with quite a few arguments.
1269  return true;
1270}
1271
1272void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1273  IRBuilder<> IRB(*C);
1274  AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1275      kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1276  AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1277      kAsanStackFreeName, IRB.getVoidTy(),
1278      IntptrTy, IntptrTy, IntptrTy, NULL));
1279  AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1280      kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1281  AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1282      kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1283}
1284
1285void FunctionStackPoisoner::poisonRedZones(
1286  const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1287  bool DoPoison) {
1288  size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1289  assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1290  Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1291  Type *RZPtrTy = PointerType::get(RZTy, 0);
1292
1293  Value *PoisonLeft  = ConstantInt::get(RZTy,
1294    ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1295  Value *PoisonMid   = ConstantInt::get(RZTy,
1296    ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1297  Value *PoisonRight = ConstantInt::get(RZTy,
1298    ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1299
1300  // poison the first red zone.
1301  IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1302
1303  // poison all other red zones.
1304  uint64_t Pos = RedzoneSize();
1305  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1306    AllocaInst *AI = AllocaVec[i];
1307    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1308    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1309    assert(AlignedSize - SizeInBytes < RedzoneSize());
1310    Value *Ptr = NULL;
1311
1312    Pos += AlignedSize;
1313
1314    assert(ShadowBase->getType() == IntptrTy);
1315    if (SizeInBytes < AlignedSize) {
1316      // Poison the partial redzone at right
1317      Ptr = IRB.CreateAdd(
1318          ShadowBase, ConstantInt::get(IntptrTy,
1319                                       (Pos >> Mapping.Scale) - ShadowRZSize));
1320      size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1321      uint32_t Poison = 0;
1322      if (DoPoison) {
1323        PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1324                                        RedzoneSize(),
1325                                        1ULL << Mapping.Scale,
1326                                        kAsanStackPartialRedzoneMagic);
1327        Poison =
1328            ASan.TD->isLittleEndian()
1329                ? support::endian::byte_swap<uint32_t, support::little>(Poison)
1330                : support::endian::byte_swap<uint32_t, support::big>(Poison);
1331      }
1332      Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1333      IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1334    }
1335
1336    // Poison the full redzone at right.
1337    Ptr = IRB.CreateAdd(ShadowBase,
1338                        ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1339    bool LastAlloca = (i == AllocaVec.size() - 1);
1340    Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1341    IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1342
1343    Pos += RedzoneSize();
1344  }
1345}
1346
1347void FunctionStackPoisoner::poisonStack() {
1348  uint64_t LocalStackSize = TotalStackSize +
1349                            (AllocaVec.size() + 1) * RedzoneSize();
1350
1351  bool DoStackMalloc = ASan.CheckUseAfterReturn
1352      && LocalStackSize <= kMaxStackMallocSize;
1353
1354  assert(AllocaVec.size() > 0);
1355  Instruction *InsBefore = AllocaVec[0];
1356  IRBuilder<> IRB(InsBefore);
1357
1358
1359  Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1360  AllocaInst *MyAlloca =
1361      new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1362  if (ClRealignStack && StackAlignment < RedzoneSize())
1363    StackAlignment = RedzoneSize();
1364  MyAlloca->setAlignment(StackAlignment);
1365  assert(MyAlloca->isStaticAlloca());
1366  Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1367  Value *LocalStackBase = OrigStackBase;
1368
1369  if (DoStackMalloc) {
1370    LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1371        ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1372  }
1373
1374  // This string will be parsed by the run-time (DescribeAddressIfStack).
1375  SmallString<2048> StackDescriptionStorage;
1376  raw_svector_ostream StackDescription(StackDescriptionStorage);
1377  StackDescription << AllocaVec.size() << " ";
1378
1379  // Insert poison calls for lifetime intrinsics for alloca.
1380  bool HavePoisonedAllocas = false;
1381  for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1382    const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1383    IntrinsicInst *II = APC.InsBefore;
1384    AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1385    assert(AI);
1386    IRBuilder<> IRB(II);
1387    poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1388    HavePoisonedAllocas |= APC.DoPoison;
1389  }
1390
1391  uint64_t Pos = RedzoneSize();
1392  // Replace Alloca instructions with base+offset.
1393  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1394    AllocaInst *AI = AllocaVec[i];
1395    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1396    StringRef Name = AI->getName();
1397    StackDescription << Pos << " " << SizeInBytes << " "
1398                     << Name.size() << " " << Name << " ";
1399    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1400    assert((AlignedSize % RedzoneSize()) == 0);
1401    Value *NewAllocaPtr = IRB.CreateIntToPtr(
1402            IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1403            AI->getType());
1404    replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1405    AI->replaceAllUsesWith(NewAllocaPtr);
1406    Pos += AlignedSize + RedzoneSize();
1407  }
1408  assert(Pos == LocalStackSize);
1409
1410  // The left-most redzone has enough space for at least 4 pointers.
1411  // Write the Magic value to redzone[0].
1412  Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1413  IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1414                  BasePlus0);
1415  // Write the frame description constant to redzone[1].
1416  Value *BasePlus1 = IRB.CreateIntToPtr(
1417    IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1418    IntptrPtrTy);
1419  GlobalVariable *StackDescriptionGlobal =
1420      createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1421  Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1422                                             IntptrTy);
1423  IRB.CreateStore(Description, BasePlus1);
1424  // Write the PC to redzone[2].
1425  Value *BasePlus2 = IRB.CreateIntToPtr(
1426    IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1427                                                   2 * ASan.LongSize/8)),
1428    IntptrPtrTy);
1429  IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1430
1431  // Poison the stack redzones at the entry.
1432  Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1433  poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1434
1435  // Unpoison the stack before all ret instructions.
1436  for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1437    Instruction *Ret = RetVec[i];
1438    IRBuilder<> IRBRet(Ret);
1439    // Mark the current frame as retired.
1440    IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1441                       BasePlus0);
1442    // Unpoison the stack.
1443    poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1444    if (DoStackMalloc) {
1445      // In use-after-return mode, mark the whole stack frame unaddressable.
1446      IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1447                         ConstantInt::get(IntptrTy, LocalStackSize),
1448                         OrigStackBase);
1449    } else if (HavePoisonedAllocas) {
1450      // If we poisoned some allocas in llvm.lifetime analysis,
1451      // unpoison whole stack frame now.
1452      assert(LocalStackBase == OrigStackBase);
1453      poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1454    }
1455  }
1456
1457  // We are done. Remove the old unused alloca instructions.
1458  for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1459    AllocaVec[i]->eraseFromParent();
1460}
1461
1462void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1463                                         IRBuilder<> IRB, bool DoPoison) {
1464  // For now just insert the call to ASan runtime.
1465  Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1466  Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1467  IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1468                           : AsanUnpoisonStackMemoryFunc,
1469                  AddrArg, SizeArg);
1470}
1471
1472// Handling llvm.lifetime intrinsics for a given %alloca:
1473// (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1474// (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1475//     invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1476//     could be poisoned by previous llvm.lifetime.end instruction, as the
1477//     variable may go in and out of scope several times, e.g. in loops).
1478// (3) if we poisoned at least one %alloca in a function,
1479//     unpoison the whole stack frame at function exit.
1480
1481AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1482  if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1483    // We're intested only in allocas we can handle.
1484    return isInterestingAlloca(*AI) ? AI : 0;
1485  // See if we've already calculated (or started to calculate) alloca for a
1486  // given value.
1487  AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1488  if (I != AllocaForValue.end())
1489    return I->second;
1490  // Store 0 while we're calculating alloca for value V to avoid
1491  // infinite recursion if the value references itself.
1492  AllocaForValue[V] = 0;
1493  AllocaInst *Res = 0;
1494  if (CastInst *CI = dyn_cast<CastInst>(V))
1495    Res = findAllocaForValue(CI->getOperand(0));
1496  else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1497    for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1498      Value *IncValue = PN->getIncomingValue(i);
1499      // Allow self-referencing phi-nodes.
1500      if (IncValue == PN) continue;
1501      AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1502      // AI for incoming values should exist and should all be equal.
1503      if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1504        return 0;
1505      Res = IncValueAI;
1506    }
1507  }
1508  if (Res != 0)
1509    AllocaForValue[V] = Res;
1510  return Res;
1511}
1512