xref: /freebsd/contrib/llvm-project/llvm/lib/Analysis/StackSafetyAnalysis.cpp (revision f3457ed94241be9d4c2c3ab337c9086d5c45c43f) 
1 //===- StackSafetyAnalysis.cpp - Stack memory safety analysis -------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 //===----------------------------------------------------------------------===//
10 
11 #include "llvm/Analysis/StackSafetyAnalysis.h"
12 #include "llvm/ADT/APInt.h"
13 #include "llvm/ADT/SmallPtrSet.h"
14 #include "llvm/ADT/SmallVector.h"
15 #include "llvm/ADT/Statistic.h"
16 #include "llvm/Analysis/ModuleSummaryAnalysis.h"
17 #include "llvm/Analysis/ScalarEvolution.h"
18 #include "llvm/Analysis/StackLifetime.h"
19 #include "llvm/IR/ConstantRange.h"
20 #include "llvm/IR/DerivedTypes.h"
21 #include "llvm/IR/GlobalValue.h"
22 #include "llvm/IR/InstIterator.h"
23 #include "llvm/IR/Instruction.h"
24 #include "llvm/IR/Instructions.h"
25 #include "llvm/IR/IntrinsicInst.h"
26 #include "llvm/IR/ModuleSummaryIndex.h"
27 #include "llvm/InitializePasses.h"
28 #include "llvm/Support/Casting.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/FormatVariadic.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include <algorithm>
33 #include <memory>
34 #include <tuple>
35 
36 using namespace llvm;
37 
38 #define DEBUG_TYPE "stack-safety"
39 
40 STATISTIC(NumAllocaStackSafe, "Number of safe allocas");
41 STATISTIC(NumAllocaTotal, "Number of total allocas");
42 
43 STATISTIC(NumCombinedCalleeLookupTotal,
44           "Number of total callee lookups on combined index.");
45 STATISTIC(NumCombinedCalleeLookupFailed,
46           "Number of failed callee lookups on combined index.");
47 STATISTIC(NumModuleCalleeLookupTotal,
48           "Number of total callee lookups on module index.");
49 STATISTIC(NumModuleCalleeLookupFailed,
50           "Number of failed callee lookups on module index.");
51 STATISTIC(NumCombinedParamAccessesBefore,
52           "Number of total param accesses before generateParamAccessSummary.");
53 STATISTIC(NumCombinedParamAccessesAfter,
54           "Number of total param accesses after generateParamAccessSummary.");
55 STATISTIC(NumCombinedDataFlowNodes,
56           "Number of total nodes in combined index for dataflow processing.");
57 STATISTIC(NumIndexCalleeUnhandled, "Number of index callee which are unhandled.");
58 STATISTIC(NumIndexCalleeMultipleWeak, "Number of index callee non-unique weak.");
59 STATISTIC(NumIndexCalleeMultipleExternal, "Number of index callee non-unique external.");
60 
61 
62 static cl::opt<int> StackSafetyMaxIterations("stack-safety-max-iterations",
63                                              cl::init(20), cl::Hidden);
64 
65 static cl::opt<bool> StackSafetyPrint("stack-safety-print", cl::init(false),
66                                       cl::Hidden);
67 
68 static cl::opt<bool> StackSafetyRun("stack-safety-run", cl::init(false),
69                                     cl::Hidden);
70 
71 namespace {
72 
73 // Check if we should bailout for such ranges.
74 bool isUnsafe(const ConstantRange &R) {
75   return R.isEmptySet() || R.isFullSet() || R.isUpperSignWrapped();
76 }
77 
78 ConstantRange addOverflowNever(const ConstantRange &L, const ConstantRange &R) {
79   assert(!L.isSignWrappedSet());
80   assert(!R.isSignWrappedSet());
81   if (L.signedAddMayOverflow(R) !=
82       ConstantRange::OverflowResult::NeverOverflows)
83     return ConstantRange::getFull(L.getBitWidth());
84   ConstantRange Result = L.add(R);
85   assert(!Result.isSignWrappedSet());
86   return Result;
87 }
88 
89 ConstantRange unionNoWrap(const ConstantRange &L, const ConstantRange &R) {
90   assert(!L.isSignWrappedSet());
91   assert(!R.isSignWrappedSet());
92   auto Result = L.unionWith(R);
93   // Two non-wrapped sets can produce wrapped.
94   if (Result.isSignWrappedSet())
95     Result = ConstantRange::getFull(Result.getBitWidth());
96   return Result;
97 }
98 
99 /// Describes use of address in as a function call argument.
100 template <typename CalleeTy> struct CallInfo {
101   /// Function being called.
102   const CalleeTy *Callee = nullptr;
103   /// Index of argument which pass address.
104   size_t ParamNo = 0;
105 
106   CallInfo(const CalleeTy *Callee, size_t ParamNo)
107       : Callee(Callee), ParamNo(ParamNo) {}
108 
109   struct Less {
110     bool operator()(const CallInfo &L, const CallInfo &R) const {
111       return std::tie(L.ParamNo, L.Callee) < std::tie(R.ParamNo, R.Callee);
112     }
113   };
114 };
115 
116 /// Describe uses of address (alloca or parameter) inside of the function.
117 template <typename CalleeTy> struct UseInfo {
118   // Access range if the address (alloca or parameters).
119   // It is allowed to be empty-set when there are no known accesses.
120   ConstantRange Range;
121   std::set<const Instruction *> UnsafeAccesses;
122 
123   // List of calls which pass address as an argument.
124   // Value is offset range of address from base address (alloca or calling
125   // function argument). Range should never set to empty-set, that is an invalid
126   // access range that can cause empty-set to be propagated with
127   // ConstantRange::add
128   using CallsTy = std::map<CallInfo<CalleeTy>, ConstantRange,
129                            typename CallInfo<CalleeTy>::Less>;
130   CallsTy Calls;
131 
132   UseInfo(unsigned PointerSize) : Range{PointerSize, false} {}
133 
134   void updateRange(const ConstantRange &R) { Range = unionNoWrap(Range, R); }
135   void addRange(const Instruction *I, const ConstantRange &R, bool IsSafe) {
136     if (!IsSafe)
137       UnsafeAccesses.insert(I);
138     updateRange(R);
139   }
140 };
141 
142 template <typename CalleeTy>
143 raw_ostream &operator<<(raw_ostream &OS, const UseInfo<CalleeTy> &U) {
144   OS << U.Range;
145   for (auto &Call : U.Calls)
146     OS << ", "
147        << "@" << Call.first.Callee->getName() << "(arg" << Call.first.ParamNo
148        << ", " << Call.second << ")";
149   return OS;
150 }
151 
152 /// Calculate the allocation size of a given alloca. Returns empty range
153 // in case of confution.
154 ConstantRange getStaticAllocaSizeRange(const AllocaInst &AI) {
155   const DataLayout &DL = AI.getDataLayout();
156   TypeSize TS = DL.getTypeAllocSize(AI.getAllocatedType());
157   unsigned PointerSize = DL.getPointerTypeSizeInBits(AI.getType());
158   // Fallback to empty range for alloca size.
159   ConstantRange R = ConstantRange::getEmpty(PointerSize);
160   if (TS.isScalable())
161     return R;
162   APInt APSize(PointerSize, TS.getFixedValue(), true);
163   if (APSize.isNonPositive())
164     return R;
165   if (AI.isArrayAllocation()) {
166     const auto *C = dyn_cast<ConstantInt>(AI.getArraySize());
167     if (!C)
168       return R;
169     bool Overflow = false;
170     APInt Mul = C->getValue();
171     if (Mul.isNonPositive())
172       return R;
173     Mul = Mul.sextOrTrunc(PointerSize);
174     APSize = APSize.smul_ov(Mul, Overflow);
175     if (Overflow)
176       return R;
177   }
178   R = ConstantRange(APInt::getZero(PointerSize), APSize);
179   assert(!isUnsafe(R));
180   return R;
181 }
182 
183 template <typename CalleeTy> struct FunctionInfo {
184   std::map<const AllocaInst *, UseInfo<CalleeTy>> Allocas;
185   std::map<uint32_t, UseInfo<CalleeTy>> Params;
186   // TODO: describe return value as depending on one or more of its arguments.
187 
188   // StackSafetyDataFlowAnalysis counter stored here for faster access.
189   int UpdateCount = 0;
190 
191   void print(raw_ostream &O, StringRef Name, const Function *F) const {
192     // TODO: Consider different printout format after
193     // StackSafetyDataFlowAnalysis. Calls and parameters are irrelevant then.
194     O << "  @" << Name << ((F && F->isDSOLocal()) ? "" : " dso_preemptable")
195       << ((F && F->isInterposable()) ? " interposable" : "") << "\n";
196 
197     O << "    args uses:\n";
198     for (auto &KV : Params) {
199       O << "      ";
200       if (F)
201         O << F->getArg(KV.first)->getName();
202       else
203         O << formatv("arg{0}", KV.first);
204       O << "[]: " << KV.second << "\n";
205     }
206 
207     O << "    allocas uses:\n";
208     if (F) {
209       for (const auto &I : instructions(F)) {
210         if (const AllocaInst *AI = dyn_cast<AllocaInst>(&I)) {
211           auto &AS = Allocas.find(AI)->second;
212           O << "      " << AI->getName() << "["
213             << getStaticAllocaSizeRange(*AI).getUpper() << "]: " << AS << "\n";
214         }
215       }
216     } else {
217       assert(Allocas.empty());
218     }
219   }
220 };
221 
222 using GVToSSI = std::map<const GlobalValue *, FunctionInfo<GlobalValue>>;
223 
224 } // namespace
225 
226 struct StackSafetyInfo::InfoTy {
227   FunctionInfo<GlobalValue> Info;
228 };
229 
230 struct StackSafetyGlobalInfo::InfoTy {
231   GVToSSI Info;
232   SmallPtrSet<const AllocaInst *, 8> SafeAllocas;
233   std::set<const Instruction *> UnsafeAccesses;
234 };
235 
236 namespace {
237 
238 class StackSafetyLocalAnalysis {
239   Function &F;
240   const DataLayout &DL;
241   ScalarEvolution &SE;
242   unsigned PointerSize = 0;
243 
244   const ConstantRange UnknownRange;
245 
246   /// FIXME: This function is a bandaid, it's only needed
247   /// because this pass doesn't handle address spaces of different pointer
248   /// sizes.
249   ///
250   /// \returns \p Val's SCEV as a pointer of AS zero, or nullptr if it can't be
251   /// converted to AS 0.
252   const SCEV *getSCEVAsPointer(Value *Val);
253 
254   ConstantRange offsetFrom(Value *Addr, Value *Base);
255   ConstantRange getAccessRange(Value *Addr, Value *Base,
256                                const ConstantRange &SizeRange);
257   ConstantRange getAccessRange(Value *Addr, Value *Base, TypeSize Size);
258   ConstantRange getMemIntrinsicAccessRange(const MemIntrinsic *MI, const Use &U,
259                                            Value *Base);
260 
261   void analyzeAllUses(Value *Ptr, UseInfo<GlobalValue> &AS,
262                       const StackLifetime &SL);
263 
264 
265   bool isSafeAccess(const Use &U, AllocaInst *AI, const SCEV *AccessSize);
266   bool isSafeAccess(const Use &U, AllocaInst *AI, Value *V);
267   bool isSafeAccess(const Use &U, AllocaInst *AI, TypeSize AccessSize);
268 
269 public:
270   StackSafetyLocalAnalysis(Function &F, ScalarEvolution &SE)
271       : F(F), DL(F.getDataLayout()), SE(SE),
272         PointerSize(DL.getPointerSizeInBits()),
273         UnknownRange(PointerSize, true) {}
274 
275   // Run the transformation on the associated function.
276   FunctionInfo<GlobalValue> run();
277 };
278 
279 const SCEV *StackSafetyLocalAnalysis::getSCEVAsPointer(Value *Val) {
280   Type *ValTy = Val->getType();
281 
282   // We don't handle targets with multiple address spaces.
283   if (!ValTy->isPointerTy()) {
284     auto *PtrTy = PointerType::getUnqual(SE.getContext());
285     return SE.getTruncateOrZeroExtend(SE.getSCEV(Val), PtrTy);
286   }
287 
288   if (ValTy->getPointerAddressSpace() != 0)
289     return nullptr;
290   return SE.getSCEV(Val);
291 }
292 
293 ConstantRange StackSafetyLocalAnalysis::offsetFrom(Value *Addr, Value *Base) {
294   if (!SE.isSCEVable(Addr->getType()) || !SE.isSCEVable(Base->getType()))
295     return UnknownRange;
296 
297   const SCEV *AddrExp = getSCEVAsPointer(Addr);
298   const SCEV *BaseExp = getSCEVAsPointer(Base);
299   if (!AddrExp || !BaseExp)
300     return UnknownRange;
301 
302   const SCEV *Diff = SE.getMinusSCEV(AddrExp, BaseExp);
303   if (isa<SCEVCouldNotCompute>(Diff))
304     return UnknownRange;
305 
306   ConstantRange Offset = SE.getSignedRange(Diff);
307   if (isUnsafe(Offset))
308     return UnknownRange;
309   return Offset.sextOrTrunc(PointerSize);
310 }
311 
312 ConstantRange
313 StackSafetyLocalAnalysis::getAccessRange(Value *Addr, Value *Base,
314                                          const ConstantRange &SizeRange) {
315   // Zero-size loads and stores do not access memory.
316   if (SizeRange.isEmptySet())
317     return ConstantRange::getEmpty(PointerSize);
318   assert(!isUnsafe(SizeRange));
319 
320   ConstantRange Offsets = offsetFrom(Addr, Base);
321   if (isUnsafe(Offsets))
322     return UnknownRange;
323 
324   Offsets = addOverflowNever(Offsets, SizeRange);
325   if (isUnsafe(Offsets))
326     return UnknownRange;
327   return Offsets;
328 }
329 
330 ConstantRange StackSafetyLocalAnalysis::getAccessRange(Value *Addr, Value *Base,
331                                                        TypeSize Size) {
332   if (Size.isScalable())
333     return UnknownRange;
334   APInt APSize(PointerSize, Size.getFixedValue(), true);
335   if (APSize.isNegative())
336     return UnknownRange;
337   return getAccessRange(Addr, Base,
338                         ConstantRange(APInt::getZero(PointerSize), APSize));
339 }
340 
341 ConstantRange StackSafetyLocalAnalysis::getMemIntrinsicAccessRange(
342     const MemIntrinsic *MI, const Use &U, Value *Base) {
343   if (const auto *MTI = dyn_cast<MemTransferInst>(MI)) {
344     if (MTI->getRawSource() != U && MTI->getRawDest() != U)
345       return ConstantRange::getEmpty(PointerSize);
346   } else {
347     if (MI->getRawDest() != U)
348       return ConstantRange::getEmpty(PointerSize);
349   }
350 
351   auto *CalculationTy = IntegerType::getIntNTy(SE.getContext(), PointerSize);
352   if (!SE.isSCEVable(MI->getLength()->getType()))
353     return UnknownRange;
354 
355   const SCEV *Expr =
356       SE.getTruncateOrZeroExtend(SE.getSCEV(MI->getLength()), CalculationTy);
357   ConstantRange Sizes = SE.getSignedRange(Expr);
358   if (!Sizes.getUpper().isStrictlyPositive() || isUnsafe(Sizes))
359     return UnknownRange;
360   Sizes = Sizes.sextOrTrunc(PointerSize);
361   ConstantRange SizeRange(APInt::getZero(PointerSize), Sizes.getUpper() - 1);
362   return getAccessRange(U, Base, SizeRange);
363 }
364 
365 bool StackSafetyLocalAnalysis::isSafeAccess(const Use &U, AllocaInst *AI,
366                                             Value *V) {
367   return isSafeAccess(U, AI, SE.getSCEV(V));
368 }
369 
370 bool StackSafetyLocalAnalysis::isSafeAccess(const Use &U, AllocaInst *AI,
371                                             TypeSize TS) {
372   if (TS.isScalable())
373     return false;
374   auto *CalculationTy = IntegerType::getIntNTy(SE.getContext(), PointerSize);
375   const SCEV *SV = SE.getConstant(CalculationTy, TS.getFixedValue());
376   return isSafeAccess(U, AI, SV);
377 }
378 
379 bool StackSafetyLocalAnalysis::isSafeAccess(const Use &U, AllocaInst *AI,
380                                             const SCEV *AccessSize) {
381 
382   if (!AI)
383     return true; // This only judges whether it is a safe *stack* access.
384   if (isa<SCEVCouldNotCompute>(AccessSize))
385     return false;
386 
387   const auto *I = cast<Instruction>(U.getUser());
388 
389   const SCEV *AddrExp = getSCEVAsPointer(U.get());
390   const SCEV *BaseExp = getSCEVAsPointer(AI);
391   if (!AddrExp || !BaseExp)
392     return false;
393 
394   const SCEV *Diff = SE.getMinusSCEV(AddrExp, BaseExp);
395   if (isa<SCEVCouldNotCompute>(Diff))
396     return false;
397 
398   auto Size = getStaticAllocaSizeRange(*AI);
399 
400   auto *CalculationTy = IntegerType::getIntNTy(SE.getContext(), PointerSize);
401   auto ToDiffTy = [&](const SCEV *V) {
402     return SE.getTruncateOrZeroExtend(V, CalculationTy);
403   };
404   const SCEV *Min = ToDiffTy(SE.getConstant(Size.getLower()));
405   const SCEV *Max = SE.getMinusSCEV(ToDiffTy(SE.getConstant(Size.getUpper())),
406                                     ToDiffTy(AccessSize));
407   return SE.evaluatePredicateAt(ICmpInst::Predicate::ICMP_SGE, Diff, Min, I)
408              .value_or(false) &&
409          SE.evaluatePredicateAt(ICmpInst::Predicate::ICMP_SLE, Diff, Max, I)
410              .value_or(false);
411 }
412 
413 /// The function analyzes all local uses of Ptr (alloca or argument) and
414 /// calculates local access range and all function calls where it was used.
415 void StackSafetyLocalAnalysis::analyzeAllUses(Value *Ptr,
416                                               UseInfo<GlobalValue> &US,
417                                               const StackLifetime &SL) {
418   SmallPtrSet<const Value *, 16> Visited;
419   SmallVector<const Value *, 8> WorkList;
420   WorkList.push_back(Ptr);
421   AllocaInst *AI = dyn_cast<AllocaInst>(Ptr);
422 
423   // A DFS search through all uses of the alloca in bitcasts/PHI/GEPs/etc.
424   while (!WorkList.empty()) {
425     const Value *V = WorkList.pop_back_val();
426     for (const Use &UI : V->uses()) {
427       const auto *I = cast<Instruction>(UI.getUser());
428       if (!SL.isReachable(I))
429         continue;
430 
431       assert(V == UI.get());
432 
433       auto RecordStore = [&](const Value* StoredVal) {
434         if (V == StoredVal) {
435           // Stored the pointer - conservatively assume it may be unsafe.
436           US.addRange(I, UnknownRange, /*IsSafe=*/false);
437           return;
438         }
439         if (AI && !SL.isAliveAfter(AI, I)) {
440           US.addRange(I, UnknownRange, /*IsSafe=*/false);
441           return;
442         }
443         auto TypeSize = DL.getTypeStoreSize(StoredVal->getType());
444         auto AccessRange = getAccessRange(UI, Ptr, TypeSize);
445         bool Safe = isSafeAccess(UI, AI, TypeSize);
446         US.addRange(I, AccessRange, Safe);
447         return;
448       };
449 
450       switch (I->getOpcode()) {
451       case Instruction::Load: {
452         if (AI && !SL.isAliveAfter(AI, I)) {
453           US.addRange(I, UnknownRange, /*IsSafe=*/false);
454           break;
455         }
456         auto TypeSize = DL.getTypeStoreSize(I->getType());
457         auto AccessRange = getAccessRange(UI, Ptr, TypeSize);
458         bool Safe = isSafeAccess(UI, AI, TypeSize);
459         US.addRange(I, AccessRange, Safe);
460         break;
461       }
462 
463       case Instruction::VAArg:
464         // "va-arg" from a pointer is safe.
465         break;
466       case Instruction::Store:
467         RecordStore(cast<StoreInst>(I)->getValueOperand());
468         break;
469       case Instruction::AtomicCmpXchg:
470         RecordStore(cast<AtomicCmpXchgInst>(I)->getNewValOperand());
471         break;
472       case Instruction::AtomicRMW:
473         RecordStore(cast<AtomicRMWInst>(I)->getValOperand());
474         break;
475 
476       case Instruction::Ret:
477         // Information leak.
478         // FIXME: Process parameters correctly. This is a leak only if we return
479         // alloca.
480         US.addRange(I, UnknownRange, /*IsSafe=*/false);
481         break;
482 
483       case Instruction::Call:
484       case Instruction::Invoke: {
485         if (I->isLifetimeStartOrEnd())
486           break;
487 
488         if (AI && !SL.isAliveAfter(AI, I)) {
489           US.addRange(I, UnknownRange, /*IsSafe=*/false);
490           break;
491         }
492         if (const MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I)) {
493           auto AccessRange = getMemIntrinsicAccessRange(MI, UI, Ptr);
494           bool Safe = false;
495           if (const auto *MTI = dyn_cast<MemTransferInst>(MI)) {
496             if (MTI->getRawSource() != UI && MTI->getRawDest() != UI)
497               Safe = true;
498           } else if (MI->getRawDest() != UI) {
499             Safe = true;
500           }
501           Safe = Safe || isSafeAccess(UI, AI, MI->getLength());
502           US.addRange(I, AccessRange, Safe);
503           break;
504         }
505 
506         const auto &CB = cast<CallBase>(*I);
507         if (CB.getReturnedArgOperand() == V) {
508           if (Visited.insert(I).second)
509             WorkList.push_back(cast<const Instruction>(I));
510         }
511 
512         if (!CB.isArgOperand(&UI)) {
513           US.addRange(I, UnknownRange, /*IsSafe=*/false);
514           break;
515         }
516 
517         unsigned ArgNo = CB.getArgOperandNo(&UI);
518         if (CB.isByValArgument(ArgNo)) {
519           auto TypeSize = DL.getTypeStoreSize(CB.getParamByValType(ArgNo));
520           auto AccessRange = getAccessRange(UI, Ptr, TypeSize);
521           bool Safe = isSafeAccess(UI, AI, TypeSize);
522           US.addRange(I, AccessRange, Safe);
523           break;
524         }
525 
526         // FIXME: consult devirt?
527         // Do not follow aliases, otherwise we could inadvertently follow
528         // dso_preemptable aliases or aliases with interposable linkage.
529         const GlobalValue *Callee =
530             dyn_cast<GlobalValue>(CB.getCalledOperand()->stripPointerCasts());
531         if (!Callee || isa<GlobalIFunc>(Callee)) {
532           US.addRange(I, UnknownRange, /*IsSafe=*/false);
533           break;
534         }
535 
536         assert(isa<Function>(Callee) || isa<GlobalAlias>(Callee));
537         ConstantRange Offsets = offsetFrom(UI, Ptr);
538         auto Insert =
539             US.Calls.emplace(CallInfo<GlobalValue>(Callee, ArgNo), Offsets);
540         if (!Insert.second)
541           Insert.first->second = Insert.first->second.unionWith(Offsets);
542         break;
543       }
544 
545       default:
546         if (Visited.insert(I).second)
547           WorkList.push_back(cast<const Instruction>(I));
548       }
549     }
550   }
551 }
552 
553 FunctionInfo<GlobalValue> StackSafetyLocalAnalysis::run() {
554   FunctionInfo<GlobalValue> Info;
555   assert(!F.isDeclaration() &&
556          "Can't run StackSafety on a function declaration");
557 
558   LLVM_DEBUG(dbgs() << "[StackSafety] " << F.getName() << "\n");
559 
560   SmallVector<AllocaInst *, 64> Allocas;
561   for (auto &I : instructions(F))
562     if (auto *AI = dyn_cast<AllocaInst>(&I))
563       Allocas.push_back(AI);
564   StackLifetime SL(F, Allocas, StackLifetime::LivenessType::Must);
565   SL.run();
566 
567   for (auto *AI : Allocas) {
568     auto &UI = Info.Allocas.emplace(AI, PointerSize).first->second;
569     analyzeAllUses(AI, UI, SL);
570   }
571 
572   for (Argument &A : F.args()) {
573     // Non pointers and bypass arguments are not going to be used in any global
574     // processing.
575     if (A.getType()->isPointerTy() && !A.hasByValAttr()) {
576       auto &UI = Info.Params.emplace(A.getArgNo(), PointerSize).first->second;
577       analyzeAllUses(&A, UI, SL);
578     }
579   }
580 
581   LLVM_DEBUG(Info.print(dbgs(), F.getName(), &F));
582   LLVM_DEBUG(dbgs() << "\n[StackSafety] done\n");
583   return Info;
584 }
585 
586 template <typename CalleeTy> class StackSafetyDataFlowAnalysis {
587   using FunctionMap = std::map<const CalleeTy *, FunctionInfo<CalleeTy>>;
588 
589   FunctionMap Functions;
590   const ConstantRange UnknownRange;
591 
592   // Callee-to-Caller multimap.
593   DenseMap<const CalleeTy *, SmallVector<const CalleeTy *, 4>> Callers;
594   SetVector<const CalleeTy *> WorkList;
595 
596   bool updateOneUse(UseInfo<CalleeTy> &US, bool UpdateToFullSet);
597   void updateOneNode(const CalleeTy *Callee, FunctionInfo<CalleeTy> &FS);
598   void updateOneNode(const CalleeTy *Callee) {
599     updateOneNode(Callee, Functions.find(Callee)->second);
600   }
601   void updateAllNodes() {
602     for (auto &F : Functions)
603       updateOneNode(F.first, F.second);
604   }
605   void runDataFlow();
606 #ifndef NDEBUG
607   void verifyFixedPoint();
608 #endif
609 
610 public:
611   StackSafetyDataFlowAnalysis(uint32_t PointerBitWidth, FunctionMap Functions)
612       : Functions(std::move(Functions)),
613         UnknownRange(ConstantRange::getFull(PointerBitWidth)) {}
614 
615   const FunctionMap &run();
616 
617   ConstantRange getArgumentAccessRange(const CalleeTy *Callee, unsigned ParamNo,
618                                        const ConstantRange &Offsets) const;
619 };
620 
621 template <typename CalleeTy>
622 ConstantRange StackSafetyDataFlowAnalysis<CalleeTy>::getArgumentAccessRange(
623     const CalleeTy *Callee, unsigned ParamNo,
624     const ConstantRange &Offsets) const {
625   auto FnIt = Functions.find(Callee);
626   // Unknown callee (outside of LTO domain or an indirect call).
627   if (FnIt == Functions.end())
628     return UnknownRange;
629   auto &FS = FnIt->second;
630   auto ParamIt = FS.Params.find(ParamNo);
631   if (ParamIt == FS.Params.end())
632     return UnknownRange;
633   auto &Access = ParamIt->second.Range;
634   if (Access.isEmptySet())
635     return Access;
636   if (Access.isFullSet())
637     return UnknownRange;
638   return addOverflowNever(Access, Offsets);
639 }
640 
641 template <typename CalleeTy>
642 bool StackSafetyDataFlowAnalysis<CalleeTy>::updateOneUse(UseInfo<CalleeTy> &US,
643                                                          bool UpdateToFullSet) {
644   bool Changed = false;
645   for (auto &KV : US.Calls) {
646     assert(!KV.second.isEmptySet() &&
647            "Param range can't be empty-set, invalid offset range");
648 
649     ConstantRange CalleeRange =
650         getArgumentAccessRange(KV.first.Callee, KV.first.ParamNo, KV.second);
651     if (!US.Range.contains(CalleeRange)) {
652       Changed = true;
653       if (UpdateToFullSet)
654         US.Range = UnknownRange;
655       else
656         US.updateRange(CalleeRange);
657     }
658   }
659   return Changed;
660 }
661 
662 template <typename CalleeTy>
663 void StackSafetyDataFlowAnalysis<CalleeTy>::updateOneNode(
664     const CalleeTy *Callee, FunctionInfo<CalleeTy> &FS) {
665   bool UpdateToFullSet = FS.UpdateCount > StackSafetyMaxIterations;
666   bool Changed = false;
667   for (auto &KV : FS.Params)
668     Changed |= updateOneUse(KV.second, UpdateToFullSet);
669 
670   if (Changed) {
671     LLVM_DEBUG(dbgs() << "=== update [" << FS.UpdateCount
672                       << (UpdateToFullSet ? ", full-set" : "") << "] " << &FS
673                       << "\n");
674     // Callers of this function may need updating.
675     for (auto &CallerID : Callers[Callee])
676       WorkList.insert(CallerID);
677 
678     ++FS.UpdateCount;
679   }
680 }
681 
682 template <typename CalleeTy>
683 void StackSafetyDataFlowAnalysis<CalleeTy>::runDataFlow() {
684   SmallVector<const CalleeTy *, 16> Callees;
685   for (auto &F : Functions) {
686     Callees.clear();
687     auto &FS = F.second;
688     for (auto &KV : FS.Params)
689       for (auto &CS : KV.second.Calls)
690         Callees.push_back(CS.first.Callee);
691 
692     llvm::sort(Callees);
693     Callees.erase(llvm::unique(Callees), Callees.end());
694 
695     for (auto &Callee : Callees)
696       Callers[Callee].push_back(F.first);
697   }
698 
699   updateAllNodes();
700 
701   while (!WorkList.empty()) {
702     const CalleeTy *Callee = WorkList.pop_back_val();
703     updateOneNode(Callee);
704   }
705 }
706 
707 #ifndef NDEBUG
708 template <typename CalleeTy>
709 void StackSafetyDataFlowAnalysis<CalleeTy>::verifyFixedPoint() {
710   WorkList.clear();
711   updateAllNodes();
712   assert(WorkList.empty());
713 }
714 #endif
715 
716 template <typename CalleeTy>
717 const typename StackSafetyDataFlowAnalysis<CalleeTy>::FunctionMap &
718 StackSafetyDataFlowAnalysis<CalleeTy>::run() {
719   runDataFlow();
720   LLVM_DEBUG(verifyFixedPoint());
721   return Functions;
722 }
723 
724 FunctionSummary *findCalleeFunctionSummary(ValueInfo VI, StringRef ModuleId) {
725   if (!VI)
726     return nullptr;
727   auto SummaryList = VI.getSummaryList();
728   GlobalValueSummary* S = nullptr;
729   for (const auto& GVS : SummaryList) {
730     if (!GVS->isLive())
731       continue;
732     if (const AliasSummary *AS = dyn_cast<AliasSummary>(GVS.get()))
733       if (!AS->hasAliasee())
734         continue;
735     if (!isa<FunctionSummary>(GVS->getBaseObject()))
736       continue;
737     if (GlobalValue::isLocalLinkage(GVS->linkage())) {
738       if (GVS->modulePath() == ModuleId) {
739         S = GVS.get();
740         break;
741       }
742     } else if (GlobalValue::isExternalLinkage(GVS->linkage())) {
743       if (S) {
744         ++NumIndexCalleeMultipleExternal;
745         return nullptr;
746       }
747       S = GVS.get();
748     } else if (GlobalValue::isWeakLinkage(GVS->linkage())) {
749       if (S) {
750         ++NumIndexCalleeMultipleWeak;
751         return nullptr;
752       }
753       S = GVS.get();
754     } else if (GlobalValue::isAvailableExternallyLinkage(GVS->linkage()) ||
755                GlobalValue::isLinkOnceLinkage(GVS->linkage())) {
756       if (SummaryList.size() == 1)
757         S = GVS.get();
758       // According thinLTOResolvePrevailingGUID these are unlikely prevailing.
759     } else {
760       ++NumIndexCalleeUnhandled;
761     }
762   };
763   while (S) {
764     if (!S->isLive() || !S->isDSOLocal())
765       return nullptr;
766     if (FunctionSummary *FS = dyn_cast<FunctionSummary>(S))
767       return FS;
768     AliasSummary *AS = dyn_cast<AliasSummary>(S);
769     if (!AS || !AS->hasAliasee())
770       return nullptr;
771     S = AS->getBaseObject();
772     if (S == AS)
773       return nullptr;
774   }
775   return nullptr;
776 }
777 
778 const Function *findCalleeInModule(const GlobalValue *GV) {
779   while (GV) {
780     if (GV->isDeclaration() || GV->isInterposable() || !GV->isDSOLocal())
781       return nullptr;
782     if (const Function *F = dyn_cast<Function>(GV))
783       return F;
784     const GlobalAlias *A = dyn_cast<GlobalAlias>(GV);
785     if (!A)
786       return nullptr;
787     GV = A->getAliaseeObject();
788     if (GV == A)
789       return nullptr;
790   }
791   return nullptr;
792 }
793 
794 const ConstantRange *findParamAccess(const FunctionSummary &FS,
795                                      uint32_t ParamNo) {
796   assert(FS.isLive());
797   assert(FS.isDSOLocal());
798   for (const auto &PS : FS.paramAccesses())
799     if (ParamNo == PS.ParamNo)
800       return &PS.Use;
801   return nullptr;
802 }
803 
804 void resolveAllCalls(UseInfo<GlobalValue> &Use,
805                      const ModuleSummaryIndex *Index) {
806   ConstantRange FullSet(Use.Range.getBitWidth(), true);
807   // Move Use.Calls to a temp storage and repopulate - don't use std::move as it
808   // leaves Use.Calls in an undefined state.
809   UseInfo<GlobalValue>::CallsTy TmpCalls;
810   std::swap(TmpCalls, Use.Calls);
811   for (const auto &C : TmpCalls) {
812     const Function *F = findCalleeInModule(C.first.Callee);
813     if (F) {
814       Use.Calls.emplace(CallInfo<GlobalValue>(F, C.first.ParamNo), C.second);
815       continue;
816     }
817 
818     if (!Index)
819       return Use.updateRange(FullSet);
820     FunctionSummary *FS =
821         findCalleeFunctionSummary(Index->getValueInfo(C.first.Callee->getGUID()),
822                                   C.first.Callee->getParent()->getModuleIdentifier());
823     ++NumModuleCalleeLookupTotal;
824     if (!FS) {
825       ++NumModuleCalleeLookupFailed;
826       return Use.updateRange(FullSet);
827     }
828     const ConstantRange *Found = findParamAccess(*FS, C.first.ParamNo);
829     if (!Found || Found->isFullSet())
830       return Use.updateRange(FullSet);
831     ConstantRange Access = Found->sextOrTrunc(Use.Range.getBitWidth());
832     if (!Access.isEmptySet())
833       Use.updateRange(addOverflowNever(Access, C.second));
834   }
835 }
836 
837 GVToSSI createGlobalStackSafetyInfo(
838     std::map<const GlobalValue *, FunctionInfo<GlobalValue>> Functions,
839     const ModuleSummaryIndex *Index) {
840   GVToSSI SSI;
841   if (Functions.empty())
842     return SSI;
843 
844   // FIXME: Simplify printing and remove copying here.
845   auto Copy = Functions;
846 
847   for (auto &FnKV : Copy)
848     for (auto &KV : FnKV.second.Params) {
849       resolveAllCalls(KV.second, Index);
850       if (KV.second.Range.isFullSet())
851         KV.second.Calls.clear();
852     }
853 
854   uint32_t PointerSize =
855       Copy.begin()->first->getDataLayout().getPointerSizeInBits();
856   StackSafetyDataFlowAnalysis<GlobalValue> SSDFA(PointerSize, std::move(Copy));
857 
858   for (const auto &F : SSDFA.run()) {
859     auto FI = F.second;
860     auto &SrcF = Functions[F.first];
861     for (auto &KV : FI.Allocas) {
862       auto &A = KV.second;
863       resolveAllCalls(A, Index);
864       for (auto &C : A.Calls) {
865         A.updateRange(SSDFA.getArgumentAccessRange(C.first.Callee,
866                                                    C.first.ParamNo, C.second));
867       }
868       // FIXME: This is needed only to preserve calls in print() results.
869       A.Calls = SrcF.Allocas.find(KV.first)->second.Calls;
870     }
871     for (auto &KV : FI.Params) {
872       auto &P = KV.second;
873       P.Calls = SrcF.Params.find(KV.first)->second.Calls;
874     }
875     SSI[F.first] = std::move(FI);
876   }
877 
878   return SSI;
879 }
880 
881 } // end anonymous namespace
882 
883 StackSafetyInfo::StackSafetyInfo() = default;
884 
885 StackSafetyInfo::StackSafetyInfo(Function *F,
886                                  std::function<ScalarEvolution &()> GetSE)
887     : F(F), GetSE(GetSE) {}
888 
889 StackSafetyInfo::StackSafetyInfo(StackSafetyInfo &&) = default;
890 
891 StackSafetyInfo &StackSafetyInfo::operator=(StackSafetyInfo &&) = default;
892 
893 StackSafetyInfo::~StackSafetyInfo() = default;
894 
895 const StackSafetyInfo::InfoTy &StackSafetyInfo::getInfo() const {
896   if (!Info) {
897     StackSafetyLocalAnalysis SSLA(*F, GetSE());
898     Info.reset(new InfoTy{SSLA.run()});
899   }
900   return *Info;
901 }
902 
903 void StackSafetyInfo::print(raw_ostream &O) const {
904   getInfo().Info.print(O, F->getName(), dyn_cast<Function>(F));
905   O << "\n";
906 }
907 
908 const StackSafetyGlobalInfo::InfoTy &StackSafetyGlobalInfo::getInfo() const {
909   if (!Info) {
910     std::map<const GlobalValue *, FunctionInfo<GlobalValue>> Functions;
911     for (auto &F : M->functions()) {
912       if (!F.isDeclaration()) {
913         auto FI = GetSSI(F).getInfo().Info;
914         Functions.emplace(&F, std::move(FI));
915       }
916     }
917     Info.reset(new InfoTy{
918         createGlobalStackSafetyInfo(std::move(Functions), Index), {}, {}});
919 
920     for (auto &FnKV : Info->Info) {
921       for (auto &KV : FnKV.second.Allocas) {
922         ++NumAllocaTotal;
923         const AllocaInst *AI = KV.first;
924         auto AIRange = getStaticAllocaSizeRange(*AI);
925         if (AIRange.contains(KV.second.Range)) {
926           Info->SafeAllocas.insert(AI);
927           ++NumAllocaStackSafe;
928         }
929         Info->UnsafeAccesses.insert(KV.second.UnsafeAccesses.begin(),
930                                     KV.second.UnsafeAccesses.end());
931       }
932     }
933 
934     if (StackSafetyPrint)
935       print(errs());
936   }
937   return *Info;
938 }
939 
940 std::vector<FunctionSummary::ParamAccess>
941 StackSafetyInfo::getParamAccesses(ModuleSummaryIndex &Index) const {
942   // Implementation transforms internal representation of parameter information
943   // into FunctionSummary format.
944   std::vector<FunctionSummary::ParamAccess> ParamAccesses;
945   for (const auto &KV : getInfo().Info.Params) {
946     auto &PS = KV.second;
947     // Parameter accessed by any or unknown offset, represented as FullSet by
948     // StackSafety, is handled as the parameter for which we have no
949     // StackSafety info at all. So drop it to reduce summary size.
950     if (PS.Range.isFullSet())
951       continue;
952 
953     ParamAccesses.emplace_back(KV.first, PS.Range);
954     FunctionSummary::ParamAccess &Param = ParamAccesses.back();
955 
956     Param.Calls.reserve(PS.Calls.size());
957     for (const auto &C : PS.Calls) {
958       // Parameter forwarded into another function by any or unknown offset
959       // will make ParamAccess::Range as FullSet anyway. So we can drop the
960       // entire parameter like we did above.
961       // TODO(vitalybuka): Return already filtered parameters from getInfo().
962       if (C.second.isFullSet()) {
963         ParamAccesses.pop_back();
964         break;
965       }
966       Param.Calls.emplace_back(C.first.ParamNo,
967                                Index.getOrInsertValueInfo(C.first.Callee),
968                                C.second);
969     }
970   }
971   for (FunctionSummary::ParamAccess &Param : ParamAccesses) {
972     sort(Param.Calls, [](const FunctionSummary::ParamAccess::Call &L,
973                          const FunctionSummary::ParamAccess::Call &R) {
974       return std::tie(L.ParamNo, L.Callee) < std::tie(R.ParamNo, R.Callee);
975     });
976   }
977   return ParamAccesses;
978 }
979 
980 StackSafetyGlobalInfo::StackSafetyGlobalInfo() = default;
981 
982 StackSafetyGlobalInfo::StackSafetyGlobalInfo(
983     Module *M, std::function<const StackSafetyInfo &(Function &F)> GetSSI,
984     const ModuleSummaryIndex *Index)
985     : M(M), GetSSI(GetSSI), Index(Index) {
986   if (StackSafetyRun)
987     getInfo();
988 }
989 
990 StackSafetyGlobalInfo::StackSafetyGlobalInfo(StackSafetyGlobalInfo &&) =
991     default;
992 
993 StackSafetyGlobalInfo &
994 StackSafetyGlobalInfo::operator=(StackSafetyGlobalInfo &&) = default;
995 
996 StackSafetyGlobalInfo::~StackSafetyGlobalInfo() = default;
997 
998 bool StackSafetyGlobalInfo::isSafe(const AllocaInst &AI) const {
999   const auto &Info = getInfo();
1000   return Info.SafeAllocas.count(&AI);
1001 }
1002 
1003 bool StackSafetyGlobalInfo::stackAccessIsSafe(const Instruction &I) const {
1004   const auto &Info = getInfo();
1005   return Info.UnsafeAccesses.find(&I) == Info.UnsafeAccesses.end();
1006 }
1007 
1008 void StackSafetyGlobalInfo::print(raw_ostream &O) const {
1009   auto &SSI = getInfo().Info;
1010   if (SSI.empty())
1011     return;
1012   const Module &M = *SSI.begin()->first->getParent();
1013   for (const auto &F : M.functions()) {
1014     if (!F.isDeclaration()) {
1015       SSI.find(&F)->second.print(O, F.getName(), &F);
1016       O << "    safe accesses:"
1017         << "\n";
1018       for (const auto &I : instructions(F)) {
1019         const CallInst *Call = dyn_cast<CallInst>(&I);
1020         if ((isa<StoreInst>(I) || isa<LoadInst>(I) || isa<MemIntrinsic>(I) ||
1021              isa<AtomicCmpXchgInst>(I) || isa<AtomicRMWInst>(I) ||
1022              (Call && Call->hasByValArgument())) &&
1023             stackAccessIsSafe(I)) {
1024           O << "     " << I << "\n";
1025         }
1026       }
1027       O << "\n";
1028     }
1029   }
1030 }
1031 
1032 LLVM_DUMP_METHOD void StackSafetyGlobalInfo::dump() const { print(dbgs()); }
1033 
1034 AnalysisKey StackSafetyAnalysis::Key;
1035 
1036 StackSafetyInfo StackSafetyAnalysis::run(Function &F,
1037                                          FunctionAnalysisManager &AM) {
1038   return StackSafetyInfo(&F, [&AM, &F]() -> ScalarEvolution & {
1039     return AM.getResult<ScalarEvolutionAnalysis>(F);
1040   });
1041 }
1042 
1043 PreservedAnalyses StackSafetyPrinterPass::run(Function &F,
1044                                               FunctionAnalysisManager &AM) {
1045   OS << "'Stack Safety Local Analysis' for function '" << F.getName() << "'\n";
1046   AM.getResult<StackSafetyAnalysis>(F).print(OS);
1047   return PreservedAnalyses::all();
1048 }
1049 
1050 char StackSafetyInfoWrapperPass::ID = 0;
1051 
1052 StackSafetyInfoWrapperPass::StackSafetyInfoWrapperPass() : FunctionPass(ID) {
1053   initializeStackSafetyInfoWrapperPassPass(*PassRegistry::getPassRegistry());
1054 }
1055 
1056 void StackSafetyInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
1057   AU.addRequiredTransitive<ScalarEvolutionWrapperPass>();
1058   AU.setPreservesAll();
1059 }
1060 
1061 void StackSafetyInfoWrapperPass::print(raw_ostream &O, const Module *M) const {
1062   SSI.print(O);
1063 }
1064 
1065 bool StackSafetyInfoWrapperPass::runOnFunction(Function &F) {
1066   auto *SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
1067   SSI = {&F, [SE]() -> ScalarEvolution & { return *SE; }};
1068   return false;
1069 }
1070 
1071 AnalysisKey StackSafetyGlobalAnalysis::Key;
1072 
1073 StackSafetyGlobalInfo
1074 StackSafetyGlobalAnalysis::run(Module &M, ModuleAnalysisManager &AM) {
1075   // FIXME: Lookup Module Summary.
1076   FunctionAnalysisManager &FAM =
1077       AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
1078   return {&M,
1079           [&FAM](Function &F) -> const StackSafetyInfo & {
1080             return FAM.getResult<StackSafetyAnalysis>(F);
1081           },
1082           nullptr};
1083 }
1084 
1085 PreservedAnalyses StackSafetyGlobalPrinterPass::run(Module &M,
1086                                                     ModuleAnalysisManager &AM) {
1087   OS << "'Stack Safety Analysis' for module '" << M.getName() << "'\n";
1088   AM.getResult<StackSafetyGlobalAnalysis>(M).print(OS);
1089   return PreservedAnalyses::all();
1090 }
1091 
1092 char StackSafetyGlobalInfoWrapperPass::ID = 0;
1093 
1094 StackSafetyGlobalInfoWrapperPass::StackSafetyGlobalInfoWrapperPass()
1095     : ModulePass(ID) {
1096   initializeStackSafetyGlobalInfoWrapperPassPass(
1097       *PassRegistry::getPassRegistry());
1098 }
1099 
1100 StackSafetyGlobalInfoWrapperPass::~StackSafetyGlobalInfoWrapperPass() = default;
1101 
1102 void StackSafetyGlobalInfoWrapperPass::print(raw_ostream &O,
1103                                              const Module *M) const {
1104   SSGI.print(O);
1105 }
1106 
1107 void StackSafetyGlobalInfoWrapperPass::getAnalysisUsage(
1108     AnalysisUsage &AU) const {
1109   AU.setPreservesAll();
1110   AU.addRequired<StackSafetyInfoWrapperPass>();
1111 }
1112 
1113 bool StackSafetyGlobalInfoWrapperPass::runOnModule(Module &M) {
1114   const ModuleSummaryIndex *ImportSummary = nullptr;
1115   if (auto *IndexWrapperPass =
1116           getAnalysisIfAvailable<ImmutableModuleSummaryIndexWrapperPass>())
1117     ImportSummary = IndexWrapperPass->getIndex();
1118 
1119   SSGI = {&M,
1120           [this](Function &F) -> const StackSafetyInfo & {
1121             return getAnalysis<StackSafetyInfoWrapperPass>(F).getResult();
1122           },
1123           ImportSummary};
1124   return false;
1125 }
1126 
1127 bool llvm::needsParamAccessSummary(const Module &M) {
1128   if (StackSafetyRun)
1129     return true;
1130   for (const auto &F : M.functions())
1131     if (F.hasFnAttribute(Attribute::SanitizeMemTag))
1132       return true;
1133   return false;
1134 }
1135 
1136 void llvm::generateParamAccessSummary(ModuleSummaryIndex &Index) {
1137   if (!Index.hasParamAccess())
1138     return;
1139   const ConstantRange FullSet(FunctionSummary::ParamAccess::RangeWidth, true);
1140 
1141   auto CountParamAccesses = [&](auto &Stat) {
1142     if (!AreStatisticsEnabled())
1143       return;
1144     for (auto &GVS : Index)
1145       for (auto &GV : GVS.second.SummaryList)
1146         if (FunctionSummary *FS = dyn_cast<FunctionSummary>(GV.get()))
1147           Stat += FS->paramAccesses().size();
1148   };
1149 
1150   CountParamAccesses(NumCombinedParamAccessesBefore);
1151 
1152   std::map<const FunctionSummary *, FunctionInfo<FunctionSummary>> Functions;
1153 
1154   // Convert the ModuleSummaryIndex to a FunctionMap
1155   for (auto &GVS : Index) {
1156     for (auto &GV : GVS.second.SummaryList) {
1157       FunctionSummary *FS = dyn_cast<FunctionSummary>(GV.get());
1158       if (!FS || FS->paramAccesses().empty())
1159         continue;
1160       if (FS->isLive() && FS->isDSOLocal()) {
1161         FunctionInfo<FunctionSummary> FI;
1162         for (const auto &PS : FS->paramAccesses()) {
1163           auto &US =
1164               FI.Params
1165                   .emplace(PS.ParamNo, FunctionSummary::ParamAccess::RangeWidth)
1166                   .first->second;
1167           US.Range = PS.Use;
1168           for (const auto &Call : PS.Calls) {
1169             assert(!Call.Offsets.isFullSet());
1170             FunctionSummary *S =
1171                 findCalleeFunctionSummary(Call.Callee, FS->modulePath());
1172             ++NumCombinedCalleeLookupTotal;
1173             if (!S) {
1174               ++NumCombinedCalleeLookupFailed;
1175               US.Range = FullSet;
1176               US.Calls.clear();
1177               break;
1178             }
1179             US.Calls.emplace(CallInfo<FunctionSummary>(S, Call.ParamNo),
1180                              Call.Offsets);
1181           }
1182         }
1183         Functions.emplace(FS, std::move(FI));
1184       }
1185       // Reset data for all summaries. Alive and DSO local will be set back from
1186       // of data flow results below. Anything else will not be accessed
1187       // by ThinLTO backend, so we can save on bitcode size.
1188       FS->setParamAccesses({});
1189     }
1190   }
1191   NumCombinedDataFlowNodes += Functions.size();
1192   StackSafetyDataFlowAnalysis<FunctionSummary> SSDFA(
1193       FunctionSummary::ParamAccess::RangeWidth, std::move(Functions));
1194   for (const auto &KV : SSDFA.run()) {
1195     std::vector<FunctionSummary::ParamAccess> NewParams;
1196     NewParams.reserve(KV.second.Params.size());
1197     for (const auto &Param : KV.second.Params) {
1198       // It's not needed as FullSet is processed the same as a missing value.
1199       if (Param.second.Range.isFullSet())
1200         continue;
1201       NewParams.emplace_back();
1202       FunctionSummary::ParamAccess &New = NewParams.back();
1203       New.ParamNo = Param.first;
1204       New.Use = Param.second.Range; // Only range is needed.
1205     }
1206     const_cast<FunctionSummary *>(KV.first)->setParamAccesses(
1207         std::move(NewParams));
1208   }
1209 
1210   CountParamAccesses(NumCombinedParamAccessesAfter);
1211 }
1212 
1213 static const char LocalPassArg[] = "stack-safety-local";
1214 static const char LocalPassName[] = "Stack Safety Local Analysis";
1215 INITIALIZE_PASS_BEGIN(StackSafetyInfoWrapperPass, LocalPassArg, LocalPassName,
1216                       false, true)
1217 INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
1218 INITIALIZE_PASS_END(StackSafetyInfoWrapperPass, LocalPassArg, LocalPassName,
1219                     false, true)
1220 
1221 static const char GlobalPassName[] = "Stack Safety Analysis";
1222 INITIALIZE_PASS_BEGIN(StackSafetyGlobalInfoWrapperPass, DEBUG_TYPE,
1223                       GlobalPassName, false, true)
1224 INITIALIZE_PASS_DEPENDENCY(StackSafetyInfoWrapperPass)
1225 INITIALIZE_PASS_DEPENDENCY(ImmutableModuleSummaryIndexWrapperPass)
1226 INITIALIZE_PASS_END(StackSafetyGlobalInfoWrapperPass, DEBUG_TYPE,
1227                     GlobalPassName, false, true)
1228