xref: /llvm-project/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp (revision 1de71652fd232163dadfee68e2f2b3f0d6dfb1e1)
1 //===- ModuleSummaryAnalysis.cpp - Module summary index builder -----------===//
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 // This pass builds a ModuleSummaryIndex object for the module, to be written
10 // to bitcode or LLVM assembly.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Analysis/ModuleSummaryAnalysis.h"
15 #include "llvm/ADT/ArrayRef.h"
16 #include "llvm/ADT/DenseSet.h"
17 #include "llvm/ADT/MapVector.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/SetVector.h"
20 #include "llvm/ADT/SmallPtrSet.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/StringRef.h"
23 #include "llvm/Analysis/BlockFrequencyInfo.h"
24 #include "llvm/Analysis/BranchProbabilityInfo.h"
25 #include "llvm/Analysis/ConstantFolding.h"
26 #include "llvm/Analysis/IndirectCallPromotionAnalysis.h"
27 #include "llvm/Analysis/LoopInfo.h"
28 #include "llvm/Analysis/MemoryProfileInfo.h"
29 #include "llvm/Analysis/ProfileSummaryInfo.h"
30 #include "llvm/Analysis/StackSafetyAnalysis.h"
31 #include "llvm/Analysis/TypeMetadataUtils.h"
32 #include "llvm/IR/Attributes.h"
33 #include "llvm/IR/BasicBlock.h"
34 #include "llvm/IR/Constant.h"
35 #include "llvm/IR/Constants.h"
36 #include "llvm/IR/Dominators.h"
37 #include "llvm/IR/Function.h"
38 #include "llvm/IR/GlobalAlias.h"
39 #include "llvm/IR/GlobalValue.h"
40 #include "llvm/IR/GlobalVariable.h"
41 #include "llvm/IR/Instructions.h"
42 #include "llvm/IR/IntrinsicInst.h"
43 #include "llvm/IR/Metadata.h"
44 #include "llvm/IR/Module.h"
45 #include "llvm/IR/ModuleSummaryIndex.h"
46 #include "llvm/IR/Use.h"
47 #include "llvm/IR/User.h"
48 #include "llvm/InitializePasses.h"
49 #include "llvm/Object/ModuleSymbolTable.h"
50 #include "llvm/Object/SymbolicFile.h"
51 #include "llvm/Pass.h"
52 #include "llvm/Support/Casting.h"
53 #include "llvm/Support/CommandLine.h"
54 #include "llvm/Support/FileSystem.h"
55 #include <algorithm>
56 #include <cassert>
57 #include <cstdint>
58 #include <vector>
59 
60 using namespace llvm;
61 using namespace llvm::memprof;
62 
63 #define DEBUG_TYPE "module-summary-analysis"
64 
65 // Option to force edges cold which will block importing when the
66 // -import-cold-multiplier is set to 0. Useful for debugging.
67 namespace llvm {
68 FunctionSummary::ForceSummaryHotnessType ForceSummaryEdgesCold =
69     FunctionSummary::FSHT_None;
70 } // namespace llvm
71 
72 static cl::opt<FunctionSummary::ForceSummaryHotnessType, true> FSEC(
73     "force-summary-edges-cold", cl::Hidden, cl::location(ForceSummaryEdgesCold),
74     cl::desc("Force all edges in the function summary to cold"),
75     cl::values(clEnumValN(FunctionSummary::FSHT_None, "none", "None."),
76                clEnumValN(FunctionSummary::FSHT_AllNonCritical,
77                           "all-non-critical", "All non-critical edges."),
78                clEnumValN(FunctionSummary::FSHT_All, "all", "All edges.")));
79 
80 static cl::opt<std::string> ModuleSummaryDotFile(
81     "module-summary-dot-file", cl::Hidden, cl::value_desc("filename"),
82     cl::desc("File to emit dot graph of new summary into"));
83 
84 static cl::opt<bool> EnableMemProfIndirectCallSupport(
85     "enable-memprof-indirect-call-support", cl::init(true), cl::Hidden,
86     cl::desc(
87         "Enable MemProf support for summarizing and cloning indirect calls"));
88 
89 extern cl::opt<bool> ScalePartialSampleProfileWorkingSetSize;
90 
91 extern cl::opt<unsigned> MaxNumVTableAnnotations;
92 
93 extern cl::opt<bool> MemProfReportHintedSizes;
94 
95 // Walk through the operands of a given User via worklist iteration and populate
96 // the set of GlobalValue references encountered. Invoked either on an
97 // Instruction or a GlobalVariable (which walks its initializer).
98 // Return true if any of the operands contains blockaddress. This is important
99 // to know when computing summary for global var, because if global variable
100 // references basic block address we can't import it separately from function
101 // containing that basic block. For simplicity we currently don't import such
102 // global vars at all. When importing function we aren't interested if any
103 // instruction in it takes an address of any basic block, because instruction
104 // can only take an address of basic block located in the same function.
105 // Set `RefLocalLinkageIFunc` to true if the analyzed value references a
106 // local-linkage ifunc.
107 static bool
108 findRefEdges(ModuleSummaryIndex &Index, const User *CurUser,
109              SetVector<ValueInfo, SmallVector<ValueInfo, 0>> &RefEdges,
110              SmallPtrSet<const User *, 8> &Visited,
111              bool &RefLocalLinkageIFunc) {
112   bool HasBlockAddress = false;
113   SmallVector<const User *, 32> Worklist;
114   if (Visited.insert(CurUser).second)
115     Worklist.push_back(CurUser);
116 
117   while (!Worklist.empty()) {
118     const User *U = Worklist.pop_back_val();
119     const auto *CB = dyn_cast<CallBase>(U);
120 
121     for (const auto &OI : U->operands()) {
122       const User *Operand = dyn_cast<User>(OI);
123       if (!Operand)
124         continue;
125       if (isa<BlockAddress>(Operand)) {
126         HasBlockAddress = true;
127         continue;
128       }
129       if (auto *GV = dyn_cast<GlobalValue>(Operand)) {
130         // We have a reference to a global value. This should be added to
131         // the reference set unless it is a callee. Callees are handled
132         // specially by WriteFunction and are added to a separate list.
133         if (!(CB && CB->isCallee(&OI))) {
134           // If an ifunc has local linkage, do not add it into ref edges, and
135           // sets `RefLocalLinkageIFunc` to true. The referencer is not eligible
136           // for import. An ifunc doesn't have summary and ThinLTO cannot
137           // promote it; importing the referencer may cause linkage errors.
138           if (auto *GI = dyn_cast_if_present<GlobalIFunc>(GV);
139               GI && GI->hasLocalLinkage()) {
140             RefLocalLinkageIFunc = true;
141             continue;
142           }
143           RefEdges.insert(Index.getOrInsertValueInfo(GV));
144         }
145         continue;
146       }
147       if (Visited.insert(Operand).second)
148         Worklist.push_back(Operand);
149     }
150   }
151 
152   const Instruction *I = dyn_cast<Instruction>(CurUser);
153   if (I) {
154     uint64_t TotalCount = 0;
155     // MaxNumVTableAnnotations is the maximum number of vtables annotated on
156     // the instruction.
157     auto ValueDataArray = getValueProfDataFromInst(
158         *I, IPVK_VTableTarget, MaxNumVTableAnnotations, TotalCount);
159 
160     for (const auto &V : ValueDataArray)
161       RefEdges.insert(Index.getOrInsertValueInfo(/* VTableGUID = */
162                                                  V.Value));
163   }
164   return HasBlockAddress;
165 }
166 
167 static CalleeInfo::HotnessType getHotness(uint64_t ProfileCount,
168                                           ProfileSummaryInfo *PSI) {
169   if (!PSI)
170     return CalleeInfo::HotnessType::Unknown;
171   if (PSI->isHotCount(ProfileCount))
172     return CalleeInfo::HotnessType::Hot;
173   if (PSI->isColdCount(ProfileCount))
174     return CalleeInfo::HotnessType::Cold;
175   return CalleeInfo::HotnessType::None;
176 }
177 
178 static bool isNonRenamableLocal(const GlobalValue &GV) {
179   return GV.hasSection() && GV.hasLocalLinkage();
180 }
181 
182 /// Determine whether this call has all constant integer arguments (excluding
183 /// "this") and summarize it to VCalls or ConstVCalls as appropriate.
184 static void addVCallToSet(
185     DevirtCallSite Call, GlobalValue::GUID Guid,
186     SetVector<FunctionSummary::VFuncId, std::vector<FunctionSummary::VFuncId>>
187         &VCalls,
188     SetVector<FunctionSummary::ConstVCall,
189               std::vector<FunctionSummary::ConstVCall>> &ConstVCalls) {
190   std::vector<uint64_t> Args;
191   // Start from the second argument to skip the "this" pointer.
192   for (auto &Arg : drop_begin(Call.CB.args())) {
193     auto *CI = dyn_cast<ConstantInt>(Arg);
194     if (!CI || CI->getBitWidth() > 64) {
195       VCalls.insert({Guid, Call.Offset});
196       return;
197     }
198     Args.push_back(CI->getZExtValue());
199   }
200   ConstVCalls.insert({{Guid, Call.Offset}, std::move(Args)});
201 }
202 
203 /// If this intrinsic call requires that we add information to the function
204 /// summary, do so via the non-constant reference arguments.
205 static void addIntrinsicToSummary(
206     const CallInst *CI,
207     SetVector<GlobalValue::GUID, std::vector<GlobalValue::GUID>> &TypeTests,
208     SetVector<FunctionSummary::VFuncId, std::vector<FunctionSummary::VFuncId>>
209         &TypeTestAssumeVCalls,
210     SetVector<FunctionSummary::VFuncId, std::vector<FunctionSummary::VFuncId>>
211         &TypeCheckedLoadVCalls,
212     SetVector<FunctionSummary::ConstVCall,
213               std::vector<FunctionSummary::ConstVCall>>
214         &TypeTestAssumeConstVCalls,
215     SetVector<FunctionSummary::ConstVCall,
216               std::vector<FunctionSummary::ConstVCall>>
217         &TypeCheckedLoadConstVCalls,
218     DominatorTree &DT) {
219   switch (CI->getCalledFunction()->getIntrinsicID()) {
220   case Intrinsic::type_test:
221   case Intrinsic::public_type_test: {
222     auto *TypeMDVal = cast<MetadataAsValue>(CI->getArgOperand(1));
223     auto *TypeId = dyn_cast<MDString>(TypeMDVal->getMetadata());
224     if (!TypeId)
225       break;
226     GlobalValue::GUID Guid = GlobalValue::getGUID(TypeId->getString());
227 
228     // Produce a summary from type.test intrinsics. We only summarize type.test
229     // intrinsics that are used other than by an llvm.assume intrinsic.
230     // Intrinsics that are assumed are relevant only to the devirtualization
231     // pass, not the type test lowering pass.
232     bool HasNonAssumeUses = llvm::any_of(CI->uses(), [](const Use &CIU) {
233       return !isa<AssumeInst>(CIU.getUser());
234     });
235     if (HasNonAssumeUses)
236       TypeTests.insert(Guid);
237 
238     SmallVector<DevirtCallSite, 4> DevirtCalls;
239     SmallVector<CallInst *, 4> Assumes;
240     findDevirtualizableCallsForTypeTest(DevirtCalls, Assumes, CI, DT);
241     for (auto &Call : DevirtCalls)
242       addVCallToSet(Call, Guid, TypeTestAssumeVCalls,
243                     TypeTestAssumeConstVCalls);
244 
245     break;
246   }
247 
248   case Intrinsic::type_checked_load_relative:
249   case Intrinsic::type_checked_load: {
250     auto *TypeMDVal = cast<MetadataAsValue>(CI->getArgOperand(2));
251     auto *TypeId = dyn_cast<MDString>(TypeMDVal->getMetadata());
252     if (!TypeId)
253       break;
254     GlobalValue::GUID Guid = GlobalValue::getGUID(TypeId->getString());
255 
256     SmallVector<DevirtCallSite, 4> DevirtCalls;
257     SmallVector<Instruction *, 4> LoadedPtrs;
258     SmallVector<Instruction *, 4> Preds;
259     bool HasNonCallUses = false;
260     findDevirtualizableCallsForTypeCheckedLoad(DevirtCalls, LoadedPtrs, Preds,
261                                                HasNonCallUses, CI, DT);
262     // Any non-call uses of the result of llvm.type.checked.load will
263     // prevent us from optimizing away the llvm.type.test.
264     if (HasNonCallUses)
265       TypeTests.insert(Guid);
266     for (auto &Call : DevirtCalls)
267       addVCallToSet(Call, Guid, TypeCheckedLoadVCalls,
268                     TypeCheckedLoadConstVCalls);
269 
270     break;
271   }
272   default:
273     break;
274   }
275 }
276 
277 static bool isNonVolatileLoad(const Instruction *I) {
278   if (const auto *LI = dyn_cast<LoadInst>(I))
279     return !LI->isVolatile();
280 
281   return false;
282 }
283 
284 static bool isNonVolatileStore(const Instruction *I) {
285   if (const auto *SI = dyn_cast<StoreInst>(I))
286     return !SI->isVolatile();
287 
288   return false;
289 }
290 
291 // Returns true if the function definition must be unreachable.
292 //
293 // Note if this helper function returns true, `F` is guaranteed
294 // to be unreachable; if it returns false, `F` might still
295 // be unreachable but not covered by this helper function.
296 static bool mustBeUnreachableFunction(const Function &F) {
297   // A function must be unreachable if its entry block ends with an
298   // 'unreachable'.
299   assert(!F.isDeclaration());
300   return isa<UnreachableInst>(F.getEntryBlock().getTerminator());
301 }
302 
303 static void computeFunctionSummary(
304     ModuleSummaryIndex &Index, const Module &M, const Function &F,
305     BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI, DominatorTree &DT,
306     bool HasLocalsInUsedOrAsm, DenseSet<GlobalValue::GUID> &CantBePromoted,
307     bool IsThinLTO,
308     std::function<const StackSafetyInfo *(const Function &F)> GetSSICallback) {
309   // Summary not currently supported for anonymous functions, they should
310   // have been named.
311   assert(F.hasName());
312 
313   unsigned NumInsts = 0;
314   // Map from callee ValueId to profile count. Used to accumulate profile
315   // counts for all static calls to a given callee.
316   MapVector<ValueInfo, CalleeInfo, DenseMap<ValueInfo, unsigned>,
317             SmallVector<FunctionSummary::EdgeTy, 0>>
318       CallGraphEdges;
319   SetVector<ValueInfo, SmallVector<ValueInfo, 0>> RefEdges, LoadRefEdges,
320       StoreRefEdges;
321   SetVector<GlobalValue::GUID, std::vector<GlobalValue::GUID>> TypeTests;
322   SetVector<FunctionSummary::VFuncId, std::vector<FunctionSummary::VFuncId>>
323       TypeTestAssumeVCalls, TypeCheckedLoadVCalls;
324   SetVector<FunctionSummary::ConstVCall,
325             std::vector<FunctionSummary::ConstVCall>>
326       TypeTestAssumeConstVCalls, TypeCheckedLoadConstVCalls;
327   ICallPromotionAnalysis ICallAnalysis;
328   SmallPtrSet<const User *, 8> Visited;
329 
330   // Add personality function, prefix data and prologue data to function's ref
331   // list.
332   bool HasLocalIFuncCallOrRef = false;
333   findRefEdges(Index, &F, RefEdges, Visited, HasLocalIFuncCallOrRef);
334   std::vector<const Instruction *> NonVolatileLoads;
335   std::vector<const Instruction *> NonVolatileStores;
336 
337   std::vector<CallsiteInfo> Callsites;
338   std::vector<AllocInfo> Allocs;
339 
340 #ifndef NDEBUG
341   DenseSet<const CallBase *> CallsThatMayHaveMemprofSummary;
342 #endif
343 
344   bool HasInlineAsmMaybeReferencingInternal = false;
345   bool HasIndirBranchToBlockAddress = false;
346   bool HasUnknownCall = false;
347   bool MayThrow = false;
348   for (const BasicBlock &BB : F) {
349     // We don't allow inlining of function with indirect branch to blockaddress.
350     // If the blockaddress escapes the function, e.g., via a global variable,
351     // inlining may lead to an invalid cross-function reference. So we shouldn't
352     // import such function either.
353     if (BB.hasAddressTaken()) {
354       for (User *U : BlockAddress::get(const_cast<BasicBlock *>(&BB))->users())
355         if (!isa<CallBrInst>(*U)) {
356           HasIndirBranchToBlockAddress = true;
357           break;
358         }
359     }
360 
361     for (const Instruction &I : BB) {
362       if (I.isDebugOrPseudoInst())
363         continue;
364       ++NumInsts;
365 
366       // Regular LTO module doesn't participate in ThinLTO import,
367       // so no reference from it can be read/writeonly, since this
368       // would require importing variable as local copy
369       if (IsThinLTO) {
370         if (isNonVolatileLoad(&I)) {
371           // Postpone processing of non-volatile load instructions
372           // See comments below
373           Visited.insert(&I);
374           NonVolatileLoads.push_back(&I);
375           continue;
376         } else if (isNonVolatileStore(&I)) {
377           Visited.insert(&I);
378           NonVolatileStores.push_back(&I);
379           // All references from second operand of store (destination address)
380           // can be considered write-only if they're not referenced by any
381           // non-store instruction. References from first operand of store
382           // (stored value) can't be treated either as read- or as write-only
383           // so we add them to RefEdges as we do with all other instructions
384           // except non-volatile load.
385           Value *Stored = I.getOperand(0);
386           if (auto *GV = dyn_cast<GlobalValue>(Stored))
387             // findRefEdges will try to examine GV operands, so instead
388             // of calling it we should add GV to RefEdges directly.
389             RefEdges.insert(Index.getOrInsertValueInfo(GV));
390           else if (auto *U = dyn_cast<User>(Stored))
391             findRefEdges(Index, U, RefEdges, Visited, HasLocalIFuncCallOrRef);
392           continue;
393         }
394       }
395       findRefEdges(Index, &I, RefEdges, Visited, HasLocalIFuncCallOrRef);
396       const auto *CB = dyn_cast<CallBase>(&I);
397       if (!CB) {
398         if (I.mayThrow())
399           MayThrow = true;
400         continue;
401       }
402 
403       const auto *CI = dyn_cast<CallInst>(&I);
404       // Since we don't know exactly which local values are referenced in inline
405       // assembly, conservatively mark the function as possibly referencing
406       // a local value from inline assembly to ensure we don't export a
407       // reference (which would require renaming and promotion of the
408       // referenced value).
409       if (HasLocalsInUsedOrAsm && CI && CI->isInlineAsm())
410         HasInlineAsmMaybeReferencingInternal = true;
411 
412       // Compute this once per indirect call.
413       uint32_t NumCandidates = 0;
414       uint64_t TotalCount = 0;
415       MutableArrayRef<InstrProfValueData> CandidateProfileData;
416 
417       auto *CalledValue = CB->getCalledOperand();
418       auto *CalledFunction = CB->getCalledFunction();
419       if (CalledValue && !CalledFunction) {
420         CalledValue = CalledValue->stripPointerCasts();
421         // Stripping pointer casts can reveal a called function.
422         CalledFunction = dyn_cast<Function>(CalledValue);
423       }
424       // Check if this is an alias to a function. If so, get the
425       // called aliasee for the checks below.
426       if (auto *GA = dyn_cast<GlobalAlias>(CalledValue)) {
427         assert(!CalledFunction && "Expected null called function in callsite for alias");
428         CalledFunction = dyn_cast<Function>(GA->getAliaseeObject());
429       }
430       // Check if this is a direct call to a known function or a known
431       // intrinsic, or an indirect call with profile data.
432       if (CalledFunction) {
433         if (CI && CalledFunction->isIntrinsic()) {
434           addIntrinsicToSummary(
435               CI, TypeTests, TypeTestAssumeVCalls, TypeCheckedLoadVCalls,
436               TypeTestAssumeConstVCalls, TypeCheckedLoadConstVCalls, DT);
437           continue;
438         }
439         // We should have named any anonymous globals
440         assert(CalledFunction->hasName());
441         auto ScaledCount = PSI->getProfileCount(*CB, BFI);
442         auto Hotness = ScaledCount ? getHotness(*ScaledCount, PSI)
443                                    : CalleeInfo::HotnessType::Unknown;
444         if (ForceSummaryEdgesCold != FunctionSummary::FSHT_None)
445           Hotness = CalleeInfo::HotnessType::Cold;
446 
447         // Use the original CalledValue, in case it was an alias. We want
448         // to record the call edge to the alias in that case. Eventually
449         // an alias summary will be created to associate the alias and
450         // aliasee.
451         auto &ValueInfo = CallGraphEdges[Index.getOrInsertValueInfo(
452             cast<GlobalValue>(CalledValue))];
453         ValueInfo.updateHotness(Hotness);
454         if (CB->isTailCall())
455           ValueInfo.setHasTailCall(true);
456         // Add the relative block frequency to CalleeInfo if there is no profile
457         // information.
458         if (BFI != nullptr && Hotness == CalleeInfo::HotnessType::Unknown) {
459           uint64_t BBFreq = BFI->getBlockFreq(&BB).getFrequency();
460           uint64_t EntryFreq = BFI->getEntryFreq().getFrequency();
461           ValueInfo.updateRelBlockFreq(BBFreq, EntryFreq);
462         }
463       } else {
464         HasUnknownCall = true;
465         // If F is imported, a local linkage ifunc (e.g. target_clones on a
466         // static function) called by F will be cloned. Since summaries don't
467         // track ifunc, we do not know implementation functions referenced by
468         // the ifunc resolver need to be promoted in the exporter, and we will
469         // get linker errors due to cloned declarations for implementation
470         // functions. As a simple fix, just mark F as not eligible for import.
471         // Non-local ifunc is not cloned and does not have the issue.
472         if (auto *GI = dyn_cast_if_present<GlobalIFunc>(CalledValue))
473           if (GI->hasLocalLinkage())
474             HasLocalIFuncCallOrRef = true;
475         // Skip inline assembly calls.
476         if (CI && CI->isInlineAsm())
477           continue;
478         // Skip direct calls.
479         if (!CalledValue || isa<Constant>(CalledValue))
480           continue;
481 
482         // Check if the instruction has a callees metadata. If so, add callees
483         // to CallGraphEdges to reflect the references from the metadata, and
484         // to enable importing for subsequent indirect call promotion and
485         // inlining.
486         if (auto *MD = I.getMetadata(LLVMContext::MD_callees)) {
487           for (const auto &Op : MD->operands()) {
488             Function *Callee = mdconst::extract_or_null<Function>(Op);
489             if (Callee)
490               CallGraphEdges[Index.getOrInsertValueInfo(Callee)];
491           }
492         }
493 
494         CandidateProfileData =
495             ICallAnalysis.getPromotionCandidatesForInstruction(&I, TotalCount,
496                                                                NumCandidates);
497         for (const auto &Candidate : CandidateProfileData)
498           CallGraphEdges[Index.getOrInsertValueInfo(Candidate.Value)]
499               .updateHotness(getHotness(Candidate.Count, PSI));
500       }
501 
502       // Summarize memprof related metadata. This is only needed for ThinLTO.
503       if (!IsThinLTO)
504         continue;
505 
506       // Ensure we keep this analysis in sync with the handling in the ThinLTO
507       // backend (see MemProfContextDisambiguation::applyImport). Save this call
508       // so that we can skip it in checking the reverse case later.
509       assert(mayHaveMemprofSummary(CB));
510 #ifndef NDEBUG
511       CallsThatMayHaveMemprofSummary.insert(CB);
512 #endif
513 
514       // Compute the list of stack ids first (so we can trim them from the stack
515       // ids on any MIBs).
516       CallStack<MDNode, MDNode::op_iterator> InstCallsite(
517           I.getMetadata(LLVMContext::MD_callsite));
518       auto *MemProfMD = I.getMetadata(LLVMContext::MD_memprof);
519       if (MemProfMD) {
520         std::vector<MIBInfo> MIBs;
521         std::vector<uint64_t> TotalSizes;
522         for (auto &MDOp : MemProfMD->operands()) {
523           auto *MIBMD = cast<const MDNode>(MDOp);
524           MDNode *StackNode = getMIBStackNode(MIBMD);
525           assert(StackNode);
526           SmallVector<unsigned> StackIdIndices;
527           CallStack<MDNode, MDNode::op_iterator> StackContext(StackNode);
528           // Collapse out any on the allocation call (inlining).
529           for (auto ContextIter =
530                    StackContext.beginAfterSharedPrefix(InstCallsite);
531                ContextIter != StackContext.end(); ++ContextIter) {
532             unsigned StackIdIdx = Index.addOrGetStackIdIndex(*ContextIter);
533             // If this is a direct recursion, simply skip the duplicate
534             // entries. If this is mutual recursion, handling is left to
535             // the LTO link analysis client.
536             if (StackIdIndices.empty() || StackIdIndices.back() != StackIdIdx)
537               StackIdIndices.push_back(StackIdIdx);
538           }
539           MIBs.push_back(
540               MIBInfo(getMIBAllocType(MIBMD), std::move(StackIdIndices)));
541           if (MemProfReportHintedSizes) {
542             auto TotalSize = getMIBTotalSize(MIBMD);
543             assert(TotalSize);
544             TotalSizes.push_back(TotalSize);
545           }
546         }
547         Allocs.push_back(AllocInfo(std::move(MIBs)));
548         if (MemProfReportHintedSizes) {
549           assert(Allocs.back().MIBs.size() == TotalSizes.size());
550           Allocs.back().TotalSizes = std::move(TotalSizes);
551         }
552       } else if (!InstCallsite.empty()) {
553         SmallVector<unsigned> StackIdIndices;
554         for (auto StackId : InstCallsite)
555           StackIdIndices.push_back(Index.addOrGetStackIdIndex(StackId));
556         if (CalledFunction) {
557           // Use the original CalledValue, in case it was an alias. We want
558           // to record the call edge to the alias in that case. Eventually
559           // an alias summary will be created to associate the alias and
560           // aliasee.
561           auto CalleeValueInfo =
562               Index.getOrInsertValueInfo(cast<GlobalValue>(CalledValue));
563           Callsites.push_back({CalleeValueInfo, StackIdIndices});
564         } else if (EnableMemProfIndirectCallSupport) {
565           // For indirect callsites, create multiple Callsites, one per target.
566           // This enables having a different set of clone versions per target,
567           // and we will apply the cloning decisions while speculatively
568           // devirtualizing in the ThinLTO backends.
569           for (const auto &Candidate : CandidateProfileData) {
570             auto CalleeValueInfo = Index.getOrInsertValueInfo(Candidate.Value);
571             Callsites.push_back({CalleeValueInfo, StackIdIndices});
572           }
573         }
574       }
575     }
576   }
577 
578   if (PSI->hasPartialSampleProfile() && ScalePartialSampleProfileWorkingSetSize)
579     Index.addBlockCount(F.size());
580 
581   SmallVector<ValueInfo, 0> Refs;
582   if (IsThinLTO) {
583     auto AddRefEdges =
584         [&](const std::vector<const Instruction *> &Instrs,
585             SetVector<ValueInfo, SmallVector<ValueInfo, 0>> &Edges,
586             SmallPtrSet<const User *, 8> &Cache) {
587           for (const auto *I : Instrs) {
588             Cache.erase(I);
589             findRefEdges(Index, I, Edges, Cache, HasLocalIFuncCallOrRef);
590           }
591         };
592 
593     // By now we processed all instructions in a function, except
594     // non-volatile loads and non-volatile value stores. Let's find
595     // ref edges for both of instruction sets
596     AddRefEdges(NonVolatileLoads, LoadRefEdges, Visited);
597     // We can add some values to the Visited set when processing load
598     // instructions which are also used by stores in NonVolatileStores.
599     // For example this can happen if we have following code:
600     //
601     // store %Derived* @foo, %Derived** bitcast (%Base** @bar to %Derived**)
602     // %42 = load %Derived*, %Derived** bitcast (%Base** @bar to %Derived**)
603     //
604     // After processing loads we'll add bitcast to the Visited set, and if
605     // we use the same set while processing stores, we'll never see store
606     // to @bar and @bar will be mistakenly treated as readonly.
607     SmallPtrSet<const llvm::User *, 8> StoreCache;
608     AddRefEdges(NonVolatileStores, StoreRefEdges, StoreCache);
609 
610     // If both load and store instruction reference the same variable
611     // we won't be able to optimize it. Add all such reference edges
612     // to RefEdges set.
613     for (const auto &VI : StoreRefEdges)
614       if (LoadRefEdges.remove(VI))
615         RefEdges.insert(VI);
616 
617     unsigned RefCnt = RefEdges.size();
618     // All new reference edges inserted in two loops below are either
619     // read or write only. They will be grouped in the end of RefEdges
620     // vector, so we can use a single integer value to identify them.
621     for (const auto &VI : LoadRefEdges)
622       RefEdges.insert(VI);
623 
624     unsigned FirstWORef = RefEdges.size();
625     for (const auto &VI : StoreRefEdges)
626       RefEdges.insert(VI);
627 
628     Refs = RefEdges.takeVector();
629     for (; RefCnt < FirstWORef; ++RefCnt)
630       Refs[RefCnt].setReadOnly();
631 
632     for (; RefCnt < Refs.size(); ++RefCnt)
633       Refs[RefCnt].setWriteOnly();
634   } else {
635     Refs = RefEdges.takeVector();
636   }
637   // Explicit add hot edges to enforce importing for designated GUIDs for
638   // sample PGO, to enable the same inlines as the profiled optimized binary.
639   for (auto &I : F.getImportGUIDs())
640     CallGraphEdges[Index.getOrInsertValueInfo(I)].updateHotness(
641         ForceSummaryEdgesCold == FunctionSummary::FSHT_All
642             ? CalleeInfo::HotnessType::Cold
643             : CalleeInfo::HotnessType::Critical);
644 
645 #ifndef NDEBUG
646   // Make sure that all calls we decided could not have memprof summaries get a
647   // false value for mayHaveMemprofSummary, to ensure that this handling remains
648   // in sync with the ThinLTO backend handling.
649   if (IsThinLTO) {
650     for (const BasicBlock &BB : F) {
651       for (const Instruction &I : BB) {
652         const auto *CB = dyn_cast<CallBase>(&I);
653         if (!CB)
654           continue;
655         // We already checked these above.
656         if (CallsThatMayHaveMemprofSummary.count(CB))
657           continue;
658         assert(!mayHaveMemprofSummary(CB));
659       }
660     }
661   }
662 #endif
663 
664   bool NonRenamableLocal = isNonRenamableLocal(F);
665   bool NotEligibleForImport =
666       NonRenamableLocal || HasInlineAsmMaybeReferencingInternal ||
667       HasIndirBranchToBlockAddress || HasLocalIFuncCallOrRef;
668   GlobalValueSummary::GVFlags Flags(
669       F.getLinkage(), F.getVisibility(), NotEligibleForImport,
670       /* Live = */ false, F.isDSOLocal(), F.canBeOmittedFromSymbolTable(),
671       GlobalValueSummary::ImportKind::Definition);
672   FunctionSummary::FFlags FunFlags{
673       F.doesNotAccessMemory(), F.onlyReadsMemory() && !F.doesNotAccessMemory(),
674       F.hasFnAttribute(Attribute::NoRecurse), F.returnDoesNotAlias(),
675       // FIXME: refactor this to use the same code that inliner is using.
676       // Don't try to import functions with noinline attribute.
677       F.getAttributes().hasFnAttr(Attribute::NoInline),
678       F.hasFnAttribute(Attribute::AlwaysInline),
679       F.hasFnAttribute(Attribute::NoUnwind), MayThrow, HasUnknownCall,
680       mustBeUnreachableFunction(F)};
681   std::vector<FunctionSummary::ParamAccess> ParamAccesses;
682   if (auto *SSI = GetSSICallback(F))
683     ParamAccesses = SSI->getParamAccesses(Index);
684   auto FuncSummary = std::make_unique<FunctionSummary>(
685       Flags, NumInsts, FunFlags, std::move(Refs), CallGraphEdges.takeVector(),
686       TypeTests.takeVector(), TypeTestAssumeVCalls.takeVector(),
687       TypeCheckedLoadVCalls.takeVector(),
688       TypeTestAssumeConstVCalls.takeVector(),
689       TypeCheckedLoadConstVCalls.takeVector(), std::move(ParamAccesses),
690       std::move(Callsites), std::move(Allocs));
691   if (NonRenamableLocal)
692     CantBePromoted.insert(F.getGUID());
693   Index.addGlobalValueSummary(F, std::move(FuncSummary));
694 }
695 
696 /// Find function pointers referenced within the given vtable initializer
697 /// (or subset of an initializer) \p I. The starting offset of \p I within
698 /// the vtable initializer is \p StartingOffset. Any discovered function
699 /// pointers are added to \p VTableFuncs along with their cumulative offset
700 /// within the initializer.
701 static void findFuncPointers(const Constant *I, uint64_t StartingOffset,
702                              const Module &M, ModuleSummaryIndex &Index,
703                              VTableFuncList &VTableFuncs,
704                              const GlobalVariable &OrigGV) {
705   // First check if this is a function pointer.
706   if (I->getType()->isPointerTy()) {
707     auto C = I->stripPointerCasts();
708     auto A = dyn_cast<GlobalAlias>(C);
709     if (isa<Function>(C) || (A && isa<Function>(A->getAliasee()))) {
710       auto GV = dyn_cast<GlobalValue>(C);
711       assert(GV);
712       // We can disregard __cxa_pure_virtual as a possible call target, as
713       // calls to pure virtuals are UB.
714       if (GV && GV->getName() != "__cxa_pure_virtual")
715         VTableFuncs.push_back({Index.getOrInsertValueInfo(GV), StartingOffset});
716       return;
717     }
718   }
719 
720   // Walk through the elements in the constant struct or array and recursively
721   // look for virtual function pointers.
722   const DataLayout &DL = M.getDataLayout();
723   if (auto *C = dyn_cast<ConstantStruct>(I)) {
724     StructType *STy = dyn_cast<StructType>(C->getType());
725     assert(STy);
726     const StructLayout *SL = DL.getStructLayout(C->getType());
727 
728     for (auto EI : llvm::enumerate(STy->elements())) {
729       auto Offset = SL->getElementOffset(EI.index());
730       unsigned Op = SL->getElementContainingOffset(Offset);
731       findFuncPointers(cast<Constant>(I->getOperand(Op)),
732                        StartingOffset + Offset, M, Index, VTableFuncs, OrigGV);
733     }
734   } else if (auto *C = dyn_cast<ConstantArray>(I)) {
735     ArrayType *ATy = C->getType();
736     Type *EltTy = ATy->getElementType();
737     uint64_t EltSize = DL.getTypeAllocSize(EltTy);
738     for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) {
739       findFuncPointers(cast<Constant>(I->getOperand(i)),
740                        StartingOffset + i * EltSize, M, Index, VTableFuncs,
741                        OrigGV);
742     }
743   } else if (const auto *CE = dyn_cast<ConstantExpr>(I)) {
744     // For relative vtables, the next sub-component should be a trunc.
745     if (CE->getOpcode() != Instruction::Trunc ||
746         !(CE = dyn_cast<ConstantExpr>(CE->getOperand(0))))
747       return;
748 
749     // If this constant can be reduced to the offset between a function and a
750     // global, then we know this is a valid virtual function if the RHS is the
751     // original vtable we're scanning through.
752     if (CE->getOpcode() == Instruction::Sub) {
753       GlobalValue *LHS, *RHS;
754       APSInt LHSOffset, RHSOffset;
755       if (IsConstantOffsetFromGlobal(CE->getOperand(0), LHS, LHSOffset, DL) &&
756           IsConstantOffsetFromGlobal(CE->getOperand(1), RHS, RHSOffset, DL) &&
757           RHS == &OrigGV &&
758 
759           // For relative vtables, this component should point to the callable
760           // function without any offsets.
761           LHSOffset == 0 &&
762 
763           // Also, the RHS should always point to somewhere within the vtable.
764           RHSOffset <=
765               static_cast<uint64_t>(DL.getTypeAllocSize(OrigGV.getInitializer()->getType()))) {
766         findFuncPointers(LHS, StartingOffset, M, Index, VTableFuncs, OrigGV);
767       }
768     }
769   }
770 }
771 
772 // Identify the function pointers referenced by vtable definition \p V.
773 static void computeVTableFuncs(ModuleSummaryIndex &Index,
774                                const GlobalVariable &V, const Module &M,
775                                VTableFuncList &VTableFuncs) {
776   if (!V.isConstant())
777     return;
778 
779   findFuncPointers(V.getInitializer(), /*StartingOffset=*/0, M, Index,
780                    VTableFuncs, V);
781 
782 #ifndef NDEBUG
783   // Validate that the VTableFuncs list is ordered by offset.
784   uint64_t PrevOffset = 0;
785   for (auto &P : VTableFuncs) {
786     // The findVFuncPointers traversal should have encountered the
787     // functions in offset order. We need to use ">=" since PrevOffset
788     // starts at 0.
789     assert(P.VTableOffset >= PrevOffset);
790     PrevOffset = P.VTableOffset;
791   }
792 #endif
793 }
794 
795 /// Record vtable definition \p V for each type metadata it references.
796 static void
797 recordTypeIdCompatibleVtableReferences(ModuleSummaryIndex &Index,
798                                        const GlobalVariable &V,
799                                        SmallVectorImpl<MDNode *> &Types) {
800   for (MDNode *Type : Types) {
801     auto TypeID = Type->getOperand(1).get();
802 
803     uint64_t Offset =
804         cast<ConstantInt>(
805             cast<ConstantAsMetadata>(Type->getOperand(0))->getValue())
806             ->getZExtValue();
807 
808     if (auto *TypeId = dyn_cast<MDString>(TypeID))
809       Index.getOrInsertTypeIdCompatibleVtableSummary(TypeId->getString())
810           .push_back({Offset, Index.getOrInsertValueInfo(&V)});
811   }
812 }
813 
814 static void computeVariableSummary(ModuleSummaryIndex &Index,
815                                    const GlobalVariable &V,
816                                    DenseSet<GlobalValue::GUID> &CantBePromoted,
817                                    const Module &M,
818                                    SmallVectorImpl<MDNode *> &Types) {
819   SetVector<ValueInfo, SmallVector<ValueInfo, 0>> RefEdges;
820   SmallPtrSet<const User *, 8> Visited;
821   bool RefLocalIFunc = false;
822   bool HasBlockAddress =
823       findRefEdges(Index, &V, RefEdges, Visited, RefLocalIFunc);
824   const bool NotEligibleForImport = (HasBlockAddress || RefLocalIFunc);
825   bool NonRenamableLocal = isNonRenamableLocal(V);
826   GlobalValueSummary::GVFlags Flags(
827       V.getLinkage(), V.getVisibility(), NonRenamableLocal,
828       /* Live = */ false, V.isDSOLocal(), V.canBeOmittedFromSymbolTable(),
829       GlobalValueSummary::Definition);
830 
831   VTableFuncList VTableFuncs;
832   // If splitting is not enabled, then we compute the summary information
833   // necessary for index-based whole program devirtualization.
834   if (!Index.enableSplitLTOUnit()) {
835     Types.clear();
836     V.getMetadata(LLVMContext::MD_type, Types);
837     if (!Types.empty()) {
838       // Identify the function pointers referenced by this vtable definition.
839       computeVTableFuncs(Index, V, M, VTableFuncs);
840 
841       // Record this vtable definition for each type metadata it references.
842       recordTypeIdCompatibleVtableReferences(Index, V, Types);
843     }
844   }
845 
846   // Don't mark variables we won't be able to internalize as read/write-only.
847   bool CanBeInternalized =
848       !V.hasComdat() && !V.hasAppendingLinkage() && !V.isInterposable() &&
849       !V.hasAvailableExternallyLinkage() && !V.hasDLLExportStorageClass();
850   bool Constant = V.isConstant();
851   GlobalVarSummary::GVarFlags VarFlags(CanBeInternalized,
852                                        Constant ? false : CanBeInternalized,
853                                        Constant, V.getVCallVisibility());
854   auto GVarSummary = std::make_unique<GlobalVarSummary>(Flags, VarFlags,
855                                                          RefEdges.takeVector());
856   if (NonRenamableLocal)
857     CantBePromoted.insert(V.getGUID());
858   if (NotEligibleForImport)
859     GVarSummary->setNotEligibleToImport();
860   if (!VTableFuncs.empty())
861     GVarSummary->setVTableFuncs(VTableFuncs);
862   Index.addGlobalValueSummary(V, std::move(GVarSummary));
863 }
864 
865 static void computeAliasSummary(ModuleSummaryIndex &Index, const GlobalAlias &A,
866                                 DenseSet<GlobalValue::GUID> &CantBePromoted) {
867   // Skip summary for indirect function aliases as summary for aliasee will not
868   // be emitted.
869   const GlobalObject *Aliasee = A.getAliaseeObject();
870   if (isa<GlobalIFunc>(Aliasee))
871     return;
872   bool NonRenamableLocal = isNonRenamableLocal(A);
873   GlobalValueSummary::GVFlags Flags(
874       A.getLinkage(), A.getVisibility(), NonRenamableLocal,
875       /* Live = */ false, A.isDSOLocal(), A.canBeOmittedFromSymbolTable(),
876       GlobalValueSummary::Definition);
877   auto AS = std::make_unique<AliasSummary>(Flags);
878   auto AliaseeVI = Index.getValueInfo(Aliasee->getGUID());
879   assert(AliaseeVI && "Alias expects aliasee summary to be available");
880   assert(AliaseeVI.getSummaryList().size() == 1 &&
881          "Expected a single entry per aliasee in per-module index");
882   AS->setAliasee(AliaseeVI, AliaseeVI.getSummaryList()[0].get());
883   if (NonRenamableLocal)
884     CantBePromoted.insert(A.getGUID());
885   Index.addGlobalValueSummary(A, std::move(AS));
886 }
887 
888 // Set LiveRoot flag on entries matching the given value name.
889 static void setLiveRoot(ModuleSummaryIndex &Index, StringRef Name) {
890   if (ValueInfo VI = Index.getValueInfo(GlobalValue::getGUID(Name)))
891     for (const auto &Summary : VI.getSummaryList())
892       Summary->setLive(true);
893 }
894 
895 ModuleSummaryIndex llvm::buildModuleSummaryIndex(
896     const Module &M,
897     std::function<BlockFrequencyInfo *(const Function &F)> GetBFICallback,
898     ProfileSummaryInfo *PSI,
899     std::function<const StackSafetyInfo *(const Function &F)> GetSSICallback) {
900   assert(PSI);
901   bool EnableSplitLTOUnit = false;
902   bool UnifiedLTO = false;
903   if (auto *MD = mdconst::extract_or_null<ConstantInt>(
904           M.getModuleFlag("EnableSplitLTOUnit")))
905     EnableSplitLTOUnit = MD->getZExtValue();
906   if (auto *MD =
907           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("UnifiedLTO")))
908     UnifiedLTO = MD->getZExtValue();
909   ModuleSummaryIndex Index(/*HaveGVs=*/true, EnableSplitLTOUnit, UnifiedLTO);
910 
911   // Identify the local values in the llvm.used and llvm.compiler.used sets,
912   // which should not be exported as they would then require renaming and
913   // promotion, but we may have opaque uses e.g. in inline asm. We collect them
914   // here because we use this information to mark functions containing inline
915   // assembly calls as not importable.
916   SmallPtrSet<GlobalValue *, 4> LocalsUsed;
917   SmallVector<GlobalValue *, 4> Used;
918   // First collect those in the llvm.used set.
919   collectUsedGlobalVariables(M, Used, /*CompilerUsed=*/false);
920   // Next collect those in the llvm.compiler.used set.
921   collectUsedGlobalVariables(M, Used, /*CompilerUsed=*/true);
922   DenseSet<GlobalValue::GUID> CantBePromoted;
923   for (auto *V : Used) {
924     if (V->hasLocalLinkage()) {
925       LocalsUsed.insert(V);
926       CantBePromoted.insert(V->getGUID());
927     }
928   }
929 
930   bool HasLocalInlineAsmSymbol = false;
931   if (!M.getModuleInlineAsm().empty()) {
932     // Collect the local values defined by module level asm, and set up
933     // summaries for these symbols so that they can be marked as NoRename,
934     // to prevent export of any use of them in regular IR that would require
935     // renaming within the module level asm. Note we don't need to create a
936     // summary for weak or global defs, as they don't need to be flagged as
937     // NoRename, and defs in module level asm can't be imported anyway.
938     // Also, any values used but not defined within module level asm should
939     // be listed on the llvm.used or llvm.compiler.used global and marked as
940     // referenced from there.
941     ModuleSymbolTable::CollectAsmSymbols(
942         M, [&](StringRef Name, object::BasicSymbolRef::Flags Flags) {
943           // Symbols not marked as Weak or Global are local definitions.
944           if (Flags & (object::BasicSymbolRef::SF_Weak |
945                        object::BasicSymbolRef::SF_Global))
946             return;
947           HasLocalInlineAsmSymbol = true;
948           GlobalValue *GV = M.getNamedValue(Name);
949           if (!GV)
950             return;
951           assert(GV->isDeclaration() && "Def in module asm already has definition");
952           GlobalValueSummary::GVFlags GVFlags(
953               GlobalValue::InternalLinkage, GlobalValue::DefaultVisibility,
954               /* NotEligibleToImport = */ true,
955               /* Live = */ true,
956               /* Local */ GV->isDSOLocal(), GV->canBeOmittedFromSymbolTable(),
957               GlobalValueSummary::Definition);
958           CantBePromoted.insert(GV->getGUID());
959           // Create the appropriate summary type.
960           if (Function *F = dyn_cast<Function>(GV)) {
961             std::unique_ptr<FunctionSummary> Summary =
962                 std::make_unique<FunctionSummary>(
963                     GVFlags, /*InstCount=*/0,
964                     FunctionSummary::FFlags{
965                         F->hasFnAttribute(Attribute::ReadNone),
966                         F->hasFnAttribute(Attribute::ReadOnly),
967                         F->hasFnAttribute(Attribute::NoRecurse),
968                         F->returnDoesNotAlias(),
969                         /* NoInline = */ false,
970                         F->hasFnAttribute(Attribute::AlwaysInline),
971                         F->hasFnAttribute(Attribute::NoUnwind),
972                         /* MayThrow */ true,
973                         /* HasUnknownCall */ true,
974                         /* MustBeUnreachable */ false},
975                     SmallVector<ValueInfo, 0>{},
976                     SmallVector<FunctionSummary::EdgeTy, 0>{},
977                     ArrayRef<GlobalValue::GUID>{},
978                     ArrayRef<FunctionSummary::VFuncId>{},
979                     ArrayRef<FunctionSummary::VFuncId>{},
980                     ArrayRef<FunctionSummary::ConstVCall>{},
981                     ArrayRef<FunctionSummary::ConstVCall>{},
982                     ArrayRef<FunctionSummary::ParamAccess>{},
983                     ArrayRef<CallsiteInfo>{}, ArrayRef<AllocInfo>{});
984             Index.addGlobalValueSummary(*GV, std::move(Summary));
985           } else {
986             std::unique_ptr<GlobalVarSummary> Summary =
987                 std::make_unique<GlobalVarSummary>(
988                     GVFlags,
989                     GlobalVarSummary::GVarFlags(
990                         false, false, cast<GlobalVariable>(GV)->isConstant(),
991                         GlobalObject::VCallVisibilityPublic),
992                     SmallVector<ValueInfo, 0>{});
993             Index.addGlobalValueSummary(*GV, std::move(Summary));
994           }
995         });
996   }
997 
998   bool IsThinLTO = true;
999   if (auto *MD =
1000           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
1001     IsThinLTO = MD->getZExtValue();
1002 
1003   // Compute summaries for all functions defined in module, and save in the
1004   // index.
1005   for (const auto &F : M) {
1006     if (F.isDeclaration())
1007       continue;
1008 
1009     DominatorTree DT(const_cast<Function &>(F));
1010     BlockFrequencyInfo *BFI = nullptr;
1011     std::unique_ptr<BlockFrequencyInfo> BFIPtr;
1012     if (GetBFICallback)
1013       BFI = GetBFICallback(F);
1014     else if (F.hasProfileData()) {
1015       LoopInfo LI{DT};
1016       BranchProbabilityInfo BPI{F, LI};
1017       BFIPtr = std::make_unique<BlockFrequencyInfo>(F, BPI, LI);
1018       BFI = BFIPtr.get();
1019     }
1020 
1021     computeFunctionSummary(Index, M, F, BFI, PSI, DT,
1022                            !LocalsUsed.empty() || HasLocalInlineAsmSymbol,
1023                            CantBePromoted, IsThinLTO, GetSSICallback);
1024   }
1025 
1026   // Compute summaries for all variables defined in module, and save in the
1027   // index.
1028   SmallVector<MDNode *, 2> Types;
1029   for (const GlobalVariable &G : M.globals()) {
1030     if (G.isDeclaration())
1031       continue;
1032     computeVariableSummary(Index, G, CantBePromoted, M, Types);
1033   }
1034 
1035   // Compute summaries for all aliases defined in module, and save in the
1036   // index.
1037   for (const GlobalAlias &A : M.aliases())
1038     computeAliasSummary(Index, A, CantBePromoted);
1039 
1040   // Iterate through ifuncs, set their resolvers all alive.
1041   for (const GlobalIFunc &I : M.ifuncs()) {
1042     I.applyAlongResolverPath([&Index](const GlobalValue &GV) {
1043       Index.getGlobalValueSummary(GV)->setLive(true);
1044     });
1045   }
1046 
1047   for (auto *V : LocalsUsed) {
1048     auto *Summary = Index.getGlobalValueSummary(*V);
1049     assert(Summary && "Missing summary for global value");
1050     Summary->setNotEligibleToImport();
1051   }
1052 
1053   // The linker doesn't know about these LLVM produced values, so we need
1054   // to flag them as live in the index to ensure index-based dead value
1055   // analysis treats them as live roots of the analysis.
1056   setLiveRoot(Index, "llvm.used");
1057   setLiveRoot(Index, "llvm.compiler.used");
1058   setLiveRoot(Index, "llvm.global_ctors");
1059   setLiveRoot(Index, "llvm.global_dtors");
1060   setLiveRoot(Index, "llvm.global.annotations");
1061 
1062   for (auto &GlobalList : Index) {
1063     // Ignore entries for references that are undefined in the current module.
1064     if (GlobalList.second.SummaryList.empty())
1065       continue;
1066 
1067     assert(GlobalList.second.SummaryList.size() == 1 &&
1068            "Expected module's index to have one summary per GUID");
1069     auto &Summary = GlobalList.second.SummaryList[0];
1070     if (!IsThinLTO) {
1071       Summary->setNotEligibleToImport();
1072       continue;
1073     }
1074 
1075     bool AllRefsCanBeExternallyReferenced =
1076         llvm::all_of(Summary->refs(), [&](const ValueInfo &VI) {
1077           return !CantBePromoted.count(VI.getGUID());
1078         });
1079     if (!AllRefsCanBeExternallyReferenced) {
1080       Summary->setNotEligibleToImport();
1081       continue;
1082     }
1083 
1084     if (auto *FuncSummary = dyn_cast<FunctionSummary>(Summary.get())) {
1085       bool AllCallsCanBeExternallyReferenced = llvm::all_of(
1086           FuncSummary->calls(), [&](const FunctionSummary::EdgeTy &Edge) {
1087             return !CantBePromoted.count(Edge.first.getGUID());
1088           });
1089       if (!AllCallsCanBeExternallyReferenced)
1090         Summary->setNotEligibleToImport();
1091     }
1092   }
1093 
1094   if (!ModuleSummaryDotFile.empty()) {
1095     std::error_code EC;
1096     raw_fd_ostream OSDot(ModuleSummaryDotFile, EC, sys::fs::OpenFlags::OF_Text);
1097     if (EC)
1098       report_fatal_error(Twine("Failed to open dot file ") +
1099                          ModuleSummaryDotFile + ": " + EC.message() + "\n");
1100     Index.exportToDot(OSDot, {});
1101   }
1102 
1103   return Index;
1104 }
1105 
1106 AnalysisKey ModuleSummaryIndexAnalysis::Key;
1107 
1108 ModuleSummaryIndex
1109 ModuleSummaryIndexAnalysis::run(Module &M, ModuleAnalysisManager &AM) {
1110   ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
1111   auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
1112   bool NeedSSI = needsParamAccessSummary(M);
1113   return buildModuleSummaryIndex(
1114       M,
1115       [&FAM](const Function &F) {
1116         return &FAM.getResult<BlockFrequencyAnalysis>(
1117             *const_cast<Function *>(&F));
1118       },
1119       &PSI,
1120       [&FAM, NeedSSI](const Function &F) -> const StackSafetyInfo * {
1121         return NeedSSI ? &FAM.getResult<StackSafetyAnalysis>(
1122                              const_cast<Function &>(F))
1123                        : nullptr;
1124       });
1125 }
1126 
1127 char ModuleSummaryIndexWrapperPass::ID = 0;
1128 
1129 INITIALIZE_PASS_BEGIN(ModuleSummaryIndexWrapperPass, "module-summary-analysis",
1130                       "Module Summary Analysis", false, true)
1131 INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
1132 INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
1133 INITIALIZE_PASS_DEPENDENCY(StackSafetyInfoWrapperPass)
1134 INITIALIZE_PASS_END(ModuleSummaryIndexWrapperPass, "module-summary-analysis",
1135                     "Module Summary Analysis", false, true)
1136 
1137 ModulePass *llvm::createModuleSummaryIndexWrapperPass() {
1138   return new ModuleSummaryIndexWrapperPass();
1139 }
1140 
1141 ModuleSummaryIndexWrapperPass::ModuleSummaryIndexWrapperPass()
1142     : ModulePass(ID) {
1143   initializeModuleSummaryIndexWrapperPassPass(*PassRegistry::getPassRegistry());
1144 }
1145 
1146 bool ModuleSummaryIndexWrapperPass::runOnModule(Module &M) {
1147   auto *PSI = &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
1148   bool NeedSSI = needsParamAccessSummary(M);
1149   Index.emplace(buildModuleSummaryIndex(
1150       M,
1151       [this](const Function &F) {
1152         return &(this->getAnalysis<BlockFrequencyInfoWrapperPass>(
1153                          *const_cast<Function *>(&F))
1154                      .getBFI());
1155       },
1156       PSI,
1157       [&](const Function &F) -> const StackSafetyInfo * {
1158         return NeedSSI ? &getAnalysis<StackSafetyInfoWrapperPass>(
1159                               const_cast<Function &>(F))
1160                               .getResult()
1161                        : nullptr;
1162       }));
1163   return false;
1164 }
1165 
1166 bool ModuleSummaryIndexWrapperPass::doFinalization(Module &M) {
1167   Index.reset();
1168   return false;
1169 }
1170 
1171 void ModuleSummaryIndexWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
1172   AU.setPreservesAll();
1173   AU.addRequired<BlockFrequencyInfoWrapperPass>();
1174   AU.addRequired<ProfileSummaryInfoWrapperPass>();
1175   AU.addRequired<StackSafetyInfoWrapperPass>();
1176 }
1177 
1178 char ImmutableModuleSummaryIndexWrapperPass::ID = 0;
1179 
1180 ImmutableModuleSummaryIndexWrapperPass::ImmutableModuleSummaryIndexWrapperPass(
1181     const ModuleSummaryIndex *Index)
1182     : ImmutablePass(ID), Index(Index) {
1183   initializeImmutableModuleSummaryIndexWrapperPassPass(
1184       *PassRegistry::getPassRegistry());
1185 }
1186 
1187 void ImmutableModuleSummaryIndexWrapperPass::getAnalysisUsage(
1188     AnalysisUsage &AU) const {
1189   AU.setPreservesAll();
1190 }
1191 
1192 ImmutablePass *llvm::createImmutableModuleSummaryIndexWrapperPass(
1193     const ModuleSummaryIndex *Index) {
1194   return new ImmutableModuleSummaryIndexWrapperPass(Index);
1195 }
1196 
1197 INITIALIZE_PASS(ImmutableModuleSummaryIndexWrapperPass, "module-summary-info",
1198                 "Module summary info", false, true)
1199 
1200 bool llvm::mayHaveMemprofSummary(const CallBase *CB) {
1201   if (!CB)
1202     return false;
1203   if (CB->isDebugOrPseudoInst())
1204     return false;
1205   auto *CI = dyn_cast<CallInst>(CB);
1206   auto *CalledValue = CB->getCalledOperand();
1207   auto *CalledFunction = CB->getCalledFunction();
1208   if (CalledValue && !CalledFunction) {
1209     CalledValue = CalledValue->stripPointerCasts();
1210     // Stripping pointer casts can reveal a called function.
1211     CalledFunction = dyn_cast<Function>(CalledValue);
1212   }
1213   // Check if this is an alias to a function. If so, get the
1214   // called aliasee for the checks below.
1215   if (auto *GA = dyn_cast<GlobalAlias>(CalledValue)) {
1216     assert(!CalledFunction &&
1217            "Expected null called function in callsite for alias");
1218     CalledFunction = dyn_cast<Function>(GA->getAliaseeObject());
1219   }
1220   // Check if this is a direct call to a known function or a known
1221   // intrinsic, or an indirect call with profile data.
1222   if (CalledFunction) {
1223     if (CI && CalledFunction->isIntrinsic())
1224       return false;
1225   } else {
1226     // Skip inline assembly calls.
1227     if (CI && CI->isInlineAsm())
1228       return false;
1229     // Skip direct calls via Constant.
1230     if (!CalledValue || isa<Constant>(CalledValue))
1231       return false;
1232     return true;
1233   }
1234   return true;
1235 }
1236