xref: /freebsd/contrib/llvm-project/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp (revision 0fca6ea1d4eea4c934cfff25ac9ee8ad6fe95583)
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 extern cl::opt<bool> ScalePartialSampleProfileWorkingSetSize;
85 
86 extern cl::opt<unsigned> MaxNumVTableAnnotations;
87 
88 extern cl::opt<bool> MemProfReportHintedSizes;
89 
90 // Walk through the operands of a given User via worklist iteration and populate
91 // the set of GlobalValue references encountered. Invoked either on an
92 // Instruction or a GlobalVariable (which walks its initializer).
93 // Return true if any of the operands contains blockaddress. This is important
94 // to know when computing summary for global var, because if global variable
95 // references basic block address we can't import it separately from function
96 // containing that basic block. For simplicity we currently don't import such
97 // global vars at all. When importing function we aren't interested if any
98 // instruction in it takes an address of any basic block, because instruction
99 // can only take an address of basic block located in the same function.
100 // Set `RefLocalLinkageIFunc` to true if the analyzed value references a
101 // local-linkage ifunc.
findRefEdges(ModuleSummaryIndex & Index,const User * CurUser,SetVector<ValueInfo,std::vector<ValueInfo>> & RefEdges,SmallPtrSet<const User *,8> & Visited,bool & RefLocalLinkageIFunc)102 static bool findRefEdges(ModuleSummaryIndex &Index, const User *CurUser,
103                          SetVector<ValueInfo, std::vector<ValueInfo>> &RefEdges,
104                          SmallPtrSet<const User *, 8> &Visited,
105                          bool &RefLocalLinkageIFunc) {
106   bool HasBlockAddress = false;
107   SmallVector<const User *, 32> Worklist;
108   if (Visited.insert(CurUser).second)
109     Worklist.push_back(CurUser);
110 
111   while (!Worklist.empty()) {
112     const User *U = Worklist.pop_back_val();
113     const auto *CB = dyn_cast<CallBase>(U);
114 
115     for (const auto &OI : U->operands()) {
116       const User *Operand = dyn_cast<User>(OI);
117       if (!Operand)
118         continue;
119       if (isa<BlockAddress>(Operand)) {
120         HasBlockAddress = true;
121         continue;
122       }
123       if (auto *GV = dyn_cast<GlobalValue>(Operand)) {
124         // We have a reference to a global value. This should be added to
125         // the reference set unless it is a callee. Callees are handled
126         // specially by WriteFunction and are added to a separate list.
127         if (!(CB && CB->isCallee(&OI))) {
128           // If an ifunc has local linkage, do not add it into ref edges, and
129           // sets `RefLocalLinkageIFunc` to true. The referencer is not eligible
130           // for import. An ifunc doesn't have summary and ThinLTO cannot
131           // promote it; importing the referencer may cause linkage errors.
132           if (auto *GI = dyn_cast_if_present<GlobalIFunc>(GV);
133               GI && GI->hasLocalLinkage()) {
134             RefLocalLinkageIFunc = true;
135             continue;
136           }
137           RefEdges.insert(Index.getOrInsertValueInfo(GV));
138         }
139         continue;
140       }
141       if (Visited.insert(Operand).second)
142         Worklist.push_back(Operand);
143     }
144   }
145 
146   const Instruction *I = dyn_cast<Instruction>(CurUser);
147   if (I) {
148     uint64_t TotalCount = 0;
149     // MaxNumVTableAnnotations is the maximum number of vtables annotated on
150     // the instruction.
151     auto ValueDataArray = getValueProfDataFromInst(
152         *I, IPVK_VTableTarget, MaxNumVTableAnnotations, TotalCount);
153 
154     for (const auto &V : ValueDataArray)
155       RefEdges.insert(Index.getOrInsertValueInfo(/* VTableGUID = */
156                                                  V.Value));
157   }
158   return HasBlockAddress;
159 }
160 
getHotness(uint64_t ProfileCount,ProfileSummaryInfo * PSI)161 static CalleeInfo::HotnessType getHotness(uint64_t ProfileCount,
162                                           ProfileSummaryInfo *PSI) {
163   if (!PSI)
164     return CalleeInfo::HotnessType::Unknown;
165   if (PSI->isHotCount(ProfileCount))
166     return CalleeInfo::HotnessType::Hot;
167   if (PSI->isColdCount(ProfileCount))
168     return CalleeInfo::HotnessType::Cold;
169   return CalleeInfo::HotnessType::None;
170 }
171 
isNonRenamableLocal(const GlobalValue & GV)172 static bool isNonRenamableLocal(const GlobalValue &GV) {
173   return GV.hasSection() && GV.hasLocalLinkage();
174 }
175 
176 /// Determine whether this call has all constant integer arguments (excluding
177 /// "this") and summarize it to VCalls or ConstVCalls as appropriate.
addVCallToSet(DevirtCallSite Call,GlobalValue::GUID Guid,SetVector<FunctionSummary::VFuncId,std::vector<FunctionSummary::VFuncId>> & VCalls,SetVector<FunctionSummary::ConstVCall,std::vector<FunctionSummary::ConstVCall>> & ConstVCalls)178 static void addVCallToSet(
179     DevirtCallSite Call, GlobalValue::GUID Guid,
180     SetVector<FunctionSummary::VFuncId, std::vector<FunctionSummary::VFuncId>>
181         &VCalls,
182     SetVector<FunctionSummary::ConstVCall,
183               std::vector<FunctionSummary::ConstVCall>> &ConstVCalls) {
184   std::vector<uint64_t> Args;
185   // Start from the second argument to skip the "this" pointer.
186   for (auto &Arg : drop_begin(Call.CB.args())) {
187     auto *CI = dyn_cast<ConstantInt>(Arg);
188     if (!CI || CI->getBitWidth() > 64) {
189       VCalls.insert({Guid, Call.Offset});
190       return;
191     }
192     Args.push_back(CI->getZExtValue());
193   }
194   ConstVCalls.insert({{Guid, Call.Offset}, std::move(Args)});
195 }
196 
197 /// If this intrinsic call requires that we add information to the function
198 /// summary, do so via the non-constant reference arguments.
addIntrinsicToSummary(const CallInst * CI,SetVector<GlobalValue::GUID,std::vector<GlobalValue::GUID>> & TypeTests,SetVector<FunctionSummary::VFuncId,std::vector<FunctionSummary::VFuncId>> & TypeTestAssumeVCalls,SetVector<FunctionSummary::VFuncId,std::vector<FunctionSummary::VFuncId>> & TypeCheckedLoadVCalls,SetVector<FunctionSummary::ConstVCall,std::vector<FunctionSummary::ConstVCall>> & TypeTestAssumeConstVCalls,SetVector<FunctionSummary::ConstVCall,std::vector<FunctionSummary::ConstVCall>> & TypeCheckedLoadConstVCalls,DominatorTree & DT)199 static void addIntrinsicToSummary(
200     const CallInst *CI,
201     SetVector<GlobalValue::GUID, std::vector<GlobalValue::GUID>> &TypeTests,
202     SetVector<FunctionSummary::VFuncId, std::vector<FunctionSummary::VFuncId>>
203         &TypeTestAssumeVCalls,
204     SetVector<FunctionSummary::VFuncId, std::vector<FunctionSummary::VFuncId>>
205         &TypeCheckedLoadVCalls,
206     SetVector<FunctionSummary::ConstVCall,
207               std::vector<FunctionSummary::ConstVCall>>
208         &TypeTestAssumeConstVCalls,
209     SetVector<FunctionSummary::ConstVCall,
210               std::vector<FunctionSummary::ConstVCall>>
211         &TypeCheckedLoadConstVCalls,
212     DominatorTree &DT) {
213   switch (CI->getCalledFunction()->getIntrinsicID()) {
214   case Intrinsic::type_test:
215   case Intrinsic::public_type_test: {
216     auto *TypeMDVal = cast<MetadataAsValue>(CI->getArgOperand(1));
217     auto *TypeId = dyn_cast<MDString>(TypeMDVal->getMetadata());
218     if (!TypeId)
219       break;
220     GlobalValue::GUID Guid = GlobalValue::getGUID(TypeId->getString());
221 
222     // Produce a summary from type.test intrinsics. We only summarize type.test
223     // intrinsics that are used other than by an llvm.assume intrinsic.
224     // Intrinsics that are assumed are relevant only to the devirtualization
225     // pass, not the type test lowering pass.
226     bool HasNonAssumeUses = llvm::any_of(CI->uses(), [](const Use &CIU) {
227       return !isa<AssumeInst>(CIU.getUser());
228     });
229     if (HasNonAssumeUses)
230       TypeTests.insert(Guid);
231 
232     SmallVector<DevirtCallSite, 4> DevirtCalls;
233     SmallVector<CallInst *, 4> Assumes;
234     findDevirtualizableCallsForTypeTest(DevirtCalls, Assumes, CI, DT);
235     for (auto &Call : DevirtCalls)
236       addVCallToSet(Call, Guid, TypeTestAssumeVCalls,
237                     TypeTestAssumeConstVCalls);
238 
239     break;
240   }
241 
242   case Intrinsic::type_checked_load_relative:
243   case Intrinsic::type_checked_load: {
244     auto *TypeMDVal = cast<MetadataAsValue>(CI->getArgOperand(2));
245     auto *TypeId = dyn_cast<MDString>(TypeMDVal->getMetadata());
246     if (!TypeId)
247       break;
248     GlobalValue::GUID Guid = GlobalValue::getGUID(TypeId->getString());
249 
250     SmallVector<DevirtCallSite, 4> DevirtCalls;
251     SmallVector<Instruction *, 4> LoadedPtrs;
252     SmallVector<Instruction *, 4> Preds;
253     bool HasNonCallUses = false;
254     findDevirtualizableCallsForTypeCheckedLoad(DevirtCalls, LoadedPtrs, Preds,
255                                                HasNonCallUses, CI, DT);
256     // Any non-call uses of the result of llvm.type.checked.load will
257     // prevent us from optimizing away the llvm.type.test.
258     if (HasNonCallUses)
259       TypeTests.insert(Guid);
260     for (auto &Call : DevirtCalls)
261       addVCallToSet(Call, Guid, TypeCheckedLoadVCalls,
262                     TypeCheckedLoadConstVCalls);
263 
264     break;
265   }
266   default:
267     break;
268   }
269 }
270 
isNonVolatileLoad(const Instruction * I)271 static bool isNonVolatileLoad(const Instruction *I) {
272   if (const auto *LI = dyn_cast<LoadInst>(I))
273     return !LI->isVolatile();
274 
275   return false;
276 }
277 
isNonVolatileStore(const Instruction * I)278 static bool isNonVolatileStore(const Instruction *I) {
279   if (const auto *SI = dyn_cast<StoreInst>(I))
280     return !SI->isVolatile();
281 
282   return false;
283 }
284 
285 // Returns true if the function definition must be unreachable.
286 //
287 // Note if this helper function returns true, `F` is guaranteed
288 // to be unreachable; if it returns false, `F` might still
289 // be unreachable but not covered by this helper function.
mustBeUnreachableFunction(const Function & F)290 static bool mustBeUnreachableFunction(const Function &F) {
291   // A function must be unreachable if its entry block ends with an
292   // 'unreachable'.
293   assert(!F.isDeclaration());
294   return isa<UnreachableInst>(F.getEntryBlock().getTerminator());
295 }
296 
computeFunctionSummary(ModuleSummaryIndex & Index,const Module & M,const Function & F,BlockFrequencyInfo * BFI,ProfileSummaryInfo * PSI,DominatorTree & DT,bool HasLocalsInUsedOrAsm,DenseSet<GlobalValue::GUID> & CantBePromoted,bool IsThinLTO,std::function<const StackSafetyInfo * (const Function & F)> GetSSICallback)297 static void computeFunctionSummary(
298     ModuleSummaryIndex &Index, const Module &M, const Function &F,
299     BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI, DominatorTree &DT,
300     bool HasLocalsInUsedOrAsm, DenseSet<GlobalValue::GUID> &CantBePromoted,
301     bool IsThinLTO,
302     std::function<const StackSafetyInfo *(const Function &F)> GetSSICallback) {
303   // Summary not currently supported for anonymous functions, they should
304   // have been named.
305   assert(F.hasName());
306 
307   unsigned NumInsts = 0;
308   // Map from callee ValueId to profile count. Used to accumulate profile
309   // counts for all static calls to a given callee.
310   MapVector<ValueInfo, CalleeInfo, DenseMap<ValueInfo, unsigned>,
311             std::vector<std::pair<ValueInfo, CalleeInfo>>>
312       CallGraphEdges;
313   SetVector<ValueInfo, std::vector<ValueInfo>> RefEdges, LoadRefEdges,
314       StoreRefEdges;
315   SetVector<GlobalValue::GUID, std::vector<GlobalValue::GUID>> TypeTests;
316   SetVector<FunctionSummary::VFuncId, std::vector<FunctionSummary::VFuncId>>
317       TypeTestAssumeVCalls, TypeCheckedLoadVCalls;
318   SetVector<FunctionSummary::ConstVCall,
319             std::vector<FunctionSummary::ConstVCall>>
320       TypeTestAssumeConstVCalls, TypeCheckedLoadConstVCalls;
321   ICallPromotionAnalysis ICallAnalysis;
322   SmallPtrSet<const User *, 8> Visited;
323 
324   // Add personality function, prefix data and prologue data to function's ref
325   // list.
326   bool HasLocalIFuncCallOrRef = false;
327   findRefEdges(Index, &F, RefEdges, Visited, HasLocalIFuncCallOrRef);
328   std::vector<const Instruction *> NonVolatileLoads;
329   std::vector<const Instruction *> NonVolatileStores;
330 
331   std::vector<CallsiteInfo> Callsites;
332   std::vector<AllocInfo> Allocs;
333 
334 #ifndef NDEBUG
335   DenseSet<const CallBase *> CallsThatMayHaveMemprofSummary;
336 #endif
337 
338   bool HasInlineAsmMaybeReferencingInternal = false;
339   bool HasIndirBranchToBlockAddress = false;
340   bool HasUnknownCall = false;
341   bool MayThrow = false;
342   for (const BasicBlock &BB : F) {
343     // We don't allow inlining of function with indirect branch to blockaddress.
344     // If the blockaddress escapes the function, e.g., via a global variable,
345     // inlining may lead to an invalid cross-function reference. So we shouldn't
346     // import such function either.
347     if (BB.hasAddressTaken()) {
348       for (User *U : BlockAddress::get(const_cast<BasicBlock *>(&BB))->users())
349         if (!isa<CallBrInst>(*U)) {
350           HasIndirBranchToBlockAddress = true;
351           break;
352         }
353     }
354 
355     for (const Instruction &I : BB) {
356       if (I.isDebugOrPseudoInst())
357         continue;
358       ++NumInsts;
359 
360       // Regular LTO module doesn't participate in ThinLTO import,
361       // so no reference from it can be read/writeonly, since this
362       // would require importing variable as local copy
363       if (IsThinLTO) {
364         if (isNonVolatileLoad(&I)) {
365           // Postpone processing of non-volatile load instructions
366           // See comments below
367           Visited.insert(&I);
368           NonVolatileLoads.push_back(&I);
369           continue;
370         } else if (isNonVolatileStore(&I)) {
371           Visited.insert(&I);
372           NonVolatileStores.push_back(&I);
373           // All references from second operand of store (destination address)
374           // can be considered write-only if they're not referenced by any
375           // non-store instruction. References from first operand of store
376           // (stored value) can't be treated either as read- or as write-only
377           // so we add them to RefEdges as we do with all other instructions
378           // except non-volatile load.
379           Value *Stored = I.getOperand(0);
380           if (auto *GV = dyn_cast<GlobalValue>(Stored))
381             // findRefEdges will try to examine GV operands, so instead
382             // of calling it we should add GV to RefEdges directly.
383             RefEdges.insert(Index.getOrInsertValueInfo(GV));
384           else if (auto *U = dyn_cast<User>(Stored))
385             findRefEdges(Index, U, RefEdges, Visited, HasLocalIFuncCallOrRef);
386           continue;
387         }
388       }
389       findRefEdges(Index, &I, RefEdges, Visited, HasLocalIFuncCallOrRef);
390       const auto *CB = dyn_cast<CallBase>(&I);
391       if (!CB) {
392         if (I.mayThrow())
393           MayThrow = true;
394         continue;
395       }
396 
397       const auto *CI = dyn_cast<CallInst>(&I);
398       // Since we don't know exactly which local values are referenced in inline
399       // assembly, conservatively mark the function as possibly referencing
400       // a local value from inline assembly to ensure we don't export a
401       // reference (which would require renaming and promotion of the
402       // referenced value).
403       if (HasLocalsInUsedOrAsm && CI && CI->isInlineAsm())
404         HasInlineAsmMaybeReferencingInternal = true;
405 
406       auto *CalledValue = CB->getCalledOperand();
407       auto *CalledFunction = CB->getCalledFunction();
408       if (CalledValue && !CalledFunction) {
409         CalledValue = CalledValue->stripPointerCasts();
410         // Stripping pointer casts can reveal a called function.
411         CalledFunction = dyn_cast<Function>(CalledValue);
412       }
413       // Check if this is an alias to a function. If so, get the
414       // called aliasee for the checks below.
415       if (auto *GA = dyn_cast<GlobalAlias>(CalledValue)) {
416         assert(!CalledFunction && "Expected null called function in callsite for alias");
417         CalledFunction = dyn_cast<Function>(GA->getAliaseeObject());
418       }
419       // Check if this is a direct call to a known function or a known
420       // intrinsic, or an indirect call with profile data.
421       if (CalledFunction) {
422         if (CI && CalledFunction->isIntrinsic()) {
423           addIntrinsicToSummary(
424               CI, TypeTests, TypeTestAssumeVCalls, TypeCheckedLoadVCalls,
425               TypeTestAssumeConstVCalls, TypeCheckedLoadConstVCalls, DT);
426           continue;
427         }
428         // We should have named any anonymous globals
429         assert(CalledFunction->hasName());
430         auto ScaledCount = PSI->getProfileCount(*CB, BFI);
431         auto Hotness = ScaledCount ? getHotness(*ScaledCount, PSI)
432                                    : CalleeInfo::HotnessType::Unknown;
433         if (ForceSummaryEdgesCold != FunctionSummary::FSHT_None)
434           Hotness = CalleeInfo::HotnessType::Cold;
435 
436         // Use the original CalledValue, in case it was an alias. We want
437         // to record the call edge to the alias in that case. Eventually
438         // an alias summary will be created to associate the alias and
439         // aliasee.
440         auto &ValueInfo = CallGraphEdges[Index.getOrInsertValueInfo(
441             cast<GlobalValue>(CalledValue))];
442         ValueInfo.updateHotness(Hotness);
443         if (CB->isTailCall())
444           ValueInfo.setHasTailCall(true);
445         // Add the relative block frequency to CalleeInfo if there is no profile
446         // information.
447         if (BFI != nullptr && Hotness == CalleeInfo::HotnessType::Unknown) {
448           uint64_t BBFreq = BFI->getBlockFreq(&BB).getFrequency();
449           uint64_t EntryFreq = BFI->getEntryFreq().getFrequency();
450           ValueInfo.updateRelBlockFreq(BBFreq, EntryFreq);
451         }
452       } else {
453         HasUnknownCall = true;
454         // If F is imported, a local linkage ifunc (e.g. target_clones on a
455         // static function) called by F will be cloned. Since summaries don't
456         // track ifunc, we do not know implementation functions referenced by
457         // the ifunc resolver need to be promoted in the exporter, and we will
458         // get linker errors due to cloned declarations for implementation
459         // functions. As a simple fix, just mark F as not eligible for import.
460         // Non-local ifunc is not cloned and does not have the issue.
461         if (auto *GI = dyn_cast_if_present<GlobalIFunc>(CalledValue))
462           if (GI->hasLocalLinkage())
463             HasLocalIFuncCallOrRef = true;
464         // Skip inline assembly calls.
465         if (CI && CI->isInlineAsm())
466           continue;
467         // Skip direct calls.
468         if (!CalledValue || isa<Constant>(CalledValue))
469           continue;
470 
471         // Check if the instruction has a callees metadata. If so, add callees
472         // to CallGraphEdges to reflect the references from the metadata, and
473         // to enable importing for subsequent indirect call promotion and
474         // inlining.
475         if (auto *MD = I.getMetadata(LLVMContext::MD_callees)) {
476           for (const auto &Op : MD->operands()) {
477             Function *Callee = mdconst::extract_or_null<Function>(Op);
478             if (Callee)
479               CallGraphEdges[Index.getOrInsertValueInfo(Callee)];
480           }
481         }
482 
483         uint32_t NumCandidates;
484         uint64_t TotalCount;
485         auto CandidateProfileData =
486             ICallAnalysis.getPromotionCandidatesForInstruction(&I, TotalCount,
487                                                                NumCandidates);
488         for (const auto &Candidate : CandidateProfileData)
489           CallGraphEdges[Index.getOrInsertValueInfo(Candidate.Value)]
490               .updateHotness(getHotness(Candidate.Count, PSI));
491       }
492 
493       // Summarize memprof related metadata. This is only needed for ThinLTO.
494       if (!IsThinLTO)
495         continue;
496 
497       // TODO: Skip indirect calls for now. Need to handle these better, likely
498       // by creating multiple Callsites, one per target, then speculatively
499       // devirtualize while applying clone info in the ThinLTO backends. This
500       // will also be important because we will have a different set of clone
501       // versions per target. This handling needs to match that in the ThinLTO
502       // backend so we handle things consistently for matching of callsite
503       // summaries to instructions.
504       if (!CalledFunction)
505         continue;
506 
507       // Ensure we keep this analysis in sync with the handling in the ThinLTO
508       // backend (see MemProfContextDisambiguation::applyImport). Save this call
509       // so that we can skip it in checking the reverse case later.
510       assert(mayHaveMemprofSummary(CB));
511 #ifndef NDEBUG
512       CallsThatMayHaveMemprofSummary.insert(CB);
513 #endif
514 
515       // Compute the list of stack ids first (so we can trim them from the stack
516       // ids on any MIBs).
517       CallStack<MDNode, MDNode::op_iterator> InstCallsite(
518           I.getMetadata(LLVMContext::MD_callsite));
519       auto *MemProfMD = I.getMetadata(LLVMContext::MD_memprof);
520       if (MemProfMD) {
521         std::vector<MIBInfo> MIBs;
522         std::vector<uint64_t> TotalSizes;
523         for (auto &MDOp : MemProfMD->operands()) {
524           auto *MIBMD = cast<const MDNode>(MDOp);
525           MDNode *StackNode = getMIBStackNode(MIBMD);
526           assert(StackNode);
527           SmallVector<unsigned> StackIdIndices;
528           CallStack<MDNode, MDNode::op_iterator> StackContext(StackNode);
529           // Collapse out any on the allocation call (inlining).
530           for (auto ContextIter =
531                    StackContext.beginAfterSharedPrefix(InstCallsite);
532                ContextIter != StackContext.end(); ++ContextIter) {
533             unsigned StackIdIdx = Index.addOrGetStackIdIndex(*ContextIter);
534             // If this is a direct recursion, simply skip the duplicate
535             // entries. If this is mutual recursion, handling is left to
536             // the LTO link analysis client.
537             if (StackIdIndices.empty() || StackIdIndices.back() != StackIdIdx)
538               StackIdIndices.push_back(StackIdIdx);
539           }
540           MIBs.push_back(
541               MIBInfo(getMIBAllocType(MIBMD), std::move(StackIdIndices)));
542           if (MemProfReportHintedSizes) {
543             auto TotalSize = getMIBTotalSize(MIBMD);
544             assert(TotalSize);
545             TotalSizes.push_back(TotalSize);
546           }
547         }
548         Allocs.push_back(AllocInfo(std::move(MIBs)));
549         if (MemProfReportHintedSizes) {
550           assert(Allocs.back().MIBs.size() == TotalSizes.size());
551           Allocs.back().TotalSizes = std::move(TotalSizes);
552         }
553       } else if (!InstCallsite.empty()) {
554         SmallVector<unsigned> StackIdIndices;
555         for (auto StackId : InstCallsite)
556           StackIdIndices.push_back(Index.addOrGetStackIdIndex(StackId));
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       }
565     }
566   }
567 
568   if (PSI->hasPartialSampleProfile() && ScalePartialSampleProfileWorkingSetSize)
569     Index.addBlockCount(F.size());
570 
571   std::vector<ValueInfo> Refs;
572   if (IsThinLTO) {
573     auto AddRefEdges = [&](const std::vector<const Instruction *> &Instrs,
574                            SetVector<ValueInfo, std::vector<ValueInfo>> &Edges,
575                            SmallPtrSet<const User *, 8> &Cache) {
576       for (const auto *I : Instrs) {
577         Cache.erase(I);
578         findRefEdges(Index, I, Edges, Cache, HasLocalIFuncCallOrRef);
579       }
580     };
581 
582     // By now we processed all instructions in a function, except
583     // non-volatile loads and non-volatile value stores. Let's find
584     // ref edges for both of instruction sets
585     AddRefEdges(NonVolatileLoads, LoadRefEdges, Visited);
586     // We can add some values to the Visited set when processing load
587     // instructions which are also used by stores in NonVolatileStores.
588     // For example this can happen if we have following code:
589     //
590     // store %Derived* @foo, %Derived** bitcast (%Base** @bar to %Derived**)
591     // %42 = load %Derived*, %Derived** bitcast (%Base** @bar to %Derived**)
592     //
593     // After processing loads we'll add bitcast to the Visited set, and if
594     // we use the same set while processing stores, we'll never see store
595     // to @bar and @bar will be mistakenly treated as readonly.
596     SmallPtrSet<const llvm::User *, 8> StoreCache;
597     AddRefEdges(NonVolatileStores, StoreRefEdges, StoreCache);
598 
599     // If both load and store instruction reference the same variable
600     // we won't be able to optimize it. Add all such reference edges
601     // to RefEdges set.
602     for (const auto &VI : StoreRefEdges)
603       if (LoadRefEdges.remove(VI))
604         RefEdges.insert(VI);
605 
606     unsigned RefCnt = RefEdges.size();
607     // All new reference edges inserted in two loops below are either
608     // read or write only. They will be grouped in the end of RefEdges
609     // vector, so we can use a single integer value to identify them.
610     for (const auto &VI : LoadRefEdges)
611       RefEdges.insert(VI);
612 
613     unsigned FirstWORef = RefEdges.size();
614     for (const auto &VI : StoreRefEdges)
615       RefEdges.insert(VI);
616 
617     Refs = RefEdges.takeVector();
618     for (; RefCnt < FirstWORef; ++RefCnt)
619       Refs[RefCnt].setReadOnly();
620 
621     for (; RefCnt < Refs.size(); ++RefCnt)
622       Refs[RefCnt].setWriteOnly();
623   } else {
624     Refs = RefEdges.takeVector();
625   }
626   // Explicit add hot edges to enforce importing for designated GUIDs for
627   // sample PGO, to enable the same inlines as the profiled optimized binary.
628   for (auto &I : F.getImportGUIDs())
629     CallGraphEdges[Index.getOrInsertValueInfo(I)].updateHotness(
630         ForceSummaryEdgesCold == FunctionSummary::FSHT_All
631             ? CalleeInfo::HotnessType::Cold
632             : CalleeInfo::HotnessType::Critical);
633 
634 #ifndef NDEBUG
635   // Make sure that all calls we decided could not have memprof summaries get a
636   // false value for mayHaveMemprofSummary, to ensure that this handling remains
637   // in sync with the ThinLTO backend handling.
638   if (IsThinLTO) {
639     for (const BasicBlock &BB : F) {
640       for (const Instruction &I : BB) {
641         const auto *CB = dyn_cast<CallBase>(&I);
642         if (!CB)
643           continue;
644         // We already checked these above.
645         if (CallsThatMayHaveMemprofSummary.count(CB))
646           continue;
647         assert(!mayHaveMemprofSummary(CB));
648       }
649     }
650   }
651 #endif
652 
653   bool NonRenamableLocal = isNonRenamableLocal(F);
654   bool NotEligibleForImport =
655       NonRenamableLocal || HasInlineAsmMaybeReferencingInternal ||
656       HasIndirBranchToBlockAddress || HasLocalIFuncCallOrRef;
657   GlobalValueSummary::GVFlags Flags(
658       F.getLinkage(), F.getVisibility(), NotEligibleForImport,
659       /* Live = */ false, F.isDSOLocal(), F.canBeOmittedFromSymbolTable(),
660       GlobalValueSummary::ImportKind::Definition);
661   FunctionSummary::FFlags FunFlags{
662       F.doesNotAccessMemory(), F.onlyReadsMemory() && !F.doesNotAccessMemory(),
663       F.hasFnAttribute(Attribute::NoRecurse), F.returnDoesNotAlias(),
664       // FIXME: refactor this to use the same code that inliner is using.
665       // Don't try to import functions with noinline attribute.
666       F.getAttributes().hasFnAttr(Attribute::NoInline),
667       F.hasFnAttribute(Attribute::AlwaysInline),
668       F.hasFnAttribute(Attribute::NoUnwind), MayThrow, HasUnknownCall,
669       mustBeUnreachableFunction(F)};
670   std::vector<FunctionSummary::ParamAccess> ParamAccesses;
671   if (auto *SSI = GetSSICallback(F))
672     ParamAccesses = SSI->getParamAccesses(Index);
673   auto FuncSummary = std::make_unique<FunctionSummary>(
674       Flags, NumInsts, FunFlags, /*EntryCount=*/0, std::move(Refs),
675       CallGraphEdges.takeVector(), TypeTests.takeVector(),
676       TypeTestAssumeVCalls.takeVector(), TypeCheckedLoadVCalls.takeVector(),
677       TypeTestAssumeConstVCalls.takeVector(),
678       TypeCheckedLoadConstVCalls.takeVector(), std::move(ParamAccesses),
679       std::move(Callsites), std::move(Allocs));
680   if (NonRenamableLocal)
681     CantBePromoted.insert(F.getGUID());
682   Index.addGlobalValueSummary(F, std::move(FuncSummary));
683 }
684 
685 /// Find function pointers referenced within the given vtable initializer
686 /// (or subset of an initializer) \p I. The starting offset of \p I within
687 /// the vtable initializer is \p StartingOffset. Any discovered function
688 /// pointers are added to \p VTableFuncs along with their cumulative offset
689 /// within the initializer.
findFuncPointers(const Constant * I,uint64_t StartingOffset,const Module & M,ModuleSummaryIndex & Index,VTableFuncList & VTableFuncs,const GlobalVariable & OrigGV)690 static void findFuncPointers(const Constant *I, uint64_t StartingOffset,
691                              const Module &M, ModuleSummaryIndex &Index,
692                              VTableFuncList &VTableFuncs,
693                              const GlobalVariable &OrigGV) {
694   // First check if this is a function pointer.
695   if (I->getType()->isPointerTy()) {
696     auto C = I->stripPointerCasts();
697     auto A = dyn_cast<GlobalAlias>(C);
698     if (isa<Function>(C) || (A && isa<Function>(A->getAliasee()))) {
699       auto GV = dyn_cast<GlobalValue>(C);
700       assert(GV);
701       // We can disregard __cxa_pure_virtual as a possible call target, as
702       // calls to pure virtuals are UB.
703       if (GV && GV->getName() != "__cxa_pure_virtual")
704         VTableFuncs.push_back({Index.getOrInsertValueInfo(GV), StartingOffset});
705       return;
706     }
707   }
708 
709   // Walk through the elements in the constant struct or array and recursively
710   // look for virtual function pointers.
711   const DataLayout &DL = M.getDataLayout();
712   if (auto *C = dyn_cast<ConstantStruct>(I)) {
713     StructType *STy = dyn_cast<StructType>(C->getType());
714     assert(STy);
715     const StructLayout *SL = DL.getStructLayout(C->getType());
716 
717     for (auto EI : llvm::enumerate(STy->elements())) {
718       auto Offset = SL->getElementOffset(EI.index());
719       unsigned Op = SL->getElementContainingOffset(Offset);
720       findFuncPointers(cast<Constant>(I->getOperand(Op)),
721                        StartingOffset + Offset, M, Index, VTableFuncs, OrigGV);
722     }
723   } else if (auto *C = dyn_cast<ConstantArray>(I)) {
724     ArrayType *ATy = C->getType();
725     Type *EltTy = ATy->getElementType();
726     uint64_t EltSize = DL.getTypeAllocSize(EltTy);
727     for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) {
728       findFuncPointers(cast<Constant>(I->getOperand(i)),
729                        StartingOffset + i * EltSize, M, Index, VTableFuncs,
730                        OrigGV);
731     }
732   } else if (const auto *CE = dyn_cast<ConstantExpr>(I)) {
733     // For relative vtables, the next sub-component should be a trunc.
734     if (CE->getOpcode() != Instruction::Trunc ||
735         !(CE = dyn_cast<ConstantExpr>(CE->getOperand(0))))
736       return;
737 
738     // If this constant can be reduced to the offset between a function and a
739     // global, then we know this is a valid virtual function if the RHS is the
740     // original vtable we're scanning through.
741     if (CE->getOpcode() == Instruction::Sub) {
742       GlobalValue *LHS, *RHS;
743       APSInt LHSOffset, RHSOffset;
744       if (IsConstantOffsetFromGlobal(CE->getOperand(0), LHS, LHSOffset, DL) &&
745           IsConstantOffsetFromGlobal(CE->getOperand(1), RHS, RHSOffset, DL) &&
746           RHS == &OrigGV &&
747 
748           // For relative vtables, this component should point to the callable
749           // function without any offsets.
750           LHSOffset == 0 &&
751 
752           // Also, the RHS should always point to somewhere within the vtable.
753           RHSOffset <=
754               static_cast<uint64_t>(DL.getTypeAllocSize(OrigGV.getInitializer()->getType()))) {
755         findFuncPointers(LHS, StartingOffset, M, Index, VTableFuncs, OrigGV);
756       }
757     }
758   }
759 }
760 
761 // Identify the function pointers referenced by vtable definition \p V.
computeVTableFuncs(ModuleSummaryIndex & Index,const GlobalVariable & V,const Module & M,VTableFuncList & VTableFuncs)762 static void computeVTableFuncs(ModuleSummaryIndex &Index,
763                                const GlobalVariable &V, const Module &M,
764                                VTableFuncList &VTableFuncs) {
765   if (!V.isConstant())
766     return;
767 
768   findFuncPointers(V.getInitializer(), /*StartingOffset=*/0, M, Index,
769                    VTableFuncs, V);
770 
771 #ifndef NDEBUG
772   // Validate that the VTableFuncs list is ordered by offset.
773   uint64_t PrevOffset = 0;
774   for (auto &P : VTableFuncs) {
775     // The findVFuncPointers traversal should have encountered the
776     // functions in offset order. We need to use ">=" since PrevOffset
777     // starts at 0.
778     assert(P.VTableOffset >= PrevOffset);
779     PrevOffset = P.VTableOffset;
780   }
781 #endif
782 }
783 
784 /// Record vtable definition \p V for each type metadata it references.
785 static void
recordTypeIdCompatibleVtableReferences(ModuleSummaryIndex & Index,const GlobalVariable & V,SmallVectorImpl<MDNode * > & Types)786 recordTypeIdCompatibleVtableReferences(ModuleSummaryIndex &Index,
787                                        const GlobalVariable &V,
788                                        SmallVectorImpl<MDNode *> &Types) {
789   for (MDNode *Type : Types) {
790     auto TypeID = Type->getOperand(1).get();
791 
792     uint64_t Offset =
793         cast<ConstantInt>(
794             cast<ConstantAsMetadata>(Type->getOperand(0))->getValue())
795             ->getZExtValue();
796 
797     if (auto *TypeId = dyn_cast<MDString>(TypeID))
798       Index.getOrInsertTypeIdCompatibleVtableSummary(TypeId->getString())
799           .push_back({Offset, Index.getOrInsertValueInfo(&V)});
800   }
801 }
802 
computeVariableSummary(ModuleSummaryIndex & Index,const GlobalVariable & V,DenseSet<GlobalValue::GUID> & CantBePromoted,const Module & M,SmallVectorImpl<MDNode * > & Types)803 static void computeVariableSummary(ModuleSummaryIndex &Index,
804                                    const GlobalVariable &V,
805                                    DenseSet<GlobalValue::GUID> &CantBePromoted,
806                                    const Module &M,
807                                    SmallVectorImpl<MDNode *> &Types) {
808   SetVector<ValueInfo, std::vector<ValueInfo>> RefEdges;
809   SmallPtrSet<const User *, 8> Visited;
810   bool RefLocalIFunc = false;
811   bool HasBlockAddress =
812       findRefEdges(Index, &V, RefEdges, Visited, RefLocalIFunc);
813   const bool NotEligibleForImport = (HasBlockAddress || RefLocalIFunc);
814   bool NonRenamableLocal = isNonRenamableLocal(V);
815   GlobalValueSummary::GVFlags Flags(
816       V.getLinkage(), V.getVisibility(), NonRenamableLocal,
817       /* Live = */ false, V.isDSOLocal(), V.canBeOmittedFromSymbolTable(),
818       GlobalValueSummary::Definition);
819 
820   VTableFuncList VTableFuncs;
821   // If splitting is not enabled, then we compute the summary information
822   // necessary for index-based whole program devirtualization.
823   if (!Index.enableSplitLTOUnit()) {
824     Types.clear();
825     V.getMetadata(LLVMContext::MD_type, Types);
826     if (!Types.empty()) {
827       // Identify the function pointers referenced by this vtable definition.
828       computeVTableFuncs(Index, V, M, VTableFuncs);
829 
830       // Record this vtable definition for each type metadata it references.
831       recordTypeIdCompatibleVtableReferences(Index, V, Types);
832     }
833   }
834 
835   // Don't mark variables we won't be able to internalize as read/write-only.
836   bool CanBeInternalized =
837       !V.hasComdat() && !V.hasAppendingLinkage() && !V.isInterposable() &&
838       !V.hasAvailableExternallyLinkage() && !V.hasDLLExportStorageClass();
839   bool Constant = V.isConstant();
840   GlobalVarSummary::GVarFlags VarFlags(CanBeInternalized,
841                                        Constant ? false : CanBeInternalized,
842                                        Constant, V.getVCallVisibility());
843   auto GVarSummary = std::make_unique<GlobalVarSummary>(Flags, VarFlags,
844                                                          RefEdges.takeVector());
845   if (NonRenamableLocal)
846     CantBePromoted.insert(V.getGUID());
847   if (NotEligibleForImport)
848     GVarSummary->setNotEligibleToImport();
849   if (!VTableFuncs.empty())
850     GVarSummary->setVTableFuncs(VTableFuncs);
851   Index.addGlobalValueSummary(V, std::move(GVarSummary));
852 }
853 
computeAliasSummary(ModuleSummaryIndex & Index,const GlobalAlias & A,DenseSet<GlobalValue::GUID> & CantBePromoted)854 static void computeAliasSummary(ModuleSummaryIndex &Index, const GlobalAlias &A,
855                                 DenseSet<GlobalValue::GUID> &CantBePromoted) {
856   // Skip summary for indirect function aliases as summary for aliasee will not
857   // be emitted.
858   const GlobalObject *Aliasee = A.getAliaseeObject();
859   if (isa<GlobalIFunc>(Aliasee))
860     return;
861   bool NonRenamableLocal = isNonRenamableLocal(A);
862   GlobalValueSummary::GVFlags Flags(
863       A.getLinkage(), A.getVisibility(), NonRenamableLocal,
864       /* Live = */ false, A.isDSOLocal(), A.canBeOmittedFromSymbolTable(),
865       GlobalValueSummary::Definition);
866   auto AS = std::make_unique<AliasSummary>(Flags);
867   auto AliaseeVI = Index.getValueInfo(Aliasee->getGUID());
868   assert(AliaseeVI && "Alias expects aliasee summary to be available");
869   assert(AliaseeVI.getSummaryList().size() == 1 &&
870          "Expected a single entry per aliasee in per-module index");
871   AS->setAliasee(AliaseeVI, AliaseeVI.getSummaryList()[0].get());
872   if (NonRenamableLocal)
873     CantBePromoted.insert(A.getGUID());
874   Index.addGlobalValueSummary(A, std::move(AS));
875 }
876 
877 // Set LiveRoot flag on entries matching the given value name.
setLiveRoot(ModuleSummaryIndex & Index,StringRef Name)878 static void setLiveRoot(ModuleSummaryIndex &Index, StringRef Name) {
879   if (ValueInfo VI = Index.getValueInfo(GlobalValue::getGUID(Name)))
880     for (const auto &Summary : VI.getSummaryList())
881       Summary->setLive(true);
882 }
883 
buildModuleSummaryIndex(const Module & M,std::function<BlockFrequencyInfo * (const Function & F)> GetBFICallback,ProfileSummaryInfo * PSI,std::function<const StackSafetyInfo * (const Function & F)> GetSSICallback)884 ModuleSummaryIndex llvm::buildModuleSummaryIndex(
885     const Module &M,
886     std::function<BlockFrequencyInfo *(const Function &F)> GetBFICallback,
887     ProfileSummaryInfo *PSI,
888     std::function<const StackSafetyInfo *(const Function &F)> GetSSICallback) {
889   assert(PSI);
890   bool EnableSplitLTOUnit = false;
891   bool UnifiedLTO = false;
892   if (auto *MD = mdconst::extract_or_null<ConstantInt>(
893           M.getModuleFlag("EnableSplitLTOUnit")))
894     EnableSplitLTOUnit = MD->getZExtValue();
895   if (auto *MD =
896           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("UnifiedLTO")))
897     UnifiedLTO = MD->getZExtValue();
898   ModuleSummaryIndex Index(/*HaveGVs=*/true, EnableSplitLTOUnit, UnifiedLTO);
899 
900   // Identify the local values in the llvm.used and llvm.compiler.used sets,
901   // which should not be exported as they would then require renaming and
902   // promotion, but we may have opaque uses e.g. in inline asm. We collect them
903   // here because we use this information to mark functions containing inline
904   // assembly calls as not importable.
905   SmallPtrSet<GlobalValue *, 4> LocalsUsed;
906   SmallVector<GlobalValue *, 4> Used;
907   // First collect those in the llvm.used set.
908   collectUsedGlobalVariables(M, Used, /*CompilerUsed=*/false);
909   // Next collect those in the llvm.compiler.used set.
910   collectUsedGlobalVariables(M, Used, /*CompilerUsed=*/true);
911   DenseSet<GlobalValue::GUID> CantBePromoted;
912   for (auto *V : Used) {
913     if (V->hasLocalLinkage()) {
914       LocalsUsed.insert(V);
915       CantBePromoted.insert(V->getGUID());
916     }
917   }
918 
919   bool HasLocalInlineAsmSymbol = false;
920   if (!M.getModuleInlineAsm().empty()) {
921     // Collect the local values defined by module level asm, and set up
922     // summaries for these symbols so that they can be marked as NoRename,
923     // to prevent export of any use of them in regular IR that would require
924     // renaming within the module level asm. Note we don't need to create a
925     // summary for weak or global defs, as they don't need to be flagged as
926     // NoRename, and defs in module level asm can't be imported anyway.
927     // Also, any values used but not defined within module level asm should
928     // be listed on the llvm.used or llvm.compiler.used global and marked as
929     // referenced from there.
930     ModuleSymbolTable::CollectAsmSymbols(
931         M, [&](StringRef Name, object::BasicSymbolRef::Flags Flags) {
932           // Symbols not marked as Weak or Global are local definitions.
933           if (Flags & (object::BasicSymbolRef::SF_Weak |
934                        object::BasicSymbolRef::SF_Global))
935             return;
936           HasLocalInlineAsmSymbol = true;
937           GlobalValue *GV = M.getNamedValue(Name);
938           if (!GV)
939             return;
940           assert(GV->isDeclaration() && "Def in module asm already has definition");
941           GlobalValueSummary::GVFlags GVFlags(
942               GlobalValue::InternalLinkage, GlobalValue::DefaultVisibility,
943               /* NotEligibleToImport = */ true,
944               /* Live = */ true,
945               /* Local */ GV->isDSOLocal(), GV->canBeOmittedFromSymbolTable(),
946               GlobalValueSummary::Definition);
947           CantBePromoted.insert(GV->getGUID());
948           // Create the appropriate summary type.
949           if (Function *F = dyn_cast<Function>(GV)) {
950             std::unique_ptr<FunctionSummary> Summary =
951                 std::make_unique<FunctionSummary>(
952                     GVFlags, /*InstCount=*/0,
953                     FunctionSummary::FFlags{
954                         F->hasFnAttribute(Attribute::ReadNone),
955                         F->hasFnAttribute(Attribute::ReadOnly),
956                         F->hasFnAttribute(Attribute::NoRecurse),
957                         F->returnDoesNotAlias(),
958                         /* NoInline = */ false,
959                         F->hasFnAttribute(Attribute::AlwaysInline),
960                         F->hasFnAttribute(Attribute::NoUnwind),
961                         /* MayThrow */ true,
962                         /* HasUnknownCall */ true,
963                         /* MustBeUnreachable */ false},
964                     /*EntryCount=*/0, ArrayRef<ValueInfo>{},
965                     ArrayRef<FunctionSummary::EdgeTy>{},
966                     ArrayRef<GlobalValue::GUID>{},
967                     ArrayRef<FunctionSummary::VFuncId>{},
968                     ArrayRef<FunctionSummary::VFuncId>{},
969                     ArrayRef<FunctionSummary::ConstVCall>{},
970                     ArrayRef<FunctionSummary::ConstVCall>{},
971                     ArrayRef<FunctionSummary::ParamAccess>{},
972                     ArrayRef<CallsiteInfo>{}, ArrayRef<AllocInfo>{});
973             Index.addGlobalValueSummary(*GV, std::move(Summary));
974           } else {
975             std::unique_ptr<GlobalVarSummary> Summary =
976                 std::make_unique<GlobalVarSummary>(
977                     GVFlags,
978                     GlobalVarSummary::GVarFlags(
979                         false, false, cast<GlobalVariable>(GV)->isConstant(),
980                         GlobalObject::VCallVisibilityPublic),
981                     ArrayRef<ValueInfo>{});
982             Index.addGlobalValueSummary(*GV, std::move(Summary));
983           }
984         });
985   }
986 
987   bool IsThinLTO = true;
988   if (auto *MD =
989           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
990     IsThinLTO = MD->getZExtValue();
991 
992   // Compute summaries for all functions defined in module, and save in the
993   // index.
994   for (const auto &F : M) {
995     if (F.isDeclaration())
996       continue;
997 
998     DominatorTree DT(const_cast<Function &>(F));
999     BlockFrequencyInfo *BFI = nullptr;
1000     std::unique_ptr<BlockFrequencyInfo> BFIPtr;
1001     if (GetBFICallback)
1002       BFI = GetBFICallback(F);
1003     else if (F.hasProfileData()) {
1004       LoopInfo LI{DT};
1005       BranchProbabilityInfo BPI{F, LI};
1006       BFIPtr = std::make_unique<BlockFrequencyInfo>(F, BPI, LI);
1007       BFI = BFIPtr.get();
1008     }
1009 
1010     computeFunctionSummary(Index, M, F, BFI, PSI, DT,
1011                            !LocalsUsed.empty() || HasLocalInlineAsmSymbol,
1012                            CantBePromoted, IsThinLTO, GetSSICallback);
1013   }
1014 
1015   // Compute summaries for all variables defined in module, and save in the
1016   // index.
1017   SmallVector<MDNode *, 2> Types;
1018   for (const GlobalVariable &G : M.globals()) {
1019     if (G.isDeclaration())
1020       continue;
1021     computeVariableSummary(Index, G, CantBePromoted, M, Types);
1022   }
1023 
1024   // Compute summaries for all aliases defined in module, and save in the
1025   // index.
1026   for (const GlobalAlias &A : M.aliases())
1027     computeAliasSummary(Index, A, CantBePromoted);
1028 
1029   // Iterate through ifuncs, set their resolvers all alive.
1030   for (const GlobalIFunc &I : M.ifuncs()) {
1031     I.applyAlongResolverPath([&Index](const GlobalValue &GV) {
1032       Index.getGlobalValueSummary(GV)->setLive(true);
1033     });
1034   }
1035 
1036   for (auto *V : LocalsUsed) {
1037     auto *Summary = Index.getGlobalValueSummary(*V);
1038     assert(Summary && "Missing summary for global value");
1039     Summary->setNotEligibleToImport();
1040   }
1041 
1042   // The linker doesn't know about these LLVM produced values, so we need
1043   // to flag them as live in the index to ensure index-based dead value
1044   // analysis treats them as live roots of the analysis.
1045   setLiveRoot(Index, "llvm.used");
1046   setLiveRoot(Index, "llvm.compiler.used");
1047   setLiveRoot(Index, "llvm.global_ctors");
1048   setLiveRoot(Index, "llvm.global_dtors");
1049   setLiveRoot(Index, "llvm.global.annotations");
1050 
1051   for (auto &GlobalList : Index) {
1052     // Ignore entries for references that are undefined in the current module.
1053     if (GlobalList.second.SummaryList.empty())
1054       continue;
1055 
1056     assert(GlobalList.second.SummaryList.size() == 1 &&
1057            "Expected module's index to have one summary per GUID");
1058     auto &Summary = GlobalList.second.SummaryList[0];
1059     if (!IsThinLTO) {
1060       Summary->setNotEligibleToImport();
1061       continue;
1062     }
1063 
1064     bool AllRefsCanBeExternallyReferenced =
1065         llvm::all_of(Summary->refs(), [&](const ValueInfo &VI) {
1066           return !CantBePromoted.count(VI.getGUID());
1067         });
1068     if (!AllRefsCanBeExternallyReferenced) {
1069       Summary->setNotEligibleToImport();
1070       continue;
1071     }
1072 
1073     if (auto *FuncSummary = dyn_cast<FunctionSummary>(Summary.get())) {
1074       bool AllCallsCanBeExternallyReferenced = llvm::all_of(
1075           FuncSummary->calls(), [&](const FunctionSummary::EdgeTy &Edge) {
1076             return !CantBePromoted.count(Edge.first.getGUID());
1077           });
1078       if (!AllCallsCanBeExternallyReferenced)
1079         Summary->setNotEligibleToImport();
1080     }
1081   }
1082 
1083   if (!ModuleSummaryDotFile.empty()) {
1084     std::error_code EC;
1085     raw_fd_ostream OSDot(ModuleSummaryDotFile, EC, sys::fs::OpenFlags::OF_Text);
1086     if (EC)
1087       report_fatal_error(Twine("Failed to open dot file ") +
1088                          ModuleSummaryDotFile + ": " + EC.message() + "\n");
1089     Index.exportToDot(OSDot, {});
1090   }
1091 
1092   return Index;
1093 }
1094 
1095 AnalysisKey ModuleSummaryIndexAnalysis::Key;
1096 
1097 ModuleSummaryIndex
run(Module & M,ModuleAnalysisManager & AM)1098 ModuleSummaryIndexAnalysis::run(Module &M, ModuleAnalysisManager &AM) {
1099   ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
1100   auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
1101   bool NeedSSI = needsParamAccessSummary(M);
1102   return buildModuleSummaryIndex(
1103       M,
1104       [&FAM](const Function &F) {
1105         return &FAM.getResult<BlockFrequencyAnalysis>(
1106             *const_cast<Function *>(&F));
1107       },
1108       &PSI,
1109       [&FAM, NeedSSI](const Function &F) -> const StackSafetyInfo * {
1110         return NeedSSI ? &FAM.getResult<StackSafetyAnalysis>(
1111                              const_cast<Function &>(F))
1112                        : nullptr;
1113       });
1114 }
1115 
1116 char ModuleSummaryIndexWrapperPass::ID = 0;
1117 
1118 INITIALIZE_PASS_BEGIN(ModuleSummaryIndexWrapperPass, "module-summary-analysis",
1119                       "Module Summary Analysis", false, true)
INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)1120 INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
1121 INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
1122 INITIALIZE_PASS_DEPENDENCY(StackSafetyInfoWrapperPass)
1123 INITIALIZE_PASS_END(ModuleSummaryIndexWrapperPass, "module-summary-analysis",
1124                     "Module Summary Analysis", false, true)
1125 
1126 ModulePass *llvm::createModuleSummaryIndexWrapperPass() {
1127   return new ModuleSummaryIndexWrapperPass();
1128 }
1129 
ModuleSummaryIndexWrapperPass()1130 ModuleSummaryIndexWrapperPass::ModuleSummaryIndexWrapperPass()
1131     : ModulePass(ID) {
1132   initializeModuleSummaryIndexWrapperPassPass(*PassRegistry::getPassRegistry());
1133 }
1134 
runOnModule(Module & M)1135 bool ModuleSummaryIndexWrapperPass::runOnModule(Module &M) {
1136   auto *PSI = &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
1137   bool NeedSSI = needsParamAccessSummary(M);
1138   Index.emplace(buildModuleSummaryIndex(
1139       M,
1140       [this](const Function &F) {
1141         return &(this->getAnalysis<BlockFrequencyInfoWrapperPass>(
1142                          *const_cast<Function *>(&F))
1143                      .getBFI());
1144       },
1145       PSI,
1146       [&](const Function &F) -> const StackSafetyInfo * {
1147         return NeedSSI ? &getAnalysis<StackSafetyInfoWrapperPass>(
1148                               const_cast<Function &>(F))
1149                               .getResult()
1150                        : nullptr;
1151       }));
1152   return false;
1153 }
1154 
doFinalization(Module & M)1155 bool ModuleSummaryIndexWrapperPass::doFinalization(Module &M) {
1156   Index.reset();
1157   return false;
1158 }
1159 
getAnalysisUsage(AnalysisUsage & AU) const1160 void ModuleSummaryIndexWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
1161   AU.setPreservesAll();
1162   AU.addRequired<BlockFrequencyInfoWrapperPass>();
1163   AU.addRequired<ProfileSummaryInfoWrapperPass>();
1164   AU.addRequired<StackSafetyInfoWrapperPass>();
1165 }
1166 
1167 char ImmutableModuleSummaryIndexWrapperPass::ID = 0;
1168 
ImmutableModuleSummaryIndexWrapperPass(const ModuleSummaryIndex * Index)1169 ImmutableModuleSummaryIndexWrapperPass::ImmutableModuleSummaryIndexWrapperPass(
1170     const ModuleSummaryIndex *Index)
1171     : ImmutablePass(ID), Index(Index) {
1172   initializeImmutableModuleSummaryIndexWrapperPassPass(
1173       *PassRegistry::getPassRegistry());
1174 }
1175 
getAnalysisUsage(AnalysisUsage & AU) const1176 void ImmutableModuleSummaryIndexWrapperPass::getAnalysisUsage(
1177     AnalysisUsage &AU) const {
1178   AU.setPreservesAll();
1179 }
1180 
createImmutableModuleSummaryIndexWrapperPass(const ModuleSummaryIndex * Index)1181 ImmutablePass *llvm::createImmutableModuleSummaryIndexWrapperPass(
1182     const ModuleSummaryIndex *Index) {
1183   return new ImmutableModuleSummaryIndexWrapperPass(Index);
1184 }
1185 
1186 INITIALIZE_PASS(ImmutableModuleSummaryIndexWrapperPass, "module-summary-info",
1187                 "Module summary info", false, true)
1188 
mayHaveMemprofSummary(const CallBase * CB)1189 bool llvm::mayHaveMemprofSummary(const CallBase *CB) {
1190   if (!CB)
1191     return false;
1192   if (CB->isDebugOrPseudoInst())
1193     return false;
1194   auto *CI = dyn_cast<CallInst>(CB);
1195   auto *CalledValue = CB->getCalledOperand();
1196   auto *CalledFunction = CB->getCalledFunction();
1197   if (CalledValue && !CalledFunction) {
1198     CalledValue = CalledValue->stripPointerCasts();
1199     // Stripping pointer casts can reveal a called function.
1200     CalledFunction = dyn_cast<Function>(CalledValue);
1201   }
1202   // Check if this is an alias to a function. If so, get the
1203   // called aliasee for the checks below.
1204   if (auto *GA = dyn_cast<GlobalAlias>(CalledValue)) {
1205     assert(!CalledFunction &&
1206            "Expected null called function in callsite for alias");
1207     CalledFunction = dyn_cast<Function>(GA->getAliaseeObject());
1208   }
1209   // Check if this is a direct call to a known function or a known
1210   // intrinsic, or an indirect call with profile data.
1211   if (CalledFunction) {
1212     if (CI && CalledFunction->isIntrinsic())
1213       return false;
1214   } else {
1215     // TODO: For now skip indirect calls. See comments in
1216     // computeFunctionSummary for what is needed to handle this.
1217     return false;
1218   }
1219   return true;
1220 }
1221