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1 //===- ModuleSummaryAnalysis.cpp - Module summary index builder -----------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This pass builds a ModuleSummaryIndex object for the module, to be written
11 // to bitcode or LLVM assembly.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/Analysis/ModuleSummaryAnalysis.h"
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/ADT/DenseSet.h"
18 #include "llvm/ADT/MapVector.h"
19 #include "llvm/ADT/STLExtras.h"
20 #include "llvm/ADT/SetVector.h"
21 #include "llvm/ADT/SmallPtrSet.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/StringRef.h"
24 #include "llvm/Analysis/BlockFrequencyInfo.h"
25 #include "llvm/Analysis/BranchProbabilityInfo.h"
26 #include "llvm/Analysis/IndirectCallPromotionAnalysis.h"
27 #include "llvm/Analysis/LoopInfo.h"
28 #include "llvm/Analysis/ProfileSummaryInfo.h"
29 #include "llvm/Analysis/TypeMetadataUtils.h"
30 #include "llvm/IR/Attributes.h"
31 #include "llvm/IR/BasicBlock.h"
32 #include "llvm/IR/CallSite.h"
33 #include "llvm/IR/Constant.h"
34 #include "llvm/IR/Constants.h"
35 #include "llvm/IR/Dominators.h"
36 #include "llvm/IR/Function.h"
37 #include "llvm/IR/GlobalAlias.h"
38 #include "llvm/IR/GlobalValue.h"
39 #include "llvm/IR/GlobalVariable.h"
40 #include "llvm/IR/Instructions.h"
41 #include "llvm/IR/IntrinsicInst.h"
42 #include "llvm/IR/Intrinsics.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/Object/ModuleSymbolTable.h"
49 #include "llvm/Object/SymbolicFile.h"
50 #include "llvm/Pass.h"
51 #include "llvm/Support/Casting.h"
52 #include "llvm/Support/CommandLine.h"
53 #include <algorithm>
54 #include <cassert>
55 #include <cstdint>
56 #include <vector>
57 
58 using namespace llvm;
59 
60 #define DEBUG_TYPE "module-summary-analysis"
61 
62 // Option to force edges cold which will block importing when the
63 // -import-cold-multiplier is set to 0. Useful for debugging.
64 FunctionSummary::ForceSummaryHotnessType ForceSummaryEdgesCold =
65     FunctionSummary::FSHT_None;
66 cl::opt<FunctionSummary::ForceSummaryHotnessType, true> FSEC(
67     "force-summary-edges-cold", cl::Hidden, cl::location(ForceSummaryEdgesCold),
68     cl::desc("Force all edges in the function summary to cold"),
69     cl::values(clEnumValN(FunctionSummary::FSHT_None, "none", "None."),
70                clEnumValN(FunctionSummary::FSHT_AllNonCritical,
71                           "all-non-critical", "All non-critical edges."),
72                clEnumValN(FunctionSummary::FSHT_All, "all", "All edges.")));
73 
74 // Walk through the operands of a given User via worklist iteration and populate
75 // the set of GlobalValue references encountered. Invoked either on an
76 // Instruction or a GlobalVariable (which walks its initializer).
77 // Return true if any of the operands contains blockaddress. This is important
78 // to know when computing summary for global var, because if global variable
79 // references basic block address we can't import it separately from function
80 // containing that basic block. For simplicity we currently don't import such
81 // global vars at all. When importing function we aren't interested if any
82 // instruction in it takes an address of any basic block, because instruction
83 // can only take an address of basic block located in the same function.
findRefEdges(ModuleSummaryIndex & Index,const User * CurUser,SetVector<ValueInfo> & RefEdges,SmallPtrSet<const User *,8> & Visited)84 static bool findRefEdges(ModuleSummaryIndex &Index, const User *CurUser,
85                          SetVector<ValueInfo> &RefEdges,
86                          SmallPtrSet<const User *, 8> &Visited) {
87   bool HasBlockAddress = false;
88   SmallVector<const User *, 32> Worklist;
89   Worklist.push_back(CurUser);
90 
91   while (!Worklist.empty()) {
92     const User *U = Worklist.pop_back_val();
93 
94     if (!Visited.insert(U).second)
95       continue;
96 
97     ImmutableCallSite CS(U);
98 
99     for (const auto &OI : U->operands()) {
100       const User *Operand = dyn_cast<User>(OI);
101       if (!Operand)
102         continue;
103       if (isa<BlockAddress>(Operand)) {
104         HasBlockAddress = true;
105         continue;
106       }
107       if (auto *GV = dyn_cast<GlobalValue>(Operand)) {
108         // We have a reference to a global value. This should be added to
109         // the reference set unless it is a callee. Callees are handled
110         // specially by WriteFunction and are added to a separate list.
111         if (!(CS && CS.isCallee(&OI)))
112           RefEdges.insert(Index.getOrInsertValueInfo(GV));
113         continue;
114       }
115       Worklist.push_back(Operand);
116     }
117   }
118   return HasBlockAddress;
119 }
120 
getHotness(uint64_t ProfileCount,ProfileSummaryInfo * PSI)121 static CalleeInfo::HotnessType getHotness(uint64_t ProfileCount,
122                                           ProfileSummaryInfo *PSI) {
123   if (!PSI)
124     return CalleeInfo::HotnessType::Unknown;
125   if (PSI->isHotCount(ProfileCount))
126     return CalleeInfo::HotnessType::Hot;
127   if (PSI->isColdCount(ProfileCount))
128     return CalleeInfo::HotnessType::Cold;
129   return CalleeInfo::HotnessType::None;
130 }
131 
isNonRenamableLocal(const GlobalValue & GV)132 static bool isNonRenamableLocal(const GlobalValue &GV) {
133   return GV.hasSection() && GV.hasLocalLinkage();
134 }
135 
136 /// Determine whether this call has all constant integer arguments (excluding
137 /// "this") and summarize it to VCalls or ConstVCalls as appropriate.
addVCallToSet(DevirtCallSite Call,GlobalValue::GUID Guid,SetVector<FunctionSummary::VFuncId> & VCalls,SetVector<FunctionSummary::ConstVCall> & ConstVCalls)138 static void addVCallToSet(DevirtCallSite Call, GlobalValue::GUID Guid,
139                           SetVector<FunctionSummary::VFuncId> &VCalls,
140                           SetVector<FunctionSummary::ConstVCall> &ConstVCalls) {
141   std::vector<uint64_t> Args;
142   // Start from the second argument to skip the "this" pointer.
143   for (auto &Arg : make_range(Call.CS.arg_begin() + 1, Call.CS.arg_end())) {
144     auto *CI = dyn_cast<ConstantInt>(Arg);
145     if (!CI || CI->getBitWidth() > 64) {
146       VCalls.insert({Guid, Call.Offset});
147       return;
148     }
149     Args.push_back(CI->getZExtValue());
150   }
151   ConstVCalls.insert({{Guid, Call.Offset}, std::move(Args)});
152 }
153 
154 /// If this intrinsic call requires that we add information to the function
155 /// summary, do so via the non-constant reference arguments.
addIntrinsicToSummary(const CallInst * CI,SetVector<GlobalValue::GUID> & TypeTests,SetVector<FunctionSummary::VFuncId> & TypeTestAssumeVCalls,SetVector<FunctionSummary::VFuncId> & TypeCheckedLoadVCalls,SetVector<FunctionSummary::ConstVCall> & TypeTestAssumeConstVCalls,SetVector<FunctionSummary::ConstVCall> & TypeCheckedLoadConstVCalls)156 static void addIntrinsicToSummary(
157     const CallInst *CI, SetVector<GlobalValue::GUID> &TypeTests,
158     SetVector<FunctionSummary::VFuncId> &TypeTestAssumeVCalls,
159     SetVector<FunctionSummary::VFuncId> &TypeCheckedLoadVCalls,
160     SetVector<FunctionSummary::ConstVCall> &TypeTestAssumeConstVCalls,
161     SetVector<FunctionSummary::ConstVCall> &TypeCheckedLoadConstVCalls) {
162   switch (CI->getCalledFunction()->getIntrinsicID()) {
163   case Intrinsic::type_test: {
164     auto *TypeMDVal = cast<MetadataAsValue>(CI->getArgOperand(1));
165     auto *TypeId = dyn_cast<MDString>(TypeMDVal->getMetadata());
166     if (!TypeId)
167       break;
168     GlobalValue::GUID Guid = GlobalValue::getGUID(TypeId->getString());
169 
170     // Produce a summary from type.test intrinsics. We only summarize type.test
171     // intrinsics that are used other than by an llvm.assume intrinsic.
172     // Intrinsics that are assumed are relevant only to the devirtualization
173     // pass, not the type test lowering pass.
174     bool HasNonAssumeUses = llvm::any_of(CI->uses(), [](const Use &CIU) {
175       auto *AssumeCI = dyn_cast<CallInst>(CIU.getUser());
176       if (!AssumeCI)
177         return true;
178       Function *F = AssumeCI->getCalledFunction();
179       return !F || F->getIntrinsicID() != Intrinsic::assume;
180     });
181     if (HasNonAssumeUses)
182       TypeTests.insert(Guid);
183 
184     SmallVector<DevirtCallSite, 4> DevirtCalls;
185     SmallVector<CallInst *, 4> Assumes;
186     findDevirtualizableCallsForTypeTest(DevirtCalls, Assumes, CI);
187     for (auto &Call : DevirtCalls)
188       addVCallToSet(Call, Guid, TypeTestAssumeVCalls,
189                     TypeTestAssumeConstVCalls);
190 
191     break;
192   }
193 
194   case Intrinsic::type_checked_load: {
195     auto *TypeMDVal = cast<MetadataAsValue>(CI->getArgOperand(2));
196     auto *TypeId = dyn_cast<MDString>(TypeMDVal->getMetadata());
197     if (!TypeId)
198       break;
199     GlobalValue::GUID Guid = GlobalValue::getGUID(TypeId->getString());
200 
201     SmallVector<DevirtCallSite, 4> DevirtCalls;
202     SmallVector<Instruction *, 4> LoadedPtrs;
203     SmallVector<Instruction *, 4> Preds;
204     bool HasNonCallUses = false;
205     findDevirtualizableCallsForTypeCheckedLoad(DevirtCalls, LoadedPtrs, Preds,
206                                                HasNonCallUses, CI);
207     // Any non-call uses of the result of llvm.type.checked.load will
208     // prevent us from optimizing away the llvm.type.test.
209     if (HasNonCallUses)
210       TypeTests.insert(Guid);
211     for (auto &Call : DevirtCalls)
212       addVCallToSet(Call, Guid, TypeCheckedLoadVCalls,
213                     TypeCheckedLoadConstVCalls);
214 
215     break;
216   }
217   default:
218     break;
219   }
220 }
221 
222 static void
computeFunctionSummary(ModuleSummaryIndex & Index,const Module & M,const Function & F,BlockFrequencyInfo * BFI,ProfileSummaryInfo * PSI,bool HasLocalsInUsedOrAsm,DenseSet<GlobalValue::GUID> & CantBePromoted)223 computeFunctionSummary(ModuleSummaryIndex &Index, const Module &M,
224                        const Function &F, BlockFrequencyInfo *BFI,
225                        ProfileSummaryInfo *PSI, bool HasLocalsInUsedOrAsm,
226                        DenseSet<GlobalValue::GUID> &CantBePromoted) {
227   // Summary not currently supported for anonymous functions, they should
228   // have been named.
229   assert(F.hasName());
230 
231   unsigned NumInsts = 0;
232   // Map from callee ValueId to profile count. Used to accumulate profile
233   // counts for all static calls to a given callee.
234   MapVector<ValueInfo, CalleeInfo> CallGraphEdges;
235   SetVector<ValueInfo> RefEdges;
236   SetVector<GlobalValue::GUID> TypeTests;
237   SetVector<FunctionSummary::VFuncId> TypeTestAssumeVCalls,
238       TypeCheckedLoadVCalls;
239   SetVector<FunctionSummary::ConstVCall> TypeTestAssumeConstVCalls,
240       TypeCheckedLoadConstVCalls;
241   ICallPromotionAnalysis ICallAnalysis;
242   SmallPtrSet<const User *, 8> Visited;
243 
244   // Add personality function, prefix data and prologue data to function's ref
245   // list.
246   findRefEdges(Index, &F, RefEdges, Visited);
247 
248   bool HasInlineAsmMaybeReferencingInternal = false;
249   for (const BasicBlock &BB : F)
250     for (const Instruction &I : BB) {
251       if (isa<DbgInfoIntrinsic>(I))
252         continue;
253       ++NumInsts;
254       findRefEdges(Index, &I, RefEdges, Visited);
255       auto CS = ImmutableCallSite(&I);
256       if (!CS)
257         continue;
258 
259       const auto *CI = dyn_cast<CallInst>(&I);
260       // Since we don't know exactly which local values are referenced in inline
261       // assembly, conservatively mark the function as possibly referencing
262       // a local value from inline assembly to ensure we don't export a
263       // reference (which would require renaming and promotion of the
264       // referenced value).
265       if (HasLocalsInUsedOrAsm && CI && CI->isInlineAsm())
266         HasInlineAsmMaybeReferencingInternal = true;
267 
268       auto *CalledValue = CS.getCalledValue();
269       auto *CalledFunction = CS.getCalledFunction();
270       if (CalledValue && !CalledFunction) {
271         CalledValue = CalledValue->stripPointerCastsNoFollowAliases();
272         // Stripping pointer casts can reveal a called function.
273         CalledFunction = dyn_cast<Function>(CalledValue);
274       }
275       // Check if this is an alias to a function. If so, get the
276       // called aliasee for the checks below.
277       if (auto *GA = dyn_cast<GlobalAlias>(CalledValue)) {
278         assert(!CalledFunction && "Expected null called function in callsite for alias");
279         CalledFunction = dyn_cast<Function>(GA->getBaseObject());
280       }
281       // Check if this is a direct call to a known function or a known
282       // intrinsic, or an indirect call with profile data.
283       if (CalledFunction) {
284         if (CI && CalledFunction->isIntrinsic()) {
285           addIntrinsicToSummary(
286               CI, TypeTests, TypeTestAssumeVCalls, TypeCheckedLoadVCalls,
287               TypeTestAssumeConstVCalls, TypeCheckedLoadConstVCalls);
288           continue;
289         }
290         // We should have named any anonymous globals
291         assert(CalledFunction->hasName());
292         auto ScaledCount = PSI->getProfileCount(&I, BFI);
293         auto Hotness = ScaledCount ? getHotness(ScaledCount.getValue(), PSI)
294                                    : CalleeInfo::HotnessType::Unknown;
295         if (ForceSummaryEdgesCold != FunctionSummary::FSHT_None)
296           Hotness = CalleeInfo::HotnessType::Cold;
297 
298         // Use the original CalledValue, in case it was an alias. We want
299         // to record the call edge to the alias in that case. Eventually
300         // an alias summary will be created to associate the alias and
301         // aliasee.
302         auto &ValueInfo = CallGraphEdges[Index.getOrInsertValueInfo(
303             cast<GlobalValue>(CalledValue))];
304         ValueInfo.updateHotness(Hotness);
305         // Add the relative block frequency to CalleeInfo if there is no profile
306         // information.
307         if (BFI != nullptr && Hotness == CalleeInfo::HotnessType::Unknown) {
308           uint64_t BBFreq = BFI->getBlockFreq(&BB).getFrequency();
309           uint64_t EntryFreq = BFI->getEntryFreq();
310           ValueInfo.updateRelBlockFreq(BBFreq, EntryFreq);
311         }
312       } else {
313         // Skip inline assembly calls.
314         if (CI && CI->isInlineAsm())
315           continue;
316         // Skip direct calls.
317         if (!CalledValue || isa<Constant>(CalledValue))
318           continue;
319 
320         // Check if the instruction has a callees metadata. If so, add callees
321         // to CallGraphEdges to reflect the references from the metadata, and
322         // to enable importing for subsequent indirect call promotion and
323         // inlining.
324         if (auto *MD = I.getMetadata(LLVMContext::MD_callees)) {
325           for (auto &Op : MD->operands()) {
326             Function *Callee = mdconst::extract_or_null<Function>(Op);
327             if (Callee)
328               CallGraphEdges[Index.getOrInsertValueInfo(Callee)];
329           }
330         }
331 
332         uint32_t NumVals, NumCandidates;
333         uint64_t TotalCount;
334         auto CandidateProfileData =
335             ICallAnalysis.getPromotionCandidatesForInstruction(
336                 &I, NumVals, TotalCount, NumCandidates);
337         for (auto &Candidate : CandidateProfileData)
338           CallGraphEdges[Index.getOrInsertValueInfo(Candidate.Value)]
339               .updateHotness(getHotness(Candidate.Count, PSI));
340       }
341     }
342 
343   // Explicit add hot edges to enforce importing for designated GUIDs for
344   // sample PGO, to enable the same inlines as the profiled optimized binary.
345   for (auto &I : F.getImportGUIDs())
346     CallGraphEdges[Index.getOrInsertValueInfo(I)].updateHotness(
347         ForceSummaryEdgesCold == FunctionSummary::FSHT_All
348             ? CalleeInfo::HotnessType::Cold
349             : CalleeInfo::HotnessType::Critical);
350 
351   bool NonRenamableLocal = isNonRenamableLocal(F);
352   bool NotEligibleForImport =
353       NonRenamableLocal || HasInlineAsmMaybeReferencingInternal ||
354       // Inliner doesn't handle variadic functions.
355       // FIXME: refactor this to use the same code that inliner is using.
356       F.isVarArg() ||
357       // Don't try to import functions with noinline attribute.
358       F.getAttributes().hasFnAttribute(Attribute::NoInline);
359   GlobalValueSummary::GVFlags Flags(F.getLinkage(), NotEligibleForImport,
360                                     /* Live = */ false, F.isDSOLocal());
361   FunctionSummary::FFlags FunFlags{
362       F.hasFnAttribute(Attribute::ReadNone),
363       F.hasFnAttribute(Attribute::ReadOnly),
364       F.hasFnAttribute(Attribute::NoRecurse),
365       F.returnDoesNotAlias(),
366   };
367   auto FuncSummary = llvm::make_unique<FunctionSummary>(
368       Flags, NumInsts, FunFlags, RefEdges.takeVector(),
369       CallGraphEdges.takeVector(), TypeTests.takeVector(),
370       TypeTestAssumeVCalls.takeVector(), TypeCheckedLoadVCalls.takeVector(),
371       TypeTestAssumeConstVCalls.takeVector(),
372       TypeCheckedLoadConstVCalls.takeVector());
373   if (NonRenamableLocal)
374     CantBePromoted.insert(F.getGUID());
375   Index.addGlobalValueSummary(F, std::move(FuncSummary));
376 }
377 
378 static void
computeVariableSummary(ModuleSummaryIndex & Index,const GlobalVariable & V,DenseSet<GlobalValue::GUID> & CantBePromoted)379 computeVariableSummary(ModuleSummaryIndex &Index, const GlobalVariable &V,
380                        DenseSet<GlobalValue::GUID> &CantBePromoted) {
381   SetVector<ValueInfo> RefEdges;
382   SmallPtrSet<const User *, 8> Visited;
383   bool HasBlockAddress = findRefEdges(Index, &V, RefEdges, Visited);
384   bool NonRenamableLocal = isNonRenamableLocal(V);
385   GlobalValueSummary::GVFlags Flags(V.getLinkage(), NonRenamableLocal,
386                                     /* Live = */ false, V.isDSOLocal());
387   auto GVarSummary =
388       llvm::make_unique<GlobalVarSummary>(Flags, RefEdges.takeVector());
389   if (NonRenamableLocal)
390     CantBePromoted.insert(V.getGUID());
391   if (HasBlockAddress)
392     GVarSummary->setNotEligibleToImport();
393   Index.addGlobalValueSummary(V, std::move(GVarSummary));
394 }
395 
396 static void
computeAliasSummary(ModuleSummaryIndex & Index,const GlobalAlias & A,DenseSet<GlobalValue::GUID> & CantBePromoted)397 computeAliasSummary(ModuleSummaryIndex &Index, const GlobalAlias &A,
398                     DenseSet<GlobalValue::GUID> &CantBePromoted) {
399   bool NonRenamableLocal = isNonRenamableLocal(A);
400   GlobalValueSummary::GVFlags Flags(A.getLinkage(), NonRenamableLocal,
401                                     /* Live = */ false, A.isDSOLocal());
402   auto AS = llvm::make_unique<AliasSummary>(Flags);
403   auto *Aliasee = A.getBaseObject();
404   auto *AliaseeSummary = Index.getGlobalValueSummary(*Aliasee);
405   assert(AliaseeSummary && "Alias expects aliasee summary to be parsed");
406   AS->setAliasee(AliaseeSummary);
407   if (NonRenamableLocal)
408     CantBePromoted.insert(A.getGUID());
409   Index.addGlobalValueSummary(A, std::move(AS));
410 }
411 
412 // Set LiveRoot flag on entries matching the given value name.
setLiveRoot(ModuleSummaryIndex & Index,StringRef Name)413 static void setLiveRoot(ModuleSummaryIndex &Index, StringRef Name) {
414   if (ValueInfo VI = Index.getValueInfo(GlobalValue::getGUID(Name)))
415     for (auto &Summary : VI.getSummaryList())
416       Summary->setLive(true);
417 }
418 
buildModuleSummaryIndex(const Module & M,std::function<BlockFrequencyInfo * (const Function & F)> GetBFICallback,ProfileSummaryInfo * PSI)419 ModuleSummaryIndex llvm::buildModuleSummaryIndex(
420     const Module &M,
421     std::function<BlockFrequencyInfo *(const Function &F)> GetBFICallback,
422     ProfileSummaryInfo *PSI) {
423   assert(PSI);
424   ModuleSummaryIndex Index(/*HaveGVs=*/true);
425 
426   // Identify the local values in the llvm.used and llvm.compiler.used sets,
427   // which should not be exported as they would then require renaming and
428   // promotion, but we may have opaque uses e.g. in inline asm. We collect them
429   // here because we use this information to mark functions containing inline
430   // assembly calls as not importable.
431   SmallPtrSet<GlobalValue *, 8> LocalsUsed;
432   SmallPtrSet<GlobalValue *, 8> Used;
433   // First collect those in the llvm.used set.
434   collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);
435   // Next collect those in the llvm.compiler.used set.
436   collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ true);
437   DenseSet<GlobalValue::GUID> CantBePromoted;
438   for (auto *V : Used) {
439     if (V->hasLocalLinkage()) {
440       LocalsUsed.insert(V);
441       CantBePromoted.insert(V->getGUID());
442     }
443   }
444 
445   bool HasLocalInlineAsmSymbol = false;
446   if (!M.getModuleInlineAsm().empty()) {
447     // Collect the local values defined by module level asm, and set up
448     // summaries for these symbols so that they can be marked as NoRename,
449     // to prevent export of any use of them in regular IR that would require
450     // renaming within the module level asm. Note we don't need to create a
451     // summary for weak or global defs, as they don't need to be flagged as
452     // NoRename, and defs in module level asm can't be imported anyway.
453     // Also, any values used but not defined within module level asm should
454     // be listed on the llvm.used or llvm.compiler.used global and marked as
455     // referenced from there.
456     ModuleSymbolTable::CollectAsmSymbols(
457         M, [&](StringRef Name, object::BasicSymbolRef::Flags Flags) {
458           // Symbols not marked as Weak or Global are local definitions.
459           if (Flags & (object::BasicSymbolRef::SF_Weak |
460                        object::BasicSymbolRef::SF_Global))
461             return;
462           HasLocalInlineAsmSymbol = true;
463           GlobalValue *GV = M.getNamedValue(Name);
464           if (!GV)
465             return;
466           assert(GV->isDeclaration() && "Def in module asm already has definition");
467           GlobalValueSummary::GVFlags GVFlags(GlobalValue::InternalLinkage,
468                                               /* NotEligibleToImport = */ true,
469                                               /* Live = */ true,
470                                               /* Local */ GV->isDSOLocal());
471           CantBePromoted.insert(GV->getGUID());
472           // Create the appropriate summary type.
473           if (Function *F = dyn_cast<Function>(GV)) {
474             std::unique_ptr<FunctionSummary> Summary =
475                 llvm::make_unique<FunctionSummary>(
476                     GVFlags, 0,
477                     FunctionSummary::FFlags{
478                         F->hasFnAttribute(Attribute::ReadNone),
479                         F->hasFnAttribute(Attribute::ReadOnly),
480                         F->hasFnAttribute(Attribute::NoRecurse),
481                         F->returnDoesNotAlias()},
482                     ArrayRef<ValueInfo>{}, ArrayRef<FunctionSummary::EdgeTy>{},
483                     ArrayRef<GlobalValue::GUID>{},
484                     ArrayRef<FunctionSummary::VFuncId>{},
485                     ArrayRef<FunctionSummary::VFuncId>{},
486                     ArrayRef<FunctionSummary::ConstVCall>{},
487                     ArrayRef<FunctionSummary::ConstVCall>{});
488             Index.addGlobalValueSummary(*GV, std::move(Summary));
489           } else {
490             std::unique_ptr<GlobalVarSummary> Summary =
491                 llvm::make_unique<GlobalVarSummary>(GVFlags,
492                                                     ArrayRef<ValueInfo>{});
493             Index.addGlobalValueSummary(*GV, std::move(Summary));
494           }
495         });
496   }
497 
498   // Compute summaries for all functions defined in module, and save in the
499   // index.
500   for (auto &F : M) {
501     if (F.isDeclaration())
502       continue;
503 
504     BlockFrequencyInfo *BFI = nullptr;
505     std::unique_ptr<BlockFrequencyInfo> BFIPtr;
506     if (GetBFICallback)
507       BFI = GetBFICallback(F);
508     else if (F.hasProfileData()) {
509       LoopInfo LI{DominatorTree(const_cast<Function &>(F))};
510       BranchProbabilityInfo BPI{F, LI};
511       BFIPtr = llvm::make_unique<BlockFrequencyInfo>(F, BPI, LI);
512       BFI = BFIPtr.get();
513     }
514 
515     computeFunctionSummary(Index, M, F, BFI, PSI,
516                            !LocalsUsed.empty() || HasLocalInlineAsmSymbol,
517                            CantBePromoted);
518   }
519 
520   // Compute summaries for all variables defined in module, and save in the
521   // index.
522   for (const GlobalVariable &G : M.globals()) {
523     if (G.isDeclaration())
524       continue;
525     computeVariableSummary(Index, G, CantBePromoted);
526   }
527 
528   // Compute summaries for all aliases defined in module, and save in the
529   // index.
530   for (const GlobalAlias &A : M.aliases())
531     computeAliasSummary(Index, A, CantBePromoted);
532 
533   for (auto *V : LocalsUsed) {
534     auto *Summary = Index.getGlobalValueSummary(*V);
535     assert(Summary && "Missing summary for global value");
536     Summary->setNotEligibleToImport();
537   }
538 
539   // The linker doesn't know about these LLVM produced values, so we need
540   // to flag them as live in the index to ensure index-based dead value
541   // analysis treats them as live roots of the analysis.
542   setLiveRoot(Index, "llvm.used");
543   setLiveRoot(Index, "llvm.compiler.used");
544   setLiveRoot(Index, "llvm.global_ctors");
545   setLiveRoot(Index, "llvm.global_dtors");
546   setLiveRoot(Index, "llvm.global.annotations");
547 
548   bool IsThinLTO = true;
549   if (auto *MD =
550           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
551     IsThinLTO = MD->getZExtValue();
552 
553   for (auto &GlobalList : Index) {
554     // Ignore entries for references that are undefined in the current module.
555     if (GlobalList.second.SummaryList.empty())
556       continue;
557 
558     assert(GlobalList.second.SummaryList.size() == 1 &&
559            "Expected module's index to have one summary per GUID");
560     auto &Summary = GlobalList.second.SummaryList[0];
561     if (!IsThinLTO) {
562       Summary->setNotEligibleToImport();
563       continue;
564     }
565 
566     bool AllRefsCanBeExternallyReferenced =
567         llvm::all_of(Summary->refs(), [&](const ValueInfo &VI) {
568           return !CantBePromoted.count(VI.getGUID());
569         });
570     if (!AllRefsCanBeExternallyReferenced) {
571       Summary->setNotEligibleToImport();
572       continue;
573     }
574 
575     if (auto *FuncSummary = dyn_cast<FunctionSummary>(Summary.get())) {
576       bool AllCallsCanBeExternallyReferenced = llvm::all_of(
577           FuncSummary->calls(), [&](const FunctionSummary::EdgeTy &Edge) {
578             return !CantBePromoted.count(Edge.first.getGUID());
579           });
580       if (!AllCallsCanBeExternallyReferenced)
581         Summary->setNotEligibleToImport();
582     }
583   }
584 
585   return Index;
586 }
587 
588 AnalysisKey ModuleSummaryIndexAnalysis::Key;
589 
590 ModuleSummaryIndex
run(Module & M,ModuleAnalysisManager & AM)591 ModuleSummaryIndexAnalysis::run(Module &M, ModuleAnalysisManager &AM) {
592   ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
593   auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
594   return buildModuleSummaryIndex(
595       M,
596       [&FAM](const Function &F) {
597         return &FAM.getResult<BlockFrequencyAnalysis>(
598             *const_cast<Function *>(&F));
599       },
600       &PSI);
601 }
602 
603 char ModuleSummaryIndexWrapperPass::ID = 0;
604 
605 INITIALIZE_PASS_BEGIN(ModuleSummaryIndexWrapperPass, "module-summary-analysis",
606                       "Module Summary Analysis", false, true)
INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)607 INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
608 INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
609 INITIALIZE_PASS_END(ModuleSummaryIndexWrapperPass, "module-summary-analysis",
610                     "Module Summary Analysis", false, true)
611 
612 ModulePass *llvm::createModuleSummaryIndexWrapperPass() {
613   return new ModuleSummaryIndexWrapperPass();
614 }
615 
ModuleSummaryIndexWrapperPass()616 ModuleSummaryIndexWrapperPass::ModuleSummaryIndexWrapperPass()
617     : ModulePass(ID) {
618   initializeModuleSummaryIndexWrapperPassPass(*PassRegistry::getPassRegistry());
619 }
620 
runOnModule(Module & M)621 bool ModuleSummaryIndexWrapperPass::runOnModule(Module &M) {
622   auto &PSI = *getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
623   Index.emplace(buildModuleSummaryIndex(
624       M,
625       [this](const Function &F) {
626         return &(this->getAnalysis<BlockFrequencyInfoWrapperPass>(
627                          *const_cast<Function *>(&F))
628                      .getBFI());
629       },
630       &PSI));
631   return false;
632 }
633 
doFinalization(Module & M)634 bool ModuleSummaryIndexWrapperPass::doFinalization(Module &M) {
635   Index.reset();
636   return false;
637 }
638 
getAnalysisUsage(AnalysisUsage & AU) const639 void ModuleSummaryIndexWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
640   AU.setPreservesAll();
641   AU.addRequired<BlockFrequencyInfoWrapperPass>();
642   AU.addRequired<ProfileSummaryInfoWrapperPass>();
643 }
644