LLVM  12.0.0git
WholeProgramDevirt.cpp
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1 //===- WholeProgramDevirt.cpp - Whole program virtual call optimization ---===//
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 implements whole program optimization of virtual calls in cases
10 // where we know (via !type metadata) that the list of callees is fixed. This
11 // includes the following:
12 // - Single implementation devirtualization: if a virtual call has a single
13 // possible callee, replace all calls with a direct call to that callee.
14 // - Virtual constant propagation: if the virtual function's return type is an
15 // integer <=64 bits and all possible callees are readnone, for each class and
16 // each list of constant arguments: evaluate the function, store the return
17 // value alongside the virtual table, and rewrite each virtual call as a load
18 // from the virtual table.
19 // - Uniform return value optimization: if the conditions for virtual constant
20 // propagation hold and each function returns the same constant value, replace
21 // each virtual call with that constant.
22 // - Unique return value optimization for i1 return values: if the conditions
23 // for virtual constant propagation hold and a single vtable's function
24 // returns 0, or a single vtable's function returns 1, replace each virtual
25 // call with a comparison of the vptr against that vtable's address.
26 //
27 // This pass is intended to be used during the regular and thin LTO pipelines:
28 //
29 // During regular LTO, the pass determines the best optimization for each
30 // virtual call and applies the resolutions directly to virtual calls that are
31 // eligible for virtual call optimization (i.e. calls that use either of the
32 // llvm.assume(llvm.type.test) or llvm.type.checked.load intrinsics).
33 //
34 // During hybrid Regular/ThinLTO, the pass operates in two phases:
35 // - Export phase: this is run during the thin link over a single merged module
36 // that contains all vtables with !type metadata that participate in the link.
37 // The pass computes a resolution for each virtual call and stores it in the
38 // type identifier summary.
39 // - Import phase: this is run during the thin backends over the individual
40 // modules. The pass applies the resolutions previously computed during the
41 // import phase to each eligible virtual call.
42 //
43 // During ThinLTO, the pass operates in two phases:
44 // - Export phase: this is run during the thin link over the index which
45 // contains a summary of all vtables with !type metadata that participate in
46 // the link. It computes a resolution for each virtual call and stores it in
47 // the type identifier summary. Only single implementation devirtualization
48 // is supported.
49 // - Import phase: (same as with hybrid case above).
50 //
51 //===----------------------------------------------------------------------===//
52 
54 #include "llvm/ADT/ArrayRef.h"
55 #include "llvm/ADT/DenseMap.h"
56 #include "llvm/ADT/DenseMapInfo.h"
57 #include "llvm/ADT/DenseSet.h"
58 #include "llvm/ADT/MapVector.h"
59 #include "llvm/ADT/SmallVector.h"
60 #include "llvm/ADT/Triple.h"
68 #include "llvm/IR/Constants.h"
69 #include "llvm/IR/DataLayout.h"
70 #include "llvm/IR/DebugLoc.h"
71 #include "llvm/IR/DerivedTypes.h"
72 #include "llvm/IR/Dominators.h"
73 #include "llvm/IR/Function.h"
74 #include "llvm/IR/GlobalAlias.h"
75 #include "llvm/IR/GlobalVariable.h"
76 #include "llvm/IR/IRBuilder.h"
77 #include "llvm/IR/InstrTypes.h"
78 #include "llvm/IR/Instruction.h"
79 #include "llvm/IR/Instructions.h"
80 #include "llvm/IR/Intrinsics.h"
81 #include "llvm/IR/LLVMContext.h"
82 #include "llvm/IR/Metadata.h"
83 #include "llvm/IR/Module.h"
85 #include "llvm/InitializePasses.h"
86 #include "llvm/Pass.h"
87 #include "llvm/PassRegistry.h"
88 #include "llvm/Support/Casting.h"
90 #include "llvm/Support/Errc.h"
91 #include "llvm/Support/Error.h"
95 #include "llvm/Transforms/IPO.h"
98 #include <algorithm>
99 #include <cstddef>
100 #include <map>
101 #include <set>
102 #include <string>
103 
104 using namespace llvm;
105 using namespace wholeprogramdevirt;
106 
107 #define DEBUG_TYPE "wholeprogramdevirt"
108 
110  "wholeprogramdevirt-summary-action",
111  cl::desc("What to do with the summary when running this pass"),
112  cl::values(clEnumValN(PassSummaryAction::None, "none", "Do nothing"),
114  "Import typeid resolutions from summary and globals"),
116  "Export typeid resolutions to summary and globals")),
117  cl::Hidden);
118 
120  "wholeprogramdevirt-read-summary",
121  cl::desc(
122  "Read summary from given bitcode or YAML file before running pass"),
123  cl::Hidden);
124 
126  "wholeprogramdevirt-write-summary",
127  cl::desc("Write summary to given bitcode or YAML file after running pass. "
128  "Output file format is deduced from extension: *.bc means writing "
129  "bitcode, otherwise YAML"),
130  cl::Hidden);
131 
132 static cl::opt<unsigned>
133  ClThreshold("wholeprogramdevirt-branch-funnel-threshold", cl::Hidden,
135  cl::desc("Maximum number of call targets per "
136  "call site to enable branch funnels"));
137 
138 static cl::opt<bool>
139  PrintSummaryDevirt("wholeprogramdevirt-print-index-based", cl::Hidden,
140  cl::init(false), cl::ZeroOrMore,
141  cl::desc("Print index-based devirtualization messages"));
142 
143 /// Provide a way to force enable whole program visibility in tests.
144 /// This is needed to support legacy tests that don't contain
145 /// !vcall_visibility metadata (the mere presense of type tests
146 /// previously implied hidden visibility).
148  WholeProgramVisibility("whole-program-visibility", cl::init(false),
150  cl::desc("Enable whole program visibility"));
151 
152 /// Provide a way to force disable whole program for debugging or workarounds,
153 /// when enabled via the linker.
155  "disable-whole-program-visibility", cl::init(false), cl::Hidden,
157  cl::desc("Disable whole program visibility (overrides enabling options)"));
158 
159 /// Provide way to prevent certain function from being devirtualized
161  SkipFunctionNames("wholeprogramdevirt-skip",
162  cl::desc("Prevent function(s) from being devirtualized"),
164 
165 namespace {
166 struct PatternList {
167  std::vector<GlobPattern> Patterns;
168  template <class T> void init(const T &StringList) {
169  for (const auto &S : StringList)
171  Patterns.push_back(std::move(*Pat));
172  }
173  bool match(StringRef S) {
174  for (const GlobPattern &P : Patterns)
175  if (P.match(S))
176  return true;
177  return false;
178  }
179 };
180 } // namespace
181 
182 // Find the minimum offset that we may store a value of size Size bits at. If
183 // IsAfter is set, look for an offset before the object, otherwise look for an
184 // offset after the object.
185 uint64_t
187  bool IsAfter, uint64_t Size) {
188  // Find a minimum offset taking into account only vtable sizes.
189  uint64_t MinByte = 0;
190  for (const VirtualCallTarget &Target : Targets) {
191  if (IsAfter)
192  MinByte = std::max(MinByte, Target.minAfterBytes());
193  else
194  MinByte = std::max(MinByte, Target.minBeforeBytes());
195  }
196 
197  // Build a vector of arrays of bytes covering, for each target, a slice of the
198  // used region (see AccumBitVector::BytesUsed in
199  // llvm/Transforms/IPO/WholeProgramDevirt.h) starting at MinByte. Effectively,
200  // this aligns the used regions to start at MinByte.
201  //
202  // In this example, A, B and C are vtables, # is a byte already allocated for
203  // a virtual function pointer, AAAA... (etc.) are the used regions for the
204  // vtables and Offset(X) is the value computed for the Offset variable below
205  // for X.
206  //
207  // Offset(A)
208  // | |
209  // |MinByte
210  // A: ################AAAAAAAA|AAAAAAAA
211  // B: ########BBBBBBBBBBBBBBBB|BBBB
212  // C: ########################|CCCCCCCCCCCCCCCC
213  // | Offset(B) |
214  //
215  // This code produces the slices of A, B and C that appear after the divider
216  // at MinByte.
217  std::vector<ArrayRef<uint8_t>> Used;
218  for (const VirtualCallTarget &Target : Targets) {
219  ArrayRef<uint8_t> VTUsed = IsAfter ? Target.TM->Bits->After.BytesUsed
220  : Target.TM->Bits->Before.BytesUsed;
221  uint64_t Offset = IsAfter ? MinByte - Target.minAfterBytes()
222  : MinByte - Target.minBeforeBytes();
223 
224  // Disregard used regions that are smaller than Offset. These are
225  // effectively all-free regions that do not need to be checked.
226  if (VTUsed.size() > Offset)
227  Used.push_back(VTUsed.slice(Offset));
228  }
229 
230  if (Size == 1) {
231  // Find a free bit in each member of Used.
232  for (unsigned I = 0;; ++I) {
233  uint8_t BitsUsed = 0;
234  for (auto &&B : Used)
235  if (I < B.size())
236  BitsUsed |= B[I];
237  if (BitsUsed != 0xff)
238  return (MinByte + I) * 8 +
239  countTrailingZeros(uint8_t(~BitsUsed), ZB_Undefined);
240  }
241  } else {
242  // Find a free (Size/8) byte region in each member of Used.
243  // FIXME: see if alignment helps.
244  for (unsigned I = 0;; ++I) {
245  for (auto &&B : Used) {
246  unsigned Byte = 0;
247  while ((I + Byte) < B.size() && Byte < (Size / 8)) {
248  if (B[I + Byte])
249  goto NextI;
250  ++Byte;
251  }
252  }
253  return (MinByte + I) * 8;
254  NextI:;
255  }
256  }
257 }
258 
260  MutableArrayRef<VirtualCallTarget> Targets, uint64_t AllocBefore,
261  unsigned BitWidth, int64_t &OffsetByte, uint64_t &OffsetBit) {
262  if (BitWidth == 1)
263  OffsetByte = -(AllocBefore / 8 + 1);
264  else
265  OffsetByte = -((AllocBefore + 7) / 8 + (BitWidth + 7) / 8);
266  OffsetBit = AllocBefore % 8;
267 
268  for (VirtualCallTarget &Target : Targets) {
269  if (BitWidth == 1)
270  Target.setBeforeBit(AllocBefore);
271  else
272  Target.setBeforeBytes(AllocBefore, (BitWidth + 7) / 8);
273  }
274 }
275 
277  MutableArrayRef<VirtualCallTarget> Targets, uint64_t AllocAfter,
278  unsigned BitWidth, int64_t &OffsetByte, uint64_t &OffsetBit) {
279  if (BitWidth == 1)
280  OffsetByte = AllocAfter / 8;
281  else
282  OffsetByte = (AllocAfter + 7) / 8;
283  OffsetBit = AllocAfter % 8;
284 
285  for (VirtualCallTarget &Target : Targets) {
286  if (BitWidth == 1)
287  Target.setAfterBit(AllocAfter);
288  else
289  Target.setAfterBytes(AllocAfter, (BitWidth + 7) / 8);
290  }
291 }
292 
294  : Fn(Fn), TM(TM),
295  IsBigEndian(Fn->getParent()->getDataLayout().isBigEndian()), WasDevirt(false) {}
296 
297 namespace {
298 
299 // A slot in a set of virtual tables. The TypeID identifies the set of virtual
300 // tables, and the ByteOffset is the offset in bytes from the address point to
301 // the virtual function pointer.
302 struct VTableSlot {
303  Metadata *TypeID;
304  uint64_t ByteOffset;
305 };
306 
307 } // end anonymous namespace
308 
309 namespace llvm {
310 
311 template <> struct DenseMapInfo<VTableSlot> {
312  static VTableSlot getEmptyKey() {
315  }
316  static VTableSlot getTombstoneKey() {
319  }
320  static unsigned getHashValue(const VTableSlot &I) {
321  return DenseMapInfo<Metadata *>::getHashValue(I.TypeID) ^
323  }
324  static bool isEqual(const VTableSlot &LHS,
325  const VTableSlot &RHS) {
326  return LHS.TypeID == RHS.TypeID && LHS.ByteOffset == RHS.ByteOffset;
327  }
328 };
329 
330 template <> struct DenseMapInfo<VTableSlotSummary> {
334  }
338  }
339  static unsigned getHashValue(const VTableSlotSummary &I) {
342  }
343  static bool isEqual(const VTableSlotSummary &LHS,
344  const VTableSlotSummary &RHS) {
345  return LHS.TypeID == RHS.TypeID && LHS.ByteOffset == RHS.ByteOffset;
346  }
347 };
348 
349 } // end namespace llvm
350 
351 namespace {
352 
353 // A virtual call site. VTable is the loaded virtual table pointer, and CS is
354 // the indirect virtual call.
355 struct VirtualCallSite {
356  Value *VTable = nullptr;
357  CallBase &CB;
358 
359  // If non-null, this field points to the associated unsafe use count stored in
360  // the DevirtModule::NumUnsafeUsesForTypeTest map below. See the description
361  // of that field for details.
362  unsigned *NumUnsafeUses = nullptr;
363 
364  void
365  emitRemark(const StringRef OptName, const StringRef TargetName,
367  Function *F = CB.getCaller();
368  DebugLoc DLoc = CB.getDebugLoc();
369  BasicBlock *Block = CB.getParent();
370 
371  using namespace ore;
372  OREGetter(F).emit(OptimizationRemark(DEBUG_TYPE, OptName, DLoc, Block)
373  << NV("Optimization", OptName)
374  << ": devirtualized a call to "
375  << NV("FunctionName", TargetName));
376  }
377 
378  void replaceAndErase(
379  const StringRef OptName, const StringRef TargetName, bool RemarksEnabled,
381  Value *New) {
382  if (RemarksEnabled)
383  emitRemark(OptName, TargetName, OREGetter);
384  CB.replaceAllUsesWith(New);
385  if (auto *II = dyn_cast<InvokeInst>(&CB)) {
386  BranchInst::Create(II->getNormalDest(), &CB);
387  II->getUnwindDest()->removePredecessor(II->getParent());
388  }
389  CB.eraseFromParent();
390  // This use is no longer unsafe.
391  if (NumUnsafeUses)
392  --*NumUnsafeUses;
393  }
394 };
395 
396 // Call site information collected for a specific VTableSlot and possibly a list
397 // of constant integer arguments. The grouping by arguments is handled by the
398 // VTableSlotInfo class.
399 struct CallSiteInfo {
400  /// The set of call sites for this slot. Used during regular LTO and the
401  /// import phase of ThinLTO (as well as the export phase of ThinLTO for any
402  /// call sites that appear in the merged module itself); in each of these
403  /// cases we are directly operating on the call sites at the IR level.
404  std::vector<VirtualCallSite> CallSites;
405 
406  /// Whether all call sites represented by this CallSiteInfo, including those
407  /// in summaries, have been devirtualized. This starts off as true because a
408  /// default constructed CallSiteInfo represents no call sites.
409  bool AllCallSitesDevirted = true;
410 
411  // These fields are used during the export phase of ThinLTO and reflect
412  // information collected from function summaries.
413 
414  /// Whether any function summary contains an llvm.assume(llvm.type.test) for
415  /// this slot.
416  bool SummaryHasTypeTestAssumeUsers = false;
417 
418  /// CFI-specific: a vector containing the list of function summaries that use
419  /// the llvm.type.checked.load intrinsic and therefore will require
420  /// resolutions for llvm.type.test in order to implement CFI checks if
421  /// devirtualization was unsuccessful. If devirtualization was successful, the
422  /// pass will clear this vector by calling markDevirt(). If at the end of the
423  /// pass the vector is non-empty, we will need to add a use of llvm.type.test
424  /// to each of the function summaries in the vector.
425  std::vector<FunctionSummary *> SummaryTypeCheckedLoadUsers;
426  std::vector<FunctionSummary *> SummaryTypeTestAssumeUsers;
427 
428  bool isExported() const {
429  return SummaryHasTypeTestAssumeUsers ||
430  !SummaryTypeCheckedLoadUsers.empty();
431  }
432 
433  void addSummaryTypeCheckedLoadUser(FunctionSummary *FS) {
434  SummaryTypeCheckedLoadUsers.push_back(FS);
435  AllCallSitesDevirted = false;
436  }
437 
438  void addSummaryTypeTestAssumeUser(FunctionSummary *FS) {
439  SummaryTypeTestAssumeUsers.push_back(FS);
440  SummaryHasTypeTestAssumeUsers = true;
441  AllCallSitesDevirted = false;
442  }
443 
444  void markDevirt() {
445  AllCallSitesDevirted = true;
446 
447  // As explained in the comment for SummaryTypeCheckedLoadUsers.
448  SummaryTypeCheckedLoadUsers.clear();
449  }
450 };
451 
452 // Call site information collected for a specific VTableSlot.
453 struct VTableSlotInfo {
454  // The set of call sites which do not have all constant integer arguments
455  // (excluding "this").
456  CallSiteInfo CSInfo;
457 
458  // The set of call sites with all constant integer arguments (excluding
459  // "this"), grouped by argument list.
460  std::map<std::vector<uint64_t>, CallSiteInfo> ConstCSInfo;
461 
462  void addCallSite(Value *VTable, CallBase &CB, unsigned *NumUnsafeUses);
463 
464 private:
465  CallSiteInfo &findCallSiteInfo(CallBase &CB);
466 };
467 
468 CallSiteInfo &VTableSlotInfo::findCallSiteInfo(CallBase &CB) {
469  std::vector<uint64_t> Args;
470  auto *CBType = dyn_cast<IntegerType>(CB.getType());
471  if (!CBType || CBType->getBitWidth() > 64 || CB.arg_empty())
472  return CSInfo;
473  for (auto &&Arg : make_range(CB.arg_begin() + 1, CB.arg_end())) {
474  auto *CI = dyn_cast<ConstantInt>(Arg);
475  if (!CI || CI->getBitWidth() > 64)
476  return CSInfo;
477  Args.push_back(CI->getZExtValue());
478  }
479  return ConstCSInfo[Args];
480 }
481 
482 void VTableSlotInfo::addCallSite(Value *VTable, CallBase &CB,
483  unsigned *NumUnsafeUses) {
484  auto &CSI = findCallSiteInfo(CB);
485  CSI.AllCallSitesDevirted = false;
486  CSI.CallSites.push_back({VTable, CB, NumUnsafeUses});
487 }
488 
489 struct DevirtModule {
490  Module &M;
493 
494  ModuleSummaryIndex *ExportSummary;
495  const ModuleSummaryIndex *ImportSummary;
496 
497  IntegerType *Int8Ty;
498  PointerType *Int8PtrTy;
500  IntegerType *Int64Ty;
501  IntegerType *IntPtrTy;
502  /// Sizeless array type, used for imported vtables. This provides a signal
503  /// to analyzers that these imports may alias, as they do for example
504  /// when multiple unique return values occur in the same vtable.
505  ArrayType *Int8Arr0Ty;
506 
507  bool RemarksEnabled;
509 
511 
512  // This map keeps track of the number of "unsafe" uses of a loaded function
513  // pointer. The key is the associated llvm.type.test intrinsic call generated
514  // by this pass. An unsafe use is one that calls the loaded function pointer
515  // directly. Every time we eliminate an unsafe use (for example, by
516  // devirtualizing it or by applying virtual constant propagation), we
517  // decrement the value stored in this map. If a value reaches zero, we can
518  // eliminate the type check by RAUWing the associated llvm.type.test call with
519  // true.
520  std::map<CallInst *, unsigned> NumUnsafeUsesForTypeTest;
521  PatternList FunctionsToSkip;
522 
523  DevirtModule(Module &M, function_ref<AAResults &(Function &)> AARGetter,
525  function_ref<DominatorTree &(Function &)> LookupDomTree,
526  ModuleSummaryIndex *ExportSummary,
527  const ModuleSummaryIndex *ImportSummary)
528  : M(M), AARGetter(AARGetter), LookupDomTree(LookupDomTree),
529  ExportSummary(ExportSummary), ImportSummary(ImportSummary),
530  Int8Ty(Type::getInt8Ty(M.getContext())),
531  Int8PtrTy(Type::getInt8PtrTy(M.getContext())),
533  Int64Ty(Type::getInt64Ty(M.getContext())),
534  IntPtrTy(M.getDataLayout().getIntPtrType(M.getContext(), 0)),
535  Int8Arr0Ty(ArrayType::get(Type::getInt8Ty(M.getContext()), 0)),
536  RemarksEnabled(areRemarksEnabled()), OREGetter(OREGetter) {
537  assert(!(ExportSummary && ImportSummary));
538  FunctionsToSkip.init(SkipFunctionNames);
539  }
540 
541  bool areRemarksEnabled();
542 
543  void
544  scanTypeTestUsers(Function *TypeTestFunc,
545  DenseMap<Metadata *, std::set<TypeMemberInfo>> &TypeIdMap);
546  void scanTypeCheckedLoadUsers(Function *TypeCheckedLoadFunc);
547 
548  void buildTypeIdentifierMap(
549  std::vector<VTableBits> &Bits,
550  DenseMap<Metadata *, std::set<TypeMemberInfo>> &TypeIdMap);
551  bool
552  tryFindVirtualCallTargets(std::vector<VirtualCallTarget> &TargetsForSlot,
553  const std::set<TypeMemberInfo> &TypeMemberInfos,
554  uint64_t ByteOffset);
555 
556  void applySingleImplDevirt(VTableSlotInfo &SlotInfo, Constant *TheFn,
557  bool &IsExported);
558  bool trySingleImplDevirt(ModuleSummaryIndex *ExportSummary,
559  MutableArrayRef<VirtualCallTarget> TargetsForSlot,
560  VTableSlotInfo &SlotInfo,
562 
563  void applyICallBranchFunnel(VTableSlotInfo &SlotInfo, Constant *JT,
564  bool &IsExported);
565  void tryICallBranchFunnel(MutableArrayRef<VirtualCallTarget> TargetsForSlot,
566  VTableSlotInfo &SlotInfo,
567  WholeProgramDevirtResolution *Res, VTableSlot Slot);
568 
569  bool tryEvaluateFunctionsWithArgs(
570  MutableArrayRef<VirtualCallTarget> TargetsForSlot,
572 
573  void applyUniformRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
574  uint64_t TheRetVal);
575  bool tryUniformRetValOpt(MutableArrayRef<VirtualCallTarget> TargetsForSlot,
576  CallSiteInfo &CSInfo,
578 
579  // Returns the global symbol name that is used to export information about the
580  // given vtable slot and list of arguments.
581  std::string getGlobalName(VTableSlot Slot, ArrayRef<uint64_t> Args,
582  StringRef Name);
583 
584  bool shouldExportConstantsAsAbsoluteSymbols();
585 
586  // This function is called during the export phase to create a symbol
587  // definition containing information about the given vtable slot and list of
588  // arguments.
589  void exportGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args, StringRef Name,
590  Constant *C);
591  void exportConstant(VTableSlot Slot, ArrayRef<uint64_t> Args, StringRef Name,
592  uint32_t Const, uint32_t &Storage);
593 
594  // This function is called during the import phase to create a reference to
595  // the symbol definition created during the export phase.
596  Constant *importGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
597  StringRef Name);
598  Constant *importConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
599  StringRef Name, IntegerType *IntTy,
600  uint32_t Storage);
601 
602  Constant *getMemberAddr(const TypeMemberInfo *M);
603 
604  void applyUniqueRetValOpt(CallSiteInfo &CSInfo, StringRef FnName, bool IsOne,
605  Constant *UniqueMemberAddr);
606  bool tryUniqueRetValOpt(unsigned BitWidth,
607  MutableArrayRef<VirtualCallTarget> TargetsForSlot,
608  CallSiteInfo &CSInfo,
610  VTableSlot Slot, ArrayRef<uint64_t> Args);
611 
612  void applyVirtualConstProp(CallSiteInfo &CSInfo, StringRef FnName,
613  Constant *Byte, Constant *Bit);
614  bool tryVirtualConstProp(MutableArrayRef<VirtualCallTarget> TargetsForSlot,
615  VTableSlotInfo &SlotInfo,
616  WholeProgramDevirtResolution *Res, VTableSlot Slot);
617 
618  void rebuildGlobal(VTableBits &B);
619 
620  // Apply the summary resolution for Slot to all virtual calls in SlotInfo.
621  void importResolution(VTableSlot Slot, VTableSlotInfo &SlotInfo);
622 
623  // If we were able to eliminate all unsafe uses for a type checked load,
624  // eliminate the associated type tests by replacing them with true.
625  void removeRedundantTypeTests();
626 
627  bool run();
628 
629  // Lower the module using the action and summary passed as command line
630  // arguments. For testing purposes only.
631  static bool
632  runForTesting(Module &M, function_ref<AAResults &(Function &)> AARGetter,
634  function_ref<DominatorTree &(Function &)> LookupDomTree);
635 };
636 
637 struct DevirtIndex {
638  ModuleSummaryIndex &ExportSummary;
639  // The set in which to record GUIDs exported from their module by
640  // devirtualization, used by client to ensure they are not internalized.
641  std::set<GlobalValue::GUID> &ExportedGUIDs;
642  // A map in which to record the information necessary to locate the WPD
643  // resolution for local targets in case they are exported by cross module
644  // importing.
645  std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap;
646 
648 
649  PatternList FunctionsToSkip;
650 
651  DevirtIndex(
652  ModuleSummaryIndex &ExportSummary,
653  std::set<GlobalValue::GUID> &ExportedGUIDs,
654  std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap)
655  : ExportSummary(ExportSummary), ExportedGUIDs(ExportedGUIDs),
656  LocalWPDTargetsMap(LocalWPDTargetsMap) {
657  FunctionsToSkip.init(SkipFunctionNames);
658  }
659 
660  bool tryFindVirtualCallTargets(std::vector<ValueInfo> &TargetsForSlot,
661  const TypeIdCompatibleVtableInfo TIdInfo,
662  uint64_t ByteOffset);
663 
664  bool trySingleImplDevirt(MutableArrayRef<ValueInfo> TargetsForSlot,
665  VTableSlotSummary &SlotSummary,
666  VTableSlotInfo &SlotInfo,
668  std::set<ValueInfo> &DevirtTargets);
669 
670  void run();
671 };
672 
673 struct WholeProgramDevirt : public ModulePass {
674  static char ID;
675 
676  bool UseCommandLine = false;
677 
678  ModuleSummaryIndex *ExportSummary = nullptr;
679  const ModuleSummaryIndex *ImportSummary = nullptr;
680 
681  WholeProgramDevirt() : ModulePass(ID), UseCommandLine(true) {
683  }
684 
685  WholeProgramDevirt(ModuleSummaryIndex *ExportSummary,
686  const ModuleSummaryIndex *ImportSummary)
687  : ModulePass(ID), ExportSummary(ExportSummary),
688  ImportSummary(ImportSummary) {
690  }
691 
692  bool runOnModule(Module &M) override {
693  if (skipModule(M))
694  return false;
695 
696  // In the new pass manager, we can request the optimization
697  // remark emitter pass on a per-function-basis, which the
698  // OREGetter will do for us.
699  // In the old pass manager, this is harder, so we just build
700  // an optimization remark emitter on the fly, when we need it.
701  std::unique_ptr<OptimizationRemarkEmitter> ORE;
702  auto OREGetter = [&](Function *F) -> OptimizationRemarkEmitter & {
703  ORE = std::make_unique<OptimizationRemarkEmitter>(F);
704  return *ORE;
705  };
706 
707  auto LookupDomTree = [this](Function &F) -> DominatorTree & {
708  return this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
709  };
710 
711  if (UseCommandLine)
712  return DevirtModule::runForTesting(M, LegacyAARGetter(*this), OREGetter,
713  LookupDomTree);
714 
715  return DevirtModule(M, LegacyAARGetter(*this), OREGetter, LookupDomTree,
716  ExportSummary, ImportSummary)
717  .run();
718  }
719 
720  void getAnalysisUsage(AnalysisUsage &AU) const override {
724  }
725 };
726 
727 } // end anonymous namespace
728 
729 INITIALIZE_PASS_BEGIN(WholeProgramDevirt, "wholeprogramdevirt",
730  "Whole program devirtualization", false, false)
735  "Whole program devirtualization", false, false)
736 char WholeProgramDevirt::ID = 0;
737 
738 ModulePass *
740  const ModuleSummaryIndex *ImportSummary) {
741  return new WholeProgramDevirt(ExportSummary, ImportSummary);
742 }
743 
745  ModuleAnalysisManager &AM) {
746  auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
747  auto AARGetter = [&](Function &F) -> AAResults & {
748  return FAM.getResult<AAManager>(F);
749  };
750  auto OREGetter = [&](Function *F) -> OptimizationRemarkEmitter & {
751  return FAM.getResult<OptimizationRemarkEmitterAnalysis>(*F);
752  };
753  auto LookupDomTree = [&FAM](Function &F) -> DominatorTree & {
754  return FAM.getResult<DominatorTreeAnalysis>(F);
755  };
756  if (!DevirtModule(M, AARGetter, OREGetter, LookupDomTree, ExportSummary,
757  ImportSummary)
758  .run())
759  return PreservedAnalyses::all();
760  return PreservedAnalyses::none();
761 }
762 
763 // Enable whole program visibility if enabled by client (e.g. linker) or
764 // internal option, and not force disabled.
765 static bool hasWholeProgramVisibility(bool WholeProgramVisibilityEnabledInLTO) {
766  return (WholeProgramVisibilityEnabledInLTO || WholeProgramVisibility) &&
768 }
769 
770 namespace llvm {
771 
772 /// If whole program visibility asserted, then upgrade all public vcall
773 /// visibility metadata on vtable definitions to linkage unit visibility in
774 /// Module IR (for regular or hybrid LTO).
776  bool WholeProgramVisibilityEnabledInLTO) {
777  if (!hasWholeProgramVisibility(WholeProgramVisibilityEnabledInLTO))
778  return;
779  for (GlobalVariable &GV : M.globals())
780  // Add linkage unit visibility to any variable with type metadata, which are
781  // the vtable definitions. We won't have an existing vcall_visibility
782  // metadata on vtable definitions with public visibility.
783  if (GV.hasMetadata(LLVMContext::MD_type) &&
784  GV.getVCallVisibility() == GlobalObject::VCallVisibilityPublic)
785  GV.setVCallVisibilityMetadata(GlobalObject::VCallVisibilityLinkageUnit);
786 }
787 
788 /// If whole program visibility asserted, then upgrade all public vcall
789 /// visibility metadata on vtable definition summaries to linkage unit
790 /// visibility in Module summary index (for ThinLTO).
792  bool WholeProgramVisibilityEnabledInLTO) {
793  if (!hasWholeProgramVisibility(WholeProgramVisibilityEnabledInLTO))
794  return;
795  for (auto &P : Index) {
796  for (auto &S : P.second.SummaryList) {
797  auto *GVar = dyn_cast<GlobalVarSummary>(S.get());
798  if (!GVar || GVar->vTableFuncs().empty() ||
799  GVar->getVCallVisibility() != GlobalObject::VCallVisibilityPublic)
800  continue;
802  }
803  }
804 }
805 
807  ModuleSummaryIndex &Summary, std::set<GlobalValue::GUID> &ExportedGUIDs,
808  std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap) {
809  DevirtIndex(Summary, ExportedGUIDs, LocalWPDTargetsMap).run();
810 }
811 
813  ModuleSummaryIndex &Summary,
814  function_ref<bool(StringRef, ValueInfo)> isExported,
815  std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap) {
816  for (auto &T : LocalWPDTargetsMap) {
817  auto &VI = T.first;
818  // This was enforced earlier during trySingleImplDevirt.
819  assert(VI.getSummaryList().size() == 1 &&
820  "Devirt of local target has more than one copy");
821  auto &S = VI.getSummaryList()[0];
822  if (!isExported(S->modulePath(), VI))
823  continue;
824 
825  // It's been exported by a cross module import.
826  for (auto &SlotSummary : T.second) {
827  auto *TIdSum = Summary.getTypeIdSummary(SlotSummary.TypeID);
828  assert(TIdSum);
829  auto WPDRes = TIdSum->WPDRes.find(SlotSummary.ByteOffset);
830  assert(WPDRes != TIdSum->WPDRes.end());
831  WPDRes->second.SingleImplName = ModuleSummaryIndex::getGlobalNameForLocal(
832  WPDRes->second.SingleImplName,
833  Summary.getModuleHash(S->modulePath()));
834  }
835  }
836 }
837 
838 } // end namespace llvm
839 
841  // Check that summary index contains regular LTO module when performing
842  // export to prevent occasional use of index from pure ThinLTO compilation
843  // (-fno-split-lto-module). This kind of summary index is passed to
844  // DevirtIndex::run, not to DevirtModule::run used by opt/runForTesting.
845  const auto &ModPaths = Summary->modulePaths();
848  ModPaths.end())
849  return createStringError(
851  "combined summary should contain Regular LTO module");
852  return ErrorSuccess();
853 }
854 
855 bool DevirtModule::runForTesting(
856  Module &M, function_ref<AAResults &(Function &)> AARGetter,
858  function_ref<DominatorTree &(Function &)> LookupDomTree) {
859  std::unique_ptr<ModuleSummaryIndex> Summary =
860  std::make_unique<ModuleSummaryIndex>(/*HaveGVs=*/false);
861 
862  // Handle the command-line summary arguments. This code is for testing
863  // purposes only, so we handle errors directly.
864  if (!ClReadSummary.empty()) {
865  ExitOnError ExitOnErr("-wholeprogramdevirt-read-summary: " + ClReadSummary +
866  ": ");
867  auto ReadSummaryFile =
869  if (Expected<std::unique_ptr<ModuleSummaryIndex>> SummaryOrErr =
870  getModuleSummaryIndex(*ReadSummaryFile)) {
871  Summary = std::move(*SummaryOrErr);
872  ExitOnErr(checkCombinedSummaryForTesting(Summary.get()));
873  } else {
874  // Try YAML if we've failed with bitcode.
875  consumeError(SummaryOrErr.takeError());
876  yaml::Input In(ReadSummaryFile->getBuffer());
877  In >> *Summary;
878  ExitOnErr(errorCodeToError(In.error()));
879  }
880  }
881 
882  bool Changed =
883  DevirtModule(M, AARGetter, OREGetter, LookupDomTree,
884  ClSummaryAction == PassSummaryAction::Export ? Summary.get()
885  : nullptr,
886  ClSummaryAction == PassSummaryAction::Import ? Summary.get()
887  : nullptr)
888  .run();
889 
890  if (!ClWriteSummary.empty()) {
891  ExitOnError ExitOnErr(
892  "-wholeprogramdevirt-write-summary: " + ClWriteSummary + ": ");
893  std::error_code EC;
894  if (StringRef(ClWriteSummary).endswith(".bc")) {
896  ExitOnErr(errorCodeToError(EC));
897  WriteIndexToFile(*Summary, OS);
898  } else {
900  ExitOnErr(errorCodeToError(EC));
901  yaml::Output Out(OS);
902  Out << *Summary;
903  }
904  }
905 
906  return Changed;
907 }
908 
909 void DevirtModule::buildTypeIdentifierMap(
910  std::vector<VTableBits> &Bits,
911  DenseMap<Metadata *, std::set<TypeMemberInfo>> &TypeIdMap) {
913  Bits.reserve(M.getGlobalList().size());
915  for (GlobalVariable &GV : M.globals()) {
916  Types.clear();
917  GV.getMetadata(LLVMContext::MD_type, Types);
918  if (GV.isDeclaration() || Types.empty())
919  continue;
920 
921  VTableBits *&BitsPtr = GVToBits[&GV];
922  if (!BitsPtr) {
923  Bits.emplace_back();
924  Bits.back().GV = &GV;
925  Bits.back().ObjectSize =
926  M.getDataLayout().getTypeAllocSize(GV.getInitializer()->getType());
927  BitsPtr = &Bits.back();
928  }
929 
930  for (MDNode *Type : Types) {
931  auto TypeID = Type->getOperand(1).get();
932 
933  uint64_t Offset =
934  cast<ConstantInt>(
935  cast<ConstantAsMetadata>(Type->getOperand(0))->getValue())
936  ->getZExtValue();
937 
938  TypeIdMap[TypeID].insert({BitsPtr, Offset});
939  }
940  }
941 }
942 
943 bool DevirtModule::tryFindVirtualCallTargets(
944  std::vector<VirtualCallTarget> &TargetsForSlot,
945  const std::set<TypeMemberInfo> &TypeMemberInfos, uint64_t ByteOffset) {
946  for (const TypeMemberInfo &TM : TypeMemberInfos) {
947  if (!TM.Bits->GV->isConstant())
948  return false;
949 
950  // We cannot perform whole program devirtualization analysis on a vtable
951  // with public LTO visibility.
952  if (TM.Bits->GV->getVCallVisibility() ==
954  return false;
955 
957  TM.Offset + ByteOffset, M);
958  if (!Ptr)
959  return false;
960 
961  auto Fn = dyn_cast<Function>(Ptr->stripPointerCasts());
962  if (!Fn)
963  return false;
964 
965  if (FunctionsToSkip.match(Fn->getName()))
966  return false;
967 
968  // We can disregard __cxa_pure_virtual as a possible call target, as
969  // calls to pure virtuals are UB.
970  if (Fn->getName() == "__cxa_pure_virtual")
971  continue;
972 
973  TargetsForSlot.push_back({Fn, &TM});
974  }
975 
976  // Give up if we couldn't find any targets.
977  return !TargetsForSlot.empty();
978 }
979 
980 bool DevirtIndex::tryFindVirtualCallTargets(
981  std::vector<ValueInfo> &TargetsForSlot, const TypeIdCompatibleVtableInfo TIdInfo,
982  uint64_t ByteOffset) {
983  for (const TypeIdOffsetVtableInfo &P : TIdInfo) {
984  // Find the first non-available_externally linkage vtable initializer.
985  // We can have multiple available_externally, linkonce_odr and weak_odr
986  // vtable initializers, however we want to skip available_externally as they
987  // do not have type metadata attached, and therefore the summary will not
988  // contain any vtable functions. We can also have multiple external
989  // vtable initializers in the case of comdats, which we cannot check here.
990  // The linker should give an error in this case.
991  //
992  // Also, handle the case of same-named local Vtables with the same path
993  // and therefore the same GUID. This can happen if there isn't enough
994  // distinguishing path when compiling the source file. In that case we
995  // conservatively return false early.
996  const GlobalVarSummary *VS = nullptr;
997  bool LocalFound = false;
998  for (auto &S : P.VTableVI.getSummaryList()) {
999  if (GlobalValue::isLocalLinkage(S->linkage())) {
1000  if (LocalFound)
1001  return false;
1002  LocalFound = true;
1003  }
1004  if (!GlobalValue::isAvailableExternallyLinkage(S->linkage())) {
1005  VS = cast<GlobalVarSummary>(S->getBaseObject());
1006  // We cannot perform whole program devirtualization analysis on a vtable
1007  // with public LTO visibility.
1009  return false;
1010  }
1011  }
1012  if (!VS->isLive())
1013  continue;
1014  for (auto VTP : VS->vTableFuncs()) {
1015  if (VTP.VTableOffset != P.AddressPointOffset + ByteOffset)
1016  continue;
1017 
1018  TargetsForSlot.push_back(VTP.FuncVI);
1019  }
1020  }
1021 
1022  // Give up if we couldn't find any targets.
1023  return !TargetsForSlot.empty();
1024 }
1025 
1026 void DevirtModule::applySingleImplDevirt(VTableSlotInfo &SlotInfo,
1027  Constant *TheFn, bool &IsExported) {
1028  auto Apply = [&](CallSiteInfo &CSInfo) {
1029  for (auto &&VCallSite : CSInfo.CallSites) {
1030  if (RemarksEnabled)
1031  VCallSite.emitRemark("single-impl",
1032  TheFn->stripPointerCasts()->getName(), OREGetter);
1033  VCallSite.CB.setCalledOperand(ConstantExpr::getBitCast(
1034  TheFn, VCallSite.CB.getCalledOperand()->getType()));
1035  // This use is no longer unsafe.
1036  if (VCallSite.NumUnsafeUses)
1037  --*VCallSite.NumUnsafeUses;
1038  }
1039  if (CSInfo.isExported())
1040  IsExported = true;
1041  CSInfo.markDevirt();
1042  };
1043  Apply(SlotInfo.CSInfo);
1044  for (auto &P : SlotInfo.ConstCSInfo)
1045  Apply(P.second);
1046 }
1047 
1048 static bool AddCalls(VTableSlotInfo &SlotInfo, const ValueInfo &Callee) {
1049  // We can't add calls if we haven't seen a definition
1050  if (Callee.getSummaryList().empty())
1051  return false;
1052 
1053  // Insert calls into the summary index so that the devirtualized targets
1054  // are eligible for import.
1055  // FIXME: Annotate type tests with hotness. For now, mark these as hot
1056  // to better ensure we have the opportunity to inline them.
1057  bool IsExported = false;
1058  auto &S = Callee.getSummaryList()[0];
1059  CalleeInfo CI(CalleeInfo::HotnessType::Hot, /* RelBF = */ 0);
1060  auto AddCalls = [&](CallSiteInfo &CSInfo) {
1061  for (auto *FS : CSInfo.SummaryTypeCheckedLoadUsers) {
1062  FS->addCall({Callee, CI});
1063  IsExported |= S->modulePath() != FS->modulePath();
1064  }
1065  for (auto *FS : CSInfo.SummaryTypeTestAssumeUsers) {
1066  FS->addCall({Callee, CI});
1067  IsExported |= S->modulePath() != FS->modulePath();
1068  }
1069  };
1070  AddCalls(SlotInfo.CSInfo);
1071  for (auto &P : SlotInfo.ConstCSInfo)
1072  AddCalls(P.second);
1073  return IsExported;
1074 }
1075 
1076 bool DevirtModule::trySingleImplDevirt(
1077  ModuleSummaryIndex *ExportSummary,
1078  MutableArrayRef<VirtualCallTarget> TargetsForSlot, VTableSlotInfo &SlotInfo,
1080  // See if the program contains a single implementation of this virtual
1081  // function.
1082  Function *TheFn = TargetsForSlot[0].Fn;
1083  for (auto &&Target : TargetsForSlot)
1084  if (TheFn != Target.Fn)
1085  return false;
1086 
1087  // If so, update each call site to call that implementation directly.
1088  if (RemarksEnabled)
1089  TargetsForSlot[0].WasDevirt = true;
1090 
1091  bool IsExported = false;
1092  applySingleImplDevirt(SlotInfo, TheFn, IsExported);
1093  if (!IsExported)
1094  return false;
1095 
1096  // If the only implementation has local linkage, we must promote to external
1097  // to make it visible to thin LTO objects. We can only get here during the
1098  // ThinLTO export phase.
1099  if (TheFn->hasLocalLinkage()) {
1100  std::string NewName = (TheFn->getName() + "$merged").str();
1101 
1102  // Since we are renaming the function, any comdats with the same name must
1103  // also be renamed. This is required when targeting COFF, as the comdat name
1104  // must match one of the names of the symbols in the comdat.
1105  if (Comdat *C = TheFn->getComdat()) {
1106  if (C->getName() == TheFn->getName()) {
1107  Comdat *NewC = M.getOrInsertComdat(NewName);
1108  NewC->setSelectionKind(C->getSelectionKind());
1109  for (GlobalObject &GO : M.global_objects())
1110  if (GO.getComdat() == C)
1111  GO.setComdat(NewC);
1112  }
1113  }
1114 
1117  TheFn->setName(NewName);
1118  }
1119  if (ValueInfo TheFnVI = ExportSummary->getValueInfo(TheFn->getGUID()))
1120  // Any needed promotion of 'TheFn' has already been done during
1121  // LTO unit split, so we can ignore return value of AddCalls.
1122  AddCalls(SlotInfo, TheFnVI);
1123 
1125  Res->SingleImplName = std::string(TheFn->getName());
1126 
1127  return true;
1128 }
1129 
1130 bool DevirtIndex::trySingleImplDevirt(MutableArrayRef<ValueInfo> TargetsForSlot,
1131  VTableSlotSummary &SlotSummary,
1132  VTableSlotInfo &SlotInfo,
1134  std::set<ValueInfo> &DevirtTargets) {
1135  // See if the program contains a single implementation of this virtual
1136  // function.
1137  auto TheFn = TargetsForSlot[0];
1138  for (auto &&Target : TargetsForSlot)
1139  if (TheFn != Target)
1140  return false;
1141 
1142  // Don't devirtualize if we don't have target definition.
1143  auto Size = TheFn.getSummaryList().size();
1144  if (!Size)
1145  return false;
1146 
1147  // Don't devirtualize function if we're told to skip it
1148  // in -wholeprogramdevirt-skip.
1149  if (FunctionsToSkip.match(TheFn.name()))
1150  return false;
1151 
1152  // If the summary list contains multiple summaries where at least one is
1153  // a local, give up, as we won't know which (possibly promoted) name to use.
1154  for (auto &S : TheFn.getSummaryList())
1155  if (GlobalValue::isLocalLinkage(S->linkage()) && Size > 1)
1156  return false;
1157 
1158  // Collect functions devirtualized at least for one call site for stats.
1159  if (PrintSummaryDevirt)
1160  DevirtTargets.insert(TheFn);
1161 
1162  auto &S = TheFn.getSummaryList()[0];
1163  bool IsExported = AddCalls(SlotInfo, TheFn);
1164  if (IsExported)
1165  ExportedGUIDs.insert(TheFn.getGUID());
1166 
1167  // Record in summary for use in devirtualization during the ThinLTO import
1168  // step.
1170  if (GlobalValue::isLocalLinkage(S->linkage())) {
1171  if (IsExported)
1172  // If target is a local function and we are exporting it by
1173  // devirtualizing a call in another module, we need to record the
1174  // promoted name.
1176  TheFn.name(), ExportSummary.getModuleHash(S->modulePath()));
1177  else {
1178  LocalWPDTargetsMap[TheFn].push_back(SlotSummary);
1179  Res->SingleImplName = std::string(TheFn.name());
1180  }
1181  } else
1182  Res->SingleImplName = std::string(TheFn.name());
1183 
1184  // Name will be empty if this thin link driven off of serialized combined
1185  // index (e.g. llvm-lto). However, WPD is not supported/invoked for the
1186  // legacy LTO API anyway.
1187  assert(!Res->SingleImplName.empty());
1188 
1189  return true;
1190 }
1191 
1192 void DevirtModule::tryICallBranchFunnel(
1193  MutableArrayRef<VirtualCallTarget> TargetsForSlot, VTableSlotInfo &SlotInfo,
1194  WholeProgramDevirtResolution *Res, VTableSlot Slot) {
1195  Triple T(M.getTargetTriple());
1196  if (T.getArch() != Triple::x86_64)
1197  return;
1198 
1199  if (TargetsForSlot.size() > ClThreshold)
1200  return;
1201 
1202  bool HasNonDevirt = !SlotInfo.CSInfo.AllCallSitesDevirted;
1203  if (!HasNonDevirt)
1204  for (auto &P : SlotInfo.ConstCSInfo)
1205  if (!P.second.AllCallSitesDevirted) {
1206  HasNonDevirt = true;
1207  break;
1208  }
1209 
1210  if (!HasNonDevirt)
1211  return;
1212 
1213  FunctionType *FT =
1214  FunctionType::get(Type::getVoidTy(M.getContext()), {Int8PtrTy}, true);
1215  Function *JT;
1216  if (isa<MDString>(Slot.TypeID)) {
1219  getGlobalName(Slot, {}, "branch_funnel"), &M);
1220  JT->setVisibility(GlobalValue::HiddenVisibility);
1221  } else {
1224  "branch_funnel", &M);
1225  }
1226  JT->addAttribute(1, Attribute::Nest);
1227 
1228  std::vector<Value *> JTArgs;
1229  JTArgs.push_back(JT->arg_begin());
1230  for (auto &T : TargetsForSlot) {
1231  JTArgs.push_back(getMemberAddr(T.TM));
1232  JTArgs.push_back(T.Fn);
1233  }
1234 
1235  BasicBlock *BB = BasicBlock::Create(M.getContext(), "", JT, nullptr);
1236  Function *Intr =
1237  Intrinsic::getDeclaration(&M, llvm::Intrinsic::icall_branch_funnel, {});
1238 
1239  auto *CI = CallInst::Create(Intr, JTArgs, "", BB);
1240  CI->setTailCallKind(CallInst::TCK_MustTail);
1241  ReturnInst::Create(M.getContext(), nullptr, BB);
1242 
1243  bool IsExported = false;
1244  applyICallBranchFunnel(SlotInfo, JT, IsExported);
1245  if (IsExported)
1247 }
1248 
1249 void DevirtModule::applyICallBranchFunnel(VTableSlotInfo &SlotInfo,
1250  Constant *JT, bool &IsExported) {
1251  auto Apply = [&](CallSiteInfo &CSInfo) {
1252  if (CSInfo.isExported())
1253  IsExported = true;
1254  if (CSInfo.AllCallSitesDevirted)
1255  return;
1256  for (auto &&VCallSite : CSInfo.CallSites) {
1257  CallBase &CB = VCallSite.CB;
1258 
1259  // Jump tables are only profitable if the retpoline mitigation is enabled.
1260  Attribute FSAttr = CB.getCaller()->getFnAttribute("target-features");
1261  if (FSAttr.hasAttribute(Attribute::None) ||
1262  !FSAttr.getValueAsString().contains("+retpoline"))
1263  continue;
1264 
1265  if (RemarksEnabled)
1266  VCallSite.emitRemark("branch-funnel",
1267  JT->stripPointerCasts()->getName(), OREGetter);
1268 
1269  // Pass the address of the vtable in the nest register, which is r10 on
1270  // x86_64.
1271  std::vector<Type *> NewArgs;
1272  NewArgs.push_back(Int8PtrTy);
1273  for (Type *T : CB.getFunctionType()->params())
1274  NewArgs.push_back(T);
1275  FunctionType *NewFT =
1277  CB.getFunctionType()->isVarArg());
1278  PointerType *NewFTPtr = PointerType::getUnqual(NewFT);
1279 
1280  IRBuilder<> IRB(&CB);
1281  std::vector<Value *> Args;
1282  Args.push_back(IRB.CreateBitCast(VCallSite.VTable, Int8PtrTy));
1283  Args.insert(Args.end(), CB.arg_begin(), CB.arg_end());
1284 
1285  CallBase *NewCS = nullptr;
1286  if (isa<CallInst>(CB))
1287  NewCS = IRB.CreateCall(NewFT, IRB.CreateBitCast(JT, NewFTPtr), Args);
1288  else
1289  NewCS = IRB.CreateInvoke(NewFT, IRB.CreateBitCast(JT, NewFTPtr),
1290  cast<InvokeInst>(CB).getNormalDest(),
1291  cast<InvokeInst>(CB).getUnwindDest(), Args);
1292  NewCS->setCallingConv(CB.getCallingConv());
1293 
1295  std::vector<AttributeSet> NewArgAttrs;
1296  NewArgAttrs.push_back(AttributeSet::get(
1298  M.getContext(), Attribute::Nest)}));
1299  for (unsigned I = 0; I + 2 < Attrs.getNumAttrSets(); ++I)
1300  NewArgAttrs.push_back(Attrs.getParamAttributes(I));
1301  NewCS->setAttributes(
1303  Attrs.getRetAttributes(), NewArgAttrs));
1304 
1305  CB.replaceAllUsesWith(NewCS);
1306  CB.eraseFromParent();
1307 
1308  // This use is no longer unsafe.
1309  if (VCallSite.NumUnsafeUses)
1310  --*VCallSite.NumUnsafeUses;
1311  }
1312  // Don't mark as devirtualized because there may be callers compiled without
1313  // retpoline mitigation, which would mean that they are lowered to
1314  // llvm.type.test and therefore require an llvm.type.test resolution for the
1315  // type identifier.
1316  };
1317  Apply(SlotInfo.CSInfo);
1318  for (auto &P : SlotInfo.ConstCSInfo)
1319  Apply(P.second);
1320 }
1321 
1322 bool DevirtModule::tryEvaluateFunctionsWithArgs(
1323  MutableArrayRef<VirtualCallTarget> TargetsForSlot,
1325  // Evaluate each function and store the result in each target's RetVal
1326  // field.
1327  for (VirtualCallTarget &Target : TargetsForSlot) {
1328  if (Target.Fn->arg_size() != Args.size() + 1)
1329  return false;
1330 
1331  Evaluator Eval(M.getDataLayout(), nullptr);
1332  SmallVector<Constant *, 2> EvalArgs;
1333  EvalArgs.push_back(
1334  Constant::getNullValue(Target.Fn->getFunctionType()->getParamType(0)));
1335  for (unsigned I = 0; I != Args.size(); ++I) {
1336  auto *ArgTy = dyn_cast<IntegerType>(
1337  Target.Fn->getFunctionType()->getParamType(I + 1));
1338  if (!ArgTy)
1339  return false;
1340  EvalArgs.push_back(ConstantInt::get(ArgTy, Args[I]));
1341  }
1342 
1343  Constant *RetVal;
1344  if (!Eval.EvaluateFunction(Target.Fn, RetVal, EvalArgs) ||
1345  !isa<ConstantInt>(RetVal))
1346  return false;
1347  Target.RetVal = cast<ConstantInt>(RetVal)->getZExtValue();
1348  }
1349  return true;
1350 }
1351 
1352 void DevirtModule::applyUniformRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
1353  uint64_t TheRetVal) {
1354  for (auto Call : CSInfo.CallSites)
1355  Call.replaceAndErase(
1356  "uniform-ret-val", FnName, RemarksEnabled, OREGetter,
1357  ConstantInt::get(cast<IntegerType>(Call.CB.getType()), TheRetVal));
1358  CSInfo.markDevirt();
1359 }
1360 
1361 bool DevirtModule::tryUniformRetValOpt(
1362  MutableArrayRef<VirtualCallTarget> TargetsForSlot, CallSiteInfo &CSInfo,
1364  // Uniform return value optimization. If all functions return the same
1365  // constant, replace all calls with that constant.
1366  uint64_t TheRetVal = TargetsForSlot[0].RetVal;
1367  for (const VirtualCallTarget &Target : TargetsForSlot)
1368  if (Target.RetVal != TheRetVal)
1369  return false;
1370 
1371  if (CSInfo.isExported()) {
1373  Res->Info = TheRetVal;
1374  }
1375 
1376  applyUniformRetValOpt(CSInfo, TargetsForSlot[0].Fn->getName(), TheRetVal);
1377  if (RemarksEnabled)
1378  for (auto &&Target : TargetsForSlot)
1379  Target.WasDevirt = true;
1380  return true;
1381 }
1382 
1383 std::string DevirtModule::getGlobalName(VTableSlot Slot,
1384  ArrayRef<uint64_t> Args,
1385  StringRef Name) {
1386  std::string FullName = "__typeid_";
1387  raw_string_ostream OS(FullName);
1388  OS << cast<MDString>(Slot.TypeID)->getString() << '_' << Slot.ByteOffset;
1389  for (uint64_t Arg : Args)
1390  OS << '_' << Arg;
1391  OS << '_' << Name;
1392  return OS.str();
1393 }
1394 
1395 bool DevirtModule::shouldExportConstantsAsAbsoluteSymbols() {
1396  Triple T(M.getTargetTriple());
1397  return T.isX86() && T.getObjectFormat() == Triple::ELF;
1398 }
1399 
1400 void DevirtModule::exportGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
1401  StringRef Name, Constant *C) {
1403  getGlobalName(Slot, Args, Name), C, &M);
1405 }
1406 
1407 void DevirtModule::exportConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
1408  StringRef Name, uint32_t Const,
1409  uint32_t &Storage) {
1410  if (shouldExportConstantsAsAbsoluteSymbols()) {
1411  exportGlobal(
1412  Slot, Args, Name,
1413  ConstantExpr::getIntToPtr(ConstantInt::get(Int32Ty, Const), Int8PtrTy));
1414  return;
1415  }
1416 
1417  Storage = Const;
1418 }
1419 
1420 Constant *DevirtModule::importGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
1421  StringRef Name) {
1422  Constant *C =
1423  M.getOrInsertGlobal(getGlobalName(Slot, Args, Name), Int8Arr0Ty);
1424  auto *GV = dyn_cast<GlobalVariable>(C);
1425  if (GV)
1427  return C;
1428 }
1429 
1430 Constant *DevirtModule::importConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
1431  StringRef Name, IntegerType *IntTy,
1432  uint32_t Storage) {
1433  if (!shouldExportConstantsAsAbsoluteSymbols())
1434  return ConstantInt::get(IntTy, Storage);
1435 
1436  Constant *C = importGlobal(Slot, Args, Name);
1437  auto *GV = cast<GlobalVariable>(C->stripPointerCasts());
1438  C = ConstantExpr::getPtrToInt(C, IntTy);
1439 
1440  // We only need to set metadata if the global is newly created, in which
1441  // case it would not have hidden visibility.
1442  if (GV->hasMetadata(LLVMContext::MD_absolute_symbol))
1443  return C;
1444 
1445  auto SetAbsRange = [&](uint64_t Min, uint64_t Max) {
1446  auto *MinC = ConstantAsMetadata::get(ConstantInt::get(IntPtrTy, Min));
1447  auto *MaxC = ConstantAsMetadata::get(ConstantInt::get(IntPtrTy, Max));
1448  GV->setMetadata(LLVMContext::MD_absolute_symbol,
1449  MDNode::get(M.getContext(), {MinC, MaxC}));
1450  };
1451  unsigned AbsWidth = IntTy->getBitWidth();
1452  if (AbsWidth == IntPtrTy->getBitWidth())
1453  SetAbsRange(~0ull, ~0ull); // Full set.
1454  else
1455  SetAbsRange(0, 1ull << AbsWidth);
1456  return C;
1457 }
1458 
1459 void DevirtModule::applyUniqueRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
1460  bool IsOne,
1461  Constant *UniqueMemberAddr) {
1462  for (auto &&Call : CSInfo.CallSites) {
1463  IRBuilder<> B(&Call.CB);
1464  Value *Cmp =
1465  B.CreateICmp(IsOne ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE, Call.VTable,
1466  B.CreateBitCast(UniqueMemberAddr, Call.VTable->getType()));
1467  Cmp = B.CreateZExt(Cmp, Call.CB.getType());
1468  Call.replaceAndErase("unique-ret-val", FnName, RemarksEnabled, OREGetter,
1469  Cmp);
1470  }
1471  CSInfo.markDevirt();
1472 }
1473 
1474 Constant *DevirtModule::getMemberAddr(const TypeMemberInfo *M) {
1475  Constant *C = ConstantExpr::getBitCast(M->Bits->GV, Int8PtrTy);
1476  return ConstantExpr::getGetElementPtr(Int8Ty, C,
1477  ConstantInt::get(Int64Ty, M->Offset));
1478 }
1479 
1480 bool DevirtModule::tryUniqueRetValOpt(
1481  unsigned BitWidth, MutableArrayRef<VirtualCallTarget> TargetsForSlot,
1482  CallSiteInfo &CSInfo, WholeProgramDevirtResolution::ByArg *Res,
1483  VTableSlot Slot, ArrayRef<uint64_t> Args) {
1484  // IsOne controls whether we look for a 0 or a 1.
1485  auto tryUniqueRetValOptFor = [&](bool IsOne) {
1486  const TypeMemberInfo *UniqueMember = nullptr;
1487  for (const VirtualCallTarget &Target : TargetsForSlot) {
1488  if (Target.RetVal == (IsOne ? 1 : 0)) {
1489  if (UniqueMember)
1490  return false;
1491  UniqueMember = Target.TM;
1492  }
1493  }
1494 
1495  // We should have found a unique member or bailed out by now. We already
1496  // checked for a uniform return value in tryUniformRetValOpt.
1497  assert(UniqueMember);
1498 
1499  Constant *UniqueMemberAddr = getMemberAddr(UniqueMember);
1500  if (CSInfo.isExported()) {
1502  Res->Info = IsOne;
1503 
1504  exportGlobal(Slot, Args, "unique_member", UniqueMemberAddr);
1505  }
1506 
1507  // Replace each call with the comparison.
1508  applyUniqueRetValOpt(CSInfo, TargetsForSlot[0].Fn->getName(), IsOne,
1509  UniqueMemberAddr);
1510 
1511  // Update devirtualization statistics for targets.
1512  if (RemarksEnabled)
1513  for (auto &&Target : TargetsForSlot)
1514  Target.WasDevirt = true;
1515 
1516  return true;
1517  };
1518 
1519  if (BitWidth == 1) {
1520  if (tryUniqueRetValOptFor(true))
1521  return true;
1522  if (tryUniqueRetValOptFor(false))
1523  return true;
1524  }
1525  return false;
1526 }
1527 
1528 void DevirtModule::applyVirtualConstProp(CallSiteInfo &CSInfo, StringRef FnName,
1529  Constant *Byte, Constant *Bit) {
1530  for (auto Call : CSInfo.CallSites) {
1531  auto *RetType = cast<IntegerType>(Call.CB.getType());
1532  IRBuilder<> B(&Call.CB);
1533  Value *Addr =
1534  B.CreateGEP(Int8Ty, B.CreateBitCast(Call.VTable, Int8PtrTy), Byte);
1535  if (RetType->getBitWidth() == 1) {
1536  Value *Bits = B.CreateLoad(Int8Ty, Addr);
1537  Value *BitsAndBit = B.CreateAnd(Bits, Bit);
1538  auto IsBitSet = B.CreateICmpNE(BitsAndBit, ConstantInt::get(Int8Ty, 0));
1539  Call.replaceAndErase("virtual-const-prop-1-bit", FnName, RemarksEnabled,
1540  OREGetter, IsBitSet);
1541  } else {
1542  Value *ValAddr = B.CreateBitCast(Addr, RetType->getPointerTo());
1543  Value *Val = B.CreateLoad(RetType, ValAddr);
1544  Call.replaceAndErase("virtual-const-prop", FnName, RemarksEnabled,
1545  OREGetter, Val);
1546  }
1547  }
1548  CSInfo.markDevirt();
1549 }
1550 
1551 bool DevirtModule::tryVirtualConstProp(
1552  MutableArrayRef<VirtualCallTarget> TargetsForSlot, VTableSlotInfo &SlotInfo,
1553  WholeProgramDevirtResolution *Res, VTableSlot Slot) {
1554  // This only works if the function returns an integer.
1555  auto RetType = dyn_cast<IntegerType>(TargetsForSlot[0].Fn->getReturnType());
1556  if (!RetType)
1557  return false;
1558  unsigned BitWidth = RetType->getBitWidth();
1559  if (BitWidth > 64)
1560  return false;
1561 
1562  // Make sure that each function is defined, does not access memory, takes at
1563  // least one argument, does not use its first argument (which we assume is
1564  // 'this'), and has the same return type.
1565  //
1566  // Note that we test whether this copy of the function is readnone, rather
1567  // than testing function attributes, which must hold for any copy of the
1568  // function, even a less optimized version substituted at link time. This is
1569  // sound because the virtual constant propagation optimizations effectively
1570  // inline all implementations of the virtual function into each call site,
1571  // rather than using function attributes to perform local optimization.
1572  for (VirtualCallTarget &Target : TargetsForSlot) {
1573  if (Target.Fn->isDeclaration() ||
1574  computeFunctionBodyMemoryAccess(*Target.Fn, AARGetter(*Target.Fn)) !=
1575  MAK_ReadNone ||
1576  Target.Fn->arg_empty() || !Target.Fn->arg_begin()->use_empty() ||
1577  Target.Fn->getReturnType() != RetType)
1578  return false;
1579  }
1580 
1581  for (auto &&CSByConstantArg : SlotInfo.ConstCSInfo) {
1582  if (!tryEvaluateFunctionsWithArgs(TargetsForSlot, CSByConstantArg.first))
1583  continue;
1584 
1585  WholeProgramDevirtResolution::ByArg *ResByArg = nullptr;
1586  if (Res)
1587  ResByArg = &Res->ResByArg[CSByConstantArg.first];
1588 
1589  if (tryUniformRetValOpt(TargetsForSlot, CSByConstantArg.second, ResByArg))
1590  continue;
1591 
1592  if (tryUniqueRetValOpt(BitWidth, TargetsForSlot, CSByConstantArg.second,
1593  ResByArg, Slot, CSByConstantArg.first))
1594  continue;
1595 
1596  // Find an allocation offset in bits in all vtables associated with the
1597  // type.
1598  uint64_t AllocBefore =
1599  findLowestOffset(TargetsForSlot, /*IsAfter=*/false, BitWidth);
1600  uint64_t AllocAfter =
1601  findLowestOffset(TargetsForSlot, /*IsAfter=*/true, BitWidth);
1602 
1603  // Calculate the total amount of padding needed to store a value at both
1604  // ends of the object.
1605  uint64_t TotalPaddingBefore = 0, TotalPaddingAfter = 0;
1606  for (auto &&Target : TargetsForSlot) {
1607  TotalPaddingBefore += std::max<int64_t>(
1608  (AllocBefore + 7) / 8 - Target.allocatedBeforeBytes() - 1, 0);
1609  TotalPaddingAfter += std::max<int64_t>(
1610  (AllocAfter + 7) / 8 - Target.allocatedAfterBytes() - 1, 0);
1611  }
1612 
1613  // If the amount of padding is too large, give up.
1614  // FIXME: do something smarter here.
1615  if (std::min(TotalPaddingBefore, TotalPaddingAfter) > 128)
1616  continue;
1617 
1618  // Calculate the offset to the value as a (possibly negative) byte offset
1619  // and (if applicable) a bit offset, and store the values in the targets.
1620  int64_t OffsetByte;
1621  uint64_t OffsetBit;
1622  if (TotalPaddingBefore <= TotalPaddingAfter)
1623  setBeforeReturnValues(TargetsForSlot, AllocBefore, BitWidth, OffsetByte,
1624  OffsetBit);
1625  else
1626  setAfterReturnValues(TargetsForSlot, AllocAfter, BitWidth, OffsetByte,
1627  OffsetBit);
1628 
1629  if (RemarksEnabled)
1630  for (auto &&Target : TargetsForSlot)
1631  Target.WasDevirt = true;
1632 
1633 
1634  if (CSByConstantArg.second.isExported()) {
1636  exportConstant(Slot, CSByConstantArg.first, "byte", OffsetByte,
1637  ResByArg->Byte);
1638  exportConstant(Slot, CSByConstantArg.first, "bit", 1ULL << OffsetBit,
1639  ResByArg->Bit);
1640  }
1641 
1642  // Rewrite each call to a load from OffsetByte/OffsetBit.
1643  Constant *ByteConst = ConstantInt::get(Int32Ty, OffsetByte);
1644  Constant *BitConst = ConstantInt::get(Int8Ty, 1ULL << OffsetBit);
1645  applyVirtualConstProp(CSByConstantArg.second,
1646  TargetsForSlot[0].Fn->getName(), ByteConst, BitConst);
1647  }
1648  return true;
1649 }
1650 
1651 void DevirtModule::rebuildGlobal(VTableBits &B) {
1652  if (B.Before.Bytes.empty() && B.After.Bytes.empty())
1653  return;
1654 
1655  // Align the before byte array to the global's minimum alignment so that we
1656  // don't break any alignment requirements on the global.
1657  Align Alignment = M.getDataLayout().getValueOrABITypeAlignment(
1658  B.GV->getAlign(), B.GV->getValueType());
1659  B.Before.Bytes.resize(alignTo(B.Before.Bytes.size(), Alignment));
1660 
1661  // Before was stored in reverse order; flip it now.
1662  for (size_t I = 0, Size = B.Before.Bytes.size(); I != Size / 2; ++I)
1663  std::swap(B.Before.Bytes[I], B.Before.Bytes[Size - 1 - I]);
1664 
1665  // Build an anonymous global containing the before bytes, followed by the
1666  // original initializer, followed by the after bytes.
1667  auto NewInit = ConstantStruct::getAnon(
1668  {ConstantDataArray::get(M.getContext(), B.Before.Bytes),
1669  B.GV->getInitializer(),
1670  ConstantDataArray::get(M.getContext(), B.After.Bytes)});
1671  auto NewGV =
1672  new GlobalVariable(M, NewInit->getType(), B.GV->isConstant(),
1673  GlobalVariable::PrivateLinkage, NewInit, "", B.GV);
1674  NewGV->setSection(B.GV->getSection());
1675  NewGV->setComdat(B.GV->getComdat());
1676  NewGV->setAlignment(MaybeAlign(B.GV->getAlignment()));
1677 
1678  // Copy the original vtable's metadata to the anonymous global, adjusting
1679  // offsets as required.
1680  NewGV->copyMetadata(B.GV, B.Before.Bytes.size());
1681 
1682  // Build an alias named after the original global, pointing at the second
1683  // element (the original initializer).
1684  auto Alias = GlobalAlias::create(
1685  B.GV->getInitializer()->getType(), 0, B.GV->getLinkage(), "",
1687  NewInit->getType(), NewGV,
1689  ConstantInt::get(Int32Ty, 1)}),
1690  &M);
1691  Alias->setVisibility(B.GV->getVisibility());
1692  Alias->takeName(B.GV);
1693 
1694  B.GV->replaceAllUsesWith(Alias);
1695  B.GV->eraseFromParent();
1696 }
1697 
1698 bool DevirtModule::areRemarksEnabled() {
1699  const auto &FL = M.getFunctionList();
1700  for (const Function &Fn : FL) {
1701  const auto &BBL = Fn.getBasicBlockList();
1702  if (BBL.empty())
1703  continue;
1704  auto DI = OptimizationRemark(DEBUG_TYPE, "", DebugLoc(), &BBL.front());
1705  return DI.isEnabled();
1706  }
1707  return false;
1708 }
1709 
1710 void DevirtModule::scanTypeTestUsers(
1711  Function *TypeTestFunc,
1712  DenseMap<Metadata *, std::set<TypeMemberInfo>> &TypeIdMap) {
1713  // Find all virtual calls via a virtual table pointer %p under an assumption
1714  // of the form llvm.assume(llvm.type.test(%p, %md)). This indicates that %p
1715  // points to a member of the type identifier %md. Group calls by (type ID,
1716  // offset) pair (effectively the identity of the virtual function) and store
1717  // to CallSlots.
1718  for (auto I = TypeTestFunc->use_begin(), E = TypeTestFunc->use_end();
1719  I != E;) {
1720  auto CI = dyn_cast<CallInst>(I->getUser());
1721  ++I;
1722  if (!CI)
1723  continue;
1724 
1725  // Search for virtual calls based on %p and add them to DevirtCalls.
1726  SmallVector<DevirtCallSite, 1> DevirtCalls;
1728  auto &DT = LookupDomTree(*CI->getFunction());
1729  findDevirtualizableCallsForTypeTest(DevirtCalls, Assumes, CI, DT);
1730 
1731  Metadata *TypeId =
1732  cast<MetadataAsValue>(CI->getArgOperand(1))->getMetadata();
1733  // If we found any, add them to CallSlots.
1734  if (!Assumes.empty()) {
1735  Value *Ptr = CI->getArgOperand(0)->stripPointerCasts();
1736  for (DevirtCallSite Call : DevirtCalls)
1737  CallSlots[{TypeId, Call.Offset}].addCallSite(Ptr, Call.CB, nullptr);
1738  }
1739 
1740  auto RemoveTypeTestAssumes = [&]() {
1741  // We no longer need the assumes or the type test.
1742  for (auto Assume : Assumes)
1743  Assume->eraseFromParent();
1744  // We can't use RecursivelyDeleteTriviallyDeadInstructions here because we
1745  // may use the vtable argument later.
1746  if (CI->use_empty())
1747  CI->eraseFromParent();
1748  };
1749 
1750  // At this point we could remove all type test assume sequences, as they
1751  // were originally inserted for WPD. However, we can keep these in the
1752  // code stream for later analysis (e.g. to help drive more efficient ICP
1753  // sequences). They will eventually be removed by a second LowerTypeTests
1754  // invocation that cleans them up. In order to do this correctly, the first
1755  // LowerTypeTests invocation needs to know that they have "Unknown" type
1756  // test resolution, so that they aren't treated as Unsat and lowered to
1757  // False, which will break any uses on assumes. Below we remove any type
1758  // test assumes that will not be treated as Unknown by LTT.
1759 
1760  // The type test assumes will be treated by LTT as Unsat if the type id is
1761  // not used on a global (in which case it has no entry in the TypeIdMap).
1762  if (!TypeIdMap.count(TypeId))
1763  RemoveTypeTestAssumes();
1764 
1765  // For ThinLTO importing, we need to remove the type test assumes if this is
1766  // an MDString type id without a corresponding TypeIdSummary. Any
1767  // non-MDString type ids are ignored and treated as Unknown by LTT, so their
1768  // type test assumes can be kept. If the MDString type id is missing a
1769  // TypeIdSummary (e.g. because there was no use on a vcall, preventing the
1770  // exporting phase of WPD from analyzing it), then it would be treated as
1771  // Unsat by LTT and we need to remove its type test assumes here. If not
1772  // used on a vcall we don't need them for later optimization use in any
1773  // case.
1774  else if (ImportSummary && isa<MDString>(TypeId)) {
1775  const TypeIdSummary *TidSummary =
1776  ImportSummary->getTypeIdSummary(cast<MDString>(TypeId)->getString());
1777  if (!TidSummary)
1778  RemoveTypeTestAssumes();
1779  else
1780  // If one was created it should not be Unsat, because if we reached here
1781  // the type id was used on a global.
1783  }
1784  }
1785 }
1786 
1787 void DevirtModule::scanTypeCheckedLoadUsers(Function *TypeCheckedLoadFunc) {
1788  Function *TypeTestFunc = Intrinsic::getDeclaration(&M, Intrinsic::type_test);
1789 
1790  for (auto I = TypeCheckedLoadFunc->use_begin(),
1791  E = TypeCheckedLoadFunc->use_end();
1792  I != E;) {
1793  auto CI = dyn_cast<CallInst>(I->getUser());
1794  ++I;
1795  if (!CI)
1796  continue;
1797 
1798  Value *Ptr = CI->getArgOperand(0);
1799  Value *Offset = CI->getArgOperand(1);
1800  Value *TypeIdValue = CI->getArgOperand(2);
1801  Metadata *TypeId = cast<MetadataAsValue>(TypeIdValue)->getMetadata();
1802 
1803  SmallVector<DevirtCallSite, 1> DevirtCalls;
1804  SmallVector<Instruction *, 1> LoadedPtrs;
1806  bool HasNonCallUses = false;
1807  auto &DT = LookupDomTree(*CI->getFunction());
1808  findDevirtualizableCallsForTypeCheckedLoad(DevirtCalls, LoadedPtrs, Preds,
1809  HasNonCallUses, CI, DT);
1810 
1811  // Start by generating "pessimistic" code that explicitly loads the function
1812  // pointer from the vtable and performs the type check. If possible, we will
1813  // eliminate the load and the type check later.
1814 
1815  // If possible, only generate the load at the point where it is used.
1816  // This helps avoid unnecessary spills.
1817  IRBuilder<> LoadB(
1818  (LoadedPtrs.size() == 1 && !HasNonCallUses) ? LoadedPtrs[0] : CI);
1819  Value *GEP = LoadB.CreateGEP(Int8Ty, Ptr, Offset);
1820  Value *GEPPtr = LoadB.CreateBitCast(GEP, PointerType::getUnqual(Int8PtrTy));
1821  Value *LoadedValue = LoadB.CreateLoad(Int8PtrTy, GEPPtr);
1822 
1823  for (Instruction *LoadedPtr : LoadedPtrs) {
1824  LoadedPtr->replaceAllUsesWith(LoadedValue);
1825  LoadedPtr->eraseFromParent();
1826  }
1827 
1828  // Likewise for the type test.
1829  IRBuilder<> CallB((Preds.size() == 1 && !HasNonCallUses) ? Preds[0] : CI);
1830  CallInst *TypeTestCall = CallB.CreateCall(TypeTestFunc, {Ptr, TypeIdValue});
1831 
1832  for (Instruction *Pred : Preds) {
1833  Pred->replaceAllUsesWith(TypeTestCall);
1834  Pred->eraseFromParent();
1835  }
1836 
1837  // We have already erased any extractvalue instructions that refer to the
1838  // intrinsic call, but the intrinsic may have other non-extractvalue uses
1839  // (although this is unlikely). In that case, explicitly build a pair and
1840  // RAUW it.
1841  if (!CI->use_empty()) {
1842  Value *Pair = UndefValue::get(CI->getType());
1843  IRBuilder<> B(CI);
1844  Pair = B.CreateInsertValue(Pair, LoadedValue, {0});
1845  Pair = B.CreateInsertValue(Pair, TypeTestCall, {1});
1846  CI->replaceAllUsesWith(Pair);
1847  }
1848 
1849  // The number of unsafe uses is initially the number of uses.
1850  auto &NumUnsafeUses = NumUnsafeUsesForTypeTest[TypeTestCall];
1851  NumUnsafeUses = DevirtCalls.size();
1852 
1853  // If the function pointer has a non-call user, we cannot eliminate the type
1854  // check, as one of those users may eventually call the pointer. Increment
1855  // the unsafe use count to make sure it cannot reach zero.
1856  if (HasNonCallUses)
1857  ++NumUnsafeUses;
1858  for (DevirtCallSite Call : DevirtCalls) {
1859  CallSlots[{TypeId, Call.Offset}].addCallSite(Ptr, Call.CB,
1860  &NumUnsafeUses);
1861  }
1862 
1863  CI->eraseFromParent();
1864  }
1865 }
1866 
1867 void DevirtModule::importResolution(VTableSlot Slot, VTableSlotInfo &SlotInfo) {
1868  auto *TypeId = dyn_cast<MDString>(Slot.TypeID);
1869  if (!TypeId)
1870  return;
1871  const TypeIdSummary *TidSummary =
1872  ImportSummary->getTypeIdSummary(TypeId->getString());
1873  if (!TidSummary)
1874  return;
1875  auto ResI = TidSummary->WPDRes.find(Slot.ByteOffset);
1876  if (ResI == TidSummary->WPDRes.end())
1877  return;
1878  const WholeProgramDevirtResolution &Res = ResI->second;
1879 
1881  assert(!Res.SingleImplName.empty());
1882  // The type of the function in the declaration is irrelevant because every
1883  // call site will cast it to the correct type.
1884  Constant *SingleImpl =
1885  cast<Constant>(M.getOrInsertFunction(Res.SingleImplName,
1886  Type::getVoidTy(M.getContext()))
1887  .getCallee());
1888 
1889  // This is the import phase so we should not be exporting anything.
1890  bool IsExported = false;
1891  applySingleImplDevirt(SlotInfo, SingleImpl, IsExported);
1892  assert(!IsExported);
1893  }
1894 
1895  for (auto &CSByConstantArg : SlotInfo.ConstCSInfo) {
1896  auto I = Res.ResByArg.find(CSByConstantArg.first);
1897  if (I == Res.ResByArg.end())
1898  continue;
1899  auto &ResByArg = I->second;
1900  // FIXME: We should figure out what to do about the "function name" argument
1901  // to the apply* functions, as the function names are unavailable during the
1902  // importing phase. For now we just pass the empty string. This does not
1903  // impact correctness because the function names are just used for remarks.
1904  switch (ResByArg.TheKind) {
1906  applyUniformRetValOpt(CSByConstantArg.second, "", ResByArg.Info);
1907  break;
1909  Constant *UniqueMemberAddr =
1910  importGlobal(Slot, CSByConstantArg.first, "unique_member");
1911  applyUniqueRetValOpt(CSByConstantArg.second, "", ResByArg.Info,
1912  UniqueMemberAddr);
1913  break;
1914  }
1916  Constant *Byte = importConstant(Slot, CSByConstantArg.first, "byte",
1917  Int32Ty, ResByArg.Byte);
1918  Constant *Bit = importConstant(Slot, CSByConstantArg.first, "bit", Int8Ty,
1919  ResByArg.Bit);
1920  applyVirtualConstProp(CSByConstantArg.second, "", Byte, Bit);
1921  break;
1922  }
1923  default:
1924  break;
1925  }
1926  }
1927 
1929  // The type of the function is irrelevant, because it's bitcast at calls
1930  // anyhow.
1931  Constant *JT = cast<Constant>(
1932  M.getOrInsertFunction(getGlobalName(Slot, {}, "branch_funnel"),
1933  Type::getVoidTy(M.getContext()))
1934  .getCallee());
1935  bool IsExported = false;
1936  applyICallBranchFunnel(SlotInfo, JT, IsExported);
1937  assert(!IsExported);
1938  }
1939 }
1940 
1941 void DevirtModule::removeRedundantTypeTests() {
1942  auto True = ConstantInt::getTrue(M.getContext());
1943  for (auto &&U : NumUnsafeUsesForTypeTest) {
1944  if (U.second == 0) {
1945  U.first->replaceAllUsesWith(True);
1946  U.first->eraseFromParent();
1947  }
1948  }
1949 }
1950 
1951 bool DevirtModule::run() {
1952  // If only some of the modules were split, we cannot correctly perform
1953  // this transformation. We already checked for the presense of type tests
1954  // with partially split modules during the thin link, and would have emitted
1955  // an error if any were found, so here we can simply return.
1956  if ((ExportSummary && ExportSummary->partiallySplitLTOUnits()) ||
1957  (ImportSummary && ImportSummary->partiallySplitLTOUnits()))
1958  return false;
1959 
1960  Function *TypeTestFunc =
1961  M.getFunction(Intrinsic::getName(Intrinsic::type_test));
1962  Function *TypeCheckedLoadFunc =
1963  M.getFunction(Intrinsic::getName(Intrinsic::type_checked_load));
1964  Function *AssumeFunc = M.getFunction(Intrinsic::getName(Intrinsic::assume));
1965 
1966  // Normally if there are no users of the devirtualization intrinsics in the
1967  // module, this pass has nothing to do. But if we are exporting, we also need
1968  // to handle any users that appear only in the function summaries.
1969  if (!ExportSummary &&
1970  (!TypeTestFunc || TypeTestFunc->use_empty() || !AssumeFunc ||
1971  AssumeFunc->use_empty()) &&
1972  (!TypeCheckedLoadFunc || TypeCheckedLoadFunc->use_empty()))
1973  return false;
1974 
1975  // Rebuild type metadata into a map for easy lookup.
1976  std::vector<VTableBits> Bits;
1978  buildTypeIdentifierMap(Bits, TypeIdMap);
1979 
1980  if (TypeTestFunc && AssumeFunc)
1981  scanTypeTestUsers(TypeTestFunc, TypeIdMap);
1982 
1983  if (TypeCheckedLoadFunc)
1984  scanTypeCheckedLoadUsers(TypeCheckedLoadFunc);
1985 
1986  if (ImportSummary) {
1987  for (auto &S : CallSlots)
1988  importResolution(S.first, S.second);
1989 
1990  removeRedundantTypeTests();
1991 
1992  // We have lowered or deleted the type instrinsics, so we will no
1993  // longer have enough information to reason about the liveness of virtual
1994  // function pointers in GlobalDCE.
1995  for (GlobalVariable &GV : M.globals())
1996  GV.eraseMetadata(LLVMContext::MD_vcall_visibility);
1997 
1998  // The rest of the code is only necessary when exporting or during regular
1999  // LTO, so we are done.
2000  return true;
2001  }
2002 
2003  if (TypeIdMap.empty())
2004  return true;
2005 
2006  // Collect information from summary about which calls to try to devirtualize.
2007  if (ExportSummary) {
2009  for (auto &P : TypeIdMap) {
2010  if (auto *TypeId = dyn_cast<MDString>(P.first))
2011  MetadataByGUID[GlobalValue::getGUID(TypeId->getString())].push_back(
2012  TypeId);
2013  }
2014 
2015  for (auto &P : *ExportSummary) {
2016  for (auto &S : P.second.SummaryList) {
2017  auto *FS = dyn_cast<FunctionSummary>(S.get());
2018  if (!FS)
2019  continue;
2020  // FIXME: Only add live functions.
2021  for (FunctionSummary::VFuncId VF : FS->type_test_assume_vcalls()) {
2022  for (Metadata *MD : MetadataByGUID[VF.GUID]) {
2023  CallSlots[{MD, VF.Offset}].CSInfo.addSummaryTypeTestAssumeUser(FS);
2024  }
2025  }
2026  for (FunctionSummary::VFuncId VF : FS->type_checked_load_vcalls()) {
2027  for (Metadata *MD : MetadataByGUID[VF.GUID]) {
2028  CallSlots[{MD, VF.Offset}].CSInfo.addSummaryTypeCheckedLoadUser(FS);
2029  }
2030  }
2031  for (const FunctionSummary::ConstVCall &VC :
2032  FS->type_test_assume_const_vcalls()) {
2033  for (Metadata *MD : MetadataByGUID[VC.VFunc.GUID]) {
2034  CallSlots[{MD, VC.VFunc.Offset}]
2035  .ConstCSInfo[VC.Args]
2036  .addSummaryTypeTestAssumeUser(FS);
2037  }
2038  }
2039  for (const FunctionSummary::ConstVCall &VC :
2040  FS->type_checked_load_const_vcalls()) {
2041  for (Metadata *MD : MetadataByGUID[VC.VFunc.GUID]) {
2042  CallSlots[{MD, VC.VFunc.Offset}]
2043  .ConstCSInfo[VC.Args]
2044  .addSummaryTypeCheckedLoadUser(FS);
2045  }
2046  }
2047  }
2048  }
2049  }
2050 
2051  // For each (type, offset) pair:
2052  bool DidVirtualConstProp = false;
2053  std::map<std::string, Function*> DevirtTargets;
2054  for (auto &S : CallSlots) {
2055  // Search each of the members of the type identifier for the virtual
2056  // function implementation at offset S.first.ByteOffset, and add to
2057  // TargetsForSlot.
2058  std::vector<VirtualCallTarget> TargetsForSlot;
2059  WholeProgramDevirtResolution *Res = nullptr;
2060  const std::set<TypeMemberInfo> &TypeMemberInfos = TypeIdMap[S.first.TypeID];
2061  if (ExportSummary && isa<MDString>(S.first.TypeID) &&
2062  TypeMemberInfos.size())
2063  // For any type id used on a global's type metadata, create the type id
2064  // summary resolution regardless of whether we can devirtualize, so that
2065  // lower type tests knows the type id is not Unsat. If it was not used on
2066  // a global's type metadata, the TypeIdMap entry set will be empty, and
2067  // we don't want to create an entry (with the default Unknown type
2068  // resolution), which can prevent detection of the Unsat.
2069  Res = &ExportSummary
2070  ->getOrInsertTypeIdSummary(
2071  cast<MDString>(S.first.TypeID)->getString())
2072  .WPDRes[S.first.ByteOffset];
2073  if (tryFindVirtualCallTargets(TargetsForSlot, TypeMemberInfos,
2074  S.first.ByteOffset)) {
2075 
2076  if (!trySingleImplDevirt(ExportSummary, TargetsForSlot, S.second, Res)) {
2077  DidVirtualConstProp |=
2078  tryVirtualConstProp(TargetsForSlot, S.second, Res, S.first);
2079 
2080  tryICallBranchFunnel(TargetsForSlot, S.second, Res, S.first);
2081  }
2082 
2083  // Collect functions devirtualized at least for one call site for stats.
2084  if (RemarksEnabled)
2085  for (const auto &T : TargetsForSlot)
2086  if (T.WasDevirt)
2087  DevirtTargets[std::string(T.Fn->getName())] = T.Fn;
2088  }
2089 
2090  // CFI-specific: if we are exporting and any llvm.type.checked.load
2091  // intrinsics were *not* devirtualized, we need to add the resulting
2092  // llvm.type.test intrinsics to the function summaries so that the
2093  // LowerTypeTests pass will export them.
2094  if (ExportSummary && isa<MDString>(S.first.TypeID)) {
2095  auto GUID =
2096  GlobalValue::getGUID(cast<MDString>(S.first.TypeID)->getString());
2097  for (auto FS : S.second.CSInfo.SummaryTypeCheckedLoadUsers)
2098  FS->addTypeTest(GUID);
2099  for (auto &CCS : S.second.ConstCSInfo)
2100  for (auto FS : CCS.second.SummaryTypeCheckedLoadUsers)
2101  FS->addTypeTest(GUID);
2102  }
2103  }
2104 
2105  if (RemarksEnabled) {
2106  // Generate remarks for each devirtualized function.
2107  for (const auto &DT : DevirtTargets) {
2108  Function *F = DT.second;
2109 
2110  using namespace ore;
2111  OREGetter(F).emit(OptimizationRemark(DEBUG_TYPE, "Devirtualized", F)
2112  << "devirtualized "
2113  << NV("FunctionName", DT.first));
2114  }
2115  }
2116 
2117  removeRedundantTypeTests();
2118 
2119  // Rebuild each global we touched as part of virtual constant propagation to
2120  // include the before and after bytes.
2121  if (DidVirtualConstProp)
2122  for (VTableBits &B : Bits)
2123  rebuildGlobal(B);
2124 
2125  // We have lowered or deleted the type instrinsics, so we will no
2126  // longer have enough information to reason about the liveness of virtual
2127  // function pointers in GlobalDCE.
2128  for (GlobalVariable &GV : M.globals())
2129  GV.eraseMetadata(LLVMContext::MD_vcall_visibility);
2130 
2131  return true;
2132 }
2133 
2134 void DevirtIndex::run() {
2135  if (ExportSummary.typeIdCompatibleVtableMap().empty())
2136  return;
2137 
2139  for (auto &P : ExportSummary.typeIdCompatibleVtableMap()) {
2140  NameByGUID[GlobalValue::getGUID(P.first)].push_back(P.first);
2141  }
2142 
2143  // Collect information from summary about which calls to try to devirtualize.
2144  for (auto &P : ExportSummary) {
2145  for (auto &S : P.second.SummaryList) {
2146  auto *FS = dyn_cast<FunctionSummary>(S.get());
2147  if (!FS)
2148  continue;
2149  // FIXME: Only add live functions.
2150  for (FunctionSummary::VFuncId VF : FS->type_test_assume_vcalls()) {
2151  for (StringRef Name : NameByGUID[VF.GUID]) {
2152  CallSlots[{Name, VF.Offset}].CSInfo.addSummaryTypeTestAssumeUser(FS);
2153  }
2154  }
2155  for (FunctionSummary::VFuncId VF : FS->type_checked_load_vcalls()) {
2156  for (StringRef Name : NameByGUID[VF.GUID]) {
2157  CallSlots[{Name, VF.Offset}].CSInfo.addSummaryTypeCheckedLoadUser(FS);
2158  }
2159  }
2160  for (const FunctionSummary::ConstVCall &VC :
2161  FS->type_test_assume_const_vcalls()) {
2162  for (StringRef Name : NameByGUID[VC.VFunc.GUID]) {
2163  CallSlots[{Name, VC.VFunc.Offset}]
2164  .ConstCSInfo[VC.Args]
2165  .addSummaryTypeTestAssumeUser(FS);
2166  }
2167  }
2168  for (const FunctionSummary::ConstVCall &VC :
2169  FS->type_checked_load_const_vcalls()) {
2170  for (StringRef Name : NameByGUID[VC.VFunc.GUID]) {
2171  CallSlots[{Name, VC.VFunc.Offset}]
2172  .ConstCSInfo[VC.Args]
2173  .addSummaryTypeCheckedLoadUser(FS);
2174  }
2175  }
2176  }
2177  }
2178 
2179  std::set<ValueInfo> DevirtTargets;
2180  // For each (type, offset) pair:
2181  for (auto &S : CallSlots) {
2182  // Search each of the members of the type identifier for the virtual
2183  // function implementation at offset S.first.ByteOffset, and add to
2184  // TargetsForSlot.
2185  std::vector<ValueInfo> TargetsForSlot;
2186  auto TidSummary = ExportSummary.getTypeIdCompatibleVtableSummary(S.first.TypeID);
2187  assert(TidSummary);
2188  // Create the type id summary resolution regardlness of whether we can
2189  // devirtualize, so that lower type tests knows the type id is used on
2190  // a global and not Unsat.
2192  &ExportSummary.getOrInsertTypeIdSummary(S.first.TypeID)
2193  .WPDRes[S.first.ByteOffset];
2194  if (tryFindVirtualCallTargets(TargetsForSlot, *TidSummary,
2195  S.first.ByteOffset)) {
2196 
2197  if (!trySingleImplDevirt(TargetsForSlot, S.first, S.second, Res,
2198  DevirtTargets))
2199  continue;
2200  }
2201  }
2202 
2203  // Optionally have the thin link print message for each devirtualized
2204  // function.
2205  if (PrintSummaryDevirt)
2206  for (const auto &DT : DevirtTargets)
2207  errs() << "Devirtualized call to " << DT << "\n";
2208 
2209  return;
2210 }
void setVisibility(VisibilityTypes V)
Definition: GlobalValue.h:235
uint64_t CallInst * C
StringRef getSection() const
Get the custom section of this global if it has one.
Definition: GlobalObject.h:115
SymbolTableList< Instruction >::iterator eraseFromParent()
This method unlinks &#39;this&#39; from the containing basic block and deletes it.
Definition: Instruction.cpp:80
unsigned getAlignment() const
FIXME: Remove this function once transition to Align is over.
Definition: GlobalObject.h:74
use_iterator use_end()
Definition: Value.h:365
static Error checkCombinedSummaryForTesting(ModuleSummaryIndex *Summary)
const std::string & getTargetTriple() const
Get the target triple which is a string describing the target host.
Definition: Module.h:249
std::vector< TypeIdOffsetVtableInfo > TypeIdCompatibleVtableInfo
List of vtable definitions decorated by a particular type identifier, and their corresponding offsets...
LLVM_NODISCARD std::enable_if_t< !is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type > dyn_cast(const Y &Val)
Definition: Casting.h:334
bool empty() const
Definition: Function.h:711
bool hasLocalLinkage() const
Definition: GlobalValue.h:445
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
DiagnosticInfoOptimizationBase::Argument NV
Whole program devirtualization
static unsigned getHashValue(const VTableSlot &I)
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:769
const Constant * getInitializer() const
getInitializer - Return the initializer for this global variable.
This class represents lattice values for constants.
Definition: AllocatorList.h:23
Value * CreateGEP(Value *Ptr, ArrayRef< Value *> IdxList, const Twine &Name="")
Definition: IRBuilder.h:1757
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:67
static Constant * getGetElementPtr(Type *Ty, Constant *C, ArrayRef< Constant *> IdxList, bool InBounds=false, Optional< unsigned > InRangeIndex=None, Type *OnlyIfReducedTy=nullptr)
Getelementptr form.
Definition: Constants.h:1166
amdgpu Simplify well known AMD library false FunctionCallee Value const Twine & Name
Function * getCaller()
Helper to get the caller (the parent function).
void findDevirtualizableCallsForTypeTest(SmallVectorImpl< DevirtCallSite > &DevirtCalls, SmallVectorImpl< CallInst *> &Assumes, const CallInst *CI, DominatorTree &DT)
Given a call to the intrinsic @llvm.type.test, find all devirtualizable call sites based on the call ...
static CallInst * Create(FunctionType *Ty, Value *F, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Global variable summary information to aid decisions and implementation of importing.
VirtualCallTarget(Function *Fn, const TypeMemberInfo *TM)
Unsatisfiable type (i.e. no global has this type metadata)
Subclass of Error for the sole purpose of identifying the success path in the type system...
Definition: Error.h:330
void push_back(const T &Elt)
Definition: SmallVector.h:246
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
GlobalObject::VCallVisibility getVCallVisibility() const
Helper for check-and-exit error handling.
Definition: Error.h:1306
void initializeWholeProgramDevirtPass(PassRegistry &)
const auto & typeIdCompatibleVtableMap() const
This class represents a function call, abstracting a target machine&#39;s calling convention.
This file contains the declarations for metadata subclasses.
An immutable pass that tracks lazily created AssumptionCache objects.
An efficient, type-erasing, non-owning reference to a callable.
Definition: STLExtras.h:176
static Constant * getIntToPtr(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:2011
uint64_t Info
Additional information for the resolution:
Like Internal, but omit from symbol table.
Definition: GlobalValue.h:56
Externally visible function.
Definition: GlobalValue.h:48
const StringMap< std::pair< uint64_t, ModuleHash > > & modulePaths() const
Table of modules, containing module hash and id.
static cl::opt< unsigned > ClThreshold("wholeprogramdevirt-branch-funnel-threshold", cl::Hidden, cl::init(10), cl::ZeroOrMore, cl::desc("Maximum number of call targets per " "call site to enable branch funnels"))
This class implements a map that also provides access to all stored values in a deterministic order...
Definition: MapVector.h:37
A debug info location.
Definition: DebugLoc.h:33
Metadata node.
Definition: Metadata.h:870
Base class for all callable instructions (InvokeInst and CallInst) Holds everything related to callin...
Definition: InstrTypes.h:1100
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:233
F(f)
User::op_iterator arg_end()
Return the iterator pointing to the end of the argument list.
Definition: InstrTypes.h:1230
const GlobalListType & getGlobalList() const
Get the Module&#39;s list of global variables (constant).
Definition: Module.h:535
static IntegerType * getInt64Ty(LLVMContext &C)
Definition: Type.cpp:187
Hexagon Common GEP
MemoryAccessKind computeFunctionBodyMemoryAccess(Function &F, AAResults &AAR)
Returns the memory access properties of this copy of the function.
const TypeIdSummary * getTypeIdSummary(StringRef TypeId) const
This returns either a pointer to the type id summary (if present in the summary map) or null (if not ...
void setAfterReturnValues(MutableArrayRef< VirtualCallTarget > Targets, uint64_t AllocAfter, unsigned BitWidth, int64_t &OffsetByte, uint64_t &OffsetBit)
std::map< uint64_t, WholeProgramDevirtResolution > WPDRes
Mapping from byte offset to whole-program devirt resolution for that (typeid, byte offset) pair...
VCallVisibility getVCallVisibility() const
Definition: Metadata.cpp:1513
static bool AddCalls(VTableSlotInfo &SlotInfo, const ValueInfo &Callee)
static Optional< bool > isBigEndian(const ArrayRef< int64_t > ByteOffsets, int64_t FirstOffset)
static bool isLocalLinkage(LinkageTypes Linkage)
Definition: GlobalValue.h:329
TypeTestResolution TTRes
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:328
Export information to summary.
const char * getName() const
getName - Get the target name.
static ReturnInst * Create(LLVMContext &C, Value *retVal=nullptr, Instruction *InsertBefore=nullptr)
void setBeforeReturnValues(MutableArrayRef< VirtualCallTarget > Targets, uint64_t AllocBefore, unsigned BitWidth, int64_t &OffsetByte, uint64_t &OffsetBit)
unsigned countTrailingZeros(T Val, ZeroBehavior ZB=ZB_Width)
Count number of 0&#39;s from the least significant bit to the most stopping at the first 1...
Definition: MathExtras.h:157
void findDevirtualizableCallsForTypeCheckedLoad(SmallVectorImpl< DevirtCallSite > &DevirtCalls, SmallVectorImpl< Instruction *> &LoadedPtrs, SmallVectorImpl< Instruction *> &Preds, bool &HasNonCallUses, const CallInst *CI, DominatorTree &DT)
Given a call to the intrinsic @llvm.type.checked.load, find all devirtualizable call sites based on t...
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
AnalysisUsage & addRequired()
StringRef getName(ID id)
Return the LLVM name for an intrinsic, such as "llvm.ppc.altivec.lvx".
Definition: Function.cpp:701
const DataLayout & getDataLayout() const
Get the data layout for the module&#39;s target platform.
Definition: Module.cpp:397
bool arg_empty() const
Definition: InstrTypes.h:1246
When retpoline mitigation is enabled, use a branch funnel that is defined in the merged module...
LLVMContext & getContext() const
Get the global data context.
Definition: Module.h:253
The returned value is undefined.
Definition: MathExtras.h:47
void updateIndexWPDForExports(ModuleSummaryIndex &Summary, function_ref< bool(StringRef, ValueInfo)> isExported, std::map< ValueInfo, std::vector< VTableSlotSummary >> &LocalWPDTargetsMap)
Call after cross-module importing to update the recorded single impl devirt target names for any loca...
bool isConstant() const
If the value is a global constant, its value is immutable throughout the runtime execution of the pro...
static bool isEqual(const VTableSlotSummary &LHS, const VTableSlotSummary &RHS)
static std::string getGlobalNameForLocal(StringRef Name, ModuleHash ModHash)
Convenience method for creating a promoted global name for the given value name of a local...
This class is a functor to be used in legacy module or SCC passes for computing AA results for a func...
static constexpr const char * getRegularLTOModuleName()
TypeID
Definitions of all of the base types for the Type system.
Definition: Type.h:55
No attributes have been set.
Definition: Attributes.h:72
AttributeSet getRetAttributes() const
The attributes for the ret value are returned.
unsigned Intr
CallInst * CreateCall(FunctionType *FTy, Value *Callee, ArrayRef< Value *> Args=None, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:2328
void setName(const Twine &Name)
Change the name of the value.
Definition: Value.cpp:342
Tagged union holding either a T or a Error.
Definition: APFloat.h:42
static bool isEqual(const VTableSlot &LHS, const VTableSlot &RHS)
enum llvm::WholeProgramDevirtResolution::Kind TheKind
Class to represent function types.
Definition: DerivedTypes.h:108
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:244
void updateVCallVisibilityInIndex(ModuleSummaryIndex &Index, bool WholeProgramVisibilityEnabledInLTO)
If whole program visibility asserted, then upgrade all public vcall visibility metadata on vtable def...
InvokeInst * CreateInvoke(FunctionType *Ty, Value *Callee, BasicBlock *NormalDest, BasicBlock *UnwindDest, ArrayRef< Value *> Args, ArrayRef< OperandBundleDef > OpBundles, const Twine &Name="")
Create an invoke instruction.
Definition: IRBuilder.h:996
Class to represent array types.
Definition: DerivedTypes.h:358
AttributeSet getParamAttributes(unsigned ArgNo) const
The attributes for the argument or parameter at the given index are returned.
bool isVarArg() const
Definition: DerivedTypes.h:128
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:32
LinkageTypes getLinkage() const
Definition: GlobalValue.h:461
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:486
constexpr char Attrs[]
Key for Kernel::Metadata::mAttrs.
unsigned getBitWidth() const
Get the number of bits in this IntegerType.
Definition: DerivedTypes.h:71
MaybeAlign getAlign() const
Returns the alignment of the given variable or function.
Definition: GlobalObject.h:83
Class to hold module path string table and global value map, and encapsulate methods for operating on...
static ConstantAsMetadata * get(Constant *C)
Definition: Metadata.h:410
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
ArrayRef< std::unique_ptr< GlobalValueSummary > > getSummaryList() const
Function * getDeclaration(Module *M, ID id, ArrayRef< Type *> Tys=None)
Create or insert an LLVM Function declaration for an intrinsic, and return it.
Definition: Function.cpp:1161
The file should be opened in text mode on platforms that make this distinction.
Definition: FileSystem.h:767
Class to represent pointers.
Definition: DerivedTypes.h:662
static PreservedAnalyses none()
Convenience factory function for the empty preserved set.
Definition: PassManager.h:157
static Constant * getBitCast(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:2025
IntegerType * getIntPtrType(LLVMContext &C, unsigned AddressSpace=0) const
Returns an integer type with size at least as big as that of a pointer in the given address space...
Definition: DataLayout.cpp:789
static MDTuple * get(LLVMContext &Context, ArrayRef< Metadata *> MDs)
Definition: Metadata.h:1172
#define P(N)
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:434
bool hasAttribute(AttrKind Val) const
Return true if the attribute is present.
Definition: Attributes.cpp:282
static Function * Create(FunctionType *Ty, LinkageTypes Linkage, unsigned AddrSpace, const Twine &N="", Module *M=nullptr)
Definition: Function.h:137
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:154
* if(!EatIfPresent(lltok::kw_thread_local)) return false
ParseOptionalThreadLocal := /*empty.
static AttributeSet get(LLVMContext &C, const AttrBuilder &B)
Definition: Attributes.cpp:648
void setVCallVisibility(GlobalObject::VCallVisibility Vis)
VisibilityTypes getVisibility() const
Definition: GlobalValue.h:229
MutableArrayRef - Represent a mutable reference to an array (0 or more elements consecutively in memo...
Definition: ArrayRef.h:298
void runWholeProgramDevirtOnIndex(ModuleSummaryIndex &Summary, std::set< GlobalValue::GUID > &ExportedGUIDs, std::map< ValueInfo, std::vector< VTableSlotSummary >> &LocalWPDTargetsMap)
Perform index-based whole program devirtualization on the Summary index.
Import information from summary.
LLVM Basic Block Representation.
Definition: BasicBlock.h:58
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
A call site that could be devirtualized.
size_t size() const
size - Get the array size.
Definition: ArrayRef.h:156
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
This is an important base class in LLVM.
Definition: Constant.h:41
Error errorCodeToError(std::error_code EC)
Helper for converting an std::error_code to a Error.
Definition: Error.cpp:87
ValuesClass values(OptsTy... Options)
Helper to build a ValuesClass by forwarding a variable number of arguments as an initializer list to ...
Definition: CommandLine.h:690
PreservedAnalyses run(Module &M, ModuleAnalysisManager &)
Value * CreateBitCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:2050
This file contains the declarations for the subclasses of Constant, which represent the different fla...
#define DEBUG_TYPE
TypeSize getTypeAllocSize(Type *Ty) const
Returns the offset in bytes between successive objects of the specified type, including alignment pad...
Definition: DataLayout.h:490
A manager for alias analyses.
FunctionType * getFunctionType() const
Definition: InstrTypes.h:1162
cl::list< std::string > SkipFunctionNames("wholeprogramdevirt-skip", cl::desc("Prevent function(s) from being devirtualized"), cl::Hidden, cl::ZeroOrMore, cl::CommaSeparated)
Provide way to prevent certain function from being devirtualized.
Class to accumulate and hold information about a callee.
Diagnostic information for applied optimization remarks.
void eraseFromParent()
eraseFromParent - This method unlinks &#39;this&#39; from the containing module and deletes it...
Definition: Globals.cpp:380
INITIALIZE_PASS_BEGIN(WholeProgramDevirt, "wholeprogramdevirt", "Whole program devirtualization", false, false) INITIALIZE_PASS_END(WholeProgramDevirt
ArrayRef< Type * > params() const
Definition: DerivedTypes.h:135
Expected< T > errorOrToExpected(ErrorOr< T > &&EO)
Convert an ErrorOr<T> to an Expected<T>.
Definition: Error.h:1142
Represent the analysis usage information of a pass.
void addAttribute(unsigned i, Attribute::AttrKind Kind)
adds the attribute to the list of attributes.
Definition: Function.cpp:440
static Type * getVoidTy(LLVMContext &C)
Definition: Type.cpp:170
Type::TypeID TypeID
Expected< ExpressionValue > min(const ExpressionValue &Lhs, const ExpressionValue &Rhs)
Definition: FileCheck.cpp:305
void setCallingConv(CallingConv::ID CC)
Definition: InstrTypes.h:1375
amdgpu Simplify well known AMD library false FunctionCallee Value * Arg
static FunctionType * get(Type *Result, ArrayRef< Type *> Params, bool isVarArg)
This static method is the primary way of constructing a FunctionType.
Definition: Type.cpp:311
static BasicBlock * Create(LLVMContext &Context, const Twine &Name="", Function *Parent=nullptr, BasicBlock *InsertBefore=nullptr)
Creates a new BasicBlock.
Definition: BasicBlock.h:100
void reserve(size_type NumEntries)
Grow the densemap so that it can contain at least NumEntries items before resizing again...
Definition: DenseMap.h:104
const ModuleHash & getModuleHash(const StringRef ModPath) const
Get the module SHA1 hash recorded for the given module path.
raw_fd_ostream & errs()
This returns a reference to a raw_ostream for standard error.
LLVM_NODISCARD bool contains(StringRef Other) const
Return true if the given string is a substring of *this, and false otherwise.
Definition: StringRef.h:465
Class to represent integer types.
Definition: DerivedTypes.h:40
constexpr unsigned BitWidth
Definition: BitmaskEnum.h:147
enum llvm::WholeProgramDevirtResolution::ByArg::Kind TheKind
static GUID getGUID(StringRef GlobalName)
Return a 64-bit global unique ID constructed from global value name (i.e.
Definition: GlobalValue.h:507
LoadInst * CreateLoad(Type *Ty, Value *Ptr, const char *Name)
Provided to resolve &#39;CreateLoad(Ty, Ptr, "...")&#39; correctly, instead of converting the string to &#39;bool...
Definition: IRBuilder.h:1606
static UndefValue * get(Type *T)
Static factory methods - Return an &#39;undef&#39; object of the specified type.
Definition: Constants.cpp:1665
const Constant * stripPointerCasts() const
Definition: Constant.h:191
Comdat * getOrInsertComdat(StringRef Name)
Return the Comdat in the module with the specified name.
Definition: Module.cpp:526
const Value * stripPointerCasts() const
Strip off pointer casts, all-zero GEPs and address space casts.
Definition: Value.cpp:593
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:160
void consumeError(Error Err)
Consume a Error without doing anything.
Definition: Error.h:1006
static PointerType * getInt8PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:234
bool isEnabled() const override
std::string & str()
Flushes the stream contents to the target string and returns the string&#39;s reference.
Definition: raw_ostream.h:539
INITIALIZE_PASS_END(RegBankSelect, DEBUG_TYPE, "Assign register bank of generic virtual registers", false, false) RegBankSelect
Value * CreateICmp(CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2274
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:39
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:45
An "identifier" for a virtual function.
Struct that holds a reference to a particular GUID in a global value summary.
This class evaluates LLVM IR, producing the Constant representing each SSA instruction.
Definition: Evaluator.h:38
Value * CreateZExt(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1958
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
static PointerType * getUnqual(Type *ElementType)
This constructs a pointer to an object of the specified type in the generic address space (address sp...
Definition: DerivedTypes.h:677
This is the shared class of boolean and integer constants.
Definition: Constants.h:77
void setSelectionKind(SelectionKind Val)
Definition: Comdat.h:45
Align max(MaybeAlign Lhs, Align Rhs)
Definition: Alignment.h:350
This struct is a compact representation of a valid (power of two) or undefined (0) alignment...
Definition: Alignment.h:119
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:883
Module.h This file contains the declarations for the Module class.
Single implementation devirtualization.
static bool isAvailableExternallyLinkage(LinkageTypes Linkage)
Definition: GlobalValue.h:302
Type * getReturnType() const
Definition: DerivedTypes.h:129
static Expected< GlobPattern > create(StringRef Pat)
unsigned getProgramAddressSpace() const
Definition: DataLayout.h:287
static Constant * get(Type *Ty, uint64_t V, bool isSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:786
static BranchInst * Create(BasicBlock *IfTrue, Instruction *InsertBefore=nullptr)
ArrayRef< VirtFuncOffset > vTableFuncs() const
AttributeList getAttributes() const
Return the parameter attributes for this call.
Definition: InstrTypes.h:1390
static ConstantInt * getTrue(LLVMContext &Context)
Definition: Constants.cpp:742
void setLinkage(LinkageTypes LT)
Definition: GlobalValue.h:454
enum llvm::TypeTestResolution::Kind TheKind
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:962
wholeprogramdevirt
Target - Wrapper for Target specific information.
unsigned getNumAttrSets() const
A specification for a virtual function call with all constant integer arguments.
void WriteIndexToFile(const ModuleSummaryIndex &Index, raw_ostream &Out, const std::map< std::string, GVSummaryMapTy > *ModuleToSummariesForIndex=nullptr)
Write the specified module summary index to the given raw output stream, where it will be written in ...
cl::opt< bool > WholeProgramVisibility("whole-program-visibility", cl::init(false), cl::Hidden, cl::ZeroOrMore, cl::desc("Enable whole program visibility"))
Provide a way to force enable whole program visibility in tests.
GUID getGUID() const
Return a 64-bit global unique ID constructed from global value name (i.e.
Definition: GlobalValue.h:511
ArrayRef< T > slice(size_t N, size_t M) const
slice(n, m) - Chop off the first N elements of the array, and keep M elements in the array...
Definition: ArrayRef.h:186
ValueInfo getValueInfo(const GlobalValueSummaryMapTy::value_type &R) const
Return a ValueInfo for the index value_type (convenient when iterating index).
#define clEnumValN(ENUMVAL, FLAGNAME, DESC)
Definition: CommandLine.h:665
const Comdat * getComdat() const
Definition: GlobalObject.h:126
ModulePass * createWholeProgramDevirtPass(ModuleSummaryIndex *ExportSummary, const ModuleSummaryIndex *ImportSummary)
This pass implements whole-program devirtualization using type metadata.
User::op_iterator arg_begin()
Return the iterator pointing to the beginning of the argument list.
Definition: InstrTypes.h:1224
use_iterator use_begin()
Definition: Value.h:357
static bool hasWholeProgramVisibility(bool WholeProgramVisibilityEnabledInLTO)
uint64_t alignTo(uint64_t Size, Align A)
Returns a multiple of A needed to store Size bytes.
Definition: Alignment.h:158
const DebugLoc & getDebugLoc() const
Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:363
std::map< std::vector< uint64_t >, ByArg > ResByArg
Resolutions for calls with all constant integer arguments (excluding the first argument, "this"), where the key is the argument vector.
Constant * getOrInsertGlobal(StringRef Name, Type *Ty, function_ref< GlobalVariable *()> CreateGlobalCallback)
Look up the specified global in the module symbol table.
Definition: Module.cpp:204
static cl::opt< std::string > ClWriteSummary("wholeprogramdevirt-write-summary", cl::desc("Write summary to given bitcode or YAML file after running pass. " "Output file format is deduced from extension: *.bc means writing " "bitcode, otherwise YAML"), cl::Hidden)
A raw_ostream that writes to a file descriptor.
Definition: raw_ostream.h:408
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:186
uint64_t findLowestOffset(ArrayRef< VirtualCallTarget > Targets, bool IsAfter, uint64_t Size)
StringRef getValueAsString() const
Return the attribute&#39;s value as a string.
Definition: Attributes.cpp:267
CallingConv::ID getCallingConv() const
Definition: InstrTypes.h:1371
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:270
static Constant * getPtrToInt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1997
#define I(x, y, z)
Definition: MD5.cpp:59
ModulePass class - This class is used to implement unstructured interprocedural optimizations and ana...
Definition: Pass.h:224
static ArrayType * get(Type *ElementType, uint64_t NumElements)
This static method is the primary way to construct an ArrayType.
Definition: Type.cpp:571
void setAttributes(AttributeList A)
Set the parameter attributes for this call.
Definition: InstrTypes.h:1394
Type * getValueType() const
Definition: GlobalValue.h:273
const BasicBlockListType & getBasicBlockList() const
Get the underlying elements of the Function...
Definition: Function.h:682
uint32_t Size
Definition: Profile.cpp:46
Rename collisions when linking (static functions).
Definition: GlobalValue.h:55
static Attribute get(LLVMContext &Context, AttrKind Kind, uint64_t Val=0)
Return a uniquified Attribute object.
Definition: Attributes.cpp:81
Provides passes for computing function attributes based on interprocedural analyses.
Function summary information to aid decisions and implementation of importing.
static ErrorOr< std::unique_ptr< MemoryBuffer > > getFile(const Twine &Filename, int64_t FileSize=-1, bool RequiresNullTerminator=true, bool IsVolatile=false)
Open the specified file as a MemoryBuffer, returning a new MemoryBuffer if successful, otherwise returning null.
static cl::opt< bool > PrintSummaryDevirt("wholeprogramdevirt-print-index-based", cl::Hidden, cl::init(false), cl::ZeroOrMore, cl::desc("Print index-based devirtualization messages"))
static cl::opt< PassSummaryAction > ClSummaryAction("wholeprogramdevirt-summary-action", cl::desc("What to do with the summary when running this pass"), cl::values(clEnumValN(PassSummaryAction::None, "none", "Do nothing"), clEnumValN(PassSummaryAction::Import, "import", "Import typeid resolutions from summary and globals"), clEnumValN(PassSummaryAction::Export, "export", "Export typeid resolutions to summary and globals")), cl::Hidden)
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
A raw_ostream that writes to an std::string.
Definition: raw_ostream.h:521
aarch64 promote const
LLVM Value Representation.
Definition: Value.h:74
Expected< std::unique_ptr< ModuleSummaryIndex > > getModuleSummaryIndex(MemoryBufferRef Buffer)
Parse the specified bitcode buffer, returning the module summary index.
Lightweight error class with error context and mandatory checking.
Definition: Error.h:157
static const Function * getParent(const Value *V)
AttributeSet getFnAttributes() const
The function attributes are returned.
Attribute getFnAttribute(Attribute::AttrKind Kind) const
Return the attribute for the given attribute kind.
Definition: Function.h:340
static Constant * getAnon(ArrayRef< Constant *> V, bool Packed=false)
Return an anonymous struct that has the specified elements.
Definition: Constants.h:476
cl::opt< bool > DisableWholeProgramVisibility("disable-whole-program-visibility", cl::init(false), cl::Hidden, cl::ZeroOrMore, cl::desc("Disable whole program visibility (overrides enabling options)"))
Provide a way to force disable whole program for debugging or workarounds, when enabled via the linke...
static Constant * get(LLVMContext &Context, ArrayRef< ElementTy > Elts)
get() constructor - Return a constant with array type with an element count and element type matching...
Definition: Constants.h:706
iterator_range< global_iterator > globals()
Definition: Module.h:599
iterator_range< global_object_iterator > global_objects()
Definition: Module.cpp:412
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:57
This is the interface for LLVM&#39;s primary stateless and local alias analysis.
A single uniqued string.
Definition: Metadata.h:602
A container for analyses that lazily runs them and caches their results.
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:262
static cl::opt< std::string > ClReadSummary("wholeprogramdevirt-read-summary", cl::desc("Read summary from given bitcode or YAML file before running pass"), cl::Hidden)
void updateVCallVisibilityInModule(Module &M, bool WholeProgramVisibilityEnabledInLTO)
If whole program visibility asserted, then upgrade all public vcall visibility metadata on vtable def...
Root of the metadata hierarchy.
Definition: Metadata.h:58
static IntegerType * getInt8Ty(LLVMContext &C)
Definition: Type.cpp:184
void setSection(StringRef S)
Change the section for this global.
Definition: Globals.cpp:211
The optimization diagnostic interface.
static unsigned getHashValue(const VTableSlotSummary &I)
bool use_empty() const
Definition: Value.h:341
Constant * getPointerAtOffset(Constant *I, uint64_t Offset, Module &M)
static GlobalAlias * create(Type *Ty, unsigned AddressSpace, LinkageTypes Linkage, const Twine &Name, Constant *Aliasee, Module *Parent)
If a parent module is specified, the alias is automatically inserted into the end of the specified mo...
Definition: Globals.cpp:480
constexpr char Args[]
Key for Kernel::Metadata::mArgs.
The following data structures summarize type metadata information.
Error createStringError(std::error_code EC, char const *Fmt, const Ts &... Vals)
Create formatted StringError object.
Definition: Error.h:1202
static AttributeList get(LLVMContext &C, ArrayRef< std::pair< unsigned, Attribute >> Attrs)
Create an AttributeList with the specified parameters in it.
IntegerType * Int32Ty
const BasicBlock * getParent() const
Definition: Instruction.h:94
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
An analysis over an "outer" IR unit that provides access to an analysis manager over an "inner" IR un...
Definition: PassManager.h:953