LLVM  10.0.0svn
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"
65 #include "llvm/IR/CallSite.h"
66 #include "llvm/IR/Constants.h"
67 #include "llvm/IR/DataLayout.h"
68 #include "llvm/IR/DebugLoc.h"
69 #include "llvm/IR/DerivedTypes.h"
70 #include "llvm/IR/Dominators.h"
71 #include "llvm/IR/Function.h"
72 #include "llvm/IR/GlobalAlias.h"
73 #include "llvm/IR/GlobalVariable.h"
74 #include "llvm/IR/IRBuilder.h"
75 #include "llvm/IR/InstrTypes.h"
76 #include "llvm/IR/Instruction.h"
77 #include "llvm/IR/Instructions.h"
78 #include "llvm/IR/Intrinsics.h"
79 #include "llvm/IR/LLVMContext.h"
80 #include "llvm/IR/Metadata.h"
81 #include "llvm/IR/Module.h"
83 #include "llvm/Pass.h"
84 #include "llvm/PassRegistry.h"
85 #include "llvm/PassSupport.h"
86 #include "llvm/Support/Casting.h"
87 #include "llvm/Support/Error.h"
90 #include "llvm/Transforms/IPO.h"
93 #include <algorithm>
94 #include <cstddef>
95 #include <map>
96 #include <set>
97 #include <string>
98 
99 using namespace llvm;
100 using namespace wholeprogramdevirt;
101 
102 #define DEBUG_TYPE "wholeprogramdevirt"
103 
105  "wholeprogramdevirt-summary-action",
106  cl::desc("What to do with the summary when running this pass"),
107  cl::values(clEnumValN(PassSummaryAction::None, "none", "Do nothing"),
109  "Import typeid resolutions from summary and globals"),
111  "Export typeid resolutions to summary and globals")),
112  cl::Hidden);
113 
115  "wholeprogramdevirt-read-summary",
116  cl::desc("Read summary from given YAML file before running pass"),
117  cl::Hidden);
118 
120  "wholeprogramdevirt-write-summary",
121  cl::desc("Write summary to given YAML file after running pass"),
122  cl::Hidden);
123 
124 static cl::opt<unsigned>
125  ClThreshold("wholeprogramdevirt-branch-funnel-threshold", cl::Hidden,
127  cl::desc("Maximum number of call targets per "
128  "call site to enable branch funnels"));
129 
130 static cl::opt<bool>
131  PrintSummaryDevirt("wholeprogramdevirt-print-index-based", cl::Hidden,
132  cl::init(false), cl::ZeroOrMore,
133  cl::desc("Print index-based devirtualization messages"));
134 
135 // Find the minimum offset that we may store a value of size Size bits at. If
136 // IsAfter is set, look for an offset before the object, otherwise look for an
137 // offset after the object.
138 uint64_t
140  bool IsAfter, uint64_t Size) {
141  // Find a minimum offset taking into account only vtable sizes.
142  uint64_t MinByte = 0;
143  for (const VirtualCallTarget &Target : Targets) {
144  if (IsAfter)
145  MinByte = std::max(MinByte, Target.minAfterBytes());
146  else
147  MinByte = std::max(MinByte, Target.minBeforeBytes());
148  }
149 
150  // Build a vector of arrays of bytes covering, for each target, a slice of the
151  // used region (see AccumBitVector::BytesUsed in
152  // llvm/Transforms/IPO/WholeProgramDevirt.h) starting at MinByte. Effectively,
153  // this aligns the used regions to start at MinByte.
154  //
155  // In this example, A, B and C are vtables, # is a byte already allocated for
156  // a virtual function pointer, AAAA... (etc.) are the used regions for the
157  // vtables and Offset(X) is the value computed for the Offset variable below
158  // for X.
159  //
160  // Offset(A)
161  // | |
162  // |MinByte
163  // A: ################AAAAAAAA|AAAAAAAA
164  // B: ########BBBBBBBBBBBBBBBB|BBBB
165  // C: ########################|CCCCCCCCCCCCCCCC
166  // | Offset(B) |
167  //
168  // This code produces the slices of A, B and C that appear after the divider
169  // at MinByte.
170  std::vector<ArrayRef<uint8_t>> Used;
171  for (const VirtualCallTarget &Target : Targets) {
172  ArrayRef<uint8_t> VTUsed = IsAfter ? Target.TM->Bits->After.BytesUsed
173  : Target.TM->Bits->Before.BytesUsed;
174  uint64_t Offset = IsAfter ? MinByte - Target.minAfterBytes()
175  : MinByte - Target.minBeforeBytes();
176 
177  // Disregard used regions that are smaller than Offset. These are
178  // effectively all-free regions that do not need to be checked.
179  if (VTUsed.size() > Offset)
180  Used.push_back(VTUsed.slice(Offset));
181  }
182 
183  if (Size == 1) {
184  // Find a free bit in each member of Used.
185  for (unsigned I = 0;; ++I) {
186  uint8_t BitsUsed = 0;
187  for (auto &&B : Used)
188  if (I < B.size())
189  BitsUsed |= B[I];
190  if (BitsUsed != 0xff)
191  return (MinByte + I) * 8 +
192  countTrailingZeros(uint8_t(~BitsUsed), ZB_Undefined);
193  }
194  } else {
195  // Find a free (Size/8) byte region in each member of Used.
196  // FIXME: see if alignment helps.
197  for (unsigned I = 0;; ++I) {
198  for (auto &&B : Used) {
199  unsigned Byte = 0;
200  while ((I + Byte) < B.size() && Byte < (Size / 8)) {
201  if (B[I + Byte])
202  goto NextI;
203  ++Byte;
204  }
205  }
206  return (MinByte + I) * 8;
207  NextI:;
208  }
209  }
210 }
211 
213  MutableArrayRef<VirtualCallTarget> Targets, uint64_t AllocBefore,
214  unsigned BitWidth, int64_t &OffsetByte, uint64_t &OffsetBit) {
215  if (BitWidth == 1)
216  OffsetByte = -(AllocBefore / 8 + 1);
217  else
218  OffsetByte = -((AllocBefore + 7) / 8 + (BitWidth + 7) / 8);
219  OffsetBit = AllocBefore % 8;
220 
221  for (VirtualCallTarget &Target : Targets) {
222  if (BitWidth == 1)
223  Target.setBeforeBit(AllocBefore);
224  else
225  Target.setBeforeBytes(AllocBefore, (BitWidth + 7) / 8);
226  }
227 }
228 
230  MutableArrayRef<VirtualCallTarget> Targets, uint64_t AllocAfter,
231  unsigned BitWidth, int64_t &OffsetByte, uint64_t &OffsetBit) {
232  if (BitWidth == 1)
233  OffsetByte = AllocAfter / 8;
234  else
235  OffsetByte = (AllocAfter + 7) / 8;
236  OffsetBit = AllocAfter % 8;
237 
238  for (VirtualCallTarget &Target : Targets) {
239  if (BitWidth == 1)
240  Target.setAfterBit(AllocAfter);
241  else
242  Target.setAfterBytes(AllocAfter, (BitWidth + 7) / 8);
243  }
244 }
245 
247  : Fn(Fn), TM(TM),
248  IsBigEndian(Fn->getParent()->getDataLayout().isBigEndian()), WasDevirt(false) {}
249 
250 namespace {
251 
252 // A slot in a set of virtual tables. The TypeID identifies the set of virtual
253 // tables, and the ByteOffset is the offset in bytes from the address point to
254 // the virtual function pointer.
255 struct VTableSlot {
256  Metadata *TypeID;
257  uint64_t ByteOffset;
258 };
259 
260 } // end anonymous namespace
261 
262 namespace llvm {
263 
264 template <> struct DenseMapInfo<VTableSlot> {
265  static VTableSlot getEmptyKey() {
268  }
269  static VTableSlot getTombstoneKey() {
272  }
273  static unsigned getHashValue(const VTableSlot &I) {
274  return DenseMapInfo<Metadata *>::getHashValue(I.TypeID) ^
276  }
277  static bool isEqual(const VTableSlot &LHS,
278  const VTableSlot &RHS) {
279  return LHS.TypeID == RHS.TypeID && LHS.ByteOffset == RHS.ByteOffset;
280  }
281 };
282 
283 template <> struct DenseMapInfo<VTableSlotSummary> {
287  }
291  }
292  static unsigned getHashValue(const VTableSlotSummary &I) {
295  }
296  static bool isEqual(const VTableSlotSummary &LHS,
297  const VTableSlotSummary &RHS) {
298  return LHS.TypeID == RHS.TypeID && LHS.ByteOffset == RHS.ByteOffset;
299  }
300 };
301 
302 } // end namespace llvm
303 
304 namespace {
305 
306 // A virtual call site. VTable is the loaded virtual table pointer, and CS is
307 // the indirect virtual call.
308 struct VirtualCallSite {
309  Value *VTable;
310  CallSite CS;
311 
312  // If non-null, this field points to the associated unsafe use count stored in
313  // the DevirtModule::NumUnsafeUsesForTypeTest map below. See the description
314  // of that field for details.
315  unsigned *NumUnsafeUses;
316 
317  void
318  emitRemark(const StringRef OptName, const StringRef TargetName,
320  Function *F = CS.getCaller();
321  DebugLoc DLoc = CS->getDebugLoc();
322  BasicBlock *Block = CS.getParent();
323 
324  using namespace ore;
325  OREGetter(F).emit(OptimizationRemark(DEBUG_TYPE, OptName, DLoc, Block)
326  << NV("Optimization", OptName)
327  << ": devirtualized a call to "
328  << NV("FunctionName", TargetName));
329  }
330 
331  void replaceAndErase(
332  const StringRef OptName, const StringRef TargetName, bool RemarksEnabled,
334  Value *New) {
335  if (RemarksEnabled)
336  emitRemark(OptName, TargetName, OREGetter);
337  CS->replaceAllUsesWith(New);
338  if (auto II = dyn_cast<InvokeInst>(CS.getInstruction())) {
339  BranchInst::Create(II->getNormalDest(), CS.getInstruction());
340  II->getUnwindDest()->removePredecessor(II->getParent());
341  }
342  CS->eraseFromParent();
343  // This use is no longer unsafe.
344  if (NumUnsafeUses)
345  --*NumUnsafeUses;
346  }
347 };
348 
349 // Call site information collected for a specific VTableSlot and possibly a list
350 // of constant integer arguments. The grouping by arguments is handled by the
351 // VTableSlotInfo class.
352 struct CallSiteInfo {
353  /// The set of call sites for this slot. Used during regular LTO and the
354  /// import phase of ThinLTO (as well as the export phase of ThinLTO for any
355  /// call sites that appear in the merged module itself); in each of these
356  /// cases we are directly operating on the call sites at the IR level.
357  std::vector<VirtualCallSite> CallSites;
358 
359  /// Whether all call sites represented by this CallSiteInfo, including those
360  /// in summaries, have been devirtualized. This starts off as true because a
361  /// default constructed CallSiteInfo represents no call sites.
362  bool AllCallSitesDevirted = true;
363 
364  // These fields are used during the export phase of ThinLTO and reflect
365  // information collected from function summaries.
366 
367  /// Whether any function summary contains an llvm.assume(llvm.type.test) for
368  /// this slot.
369  bool SummaryHasTypeTestAssumeUsers = false;
370 
371  /// CFI-specific: a vector containing the list of function summaries that use
372  /// the llvm.type.checked.load intrinsic and therefore will require
373  /// resolutions for llvm.type.test in order to implement CFI checks if
374  /// devirtualization was unsuccessful. If devirtualization was successful, the
375  /// pass will clear this vector by calling markDevirt(). If at the end of the
376  /// pass the vector is non-empty, we will need to add a use of llvm.type.test
377  /// to each of the function summaries in the vector.
378  std::vector<FunctionSummary *> SummaryTypeCheckedLoadUsers;
379  std::vector<FunctionSummary *> SummaryTypeTestAssumeUsers;
380 
381  bool isExported() const {
382  return SummaryHasTypeTestAssumeUsers ||
383  !SummaryTypeCheckedLoadUsers.empty();
384  }
385 
386  void markSummaryHasTypeTestAssumeUsers() {
387  SummaryHasTypeTestAssumeUsers = true;
388  AllCallSitesDevirted = false;
389  }
390 
391  void addSummaryTypeCheckedLoadUser(FunctionSummary *FS) {
392  SummaryTypeCheckedLoadUsers.push_back(FS);
393  AllCallSitesDevirted = false;
394  }
395 
396  void addSummaryTypeTestAssumeUser(FunctionSummary *FS) {
397  SummaryTypeTestAssumeUsers.push_back(FS);
398  markSummaryHasTypeTestAssumeUsers();
399  }
400 
401  void markDevirt() {
402  AllCallSitesDevirted = true;
403 
404  // As explained in the comment for SummaryTypeCheckedLoadUsers.
405  SummaryTypeCheckedLoadUsers.clear();
406  }
407 };
408 
409 // Call site information collected for a specific VTableSlot.
410 struct VTableSlotInfo {
411  // The set of call sites which do not have all constant integer arguments
412  // (excluding "this").
413  CallSiteInfo CSInfo;
414 
415  // The set of call sites with all constant integer arguments (excluding
416  // "this"), grouped by argument list.
417  std::map<std::vector<uint64_t>, CallSiteInfo> ConstCSInfo;
418 
419  void addCallSite(Value *VTable, CallSite CS, unsigned *NumUnsafeUses);
420 
421 private:
422  CallSiteInfo &findCallSiteInfo(CallSite CS);
423 };
424 
425 CallSiteInfo &VTableSlotInfo::findCallSiteInfo(CallSite CS) {
426  std::vector<uint64_t> Args;
427  auto *CI = dyn_cast<IntegerType>(CS.getType());
428  if (!CI || CI->getBitWidth() > 64 || CS.arg_empty())
429  return CSInfo;
430  for (auto &&Arg : make_range(CS.arg_begin() + 1, CS.arg_end())) {
431  auto *CI = dyn_cast<ConstantInt>(Arg);
432  if (!CI || CI->getBitWidth() > 64)
433  return CSInfo;
434  Args.push_back(CI->getZExtValue());
435  }
436  return ConstCSInfo[Args];
437 }
438 
439 void VTableSlotInfo::addCallSite(Value *VTable, CallSite CS,
440  unsigned *NumUnsafeUses) {
441  auto &CSI = findCallSiteInfo(CS);
442  CSI.AllCallSitesDevirted = false;
443  CSI.CallSites.push_back({VTable, CS, NumUnsafeUses});
444 }
445 
446 struct DevirtModule {
447  Module &M;
450 
451  ModuleSummaryIndex *ExportSummary;
452  const ModuleSummaryIndex *ImportSummary;
453 
454  IntegerType *Int8Ty;
455  PointerType *Int8PtrTy;
457  IntegerType *Int64Ty;
458  IntegerType *IntPtrTy;
459 
460  bool RemarksEnabled;
462 
464 
465  // This map keeps track of the number of "unsafe" uses of a loaded function
466  // pointer. The key is the associated llvm.type.test intrinsic call generated
467  // by this pass. An unsafe use is one that calls the loaded function pointer
468  // directly. Every time we eliminate an unsafe use (for example, by
469  // devirtualizing it or by applying virtual constant propagation), we
470  // decrement the value stored in this map. If a value reaches zero, we can
471  // eliminate the type check by RAUWing the associated llvm.type.test call with
472  // true.
473  std::map<CallInst *, unsigned> NumUnsafeUsesForTypeTest;
474 
475  DevirtModule(Module &M, function_ref<AAResults &(Function &)> AARGetter,
477  function_ref<DominatorTree &(Function &)> LookupDomTree,
478  ModuleSummaryIndex *ExportSummary,
479  const ModuleSummaryIndex *ImportSummary)
480  : M(M), AARGetter(AARGetter), LookupDomTree(LookupDomTree),
481  ExportSummary(ExportSummary), ImportSummary(ImportSummary),
482  Int8Ty(Type::getInt8Ty(M.getContext())),
483  Int8PtrTy(Type::getInt8PtrTy(M.getContext())),
485  Int64Ty(Type::getInt64Ty(M.getContext())),
486  IntPtrTy(M.getDataLayout().getIntPtrType(M.getContext(), 0)),
487  RemarksEnabled(areRemarksEnabled()), OREGetter(OREGetter) {
488  assert(!(ExportSummary && ImportSummary));
489  }
490 
491  bool areRemarksEnabled();
492 
493  void scanTypeTestUsers(Function *TypeTestFunc, Function *AssumeFunc);
494  void scanTypeCheckedLoadUsers(Function *TypeCheckedLoadFunc);
495 
496  void buildTypeIdentifierMap(
497  std::vector<VTableBits> &Bits,
498  DenseMap<Metadata *, std::set<TypeMemberInfo>> &TypeIdMap);
499  Constant *getPointerAtOffset(Constant *I, uint64_t Offset);
500  bool
501  tryFindVirtualCallTargets(std::vector<VirtualCallTarget> &TargetsForSlot,
502  const std::set<TypeMemberInfo> &TypeMemberInfos,
503  uint64_t ByteOffset);
504 
505  void applySingleImplDevirt(VTableSlotInfo &SlotInfo, Constant *TheFn,
506  bool &IsExported);
507  bool trySingleImplDevirt(MutableArrayRef<VirtualCallTarget> TargetsForSlot,
508  VTableSlotInfo &SlotInfo,
510 
511  void applyICallBranchFunnel(VTableSlotInfo &SlotInfo, Constant *JT,
512  bool &IsExported);
513  void tryICallBranchFunnel(MutableArrayRef<VirtualCallTarget> TargetsForSlot,
514  VTableSlotInfo &SlotInfo,
515  WholeProgramDevirtResolution *Res, VTableSlot Slot);
516 
517  bool tryEvaluateFunctionsWithArgs(
518  MutableArrayRef<VirtualCallTarget> TargetsForSlot,
520 
521  void applyUniformRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
522  uint64_t TheRetVal);
523  bool tryUniformRetValOpt(MutableArrayRef<VirtualCallTarget> TargetsForSlot,
524  CallSiteInfo &CSInfo,
526 
527  // Returns the global symbol name that is used to export information about the
528  // given vtable slot and list of arguments.
529  std::string getGlobalName(VTableSlot Slot, ArrayRef<uint64_t> Args,
530  StringRef Name);
531 
532  bool shouldExportConstantsAsAbsoluteSymbols();
533 
534  // This function is called during the export phase to create a symbol
535  // definition containing information about the given vtable slot and list of
536  // arguments.
537  void exportGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args, StringRef Name,
538  Constant *C);
539  void exportConstant(VTableSlot Slot, ArrayRef<uint64_t> Args, StringRef Name,
540  uint32_t Const, uint32_t &Storage);
541 
542  // This function is called during the import phase to create a reference to
543  // the symbol definition created during the export phase.
544  Constant *importGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
545  StringRef Name);
546  Constant *importConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
547  StringRef Name, IntegerType *IntTy,
548  uint32_t Storage);
549 
550  Constant *getMemberAddr(const TypeMemberInfo *M);
551 
552  void applyUniqueRetValOpt(CallSiteInfo &CSInfo, StringRef FnName, bool IsOne,
553  Constant *UniqueMemberAddr);
554  bool tryUniqueRetValOpt(unsigned BitWidth,
555  MutableArrayRef<VirtualCallTarget> TargetsForSlot,
556  CallSiteInfo &CSInfo,
558  VTableSlot Slot, ArrayRef<uint64_t> Args);
559 
560  void applyVirtualConstProp(CallSiteInfo &CSInfo, StringRef FnName,
561  Constant *Byte, Constant *Bit);
562  bool tryVirtualConstProp(MutableArrayRef<VirtualCallTarget> TargetsForSlot,
563  VTableSlotInfo &SlotInfo,
564  WholeProgramDevirtResolution *Res, VTableSlot Slot);
565 
566  void rebuildGlobal(VTableBits &B);
567 
568  // Apply the summary resolution for Slot to all virtual calls in SlotInfo.
569  void importResolution(VTableSlot Slot, VTableSlotInfo &SlotInfo);
570 
571  // If we were able to eliminate all unsafe uses for a type checked load,
572  // eliminate the associated type tests by replacing them with true.
573  void removeRedundantTypeTests();
574 
575  bool run();
576 
577  // Lower the module using the action and summary passed as command line
578  // arguments. For testing purposes only.
579  static bool
580  runForTesting(Module &M, function_ref<AAResults &(Function &)> AARGetter,
582  function_ref<DominatorTree &(Function &)> LookupDomTree);
583 };
584 
585 struct DevirtIndex {
586  ModuleSummaryIndex &ExportSummary;
587  // The set in which to record GUIDs exported from their module by
588  // devirtualization, used by client to ensure they are not internalized.
589  std::set<GlobalValue::GUID> &ExportedGUIDs;
590  // A map in which to record the information necessary to locate the WPD
591  // resolution for local targets in case they are exported by cross module
592  // importing.
593  std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap;
594 
596 
597  DevirtIndex(
598  ModuleSummaryIndex &ExportSummary,
599  std::set<GlobalValue::GUID> &ExportedGUIDs,
600  std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap)
601  : ExportSummary(ExportSummary), ExportedGUIDs(ExportedGUIDs),
602  LocalWPDTargetsMap(LocalWPDTargetsMap) {}
603 
604  bool tryFindVirtualCallTargets(std::vector<ValueInfo> &TargetsForSlot,
605  const TypeIdCompatibleVtableInfo TIdInfo,
606  uint64_t ByteOffset);
607 
608  bool trySingleImplDevirt(MutableArrayRef<ValueInfo> TargetsForSlot,
609  VTableSlotSummary &SlotSummary,
610  VTableSlotInfo &SlotInfo,
612  std::set<ValueInfo> &DevirtTargets);
613 
614  void run();
615 };
616 
617 struct WholeProgramDevirt : public ModulePass {
618  static char ID;
619 
620  bool UseCommandLine = false;
621 
622  ModuleSummaryIndex *ExportSummary;
623  const ModuleSummaryIndex *ImportSummary;
624 
625  WholeProgramDevirt() : ModulePass(ID), UseCommandLine(true) {
627  }
628 
629  WholeProgramDevirt(ModuleSummaryIndex *ExportSummary,
630  const ModuleSummaryIndex *ImportSummary)
631  : ModulePass(ID), ExportSummary(ExportSummary),
632  ImportSummary(ImportSummary) {
634  }
635 
636  bool runOnModule(Module &M) override {
637  if (skipModule(M))
638  return false;
639 
640  // In the new pass manager, we can request the optimization
641  // remark emitter pass on a per-function-basis, which the
642  // OREGetter will do for us.
643  // In the old pass manager, this is harder, so we just build
644  // an optimization remark emitter on the fly, when we need it.
645  std::unique_ptr<OptimizationRemarkEmitter> ORE;
646  auto OREGetter = [&](Function *F) -> OptimizationRemarkEmitter & {
647  ORE = std::make_unique<OptimizationRemarkEmitter>(F);
648  return *ORE;
649  };
650 
651  auto LookupDomTree = [this](Function &F) -> DominatorTree & {
652  return this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
653  };
654 
655  if (UseCommandLine)
656  return DevirtModule::runForTesting(M, LegacyAARGetter(*this), OREGetter,
657  LookupDomTree);
658 
659  return DevirtModule(M, LegacyAARGetter(*this), OREGetter, LookupDomTree,
660  ExportSummary, ImportSummary)
661  .run();
662  }
663 
664  void getAnalysisUsage(AnalysisUsage &AU) const override {
668  }
669 };
670 
671 } // end anonymous namespace
672 
673 INITIALIZE_PASS_BEGIN(WholeProgramDevirt, "wholeprogramdevirt",
674  "Whole program devirtualization", false, false)
679  "Whole program devirtualization", false, false)
680 char WholeProgramDevirt::ID = 0;
681 
682 ModulePass *
684  const ModuleSummaryIndex *ImportSummary) {
685  return new WholeProgramDevirt(ExportSummary, ImportSummary);
686 }
687 
689  ModuleAnalysisManager &AM) {
690  auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
691  auto AARGetter = [&](Function &F) -> AAResults & {
692  return FAM.getResult<AAManager>(F);
693  };
694  auto OREGetter = [&](Function *F) -> OptimizationRemarkEmitter & {
695  return FAM.getResult<OptimizationRemarkEmitterAnalysis>(*F);
696  };
697  auto LookupDomTree = [&FAM](Function &F) -> DominatorTree & {
698  return FAM.getResult<DominatorTreeAnalysis>(F);
699  };
700  if (!DevirtModule(M, AARGetter, OREGetter, LookupDomTree, ExportSummary,
701  ImportSummary)
702  .run())
703  return PreservedAnalyses::all();
704  return PreservedAnalyses::none();
705 }
706 
707 namespace llvm {
709  ModuleSummaryIndex &Summary, std::set<GlobalValue::GUID> &ExportedGUIDs,
710  std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap) {
711  DevirtIndex(Summary, ExportedGUIDs, LocalWPDTargetsMap).run();
712 }
713 
715  ModuleSummaryIndex &Summary,
717  std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap) {
718  for (auto &T : LocalWPDTargetsMap) {
719  auto &VI = T.first;
720  // This was enforced earlier during trySingleImplDevirt.
721  assert(VI.getSummaryList().size() == 1 &&
722  "Devirt of local target has more than one copy");
723  auto &S = VI.getSummaryList()[0];
724  const auto &ExportList = ExportLists.find(S->modulePath());
725  if (ExportList == ExportLists.end() ||
726  !ExportList->second.count(VI.getGUID()))
727  continue;
728 
729  // It's been exported by a cross module import.
730  for (auto &SlotSummary : T.second) {
731  auto *TIdSum = Summary.getTypeIdSummary(SlotSummary.TypeID);
732  assert(TIdSum);
733  auto WPDRes = TIdSum->WPDRes.find(SlotSummary.ByteOffset);
734  assert(WPDRes != TIdSum->WPDRes.end());
735  WPDRes->second.SingleImplName = ModuleSummaryIndex::getGlobalNameForLocal(
736  WPDRes->second.SingleImplName,
737  Summary.getModuleHash(S->modulePath()));
738  }
739  }
740 }
741 
742 } // end namespace llvm
743 
744 bool DevirtModule::runForTesting(
745  Module &M, function_ref<AAResults &(Function &)> AARGetter,
747  function_ref<DominatorTree &(Function &)> LookupDomTree) {
748  ModuleSummaryIndex Summary(/*HaveGVs=*/false);
749 
750  // Handle the command-line summary arguments. This code is for testing
751  // purposes only, so we handle errors directly.
752  if (!ClReadSummary.empty()) {
753  ExitOnError ExitOnErr("-wholeprogramdevirt-read-summary: " + ClReadSummary +
754  ": ");
755  auto ReadSummaryFile =
757 
758  yaml::Input In(ReadSummaryFile->getBuffer());
759  In >> Summary;
760  ExitOnErr(errorCodeToError(In.error()));
761  }
762 
763  bool Changed =
764  DevirtModule(
765  M, AARGetter, OREGetter, LookupDomTree,
766  ClSummaryAction == PassSummaryAction::Export ? &Summary : nullptr,
767  ClSummaryAction == PassSummaryAction::Import ? &Summary : nullptr)
768  .run();
769 
770  if (!ClWriteSummary.empty()) {
771  ExitOnError ExitOnErr(
772  "-wholeprogramdevirt-write-summary: " + ClWriteSummary + ": ");
773  std::error_code EC;
775  ExitOnErr(errorCodeToError(EC));
776 
777  yaml::Output Out(OS);
778  Out << Summary;
779  }
780 
781  return Changed;
782 }
783 
784 void DevirtModule::buildTypeIdentifierMap(
785  std::vector<VTableBits> &Bits,
786  DenseMap<Metadata *, std::set<TypeMemberInfo>> &TypeIdMap) {
788  Bits.reserve(M.getGlobalList().size());
790  for (GlobalVariable &GV : M.globals()) {
791  Types.clear();
792  GV.getMetadata(LLVMContext::MD_type, Types);
793  if (GV.isDeclaration() || Types.empty())
794  continue;
795 
796  VTableBits *&BitsPtr = GVToBits[&GV];
797  if (!BitsPtr) {
798  Bits.emplace_back();
799  Bits.back().GV = &GV;
800  Bits.back().ObjectSize =
801  M.getDataLayout().getTypeAllocSize(GV.getInitializer()->getType());
802  BitsPtr = &Bits.back();
803  }
804 
805  for (MDNode *Type : Types) {
806  auto TypeID = Type->getOperand(1).get();
807 
808  uint64_t Offset =
809  cast<ConstantInt>(
810  cast<ConstantAsMetadata>(Type->getOperand(0))->getValue())
811  ->getZExtValue();
812 
813  TypeIdMap[TypeID].insert({BitsPtr, Offset});
814  }
815  }
816 }
817 
818 Constant *DevirtModule::getPointerAtOffset(Constant *I, uint64_t Offset) {
819  if (I->getType()->isPointerTy()) {
820  if (Offset == 0)
821  return I;
822  return nullptr;
823  }
824 
825  const DataLayout &DL = M.getDataLayout();
826 
827  if (auto *C = dyn_cast<ConstantStruct>(I)) {
828  const StructLayout *SL = DL.getStructLayout(C->getType());
829  if (Offset >= SL->getSizeInBytes())
830  return nullptr;
831 
832  unsigned Op = SL->getElementContainingOffset(Offset);
833  return getPointerAtOffset(cast<Constant>(I->getOperand(Op)),
834  Offset - SL->getElementOffset(Op));
835  }
836  if (auto *C = dyn_cast<ConstantArray>(I)) {
837  ArrayType *VTableTy = C->getType();
838  uint64_t ElemSize = DL.getTypeAllocSize(VTableTy->getElementType());
839 
840  unsigned Op = Offset / ElemSize;
841  if (Op >= C->getNumOperands())
842  return nullptr;
843 
844  return getPointerAtOffset(cast<Constant>(I->getOperand(Op)),
845  Offset % ElemSize);
846  }
847  return nullptr;
848 }
849 
850 bool DevirtModule::tryFindVirtualCallTargets(
851  std::vector<VirtualCallTarget> &TargetsForSlot,
852  const std::set<TypeMemberInfo> &TypeMemberInfos, uint64_t ByteOffset) {
853  for (const TypeMemberInfo &TM : TypeMemberInfos) {
854  if (!TM.Bits->GV->isConstant())
855  return false;
856 
857  Constant *Ptr = getPointerAtOffset(TM.Bits->GV->getInitializer(),
858  TM.Offset + ByteOffset);
859  if (!Ptr)
860  return false;
861 
862  auto Fn = dyn_cast<Function>(Ptr->stripPointerCasts());
863  if (!Fn)
864  return false;
865 
866  // We can disregard __cxa_pure_virtual as a possible call target, as
867  // calls to pure virtuals are UB.
868  if (Fn->getName() == "__cxa_pure_virtual")
869  continue;
870 
871  TargetsForSlot.push_back({Fn, &TM});
872  }
873 
874  // Give up if we couldn't find any targets.
875  return !TargetsForSlot.empty();
876 }
877 
878 bool DevirtIndex::tryFindVirtualCallTargets(
879  std::vector<ValueInfo> &TargetsForSlot, const TypeIdCompatibleVtableInfo TIdInfo,
880  uint64_t ByteOffset) {
881  for (const TypeIdOffsetVtableInfo P : TIdInfo) {
882  // VTable initializer should have only one summary, or all copies must be
883  // linkonce/weak ODR.
884  assert(P.VTableVI.getSummaryList().size() == 1 ||
885  llvm::all_of(
886  P.VTableVI.getSummaryList(),
887  [&](const std::unique_ptr<GlobalValueSummary> &Summary) {
888  return GlobalValue::isLinkOnceODRLinkage(Summary->linkage()) ||
889  GlobalValue::isWeakODRLinkage(Summary->linkage());
890  }));
891  const auto *VS = cast<GlobalVarSummary>(P.VTableVI.getSummaryList()[0].get());
892  if (!P.VTableVI.getSummaryList()[0]->isLive())
893  continue;
894  for (auto VTP : VS->vTableFuncs()) {
895  if (VTP.VTableOffset != P.AddressPointOffset + ByteOffset)
896  continue;
897 
898  TargetsForSlot.push_back(VTP.FuncVI);
899  }
900  }
901 
902  // Give up if we couldn't find any targets.
903  return !TargetsForSlot.empty();
904 }
905 
906 void DevirtModule::applySingleImplDevirt(VTableSlotInfo &SlotInfo,
907  Constant *TheFn, bool &IsExported) {
908  auto Apply = [&](CallSiteInfo &CSInfo) {
909  for (auto &&VCallSite : CSInfo.CallSites) {
910  if (RemarksEnabled)
911  VCallSite.emitRemark("single-impl",
912  TheFn->stripPointerCasts()->getName(), OREGetter);
913  VCallSite.CS.setCalledFunction(ConstantExpr::getBitCast(
914  TheFn, VCallSite.CS.getCalledValue()->getType()));
915  // This use is no longer unsafe.
916  if (VCallSite.NumUnsafeUses)
917  --*VCallSite.NumUnsafeUses;
918  }
919  if (CSInfo.isExported())
920  IsExported = true;
921  CSInfo.markDevirt();
922  };
923  Apply(SlotInfo.CSInfo);
924  for (auto &P : SlotInfo.ConstCSInfo)
925  Apply(P.second);
926 }
927 
928 bool DevirtModule::trySingleImplDevirt(
929  MutableArrayRef<VirtualCallTarget> TargetsForSlot,
930  VTableSlotInfo &SlotInfo, WholeProgramDevirtResolution *Res) {
931  // See if the program contains a single implementation of this virtual
932  // function.
933  Function *TheFn = TargetsForSlot[0].Fn;
934  for (auto &&Target : TargetsForSlot)
935  if (TheFn != Target.Fn)
936  return false;
937 
938  // If so, update each call site to call that implementation directly.
939  if (RemarksEnabled)
940  TargetsForSlot[0].WasDevirt = true;
941 
942  bool IsExported = false;
943  applySingleImplDevirt(SlotInfo, TheFn, IsExported);
944  if (!IsExported)
945  return false;
946 
947  // If the only implementation has local linkage, we must promote to external
948  // to make it visible to thin LTO objects. We can only get here during the
949  // ThinLTO export phase.
950  if (TheFn->hasLocalLinkage()) {
951  std::string NewName = (TheFn->getName() + "$merged").str();
952 
953  // Since we are renaming the function, any comdats with the same name must
954  // also be renamed. This is required when targeting COFF, as the comdat name
955  // must match one of the names of the symbols in the comdat.
956  if (Comdat *C = TheFn->getComdat()) {
957  if (C->getName() == TheFn->getName()) {
958  Comdat *NewC = M.getOrInsertComdat(NewName);
959  NewC->setSelectionKind(C->getSelectionKind());
960  for (GlobalObject &GO : M.global_objects())
961  if (GO.getComdat() == C)
962  GO.setComdat(NewC);
963  }
964  }
965 
968  TheFn->setName(NewName);
969  }
970 
972  Res->SingleImplName = TheFn->getName();
973 
974  return true;
975 }
976 
977 bool DevirtIndex::trySingleImplDevirt(MutableArrayRef<ValueInfo> TargetsForSlot,
978  VTableSlotSummary &SlotSummary,
979  VTableSlotInfo &SlotInfo,
981  std::set<ValueInfo> &DevirtTargets) {
982  // See if the program contains a single implementation of this virtual
983  // function.
984  auto TheFn = TargetsForSlot[0];
985  for (auto &&Target : TargetsForSlot)
986  if (TheFn != Target)
987  return false;
988 
989  // Don't devirtualize if we don't have target definition.
990  auto Size = TheFn.getSummaryList().size();
991  if (!Size)
992  return false;
993 
994  // If the summary list contains multiple summaries where at least one is
995  // a local, give up, as we won't know which (possibly promoted) name to use.
996  for (auto &S : TheFn.getSummaryList())
997  if (GlobalValue::isLocalLinkage(S->linkage()) && Size > 1)
998  return false;
999 
1000  // Collect functions devirtualized at least for one call site for stats.
1001  if (PrintSummaryDevirt)
1002  DevirtTargets.insert(TheFn);
1003 
1004  auto &S = TheFn.getSummaryList()[0];
1005  bool IsExported = false;
1006 
1007  // Insert calls into the summary index so that the devirtualized targets
1008  // are eligible for import.
1009  // FIXME: Annotate type tests with hotness. For now, mark these as hot
1010  // to better ensure we have the opportunity to inline them.
1011  CalleeInfo CI(CalleeInfo::HotnessType::Hot, /* RelBF = */ 0);
1012  auto AddCalls = [&](CallSiteInfo &CSInfo) {
1013  for (auto *FS : CSInfo.SummaryTypeCheckedLoadUsers) {
1014  FS->addCall({TheFn, CI});
1015  IsExported |= S->modulePath() != FS->modulePath();
1016  }
1017  for (auto *FS : CSInfo.SummaryTypeTestAssumeUsers) {
1018  FS->addCall({TheFn, CI});
1019  IsExported |= S->modulePath() != FS->modulePath();
1020  }
1021  };
1022  AddCalls(SlotInfo.CSInfo);
1023  for (auto &P : SlotInfo.ConstCSInfo)
1024  AddCalls(P.second);
1025 
1026  if (IsExported)
1027  ExportedGUIDs.insert(TheFn.getGUID());
1028 
1029  // Record in summary for use in devirtualization during the ThinLTO import
1030  // step.
1032  if (GlobalValue::isLocalLinkage(S->linkage())) {
1033  if (IsExported)
1034  // If target is a local function and we are exporting it by
1035  // devirtualizing a call in another module, we need to record the
1036  // promoted name.
1038  TheFn.name(), ExportSummary.getModuleHash(S->modulePath()));
1039  else {
1040  LocalWPDTargetsMap[TheFn].push_back(SlotSummary);
1041  Res->SingleImplName = TheFn.name();
1042  }
1043  } else
1044  Res->SingleImplName = TheFn.name();
1045 
1046  // Name will be empty if this thin link driven off of serialized combined
1047  // index (e.g. llvm-lto). However, WPD is not supported/invoked for the
1048  // legacy LTO API anyway.
1049  assert(!Res->SingleImplName.empty());
1050 
1051  return true;
1052 }
1053 
1054 void DevirtModule::tryICallBranchFunnel(
1055  MutableArrayRef<VirtualCallTarget> TargetsForSlot, VTableSlotInfo &SlotInfo,
1056  WholeProgramDevirtResolution *Res, VTableSlot Slot) {
1057  Triple T(M.getTargetTriple());
1058  if (T.getArch() != Triple::x86_64)
1059  return;
1060 
1061  if (TargetsForSlot.size() > ClThreshold)
1062  return;
1063 
1064  bool HasNonDevirt = !SlotInfo.CSInfo.AllCallSitesDevirted;
1065  if (!HasNonDevirt)
1066  for (auto &P : SlotInfo.ConstCSInfo)
1067  if (!P.second.AllCallSitesDevirted) {
1068  HasNonDevirt = true;
1069  break;
1070  }
1071 
1072  if (!HasNonDevirt)
1073  return;
1074 
1075  FunctionType *FT =
1076  FunctionType::get(Type::getVoidTy(M.getContext()), {Int8PtrTy}, true);
1077  Function *JT;
1078  if (isa<MDString>(Slot.TypeID)) {
1081  getGlobalName(Slot, {}, "branch_funnel"), &M);
1082  JT->setVisibility(GlobalValue::HiddenVisibility);
1083  } else {
1086  "branch_funnel", &M);
1087  }
1088  JT->addAttribute(1, Attribute::Nest);
1089 
1090  std::vector<Value *> JTArgs;
1091  JTArgs.push_back(JT->arg_begin());
1092  for (auto &T : TargetsForSlot) {
1093  JTArgs.push_back(getMemberAddr(T.TM));
1094  JTArgs.push_back(T.Fn);
1095  }
1096 
1097  BasicBlock *BB = BasicBlock::Create(M.getContext(), "", JT, nullptr);
1098  Function *Intr =
1099  Intrinsic::getDeclaration(&M, llvm::Intrinsic::icall_branch_funnel, {});
1100 
1101  auto *CI = CallInst::Create(Intr, JTArgs, "", BB);
1102  CI->setTailCallKind(CallInst::TCK_MustTail);
1103  ReturnInst::Create(M.getContext(), nullptr, BB);
1104 
1105  bool IsExported = false;
1106  applyICallBranchFunnel(SlotInfo, JT, IsExported);
1107  if (IsExported)
1109 }
1110 
1111 void DevirtModule::applyICallBranchFunnel(VTableSlotInfo &SlotInfo,
1112  Constant *JT, bool &IsExported) {
1113  auto Apply = [&](CallSiteInfo &CSInfo) {
1114  if (CSInfo.isExported())
1115  IsExported = true;
1116  if (CSInfo.AllCallSitesDevirted)
1117  return;
1118  for (auto &&VCallSite : CSInfo.CallSites) {
1119  CallSite CS = VCallSite.CS;
1120 
1121  // Jump tables are only profitable if the retpoline mitigation is enabled.
1122  Attribute FSAttr = CS.getCaller()->getFnAttribute("target-features");
1123  if (FSAttr.hasAttribute(Attribute::None) ||
1124  !FSAttr.getValueAsString().contains("+retpoline"))
1125  continue;
1126 
1127  if (RemarksEnabled)
1128  VCallSite.emitRemark("branch-funnel",
1129  JT->stripPointerCasts()->getName(), OREGetter);
1130 
1131  // Pass the address of the vtable in the nest register, which is r10 on
1132  // x86_64.
1133  std::vector<Type *> NewArgs;
1134  NewArgs.push_back(Int8PtrTy);
1135  for (Type *T : CS.getFunctionType()->params())
1136  NewArgs.push_back(T);
1137  FunctionType *NewFT =
1139  CS.getFunctionType()->isVarArg());
1140  PointerType *NewFTPtr = PointerType::getUnqual(NewFT);
1141 
1142  IRBuilder<> IRB(CS.getInstruction());
1143  std::vector<Value *> Args;
1144  Args.push_back(IRB.CreateBitCast(VCallSite.VTable, Int8PtrTy));
1145  for (unsigned I = 0; I != CS.getNumArgOperands(); ++I)
1146  Args.push_back(CS.getArgOperand(I));
1147 
1148  CallSite NewCS;
1149  if (CS.isCall())
1150  NewCS = IRB.CreateCall(NewFT, IRB.CreateBitCast(JT, NewFTPtr), Args);
1151  else
1152  NewCS = IRB.CreateInvoke(
1153  NewFT, IRB.CreateBitCast(JT, NewFTPtr),
1154  cast<InvokeInst>(CS.getInstruction())->getNormalDest(),
1155  cast<InvokeInst>(CS.getInstruction())->getUnwindDest(), Args);
1156  NewCS.setCallingConv(CS.getCallingConv());
1157 
1159  std::vector<AttributeSet> NewArgAttrs;
1160  NewArgAttrs.push_back(AttributeSet::get(
1162  M.getContext(), Attribute::Nest)}));
1163  for (unsigned I = 0; I + 2 < Attrs.getNumAttrSets(); ++I)
1164  NewArgAttrs.push_back(Attrs.getParamAttributes(I));
1165  NewCS.setAttributes(
1167  Attrs.getRetAttributes(), NewArgAttrs));
1168 
1169  CS->replaceAllUsesWith(NewCS.getInstruction());
1170  CS->eraseFromParent();
1171 
1172  // This use is no longer unsafe.
1173  if (VCallSite.NumUnsafeUses)
1174  --*VCallSite.NumUnsafeUses;
1175  }
1176  // Don't mark as devirtualized because there may be callers compiled without
1177  // retpoline mitigation, which would mean that they are lowered to
1178  // llvm.type.test and therefore require an llvm.type.test resolution for the
1179  // type identifier.
1180  };
1181  Apply(SlotInfo.CSInfo);
1182  for (auto &P : SlotInfo.ConstCSInfo)
1183  Apply(P.second);
1184 }
1185 
1186 bool DevirtModule::tryEvaluateFunctionsWithArgs(
1187  MutableArrayRef<VirtualCallTarget> TargetsForSlot,
1189  // Evaluate each function and store the result in each target's RetVal
1190  // field.
1191  for (VirtualCallTarget &Target : TargetsForSlot) {
1192  if (Target.Fn->arg_size() != Args.size() + 1)
1193  return false;
1194 
1195  Evaluator Eval(M.getDataLayout(), nullptr);
1196  SmallVector<Constant *, 2> EvalArgs;
1197  EvalArgs.push_back(
1198  Constant::getNullValue(Target.Fn->getFunctionType()->getParamType(0)));
1199  for (unsigned I = 0; I != Args.size(); ++I) {
1200  auto *ArgTy = dyn_cast<IntegerType>(
1201  Target.Fn->getFunctionType()->getParamType(I + 1));
1202  if (!ArgTy)
1203  return false;
1204  EvalArgs.push_back(ConstantInt::get(ArgTy, Args[I]));
1205  }
1206 
1207  Constant *RetVal;
1208  if (!Eval.EvaluateFunction(Target.Fn, RetVal, EvalArgs) ||
1209  !isa<ConstantInt>(RetVal))
1210  return false;
1211  Target.RetVal = cast<ConstantInt>(RetVal)->getZExtValue();
1212  }
1213  return true;
1214 }
1215 
1216 void DevirtModule::applyUniformRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
1217  uint64_t TheRetVal) {
1218  for (auto Call : CSInfo.CallSites)
1219  Call.replaceAndErase(
1220  "uniform-ret-val", FnName, RemarksEnabled, OREGetter,
1221  ConstantInt::get(cast<IntegerType>(Call.CS.getType()), TheRetVal));
1222  CSInfo.markDevirt();
1223 }
1224 
1225 bool DevirtModule::tryUniformRetValOpt(
1226  MutableArrayRef<VirtualCallTarget> TargetsForSlot, CallSiteInfo &CSInfo,
1228  // Uniform return value optimization. If all functions return the same
1229  // constant, replace all calls with that constant.
1230  uint64_t TheRetVal = TargetsForSlot[0].RetVal;
1231  for (const VirtualCallTarget &Target : TargetsForSlot)
1232  if (Target.RetVal != TheRetVal)
1233  return false;
1234 
1235  if (CSInfo.isExported()) {
1237  Res->Info = TheRetVal;
1238  }
1239 
1240  applyUniformRetValOpt(CSInfo, TargetsForSlot[0].Fn->getName(), TheRetVal);
1241  if (RemarksEnabled)
1242  for (auto &&Target : TargetsForSlot)
1243  Target.WasDevirt = true;
1244  return true;
1245 }
1246 
1247 std::string DevirtModule::getGlobalName(VTableSlot Slot,
1248  ArrayRef<uint64_t> Args,
1249  StringRef Name) {
1250  std::string FullName = "__typeid_";
1251  raw_string_ostream OS(FullName);
1252  OS << cast<MDString>(Slot.TypeID)->getString() << '_' << Slot.ByteOffset;
1253  for (uint64_t Arg : Args)
1254  OS << '_' << Arg;
1255  OS << '_' << Name;
1256  return OS.str();
1257 }
1258 
1259 bool DevirtModule::shouldExportConstantsAsAbsoluteSymbols() {
1260  Triple T(M.getTargetTriple());
1261  return (T.getArch() == Triple::x86 || T.getArch() == Triple::x86_64) &&
1262  T.getObjectFormat() == Triple::ELF;
1263 }
1264 
1265 void DevirtModule::exportGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
1266  StringRef Name, Constant *C) {
1268  getGlobalName(Slot, Args, Name), C, &M);
1270 }
1271 
1272 void DevirtModule::exportConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
1273  StringRef Name, uint32_t Const,
1274  uint32_t &Storage) {
1275  if (shouldExportConstantsAsAbsoluteSymbols()) {
1276  exportGlobal(
1277  Slot, Args, Name,
1278  ConstantExpr::getIntToPtr(ConstantInt::get(Int32Ty, Const), Int8PtrTy));
1279  return;
1280  }
1281 
1282  Storage = Const;
1283 }
1284 
1285 Constant *DevirtModule::importGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
1286  StringRef Name) {
1287  Constant *C = M.getOrInsertGlobal(getGlobalName(Slot, Args, Name), Int8Ty);
1288  auto *GV = dyn_cast<GlobalVariable>(C);
1289  if (GV)
1291  return C;
1292 }
1293 
1294 Constant *DevirtModule::importConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
1295  StringRef Name, IntegerType *IntTy,
1296  uint32_t Storage) {
1297  if (!shouldExportConstantsAsAbsoluteSymbols())
1298  return ConstantInt::get(IntTy, Storage);
1299 
1300  Constant *C = importGlobal(Slot, Args, Name);
1301  auto *GV = cast<GlobalVariable>(C->stripPointerCasts());
1302  C = ConstantExpr::getPtrToInt(C, IntTy);
1303 
1304  // We only need to set metadata if the global is newly created, in which
1305  // case it would not have hidden visibility.
1306  if (GV->hasMetadata(LLVMContext::MD_absolute_symbol))
1307  return C;
1308 
1309  auto SetAbsRange = [&](uint64_t Min, uint64_t Max) {
1310  auto *MinC = ConstantAsMetadata::get(ConstantInt::get(IntPtrTy, Min));
1311  auto *MaxC = ConstantAsMetadata::get(ConstantInt::get(IntPtrTy, Max));
1312  GV->setMetadata(LLVMContext::MD_absolute_symbol,
1313  MDNode::get(M.getContext(), {MinC, MaxC}));
1314  };
1315  unsigned AbsWidth = IntTy->getBitWidth();
1316  if (AbsWidth == IntPtrTy->getBitWidth())
1317  SetAbsRange(~0ull, ~0ull); // Full set.
1318  else
1319  SetAbsRange(0, 1ull << AbsWidth);
1320  return C;
1321 }
1322 
1323 void DevirtModule::applyUniqueRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
1324  bool IsOne,
1325  Constant *UniqueMemberAddr) {
1326  for (auto &&Call : CSInfo.CallSites) {
1327  IRBuilder<> B(Call.CS.getInstruction());
1328  Value *Cmp =
1329  B.CreateICmp(IsOne ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
1330  B.CreateBitCast(Call.VTable, Int8PtrTy), UniqueMemberAddr);
1331  Cmp = B.CreateZExt(Cmp, Call.CS->getType());
1332  Call.replaceAndErase("unique-ret-val", FnName, RemarksEnabled, OREGetter,
1333  Cmp);
1334  }
1335  CSInfo.markDevirt();
1336 }
1337 
1338 Constant *DevirtModule::getMemberAddr(const TypeMemberInfo *M) {
1339  Constant *C = ConstantExpr::getBitCast(M->Bits->GV, Int8PtrTy);
1340  return ConstantExpr::getGetElementPtr(Int8Ty, C,
1341  ConstantInt::get(Int64Ty, M->Offset));
1342 }
1343 
1344 bool DevirtModule::tryUniqueRetValOpt(
1345  unsigned BitWidth, MutableArrayRef<VirtualCallTarget> TargetsForSlot,
1346  CallSiteInfo &CSInfo, WholeProgramDevirtResolution::ByArg *Res,
1347  VTableSlot Slot, ArrayRef<uint64_t> Args) {
1348  // IsOne controls whether we look for a 0 or a 1.
1349  auto tryUniqueRetValOptFor = [&](bool IsOne) {
1350  const TypeMemberInfo *UniqueMember = nullptr;
1351  for (const VirtualCallTarget &Target : TargetsForSlot) {
1352  if (Target.RetVal == (IsOne ? 1 : 0)) {
1353  if (UniqueMember)
1354  return false;
1355  UniqueMember = Target.TM;
1356  }
1357  }
1358 
1359  // We should have found a unique member or bailed out by now. We already
1360  // checked for a uniform return value in tryUniformRetValOpt.
1361  assert(UniqueMember);
1362 
1363  Constant *UniqueMemberAddr = getMemberAddr(UniqueMember);
1364  if (CSInfo.isExported()) {
1366  Res->Info = IsOne;
1367 
1368  exportGlobal(Slot, Args, "unique_member", UniqueMemberAddr);
1369  }
1370 
1371  // Replace each call with the comparison.
1372  applyUniqueRetValOpt(CSInfo, TargetsForSlot[0].Fn->getName(), IsOne,
1373  UniqueMemberAddr);
1374 
1375  // Update devirtualization statistics for targets.
1376  if (RemarksEnabled)
1377  for (auto &&Target : TargetsForSlot)
1378  Target.WasDevirt = true;
1379 
1380  return true;
1381  };
1382 
1383  if (BitWidth == 1) {
1384  if (tryUniqueRetValOptFor(true))
1385  return true;
1386  if (tryUniqueRetValOptFor(false))
1387  return true;
1388  }
1389  return false;
1390 }
1391 
1392 void DevirtModule::applyVirtualConstProp(CallSiteInfo &CSInfo, StringRef FnName,
1393  Constant *Byte, Constant *Bit) {
1394  for (auto Call : CSInfo.CallSites) {
1395  auto *RetType = cast<IntegerType>(Call.CS.getType());
1396  IRBuilder<> B(Call.CS.getInstruction());
1397  Value *Addr =
1398  B.CreateGEP(Int8Ty, B.CreateBitCast(Call.VTable, Int8PtrTy), Byte);
1399  if (RetType->getBitWidth() == 1) {
1400  Value *Bits = B.CreateLoad(Int8Ty, Addr);
1401  Value *BitsAndBit = B.CreateAnd(Bits, Bit);
1402  auto IsBitSet = B.CreateICmpNE(BitsAndBit, ConstantInt::get(Int8Ty, 0));
1403  Call.replaceAndErase("virtual-const-prop-1-bit", FnName, RemarksEnabled,
1404  OREGetter, IsBitSet);
1405  } else {
1406  Value *ValAddr = B.CreateBitCast(Addr, RetType->getPointerTo());
1407  Value *Val = B.CreateLoad(RetType, ValAddr);
1408  Call.replaceAndErase("virtual-const-prop", FnName, RemarksEnabled,
1409  OREGetter, Val);
1410  }
1411  }
1412  CSInfo.markDevirt();
1413 }
1414 
1415 bool DevirtModule::tryVirtualConstProp(
1416  MutableArrayRef<VirtualCallTarget> TargetsForSlot, VTableSlotInfo &SlotInfo,
1417  WholeProgramDevirtResolution *Res, VTableSlot Slot) {
1418  // This only works if the function returns an integer.
1419  auto RetType = dyn_cast<IntegerType>(TargetsForSlot[0].Fn->getReturnType());
1420  if (!RetType)
1421  return false;
1422  unsigned BitWidth = RetType->getBitWidth();
1423  if (BitWidth > 64)
1424  return false;
1425 
1426  // Make sure that each function is defined, does not access memory, takes at
1427  // least one argument, does not use its first argument (which we assume is
1428  // 'this'), and has the same return type.
1429  //
1430  // Note that we test whether this copy of the function is readnone, rather
1431  // than testing function attributes, which must hold for any copy of the
1432  // function, even a less optimized version substituted at link time. This is
1433  // sound because the virtual constant propagation optimizations effectively
1434  // inline all implementations of the virtual function into each call site,
1435  // rather than using function attributes to perform local optimization.
1436  for (VirtualCallTarget &Target : TargetsForSlot) {
1437  if (Target.Fn->isDeclaration() ||
1438  computeFunctionBodyMemoryAccess(*Target.Fn, AARGetter(*Target.Fn)) !=
1439  MAK_ReadNone ||
1440  Target.Fn->arg_empty() || !Target.Fn->arg_begin()->use_empty() ||
1441  Target.Fn->getReturnType() != RetType)
1442  return false;
1443  }
1444 
1445  for (auto &&CSByConstantArg : SlotInfo.ConstCSInfo) {
1446  if (!tryEvaluateFunctionsWithArgs(TargetsForSlot, CSByConstantArg.first))
1447  continue;
1448 
1449  WholeProgramDevirtResolution::ByArg *ResByArg = nullptr;
1450  if (Res)
1451  ResByArg = &Res->ResByArg[CSByConstantArg.first];
1452 
1453  if (tryUniformRetValOpt(TargetsForSlot, CSByConstantArg.second, ResByArg))
1454  continue;
1455 
1456  if (tryUniqueRetValOpt(BitWidth, TargetsForSlot, CSByConstantArg.second,
1457  ResByArg, Slot, CSByConstantArg.first))
1458  continue;
1459 
1460  // Find an allocation offset in bits in all vtables associated with the
1461  // type.
1462  uint64_t AllocBefore =
1463  findLowestOffset(TargetsForSlot, /*IsAfter=*/false, BitWidth);
1464  uint64_t AllocAfter =
1465  findLowestOffset(TargetsForSlot, /*IsAfter=*/true, BitWidth);
1466 
1467  // Calculate the total amount of padding needed to store a value at both
1468  // ends of the object.
1469  uint64_t TotalPaddingBefore = 0, TotalPaddingAfter = 0;
1470  for (auto &&Target : TargetsForSlot) {
1471  TotalPaddingBefore += std::max<int64_t>(
1472  (AllocBefore + 7) / 8 - Target.allocatedBeforeBytes() - 1, 0);
1473  TotalPaddingAfter += std::max<int64_t>(
1474  (AllocAfter + 7) / 8 - Target.allocatedAfterBytes() - 1, 0);
1475  }
1476 
1477  // If the amount of padding is too large, give up.
1478  // FIXME: do something smarter here.
1479  if (std::min(TotalPaddingBefore, TotalPaddingAfter) > 128)
1480  continue;
1481 
1482  // Calculate the offset to the value as a (possibly negative) byte offset
1483  // and (if applicable) a bit offset, and store the values in the targets.
1484  int64_t OffsetByte;
1485  uint64_t OffsetBit;
1486  if (TotalPaddingBefore <= TotalPaddingAfter)
1487  setBeforeReturnValues(TargetsForSlot, AllocBefore, BitWidth, OffsetByte,
1488  OffsetBit);
1489  else
1490  setAfterReturnValues(TargetsForSlot, AllocAfter, BitWidth, OffsetByte,
1491  OffsetBit);
1492 
1493  if (RemarksEnabled)
1494  for (auto &&Target : TargetsForSlot)
1495  Target.WasDevirt = true;
1496 
1497 
1498  if (CSByConstantArg.second.isExported()) {
1500  exportConstant(Slot, CSByConstantArg.first, "byte", OffsetByte,
1501  ResByArg->Byte);
1502  exportConstant(Slot, CSByConstantArg.first, "bit", 1ULL << OffsetBit,
1503  ResByArg->Bit);
1504  }
1505 
1506  // Rewrite each call to a load from OffsetByte/OffsetBit.
1507  Constant *ByteConst = ConstantInt::get(Int32Ty, OffsetByte);
1508  Constant *BitConst = ConstantInt::get(Int8Ty, 1ULL << OffsetBit);
1509  applyVirtualConstProp(CSByConstantArg.second,
1510  TargetsForSlot[0].Fn->getName(), ByteConst, BitConst);
1511  }
1512  return true;
1513 }
1514 
1515 void DevirtModule::rebuildGlobal(VTableBits &B) {
1516  if (B.Before.Bytes.empty() && B.After.Bytes.empty())
1517  return;
1518 
1519  // Align the before byte array to the global's minimum alignment so that we
1520  // don't break any alignment requirements on the global.
1521  unsigned Align = B.GV->getAlignment();
1522  if (Align == 0)
1523  Align = M.getDataLayout().getABITypeAlignment(B.GV->getValueType());
1524  B.Before.Bytes.resize(alignTo(B.Before.Bytes.size(), Align));
1525 
1526  // Before was stored in reverse order; flip it now.
1527  for (size_t I = 0, Size = B.Before.Bytes.size(); I != Size / 2; ++I)
1528  std::swap(B.Before.Bytes[I], B.Before.Bytes[Size - 1 - I]);
1529 
1530  // Build an anonymous global containing the before bytes, followed by the
1531  // original initializer, followed by the after bytes.
1532  auto NewInit = ConstantStruct::getAnon(
1533  {ConstantDataArray::get(M.getContext(), B.Before.Bytes),
1534  B.GV->getInitializer(),
1535  ConstantDataArray::get(M.getContext(), B.After.Bytes)});
1536  auto NewGV =
1537  new GlobalVariable(M, NewInit->getType(), B.GV->isConstant(),
1538  GlobalVariable::PrivateLinkage, NewInit, "", B.GV);
1539  NewGV->setSection(B.GV->getSection());
1540  NewGV->setComdat(B.GV->getComdat());
1541  NewGV->setAlignment(B.GV->getAlignment());
1542 
1543  // Copy the original vtable's metadata to the anonymous global, adjusting
1544  // offsets as required.
1545  NewGV->copyMetadata(B.GV, B.Before.Bytes.size());
1546 
1547  // Build an alias named after the original global, pointing at the second
1548  // element (the original initializer).
1549  auto Alias = GlobalAlias::create(
1550  B.GV->getInitializer()->getType(), 0, B.GV->getLinkage(), "",
1552  NewInit->getType(), NewGV,
1554  ConstantInt::get(Int32Ty, 1)}),
1555  &M);
1556  Alias->setVisibility(B.GV->getVisibility());
1557  Alias->takeName(B.GV);
1558 
1559  B.GV->replaceAllUsesWith(Alias);
1560  B.GV->eraseFromParent();
1561 }
1562 
1563 bool DevirtModule::areRemarksEnabled() {
1564  const auto &FL = M.getFunctionList();
1565  for (const Function &Fn : FL) {
1566  const auto &BBL = Fn.getBasicBlockList();
1567  if (BBL.empty())
1568  continue;
1569  auto DI = OptimizationRemark(DEBUG_TYPE, "", DebugLoc(), &BBL.front());
1570  return DI.isEnabled();
1571  }
1572  return false;
1573 }
1574 
1575 void DevirtModule::scanTypeTestUsers(Function *TypeTestFunc,
1576  Function *AssumeFunc) {
1577  // Find all virtual calls via a virtual table pointer %p under an assumption
1578  // of the form llvm.assume(llvm.type.test(%p, %md)). This indicates that %p
1579  // points to a member of the type identifier %md. Group calls by (type ID,
1580  // offset) pair (effectively the identity of the virtual function) and store
1581  // to CallSlots.
1582  DenseSet<CallSite> SeenCallSites;
1583  for (auto I = TypeTestFunc->use_begin(), E = TypeTestFunc->use_end();
1584  I != E;) {
1585  auto CI = dyn_cast<CallInst>(I->getUser());
1586  ++I;
1587  if (!CI)
1588  continue;
1589 
1590  // Search for virtual calls based on %p and add them to DevirtCalls.
1591  SmallVector<DevirtCallSite, 1> DevirtCalls;
1593  auto &DT = LookupDomTree(*CI->getFunction());
1594  findDevirtualizableCallsForTypeTest(DevirtCalls, Assumes, CI, DT);
1595 
1596  // If we found any, add them to CallSlots.
1597  if (!Assumes.empty()) {
1598  Metadata *TypeId =
1599  cast<MetadataAsValue>(CI->getArgOperand(1))->getMetadata();
1600  Value *Ptr = CI->getArgOperand(0)->stripPointerCasts();
1601  for (DevirtCallSite Call : DevirtCalls) {
1602  // Only add this CallSite if we haven't seen it before. The vtable
1603  // pointer may have been CSE'd with pointers from other call sites,
1604  // and we don't want to process call sites multiple times. We can't
1605  // just skip the vtable Ptr if it has been seen before, however, since
1606  // it may be shared by type tests that dominate different calls.
1607  if (SeenCallSites.insert(Call.CS).second)
1608  CallSlots[{TypeId, Call.Offset}].addCallSite(Ptr, Call.CS, nullptr);
1609  }
1610  }
1611 
1612  // We no longer need the assumes or the type test.
1613  for (auto Assume : Assumes)
1614  Assume->eraseFromParent();
1615  // We can't use RecursivelyDeleteTriviallyDeadInstructions here because we
1616  // may use the vtable argument later.
1617  if (CI->use_empty())
1618  CI->eraseFromParent();
1619  }
1620 }
1621 
1622 void DevirtModule::scanTypeCheckedLoadUsers(Function *TypeCheckedLoadFunc) {
1623  Function *TypeTestFunc = Intrinsic::getDeclaration(&M, Intrinsic::type_test);
1624 
1625  for (auto I = TypeCheckedLoadFunc->use_begin(),
1626  E = TypeCheckedLoadFunc->use_end();
1627  I != E;) {
1628  auto CI = dyn_cast<CallInst>(I->getUser());
1629  ++I;
1630  if (!CI)
1631  continue;
1632 
1633  Value *Ptr = CI->getArgOperand(0);
1634  Value *Offset = CI->getArgOperand(1);
1635  Value *TypeIdValue = CI->getArgOperand(2);
1636  Metadata *TypeId = cast<MetadataAsValue>(TypeIdValue)->getMetadata();
1637 
1638  SmallVector<DevirtCallSite, 1> DevirtCalls;
1639  SmallVector<Instruction *, 1> LoadedPtrs;
1641  bool HasNonCallUses = false;
1642  auto &DT = LookupDomTree(*CI->getFunction());
1643  findDevirtualizableCallsForTypeCheckedLoad(DevirtCalls, LoadedPtrs, Preds,
1644  HasNonCallUses, CI, DT);
1645 
1646  // Start by generating "pessimistic" code that explicitly loads the function
1647  // pointer from the vtable and performs the type check. If possible, we will
1648  // eliminate the load and the type check later.
1649 
1650  // If possible, only generate the load at the point where it is used.
1651  // This helps avoid unnecessary spills.
1652  IRBuilder<> LoadB(
1653  (LoadedPtrs.size() == 1 && !HasNonCallUses) ? LoadedPtrs[0] : CI);
1654  Value *GEP = LoadB.CreateGEP(Int8Ty, Ptr, Offset);
1655  Value *GEPPtr = LoadB.CreateBitCast(GEP, PointerType::getUnqual(Int8PtrTy));
1656  Value *LoadedValue = LoadB.CreateLoad(Int8PtrTy, GEPPtr);
1657 
1658  for (Instruction *LoadedPtr : LoadedPtrs) {
1659  LoadedPtr->replaceAllUsesWith(LoadedValue);
1660  LoadedPtr->eraseFromParent();
1661  }
1662 
1663  // Likewise for the type test.
1664  IRBuilder<> CallB((Preds.size() == 1 && !HasNonCallUses) ? Preds[0] : CI);
1665  CallInst *TypeTestCall = CallB.CreateCall(TypeTestFunc, {Ptr, TypeIdValue});
1666 
1667  for (Instruction *Pred : Preds) {
1668  Pred->replaceAllUsesWith(TypeTestCall);
1669  Pred->eraseFromParent();
1670  }
1671 
1672  // We have already erased any extractvalue instructions that refer to the
1673  // intrinsic call, but the intrinsic may have other non-extractvalue uses
1674  // (although this is unlikely). In that case, explicitly build a pair and
1675  // RAUW it.
1676  if (!CI->use_empty()) {
1677  Value *Pair = UndefValue::get(CI->getType());
1678  IRBuilder<> B(CI);
1679  Pair = B.CreateInsertValue(Pair, LoadedValue, {0});
1680  Pair = B.CreateInsertValue(Pair, TypeTestCall, {1});
1681  CI->replaceAllUsesWith(Pair);
1682  }
1683 
1684  // The number of unsafe uses is initially the number of uses.
1685  auto &NumUnsafeUses = NumUnsafeUsesForTypeTest[TypeTestCall];
1686  NumUnsafeUses = DevirtCalls.size();
1687 
1688  // If the function pointer has a non-call user, we cannot eliminate the type
1689  // check, as one of those users may eventually call the pointer. Increment
1690  // the unsafe use count to make sure it cannot reach zero.
1691  if (HasNonCallUses)
1692  ++NumUnsafeUses;
1693  for (DevirtCallSite Call : DevirtCalls) {
1694  CallSlots[{TypeId, Call.Offset}].addCallSite(Ptr, Call.CS,
1695  &NumUnsafeUses);
1696  }
1697 
1698  CI->eraseFromParent();
1699  }
1700 }
1701 
1702 void DevirtModule::importResolution(VTableSlot Slot, VTableSlotInfo &SlotInfo) {
1703  auto *TypeId = dyn_cast<MDString>(Slot.TypeID);
1704  if (!TypeId)
1705  return;
1706  const TypeIdSummary *TidSummary =
1707  ImportSummary->getTypeIdSummary(TypeId->getString());
1708  if (!TidSummary)
1709  return;
1710  auto ResI = TidSummary->WPDRes.find(Slot.ByteOffset);
1711  if (ResI == TidSummary->WPDRes.end())
1712  return;
1713  const WholeProgramDevirtResolution &Res = ResI->second;
1714 
1716  assert(!Res.SingleImplName.empty());
1717  // The type of the function in the declaration is irrelevant because every
1718  // call site will cast it to the correct type.
1719  Constant *SingleImpl =
1720  cast<Constant>(M.getOrInsertFunction(Res.SingleImplName,
1721  Type::getVoidTy(M.getContext()))
1722  .getCallee());
1723 
1724  // This is the import phase so we should not be exporting anything.
1725  bool IsExported = false;
1726  applySingleImplDevirt(SlotInfo, SingleImpl, IsExported);
1727  assert(!IsExported);
1728  }
1729 
1730  for (auto &CSByConstantArg : SlotInfo.ConstCSInfo) {
1731  auto I = Res.ResByArg.find(CSByConstantArg.first);
1732  if (I == Res.ResByArg.end())
1733  continue;
1734  auto &ResByArg = I->second;
1735  // FIXME: We should figure out what to do about the "function name" argument
1736  // to the apply* functions, as the function names are unavailable during the
1737  // importing phase. For now we just pass the empty string. This does not
1738  // impact correctness because the function names are just used for remarks.
1739  switch (ResByArg.TheKind) {
1741  applyUniformRetValOpt(CSByConstantArg.second, "", ResByArg.Info);
1742  break;
1744  Constant *UniqueMemberAddr =
1745  importGlobal(Slot, CSByConstantArg.first, "unique_member");
1746  applyUniqueRetValOpt(CSByConstantArg.second, "", ResByArg.Info,
1747  UniqueMemberAddr);
1748  break;
1749  }
1751  Constant *Byte = importConstant(Slot, CSByConstantArg.first, "byte",
1752  Int32Ty, ResByArg.Byte);
1753  Constant *Bit = importConstant(Slot, CSByConstantArg.first, "bit", Int8Ty,
1754  ResByArg.Bit);
1755  applyVirtualConstProp(CSByConstantArg.second, "", Byte, Bit);
1756  break;
1757  }
1758  default:
1759  break;
1760  }
1761  }
1762 
1764  // The type of the function is irrelevant, because it's bitcast at calls
1765  // anyhow.
1766  Constant *JT = cast<Constant>(
1767  M.getOrInsertFunction(getGlobalName(Slot, {}, "branch_funnel"),
1768  Type::getVoidTy(M.getContext()))
1769  .getCallee());
1770  bool IsExported = false;
1771  applyICallBranchFunnel(SlotInfo, JT, IsExported);
1772  assert(!IsExported);
1773  }
1774 }
1775 
1776 void DevirtModule::removeRedundantTypeTests() {
1777  auto True = ConstantInt::getTrue(M.getContext());
1778  for (auto &&U : NumUnsafeUsesForTypeTest) {
1779  if (U.second == 0) {
1780  U.first->replaceAllUsesWith(True);
1781  U.first->eraseFromParent();
1782  }
1783  }
1784 }
1785 
1786 bool DevirtModule::run() {
1787  // If only some of the modules were split, we cannot correctly perform
1788  // this transformation. We already checked for the presense of type tests
1789  // with partially split modules during the thin link, and would have emitted
1790  // an error if any were found, so here we can simply return.
1791  if ((ExportSummary && ExportSummary->partiallySplitLTOUnits()) ||
1792  (ImportSummary && ImportSummary->partiallySplitLTOUnits()))
1793  return false;
1794 
1795  Function *TypeTestFunc =
1796  M.getFunction(Intrinsic::getName(Intrinsic::type_test));
1797  Function *TypeCheckedLoadFunc =
1798  M.getFunction(Intrinsic::getName(Intrinsic::type_checked_load));
1799  Function *AssumeFunc = M.getFunction(Intrinsic::getName(Intrinsic::assume));
1800 
1801  // Normally if there are no users of the devirtualization intrinsics in the
1802  // module, this pass has nothing to do. But if we are exporting, we also need
1803  // to handle any users that appear only in the function summaries.
1804  if (!ExportSummary &&
1805  (!TypeTestFunc || TypeTestFunc->use_empty() || !AssumeFunc ||
1806  AssumeFunc->use_empty()) &&
1807  (!TypeCheckedLoadFunc || TypeCheckedLoadFunc->use_empty()))
1808  return false;
1809 
1810  if (TypeTestFunc && AssumeFunc)
1811  scanTypeTestUsers(TypeTestFunc, AssumeFunc);
1812 
1813  if (TypeCheckedLoadFunc)
1814  scanTypeCheckedLoadUsers(TypeCheckedLoadFunc);
1815 
1816  if (ImportSummary) {
1817  for (auto &S : CallSlots)
1818  importResolution(S.first, S.second);
1819 
1820  removeRedundantTypeTests();
1821 
1822  // The rest of the code is only necessary when exporting or during regular
1823  // LTO, so we are done.
1824  return true;
1825  }
1826 
1827  // Rebuild type metadata into a map for easy lookup.
1828  std::vector<VTableBits> Bits;
1830  buildTypeIdentifierMap(Bits, TypeIdMap);
1831  if (TypeIdMap.empty())
1832  return true;
1833 
1834  // Collect information from summary about which calls to try to devirtualize.
1835  if (ExportSummary) {
1837  for (auto &P : TypeIdMap) {
1838  if (auto *TypeId = dyn_cast<MDString>(P.first))
1839  MetadataByGUID[GlobalValue::getGUID(TypeId->getString())].push_back(
1840  TypeId);
1841  }
1842 
1843  for (auto &P : *ExportSummary) {
1844  for (auto &S : P.second.SummaryList) {
1845  auto *FS = dyn_cast<FunctionSummary>(S.get());
1846  if (!FS)
1847  continue;
1848  // FIXME: Only add live functions.
1849  for (FunctionSummary::VFuncId VF : FS->type_test_assume_vcalls()) {
1850  for (Metadata *MD : MetadataByGUID[VF.GUID]) {
1851  CallSlots[{MD, VF.Offset}]
1852  .CSInfo.markSummaryHasTypeTestAssumeUsers();
1853  }
1854  }
1855  for (FunctionSummary::VFuncId VF : FS->type_checked_load_vcalls()) {
1856  for (Metadata *MD : MetadataByGUID[VF.GUID]) {
1857  CallSlots[{MD, VF.Offset}].CSInfo.addSummaryTypeCheckedLoadUser(FS);
1858  }
1859  }
1860  for (const FunctionSummary::ConstVCall &VC :
1861  FS->type_test_assume_const_vcalls()) {
1862  for (Metadata *MD : MetadataByGUID[VC.VFunc.GUID]) {
1863  CallSlots[{MD, VC.VFunc.Offset}]
1864  .ConstCSInfo[VC.Args]
1865  .markSummaryHasTypeTestAssumeUsers();
1866  }
1867  }
1868  for (const FunctionSummary::ConstVCall &VC :
1869  FS->type_checked_load_const_vcalls()) {
1870  for (Metadata *MD : MetadataByGUID[VC.VFunc.GUID]) {
1871  CallSlots[{MD, VC.VFunc.Offset}]
1872  .ConstCSInfo[VC.Args]
1873  .addSummaryTypeCheckedLoadUser(FS);
1874  }
1875  }
1876  }
1877  }
1878  }
1879 
1880  // For each (type, offset) pair:
1881  bool DidVirtualConstProp = false;
1882  std::map<std::string, Function*> DevirtTargets;
1883  for (auto &S : CallSlots) {
1884  // Search each of the members of the type identifier for the virtual
1885  // function implementation at offset S.first.ByteOffset, and add to
1886  // TargetsForSlot.
1887  std::vector<VirtualCallTarget> TargetsForSlot;
1888  if (tryFindVirtualCallTargets(TargetsForSlot, TypeIdMap[S.first.TypeID],
1889  S.first.ByteOffset)) {
1890  WholeProgramDevirtResolution *Res = nullptr;
1891  if (ExportSummary && isa<MDString>(S.first.TypeID))
1892  Res = &ExportSummary
1893  ->getOrInsertTypeIdSummary(
1894  cast<MDString>(S.first.TypeID)->getString())
1895  .WPDRes[S.first.ByteOffset];
1896 
1897  if (!trySingleImplDevirt(TargetsForSlot, S.second, Res)) {
1898  DidVirtualConstProp |=
1899  tryVirtualConstProp(TargetsForSlot, S.second, Res, S.first);
1900 
1901  tryICallBranchFunnel(TargetsForSlot, S.second, Res, S.first);
1902  }
1903 
1904  // Collect functions devirtualized at least for one call site for stats.
1905  if (RemarksEnabled)
1906  for (const auto &T : TargetsForSlot)
1907  if (T.WasDevirt)
1908  DevirtTargets[T.Fn->getName()] = T.Fn;
1909  }
1910 
1911  // CFI-specific: if we are exporting and any llvm.type.checked.load
1912  // intrinsics were *not* devirtualized, we need to add the resulting
1913  // llvm.type.test intrinsics to the function summaries so that the
1914  // LowerTypeTests pass will export them.
1915  if (ExportSummary && isa<MDString>(S.first.TypeID)) {
1916  auto GUID =
1917  GlobalValue::getGUID(cast<MDString>(S.first.TypeID)->getString());
1918  for (auto FS : S.second.CSInfo.SummaryTypeCheckedLoadUsers)
1919  FS->addTypeTest(GUID);
1920  for (auto &CCS : S.second.ConstCSInfo)
1921  for (auto FS : CCS.second.SummaryTypeCheckedLoadUsers)
1922  FS->addTypeTest(GUID);
1923  }
1924  }
1925 
1926  if (RemarksEnabled) {
1927  // Generate remarks for each devirtualized function.
1928  for (const auto &DT : DevirtTargets) {
1929  Function *F = DT.second;
1930 
1931  using namespace ore;
1932  OREGetter(F).emit(OptimizationRemark(DEBUG_TYPE, "Devirtualized", F)
1933  << "devirtualized "
1934  << NV("FunctionName", DT.first));
1935  }
1936  }
1937 
1938  removeRedundantTypeTests();
1939 
1940  // Rebuild each global we touched as part of virtual constant propagation to
1941  // include the before and after bytes.
1942  if (DidVirtualConstProp)
1943  for (VTableBits &B : Bits)
1944  rebuildGlobal(B);
1945 
1946  return true;
1947 }
1948 
1949 void DevirtIndex::run() {
1950  if (ExportSummary.typeIdCompatibleVtableMap().empty())
1951  return;
1952 
1954  for (auto &P : ExportSummary.typeIdCompatibleVtableMap()) {
1955  NameByGUID[GlobalValue::getGUID(P.first)].push_back(P.first);
1956  }
1957 
1958  // Collect information from summary about which calls to try to devirtualize.
1959  for (auto &P : ExportSummary) {
1960  for (auto &S : P.second.SummaryList) {
1961  auto *FS = dyn_cast<FunctionSummary>(S.get());
1962  if (!FS)
1963  continue;
1964  // FIXME: Only add live functions.
1965  for (FunctionSummary::VFuncId VF : FS->type_test_assume_vcalls()) {
1966  for (StringRef Name : NameByGUID[VF.GUID]) {
1967  CallSlots[{Name, VF.Offset}].CSInfo.addSummaryTypeTestAssumeUser(FS);
1968  }
1969  }
1970  for (FunctionSummary::VFuncId VF : FS->type_checked_load_vcalls()) {
1971  for (StringRef Name : NameByGUID[VF.GUID]) {
1972  CallSlots[{Name, VF.Offset}].CSInfo.addSummaryTypeCheckedLoadUser(FS);
1973  }
1974  }
1975  for (const FunctionSummary::ConstVCall &VC :
1976  FS->type_test_assume_const_vcalls()) {
1977  for (StringRef Name : NameByGUID[VC.VFunc.GUID]) {
1978  CallSlots[{Name, VC.VFunc.Offset}]
1979  .ConstCSInfo[VC.Args]
1980  .addSummaryTypeTestAssumeUser(FS);
1981  }
1982  }
1983  for (const FunctionSummary::ConstVCall &VC :
1984  FS->type_checked_load_const_vcalls()) {
1985  for (StringRef Name : NameByGUID[VC.VFunc.GUID]) {
1986  CallSlots[{Name, VC.VFunc.Offset}]
1987  .ConstCSInfo[VC.Args]
1988  .addSummaryTypeCheckedLoadUser(FS);
1989  }
1990  }
1991  }
1992  }
1993 
1994  std::set<ValueInfo> DevirtTargets;
1995  // For each (type, offset) pair:
1996  for (auto &S : CallSlots) {
1997  // Search each of the members of the type identifier for the virtual
1998  // function implementation at offset S.first.ByteOffset, and add to
1999  // TargetsForSlot.
2000  std::vector<ValueInfo> TargetsForSlot;
2001  auto TidSummary = ExportSummary.getTypeIdCompatibleVtableSummary(S.first.TypeID);
2002  assert(TidSummary);
2003  if (tryFindVirtualCallTargets(TargetsForSlot, *TidSummary,
2004  S.first.ByteOffset)) {
2006  &ExportSummary.getOrInsertTypeIdSummary(S.first.TypeID)
2007  .WPDRes[S.first.ByteOffset];
2008 
2009  if (!trySingleImplDevirt(TargetsForSlot, S.first, S.second, Res,
2010  DevirtTargets))
2011  continue;
2012  }
2013  }
2014 
2015  // Optionally have the thin link print message for each devirtualized
2016  // function.
2017  if (PrintSummaryDevirt)
2018  for (const auto &DT : DevirtTargets)
2019  errs() << "Devirtualized call to " << DT << "\n";
2020 
2021  return;
2022 }
void setVisibility(VisibilityTypes V)
Definition: GlobalValue.h:242
IterTy arg_end() const
Definition: CallSite.h:588
uint64_t CallInst * C
StringRef getSection() const
Get the custom section of this global if it has one.
Definition: GlobalObject.h:94
unsigned getAlignment() const
Definition: GlobalObject.h:59
use_iterator use_end()
Definition: Value.h:366
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:111
constexpr char Align[]
Key for Kernel::Arg::Metadata::mAlign.
const std::string & getTargetTriple() const
Get the target triple which is a string describing the target host.
Definition: Module.h:240
std::vector< TypeIdOffsetVtableInfo > TypeIdCompatibleVtableInfo
List of vtable definitions decorated by a particular type identifier, and their corresponding offsets...
bool empty() const
Definition: Function.h:686
raw_ostream & errs()
This returns a reference to a raw_ostream for standard error.
bool hasLocalLinkage() const
Definition: GlobalValue.h:445
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
GCNRegPressure max(const GCNRegPressure &P1, const GCNRegPressure &P2)
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:776
const Constant * getInitializer() const
getInitializer - Return the initializer for this global variable.
IterTy arg_begin() const
Definition: CallSite.h:584
This class represents lattice values for constants.
Definition: AllocatorList.h:23
void setAttributes(AttributeList PAL)
Set the parameter attributes of the call.
Definition: CallSite.h:341
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:1576
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:65
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:1153
amdgpu Simplify well known AMD library false FunctionCallee Value const Twine & Name
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)
VirtualCallTarget(Function *Fn, const TypeMemberInfo *TM)
Implements a dense probed hash-table based set.
Definition: DenseSet.h:249
const StructLayout * getStructLayout(StructType *Ty) const
Returns a StructLayout object, indicating the alignment of the struct, its size, and the offsets of i...
Definition: DataLayout.cpp:618
void push_back(const T &Elt)
Definition: SmallVector.h:211
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
Helper for check-and-exit error handling.
Definition: Error.h:1273
void initializeWholeProgramDevirtPass(PassRegistry &)
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:104
static Constant * getIntToPtr(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1791
uint64_t Info
Additional information for the resolution:
Like Internal, but omit from symbol table.
Definition: GlobalValue.h:56
iterator find(StringRef Key)
Definition: StringMap.h:332
void setCallingConv(CallingConv::ID CC)
Set the calling convention of the call.
Definition: CallSite.h:324
Externally visible function.
Definition: GlobalValue.h:48
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
bool all_of(R &&range, UnaryPredicate P)
Provide wrappers to std::all_of which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1165
A debug info location.
Definition: DebugLoc.h:33
Metadata node.
Definition: Metadata.h:863
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:230
F(f)
const GlobalListType & getGlobalList() const
Get the Module&#39;s list of global variables (constant).
Definition: Module.h:524
static IntegerType * getInt64Ty(LLVMContext &C)
Definition: Type.cpp:176
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...
unsigned getElementContainingOffset(uint64_t Offset) const
Given a valid byte offset into the structure, returns the structure index that contains it...
Definition: DataLayout.cpp:79
FunctionType * getFunctionType() const
Definition: CallSite.h:328
static bool isLocalLinkage(LinkageTypes Linkage)
Definition: GlobalValue.h:330
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:289
CallingConv::ID getCallingConv() const
Get the calling convention of the call.
Definition: CallSite.h:320
Export information to summary.
const char * getName() const
getName - Get the target name.
iterator_range< global_object_iterator > global_objects()
Definition: Module.h:662
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:119
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...
AnalysisUsage & addRequired()
Used to lazily calculate structure layout information for a target machine, based on the DataLayout s...
Definition: DataLayout.h:559
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:50
StringRef getName(ID id)
Return the LLVM name for an intrinsic, such as "llvm.ppc.altivec.lvx".
Definition: Function.cpp:639
const DataLayout & getDataLayout() const
Get the data layout for the module&#39;s target platform.
Definition: Module.cpp:369
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:244
The returned value is undefined.
Definition: MathExtras.h:45
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)
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:779
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...
TypeID
Definitions of all of the base types for the Type system.
Definition: Type.h:54
No attributes have been set.
Definition: Attributes.h:72
AttributeSet getRetAttributes() const
The attributes for the ret value are returned.
unsigned Intr
void setName(const Twine &Name)
Change the name of the value.
Definition: Value.cpp:285
Type * getType() const
Return the type of the instruction that generated this call site.
Definition: CallSite.h:272
static bool isLinkOnceODRLinkage(LinkageTypes Linkage)
Definition: GlobalValue.h:306
static bool isEqual(const VTableSlot &LHS, const VTableSlot &RHS)
enum llvm::WholeProgramDevirtResolution::Kind TheKind
InstrTy * getInstruction() const
Definition: CallSite.h:96
Class to represent function types.
Definition: DerivedTypes.h:103
Value * CreateBitCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1964
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
Class to represent array types.
Definition: DerivedTypes.h:403
AttributeSet getParamAttributes(unsigned ArgNo) const
The attributes for the argument or parameter at the given index are returned.
bool isVarArg() const
Definition: DerivedTypes.h:123
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:460
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:429
constexpr char Attrs[]
Key for Kernel::Metadata::mAttrs.
unsigned getBitWidth() const
Get the number of bits in this IntegerType.
Definition: DerivedTypes.h:66
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:409
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
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:1079
The file should be opened in text mode on platforms that make this distinction.
Definition: FileSystem.h:767
Value * getOperand(unsigned i) const
Definition: User.h:169
Class to represent pointers.
Definition: DerivedTypes.h:570
static PreservedAnalyses none()
Convenience factory function for the empty preserved set.
Definition: PassManager.h:156
static Constant * getBitCast(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1804
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:774
static MDTuple * get(LLVMContext &Context, ArrayRef< Metadata *> MDs)
Definition: Metadata.h:1165
#define P(N)
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:432
bool hasAttribute(AttrKind Val) const
Return true if the attribute is present.
Definition: Attributes.cpp:238
static Function * Create(FunctionType *Ty, LinkageTypes Linkage, unsigned AddrSpace, const Twine &N="", Module *M=nullptr)
Definition: Function.h:135
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:153
* if(!EatIfPresent(lltok::kw_thread_local)) return false
ParseOptionalThreadLocal := /*empty.
static AttributeSet get(LLVMContext &C, const AttrBuilder &B)
Definition: Attributes.cpp:592
VisibilityTypes getVisibility() const
Definition: GlobalValue.h:236
MutableArrayRef - Represent a mutable reference to an array (0 or more elements consecutively in memo...
Definition: ArrayRef.h:290
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.
unsigned getNumArgOperands() const
Definition: CallSite.h:303
Import information from summary.
LLVM Basic Block Representation.
Definition: BasicBlock.h:57
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
static bool isWeakODRLinkage(LinkageTypes Linkage)
Definition: GlobalValue.h:315
A call site that could be devirtualized.
static Optional< bool > isBigEndian(const SmallVector< int64_t, 4 > &ByteOffsets, int64_t FirstOffset)
size_t size() const
size - Get the array size.
Definition: ArrayRef.h:148
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:652
PreservedAnalyses run(Module &M, ModuleAnalysisManager &)
This file contains the declarations for the subclasses of Constant, which represent the different fla...
bool isPointerTy() const
True if this is an instance of PointerType.
Definition: Type.h:223
#define DEBUG_TYPE
AttributeList getAttributes() const
Get the parameter attributes of the call.
Definition: CallSite.h:337
A manager for alias analyses.
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:384
INITIALIZE_PASS_BEGIN(WholeProgramDevirt, "wholeprogramdevirt", "Whole program devirtualization", false, false) INITIALIZE_PASS_END(WholeProgramDevirt
ArrayRef< Type * > params() const
Definition: DerivedTypes.h:130
Expected< T > errorOrToExpected(ErrorOr< T > &&EO)
Convert an ErrorOr<T> to an Expected<T>.
Definition: Error.h:1117
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:380
static Type * getVoidTy(LLVMContext &C)
Definition: Type.cpp:160
Type::TypeID TypeID
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:296
static BasicBlock * Create(LLVMContext &Context, const Twine &Name="", Function *Parent=nullptr, BasicBlock *InsertBefore=nullptr)
Creates a new BasicBlock.
Definition: BasicBlock.h:99
void reserve(size_type NumEntries)
Grow the densemap so that it can contain at least NumEntries items before resizing again...
Definition: DenseMap.h:103
const ModuleHash & getModuleHash(const StringRef ModPath) const
Get the module SHA1 hash recorded for the given module path.
LLVM_NODISCARD bool contains(StringRef Other) const
Return true if the given string is a substring of *this, and false otherwise.
Definition: StringRef.h:446
Class to represent integer types.
Definition: DerivedTypes.h:40
enum llvm::WholeProgramDevirtResolution::ByArg::Kind TheKind
static UndefValue * get(Type *T)
Static factory methods - Return an &#39;undef&#39; object of the specified type.
Definition: Constants.cpp:1446
const Constant * stripPointerCasts() const
Definition: Constant.h:183
Comdat * getOrInsertComdat(StringRef Name)
Return the Comdat in the module with the specified name.
Definition: Module.cpp:482
const Value * stripPointerCasts() const
Strip off pointer casts, all-zero GEPs and address space casts.
Definition: Value.cpp:525
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:159
size_t size() const
Definition: SmallVector.h:52
static PointerType * getInt8PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:219
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:519
INITIALIZE_PASS_END(RegBankSelect, DEBUG_TYPE, "Assign register bank of generic virtual registers", false, false) RegBankSelect
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:40
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:43
An "identifier" for a virtual function.
bool arg_empty() const
Definition: CallSite.h:225
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 * CreateGEP(Value *Ptr, ArrayRef< Value *> IdxList, const Twine &Name="")
Definition: IRBuilder.h:1677
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
unsigned getNumOperands() const
Definition: User.h:191
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:585
This is the shared class of boolean and integer constants.
Definition: Constants.h:83
void setSelectionKind(SelectionKind Val)
Definition: Comdat.h:45
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
Module.h This file contains the declarations for the Module class.
Single implementation devirtualization.
void updateIndexWPDForExports(ModuleSummaryIndex &Summary, StringMap< FunctionImporter::ExportSetTy > &ExportLists, std::map< ValueInfo, std::vector< VTableSlotSummary >> &LocalWPDTargetsMap)
Call after cross-module importing to update the recorded single impl devirt target names for any loca...
Type * getReturnType() const
Definition: DerivedTypes.h:124
uint64_t getSizeInBytes() const
Definition: DataLayout.h:567
unsigned getProgramAddressSpace() const
Definition: DataLayout.h:283
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:653
static BranchInst * Create(BasicBlock *IfTrue, Instruction *InsertBefore=nullptr)
static ConstantInt * getTrue(LLVMContext &Context)
Definition: Constants.cpp:609
void setLinkage(LinkageTypes LT)
Definition: GlobalValue.h:454
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:940
StringMap - This is an unconventional map that is specialized for handling keys that are "strings"...
Definition: StringMap.h:219
wholeprogramdevirt
Target - Wrapper for Target specific information.
unsigned getNumAttrSets() const
A specification for a virtual function call with all constant integer arguments.
BBTy * getParent() const
Get the basic block containing the call site.
Definition: CallSite.h:101
GUID getGUID() const
Return a 64-bit global unique ID constructed from global value name (i.e.
Definition: GlobalValue.h:510
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:178
#define clEnumValN(ENUMVAL, FLAGNAME, DESC)
Definition: CommandLine.h:627
const Comdat * getComdat() const
Definition: GlobalObject.h:105
ModulePass * createWholeProgramDevirtPass(ModuleSummaryIndex *ExportSummary, const ModuleSummaryIndex *ImportSummary)
This pass implements whole-program devirtualization using type metadata.
uint64_t getTypeAllocSize(Type *Ty) const
Returns the offset in bytes between successive objects of the specified type, including alignment pad...
Definition: DataLayout.h:470
use_iterator use_begin()
Definition: Value.h:358
uint64_t alignTo(uint64_t Size, Align A)
Returns a multiple of A needed to store Size bytes.
Definition: Alignment.h:133
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
A raw_ostream that writes to a file descriptor.
Definition: raw_ostream.h:384
uint64_t getElementOffset(unsigned Idx) const
Definition: DataLayout.h:581
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:175
uint64_t findLowestOffset(ArrayRef< VirtualCallTarget > Targets, bool IsAfter, uint64_t Size)
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:55
StringRef getValueAsString() const
Return the attribute&#39;s value as a string.
Definition: Attributes.cpp:223
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:214
static Constant * getPtrToInt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1778
#define I(x, y, z)
Definition: MD5.cpp:58
ModulePass class - This class is used to implement unstructured interprocedural optimizations and ana...
Definition: Pass.h:224
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:332
Type * getValueType() const
Definition: GlobalValue.h:279
const BasicBlockListType & getBasicBlockList() const
Get the underlying elements of the Function...
Definition: Function.h:657
uint32_t Size
Definition: Profile.cpp:46
Rename collisions when linking (static functions).
Definition: GlobalValue.h:55
CallInst * CreateCall(FunctionType *FTy, Value *Callee, ArrayRef< Value *> Args=None, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:2237
static Attribute get(LLVMContext &Context, AttrKind Kind, uint64_t Val=0)
Return a uniquified Attribute object.
Definition: Attributes.cpp:80
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.
bool isCall() const
Return true if a CallInst is enclosed.
Definition: CallSite.h:87
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:503
aarch64 promote const
LLVM Value Representation.
Definition: Value.h:73
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:333
static Constant * getAnon(ArrayRef< Constant *> V, bool Packed=false)
Return an anonymous struct that has the specified elements.
Definition: Constants.h:468
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:702
Type * getElementType() const
Definition: DerivedTypes.h:394
iterator_range< global_iterator > globals()
Definition: Module.h:587
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
This is the interface for LLVM&#39;s primary stateless and local alias analysis.
A single uniqued string.
Definition: Metadata.h:603
static cl::opt< std::string > ClReadSummary("wholeprogramdevirt-read-summary", cl::desc("Read summary from given YAML file before running pass"), cl::Hidden)
static cl::opt< std::string > ClWriteSummary("wholeprogramdevirt-write-summary", cl::desc("Write summary to given YAML file after running pass"), cl::Hidden)
A container for analyses that lazily runs them and caches their results.
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:259
Root of the metadata hierarchy.
Definition: Metadata.h:57
static IntegerType * getInt8Ty(LLVMContext &C)
Definition: Type.cpp:173
void setSection(StringRef S)
Change the section for this global.
Definition: Globals.cpp:215
The optimization diagnostic interface.
static unsigned getHashValue(const VTableSlotSummary &I)
bool use_empty() const
Definition: Value.h:342
iterator end()
Definition: StringMap.h:317
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:485
constexpr char Args[]
Key for Kernel::Metadata::mArgs.
The following data structures summarize type metadata information.
ValTy * getArgOperand(unsigned i) const
Definition: CallSite.h:307
static AttributeList get(LLVMContext &C, ArrayRef< std::pair< unsigned, Attribute >> Attrs)
Create an AttributeList with the specified parameters in it.
Definition: Attributes.cpp:973
IntegerType * Int32Ty
An analysis over an "outer" IR unit that provides access to an analysis manager over an "inner" IR un...
Definition: PassManager.h:1044
FunTy * getCaller() const
Return the caller function for this call site.
Definition: CallSite.h:275