Bug Summary

File:llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
Warning:line 1251, column 18
Access to field 'TheKind' results in a dereference of a null pointer (loaded from variable 'Res')

Annotated Source Code

Press '?' to see keyboard shortcuts

clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name WholeProgramDevirt.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -fno-split-dwarf-inlining -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-12/lib/clang/12.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/build-llvm/lib/Transforms/IPO -I /build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO -I /build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/build-llvm/include -I /build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-12/lib/clang/12.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/build-llvm/lib/Transforms/IPO -fdebug-prefix-map=/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2020-10-27-053609-25509-1 -x c++ /build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp

/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp

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
53#include "llvm/Transforms/IPO/WholeProgramDevirt.h"
54#include "llvm/ADT/ArrayRef.h"
55#include "llvm/ADT/DenseMap.h"
56#include "llvm/ADT/DenseMapInfo.h"
57#include "llvm/ADT/DenseSet.h"
58#include "llvm/ADT/MapVector.h"
59#include "llvm/ADT/SmallVector.h"
60#include "llvm/ADT/Triple.h"
61#include "llvm/ADT/iterator_range.h"
62#include "llvm/Analysis/AliasAnalysis.h"
63#include "llvm/Analysis/BasicAliasAnalysis.h"
64#include "llvm/Analysis/OptimizationRemarkEmitter.h"
65#include "llvm/Analysis/TypeMetadataUtils.h"
66#include "llvm/Bitcode/BitcodeReader.h"
67#include "llvm/Bitcode/BitcodeWriter.h"
68#include "llvm/IR/Constants.h"
69#include "llvm/IR/DataLayout.h"
70#include "llvm/IR/DebugLoc.h"
71#include "llvm/IR/DerivedTypes.h"
72#include "llvm/IR/Dominators.h"
73#include "llvm/IR/Function.h"
74#include "llvm/IR/GlobalAlias.h"
75#include "llvm/IR/GlobalVariable.h"
76#include "llvm/IR/IRBuilder.h"
77#include "llvm/IR/InstrTypes.h"
78#include "llvm/IR/Instruction.h"
79#include "llvm/IR/Instructions.h"
80#include "llvm/IR/Intrinsics.h"
81#include "llvm/IR/LLVMContext.h"
82#include "llvm/IR/Metadata.h"
83#include "llvm/IR/Module.h"
84#include "llvm/IR/ModuleSummaryIndexYAML.h"
85#include "llvm/InitializePasses.h"
86#include "llvm/Pass.h"
87#include "llvm/PassRegistry.h"
88#include "llvm/Support/Casting.h"
89#include "llvm/Support/CommandLine.h"
90#include "llvm/Support/Errc.h"
91#include "llvm/Support/Error.h"
92#include "llvm/Support/FileSystem.h"
93#include "llvm/Support/GlobPattern.h"
94#include "llvm/Support/MathExtras.h"
95#include "llvm/Transforms/IPO.h"
96#include "llvm/Transforms/IPO/FunctionAttrs.h"
97#include "llvm/Transforms/Utils/Evaluator.h"
98#include <algorithm>
99#include <cstddef>
100#include <map>
101#include <set>
102#include <string>
103
104using namespace llvm;
105using namespace wholeprogramdevirt;
106
107#define DEBUG_TYPE"wholeprogramdevirt" "wholeprogramdevirt"
108
109static cl::opt<PassSummaryAction> ClSummaryAction(
110 "wholeprogramdevirt-summary-action",
111 cl::desc("What to do with the summary when running this pass"),
112 cl::values(clEnumValN(PassSummaryAction::None, "none", "Do nothing")llvm::cl::OptionEnumValue { "none", int(PassSummaryAction::None
), "Do nothing" }
,
113 clEnumValN(PassSummaryAction::Import, "import",llvm::cl::OptionEnumValue { "import", int(PassSummaryAction::
Import), "Import typeid resolutions from summary and globals"
}
114 "Import typeid resolutions from summary and globals")llvm::cl::OptionEnumValue { "import", int(PassSummaryAction::
Import), "Import typeid resolutions from summary and globals"
}
,
115 clEnumValN(PassSummaryAction::Export, "export",llvm::cl::OptionEnumValue { "export", int(PassSummaryAction::
Export), "Export typeid resolutions to summary and globals" }
116 "Export typeid resolutions to summary and globals")llvm::cl::OptionEnumValue { "export", int(PassSummaryAction::
Export), "Export typeid resolutions to summary and globals" }
),
117 cl::Hidden);
118
119static cl::opt<std::string> ClReadSummary(
120 "wholeprogramdevirt-read-summary",
121 cl::desc(
122 "Read summary from given bitcode or YAML file before running pass"),
123 cl::Hidden);
124
125static cl::opt<std::string> ClWriteSummary(
126 "wholeprogramdevirt-write-summary",
127 cl::desc("Write summary to given bitcode or YAML file after running pass. "
128 "Output file format is deduced from extension: *.bc means writing "
129 "bitcode, otherwise YAML"),
130 cl::Hidden);
131
132static cl::opt<unsigned>
133 ClThreshold("wholeprogramdevirt-branch-funnel-threshold", cl::Hidden,
134 cl::init(10), cl::ZeroOrMore,
135 cl::desc("Maximum number of call targets per "
136 "call site to enable branch funnels"));
137
138static cl::opt<bool>
139 PrintSummaryDevirt("wholeprogramdevirt-print-index-based", cl::Hidden,
140 cl::init(false), cl::ZeroOrMore,
141 cl::desc("Print index-based devirtualization messages"));
142
143/// Provide a way to force enable whole program visibility in tests.
144/// This is needed to support legacy tests that don't contain
145/// !vcall_visibility metadata (the mere presense of type tests
146/// previously implied hidden visibility).
147cl::opt<bool>
148 WholeProgramVisibility("whole-program-visibility", cl::init(false),
149 cl::Hidden, cl::ZeroOrMore,
150 cl::desc("Enable whole program visibility"));
151
152/// Provide a way to force disable whole program for debugging or workarounds,
153/// when enabled via the linker.
154cl::opt<bool> DisableWholeProgramVisibility(
155 "disable-whole-program-visibility", cl::init(false), cl::Hidden,
156 cl::ZeroOrMore,
157 cl::desc("Disable whole program visibility (overrides enabling options)"));
158
159/// Provide way to prevent certain function from being devirtualized
160cl::list<std::string>
161 SkipFunctionNames("wholeprogramdevirt-skip",
162 cl::desc("Prevent function(s) from being devirtualized"),
163 cl::Hidden, cl::ZeroOrMore, cl::CommaSeparated);
164
165namespace {
166struct PatternList {
167 std::vector<GlobPattern> Patterns;
168 template <class T> void init(const T &StringList) {
169 for (const auto &S : StringList)
170 if (Expected<GlobPattern> Pat = GlobPattern::create(S))
171 Patterns.push_back(std::move(*Pat));
172 }
173 bool match(StringRef S) {
174 for (const GlobPattern &P : Patterns)
175 if (P.match(S))
176 return true;
177 return false;
178 }
179};
180} // namespace
181
182// Find the minimum offset that we may store a value of size Size bits at. If
183// IsAfter is set, look for an offset before the object, otherwise look for an
184// offset after the object.
185uint64_t
186wholeprogramdevirt::findLowestOffset(ArrayRef<VirtualCallTarget> Targets,
187 bool IsAfter, uint64_t Size) {
188 // Find a minimum offset taking into account only vtable sizes.
189 uint64_t MinByte = 0;
190 for (const VirtualCallTarget &Target : Targets) {
191 if (IsAfter)
192 MinByte = std::max(MinByte, Target.minAfterBytes());
193 else
194 MinByte = std::max(MinByte, Target.minBeforeBytes());
195 }
196
197 // Build a vector of arrays of bytes covering, for each target, a slice of the
198 // used region (see AccumBitVector::BytesUsed in
199 // llvm/Transforms/IPO/WholeProgramDevirt.h) starting at MinByte. Effectively,
200 // this aligns the used regions to start at MinByte.
201 //
202 // In this example, A, B and C are vtables, # is a byte already allocated for
203 // a virtual function pointer, AAAA... (etc.) are the used regions for the
204 // vtables and Offset(X) is the value computed for the Offset variable below
205 // for X.
206 //
207 // Offset(A)
208 // | |
209 // |MinByte
210 // A: ################AAAAAAAA|AAAAAAAA
211 // B: ########BBBBBBBBBBBBBBBB|BBBB
212 // C: ########################|CCCCCCCCCCCCCCCC
213 // | Offset(B) |
214 //
215 // This code produces the slices of A, B and C that appear after the divider
216 // at MinByte.
217 std::vector<ArrayRef<uint8_t>> Used;
218 for (const VirtualCallTarget &Target : Targets) {
219 ArrayRef<uint8_t> VTUsed = IsAfter ? Target.TM->Bits->After.BytesUsed
220 : Target.TM->Bits->Before.BytesUsed;
221 uint64_t Offset = IsAfter ? MinByte - Target.minAfterBytes()
222 : MinByte - Target.minBeforeBytes();
223
224 // Disregard used regions that are smaller than Offset. These are
225 // effectively all-free regions that do not need to be checked.
226 if (VTUsed.size() > Offset)
227 Used.push_back(VTUsed.slice(Offset));
228 }
229
230 if (Size == 1) {
231 // Find a free bit in each member of Used.
232 for (unsigned I = 0;; ++I) {
233 uint8_t BitsUsed = 0;
234 for (auto &&B : Used)
235 if (I < B.size())
236 BitsUsed |= B[I];
237 if (BitsUsed != 0xff)
238 return (MinByte + I) * 8 +
239 countTrailingZeros(uint8_t(~BitsUsed), ZB_Undefined);
240 }
241 } else {
242 // Find a free (Size/8) byte region in each member of Used.
243 // FIXME: see if alignment helps.
244 for (unsigned I = 0;; ++I) {
245 for (auto &&B : Used) {
246 unsigned Byte = 0;
247 while ((I + Byte) < B.size() && Byte < (Size / 8)) {
248 if (B[I + Byte])
249 goto NextI;
250 ++Byte;
251 }
252 }
253 return (MinByte + I) * 8;
254 NextI:;
255 }
256 }
257}
258
259void wholeprogramdevirt::setBeforeReturnValues(
260 MutableArrayRef<VirtualCallTarget> Targets, uint64_t AllocBefore,
261 unsigned BitWidth, int64_t &OffsetByte, uint64_t &OffsetBit) {
262 if (BitWidth == 1)
263 OffsetByte = -(AllocBefore / 8 + 1);
264 else
265 OffsetByte = -((AllocBefore + 7) / 8 + (BitWidth + 7) / 8);
266 OffsetBit = AllocBefore % 8;
267
268 for (VirtualCallTarget &Target : Targets) {
269 if (BitWidth == 1)
270 Target.setBeforeBit(AllocBefore);
271 else
272 Target.setBeforeBytes(AllocBefore, (BitWidth + 7) / 8);
273 }
274}
275
276void wholeprogramdevirt::setAfterReturnValues(
277 MutableArrayRef<VirtualCallTarget> Targets, uint64_t AllocAfter,
278 unsigned BitWidth, int64_t &OffsetByte, uint64_t &OffsetBit) {
279 if (BitWidth == 1)
280 OffsetByte = AllocAfter / 8;
281 else
282 OffsetByte = (AllocAfter + 7) / 8;
283 OffsetBit = AllocAfter % 8;
284
285 for (VirtualCallTarget &Target : Targets) {
286 if (BitWidth == 1)
287 Target.setAfterBit(AllocAfter);
288 else
289 Target.setAfterBytes(AllocAfter, (BitWidth + 7) / 8);
290 }
291}
292
293VirtualCallTarget::VirtualCallTarget(Function *Fn, const TypeMemberInfo *TM)
294 : Fn(Fn), TM(TM),
295 IsBigEndian(Fn->getParent()->getDataLayout().isBigEndian()), WasDevirt(false) {}
296
297namespace {
298
299// A slot in a set of virtual tables. The TypeID identifies the set of virtual
300// tables, and the ByteOffset is the offset in bytes from the address point to
301// the virtual function pointer.
302struct VTableSlot {
303 Metadata *TypeID;
304 uint64_t ByteOffset;
305};
306
307} // end anonymous namespace
308
309namespace llvm {
310
311template <> struct DenseMapInfo<VTableSlot> {
312 static VTableSlot getEmptyKey() {
313 return {DenseMapInfo<Metadata *>::getEmptyKey(),
314 DenseMapInfo<uint64_t>::getEmptyKey()};
315 }
316 static VTableSlot getTombstoneKey() {
317 return {DenseMapInfo<Metadata *>::getTombstoneKey(),
318 DenseMapInfo<uint64_t>::getTombstoneKey()};
319 }
320 static unsigned getHashValue(const VTableSlot &I) {
321 return DenseMapInfo<Metadata *>::getHashValue(I.TypeID) ^
322 DenseMapInfo<uint64_t>::getHashValue(I.ByteOffset);
323 }
324 static bool isEqual(const VTableSlot &LHS,
325 const VTableSlot &RHS) {
326 return LHS.TypeID == RHS.TypeID && LHS.ByteOffset == RHS.ByteOffset;
327 }
328};
329
330template <> struct DenseMapInfo<VTableSlotSummary> {
331 static VTableSlotSummary getEmptyKey() {
332 return {DenseMapInfo<StringRef>::getEmptyKey(),
333 DenseMapInfo<uint64_t>::getEmptyKey()};
334 }
335 static VTableSlotSummary getTombstoneKey() {
336 return {DenseMapInfo<StringRef>::getTombstoneKey(),
337 DenseMapInfo<uint64_t>::getTombstoneKey()};
338 }
339 static unsigned getHashValue(const VTableSlotSummary &I) {
340 return DenseMapInfo<StringRef>::getHashValue(I.TypeID) ^
341 DenseMapInfo<uint64_t>::getHashValue(I.ByteOffset);
342 }
343 static bool isEqual(const VTableSlotSummary &LHS,
344 const VTableSlotSummary &RHS) {
345 return LHS.TypeID == RHS.TypeID && LHS.ByteOffset == RHS.ByteOffset;
346 }
347};
348
349} // end namespace llvm
350
351namespace {
352
353// A virtual call site. VTable is the loaded virtual table pointer, and CS is
354// the indirect virtual call.
355struct VirtualCallSite {
356 Value *VTable = nullptr;
357 CallBase &CB;
358
359 // If non-null, this field points to the associated unsafe use count stored in
360 // the DevirtModule::NumUnsafeUsesForTypeTest map below. See the description
361 // of that field for details.
362 unsigned *NumUnsafeUses = nullptr;
363
364 void
365 emitRemark(const StringRef OptName, const StringRef TargetName,
366 function_ref<OptimizationRemarkEmitter &(Function *)> OREGetter) {
367 Function *F = CB.getCaller();
368 DebugLoc DLoc = CB.getDebugLoc();
369 BasicBlock *Block = CB.getParent();
370
371 using namespace ore;
372 OREGetter(F).emit(OptimizationRemark(DEBUG_TYPE"wholeprogramdevirt", OptName, DLoc, Block)
373 << NV("Optimization", OptName)
374 << ": devirtualized a call to "
375 << NV("FunctionName", TargetName));
376 }
377
378 void replaceAndErase(
379 const StringRef OptName, const StringRef TargetName, bool RemarksEnabled,
380 function_ref<OptimizationRemarkEmitter &(Function *)> OREGetter,
381 Value *New) {
382 if (RemarksEnabled)
383 emitRemark(OptName, TargetName, OREGetter);
384 CB.replaceAllUsesWith(New);
385 if (auto *II = dyn_cast<InvokeInst>(&CB)) {
386 BranchInst::Create(II->getNormalDest(), &CB);
387 II->getUnwindDest()->removePredecessor(II->getParent());
388 }
389 CB.eraseFromParent();
390 // This use is no longer unsafe.
391 if (NumUnsafeUses)
392 --*NumUnsafeUses;
393 }
394};
395
396// Call site information collected for a specific VTableSlot and possibly a list
397// of constant integer arguments. The grouping by arguments is handled by the
398// VTableSlotInfo class.
399struct CallSiteInfo {
400 /// The set of call sites for this slot. Used during regular LTO and the
401 /// import phase of ThinLTO (as well as the export phase of ThinLTO for any
402 /// call sites that appear in the merged module itself); in each of these
403 /// cases we are directly operating on the call sites at the IR level.
404 std::vector<VirtualCallSite> CallSites;
405
406 /// Whether all call sites represented by this CallSiteInfo, including those
407 /// in summaries, have been devirtualized. This starts off as true because a
408 /// default constructed CallSiteInfo represents no call sites.
409 bool AllCallSitesDevirted = true;
410
411 // These fields are used during the export phase of ThinLTO and reflect
412 // information collected from function summaries.
413
414 /// Whether any function summary contains an llvm.assume(llvm.type.test) for
415 /// this slot.
416 bool SummaryHasTypeTestAssumeUsers = false;
417
418 /// CFI-specific: a vector containing the list of function summaries that use
419 /// the llvm.type.checked.load intrinsic and therefore will require
420 /// resolutions for llvm.type.test in order to implement CFI checks if
421 /// devirtualization was unsuccessful. If devirtualization was successful, the
422 /// pass will clear this vector by calling markDevirt(). If at the end of the
423 /// pass the vector is non-empty, we will need to add a use of llvm.type.test
424 /// to each of the function summaries in the vector.
425 std::vector<FunctionSummary *> SummaryTypeCheckedLoadUsers;
426 std::vector<FunctionSummary *> SummaryTypeTestAssumeUsers;
427
428 bool isExported() const {
429 return SummaryHasTypeTestAssumeUsers ||
61
Assuming field 'SummaryHasTypeTestAssumeUsers' is true
62
Returning the value 1, which participates in a condition later
430 !SummaryTypeCheckedLoadUsers.empty();
431 }
432
433 void addSummaryTypeCheckedLoadUser(FunctionSummary *FS) {
434 SummaryTypeCheckedLoadUsers.push_back(FS);
435 AllCallSitesDevirted = false;
436 }
437
438 void addSummaryTypeTestAssumeUser(FunctionSummary *FS) {
439 SummaryTypeTestAssumeUsers.push_back(FS);
440 SummaryHasTypeTestAssumeUsers = true;
441 AllCallSitesDevirted = false;
442 }
443
444 void markDevirt() {
445 AllCallSitesDevirted = true;
446
447 // As explained in the comment for SummaryTypeCheckedLoadUsers.
448 SummaryTypeCheckedLoadUsers.clear();
449 }
450};
451
452// Call site information collected for a specific VTableSlot.
453struct VTableSlotInfo {
454 // The set of call sites which do not have all constant integer arguments
455 // (excluding "this").
456 CallSiteInfo CSInfo;
457
458 // The set of call sites with all constant integer arguments (excluding
459 // "this"), grouped by argument list.
460 std::map<std::vector<uint64_t>, CallSiteInfo> ConstCSInfo;
461
462 void addCallSite(Value *VTable, CallBase &CB, unsigned *NumUnsafeUses);
463
464private:
465 CallSiteInfo &findCallSiteInfo(CallBase &CB);
466};
467
468CallSiteInfo &VTableSlotInfo::findCallSiteInfo(CallBase &CB) {
469 std::vector<uint64_t> Args;
470 auto *CBType = dyn_cast<IntegerType>(CB.getType());
471 if (!CBType || CBType->getBitWidth() > 64 || CB.arg_empty())
472 return CSInfo;
473 for (auto &&Arg : make_range(CB.arg_begin() + 1, CB.arg_end())) {
474 auto *CI = dyn_cast<ConstantInt>(Arg);
475 if (!CI || CI->getBitWidth() > 64)
476 return CSInfo;
477 Args.push_back(CI->getZExtValue());
478 }
479 return ConstCSInfo[Args];
480}
481
482void VTableSlotInfo::addCallSite(Value *VTable, CallBase &CB,
483 unsigned *NumUnsafeUses) {
484 auto &CSI = findCallSiteInfo(CB);
485 CSI.AllCallSitesDevirted = false;
486 CSI.CallSites.push_back({VTable, CB, NumUnsafeUses});
487}
488
489struct DevirtModule {
490 Module &M;
491 function_ref<AAResults &(Function &)> AARGetter;
492 function_ref<DominatorTree &(Function &)> LookupDomTree;
493
494 ModuleSummaryIndex *ExportSummary;
495 const ModuleSummaryIndex *ImportSummary;
496
497 IntegerType *Int8Ty;
498 PointerType *Int8PtrTy;
499 IntegerType *Int32Ty;
500 IntegerType *Int64Ty;
501 IntegerType *IntPtrTy;
502 /// Sizeless array type, used for imported vtables. This provides a signal
503 /// to analyzers that these imports may alias, as they do for example
504 /// when multiple unique return values occur in the same vtable.
505 ArrayType *Int8Arr0Ty;
506
507 bool RemarksEnabled;
508 function_ref<OptimizationRemarkEmitter &(Function *)> OREGetter;
509
510 MapVector<VTableSlot, VTableSlotInfo> CallSlots;
511
512 // This map keeps track of the number of "unsafe" uses of a loaded function
513 // pointer. The key is the associated llvm.type.test intrinsic call generated
514 // by this pass. An unsafe use is one that calls the loaded function pointer
515 // directly. Every time we eliminate an unsafe use (for example, by
516 // devirtualizing it or by applying virtual constant propagation), we
517 // decrement the value stored in this map. If a value reaches zero, we can
518 // eliminate the type check by RAUWing the associated llvm.type.test call with
519 // true.
520 std::map<CallInst *, unsigned> NumUnsafeUsesForTypeTest;
521 PatternList FunctionsToSkip;
522
523 DevirtModule(Module &M, function_ref<AAResults &(Function &)> AARGetter,
524 function_ref<OptimizationRemarkEmitter &(Function *)> OREGetter,
525 function_ref<DominatorTree &(Function &)> LookupDomTree,
526 ModuleSummaryIndex *ExportSummary,
527 const ModuleSummaryIndex *ImportSummary)
528 : M(M), AARGetter(AARGetter), LookupDomTree(LookupDomTree),
529 ExportSummary(ExportSummary), ImportSummary(ImportSummary),
530 Int8Ty(Type::getInt8Ty(M.getContext())),
531 Int8PtrTy(Type::getInt8PtrTy(M.getContext())),
532 Int32Ty(Type::getInt32Ty(M.getContext())),
533 Int64Ty(Type::getInt64Ty(M.getContext())),
534 IntPtrTy(M.getDataLayout().getIntPtrType(M.getContext(), 0)),
535 Int8Arr0Ty(ArrayType::get(Type::getInt8Ty(M.getContext()), 0)),
536 RemarksEnabled(areRemarksEnabled()), OREGetter(OREGetter) {
537 assert(!(ExportSummary && ImportSummary))((!(ExportSummary && ImportSummary)) ? static_cast<
void> (0) : __assert_fail ("!(ExportSummary && ImportSummary)"
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 537, __PRETTY_FUNCTION__))
;
538 FunctionsToSkip.init(SkipFunctionNames);
539 }
540
541 bool areRemarksEnabled();
542
543 void
544 scanTypeTestUsers(Function *TypeTestFunc,
545 DenseMap<Metadata *, std::set<TypeMemberInfo>> &TypeIdMap);
546 void scanTypeCheckedLoadUsers(Function *TypeCheckedLoadFunc);
547
548 void buildTypeIdentifierMap(
549 std::vector<VTableBits> &Bits,
550 DenseMap<Metadata *, std::set<TypeMemberInfo>> &TypeIdMap);
551 bool
552 tryFindVirtualCallTargets(std::vector<VirtualCallTarget> &TargetsForSlot,
553 const std::set<TypeMemberInfo> &TypeMemberInfos,
554 uint64_t ByteOffset);
555
556 void applySingleImplDevirt(VTableSlotInfo &SlotInfo, Constant *TheFn,
557 bool &IsExported);
558 bool trySingleImplDevirt(ModuleSummaryIndex *ExportSummary,
559 MutableArrayRef<VirtualCallTarget> TargetsForSlot,
560 VTableSlotInfo &SlotInfo,
561 WholeProgramDevirtResolution *Res);
562
563 void applyICallBranchFunnel(VTableSlotInfo &SlotInfo, Constant *JT,
564 bool &IsExported);
565 void tryICallBranchFunnel(MutableArrayRef<VirtualCallTarget> TargetsForSlot,
566 VTableSlotInfo &SlotInfo,
567 WholeProgramDevirtResolution *Res, VTableSlot Slot);
568
569 bool tryEvaluateFunctionsWithArgs(
570 MutableArrayRef<VirtualCallTarget> TargetsForSlot,
571 ArrayRef<uint64_t> Args);
572
573 void applyUniformRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
574 uint64_t TheRetVal);
575 bool tryUniformRetValOpt(MutableArrayRef<VirtualCallTarget> TargetsForSlot,
576 CallSiteInfo &CSInfo,
577 WholeProgramDevirtResolution::ByArg *Res);
578
579 // Returns the global symbol name that is used to export information about the
580 // given vtable slot and list of arguments.
581 std::string getGlobalName(VTableSlot Slot, ArrayRef<uint64_t> Args,
582 StringRef Name);
583
584 bool shouldExportConstantsAsAbsoluteSymbols();
585
586 // This function is called during the export phase to create a symbol
587 // definition containing information about the given vtable slot and list of
588 // arguments.
589 void exportGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args, StringRef Name,
590 Constant *C);
591 void exportConstant(VTableSlot Slot, ArrayRef<uint64_t> Args, StringRef Name,
592 uint32_t Const, uint32_t &Storage);
593
594 // This function is called during the import phase to create a reference to
595 // the symbol definition created during the export phase.
596 Constant *importGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
597 StringRef Name);
598 Constant *importConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
599 StringRef Name, IntegerType *IntTy,
600 uint32_t Storage);
601
602 Constant *getMemberAddr(const TypeMemberInfo *M);
603
604 void applyUniqueRetValOpt(CallSiteInfo &CSInfo, StringRef FnName, bool IsOne,
605 Constant *UniqueMemberAddr);
606 bool tryUniqueRetValOpt(unsigned BitWidth,
607 MutableArrayRef<VirtualCallTarget> TargetsForSlot,
608 CallSiteInfo &CSInfo,
609 WholeProgramDevirtResolution::ByArg *Res,
610 VTableSlot Slot, ArrayRef<uint64_t> Args);
611
612 void applyVirtualConstProp(CallSiteInfo &CSInfo, StringRef FnName,
613 Constant *Byte, Constant *Bit);
614 bool tryVirtualConstProp(MutableArrayRef<VirtualCallTarget> TargetsForSlot,
615 VTableSlotInfo &SlotInfo,
616 WholeProgramDevirtResolution *Res, VTableSlot Slot);
617
618 void rebuildGlobal(VTableBits &B);
619
620 // Apply the summary resolution for Slot to all virtual calls in SlotInfo.
621 void importResolution(VTableSlot Slot, VTableSlotInfo &SlotInfo);
622
623 // If we were able to eliminate all unsafe uses for a type checked load,
624 // eliminate the associated type tests by replacing them with true.
625 void removeRedundantTypeTests();
626
627 bool run();
628
629 // Lower the module using the action and summary passed as command line
630 // arguments. For testing purposes only.
631 static bool
632 runForTesting(Module &M, function_ref<AAResults &(Function &)> AARGetter,
633 function_ref<OptimizationRemarkEmitter &(Function *)> OREGetter,
634 function_ref<DominatorTree &(Function &)> LookupDomTree);
635};
636
637struct DevirtIndex {
638 ModuleSummaryIndex &ExportSummary;
639 // The set in which to record GUIDs exported from their module by
640 // devirtualization, used by client to ensure they are not internalized.
641 std::set<GlobalValue::GUID> &ExportedGUIDs;
642 // A map in which to record the information necessary to locate the WPD
643 // resolution for local targets in case they are exported by cross module
644 // importing.
645 std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap;
646
647 MapVector<VTableSlotSummary, VTableSlotInfo> CallSlots;
648
649 PatternList FunctionsToSkip;
650
651 DevirtIndex(
652 ModuleSummaryIndex &ExportSummary,
653 std::set<GlobalValue::GUID> &ExportedGUIDs,
654 std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap)
655 : ExportSummary(ExportSummary), ExportedGUIDs(ExportedGUIDs),
656 LocalWPDTargetsMap(LocalWPDTargetsMap) {
657 FunctionsToSkip.init(SkipFunctionNames);
658 }
659
660 bool tryFindVirtualCallTargets(std::vector<ValueInfo> &TargetsForSlot,
661 const TypeIdCompatibleVtableInfo TIdInfo,
662 uint64_t ByteOffset);
663
664 bool trySingleImplDevirt(MutableArrayRef<ValueInfo> TargetsForSlot,
665 VTableSlotSummary &SlotSummary,
666 VTableSlotInfo &SlotInfo,
667 WholeProgramDevirtResolution *Res,
668 std::set<ValueInfo> &DevirtTargets);
669
670 void run();
671};
672
673struct WholeProgramDevirt : public ModulePass {
674 static char ID;
675
676 bool UseCommandLine = false;
677
678 ModuleSummaryIndex *ExportSummary = nullptr;
679 const ModuleSummaryIndex *ImportSummary = nullptr;
680
681 WholeProgramDevirt() : ModulePass(ID), UseCommandLine(true) {
682 initializeWholeProgramDevirtPass(*PassRegistry::getPassRegistry());
683 }
684
685 WholeProgramDevirt(ModuleSummaryIndex *ExportSummary,
686 const ModuleSummaryIndex *ImportSummary)
687 : ModulePass(ID), ExportSummary(ExportSummary),
688 ImportSummary(ImportSummary) {
689 initializeWholeProgramDevirtPass(*PassRegistry::getPassRegistry());
690 }
691
692 bool runOnModule(Module &M) override {
693 if (skipModule(M))
694 return false;
695
696 // In the new pass manager, we can request the optimization
697 // remark emitter pass on a per-function-basis, which the
698 // OREGetter will do for us.
699 // In the old pass manager, this is harder, so we just build
700 // an optimization remark emitter on the fly, when we need it.
701 std::unique_ptr<OptimizationRemarkEmitter> ORE;
702 auto OREGetter = [&](Function *F) -> OptimizationRemarkEmitter & {
703 ORE = std::make_unique<OptimizationRemarkEmitter>(F);
704 return *ORE;
705 };
706
707 auto LookupDomTree = [this](Function &F) -> DominatorTree & {
708 return this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
709 };
710
711 if (UseCommandLine)
712 return DevirtModule::runForTesting(M, LegacyAARGetter(*this), OREGetter,
713 LookupDomTree);
714
715 return DevirtModule(M, LegacyAARGetter(*this), OREGetter, LookupDomTree,
716 ExportSummary, ImportSummary)
717 .run();
718 }
719
720 void getAnalysisUsage(AnalysisUsage &AU) const override {
721 AU.addRequired<AssumptionCacheTracker>();
722 AU.addRequired<TargetLibraryInfoWrapperPass>();
723 AU.addRequired<DominatorTreeWrapperPass>();
724 }
725};
726
727} // end anonymous namespace
728
729INITIALIZE_PASS_BEGIN(WholeProgramDevirt, "wholeprogramdevirt",static void *initializeWholeProgramDevirtPassOnce(PassRegistry
&Registry) {
730 "Whole program devirtualization", false, false)static void *initializeWholeProgramDevirtPassOnce(PassRegistry
&Registry) {
731INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
732INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
733INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
734INITIALIZE_PASS_END(WholeProgramDevirt, "wholeprogramdevirt",PassInfo *PI = new PassInfo( "Whole program devirtualization"
, "wholeprogramdevirt", &WholeProgramDevirt::ID, PassInfo
::NormalCtor_t(callDefaultCtor<WholeProgramDevirt>), false
, false); Registry.registerPass(*PI, true); return PI; } static
llvm::once_flag InitializeWholeProgramDevirtPassFlag; void llvm
::initializeWholeProgramDevirtPass(PassRegistry &Registry
) { llvm::call_once(InitializeWholeProgramDevirtPassFlag, initializeWholeProgramDevirtPassOnce
, std::ref(Registry)); }
735 "Whole program devirtualization", false, false)PassInfo *PI = new PassInfo( "Whole program devirtualization"
, "wholeprogramdevirt", &WholeProgramDevirt::ID, PassInfo
::NormalCtor_t(callDefaultCtor<WholeProgramDevirt>), false
, false); Registry.registerPass(*PI, true); return PI; } static
llvm::once_flag InitializeWholeProgramDevirtPassFlag; void llvm
::initializeWholeProgramDevirtPass(PassRegistry &Registry
) { llvm::call_once(InitializeWholeProgramDevirtPassFlag, initializeWholeProgramDevirtPassOnce
, std::ref(Registry)); }
736char WholeProgramDevirt::ID = 0;
737
738ModulePass *
739llvm::createWholeProgramDevirtPass(ModuleSummaryIndex *ExportSummary,
740 const ModuleSummaryIndex *ImportSummary) {
741 return new WholeProgramDevirt(ExportSummary, ImportSummary);
742}
743
744PreservedAnalyses WholeProgramDevirtPass::run(Module &M,
745 ModuleAnalysisManager &AM) {
746 auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
747 auto AARGetter = [&](Function &F) -> AAResults & {
748 return FAM.getResult<AAManager>(F);
749 };
750 auto OREGetter = [&](Function *F) -> OptimizationRemarkEmitter & {
751 return FAM.getResult<OptimizationRemarkEmitterAnalysis>(*F);
752 };
753 auto LookupDomTree = [&FAM](Function &F) -> DominatorTree & {
754 return FAM.getResult<DominatorTreeAnalysis>(F);
755 };
756 if (UseCommandLine) {
757 if (DevirtModule::runForTesting(M, AARGetter, OREGetter, LookupDomTree))
758 return PreservedAnalyses::all();
759 return PreservedAnalyses::none();
760 }
761 if (!DevirtModule(M, AARGetter, OREGetter, LookupDomTree, ExportSummary,
762 ImportSummary)
763 .run())
764 return PreservedAnalyses::all();
765 return PreservedAnalyses::none();
766}
767
768// Enable whole program visibility if enabled by client (e.g. linker) or
769// internal option, and not force disabled.
770static bool hasWholeProgramVisibility(bool WholeProgramVisibilityEnabledInLTO) {
771 return (WholeProgramVisibilityEnabledInLTO || WholeProgramVisibility) &&
772 !DisableWholeProgramVisibility;
773}
774
775namespace llvm {
776
777/// If whole program visibility asserted, then upgrade all public vcall
778/// visibility metadata on vtable definitions to linkage unit visibility in
779/// Module IR (for regular or hybrid LTO).
780void updateVCallVisibilityInModule(Module &M,
781 bool WholeProgramVisibilityEnabledInLTO) {
782 if (!hasWholeProgramVisibility(WholeProgramVisibilityEnabledInLTO))
783 return;
784 for (GlobalVariable &GV : M.globals())
785 // Add linkage unit visibility to any variable with type metadata, which are
786 // the vtable definitions. We won't have an existing vcall_visibility
787 // metadata on vtable definitions with public visibility.
788 if (GV.hasMetadata(LLVMContext::MD_type) &&
789 GV.getVCallVisibility() == GlobalObject::VCallVisibilityPublic)
790 GV.setVCallVisibilityMetadata(GlobalObject::VCallVisibilityLinkageUnit);
791}
792
793/// If whole program visibility asserted, then upgrade all public vcall
794/// visibility metadata on vtable definition summaries to linkage unit
795/// visibility in Module summary index (for ThinLTO).
796void updateVCallVisibilityInIndex(ModuleSummaryIndex &Index,
797 bool WholeProgramVisibilityEnabledInLTO) {
798 if (!hasWholeProgramVisibility(WholeProgramVisibilityEnabledInLTO))
799 return;
800 for (auto &P : Index) {
801 for (auto &S : P.second.SummaryList) {
802 auto *GVar = dyn_cast<GlobalVarSummary>(S.get());
803 if (!GVar || GVar->vTableFuncs().empty() ||
804 GVar->getVCallVisibility() != GlobalObject::VCallVisibilityPublic)
805 continue;
806 GVar->setVCallVisibility(GlobalObject::VCallVisibilityLinkageUnit);
807 }
808 }
809}
810
811void runWholeProgramDevirtOnIndex(
812 ModuleSummaryIndex &Summary, std::set<GlobalValue::GUID> &ExportedGUIDs,
813 std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap) {
814 DevirtIndex(Summary, ExportedGUIDs, LocalWPDTargetsMap).run();
815}
816
817void updateIndexWPDForExports(
818 ModuleSummaryIndex &Summary,
819 function_ref<bool(StringRef, ValueInfo)> isExported,
820 std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap) {
821 for (auto &T : LocalWPDTargetsMap) {
822 auto &VI = T.first;
823 // This was enforced earlier during trySingleImplDevirt.
824 assert(VI.getSummaryList().size() == 1 &&((VI.getSummaryList().size() == 1 && "Devirt of local target has more than one copy"
) ? static_cast<void> (0) : __assert_fail ("VI.getSummaryList().size() == 1 && \"Devirt of local target has more than one copy\""
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 825, __PRETTY_FUNCTION__))
825 "Devirt of local target has more than one copy")((VI.getSummaryList().size() == 1 && "Devirt of local target has more than one copy"
) ? static_cast<void> (0) : __assert_fail ("VI.getSummaryList().size() == 1 && \"Devirt of local target has more than one copy\""
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 825, __PRETTY_FUNCTION__))
;
826 auto &S = VI.getSummaryList()[0];
827 if (!isExported(S->modulePath(), VI))
828 continue;
829
830 // It's been exported by a cross module import.
831 for (auto &SlotSummary : T.second) {
832 auto *TIdSum = Summary.getTypeIdSummary(SlotSummary.TypeID);
833 assert(TIdSum)((TIdSum) ? static_cast<void> (0) : __assert_fail ("TIdSum"
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 833, __PRETTY_FUNCTION__))
;
834 auto WPDRes = TIdSum->WPDRes.find(SlotSummary.ByteOffset);
835 assert(WPDRes != TIdSum->WPDRes.end())((WPDRes != TIdSum->WPDRes.end()) ? static_cast<void>
(0) : __assert_fail ("WPDRes != TIdSum->WPDRes.end()", "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 835, __PRETTY_FUNCTION__))
;
836 WPDRes->second.SingleImplName = ModuleSummaryIndex::getGlobalNameForLocal(
837 WPDRes->second.SingleImplName,
838 Summary.getModuleHash(S->modulePath()));
839 }
840 }
841}
842
843} // end namespace llvm
844
845static Error checkCombinedSummaryForTesting(ModuleSummaryIndex *Summary) {
846 // Check that summary index contains regular LTO module when performing
847 // export to prevent occasional use of index from pure ThinLTO compilation
848 // (-fno-split-lto-module). This kind of summary index is passed to
849 // DevirtIndex::run, not to DevirtModule::run used by opt/runForTesting.
850 const auto &ModPaths = Summary->modulePaths();
851 if (ClSummaryAction != PassSummaryAction::Import &&
852 ModPaths.find(ModuleSummaryIndex::getRegularLTOModuleName()) ==
853 ModPaths.end())
854 return createStringError(
855 errc::invalid_argument,
856 "combined summary should contain Regular LTO module");
857 return ErrorSuccess();
858}
859
860bool DevirtModule::runForTesting(
861 Module &M, function_ref<AAResults &(Function &)> AARGetter,
862 function_ref<OptimizationRemarkEmitter &(Function *)> OREGetter,
863 function_ref<DominatorTree &(Function &)> LookupDomTree) {
864 std::unique_ptr<ModuleSummaryIndex> Summary =
865 std::make_unique<ModuleSummaryIndex>(/*HaveGVs=*/false);
866
867 // Handle the command-line summary arguments. This code is for testing
868 // purposes only, so we handle errors directly.
869 if (!ClReadSummary.empty()) {
870 ExitOnError ExitOnErr("-wholeprogramdevirt-read-summary: " + ClReadSummary +
871 ": ");
872 auto ReadSummaryFile =
873 ExitOnErr(errorOrToExpected(MemoryBuffer::getFile(ClReadSummary)));
874 if (Expected<std::unique_ptr<ModuleSummaryIndex>> SummaryOrErr =
875 getModuleSummaryIndex(*ReadSummaryFile)) {
876 Summary = std::move(*SummaryOrErr);
877 ExitOnErr(checkCombinedSummaryForTesting(Summary.get()));
878 } else {
879 // Try YAML if we've failed with bitcode.
880 consumeError(SummaryOrErr.takeError());
881 yaml::Input In(ReadSummaryFile->getBuffer());
882 In >> *Summary;
883 ExitOnErr(errorCodeToError(In.error()));
884 }
885 }
886
887 bool Changed =
888 DevirtModule(M, AARGetter, OREGetter, LookupDomTree,
889 ClSummaryAction == PassSummaryAction::Export ? Summary.get()
890 : nullptr,
891 ClSummaryAction == PassSummaryAction::Import ? Summary.get()
892 : nullptr)
893 .run();
894
895 if (!ClWriteSummary.empty()) {
896 ExitOnError ExitOnErr(
897 "-wholeprogramdevirt-write-summary: " + ClWriteSummary + ": ");
898 std::error_code EC;
899 if (StringRef(ClWriteSummary).endswith(".bc")) {
900 raw_fd_ostream OS(ClWriteSummary, EC, sys::fs::OF_None);
901 ExitOnErr(errorCodeToError(EC));
902 WriteIndexToFile(*Summary, OS);
903 } else {
904 raw_fd_ostream OS(ClWriteSummary, EC, sys::fs::OF_Text);
905 ExitOnErr(errorCodeToError(EC));
906 yaml::Output Out(OS);
907 Out << *Summary;
908 }
909 }
910
911 return Changed;
912}
913
914void DevirtModule::buildTypeIdentifierMap(
915 std::vector<VTableBits> &Bits,
916 DenseMap<Metadata *, std::set<TypeMemberInfo>> &TypeIdMap) {
917 DenseMap<GlobalVariable *, VTableBits *> GVToBits;
918 Bits.reserve(M.getGlobalList().size());
919 SmallVector<MDNode *, 2> Types;
920 for (GlobalVariable &GV : M.globals()) {
921 Types.clear();
922 GV.getMetadata(LLVMContext::MD_type, Types);
923 if (GV.isDeclaration() || Types.empty())
924 continue;
925
926 VTableBits *&BitsPtr = GVToBits[&GV];
927 if (!BitsPtr) {
928 Bits.emplace_back();
929 Bits.back().GV = &GV;
930 Bits.back().ObjectSize =
931 M.getDataLayout().getTypeAllocSize(GV.getInitializer()->getType());
932 BitsPtr = &Bits.back();
933 }
934
935 for (MDNode *Type : Types) {
936 auto TypeID = Type->getOperand(1).get();
937
938 uint64_t Offset =
939 cast<ConstantInt>(
940 cast<ConstantAsMetadata>(Type->getOperand(0))->getValue())
941 ->getZExtValue();
942
943 TypeIdMap[TypeID].insert({BitsPtr, Offset});
944 }
945 }
946}
947
948bool DevirtModule::tryFindVirtualCallTargets(
949 std::vector<VirtualCallTarget> &TargetsForSlot,
950 const std::set<TypeMemberInfo> &TypeMemberInfos, uint64_t ByteOffset) {
951 for (const TypeMemberInfo &TM : TypeMemberInfos) {
952 if (!TM.Bits->GV->isConstant())
953 return false;
954
955 // We cannot perform whole program devirtualization analysis on a vtable
956 // with public LTO visibility.
957 if (TM.Bits->GV->getVCallVisibility() ==
958 GlobalObject::VCallVisibilityPublic)
959 return false;
960
961 Constant *Ptr = getPointerAtOffset(TM.Bits->GV->getInitializer(),
962 TM.Offset + ByteOffset, M);
963 if (!Ptr)
964 return false;
965
966 auto Fn = dyn_cast<Function>(Ptr->stripPointerCasts());
967 if (!Fn)
968 return false;
969
970 if (FunctionsToSkip.match(Fn->getName()))
971 return false;
972
973 // We can disregard __cxa_pure_virtual as a possible call target, as
974 // calls to pure virtuals are UB.
975 if (Fn->getName() == "__cxa_pure_virtual")
976 continue;
977
978 TargetsForSlot.push_back({Fn, &TM});
979 }
980
981 // Give up if we couldn't find any targets.
982 return !TargetsForSlot.empty();
23
Assuming the condition is true
24
Returning the value 1, which participates in a condition later
983}
984
985bool DevirtIndex::tryFindVirtualCallTargets(
986 std::vector<ValueInfo> &TargetsForSlot, const TypeIdCompatibleVtableInfo TIdInfo,
987 uint64_t ByteOffset) {
988 for (const TypeIdOffsetVtableInfo &P : TIdInfo) {
989 // Find the first non-available_externally linkage vtable initializer.
990 // We can have multiple available_externally, linkonce_odr and weak_odr
991 // vtable initializers, however we want to skip available_externally as they
992 // do not have type metadata attached, and therefore the summary will not
993 // contain any vtable functions. We can also have multiple external
994 // vtable initializers in the case of comdats, which we cannot check here.
995 // The linker should give an error in this case.
996 //
997 // Also, handle the case of same-named local Vtables with the same path
998 // and therefore the same GUID. This can happen if there isn't enough
999 // distinguishing path when compiling the source file. In that case we
1000 // conservatively return false early.
1001 const GlobalVarSummary *VS = nullptr;
1002 bool LocalFound = false;
1003 for (auto &S : P.VTableVI.getSummaryList()) {
1004 if (GlobalValue::isLocalLinkage(S->linkage())) {
1005 if (LocalFound)
1006 return false;
1007 LocalFound = true;
1008 }
1009 if (!GlobalValue::isAvailableExternallyLinkage(S->linkage())) {
1010 VS = cast<GlobalVarSummary>(S->getBaseObject());
1011 // We cannot perform whole program devirtualization analysis on a vtable
1012 // with public LTO visibility.
1013 if (VS->getVCallVisibility() == GlobalObject::VCallVisibilityPublic)
1014 return false;
1015 }
1016 }
1017 if (!VS->isLive())
1018 continue;
1019 for (auto VTP : VS->vTableFuncs()) {
1020 if (VTP.VTableOffset != P.AddressPointOffset + ByteOffset)
1021 continue;
1022
1023 TargetsForSlot.push_back(VTP.FuncVI);
1024 }
1025 }
1026
1027 // Give up if we couldn't find any targets.
1028 return !TargetsForSlot.empty();
1029}
1030
1031void DevirtModule::applySingleImplDevirt(VTableSlotInfo &SlotInfo,
1032 Constant *TheFn, bool &IsExported) {
1033 auto Apply = [&](CallSiteInfo &CSInfo) {
1034 for (auto &&VCallSite : CSInfo.CallSites) {
1035 if (RemarksEnabled)
1036 VCallSite.emitRemark("single-impl",
1037 TheFn->stripPointerCasts()->getName(), OREGetter);
1038 VCallSite.CB.setCalledOperand(ConstantExpr::getBitCast(
1039 TheFn, VCallSite.CB.getCalledOperand()->getType()));
1040 // This use is no longer unsafe.
1041 if (VCallSite.NumUnsafeUses)
1042 --*VCallSite.NumUnsafeUses;
1043 }
1044 if (CSInfo.isExported())
1045 IsExported = true;
1046 CSInfo.markDevirt();
1047 };
1048 Apply(SlotInfo.CSInfo);
1049 for (auto &P : SlotInfo.ConstCSInfo)
1050 Apply(P.second);
1051}
32
Returning without writing to 'IsExported', which participates in a condition later
1052
1053static bool AddCalls(VTableSlotInfo &SlotInfo, const ValueInfo &Callee) {
1054 // We can't add calls if we haven't seen a definition
1055 if (Callee.getSummaryList().empty())
1056 return false;
1057
1058 // Insert calls into the summary index so that the devirtualized targets
1059 // are eligible for import.
1060 // FIXME: Annotate type tests with hotness. For now, mark these as hot
1061 // to better ensure we have the opportunity to inline them.
1062 bool IsExported = false;
1063 auto &S = Callee.getSummaryList()[0];
1064 CalleeInfo CI(CalleeInfo::HotnessType::Hot, /* RelBF = */ 0);
1065 auto AddCalls = [&](CallSiteInfo &CSInfo) {
1066 for (auto *FS : CSInfo.SummaryTypeCheckedLoadUsers) {
1067 FS->addCall({Callee, CI});
1068 IsExported |= S->modulePath() != FS->modulePath();
1069 }
1070 for (auto *FS : CSInfo.SummaryTypeTestAssumeUsers) {
1071 FS->addCall({Callee, CI});
1072 IsExported |= S->modulePath() != FS->modulePath();
1073 }
1074 };
1075 AddCalls(SlotInfo.CSInfo);
1076 for (auto &P : SlotInfo.ConstCSInfo)
1077 AddCalls(P.second);
1078 return IsExported;
1079}
1080
1081bool DevirtModule::trySingleImplDevirt(
1082 ModuleSummaryIndex *ExportSummary,
1083 MutableArrayRef<VirtualCallTarget> TargetsForSlot, VTableSlotInfo &SlotInfo,
1084 WholeProgramDevirtResolution *Res) {
1085 // See if the program contains a single implementation of this virtual
1086 // function.
1087 Function *TheFn = TargetsForSlot[0].Fn;
1088 for (auto &&Target : TargetsForSlot)
28
Assuming '__begin1' is equal to '__end1'
1089 if (TheFn != Target.Fn)
1090 return false;
1091
1092 // If so, update each call site to call that implementation directly.
1093 if (RemarksEnabled)
29
Assuming field 'RemarksEnabled' is false
30
Taking false branch
1094 TargetsForSlot[0].WasDevirt = true;
1095
1096 bool IsExported = false;
1097 applySingleImplDevirt(SlotInfo, TheFn, IsExported);
31
Calling 'DevirtModule::applySingleImplDevirt'
33
Returning from 'DevirtModule::applySingleImplDevirt'
1098 if (!IsExported
33.1
'IsExported' is false
33.1
'IsExported' is false
)
34
Taking true branch
1099 return false;
35
Returning zero, which participates in a condition later
1100
1101 // If the only implementation has local linkage, we must promote to external
1102 // to make it visible to thin LTO objects. We can only get here during the
1103 // ThinLTO export phase.
1104 if (TheFn->hasLocalLinkage()) {
1105 std::string NewName = (TheFn->getName() + "$merged").str();
1106
1107 // Since we are renaming the function, any comdats with the same name must
1108 // also be renamed. This is required when targeting COFF, as the comdat name
1109 // must match one of the names of the symbols in the comdat.
1110 if (Comdat *C = TheFn->getComdat()) {
1111 if (C->getName() == TheFn->getName()) {
1112 Comdat *NewC = M.getOrInsertComdat(NewName);
1113 NewC->setSelectionKind(C->getSelectionKind());
1114 for (GlobalObject &GO : M.global_objects())
1115 if (GO.getComdat() == C)
1116 GO.setComdat(NewC);
1117 }
1118 }
1119
1120 TheFn->setLinkage(GlobalValue::ExternalLinkage);
1121 TheFn->setVisibility(GlobalValue::HiddenVisibility);
1122 TheFn->setName(NewName);
1123 }
1124 if (ValueInfo TheFnVI = ExportSummary->getValueInfo(TheFn->getGUID()))
1125 // Any needed promotion of 'TheFn' has already been done during
1126 // LTO unit split, so we can ignore return value of AddCalls.
1127 AddCalls(SlotInfo, TheFnVI);
1128
1129 Res->TheKind = WholeProgramDevirtResolution::SingleImpl;
1130 Res->SingleImplName = std::string(TheFn->getName());
1131
1132 return true;
1133}
1134
1135bool DevirtIndex::trySingleImplDevirt(MutableArrayRef<ValueInfo> TargetsForSlot,
1136 VTableSlotSummary &SlotSummary,
1137 VTableSlotInfo &SlotInfo,
1138 WholeProgramDevirtResolution *Res,
1139 std::set<ValueInfo> &DevirtTargets) {
1140 // See if the program contains a single implementation of this virtual
1141 // function.
1142 auto TheFn = TargetsForSlot[0];
1143 for (auto &&Target : TargetsForSlot)
1144 if (TheFn != Target)
1145 return false;
1146
1147 // Don't devirtualize if we don't have target definition.
1148 auto Size = TheFn.getSummaryList().size();
1149 if (!Size)
1150 return false;
1151
1152 // Don't devirtualize function if we're told to skip it
1153 // in -wholeprogramdevirt-skip.
1154 if (FunctionsToSkip.match(TheFn.name()))
1155 return false;
1156
1157 // If the summary list contains multiple summaries where at least one is
1158 // a local, give up, as we won't know which (possibly promoted) name to use.
1159 for (auto &S : TheFn.getSummaryList())
1160 if (GlobalValue::isLocalLinkage(S->linkage()) && Size > 1)
1161 return false;
1162
1163 // Collect functions devirtualized at least for one call site for stats.
1164 if (PrintSummaryDevirt)
1165 DevirtTargets.insert(TheFn);
1166
1167 auto &S = TheFn.getSummaryList()[0];
1168 bool IsExported = AddCalls(SlotInfo, TheFn);
1169 if (IsExported)
1170 ExportedGUIDs.insert(TheFn.getGUID());
1171
1172 // Record in summary for use in devirtualization during the ThinLTO import
1173 // step.
1174 Res->TheKind = WholeProgramDevirtResolution::SingleImpl;
1175 if (GlobalValue::isLocalLinkage(S->linkage())) {
1176 if (IsExported)
1177 // If target is a local function and we are exporting it by
1178 // devirtualizing a call in another module, we need to record the
1179 // promoted name.
1180 Res->SingleImplName = ModuleSummaryIndex::getGlobalNameForLocal(
1181 TheFn.name(), ExportSummary.getModuleHash(S->modulePath()));
1182 else {
1183 LocalWPDTargetsMap[TheFn].push_back(SlotSummary);
1184 Res->SingleImplName = std::string(TheFn.name());
1185 }
1186 } else
1187 Res->SingleImplName = std::string(TheFn.name());
1188
1189 // Name will be empty if this thin link driven off of serialized combined
1190 // index (e.g. llvm-lto). However, WPD is not supported/invoked for the
1191 // legacy LTO API anyway.
1192 assert(!Res->SingleImplName.empty())((!Res->SingleImplName.empty()) ? static_cast<void> (
0) : __assert_fail ("!Res->SingleImplName.empty()", "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 1192, __PRETTY_FUNCTION__))
;
1193
1194 return true;
1195}
1196
1197void DevirtModule::tryICallBranchFunnel(
1198 MutableArrayRef<VirtualCallTarget> TargetsForSlot, VTableSlotInfo &SlotInfo,
1199 WholeProgramDevirtResolution *Res, VTableSlot Slot) {
1200 Triple T(M.getTargetTriple());
1201 if (T.getArch() != Triple::x86_64)
45
Assuming the condition is false
46
Taking false branch
1202 return;
1203
1204 if (TargetsForSlot.size() > ClThreshold)
47
Assuming the condition is false
48
Taking false branch
1205 return;
1206
1207 bool HasNonDevirt = !SlotInfo.CSInfo.AllCallSitesDevirted;
49
Assuming field 'AllCallSitesDevirted' is true
1208 if (!HasNonDevirt
49.1
'HasNonDevirt' is false
49.1
'HasNonDevirt' is false
)
50
Taking true branch
1209 for (auto &P : SlotInfo.ConstCSInfo)
1210 if (!P.second.AllCallSitesDevirted) {
51
Assuming field 'AllCallSitesDevirted' is false
52
Taking true branch
1211 HasNonDevirt = true;
1212 break;
53
Execution continues on line 1215
1213 }
1214
1215 if (!HasNonDevirt
53.1
'HasNonDevirt' is true
53.1
'HasNonDevirt' is true
)
54
Taking false branch
1216 return;
1217
1218 FunctionType *FT =
1219 FunctionType::get(Type::getVoidTy(M.getContext()), {Int8PtrTy}, true);
1220 Function *JT;
1221 if (isa<MDString>(Slot.TypeID)) {
55
Assuming field 'TypeID' is not a 'MDString'
56
Taking false branch
1222 JT = Function::Create(FT, Function::ExternalLinkage,
1223 M.getDataLayout().getProgramAddressSpace(),
1224 getGlobalName(Slot, {}, "branch_funnel"), &M);
1225 JT->setVisibility(GlobalValue::HiddenVisibility);
1226 } else {
1227 JT = Function::Create(FT, Function::InternalLinkage,
1228 M.getDataLayout().getProgramAddressSpace(),
1229 "branch_funnel", &M);
1230 }
1231 JT->addAttribute(1, Attribute::Nest);
1232
1233 std::vector<Value *> JTArgs;
1234 JTArgs.push_back(JT->arg_begin());
1235 for (auto &T : TargetsForSlot) {
57
Assuming '__begin1' is equal to '__end1'
1236 JTArgs.push_back(getMemberAddr(T.TM));
1237 JTArgs.push_back(T.Fn);
1238 }
1239
1240 BasicBlock *BB = BasicBlock::Create(M.getContext(), "", JT, nullptr);
1241 Function *Intr =
1242 Intrinsic::getDeclaration(&M, llvm::Intrinsic::icall_branch_funnel, {});
1243
1244 auto *CI = CallInst::Create(Intr, JTArgs, "", BB);
1245 CI->setTailCallKind(CallInst::TCK_MustTail);
1246 ReturnInst::Create(M.getContext(), nullptr, BB);
1247
1248 bool IsExported = false;
1249 applyICallBranchFunnel(SlotInfo, JT, IsExported);
58
Calling 'DevirtModule::applyICallBranchFunnel'
69
Returning from 'DevirtModule::applyICallBranchFunnel'
1250 if (IsExported
69.1
'IsExported' is true
69.1
'IsExported' is true
)
70
Taking true branch
1251 Res->TheKind = WholeProgramDevirtResolution::BranchFunnel;
71
Access to field 'TheKind' results in a dereference of a null pointer (loaded from variable 'Res')
1252}
1253
1254void DevirtModule::applyICallBranchFunnel(VTableSlotInfo &SlotInfo,
1255 Constant *JT, bool &IsExported) {
1256 auto Apply = [&](CallSiteInfo &CSInfo) {
1257 if (CSInfo.isExported())
60
Calling 'CallSiteInfo::isExported'
63
Returning from 'CallSiteInfo::isExported'
64
Taking true branch
1258 IsExported = true;
65
The value 1 is assigned to 'IsExported', which participates in a condition later
1259 if (CSInfo.AllCallSitesDevirted)
66
Assuming field 'AllCallSitesDevirted' is true
67
Taking true branch
1260 return;
1261 for (auto &&VCallSite : CSInfo.CallSites) {
1262 CallBase &CB = VCallSite.CB;
1263
1264 // Jump tables are only profitable if the retpoline mitigation is enabled.
1265 Attribute FSAttr = CB.getCaller()->getFnAttribute("target-features");
1266 if (!FSAttr.isValid() ||
1267 !FSAttr.getValueAsString().contains("+retpoline"))
1268 continue;
1269
1270 if (RemarksEnabled)
1271 VCallSite.emitRemark("branch-funnel",
1272 JT->stripPointerCasts()->getName(), OREGetter);
1273
1274 // Pass the address of the vtable in the nest register, which is r10 on
1275 // x86_64.
1276 std::vector<Type *> NewArgs;
1277 NewArgs.push_back(Int8PtrTy);
1278 for (Type *T : CB.getFunctionType()->params())
1279 NewArgs.push_back(T);
1280 FunctionType *NewFT =
1281 FunctionType::get(CB.getFunctionType()->getReturnType(), NewArgs,
1282 CB.getFunctionType()->isVarArg());
1283 PointerType *NewFTPtr = PointerType::getUnqual(NewFT);
1284
1285 IRBuilder<> IRB(&CB);
1286 std::vector<Value *> Args;
1287 Args.push_back(IRB.CreateBitCast(VCallSite.VTable, Int8PtrTy));
1288 Args.insert(Args.end(), CB.arg_begin(), CB.arg_end());
1289
1290 CallBase *NewCS = nullptr;
1291 if (isa<CallInst>(CB))
1292 NewCS = IRB.CreateCall(NewFT, IRB.CreateBitCast(JT, NewFTPtr), Args);
1293 else
1294 NewCS = IRB.CreateInvoke(NewFT, IRB.CreateBitCast(JT, NewFTPtr),
1295 cast<InvokeInst>(CB).getNormalDest(),
1296 cast<InvokeInst>(CB).getUnwindDest(), Args);
1297 NewCS->setCallingConv(CB.getCallingConv());
1298
1299 AttributeList Attrs = CB.getAttributes();
1300 std::vector<AttributeSet> NewArgAttrs;
1301 NewArgAttrs.push_back(AttributeSet::get(
1302 M.getContext(), ArrayRef<Attribute>{Attribute::get(
1303 M.getContext(), Attribute::Nest)}));
1304 for (unsigned I = 0; I + 2 < Attrs.getNumAttrSets(); ++I)
1305 NewArgAttrs.push_back(Attrs.getParamAttributes(I));
1306 NewCS->setAttributes(
1307 AttributeList::get(M.getContext(), Attrs.getFnAttributes(),
1308 Attrs.getRetAttributes(), NewArgAttrs));
1309
1310 CB.replaceAllUsesWith(NewCS);
1311 CB.eraseFromParent();
1312
1313 // This use is no longer unsafe.
1314 if (VCallSite.NumUnsafeUses)
1315 --*VCallSite.NumUnsafeUses;
1316 }
1317 // Don't mark as devirtualized because there may be callers compiled without
1318 // retpoline mitigation, which would mean that they are lowered to
1319 // llvm.type.test and therefore require an llvm.type.test resolution for the
1320 // type identifier.
1321 };
1322 Apply(SlotInfo.CSInfo);
59
Calling 'operator()'
68
Returning from 'operator()'
1323 for (auto &P : SlotInfo.ConstCSInfo)
1324 Apply(P.second);
1325}
1326
1327bool DevirtModule::tryEvaluateFunctionsWithArgs(
1328 MutableArrayRef<VirtualCallTarget> TargetsForSlot,
1329 ArrayRef<uint64_t> Args) {
1330 // Evaluate each function and store the result in each target's RetVal
1331 // field.
1332 for (VirtualCallTarget &Target : TargetsForSlot) {
1333 if (Target.Fn->arg_size() != Args.size() + 1)
1334 return false;
1335
1336 Evaluator Eval(M.getDataLayout(), nullptr);
1337 SmallVector<Constant *, 2> EvalArgs;
1338 EvalArgs.push_back(
1339 Constant::getNullValue(Target.Fn->getFunctionType()->getParamType(0)));
1340 for (unsigned I = 0; I != Args.size(); ++I) {
1341 auto *ArgTy = dyn_cast<IntegerType>(
1342 Target.Fn->getFunctionType()->getParamType(I + 1));
1343 if (!ArgTy)
1344 return false;
1345 EvalArgs.push_back(ConstantInt::get(ArgTy, Args[I]));
1346 }
1347
1348 Constant *RetVal;
1349 if (!Eval.EvaluateFunction(Target.Fn, RetVal, EvalArgs) ||
1350 !isa<ConstantInt>(RetVal))
1351 return false;
1352 Target.RetVal = cast<ConstantInt>(RetVal)->getZExtValue();
1353 }
1354 return true;
1355}
1356
1357void DevirtModule::applyUniformRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
1358 uint64_t TheRetVal) {
1359 for (auto Call : CSInfo.CallSites)
1360 Call.replaceAndErase(
1361 "uniform-ret-val", FnName, RemarksEnabled, OREGetter,
1362 ConstantInt::get(cast<IntegerType>(Call.CB.getType()), TheRetVal));
1363 CSInfo.markDevirt();
1364}
1365
1366bool DevirtModule::tryUniformRetValOpt(
1367 MutableArrayRef<VirtualCallTarget> TargetsForSlot, CallSiteInfo &CSInfo,
1368 WholeProgramDevirtResolution::ByArg *Res) {
1369 // Uniform return value optimization. If all functions return the same
1370 // constant, replace all calls with that constant.
1371 uint64_t TheRetVal = TargetsForSlot[0].RetVal;
1372 for (const VirtualCallTarget &Target : TargetsForSlot)
1373 if (Target.RetVal != TheRetVal)
1374 return false;
1375
1376 if (CSInfo.isExported()) {
1377 Res->TheKind = WholeProgramDevirtResolution::ByArg::UniformRetVal;
1378 Res->Info = TheRetVal;
1379 }
1380
1381 applyUniformRetValOpt(CSInfo, TargetsForSlot[0].Fn->getName(), TheRetVal);
1382 if (RemarksEnabled)
1383 for (auto &&Target : TargetsForSlot)
1384 Target.WasDevirt = true;
1385 return true;
1386}
1387
1388std::string DevirtModule::getGlobalName(VTableSlot Slot,
1389 ArrayRef<uint64_t> Args,
1390 StringRef Name) {
1391 std::string FullName = "__typeid_";
1392 raw_string_ostream OS(FullName);
1393 OS << cast<MDString>(Slot.TypeID)->getString() << '_' << Slot.ByteOffset;
1394 for (uint64_t Arg : Args)
1395 OS << '_' << Arg;
1396 OS << '_' << Name;
1397 return OS.str();
1398}
1399
1400bool DevirtModule::shouldExportConstantsAsAbsoluteSymbols() {
1401 Triple T(M.getTargetTriple());
1402 return T.isX86() && T.getObjectFormat() == Triple::ELF;
1403}
1404
1405void DevirtModule::exportGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
1406 StringRef Name, Constant *C) {
1407 GlobalAlias *GA = GlobalAlias::create(Int8Ty, 0, GlobalValue::ExternalLinkage,
1408 getGlobalName(Slot, Args, Name), C, &M);
1409 GA->setVisibility(GlobalValue::HiddenVisibility);
1410}
1411
1412void DevirtModule::exportConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
1413 StringRef Name, uint32_t Const,
1414 uint32_t &Storage) {
1415 if (shouldExportConstantsAsAbsoluteSymbols()) {
1416 exportGlobal(
1417 Slot, Args, Name,
1418 ConstantExpr::getIntToPtr(ConstantInt::get(Int32Ty, Const), Int8PtrTy));
1419 return;
1420 }
1421
1422 Storage = Const;
1423}
1424
1425Constant *DevirtModule::importGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
1426 StringRef Name) {
1427 Constant *C =
1428 M.getOrInsertGlobal(getGlobalName(Slot, Args, Name), Int8Arr0Ty);
1429 auto *GV = dyn_cast<GlobalVariable>(C);
1430 if (GV)
1431 GV->setVisibility(GlobalValue::HiddenVisibility);
1432 return C;
1433}
1434
1435Constant *DevirtModule::importConstant(VTableSlot Slot, ArrayRef<uint64_t> Args,
1436 StringRef Name, IntegerType *IntTy,
1437 uint32_t Storage) {
1438 if (!shouldExportConstantsAsAbsoluteSymbols())
1439 return ConstantInt::get(IntTy, Storage);
1440
1441 Constant *C = importGlobal(Slot, Args, Name);
1442 auto *GV = cast<GlobalVariable>(C->stripPointerCasts());
1443 C = ConstantExpr::getPtrToInt(C, IntTy);
1444
1445 // We only need to set metadata if the global is newly created, in which
1446 // case it would not have hidden visibility.
1447 if (GV->hasMetadata(LLVMContext::MD_absolute_symbol))
1448 return C;
1449
1450 auto SetAbsRange = [&](uint64_t Min, uint64_t Max) {
1451 auto *MinC = ConstantAsMetadata::get(ConstantInt::get(IntPtrTy, Min));
1452 auto *MaxC = ConstantAsMetadata::get(ConstantInt::get(IntPtrTy, Max));
1453 GV->setMetadata(LLVMContext::MD_absolute_symbol,
1454 MDNode::get(M.getContext(), {MinC, MaxC}));
1455 };
1456 unsigned AbsWidth = IntTy->getBitWidth();
1457 if (AbsWidth == IntPtrTy->getBitWidth())
1458 SetAbsRange(~0ull, ~0ull); // Full set.
1459 else
1460 SetAbsRange(0, 1ull << AbsWidth);
1461 return C;
1462}
1463
1464void DevirtModule::applyUniqueRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
1465 bool IsOne,
1466 Constant *UniqueMemberAddr) {
1467 for (auto &&Call : CSInfo.CallSites) {
1468 IRBuilder<> B(&Call.CB);
1469 Value *Cmp =
1470 B.CreateICmp(IsOne ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE, Call.VTable,
1471 B.CreateBitCast(UniqueMemberAddr, Call.VTable->getType()));
1472 Cmp = B.CreateZExt(Cmp, Call.CB.getType());
1473 Call.replaceAndErase("unique-ret-val", FnName, RemarksEnabled, OREGetter,
1474 Cmp);
1475 }
1476 CSInfo.markDevirt();
1477}
1478
1479Constant *DevirtModule::getMemberAddr(const TypeMemberInfo *M) {
1480 Constant *C = ConstantExpr::getBitCast(M->Bits->GV, Int8PtrTy);
1481 return ConstantExpr::getGetElementPtr(Int8Ty, C,
1482 ConstantInt::get(Int64Ty, M->Offset));
1483}
1484
1485bool DevirtModule::tryUniqueRetValOpt(
1486 unsigned BitWidth, MutableArrayRef<VirtualCallTarget> TargetsForSlot,
1487 CallSiteInfo &CSInfo, WholeProgramDevirtResolution::ByArg *Res,
1488 VTableSlot Slot, ArrayRef<uint64_t> Args) {
1489 // IsOne controls whether we look for a 0 or a 1.
1490 auto tryUniqueRetValOptFor = [&](bool IsOne) {
1491 const TypeMemberInfo *UniqueMember = nullptr;
1492 for (const VirtualCallTarget &Target : TargetsForSlot) {
1493 if (Target.RetVal == (IsOne ? 1 : 0)) {
1494 if (UniqueMember)
1495 return false;
1496 UniqueMember = Target.TM;
1497 }
1498 }
1499
1500 // We should have found a unique member or bailed out by now. We already
1501 // checked for a uniform return value in tryUniformRetValOpt.
1502 assert(UniqueMember)((UniqueMember) ? static_cast<void> (0) : __assert_fail
("UniqueMember", "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 1502, __PRETTY_FUNCTION__))
;
1503
1504 Constant *UniqueMemberAddr = getMemberAddr(UniqueMember);
1505 if (CSInfo.isExported()) {
1506 Res->TheKind = WholeProgramDevirtResolution::ByArg::UniqueRetVal;
1507 Res->Info = IsOne;
1508
1509 exportGlobal(Slot, Args, "unique_member", UniqueMemberAddr);
1510 }
1511
1512 // Replace each call with the comparison.
1513 applyUniqueRetValOpt(CSInfo, TargetsForSlot[0].Fn->getName(), IsOne,
1514 UniqueMemberAddr);
1515
1516 // Update devirtualization statistics for targets.
1517 if (RemarksEnabled)
1518 for (auto &&Target : TargetsForSlot)
1519 Target.WasDevirt = true;
1520
1521 return true;
1522 };
1523
1524 if (BitWidth == 1) {
1525 if (tryUniqueRetValOptFor(true))
1526 return true;
1527 if (tryUniqueRetValOptFor(false))
1528 return true;
1529 }
1530 return false;
1531}
1532
1533void DevirtModule::applyVirtualConstProp(CallSiteInfo &CSInfo, StringRef FnName,
1534 Constant *Byte, Constant *Bit) {
1535 for (auto Call : CSInfo.CallSites) {
1536 auto *RetType = cast<IntegerType>(Call.CB.getType());
1537 IRBuilder<> B(&Call.CB);
1538 Value *Addr =
1539 B.CreateGEP(Int8Ty, B.CreateBitCast(Call.VTable, Int8PtrTy), Byte);
1540 if (RetType->getBitWidth() == 1) {
1541 Value *Bits = B.CreateLoad(Int8Ty, Addr);
1542 Value *BitsAndBit = B.CreateAnd(Bits, Bit);
1543 auto IsBitSet = B.CreateICmpNE(BitsAndBit, ConstantInt::get(Int8Ty, 0));
1544 Call.replaceAndErase("virtual-const-prop-1-bit", FnName, RemarksEnabled,
1545 OREGetter, IsBitSet);
1546 } else {
1547 Value *ValAddr = B.CreateBitCast(Addr, RetType->getPointerTo());
1548 Value *Val = B.CreateLoad(RetType, ValAddr);
1549 Call.replaceAndErase("virtual-const-prop", FnName, RemarksEnabled,
1550 OREGetter, Val);
1551 }
1552 }
1553 CSInfo.markDevirt();
1554}
1555
1556bool DevirtModule::tryVirtualConstProp(
1557 MutableArrayRef<VirtualCallTarget> TargetsForSlot, VTableSlotInfo &SlotInfo,
1558 WholeProgramDevirtResolution *Res, VTableSlot Slot) {
1559 // This only works if the function returns an integer.
1560 auto RetType = dyn_cast<IntegerType>(TargetsForSlot[0].Fn->getReturnType());
39
Assuming the object is not a 'IntegerType'
1561 if (!RetType
39.1
'RetType' is null
39.1
'RetType' is null
)
40
Taking true branch
1562 return false;
41
Returning without writing to 'SlotInfo.CSInfo.AllCallSitesDevirted', which participates in a condition later
1563 unsigned BitWidth = RetType->getBitWidth();
1564 if (BitWidth > 64)
1565 return false;
1566
1567 // Make sure that each function is defined, does not access memory, takes at
1568 // least one argument, does not use its first argument (which we assume is
1569 // 'this'), and has the same return type.
1570 //
1571 // Note that we test whether this copy of the function is readnone, rather
1572 // than testing function attributes, which must hold for any copy of the
1573 // function, even a less optimized version substituted at link time. This is
1574 // sound because the virtual constant propagation optimizations effectively
1575 // inline all implementations of the virtual function into each call site,
1576 // rather than using function attributes to perform local optimization.
1577 for (VirtualCallTarget &Target : TargetsForSlot) {
1578 if (Target.Fn->isDeclaration() ||
1579 computeFunctionBodyMemoryAccess(*Target.Fn, AARGetter(*Target.Fn)) !=
1580 MAK_ReadNone ||
1581 Target.Fn->arg_empty() || !Target.Fn->arg_begin()->use_empty() ||
1582 Target.Fn->getReturnType() != RetType)
1583 return false;
1584 }
1585
1586 for (auto &&CSByConstantArg : SlotInfo.ConstCSInfo) {
1587 if (!tryEvaluateFunctionsWithArgs(TargetsForSlot, CSByConstantArg.first))
1588 continue;
1589
1590 WholeProgramDevirtResolution::ByArg *ResByArg = nullptr;
1591 if (Res)
1592 ResByArg = &Res->ResByArg[CSByConstantArg.first];
1593
1594 if (tryUniformRetValOpt(TargetsForSlot, CSByConstantArg.second, ResByArg))
1595 continue;
1596
1597 if (tryUniqueRetValOpt(BitWidth, TargetsForSlot, CSByConstantArg.second,
1598 ResByArg, Slot, CSByConstantArg.first))
1599 continue;
1600
1601 // Find an allocation offset in bits in all vtables associated with the
1602 // type.
1603 uint64_t AllocBefore =
1604 findLowestOffset(TargetsForSlot, /*IsAfter=*/false, BitWidth);
1605 uint64_t AllocAfter =
1606 findLowestOffset(TargetsForSlot, /*IsAfter=*/true, BitWidth);
1607
1608 // Calculate the total amount of padding needed to store a value at both
1609 // ends of the object.
1610 uint64_t TotalPaddingBefore = 0, TotalPaddingAfter = 0;
1611 for (auto &&Target : TargetsForSlot) {
1612 TotalPaddingBefore += std::max<int64_t>(
1613 (AllocBefore + 7) / 8 - Target.allocatedBeforeBytes() - 1, 0);
1614 TotalPaddingAfter += std::max<int64_t>(
1615 (AllocAfter + 7) / 8 - Target.allocatedAfterBytes() - 1, 0);
1616 }
1617
1618 // If the amount of padding is too large, give up.
1619 // FIXME: do something smarter here.
1620 if (std::min(TotalPaddingBefore, TotalPaddingAfter) > 128)
1621 continue;
1622
1623 // Calculate the offset to the value as a (possibly negative) byte offset
1624 // and (if applicable) a bit offset, and store the values in the targets.
1625 int64_t OffsetByte;
1626 uint64_t OffsetBit;
1627 if (TotalPaddingBefore <= TotalPaddingAfter)
1628 setBeforeReturnValues(TargetsForSlot, AllocBefore, BitWidth, OffsetByte,
1629 OffsetBit);
1630 else
1631 setAfterReturnValues(TargetsForSlot, AllocAfter, BitWidth, OffsetByte,
1632 OffsetBit);
1633
1634 if (RemarksEnabled)
1635 for (auto &&Target : TargetsForSlot)
1636 Target.WasDevirt = true;
1637
1638
1639 if (CSByConstantArg.second.isExported()) {
1640 ResByArg->TheKind = WholeProgramDevirtResolution::ByArg::VirtualConstProp;
1641 exportConstant(Slot, CSByConstantArg.first, "byte", OffsetByte,
1642 ResByArg->Byte);
1643 exportConstant(Slot, CSByConstantArg.first, "bit", 1ULL << OffsetBit,
1644 ResByArg->Bit);
1645 }
1646
1647 // Rewrite each call to a load from OffsetByte/OffsetBit.
1648 Constant *ByteConst = ConstantInt::get(Int32Ty, OffsetByte);
1649 Constant *BitConst = ConstantInt::get(Int8Ty, 1ULL << OffsetBit);
1650 applyVirtualConstProp(CSByConstantArg.second,
1651 TargetsForSlot[0].Fn->getName(), ByteConst, BitConst);
1652 }
1653 return true;
1654}
1655
1656void DevirtModule::rebuildGlobal(VTableBits &B) {
1657 if (B.Before.Bytes.empty() && B.After.Bytes.empty())
1658 return;
1659
1660 // Align the before byte array to the global's minimum alignment so that we
1661 // don't break any alignment requirements on the global.
1662 Align Alignment = M.getDataLayout().getValueOrABITypeAlignment(
1663 B.GV->getAlign(), B.GV->getValueType());
1664 B.Before.Bytes.resize(alignTo(B.Before.Bytes.size(), Alignment));
1665
1666 // Before was stored in reverse order; flip it now.
1667 for (size_t I = 0, Size = B.Before.Bytes.size(); I != Size / 2; ++I)
1668 std::swap(B.Before.Bytes[I], B.Before.Bytes[Size - 1 - I]);
1669
1670 // Build an anonymous global containing the before bytes, followed by the
1671 // original initializer, followed by the after bytes.
1672 auto NewInit = ConstantStruct::getAnon(
1673 {ConstantDataArray::get(M.getContext(), B.Before.Bytes),
1674 B.GV->getInitializer(),
1675 ConstantDataArray::get(M.getContext(), B.After.Bytes)});
1676 auto NewGV =
1677 new GlobalVariable(M, NewInit->getType(), B.GV->isConstant(),
1678 GlobalVariable::PrivateLinkage, NewInit, "", B.GV);
1679 NewGV->setSection(B.GV->getSection());
1680 NewGV->setComdat(B.GV->getComdat());
1681 NewGV->setAlignment(MaybeAlign(B.GV->getAlignment()));
1682
1683 // Copy the original vtable's metadata to the anonymous global, adjusting
1684 // offsets as required.
1685 NewGV->copyMetadata(B.GV, B.Before.Bytes.size());
1686
1687 // Build an alias named after the original global, pointing at the second
1688 // element (the original initializer).
1689 auto Alias = GlobalAlias::create(
1690 B.GV->getInitializer()->getType(), 0, B.GV->getLinkage(), "",
1691 ConstantExpr::getGetElementPtr(
1692 NewInit->getType(), NewGV,
1693 ArrayRef<Constant *>{ConstantInt::get(Int32Ty, 0),
1694 ConstantInt::get(Int32Ty, 1)}),
1695 &M);
1696 Alias->setVisibility(B.GV->getVisibility());
1697 Alias->takeName(B.GV);
1698
1699 B.GV->replaceAllUsesWith(Alias);
1700 B.GV->eraseFromParent();
1701}
1702
1703bool DevirtModule::areRemarksEnabled() {
1704 const auto &FL = M.getFunctionList();
1705 for (const Function &Fn : FL) {
1706 const auto &BBL = Fn.getBasicBlockList();
1707 if (BBL.empty())
1708 continue;
1709 auto DI = OptimizationRemark(DEBUG_TYPE"wholeprogramdevirt", "", DebugLoc(), &BBL.front());
1710 return DI.isEnabled();
1711 }
1712 return false;
1713}
1714
1715void DevirtModule::scanTypeTestUsers(
1716 Function *TypeTestFunc,
1717 DenseMap<Metadata *, std::set<TypeMemberInfo>> &TypeIdMap) {
1718 // Find all virtual calls via a virtual table pointer %p under an assumption
1719 // of the form llvm.assume(llvm.type.test(%p, %md)). This indicates that %p
1720 // points to a member of the type identifier %md. Group calls by (type ID,
1721 // offset) pair (effectively the identity of the virtual function) and store
1722 // to CallSlots.
1723 for (auto I = TypeTestFunc->use_begin(), E = TypeTestFunc->use_end();
1724 I != E;) {
1725 auto CI = dyn_cast<CallInst>(I->getUser());
1726 ++I;
1727 if (!CI)
1728 continue;
1729
1730 // Search for virtual calls based on %p and add them to DevirtCalls.
1731 SmallVector<DevirtCallSite, 1> DevirtCalls;
1732 SmallVector<CallInst *, 1> Assumes;
1733 auto &DT = LookupDomTree(*CI->getFunction());
1734 findDevirtualizableCallsForTypeTest(DevirtCalls, Assumes, CI, DT);
1735
1736 Metadata *TypeId =
1737 cast<MetadataAsValue>(CI->getArgOperand(1))->getMetadata();
1738 // If we found any, add them to CallSlots.
1739 if (!Assumes.empty()) {
1740 Value *Ptr = CI->getArgOperand(0)->stripPointerCasts();
1741 for (DevirtCallSite Call : DevirtCalls)
1742 CallSlots[{TypeId, Call.Offset}].addCallSite(Ptr, Call.CB, nullptr);
1743 }
1744
1745 auto RemoveTypeTestAssumes = [&]() {
1746 // We no longer need the assumes or the type test.
1747 for (auto Assume : Assumes)
1748 Assume->eraseFromParent();
1749 // We can't use RecursivelyDeleteTriviallyDeadInstructions here because we
1750 // may use the vtable argument later.
1751 if (CI->use_empty())
1752 CI->eraseFromParent();
1753 };
1754
1755 // At this point we could remove all type test assume sequences, as they
1756 // were originally inserted for WPD. However, we can keep these in the
1757 // code stream for later analysis (e.g. to help drive more efficient ICP
1758 // sequences). They will eventually be removed by a second LowerTypeTests
1759 // invocation that cleans them up. In order to do this correctly, the first
1760 // LowerTypeTests invocation needs to know that they have "Unknown" type
1761 // test resolution, so that they aren't treated as Unsat and lowered to
1762 // False, which will break any uses on assumes. Below we remove any type
1763 // test assumes that will not be treated as Unknown by LTT.
1764
1765 // The type test assumes will be treated by LTT as Unsat if the type id is
1766 // not used on a global (in which case it has no entry in the TypeIdMap).
1767 if (!TypeIdMap.count(TypeId))
1768 RemoveTypeTestAssumes();
1769
1770 // For ThinLTO importing, we need to remove the type test assumes if this is
1771 // an MDString type id without a corresponding TypeIdSummary. Any
1772 // non-MDString type ids are ignored and treated as Unknown by LTT, so their
1773 // type test assumes can be kept. If the MDString type id is missing a
1774 // TypeIdSummary (e.g. because there was no use on a vcall, preventing the
1775 // exporting phase of WPD from analyzing it), then it would be treated as
1776 // Unsat by LTT and we need to remove its type test assumes here. If not
1777 // used on a vcall we don't need them for later optimization use in any
1778 // case.
1779 else if (ImportSummary && isa<MDString>(TypeId)) {
1780 const TypeIdSummary *TidSummary =
1781 ImportSummary->getTypeIdSummary(cast<MDString>(TypeId)->getString());
1782 if (!TidSummary)
1783 RemoveTypeTestAssumes();
1784 else
1785 // If one was created it should not be Unsat, because if we reached here
1786 // the type id was used on a global.
1787 assert(TidSummary->TTRes.TheKind != TypeTestResolution::Unsat)((TidSummary->TTRes.TheKind != TypeTestResolution::Unsat) ?
static_cast<void> (0) : __assert_fail ("TidSummary->TTRes.TheKind != TypeTestResolution::Unsat"
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 1787, __PRETTY_FUNCTION__))
;
1788 }
1789 }
1790}
1791
1792void DevirtModule::scanTypeCheckedLoadUsers(Function *TypeCheckedLoadFunc) {
1793 Function *TypeTestFunc = Intrinsic::getDeclaration(&M, Intrinsic::type_test);
1794
1795 for (auto I = TypeCheckedLoadFunc->use_begin(),
1796 E = TypeCheckedLoadFunc->use_end();
1797 I != E;) {
1798 auto CI = dyn_cast<CallInst>(I->getUser());
1799 ++I;
1800 if (!CI)
1801 continue;
1802
1803 Value *Ptr = CI->getArgOperand(0);
1804 Value *Offset = CI->getArgOperand(1);
1805 Value *TypeIdValue = CI->getArgOperand(2);
1806 Metadata *TypeId = cast<MetadataAsValue>(TypeIdValue)->getMetadata();
1807
1808 SmallVector<DevirtCallSite, 1> DevirtCalls;
1809 SmallVector<Instruction *, 1> LoadedPtrs;
1810 SmallVector<Instruction *, 1> Preds;
1811 bool HasNonCallUses = false;
1812 auto &DT = LookupDomTree(*CI->getFunction());
1813 findDevirtualizableCallsForTypeCheckedLoad(DevirtCalls, LoadedPtrs, Preds,
1814 HasNonCallUses, CI, DT);
1815
1816 // Start by generating "pessimistic" code that explicitly loads the function
1817 // pointer from the vtable and performs the type check. If possible, we will
1818 // eliminate the load and the type check later.
1819
1820 // If possible, only generate the load at the point where it is used.
1821 // This helps avoid unnecessary spills.
1822 IRBuilder<> LoadB(
1823 (LoadedPtrs.size() == 1 && !HasNonCallUses) ? LoadedPtrs[0] : CI);
1824 Value *GEP = LoadB.CreateGEP(Int8Ty, Ptr, Offset);
1825 Value *GEPPtr = LoadB.CreateBitCast(GEP, PointerType::getUnqual(Int8PtrTy));
1826 Value *LoadedValue = LoadB.CreateLoad(Int8PtrTy, GEPPtr);
1827
1828 for (Instruction *LoadedPtr : LoadedPtrs) {
1829 LoadedPtr->replaceAllUsesWith(LoadedValue);
1830 LoadedPtr->eraseFromParent();
1831 }
1832
1833 // Likewise for the type test.
1834 IRBuilder<> CallB((Preds.size() == 1 && !HasNonCallUses) ? Preds[0] : CI);
1835 CallInst *TypeTestCall = CallB.CreateCall(TypeTestFunc, {Ptr, TypeIdValue});
1836
1837 for (Instruction *Pred : Preds) {
1838 Pred->replaceAllUsesWith(TypeTestCall);
1839 Pred->eraseFromParent();
1840 }
1841
1842 // We have already erased any extractvalue instructions that refer to the
1843 // intrinsic call, but the intrinsic may have other non-extractvalue uses
1844 // (although this is unlikely). In that case, explicitly build a pair and
1845 // RAUW it.
1846 if (!CI->use_empty()) {
1847 Value *Pair = UndefValue::get(CI->getType());
1848 IRBuilder<> B(CI);
1849 Pair = B.CreateInsertValue(Pair, LoadedValue, {0});
1850 Pair = B.CreateInsertValue(Pair, TypeTestCall, {1});
1851 CI->replaceAllUsesWith(Pair);
1852 }
1853
1854 // The number of unsafe uses is initially the number of uses.
1855 auto &NumUnsafeUses = NumUnsafeUsesForTypeTest[TypeTestCall];
1856 NumUnsafeUses = DevirtCalls.size();
1857
1858 // If the function pointer has a non-call user, we cannot eliminate the type
1859 // check, as one of those users may eventually call the pointer. Increment
1860 // the unsafe use count to make sure it cannot reach zero.
1861 if (HasNonCallUses)
1862 ++NumUnsafeUses;
1863 for (DevirtCallSite Call : DevirtCalls) {
1864 CallSlots[{TypeId, Call.Offset}].addCallSite(Ptr, Call.CB,
1865 &NumUnsafeUses);
1866 }
1867
1868 CI->eraseFromParent();
1869 }
1870}
1871
1872void DevirtModule::importResolution(VTableSlot Slot, VTableSlotInfo &SlotInfo) {
1873 auto *TypeId = dyn_cast<MDString>(Slot.TypeID);
1874 if (!TypeId)
1875 return;
1876 const TypeIdSummary *TidSummary =
1877 ImportSummary->getTypeIdSummary(TypeId->getString());
1878 if (!TidSummary)
1879 return;
1880 auto ResI = TidSummary->WPDRes.find(Slot.ByteOffset);
1881 if (ResI == TidSummary->WPDRes.end())
1882 return;
1883 const WholeProgramDevirtResolution &Res = ResI->second;
1884
1885 if (Res.TheKind == WholeProgramDevirtResolution::SingleImpl) {
1886 assert(!Res.SingleImplName.empty())((!Res.SingleImplName.empty()) ? static_cast<void> (0) :
__assert_fail ("!Res.SingleImplName.empty()", "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 1886, __PRETTY_FUNCTION__))
;
1887 // The type of the function in the declaration is irrelevant because every
1888 // call site will cast it to the correct type.
1889 Constant *SingleImpl =
1890 cast<Constant>(M.getOrInsertFunction(Res.SingleImplName,
1891 Type::getVoidTy(M.getContext()))
1892 .getCallee());
1893
1894 // This is the import phase so we should not be exporting anything.
1895 bool IsExported = false;
1896 applySingleImplDevirt(SlotInfo, SingleImpl, IsExported);
1897 assert(!IsExported)((!IsExported) ? static_cast<void> (0) : __assert_fail (
"!IsExported", "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 1897, __PRETTY_FUNCTION__))
;
1898 }
1899
1900 for (auto &CSByConstantArg : SlotInfo.ConstCSInfo) {
1901 auto I = Res.ResByArg.find(CSByConstantArg.first);
1902 if (I == Res.ResByArg.end())
1903 continue;
1904 auto &ResByArg = I->second;
1905 // FIXME: We should figure out what to do about the "function name" argument
1906 // to the apply* functions, as the function names are unavailable during the
1907 // importing phase. For now we just pass the empty string. This does not
1908 // impact correctness because the function names are just used for remarks.
1909 switch (ResByArg.TheKind) {
1910 case WholeProgramDevirtResolution::ByArg::UniformRetVal:
1911 applyUniformRetValOpt(CSByConstantArg.second, "", ResByArg.Info);
1912 break;
1913 case WholeProgramDevirtResolution::ByArg::UniqueRetVal: {
1914 Constant *UniqueMemberAddr =
1915 importGlobal(Slot, CSByConstantArg.first, "unique_member");
1916 applyUniqueRetValOpt(CSByConstantArg.second, "", ResByArg.Info,
1917 UniqueMemberAddr);
1918 break;
1919 }
1920 case WholeProgramDevirtResolution::ByArg::VirtualConstProp: {
1921 Constant *Byte = importConstant(Slot, CSByConstantArg.first, "byte",
1922 Int32Ty, ResByArg.Byte);
1923 Constant *Bit = importConstant(Slot, CSByConstantArg.first, "bit", Int8Ty,
1924 ResByArg.Bit);
1925 applyVirtualConstProp(CSByConstantArg.second, "", Byte, Bit);
1926 break;
1927 }
1928 default:
1929 break;
1930 }
1931 }
1932
1933 if (Res.TheKind == WholeProgramDevirtResolution::BranchFunnel) {
1934 // The type of the function is irrelevant, because it's bitcast at calls
1935 // anyhow.
1936 Constant *JT = cast<Constant>(
1937 M.getOrInsertFunction(getGlobalName(Slot, {}, "branch_funnel"),
1938 Type::getVoidTy(M.getContext()))
1939 .getCallee());
1940 bool IsExported = false;
1941 applyICallBranchFunnel(SlotInfo, JT, IsExported);
1942 assert(!IsExported)((!IsExported) ? static_cast<void> (0) : __assert_fail (
"!IsExported", "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 1942, __PRETTY_FUNCTION__))
;
1943 }
1944}
1945
1946void DevirtModule::removeRedundantTypeTests() {
1947 auto True = ConstantInt::getTrue(M.getContext());
1948 for (auto &&U : NumUnsafeUsesForTypeTest) {
1949 if (U.second == 0) {
1950 U.first->replaceAllUsesWith(True);
1951 U.first->eraseFromParent();
1952 }
1953 }
1954}
1955
1956bool DevirtModule::run() {
1957 // If only some of the modules were split, we cannot correctly perform
1958 // this transformation. We already checked for the presense of type tests
1959 // with partially split modules during the thin link, and would have emitted
1960 // an error if any were found, so here we can simply return.
1961 if ((ExportSummary && ExportSummary->partiallySplitLTOUnits()) ||
1
Assuming field 'ExportSummary' is null
1962 (ImportSummary && ImportSummary->partiallySplitLTOUnits()))
2
Assuming field 'ImportSummary' is null
1963 return false;
1964
1965 Function *TypeTestFunc =
1966 M.getFunction(Intrinsic::getName(Intrinsic::type_test));
1967 Function *TypeCheckedLoadFunc =
1968 M.getFunction(Intrinsic::getName(Intrinsic::type_checked_load));
1969 Function *AssumeFunc = M.getFunction(Intrinsic::getName(Intrinsic::assume));
1970
1971 // Normally if there are no users of the devirtualization intrinsics in the
1972 // module, this pass has nothing to do. But if we are exporting, we also need
1973 // to handle any users that appear only in the function summaries.
1974 if (!ExportSummary
2.1
Field 'ExportSummary' is null
2.1
Field 'ExportSummary' is null
&&
1975 (!TypeTestFunc || TypeTestFunc->use_empty() || !AssumeFunc ||
3
Assuming 'TypeTestFunc' is non-null
4
Calling 'Value::use_empty'
7
Returning from 'Value::use_empty'
8
Assuming 'AssumeFunc' is non-null
1976 AssumeFunc->use_empty()) &&
9
Calling 'Value::use_empty'
12
Returning from 'Value::use_empty'
1977 (!TypeCheckedLoadFunc || TypeCheckedLoadFunc->use_empty()))
1978 return false;
1979
1980 // Rebuild type metadata into a map for easy lookup.
1981 std::vector<VTableBits> Bits;
1982 DenseMap<Metadata *, std::set<TypeMemberInfo>> TypeIdMap;
1983 buildTypeIdentifierMap(Bits, TypeIdMap);
1984
1985 if (TypeTestFunc
12.1
'TypeTestFunc' is non-null
12.1
'TypeTestFunc' is non-null
&& AssumeFunc
12.2
'AssumeFunc' is non-null
12.2
'AssumeFunc' is non-null
)
13
Taking true branch
1986 scanTypeTestUsers(TypeTestFunc, TypeIdMap);
1987
1988 if (TypeCheckedLoadFunc)
14
Assuming 'TypeCheckedLoadFunc' is null
15
Taking false branch
1989 scanTypeCheckedLoadUsers(TypeCheckedLoadFunc);
1990
1991 if (ImportSummary
15.1
Field 'ImportSummary' is null
15.1
Field 'ImportSummary' is null
) {
16
Taking false branch
1992 for (auto &S : CallSlots)
1993 importResolution(S.first, S.second);
1994
1995 removeRedundantTypeTests();
1996
1997 // We have lowered or deleted the type instrinsics, so we will no
1998 // longer have enough information to reason about the liveness of virtual
1999 // function pointers in GlobalDCE.
2000 for (GlobalVariable &GV : M.globals())
2001 GV.eraseMetadata(LLVMContext::MD_vcall_visibility);
2002
2003 // The rest of the code is only necessary when exporting or during regular
2004 // LTO, so we are done.
2005 return true;
2006 }
2007
2008 if (TypeIdMap.empty())
17
Assuming the condition is false
18
Taking false branch
2009 return true;
2010
2011 // Collect information from summary about which calls to try to devirtualize.
2012 if (ExportSummary
18.1
Field 'ExportSummary' is null
18.1
Field 'ExportSummary' is null
) {
19
Taking false branch
2013 DenseMap<GlobalValue::GUID, TinyPtrVector<Metadata *>> MetadataByGUID;
2014 for (auto &P : TypeIdMap) {
2015 if (auto *TypeId = dyn_cast<MDString>(P.first))
2016 MetadataByGUID[GlobalValue::getGUID(TypeId->getString())].push_back(
2017 TypeId);
2018 }
2019
2020 for (auto &P : *ExportSummary) {
2021 for (auto &S : P.second.SummaryList) {
2022 auto *FS = dyn_cast<FunctionSummary>(S.get());
2023 if (!FS)
2024 continue;
2025 // FIXME: Only add live functions.
2026 for (FunctionSummary::VFuncId VF : FS->type_test_assume_vcalls()) {
2027 for (Metadata *MD : MetadataByGUID[VF.GUID]) {
2028 CallSlots[{MD, VF.Offset}].CSInfo.addSummaryTypeTestAssumeUser(FS);
2029 }
2030 }
2031 for (FunctionSummary::VFuncId VF : FS->type_checked_load_vcalls()) {
2032 for (Metadata *MD : MetadataByGUID[VF.GUID]) {
2033 CallSlots[{MD, VF.Offset}].CSInfo.addSummaryTypeCheckedLoadUser(FS);
2034 }
2035 }
2036 for (const FunctionSummary::ConstVCall &VC :
2037 FS->type_test_assume_const_vcalls()) {
2038 for (Metadata *MD : MetadataByGUID[VC.VFunc.GUID]) {
2039 CallSlots[{MD, VC.VFunc.Offset}]
2040 .ConstCSInfo[VC.Args]
2041 .addSummaryTypeTestAssumeUser(FS);
2042 }
2043 }
2044 for (const FunctionSummary::ConstVCall &VC :
2045 FS->type_checked_load_const_vcalls()) {
2046 for (Metadata *MD : MetadataByGUID[VC.VFunc.GUID]) {
2047 CallSlots[{MD, VC.VFunc.Offset}]
2048 .ConstCSInfo[VC.Args]
2049 .addSummaryTypeCheckedLoadUser(FS);
2050 }
2051 }
2052 }
2053 }
2054 }
2055
2056 // For each (type, offset) pair:
2057 bool DidVirtualConstProp = false;
2058 std::map<std::string, Function*> DevirtTargets;
2059 for (auto &S : CallSlots) {
2060 // Search each of the members of the type identifier for the virtual
2061 // function implementation at offset S.first.ByteOffset, and add to
2062 // TargetsForSlot.
2063 std::vector<VirtualCallTarget> TargetsForSlot;
2064 WholeProgramDevirtResolution *Res = nullptr;
20
'Res' initialized to a null pointer value
2065 const std::set<TypeMemberInfo> &TypeMemberInfos = TypeIdMap[S.first.TypeID];
2066 if (ExportSummary && isa<MDString>(S.first.TypeID) &&
21
Assuming field 'ExportSummary' is null
2067 TypeMemberInfos.size())
2068 // For any type id used on a global's type metadata, create the type id
2069 // summary resolution regardless of whether we can devirtualize, so that
2070 // lower type tests knows the type id is not Unsat. If it was not used on
2071 // a global's type metadata, the TypeIdMap entry set will be empty, and
2072 // we don't want to create an entry (with the default Unknown type
2073 // resolution), which can prevent detection of the Unsat.
2074 Res = &ExportSummary
2075 ->getOrInsertTypeIdSummary(
2076 cast<MDString>(S.first.TypeID)->getString())
2077 .WPDRes[S.first.ByteOffset];
2078 if (tryFindVirtualCallTargets(TargetsForSlot, TypeMemberInfos,
22
Calling 'DevirtModule::tryFindVirtualCallTargets'
25
Returning from 'DevirtModule::tryFindVirtualCallTargets'
26
Taking true branch
2079 S.first.ByteOffset)) {
2080
2081 if (!trySingleImplDevirt(ExportSummary, TargetsForSlot, S.second, Res)) {
27
Calling 'DevirtModule::trySingleImplDevirt'
36
Returning from 'DevirtModule::trySingleImplDevirt'
37
Taking true branch
2082 DidVirtualConstProp |=
2083 tryVirtualConstProp(TargetsForSlot, S.second, Res, S.first);
38
Calling 'DevirtModule::tryVirtualConstProp'
42
Returning from 'DevirtModule::tryVirtualConstProp'
2084
2085 tryICallBranchFunnel(TargetsForSlot, S.second, Res, S.first);
43
Passing null pointer value via 3rd parameter 'Res'
44
Calling 'DevirtModule::tryICallBranchFunnel'
2086 }
2087
2088 // Collect functions devirtualized at least for one call site for stats.
2089 if (RemarksEnabled)
2090 for (const auto &T : TargetsForSlot)
2091 if (T.WasDevirt)
2092 DevirtTargets[std::string(T.Fn->getName())] = T.Fn;
2093 }
2094
2095 // CFI-specific: if we are exporting and any llvm.type.checked.load
2096 // intrinsics were *not* devirtualized, we need to add the resulting
2097 // llvm.type.test intrinsics to the function summaries so that the
2098 // LowerTypeTests pass will export them.
2099 if (ExportSummary && isa<MDString>(S.first.TypeID)) {
2100 auto GUID =
2101 GlobalValue::getGUID(cast<MDString>(S.first.TypeID)->getString());
2102 for (auto FS : S.second.CSInfo.SummaryTypeCheckedLoadUsers)
2103 FS->addTypeTest(GUID);
2104 for (auto &CCS : S.second.ConstCSInfo)
2105 for (auto FS : CCS.second.SummaryTypeCheckedLoadUsers)
2106 FS->addTypeTest(GUID);
2107 }
2108 }
2109
2110 if (RemarksEnabled) {
2111 // Generate remarks for each devirtualized function.
2112 for (const auto &DT : DevirtTargets) {
2113 Function *F = DT.second;
2114
2115 using namespace ore;
2116 OREGetter(F).emit(OptimizationRemark(DEBUG_TYPE"wholeprogramdevirt", "Devirtualized", F)
2117 << "devirtualized "
2118 << NV("FunctionName", DT.first));
2119 }
2120 }
2121
2122 removeRedundantTypeTests();
2123
2124 // Rebuild each global we touched as part of virtual constant propagation to
2125 // include the before and after bytes.
2126 if (DidVirtualConstProp)
2127 for (VTableBits &B : Bits)
2128 rebuildGlobal(B);
2129
2130 // We have lowered or deleted the type instrinsics, so we will no
2131 // longer have enough information to reason about the liveness of virtual
2132 // function pointers in GlobalDCE.
2133 for (GlobalVariable &GV : M.globals())
2134 GV.eraseMetadata(LLVMContext::MD_vcall_visibility);
2135
2136 return true;
2137}
2138
2139void DevirtIndex::run() {
2140 if (ExportSummary.typeIdCompatibleVtableMap().empty())
2141 return;
2142
2143 DenseMap<GlobalValue::GUID, std::vector<StringRef>> NameByGUID;
2144 for (auto &P : ExportSummary.typeIdCompatibleVtableMap()) {
2145 NameByGUID[GlobalValue::getGUID(P.first)].push_back(P.first);
2146 }
2147
2148 // Collect information from summary about which calls to try to devirtualize.
2149 for (auto &P : ExportSummary) {
2150 for (auto &S : P.second.SummaryList) {
2151 auto *FS = dyn_cast<FunctionSummary>(S.get());
2152 if (!FS)
2153 continue;
2154 // FIXME: Only add live functions.
2155 for (FunctionSummary::VFuncId VF : FS->type_test_assume_vcalls()) {
2156 for (StringRef Name : NameByGUID[VF.GUID]) {
2157 CallSlots[{Name, VF.Offset}].CSInfo.addSummaryTypeTestAssumeUser(FS);
2158 }
2159 }
2160 for (FunctionSummary::VFuncId VF : FS->type_checked_load_vcalls()) {
2161 for (StringRef Name : NameByGUID[VF.GUID]) {
2162 CallSlots[{Name, VF.Offset}].CSInfo.addSummaryTypeCheckedLoadUser(FS);
2163 }
2164 }
2165 for (const FunctionSummary::ConstVCall &VC :
2166 FS->type_test_assume_const_vcalls()) {
2167 for (StringRef Name : NameByGUID[VC.VFunc.GUID]) {
2168 CallSlots[{Name, VC.VFunc.Offset}]
2169 .ConstCSInfo[VC.Args]
2170 .addSummaryTypeTestAssumeUser(FS);
2171 }
2172 }
2173 for (const FunctionSummary::ConstVCall &VC :
2174 FS->type_checked_load_const_vcalls()) {
2175 for (StringRef Name : NameByGUID[VC.VFunc.GUID]) {
2176 CallSlots[{Name, VC.VFunc.Offset}]
2177 .ConstCSInfo[VC.Args]
2178 .addSummaryTypeCheckedLoadUser(FS);
2179 }
2180 }
2181 }
2182 }
2183
2184 std::set<ValueInfo> DevirtTargets;
2185 // For each (type, offset) pair:
2186 for (auto &S : CallSlots) {
2187 // Search each of the members of the type identifier for the virtual
2188 // function implementation at offset S.first.ByteOffset, and add to
2189 // TargetsForSlot.
2190 std::vector<ValueInfo> TargetsForSlot;
2191 auto TidSummary = ExportSummary.getTypeIdCompatibleVtableSummary(S.first.TypeID);
2192 assert(TidSummary)((TidSummary) ? static_cast<void> (0) : __assert_fail (
"TidSummary", "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp"
, 2192, __PRETTY_FUNCTION__))
;
2193 // Create the type id summary resolution regardlness of whether we can
2194 // devirtualize, so that lower type tests knows the type id is used on
2195 // a global and not Unsat.
2196 WholeProgramDevirtResolution *Res =
2197 &ExportSummary.getOrInsertTypeIdSummary(S.first.TypeID)
2198 .WPDRes[S.first.ByteOffset];
2199 if (tryFindVirtualCallTargets(TargetsForSlot, *TidSummary,
2200 S.first.ByteOffset)) {
2201
2202 if (!trySingleImplDevirt(TargetsForSlot, S.first, S.second, Res,
2203 DevirtTargets))
2204 continue;
2205 }
2206 }
2207
2208 // Optionally have the thin link print message for each devirtualized
2209 // function.
2210 if (PrintSummaryDevirt)
2211 for (const auto &DT : DevirtTargets)
2212 errs() << "Devirtualized call to " << DT << "\n";
2213
2214 return;
2215}

/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/include/llvm/IR/Value.h

1//===- llvm/Value.h - Definition of the Value class -------------*- C++ -*-===//
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 file declares the Value class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_IR_VALUE_H
14#define LLVM_IR_VALUE_H
15
16#include "llvm-c/Types.h"
17#include "llvm/ADT/STLExtras.h"
18#include "llvm/ADT/StringRef.h"
19#include "llvm/ADT/iterator_range.h"
20#include "llvm/IR/Use.h"
21#include "llvm/Support/Alignment.h"
22#include "llvm/Support/CBindingWrapping.h"
23#include "llvm/Support/Casting.h"
24#include <cassert>
25#include <iterator>
26#include <memory>
27
28namespace llvm {
29
30class APInt;
31class Argument;
32class BasicBlock;
33class Constant;
34class ConstantData;
35class ConstantAggregate;
36class DataLayout;
37class Function;
38class GlobalAlias;
39class GlobalIFunc;
40class GlobalIndirectSymbol;
41class GlobalObject;
42class GlobalValue;
43class GlobalVariable;
44class InlineAsm;
45class Instruction;
46class LLVMContext;
47class MDNode;
48class Module;
49class ModuleSlotTracker;
50class raw_ostream;
51template<typename ValueTy> class StringMapEntry;
52class Twine;
53class Type;
54class User;
55
56using ValueName = StringMapEntry<Value *>;
57
58//===----------------------------------------------------------------------===//
59// Value Class
60//===----------------------------------------------------------------------===//
61
62/// LLVM Value Representation
63///
64/// This is a very important LLVM class. It is the base class of all values
65/// computed by a program that may be used as operands to other values. Value is
66/// the super class of other important classes such as Instruction and Function.
67/// All Values have a Type. Type is not a subclass of Value. Some values can
68/// have a name and they belong to some Module. Setting the name on the Value
69/// automatically updates the module's symbol table.
70///
71/// Every value has a "use list" that keeps track of which other Values are
72/// using this Value. A Value can also have an arbitrary number of ValueHandle
73/// objects that watch it and listen to RAUW and Destroy events. See
74/// llvm/IR/ValueHandle.h for details.
75class Value {
76 Type *VTy;
77 Use *UseList;
78
79 friend class ValueAsMetadata; // Allow access to IsUsedByMD.
80 friend class ValueHandleBase;
81
82 const unsigned char SubclassID; // Subclass identifier (for isa/dyn_cast)
83 unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this?
84
85protected:
86 /// Hold subclass data that can be dropped.
87 ///
88 /// This member is similar to SubclassData, however it is for holding
89 /// information which may be used to aid optimization, but which may be
90 /// cleared to zero without affecting conservative interpretation.
91 unsigned char SubclassOptionalData : 7;
92
93private:
94 /// Hold arbitrary subclass data.
95 ///
96 /// This member is defined by this class, but is not used for anything.
97 /// Subclasses can use it to hold whatever state they find useful. This
98 /// field is initialized to zero by the ctor.
99 unsigned short SubclassData;
100
101protected:
102 /// The number of operands in the subclass.
103 ///
104 /// This member is defined by this class, but not used for anything.
105 /// Subclasses can use it to store their number of operands, if they have
106 /// any.
107 ///
108 /// This is stored here to save space in User on 64-bit hosts. Since most
109 /// instances of Value have operands, 32-bit hosts aren't significantly
110 /// affected.
111 ///
112 /// Note, this should *NOT* be used directly by any class other than User.
113 /// User uses this value to find the Use list.
114 enum : unsigned { NumUserOperandsBits = 27 };
115 unsigned NumUserOperands : NumUserOperandsBits;
116
117 // Use the same type as the bitfield above so that MSVC will pack them.
118 unsigned IsUsedByMD : 1;
119 unsigned HasName : 1;
120 unsigned HasMetadata : 1; // Has metadata attached to this?
121 unsigned HasHungOffUses : 1;
122 unsigned HasDescriptor : 1;
123
124private:
125 template <typename UseT> // UseT == 'Use' or 'const Use'
126 class use_iterator_impl
127 : public std::iterator<std::forward_iterator_tag, UseT *> {
128 friend class Value;
129
130 UseT *U;
131
132 explicit use_iterator_impl(UseT *u) : U(u) {}
133
134 public:
135 use_iterator_impl() : U() {}
136
137 bool operator==(const use_iterator_impl &x) const { return U == x.U; }
138 bool operator!=(const use_iterator_impl &x) const { return !operator==(x); }
139
140 use_iterator_impl &operator++() { // Preincrement
141 assert(U && "Cannot increment end iterator!")((U && "Cannot increment end iterator!") ? static_cast
<void> (0) : __assert_fail ("U && \"Cannot increment end iterator!\""
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/include/llvm/IR/Value.h"
, 141, __PRETTY_FUNCTION__))
;
142 U = U->getNext();
143 return *this;
144 }
145
146 use_iterator_impl operator++(int) { // Postincrement
147 auto tmp = *this;
148 ++*this;
149 return tmp;
150 }
151
152 UseT &operator*() const {
153 assert(U && "Cannot dereference end iterator!")((U && "Cannot dereference end iterator!") ? static_cast
<void> (0) : __assert_fail ("U && \"Cannot dereference end iterator!\""
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/include/llvm/IR/Value.h"
, 153, __PRETTY_FUNCTION__))
;
154 return *U;
155 }
156
157 UseT *operator->() const { return &operator*(); }
158
159 operator use_iterator_impl<const UseT>() const {
160 return use_iterator_impl<const UseT>(U);
161 }
162 };
163
164 template <typename UserTy> // UserTy == 'User' or 'const User'
165 class user_iterator_impl
166 : public std::iterator<std::forward_iterator_tag, UserTy *> {
167 use_iterator_impl<Use> UI;
168 explicit user_iterator_impl(Use *U) : UI(U) {}
169 friend class Value;
170
171 public:
172 user_iterator_impl() = default;
173
174 bool operator==(const user_iterator_impl &x) const { return UI == x.UI; }
175 bool operator!=(const user_iterator_impl &x) const { return !operator==(x); }
176
177 /// Returns true if this iterator is equal to user_end() on the value.
178 bool atEnd() const { return *this == user_iterator_impl(); }
179
180 user_iterator_impl &operator++() { // Preincrement
181 ++UI;
182 return *this;
183 }
184
185 user_iterator_impl operator++(int) { // Postincrement
186 auto tmp = *this;
187 ++*this;
188 return tmp;
189 }
190
191 // Retrieve a pointer to the current User.
192 UserTy *operator*() const {
193 return UI->getUser();
194 }
195
196 UserTy *operator->() const { return operator*(); }
197
198 operator user_iterator_impl<const UserTy>() const {
199 return user_iterator_impl<const UserTy>(*UI);
200 }
201
202 Use &getUse() const { return *UI; }
203 };
204
205protected:
206 Value(Type *Ty, unsigned scid);
207
208 /// Value's destructor should be virtual by design, but that would require
209 /// that Value and all of its subclasses have a vtable that effectively
210 /// duplicates the information in the value ID. As a size optimization, the
211 /// destructor has been protected, and the caller should manually call
212 /// deleteValue.
213 ~Value(); // Use deleteValue() to delete a generic Value.
214
215public:
216 Value(const Value &) = delete;
217 Value &operator=(const Value &) = delete;
218
219 /// Delete a pointer to a generic Value.
220 void deleteValue();
221
222 /// Support for debugging, callable in GDB: V->dump()
223 void dump() const;
224
225 /// Implement operator<< on Value.
226 /// @{
227 void print(raw_ostream &O, bool IsForDebug = false) const;
228 void print(raw_ostream &O, ModuleSlotTracker &MST,
229 bool IsForDebug = false) const;
230 /// @}
231
232 /// Print the name of this Value out to the specified raw_ostream.
233 ///
234 /// This is useful when you just want to print 'int %reg126', not the
235 /// instruction that generated it. If you specify a Module for context, then
236 /// even constanst get pretty-printed; for example, the type of a null
237 /// pointer is printed symbolically.
238 /// @{
239 void printAsOperand(raw_ostream &O, bool PrintType = true,
240 const Module *M = nullptr) const;
241 void printAsOperand(raw_ostream &O, bool PrintType,
242 ModuleSlotTracker &MST) const;
243 /// @}
244
245 /// All values are typed, get the type of this value.
246 Type *getType() const { return VTy; }
247
248 /// All values hold a context through their type.
249 LLVMContext &getContext() const;
250
251 // All values can potentially be named.
252 bool hasName() const { return HasName; }
253 ValueName *getValueName() const;
254 void setValueName(ValueName *VN);
255
256private:
257 void destroyValueName();
258 enum class ReplaceMetadataUses { No, Yes };
259 void doRAUW(Value *New, ReplaceMetadataUses);
260 void setNameImpl(const Twine &Name);
261
262public:
263 /// Return a constant reference to the value's name.
264 ///
265 /// This guaranteed to return the same reference as long as the value is not
266 /// modified. If the value has a name, this does a hashtable lookup, so it's
267 /// not free.
268 StringRef getName() const;
269
270 /// Change the name of the value.
271 ///
272 /// Choose a new unique name if the provided name is taken.
273 ///
274 /// \param Name The new name; or "" if the value's name should be removed.
275 void setName(const Twine &Name);
276
277 /// Transfer the name from V to this value.
278 ///
279 /// After taking V's name, sets V's name to empty.
280 ///
281 /// \note It is an error to call V->takeName(V).
282 void takeName(Value *V);
283
284 /// Change all uses of this to point to a new Value.
285 ///
286 /// Go through the uses list for this definition and make each use point to
287 /// "V" instead of "this". After this completes, 'this's use list is
288 /// guaranteed to be empty.
289 void replaceAllUsesWith(Value *V);
290
291 /// Change non-metadata uses of this to point to a new Value.
292 ///
293 /// Go through the uses list for this definition and make each use point to
294 /// "V" instead of "this". This function skips metadata entries in the list.
295 void replaceNonMetadataUsesWith(Value *V);
296
297 /// Go through the uses list for this definition and make each use point
298 /// to "V" if the callback ShouldReplace returns true for the given Use.
299 /// Unlike replaceAllUsesWith() this function does not support basic block
300 /// values or constant users.
301 void replaceUsesWithIf(Value *New,
302 llvm::function_ref<bool(Use &U)> ShouldReplace) {
303 assert(New && "Value::replaceUsesWithIf(<null>) is invalid!")((New && "Value::replaceUsesWithIf(<null>) is invalid!"
) ? static_cast<void> (0) : __assert_fail ("New && \"Value::replaceUsesWithIf(<null>) is invalid!\""
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/include/llvm/IR/Value.h"
, 303, __PRETTY_FUNCTION__))
;
304 assert(New->getType() == getType() &&((New->getType() == getType() && "replaceUses of value with new value of different type!"
) ? static_cast<void> (0) : __assert_fail ("New->getType() == getType() && \"replaceUses of value with new value of different type!\""
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/include/llvm/IR/Value.h"
, 305, __PRETTY_FUNCTION__))
305 "replaceUses of value with new value of different type!")((New->getType() == getType() && "replaceUses of value with new value of different type!"
) ? static_cast<void> (0) : __assert_fail ("New->getType() == getType() && \"replaceUses of value with new value of different type!\""
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/include/llvm/IR/Value.h"
, 305, __PRETTY_FUNCTION__))
;
306
307 for (use_iterator UI = use_begin(), E = use_end(); UI != E;) {
308 Use &U = *UI;
309 ++UI;
310 if (!ShouldReplace(U))
311 continue;
312 U.set(New);
313 }
314 }
315
316 /// replaceUsesOutsideBlock - Go through the uses list for this definition and
317 /// make each use point to "V" instead of "this" when the use is outside the
318 /// block. 'This's use list is expected to have at least one element.
319 /// Unlike replaceAllUsesWith() this function does not support basic block
320 /// values or constant users.
321 void replaceUsesOutsideBlock(Value *V, BasicBlock *BB);
322
323 //----------------------------------------------------------------------
324 // Methods for handling the chain of uses of this Value.
325 //
326 // Materializing a function can introduce new uses, so these methods come in
327 // two variants:
328 // The methods that start with materialized_ check the uses that are
329 // currently known given which functions are materialized. Be very careful
330 // when using them since you might not get all uses.
331 // The methods that don't start with materialized_ assert that modules is
332 // fully materialized.
333 void assertModuleIsMaterializedImpl() const;
334 // This indirection exists so we can keep assertModuleIsMaterializedImpl()
335 // around in release builds of Value.cpp to be linked with other code built
336 // in debug mode. But this avoids calling it in any of the release built code.
337 void assertModuleIsMaterialized() const {
338#ifndef NDEBUG
339 assertModuleIsMaterializedImpl();
340#endif
341 }
342
343 bool use_empty() const {
344 assertModuleIsMaterialized();
345 return UseList == nullptr;
5
Assuming the condition is false
6
Returning zero, which participates in a condition later
10
Assuming the condition is false
11
Returning zero, which participates in a condition later
346 }
347
348 bool materialized_use_empty() const {
349 return UseList == nullptr;
350 }
351
352 using use_iterator = use_iterator_impl<Use>;
353 using const_use_iterator = use_iterator_impl<const Use>;
354
355 use_iterator materialized_use_begin() { return use_iterator(UseList); }
356 const_use_iterator materialized_use_begin() const {
357 return const_use_iterator(UseList);
358 }
359 use_iterator use_begin() {
360 assertModuleIsMaterialized();
361 return materialized_use_begin();
362 }
363 const_use_iterator use_begin() const {
364 assertModuleIsMaterialized();
365 return materialized_use_begin();
366 }
367 use_iterator use_end() { return use_iterator(); }
368 const_use_iterator use_end() const { return const_use_iterator(); }
369 iterator_range<use_iterator> materialized_uses() {
370 return make_range(materialized_use_begin(), use_end());
371 }
372 iterator_range<const_use_iterator> materialized_uses() const {
373 return make_range(materialized_use_begin(), use_end());
374 }
375 iterator_range<use_iterator> uses() {
376 assertModuleIsMaterialized();
377 return materialized_uses();
378 }
379 iterator_range<const_use_iterator> uses() const {
380 assertModuleIsMaterialized();
381 return materialized_uses();
382 }
383
384 bool user_empty() const {
385 assertModuleIsMaterialized();
386 return UseList == nullptr;
387 }
388
389 using user_iterator = user_iterator_impl<User>;
390 using const_user_iterator = user_iterator_impl<const User>;
391
392 user_iterator materialized_user_begin() { return user_iterator(UseList); }
393 const_user_iterator materialized_user_begin() const {
394 return const_user_iterator(UseList);
395 }
396 user_iterator user_begin() {
397 assertModuleIsMaterialized();
398 return materialized_user_begin();
399 }
400 const_user_iterator user_begin() const {
401 assertModuleIsMaterialized();
402 return materialized_user_begin();
403 }
404 user_iterator user_end() { return user_iterator(); }
405 const_user_iterator user_end() const { return const_user_iterator(); }
406 User *user_back() {
407 assertModuleIsMaterialized();
408 return *materialized_user_begin();
409 }
410 const User *user_back() const {
411 assertModuleIsMaterialized();
412 return *materialized_user_begin();
413 }
414 iterator_range<user_iterator> materialized_users() {
415 return make_range(materialized_user_begin(), user_end());
416 }
417 iterator_range<const_user_iterator> materialized_users() const {
418 return make_range(materialized_user_begin(), user_end());
419 }
420 iterator_range<user_iterator> users() {
421 assertModuleIsMaterialized();
422 return materialized_users();
423 }
424 iterator_range<const_user_iterator> users() const {
425 assertModuleIsMaterialized();
426 return materialized_users();
427 }
428
429 /// Return true if there is exactly one use of this value.
430 ///
431 /// This is specialized because it is a common request and does not require
432 /// traversing the whole use list.
433 bool hasOneUse() const {
434 const_use_iterator I = use_begin(), E = use_end();
435 if (I == E) return false;
436 return ++I == E;
437 }
438
439 /// Return true if this Value has exactly N uses.
440 bool hasNUses(unsigned N) const;
441
442 /// Return true if this value has N uses or more.
443 ///
444 /// This is logically equivalent to getNumUses() >= N.
445 bool hasNUsesOrMore(unsigned N) const;
446
447 /// Return true if there is exactly one user of this value.
448 ///
449 /// Note that this is not the same as "has one use". If a value has one use,
450 /// then there certainly is a single user. But if value has several uses,
451 /// it is possible that all uses are in a single user, or not.
452 ///
453 /// This check is potentially costly, since it requires traversing,
454 /// in the worst case, the whole use list of a value.
455 bool hasOneUser() const;
456
457 /// Return true if there is exactly one use of this value that cannot be
458 /// dropped.
459 ///
460 /// This is specialized because it is a common request and does not require
461 /// traversing the whole use list.
462 Use *getSingleUndroppableUse();
463
464 /// Return true if there this value.
465 ///
466 /// This is specialized because it is a common request and does not require
467 /// traversing the whole use list.
468 bool hasNUndroppableUses(unsigned N) const;
469
470 /// Return true if this value has N uses or more.
471 ///
472 /// This is logically equivalent to getNumUses() >= N.
473 bool hasNUndroppableUsesOrMore(unsigned N) const;
474
475 /// Remove every uses that can safely be removed.
476 ///
477 /// This will remove for example uses in llvm.assume.
478 /// This should be used when performing want to perform a tranformation but
479 /// some Droppable uses pervent it.
480 /// This function optionally takes a filter to only remove some droppable
481 /// uses.
482 void dropDroppableUses(llvm::function_ref<bool(const Use *)> ShouldDrop =
483 [](const Use *) { return true; });
484
485 /// Remove every use of this value in \p User that can safely be removed.
486 void dropDroppableUsesIn(User &Usr);
487
488 /// Remove the droppable use \p U.
489 static void dropDroppableUse(Use &U);
490
491 /// Check if this value is used in the specified basic block.
492 bool isUsedInBasicBlock(const BasicBlock *BB) const;
493
494 /// This method computes the number of uses of this Value.
495 ///
496 /// This is a linear time operation. Use hasOneUse, hasNUses, or
497 /// hasNUsesOrMore to check for specific values.
498 unsigned getNumUses() const;
499
500 /// This method should only be used by the Use class.
501 void addUse(Use &U) { U.addToList(&UseList); }
502
503 /// Concrete subclass of this.
504 ///
505 /// An enumeration for keeping track of the concrete subclass of Value that
506 /// is actually instantiated. Values of this enumeration are kept in the
507 /// Value classes SubclassID field. They are used for concrete type
508 /// identification.
509 enum ValueTy {
510#define HANDLE_VALUE(Name) Name##Val,
511#include "llvm/IR/Value.def"
512
513 // Markers:
514#define HANDLE_CONSTANT_MARKER(Marker, Constant) Marker = Constant##Val,
515#include "llvm/IR/Value.def"
516 };
517
518 /// Return an ID for the concrete type of this object.
519 ///
520 /// This is used to implement the classof checks. This should not be used
521 /// for any other purpose, as the values may change as LLVM evolves. Also,
522 /// note that for instructions, the Instruction's opcode is added to
523 /// InstructionVal. So this means three things:
524 /// # there is no value with code InstructionVal (no opcode==0).
525 /// # there are more possible values for the value type than in ValueTy enum.
526 /// # the InstructionVal enumerator must be the highest valued enumerator in
527 /// the ValueTy enum.
528 unsigned getValueID() const {
529 return SubclassID;
530 }
531
532 /// Return the raw optional flags value contained in this value.
533 ///
534 /// This should only be used when testing two Values for equivalence.
535 unsigned getRawSubclassOptionalData() const {
536 return SubclassOptionalData;
537 }
538
539 /// Clear the optional flags contained in this value.
540 void clearSubclassOptionalData() {
541 SubclassOptionalData = 0;
542 }
543
544 /// Check the optional flags for equality.
545 bool hasSameSubclassOptionalData(const Value *V) const {
546 return SubclassOptionalData == V->SubclassOptionalData;
547 }
548
549 /// Return true if there is a value handle associated with this value.
550 bool hasValueHandle() const { return HasValueHandle; }
551
552 /// Return true if there is metadata referencing this value.
553 bool isUsedByMetadata() const { return IsUsedByMD; }
554
555protected:
556 /// Get the current metadata attachments for the given kind, if any.
557 ///
558 /// These functions require that the value have at most a single attachment
559 /// of the given kind, and return \c nullptr if such an attachment is missing.
560 /// @{
561 MDNode *getMetadata(unsigned KindID) const;
562 MDNode *getMetadata(StringRef Kind) const;
563 /// @}
564
565 /// Appends all attachments with the given ID to \c MDs in insertion order.
566 /// If the Value has no attachments with the given ID, or if ID is invalid,
567 /// leaves MDs unchanged.
568 /// @{
569 void getMetadata(unsigned KindID, SmallVectorImpl<MDNode *> &MDs) const;
570 void getMetadata(StringRef Kind, SmallVectorImpl<MDNode *> &MDs) const;
571 /// @}
572
573 /// Appends all metadata attached to this value to \c MDs, sorting by
574 /// KindID. The first element of each pair returned is the KindID, the second
575 /// element is the metadata value. Attachments with the same ID appear in
576 /// insertion order.
577 void
578 getAllMetadata(SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const;
579
580 /// Return true if this value has any metadata attached to it.
581 bool hasMetadata() const { return (bool)HasMetadata; }
582
583 /// Return true if this value has the given type of metadata attached.
584 /// @{
585 bool hasMetadata(unsigned KindID) const {
586 return getMetadata(KindID) != nullptr;
587 }
588 bool hasMetadata(StringRef Kind) const {
589 return getMetadata(Kind) != nullptr;
590 }
591 /// @}
592
593 /// Set a particular kind of metadata attachment.
594 ///
595 /// Sets the given attachment to \c MD, erasing it if \c MD is \c nullptr or
596 /// replacing it if it already exists.
597 /// @{
598 void setMetadata(unsigned KindID, MDNode *Node);
599 void setMetadata(StringRef Kind, MDNode *Node);
600 /// @}
601
602 /// Add a metadata attachment.
603 /// @{
604 void addMetadata(unsigned KindID, MDNode &MD);
605 void addMetadata(StringRef Kind, MDNode &MD);
606 /// @}
607
608 /// Erase all metadata attachments with the given kind.
609 ///
610 /// \returns true if any metadata was removed.
611 bool eraseMetadata(unsigned KindID);
612
613 /// Erase all metadata attached to this Value.
614 void clearMetadata();
615
616public:
617 /// Return true if this value is a swifterror value.
618 ///
619 /// swifterror values can be either a function argument or an alloca with a
620 /// swifterror attribute.
621 bool isSwiftError() const;
622
623 /// Strip off pointer casts, all-zero GEPs and address space casts.
624 ///
625 /// Returns the original uncasted value. If this is called on a non-pointer
626 /// value, it returns 'this'.
627 const Value *stripPointerCasts() const;
628 Value *stripPointerCasts() {
629 return const_cast<Value *>(
630 static_cast<const Value *>(this)->stripPointerCasts());
631 }
632
633 /// Strip off pointer casts, all-zero GEPs, address space casts, and aliases.
634 ///
635 /// Returns the original uncasted value. If this is called on a non-pointer
636 /// value, it returns 'this'.
637 const Value *stripPointerCastsAndAliases() const;
638 Value *stripPointerCastsAndAliases() {
639 return const_cast<Value *>(
640 static_cast<const Value *>(this)->stripPointerCastsAndAliases());
641 }
642
643 /// Strip off pointer casts, all-zero GEPs and address space casts
644 /// but ensures the representation of the result stays the same.
645 ///
646 /// Returns the original uncasted value with the same representation. If this
647 /// is called on a non-pointer value, it returns 'this'.
648 const Value *stripPointerCastsSameRepresentation() const;
649 Value *stripPointerCastsSameRepresentation() {
650 return const_cast<Value *>(static_cast<const Value *>(this)
651 ->stripPointerCastsSameRepresentation());
652 }
653
654 /// Strip off pointer casts, all-zero GEPs and invariant group info.
655 ///
656 /// Returns the original uncasted value. If this is called on a non-pointer
657 /// value, it returns 'this'. This function should be used only in
658 /// Alias analysis.
659 const Value *stripPointerCastsAndInvariantGroups() const;
660 Value *stripPointerCastsAndInvariantGroups() {
661 return const_cast<Value *>(static_cast<const Value *>(this)
662 ->stripPointerCastsAndInvariantGroups());
663 }
664
665 /// Strip off pointer casts and all-constant inbounds GEPs.
666 ///
667 /// Returns the original pointer value. If this is called on a non-pointer
668 /// value, it returns 'this'.
669 const Value *stripInBoundsConstantOffsets() const;
670 Value *stripInBoundsConstantOffsets() {
671 return const_cast<Value *>(
672 static_cast<const Value *>(this)->stripInBoundsConstantOffsets());
673 }
674
675 /// Accumulate the constant offset this value has compared to a base pointer.
676 /// Only 'getelementptr' instructions (GEPs) are accumulated but other
677 /// instructions, e.g., casts, are stripped away as well.
678 /// The accumulated constant offset is added to \p Offset and the base
679 /// pointer is returned.
680 ///
681 /// The APInt \p Offset has to have a bit-width equal to the IntPtr type for
682 /// the address space of 'this' pointer value, e.g., use
683 /// DataLayout::getIndexTypeSizeInBits(Ty).
684 ///
685 /// If \p AllowNonInbounds is true, offsets in GEPs are stripped and
686 /// accumulated even if the GEP is not "inbounds".
687 ///
688 /// If \p ExternalAnalysis is provided it will be used to calculate a offset
689 /// when a operand of GEP is not constant.
690 /// For example, for a value \p ExternalAnalysis might try to calculate a
691 /// lower bound. If \p ExternalAnalysis is successful, it should return true.
692 ///
693 /// If this is called on a non-pointer value, it returns 'this' and the
694 /// \p Offset is not modified.
695 ///
696 /// Note that this function will never return a nullptr. It will also never
697 /// manipulate the \p Offset in a way that would not match the difference
698 /// between the underlying value and the returned one. Thus, if no constant
699 /// offset was found, the returned value is the underlying one and \p Offset
700 /// is unchanged.
701 const Value *stripAndAccumulateConstantOffsets(
702 const DataLayout &DL, APInt &Offset, bool AllowNonInbounds,
703 function_ref<bool(Value &Value, APInt &Offset)> ExternalAnalysis =
704 nullptr) const;
705 Value *stripAndAccumulateConstantOffsets(const DataLayout &DL, APInt &Offset,
706 bool AllowNonInbounds) {
707 return const_cast<Value *>(
708 static_cast<const Value *>(this)->stripAndAccumulateConstantOffsets(
709 DL, Offset, AllowNonInbounds));
710 }
711
712 /// This is a wrapper around stripAndAccumulateConstantOffsets with the
713 /// in-bounds requirement set to false.
714 const Value *stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
715 APInt &Offset) const {
716 return stripAndAccumulateConstantOffsets(DL, Offset,
717 /* AllowNonInbounds */ false);
718 }
719 Value *stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
720 APInt &Offset) {
721 return stripAndAccumulateConstantOffsets(DL, Offset,
722 /* AllowNonInbounds */ false);
723 }
724
725 /// Strip off pointer casts and inbounds GEPs.
726 ///
727 /// Returns the original pointer value. If this is called on a non-pointer
728 /// value, it returns 'this'.
729 const Value *stripInBoundsOffsets(function_ref<void(const Value *)> Func =
730 [](const Value *) {}) const;
731 inline Value *stripInBoundsOffsets(function_ref<void(const Value *)> Func =
732 [](const Value *) {}) {
733 return const_cast<Value *>(
734 static_cast<const Value *>(this)->stripInBoundsOffsets(Func));
735 }
736
737 /// Returns the number of bytes known to be dereferenceable for the
738 /// pointer value.
739 ///
740 /// If CanBeNull is set by this function the pointer can either be null or be
741 /// dereferenceable up to the returned number of bytes.
742 uint64_t getPointerDereferenceableBytes(const DataLayout &DL,
743 bool &CanBeNull) const;
744
745 /// Returns an alignment of the pointer value.
746 ///
747 /// Returns an alignment which is either specified explicitly, e.g. via
748 /// align attribute of a function argument, or guaranteed by DataLayout.
749 Align getPointerAlignment(const DataLayout &DL) const;
750
751 /// Translate PHI node to its predecessor from the given basic block.
752 ///
753 /// If this value is a PHI node with CurBB as its parent, return the value in
754 /// the PHI node corresponding to PredBB. If not, return ourself. This is
755 /// useful if you want to know the value something has in a predecessor
756 /// block.
757 const Value *DoPHITranslation(const BasicBlock *CurBB,
758 const BasicBlock *PredBB) const;
759 Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB) {
760 return const_cast<Value *>(
761 static_cast<const Value *>(this)->DoPHITranslation(CurBB, PredBB));
762 }
763
764 /// The maximum alignment for instructions.
765 ///
766 /// This is the greatest alignment value supported by load, store, and alloca
767 /// instructions, and global values.
768 static const unsigned MaxAlignmentExponent = 29;
769 static const unsigned MaximumAlignment = 1u << MaxAlignmentExponent;
770
771 /// Mutate the type of this Value to be of the specified type.
772 ///
773 /// Note that this is an extremely dangerous operation which can create
774 /// completely invalid IR very easily. It is strongly recommended that you
775 /// recreate IR objects with the right types instead of mutating them in
776 /// place.
777 void mutateType(Type *Ty) {
778 VTy = Ty;
779 }
780
781 /// Sort the use-list.
782 ///
783 /// Sorts the Value's use-list by Cmp using a stable mergesort. Cmp is
784 /// expected to compare two \a Use references.
785 template <class Compare> void sortUseList(Compare Cmp);
786
787 /// Reverse the use-list.
788 void reverseUseList();
789
790private:
791 /// Merge two lists together.
792 ///
793 /// Merges \c L and \c R using \c Cmp. To enable stable sorts, always pushes
794 /// "equal" items from L before items from R.
795 ///
796 /// \return the first element in the list.
797 ///
798 /// \note Completely ignores \a Use::Prev (doesn't read, doesn't update).
799 template <class Compare>
800 static Use *mergeUseLists(Use *L, Use *R, Compare Cmp) {
801 Use *Merged;
802 Use **Next = &Merged;
803
804 while (true) {
805 if (!L) {
806 *Next = R;
807 break;
808 }
809 if (!R) {
810 *Next = L;
811 break;
812 }
813 if (Cmp(*R, *L)) {
814 *Next = R;
815 Next = &R->Next;
816 R = R->Next;
817 } else {
818 *Next = L;
819 Next = &L->Next;
820 L = L->Next;
821 }
822 }
823
824 return Merged;
825 }
826
827protected:
828 unsigned short getSubclassDataFromValue() const { return SubclassData; }
829 void setValueSubclassData(unsigned short D) { SubclassData = D; }
830};
831
832struct ValueDeleter { void operator()(Value *V) { V->deleteValue(); } };
833
834/// Use this instead of std::unique_ptr<Value> or std::unique_ptr<Instruction>.
835/// Those don't work because Value and Instruction's destructors are protected,
836/// aren't virtual, and won't destroy the complete object.
837using unique_value = std::unique_ptr<Value, ValueDeleter>;
838
839inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) {
840 V.print(OS);
841 return OS;
842}
843
844void Use::set(Value *V) {
845 if (Val) removeFromList();
846 Val = V;
847 if (V) V->addUse(*this);
848}
849
850Value *Use::operator=(Value *RHS) {
851 set(RHS);
852 return RHS;
853}
854
855const Use &Use::operator=(const Use &RHS) {
856 set(RHS.Val);
857 return *this;
858}
859
860template <class Compare> void Value::sortUseList(Compare Cmp) {
861 if (!UseList || !UseList->Next)
862 // No need to sort 0 or 1 uses.
863 return;
864
865 // Note: this function completely ignores Prev pointers until the end when
866 // they're fixed en masse.
867
868 // Create a binomial vector of sorted lists, visiting uses one at a time and
869 // merging lists as necessary.
870 const unsigned MaxSlots = 32;
871 Use *Slots[MaxSlots];
872
873 // Collect the first use, turning it into a single-item list.
874 Use *Next = UseList->Next;
875 UseList->Next = nullptr;
876 unsigned NumSlots = 1;
877 Slots[0] = UseList;
878
879 // Collect all but the last use.
880 while (Next->Next) {
881 Use *Current = Next;
882 Next = Current->Next;
883
884 // Turn Current into a single-item list.
885 Current->Next = nullptr;
886
887 // Save Current in the first available slot, merging on collisions.
888 unsigned I;
889 for (I = 0; I < NumSlots; ++I) {
890 if (!Slots[I])
891 break;
892
893 // Merge two lists, doubling the size of Current and emptying slot I.
894 //
895 // Since the uses in Slots[I] originally preceded those in Current, send
896 // Slots[I] in as the left parameter to maintain a stable sort.
897 Current = mergeUseLists(Slots[I], Current, Cmp);
898 Slots[I] = nullptr;
899 }
900 // Check if this is a new slot.
901 if (I == NumSlots) {
902 ++NumSlots;
903 assert(NumSlots <= MaxSlots && "Use list bigger than 2^32")((NumSlots <= MaxSlots && "Use list bigger than 2^32"
) ? static_cast<void> (0) : __assert_fail ("NumSlots <= MaxSlots && \"Use list bigger than 2^32\""
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/include/llvm/IR/Value.h"
, 903, __PRETTY_FUNCTION__))
;
904 }
905
906 // Found an open slot.
907 Slots[I] = Current;
908 }
909
910 // Merge all the lists together.
911 assert(Next && "Expected one more Use")((Next && "Expected one more Use") ? static_cast<void
> (0) : __assert_fail ("Next && \"Expected one more Use\""
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/include/llvm/IR/Value.h"
, 911, __PRETTY_FUNCTION__))
;
912 assert(!Next->Next && "Expected only one Use")((!Next->Next && "Expected only one Use") ? static_cast
<void> (0) : __assert_fail ("!Next->Next && \"Expected only one Use\""
, "/build/llvm-toolchain-snapshot-12~++20201026111116+d3205bbca3e/llvm/include/llvm/IR/Value.h"
, 912, __PRETTY_FUNCTION__))
;
913 UseList = Next;
914 for (unsigned I = 0; I < NumSlots; ++I)
915 if (Slots[I])
916 // Since the uses in Slots[I] originally preceded those in UseList, send
917 // Slots[I] in as the left parameter to maintain a stable sort.
918 UseList = mergeUseLists(Slots[I], UseList, Cmp);
919
920 // Fix the Prev pointers.
921 for (Use *I = UseList, **Prev = &UseList; I; I = I->Next) {
922 I->Prev = Prev;
923 Prev = &I->Next;
924 }
925}
926
927// isa - Provide some specializations of isa so that we don't have to include
928// the subtype header files to test to see if the value is a subclass...
929//
930template <> struct isa_impl<Constant, Value> {
931 static inline bool doit(const Value &Val) {
932 static_assert(Value::ConstantFirstVal == 0, "Val.getValueID() >= Value::ConstantFirstVal");
933 return Val.getValueID() <= Value::ConstantLastVal;
934 }
935};
936
937template <> struct isa_impl<ConstantData, Value> {
938 static inline bool doit(const Value &Val) {
939 return Val.getValueID() >= Value::ConstantDataFirstVal &&
940 Val.getValueID() <= Value::ConstantDataLastVal;
941 }
942};
943
944template <> struct isa_impl<ConstantAggregate, Value> {
945 static inline bool doit(const Value &Val) {
946 return Val.getValueID() >= Value::ConstantAggregateFirstVal &&
947 Val.getValueID() <= Value::ConstantAggregateLastVal;
948 }
949};
950
951template <> struct isa_impl<Argument, Value> {
952 static inline bool doit (const Value &Val) {
953 return Val.getValueID() == Value::ArgumentVal;
954 }
955};
956
957template <> struct isa_impl<InlineAsm, Value> {
958 static inline bool doit(const Value &Val) {
959 return Val.getValueID() == Value::InlineAsmVal;
960 }
961};
962
963template <> struct isa_impl<Instruction, Value> {
964 static inline bool doit(const Value &Val) {
965 return Val.getValueID() >= Value::InstructionVal;
966 }
967};
968
969template <> struct isa_impl<BasicBlock, Value> {
970 static inline bool doit(const Value &Val) {
971 return Val.getValueID() == Value::BasicBlockVal;
972 }
973};
974
975template <> struct isa_impl<Function, Value> {
976 static inline bool doit(const Value &Val) {
977 return Val.getValueID() == Value::FunctionVal;
978 }
979};
980
981template <> struct isa_impl<GlobalVariable, Value> {
982 static inline bool doit(const Value &Val) {
983 return Val.getValueID() == Value::GlobalVariableVal;
984 }
985};
986
987template <> struct isa_impl<GlobalAlias, Value> {
988 static inline bool doit(const Value &Val) {
989 return Val.getValueID() == Value::GlobalAliasVal;
990 }
991};
992
993template <> struct isa_impl<GlobalIFunc, Value> {
994 static inline bool doit(const Value &Val) {
995 return Val.getValueID() == Value::GlobalIFuncVal;
996 }
997};
998
999template <> struct isa_impl<GlobalIndirectSymbol, Value> {
1000 static inline bool doit(const Value &Val) {
1001 return isa<GlobalAlias>(Val) || isa<GlobalIFunc>(Val);
1002 }
1003};
1004
1005template <> struct isa_impl<GlobalValue, Value> {
1006 static inline bool doit(const Value &Val) {
1007 return isa<GlobalObject>(Val) || isa<GlobalIndirectSymbol>(Val);
1008 }
1009};
1010
1011template <> struct isa_impl<GlobalObject, Value> {
1012 static inline bool doit(const Value &Val) {
1013 return isa<GlobalVariable>(Val) || isa<Function>(Val);
1014 }
1015};
1016
1017// Create wrappers for C Binding types (see CBindingWrapping.h).
1018DEFINE_ISA_CONVERSION_FUNCTIONS(Value, LLVMValueRef)inline Value *unwrap(LLVMValueRef P) { return reinterpret_cast
<Value*>(P); } inline LLVMValueRef wrap(const Value *P)
{ return reinterpret_cast<LLVMValueRef>(const_cast<
Value*>(P)); } template<typename T> inline T *unwrap
(LLVMValueRef P) { return cast<T>(unwrap(P)); }
1019
1020// Specialized opaque value conversions.
1021inline Value **unwrap(LLVMValueRef *Vals) {
1022 return reinterpret_cast<Value**>(Vals);
1023}
1024
1025template<typename T>
1026inline T **unwrap(LLVMValueRef *Vals, unsigned Length) {
1027#ifndef NDEBUG
1028 for (LLVMValueRef *I = Vals, *E = Vals + Length; I != E; ++I)
1029 unwrap<T>(*I); // For side effect of calling assert on invalid usage.
1030#endif
1031 (void)Length;
1032 return reinterpret_cast<T**>(Vals);
1033}
1034
1035inline LLVMValueRef *wrap(const Value **Vals) {
1036 return reinterpret_cast<LLVMValueRef*>(const_cast<Value**>(Vals));
1037}
1038
1039} // end namespace llvm
1040
1041#endif // LLVM_IR_VALUE_H