1 //===- MemProfiler.cpp - memory allocation and access profiler ------------===//
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 is a part of MemProfiler. Memory accesses are instrumented
10 // to increment the access count held in a shadow memory location, or
11 // alternatively to call into the runtime. Memory intrinsic calls (memmove,
12 // memcpy, memset) are changed to call the memory profiling runtime version
13 // instead.
14 //
15 //===----------------------------------------------------------------------===//
16
17 #include "llvm/Transforms/Instrumentation/MemProfiler.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/Statistic.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/Analysis/ValueTracking.h"
23 #include "llvm/IR/Constant.h"
24 #include "llvm/IR/DataLayout.h"
25 #include "llvm/IR/Function.h"
26 #include "llvm/IR/GlobalValue.h"
27 #include "llvm/IR/IRBuilder.h"
28 #include "llvm/IR/Instruction.h"
29 #include "llvm/IR/IntrinsicInst.h"
30 #include "llvm/IR/Module.h"
31 #include "llvm/IR/Type.h"
32 #include "llvm/IR/Value.h"
33 #include "llvm/InitializePasses.h"
34 #include "llvm/Pass.h"
35 #include "llvm/ProfileData/InstrProf.h"
36 #include "llvm/Support/CommandLine.h"
37 #include "llvm/Support/Debug.h"
38 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
39 #include "llvm/Transforms/Utils/ModuleUtils.h"
40
41 using namespace llvm;
42
43 #define DEBUG_TYPE "memprof"
44
45 constexpr int LLVM_MEM_PROFILER_VERSION = 1;
46
47 // Size of memory mapped to a single shadow location.
48 constexpr uint64_t DefaultShadowGranularity = 64;
49
50 // Scale from granularity down to shadow size.
51 constexpr uint64_t DefaultShadowScale = 3;
52
53 constexpr char MemProfModuleCtorName[] = "memprof.module_ctor";
54 constexpr uint64_t MemProfCtorAndDtorPriority = 1;
55 // On Emscripten, the system needs more than one priorities for constructors.
56 constexpr uint64_t MemProfEmscriptenCtorAndDtorPriority = 50;
57 constexpr char MemProfInitName[] = "__memprof_init";
58 constexpr char MemProfVersionCheckNamePrefix[] =
59 "__memprof_version_mismatch_check_v";
60
61 constexpr char MemProfShadowMemoryDynamicAddress[] =
62 "__memprof_shadow_memory_dynamic_address";
63
64 constexpr char MemProfFilenameVar[] = "__memprof_profile_filename";
65
66 // Command-line flags.
67
68 static cl::opt<bool> ClInsertVersionCheck(
69 "memprof-guard-against-version-mismatch",
70 cl::desc("Guard against compiler/runtime version mismatch."), cl::Hidden,
71 cl::init(true));
72
73 // This flag may need to be replaced with -f[no-]memprof-reads.
74 static cl::opt<bool> ClInstrumentReads("memprof-instrument-reads",
75 cl::desc("instrument read instructions"),
76 cl::Hidden, cl::init(true));
77
78 static cl::opt<bool>
79 ClInstrumentWrites("memprof-instrument-writes",
80 cl::desc("instrument write instructions"), cl::Hidden,
81 cl::init(true));
82
83 static cl::opt<bool> ClInstrumentAtomics(
84 "memprof-instrument-atomics",
85 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
86 cl::init(true));
87
88 static cl::opt<bool> ClUseCalls(
89 "memprof-use-callbacks",
90 cl::desc("Use callbacks instead of inline instrumentation sequences."),
91 cl::Hidden, cl::init(false));
92
93 static cl::opt<std::string>
94 ClMemoryAccessCallbackPrefix("memprof-memory-access-callback-prefix",
95 cl::desc("Prefix for memory access callbacks"),
96 cl::Hidden, cl::init("__memprof_"));
97
98 // These flags allow to change the shadow mapping.
99 // The shadow mapping looks like
100 // Shadow = ((Mem & mask) >> scale) + offset
101
102 static cl::opt<int> ClMappingScale("memprof-mapping-scale",
103 cl::desc("scale of memprof shadow mapping"),
104 cl::Hidden, cl::init(DefaultShadowScale));
105
106 static cl::opt<int>
107 ClMappingGranularity("memprof-mapping-granularity",
108 cl::desc("granularity of memprof shadow mapping"),
109 cl::Hidden, cl::init(DefaultShadowGranularity));
110
111 static cl::opt<bool> ClStack("memprof-instrument-stack",
112 cl::desc("Instrument scalar stack variables"),
113 cl::Hidden, cl::init(false));
114
115 // Debug flags.
116
117 static cl::opt<int> ClDebug("memprof-debug", cl::desc("debug"), cl::Hidden,
118 cl::init(0));
119
120 static cl::opt<std::string> ClDebugFunc("memprof-debug-func", cl::Hidden,
121 cl::desc("Debug func"));
122
123 static cl::opt<int> ClDebugMin("memprof-debug-min", cl::desc("Debug min inst"),
124 cl::Hidden, cl::init(-1));
125
126 static cl::opt<int> ClDebugMax("memprof-debug-max", cl::desc("Debug max inst"),
127 cl::Hidden, cl::init(-1));
128
129 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
130 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
131 STATISTIC(NumSkippedStackReads, "Number of non-instrumented stack reads");
132 STATISTIC(NumSkippedStackWrites, "Number of non-instrumented stack writes");
133
134 namespace {
135
136 /// This struct defines the shadow mapping using the rule:
137 /// shadow = ((mem & mask) >> Scale) ADD DynamicShadowOffset.
138 struct ShadowMapping {
ShadowMapping__anon4e56afe00111::ShadowMapping139 ShadowMapping() {
140 Scale = ClMappingScale;
141 Granularity = ClMappingGranularity;
142 Mask = ~(Granularity - 1);
143 }
144
145 int Scale;
146 int Granularity;
147 uint64_t Mask; // Computed as ~(Granularity-1)
148 };
149
getCtorAndDtorPriority(Triple & TargetTriple)150 static uint64_t getCtorAndDtorPriority(Triple &TargetTriple) {
151 return TargetTriple.isOSEmscripten() ? MemProfEmscriptenCtorAndDtorPriority
152 : MemProfCtorAndDtorPriority;
153 }
154
155 struct InterestingMemoryAccess {
156 Value *Addr = nullptr;
157 bool IsWrite;
158 Type *AccessTy;
159 uint64_t TypeSize;
160 Value *MaybeMask = nullptr;
161 };
162
163 /// Instrument the code in module to profile memory accesses.
164 class MemProfiler {
165 public:
MemProfiler(Module & M)166 MemProfiler(Module &M) {
167 C = &(M.getContext());
168 LongSize = M.getDataLayout().getPointerSizeInBits();
169 IntptrTy = Type::getIntNTy(*C, LongSize);
170 }
171
172 /// If it is an interesting memory access, populate information
173 /// about the access and return a InterestingMemoryAccess struct.
174 /// Otherwise return std::nullopt.
175 std::optional<InterestingMemoryAccess>
176 isInterestingMemoryAccess(Instruction *I) const;
177
178 void instrumentMop(Instruction *I, const DataLayout &DL,
179 InterestingMemoryAccess &Access);
180 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
181 Value *Addr, uint32_t TypeSize, bool IsWrite);
182 void instrumentMaskedLoadOrStore(const DataLayout &DL, Value *Mask,
183 Instruction *I, Value *Addr, Type *AccessTy,
184 bool IsWrite);
185 void instrumentMemIntrinsic(MemIntrinsic *MI);
186 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
187 bool instrumentFunction(Function &F);
188 bool maybeInsertMemProfInitAtFunctionEntry(Function &F);
189 bool insertDynamicShadowAtFunctionEntry(Function &F);
190
191 private:
192 void initializeCallbacks(Module &M);
193
194 LLVMContext *C;
195 int LongSize;
196 Type *IntptrTy;
197 ShadowMapping Mapping;
198
199 // These arrays is indexed by AccessIsWrite
200 FunctionCallee MemProfMemoryAccessCallback[2];
201 FunctionCallee MemProfMemoryAccessCallbackSized[2];
202
203 FunctionCallee MemProfMemmove, MemProfMemcpy, MemProfMemset;
204 Value *DynamicShadowOffset = nullptr;
205 };
206
207 class ModuleMemProfiler {
208 public:
ModuleMemProfiler(Module & M)209 ModuleMemProfiler(Module &M) { TargetTriple = Triple(M.getTargetTriple()); }
210
211 bool instrumentModule(Module &);
212
213 private:
214 Triple TargetTriple;
215 ShadowMapping Mapping;
216 Function *MemProfCtorFunction = nullptr;
217 };
218
219 } // end anonymous namespace
220
221 MemProfilerPass::MemProfilerPass() = default;
222
run(Function & F,AnalysisManager<Function> & AM)223 PreservedAnalyses MemProfilerPass::run(Function &F,
224 AnalysisManager<Function> &AM) {
225 Module &M = *F.getParent();
226 MemProfiler Profiler(M);
227 if (Profiler.instrumentFunction(F))
228 return PreservedAnalyses::none();
229 return PreservedAnalyses::all();
230 }
231
232 ModuleMemProfilerPass::ModuleMemProfilerPass() = default;
233
run(Module & M,AnalysisManager<Module> & AM)234 PreservedAnalyses ModuleMemProfilerPass::run(Module &M,
235 AnalysisManager<Module> &AM) {
236 ModuleMemProfiler Profiler(M);
237 if (Profiler.instrumentModule(M))
238 return PreservedAnalyses::none();
239 return PreservedAnalyses::all();
240 }
241
memToShadow(Value * Shadow,IRBuilder<> & IRB)242 Value *MemProfiler::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
243 // (Shadow & mask) >> scale
244 Shadow = IRB.CreateAnd(Shadow, Mapping.Mask);
245 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
246 // (Shadow >> scale) | offset
247 assert(DynamicShadowOffset);
248 return IRB.CreateAdd(Shadow, DynamicShadowOffset);
249 }
250
251 // Instrument memset/memmove/memcpy
instrumentMemIntrinsic(MemIntrinsic * MI)252 void MemProfiler::instrumentMemIntrinsic(MemIntrinsic *MI) {
253 IRBuilder<> IRB(MI);
254 if (isa<MemTransferInst>(MI)) {
255 IRB.CreateCall(
256 isa<MemMoveInst>(MI) ? MemProfMemmove : MemProfMemcpy,
257 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
258 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
259 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
260 } else if (isa<MemSetInst>(MI)) {
261 IRB.CreateCall(
262 MemProfMemset,
263 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
264 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
265 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
266 }
267 MI->eraseFromParent();
268 }
269
270 std::optional<InterestingMemoryAccess>
isInterestingMemoryAccess(Instruction * I) const271 MemProfiler::isInterestingMemoryAccess(Instruction *I) const {
272 // Do not instrument the load fetching the dynamic shadow address.
273 if (DynamicShadowOffset == I)
274 return std::nullopt;
275
276 InterestingMemoryAccess Access;
277
278 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
279 if (!ClInstrumentReads)
280 return std::nullopt;
281 Access.IsWrite = false;
282 Access.AccessTy = LI->getType();
283 Access.Addr = LI->getPointerOperand();
284 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
285 if (!ClInstrumentWrites)
286 return std::nullopt;
287 Access.IsWrite = true;
288 Access.AccessTy = SI->getValueOperand()->getType();
289 Access.Addr = SI->getPointerOperand();
290 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
291 if (!ClInstrumentAtomics)
292 return std::nullopt;
293 Access.IsWrite = true;
294 Access.AccessTy = RMW->getValOperand()->getType();
295 Access.Addr = RMW->getPointerOperand();
296 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
297 if (!ClInstrumentAtomics)
298 return std::nullopt;
299 Access.IsWrite = true;
300 Access.AccessTy = XCHG->getCompareOperand()->getType();
301 Access.Addr = XCHG->getPointerOperand();
302 } else if (auto *CI = dyn_cast<CallInst>(I)) {
303 auto *F = CI->getCalledFunction();
304 if (F && (F->getIntrinsicID() == Intrinsic::masked_load ||
305 F->getIntrinsicID() == Intrinsic::masked_store)) {
306 unsigned OpOffset = 0;
307 if (F->getIntrinsicID() == Intrinsic::masked_store) {
308 if (!ClInstrumentWrites)
309 return std::nullopt;
310 // Masked store has an initial operand for the value.
311 OpOffset = 1;
312 Access.AccessTy = CI->getArgOperand(0)->getType();
313 Access.IsWrite = true;
314 } else {
315 if (!ClInstrumentReads)
316 return std::nullopt;
317 Access.AccessTy = CI->getType();
318 Access.IsWrite = false;
319 }
320
321 auto *BasePtr = CI->getOperand(0 + OpOffset);
322 Access.MaybeMask = CI->getOperand(2 + OpOffset);
323 Access.Addr = BasePtr;
324 }
325 }
326
327 if (!Access.Addr)
328 return std::nullopt;
329
330 // Do not instrument accesses from different address spaces; we cannot deal
331 // with them.
332 Type *PtrTy = cast<PointerType>(Access.Addr->getType()->getScalarType());
333 if (PtrTy->getPointerAddressSpace() != 0)
334 return std::nullopt;
335
336 // Ignore swifterror addresses.
337 // swifterror memory addresses are mem2reg promoted by instruction
338 // selection. As such they cannot have regular uses like an instrumentation
339 // function and it makes no sense to track them as memory.
340 if (Access.Addr->isSwiftError())
341 return std::nullopt;
342
343 // Peel off GEPs and BitCasts.
344 auto *Addr = Access.Addr->stripInBoundsOffsets();
345
346 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
347 // Do not instrument PGO counter updates.
348 if (GV->hasSection()) {
349 StringRef SectionName = GV->getSection();
350 // Check if the global is in the PGO counters section.
351 auto OF = Triple(I->getModule()->getTargetTriple()).getObjectFormat();
352 if (SectionName.endswith(
353 getInstrProfSectionName(IPSK_cnts, OF, /*AddSegmentInfo=*/false)))
354 return std::nullopt;
355 }
356
357 // Do not instrument accesses to LLVM internal variables.
358 if (GV->getName().startswith("__llvm"))
359 return std::nullopt;
360 }
361
362 const DataLayout &DL = I->getModule()->getDataLayout();
363 Access.TypeSize = DL.getTypeStoreSizeInBits(Access.AccessTy);
364 return Access;
365 }
366
instrumentMaskedLoadOrStore(const DataLayout & DL,Value * Mask,Instruction * I,Value * Addr,Type * AccessTy,bool IsWrite)367 void MemProfiler::instrumentMaskedLoadOrStore(const DataLayout &DL, Value *Mask,
368 Instruction *I, Value *Addr,
369 Type *AccessTy, bool IsWrite) {
370 auto *VTy = cast<FixedVectorType>(AccessTy);
371 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
372 unsigned Num = VTy->getNumElements();
373 auto *Zero = ConstantInt::get(IntptrTy, 0);
374 for (unsigned Idx = 0; Idx < Num; ++Idx) {
375 Value *InstrumentedAddress = nullptr;
376 Instruction *InsertBefore = I;
377 if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
378 // dyn_cast as we might get UndefValue
379 if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
380 if (Masked->isZero())
381 // Mask is constant false, so no instrumentation needed.
382 continue;
383 // If we have a true or undef value, fall through to instrumentAddress.
384 // with InsertBefore == I
385 }
386 } else {
387 IRBuilder<> IRB(I);
388 Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
389 Instruction *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
390 InsertBefore = ThenTerm;
391 }
392
393 IRBuilder<> IRB(InsertBefore);
394 InstrumentedAddress =
395 IRB.CreateGEP(VTy, Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
396 instrumentAddress(I, InsertBefore, InstrumentedAddress, ElemTypeSize,
397 IsWrite);
398 }
399 }
400
instrumentMop(Instruction * I,const DataLayout & DL,InterestingMemoryAccess & Access)401 void MemProfiler::instrumentMop(Instruction *I, const DataLayout &DL,
402 InterestingMemoryAccess &Access) {
403 // Skip instrumentation of stack accesses unless requested.
404 if (!ClStack && isa<AllocaInst>(getUnderlyingObject(Access.Addr))) {
405 if (Access.IsWrite)
406 ++NumSkippedStackWrites;
407 else
408 ++NumSkippedStackReads;
409 return;
410 }
411
412 if (Access.IsWrite)
413 NumInstrumentedWrites++;
414 else
415 NumInstrumentedReads++;
416
417 if (Access.MaybeMask) {
418 instrumentMaskedLoadOrStore(DL, Access.MaybeMask, I, Access.Addr,
419 Access.AccessTy, Access.IsWrite);
420 } else {
421 // Since the access counts will be accumulated across the entire allocation,
422 // we only update the shadow access count for the first location and thus
423 // don't need to worry about alignment and type size.
424 instrumentAddress(I, I, Access.Addr, Access.TypeSize, Access.IsWrite);
425 }
426 }
427
instrumentAddress(Instruction * OrigIns,Instruction * InsertBefore,Value * Addr,uint32_t TypeSize,bool IsWrite)428 void MemProfiler::instrumentAddress(Instruction *OrigIns,
429 Instruction *InsertBefore, Value *Addr,
430 uint32_t TypeSize, bool IsWrite) {
431 IRBuilder<> IRB(InsertBefore);
432 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
433
434 if (ClUseCalls) {
435 IRB.CreateCall(MemProfMemoryAccessCallback[IsWrite], AddrLong);
436 return;
437 }
438
439 // Create an inline sequence to compute shadow location, and increment the
440 // value by one.
441 Type *ShadowTy = Type::getInt64Ty(*C);
442 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
443 Value *ShadowPtr = memToShadow(AddrLong, IRB);
444 Value *ShadowAddr = IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy);
445 Value *ShadowValue = IRB.CreateLoad(ShadowTy, ShadowAddr);
446 Value *Inc = ConstantInt::get(Type::getInt64Ty(*C), 1);
447 ShadowValue = IRB.CreateAdd(ShadowValue, Inc);
448 IRB.CreateStore(ShadowValue, ShadowAddr);
449 }
450
451 // Create the variable for the profile file name.
createProfileFileNameVar(Module & M)452 void createProfileFileNameVar(Module &M) {
453 const MDString *MemProfFilename =
454 dyn_cast_or_null<MDString>(M.getModuleFlag("MemProfProfileFilename"));
455 if (!MemProfFilename)
456 return;
457 assert(!MemProfFilename->getString().empty() &&
458 "Unexpected MemProfProfileFilename metadata with empty string");
459 Constant *ProfileNameConst = ConstantDataArray::getString(
460 M.getContext(), MemProfFilename->getString(), true);
461 GlobalVariable *ProfileNameVar = new GlobalVariable(
462 M, ProfileNameConst->getType(), /*isConstant=*/true,
463 GlobalValue::WeakAnyLinkage, ProfileNameConst, MemProfFilenameVar);
464 Triple TT(M.getTargetTriple());
465 if (TT.supportsCOMDAT()) {
466 ProfileNameVar->setLinkage(GlobalValue::ExternalLinkage);
467 ProfileNameVar->setComdat(M.getOrInsertComdat(MemProfFilenameVar));
468 }
469 }
470
instrumentModule(Module & M)471 bool ModuleMemProfiler::instrumentModule(Module &M) {
472 // Create a module constructor.
473 std::string MemProfVersion = std::to_string(LLVM_MEM_PROFILER_VERSION);
474 std::string VersionCheckName =
475 ClInsertVersionCheck ? (MemProfVersionCheckNamePrefix + MemProfVersion)
476 : "";
477 std::tie(MemProfCtorFunction, std::ignore) =
478 createSanitizerCtorAndInitFunctions(M, MemProfModuleCtorName,
479 MemProfInitName, /*InitArgTypes=*/{},
480 /*InitArgs=*/{}, VersionCheckName);
481
482 const uint64_t Priority = getCtorAndDtorPriority(TargetTriple);
483 appendToGlobalCtors(M, MemProfCtorFunction, Priority);
484
485 createProfileFileNameVar(M);
486
487 return true;
488 }
489
initializeCallbacks(Module & M)490 void MemProfiler::initializeCallbacks(Module &M) {
491 IRBuilder<> IRB(*C);
492
493 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
494 const std::string TypeStr = AccessIsWrite ? "store" : "load";
495
496 SmallVector<Type *, 3> Args2 = {IntptrTy, IntptrTy};
497 SmallVector<Type *, 2> Args1{1, IntptrTy};
498 MemProfMemoryAccessCallbackSized[AccessIsWrite] =
499 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + TypeStr + "N",
500 FunctionType::get(IRB.getVoidTy(), Args2, false));
501
502 MemProfMemoryAccessCallback[AccessIsWrite] =
503 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + TypeStr,
504 FunctionType::get(IRB.getVoidTy(), Args1, false));
505 }
506 MemProfMemmove = M.getOrInsertFunction(
507 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
508 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy);
509 MemProfMemcpy = M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "memcpy",
510 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
511 IRB.getInt8PtrTy(), IntptrTy);
512 MemProfMemset = M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "memset",
513 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
514 IRB.getInt32Ty(), IntptrTy);
515 }
516
maybeInsertMemProfInitAtFunctionEntry(Function & F)517 bool MemProfiler::maybeInsertMemProfInitAtFunctionEntry(Function &F) {
518 // For each NSObject descendant having a +load method, this method is invoked
519 // by the ObjC runtime before any of the static constructors is called.
520 // Therefore we need to instrument such methods with a call to __memprof_init
521 // at the beginning in order to initialize our runtime before any access to
522 // the shadow memory.
523 // We cannot just ignore these methods, because they may call other
524 // instrumented functions.
525 if (F.getName().find(" load]") != std::string::npos) {
526 FunctionCallee MemProfInitFunction =
527 declareSanitizerInitFunction(*F.getParent(), MemProfInitName, {});
528 IRBuilder<> IRB(&F.front(), F.front().begin());
529 IRB.CreateCall(MemProfInitFunction, {});
530 return true;
531 }
532 return false;
533 }
534
insertDynamicShadowAtFunctionEntry(Function & F)535 bool MemProfiler::insertDynamicShadowAtFunctionEntry(Function &F) {
536 IRBuilder<> IRB(&F.front().front());
537 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
538 MemProfShadowMemoryDynamicAddress, IntptrTy);
539 if (F.getParent()->getPICLevel() == PICLevel::NotPIC)
540 cast<GlobalVariable>(GlobalDynamicAddress)->setDSOLocal(true);
541 DynamicShadowOffset = IRB.CreateLoad(IntptrTy, GlobalDynamicAddress);
542 return true;
543 }
544
instrumentFunction(Function & F)545 bool MemProfiler::instrumentFunction(Function &F) {
546 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
547 return false;
548 if (ClDebugFunc == F.getName())
549 return false;
550 if (F.getName().startswith("__memprof_"))
551 return false;
552
553 bool FunctionModified = false;
554
555 // If needed, insert __memprof_init.
556 // This function needs to be called even if the function body is not
557 // instrumented.
558 if (maybeInsertMemProfInitAtFunctionEntry(F))
559 FunctionModified = true;
560
561 LLVM_DEBUG(dbgs() << "MEMPROF instrumenting:\n" << F << "\n");
562
563 initializeCallbacks(*F.getParent());
564
565 SmallVector<Instruction *, 16> ToInstrument;
566
567 // Fill the set of memory operations to instrument.
568 for (auto &BB : F) {
569 for (auto &Inst : BB) {
570 if (isInterestingMemoryAccess(&Inst) || isa<MemIntrinsic>(Inst))
571 ToInstrument.push_back(&Inst);
572 }
573 }
574
575 if (ToInstrument.empty()) {
576 LLVM_DEBUG(dbgs() << "MEMPROF done instrumenting: " << FunctionModified
577 << " " << F << "\n");
578
579 return FunctionModified;
580 }
581
582 FunctionModified |= insertDynamicShadowAtFunctionEntry(F);
583
584 int NumInstrumented = 0;
585 for (auto *Inst : ToInstrument) {
586 if (ClDebugMin < 0 || ClDebugMax < 0 ||
587 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
588 std::optional<InterestingMemoryAccess> Access =
589 isInterestingMemoryAccess(Inst);
590 if (Access)
591 instrumentMop(Inst, F.getParent()->getDataLayout(), *Access);
592 else
593 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
594 }
595 NumInstrumented++;
596 }
597
598 if (NumInstrumented > 0)
599 FunctionModified = true;
600
601 LLVM_DEBUG(dbgs() << "MEMPROF done instrumenting: " << FunctionModified << " "
602 << F << "\n");
603
604 return FunctionModified;
605 }
606