1 //=-- InstrProf.cpp - Instrumented profiling format support -----------------=//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains support for clang's instrumentation based PGO and
11 // coverage.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/IR/Constants.h"
16 #include "llvm/IR/Function.h"
17 #include "llvm/IR/Module.h"
18 #include "llvm/IR/GlobalVariable.h"
19 #include "llvm/ProfileData/InstrProf.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "llvm/Support/ManagedStatic.h"
22 
23 using namespace llvm;
24 
25 namespace {
26 class InstrProfErrorCategoryType : public std::error_category {
27   const char *name() const LLVM_NOEXCEPT override { return "llvm.instrprof"; }
28   std::string message(int IE) const override {
29     instrprof_error E = static_cast<instrprof_error>(IE);
30     switch (E) {
31     case instrprof_error::success:
32       return "Success";
33     case instrprof_error::eof:
34       return "End of File";
35     case instrprof_error::unrecognized_format:
36       return "Unrecognized instrumentation profile encoding format";
37     case instrprof_error::bad_magic:
38       return "Invalid instrumentation profile data (bad magic)";
39     case instrprof_error::bad_header:
40       return "Invalid instrumentation profile data (file header is corrupt)";
41     case instrprof_error::unsupported_version:
42       return "Unsupported instrumentation profile format version";
43     case instrprof_error::unsupported_hash_type:
44       return "Unsupported instrumentation profile hash type";
45     case instrprof_error::too_large:
46       return "Too much profile data";
47     case instrprof_error::truncated:
48       return "Truncated profile data";
49     case instrprof_error::malformed:
50       return "Malformed instrumentation profile data";
51     case instrprof_error::unknown_function:
52       return "No profile data available for function";
53     case instrprof_error::hash_mismatch:
54       return "Function control flow change detected (hash mismatch)";
55     case instrprof_error::count_mismatch:
56       return "Function basic block count change detected (counter mismatch)";
57     case instrprof_error::counter_overflow:
58       return "Counter overflow";
59     case instrprof_error::value_site_count_mismatch:
60       return "Function value site count change detected (counter mismatch)";
61     }
62     llvm_unreachable("A value of instrprof_error has no message.");
63   }
64 };
65 }
66 
67 static ManagedStatic<InstrProfErrorCategoryType> ErrorCategory;
68 
69 const std::error_category &llvm::instrprof_category() {
70   return *ErrorCategory;
71 }
72 
73 namespace llvm {
74 
75 std::string getPGOFuncName(StringRef RawFuncName,
76                            GlobalValue::LinkageTypes Linkage,
77                            StringRef FileName) {
78 
79   // Function names may be prefixed with a binary '1' to indicate
80   // that the backend should not modify the symbols due to any platform
81   // naming convention. Do not include that '1' in the PGO profile name.
82   if (RawFuncName[0] == '\1')
83     RawFuncName = RawFuncName.substr(1);
84 
85   std::string FuncName = RawFuncName;
86   if (llvm::GlobalValue::isLocalLinkage(Linkage)) {
87     // For local symbols, prepend the main file name to distinguish them.
88     // Do not include the full path in the file name since there's no guarantee
89     // that it will stay the same, e.g., if the files are checked out from
90     // version control in different locations.
91     if (FileName.empty())
92       FuncName = FuncName.insert(0, "<unknown>:");
93     else
94       FuncName = FuncName.insert(0, FileName.str() + ":");
95   }
96   return FuncName;
97 }
98 
99 std::string getPGOFuncName(const Function &F) {
100   return getPGOFuncName(F.getName(), F.getLinkage(), F.getParent()->getName());
101 }
102 
103 GlobalVariable *createPGOFuncNameVar(Module &M,
104                                      GlobalValue::LinkageTypes Linkage,
105                                      StringRef FuncName) {
106 
107   // We generally want to match the function's linkage, but available_externally
108   // and extern_weak both have the wrong semantics, and anything that doesn't
109   // need to link across compilation units doesn't need to be visible at all.
110   if (Linkage == GlobalValue::ExternalWeakLinkage)
111     Linkage = GlobalValue::LinkOnceAnyLinkage;
112   else if (Linkage == GlobalValue::AvailableExternallyLinkage)
113     Linkage = GlobalValue::LinkOnceODRLinkage;
114   else if (Linkage == GlobalValue::InternalLinkage ||
115            Linkage == GlobalValue::ExternalLinkage)
116     Linkage = GlobalValue::PrivateLinkage;
117 
118   auto *Value = ConstantDataArray::getString(M.getContext(), FuncName, false);
119   auto FuncNameVar =
120       new GlobalVariable(M, Value->getType(), true, Linkage, Value,
121                          Twine(getInstrProfNameVarPrefix()) + FuncName);
122 
123   // Hide the symbol so that we correctly get a copy for each executable.
124   if (!GlobalValue::isLocalLinkage(FuncNameVar->getLinkage()))
125     FuncNameVar->setVisibility(GlobalValue::HiddenVisibility);
126 
127   return FuncNameVar;
128 }
129 
130 GlobalVariable *createPGOFuncNameVar(Function &F, StringRef FuncName) {
131   return createPGOFuncNameVar(*F.getParent(), F.getLinkage(), FuncName);
132 }
133 
134 #define INSTR_PROF_COMMON_API_IMPL
135 #include "llvm/ProfileData/InstrProfData.inc"
136 
137 
138 /*!
139  * \brief ValueProfRecordClosure Interface implementation for  InstrProfRecord
140  *  class. These C wrappers are used as adaptors so that C++ code can be
141  *  invoked as callbacks.
142  */
143 uint32_t getNumValueKindsInstrProf(const void *Record) {
144   return reinterpret_cast<const InstrProfRecord *>(Record)->getNumValueKinds();
145 }
146 
147 uint32_t getNumValueSitesInstrProf(const void *Record, uint32_t VKind) {
148   return reinterpret_cast<const InstrProfRecord *>(Record)
149       ->getNumValueSites(VKind);
150 }
151 
152 uint32_t getNumValueDataInstrProf(const void *Record, uint32_t VKind) {
153   return reinterpret_cast<const InstrProfRecord *>(Record)
154       ->getNumValueData(VKind);
155 }
156 
157 uint32_t getNumValueDataForSiteInstrProf(const void *R, uint32_t VK,
158                                          uint32_t S) {
159   return reinterpret_cast<const InstrProfRecord *>(R)
160       ->getNumValueDataForSite(VK, S);
161 }
162 
163 void getValueForSiteInstrProf(const void *R, InstrProfValueData *Dst,
164                               uint32_t K, uint32_t S,
165                               uint64_t (*Mapper)(uint32_t, uint64_t)) {
166   return reinterpret_cast<const InstrProfRecord *>(R)
167       ->getValueForSite(Dst, K, S, Mapper);
168 }
169 
170 uint64_t stringToHash(uint32_t ValueKind, uint64_t Value) {
171   switch (ValueKind) {
172   case IPVK_IndirectCallTarget:
173     return IndexedInstrProf::ComputeHash(IndexedInstrProf::HashType,
174                                          (const char *)Value);
175     break;
176   default:
177     llvm_unreachable("value kind not handled !");
178   }
179   return Value;
180 }
181 
182 ValueProfData *allocValueProfDataInstrProf(size_t TotalSizeInBytes) {
183   return (ValueProfData *)(new (::operator new(TotalSizeInBytes))
184                                ValueProfData());
185 }
186 
187 static ValueProfRecordClosure InstrProfRecordClosure = {
188     0,
189     getNumValueKindsInstrProf,
190     getNumValueSitesInstrProf,
191     getNumValueDataInstrProf,
192     getNumValueDataForSiteInstrProf,
193     stringToHash,
194     getValueForSiteInstrProf,
195     allocValueProfDataInstrProf
196 };
197 
198 // Wrapper implementation using the closure mechanism.
199 uint32_t ValueProfData::getSize(const InstrProfRecord &Record) {
200   InstrProfRecordClosure.Record = &Record;
201   return getValueProfDataSize(&InstrProfRecordClosure);
202 }
203 
204 // Wrapper implementation using the closure mechanism.
205 std::unique_ptr<ValueProfData>
206 ValueProfData::serializeFrom(const InstrProfRecord &Record) {
207   InstrProfRecordClosure.Record = &Record;
208 
209   std::unique_ptr<ValueProfData> VPD(
210       serializeValueProfDataFrom(&InstrProfRecordClosure, nullptr));
211   return VPD;
212 }
213 
214 void ValueProfRecord::deserializeTo(InstrProfRecord &Record,
215                                     InstrProfRecord::ValueMapType *VMap) {
216   Record.reserveSites(Kind, NumValueSites);
217 
218   InstrProfValueData *ValueData = getValueProfRecordValueData(this);
219   for (uint64_t VSite = 0; VSite < NumValueSites; ++VSite) {
220     uint8_t ValueDataCount = this->SiteCountArray[VSite];
221     Record.addValueData(Kind, VSite, ValueData, ValueDataCount, VMap);
222     ValueData += ValueDataCount;
223   }
224 }
225 
226 // For writing/serializing,  Old is the host endianness, and  New is
227 // byte order intended on disk. For Reading/deserialization, Old
228 // is the on-disk source endianness, and New is the host endianness.
229 void ValueProfRecord::swapBytes(support::endianness Old,
230                                 support::endianness New) {
231   using namespace support;
232   if (Old == New)
233     return;
234 
235   if (getHostEndianness() != Old) {
236     sys::swapByteOrder<uint32_t>(NumValueSites);
237     sys::swapByteOrder<uint32_t>(Kind);
238   }
239   uint32_t ND = getValueProfRecordNumValueData(this);
240   InstrProfValueData *VD = getValueProfRecordValueData(this);
241 
242   // No need to swap byte array: SiteCountArrray.
243   for (uint32_t I = 0; I < ND; I++) {
244     sys::swapByteOrder<uint64_t>(VD[I].Value);
245     sys::swapByteOrder<uint64_t>(VD[I].Count);
246   }
247   if (getHostEndianness() == Old) {
248     sys::swapByteOrder<uint32_t>(NumValueSites);
249     sys::swapByteOrder<uint32_t>(Kind);
250   }
251 }
252 
253 void ValueProfData::deserializeTo(InstrProfRecord &Record,
254                                   InstrProfRecord::ValueMapType *VMap) {
255   if (NumValueKinds == 0)
256     return;
257 
258   ValueProfRecord *VR = getFirstValueProfRecord(this);
259   for (uint32_t K = 0; K < NumValueKinds; K++) {
260     VR->deserializeTo(Record, VMap);
261     VR = getValueProfRecordNext(VR);
262   }
263 }
264 
265 template <class T>
266 static T swapToHostOrder(const unsigned char *&D, support::endianness Orig) {
267   using namespace support;
268   if (Orig == little)
269     return endian::readNext<T, little, unaligned>(D);
270   else
271     return endian::readNext<T, big, unaligned>(D);
272 }
273 
274 static std::unique_ptr<ValueProfData> allocValueProfData(uint32_t TotalSize) {
275   return std::unique_ptr<ValueProfData>(new (::operator new(TotalSize))
276                                             ValueProfData());
277 }
278 
279 instrprof_error ValueProfData::checkIntegrity() {
280   if (NumValueKinds > IPVK_Last + 1)
281     return instrprof_error::malformed;
282   // Total size needs to be mulltiple of quadword size.
283   if (TotalSize % sizeof(uint64_t))
284     return instrprof_error::malformed;
285 
286   ValueProfRecord *VR = getFirstValueProfRecord(this);
287   for (uint32_t K = 0; K < this->NumValueKinds; K++) {
288     if (VR->Kind > IPVK_Last)
289       return instrprof_error::malformed;
290     VR = getValueProfRecordNext(VR);
291     if ((char *)VR - (char *)this > (ptrdiff_t)TotalSize)
292       return instrprof_error::malformed;
293   }
294   return instrprof_error::success;
295 }
296 
297 ErrorOr<std::unique_ptr<ValueProfData>>
298 ValueProfData::getValueProfData(const unsigned char *D,
299                                 const unsigned char *const BufferEnd,
300                                 support::endianness Endianness) {
301   using namespace support;
302   if (D + sizeof(ValueProfData) > BufferEnd)
303     return instrprof_error::truncated;
304 
305   const unsigned char *Header = D;
306   uint32_t TotalSize = swapToHostOrder<uint32_t>(Header, Endianness);
307   if (D + TotalSize > BufferEnd)
308     return instrprof_error::too_large;
309 
310   std::unique_ptr<ValueProfData> VPD = allocValueProfData(TotalSize);
311   memcpy(VPD.get(), D, TotalSize);
312   // Byte swap.
313   VPD->swapBytesToHost(Endianness);
314 
315   instrprof_error EC = VPD->checkIntegrity();
316   if (EC != instrprof_error::success)
317     return EC;
318 
319   return std::move(VPD);
320 }
321 
322 void ValueProfData::swapBytesToHost(support::endianness Endianness) {
323   using namespace support;
324   if (Endianness == getHostEndianness())
325     return;
326 
327   sys::swapByteOrder<uint32_t>(TotalSize);
328   sys::swapByteOrder<uint32_t>(NumValueKinds);
329 
330   ValueProfRecord *VR = getFirstValueProfRecord(this);
331   for (uint32_t K = 0; K < NumValueKinds; K++) {
332     VR->swapBytes(Endianness, getHostEndianness());
333     VR = getValueProfRecordNext(VR);
334   }
335 }
336 
337 void ValueProfData::swapBytesFromHost(support::endianness Endianness) {
338   using namespace support;
339   if (Endianness == getHostEndianness())
340     return;
341 
342   ValueProfRecord *VR = getFirstValueProfRecord(this);
343   for (uint32_t K = 0; K < NumValueKinds; K++) {
344     ValueProfRecord *NVR = getValueProfRecordNext(VR);
345     VR->swapBytes(getHostEndianness(), Endianness);
346     VR = NVR;
347   }
348   sys::swapByteOrder<uint32_t>(TotalSize);
349   sys::swapByteOrder<uint32_t>(NumValueKinds);
350 }
351 
352 }
353