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                            uint64_t Version LLVM_ATTRIBUTE_UNUSED) {
79 
80   // Function names may be prefixed with a binary '1' to indicate
81   // that the backend should not modify the symbols due to any platform
82   // naming convention. Do not include that '1' in the PGO profile name.
83   if (RawFuncName[0] == '\1')
84     RawFuncName = RawFuncName.substr(1);
85 
86   std::string FuncName = RawFuncName;
87   if (llvm::GlobalValue::isLocalLinkage(Linkage)) {
88     // For local symbols, prepend the main file name to distinguish them.
89     // Do not include the full path in the file name since there's no guarantee
90     // that it will stay the same, e.g., if the files are checked out from
91     // version control in different locations.
92     if (FileName.empty())
93       FuncName = FuncName.insert(0, "<unknown>:");
94     else
95       FuncName = FuncName.insert(0, FileName.str() + ":");
96   }
97   return FuncName;
98 }
99 
100 std::string getPGOFuncName(const Function &F, uint64_t Version) {
101   return getPGOFuncName(F.getName(), F.getLinkage(), F.getParent()->getName(),
102                         Version);
103 }
104 
105 GlobalVariable *createPGOFuncNameVar(Module &M,
106                                      GlobalValue::LinkageTypes Linkage,
107                                      StringRef FuncName) {
108 
109   // We generally want to match the function's linkage, but available_externally
110   // and extern_weak both have the wrong semantics, and anything that doesn't
111   // need to link across compilation units doesn't need to be visible at all.
112   if (Linkage == GlobalValue::ExternalWeakLinkage)
113     Linkage = GlobalValue::LinkOnceAnyLinkage;
114   else if (Linkage == GlobalValue::AvailableExternallyLinkage)
115     Linkage = GlobalValue::LinkOnceODRLinkage;
116   else if (Linkage == GlobalValue::InternalLinkage ||
117            Linkage == GlobalValue::ExternalLinkage)
118     Linkage = GlobalValue::PrivateLinkage;
119 
120   auto *Value = ConstantDataArray::getString(M.getContext(), FuncName, false);
121   auto FuncNameVar =
122       new GlobalVariable(M, Value->getType(), true, Linkage, Value,
123                          Twine(getInstrProfNameVarPrefix()) + FuncName);
124 
125   // Hide the symbol so that we correctly get a copy for each executable.
126   if (!GlobalValue::isLocalLinkage(FuncNameVar->getLinkage()))
127     FuncNameVar->setVisibility(GlobalValue::HiddenVisibility);
128 
129   return FuncNameVar;
130 }
131 
132 GlobalVariable *createPGOFuncNameVar(Function &F, StringRef FuncName) {
133   return createPGOFuncNameVar(*F.getParent(), F.getLinkage(), FuncName);
134 }
135 
136 #define INSTR_PROF_COMMON_API_IMPL
137 #include "llvm/ProfileData/InstrProfData.inc"
138 
139 
140 /*!
141  * \brief ValueProfRecordClosure Interface implementation for  InstrProfRecord
142  *  class. These C wrappers are used as adaptors so that C++ code can be
143  *  invoked as callbacks.
144  */
145 uint32_t getNumValueKindsInstrProf(const void *Record) {
146   return reinterpret_cast<const InstrProfRecord *>(Record)->getNumValueKinds();
147 }
148 
149 uint32_t getNumValueSitesInstrProf(const void *Record, uint32_t VKind) {
150   return reinterpret_cast<const InstrProfRecord *>(Record)
151       ->getNumValueSites(VKind);
152 }
153 
154 uint32_t getNumValueDataInstrProf(const void *Record, uint32_t VKind) {
155   return reinterpret_cast<const InstrProfRecord *>(Record)
156       ->getNumValueData(VKind);
157 }
158 
159 uint32_t getNumValueDataForSiteInstrProf(const void *R, uint32_t VK,
160                                          uint32_t S) {
161   return reinterpret_cast<const InstrProfRecord *>(R)
162       ->getNumValueDataForSite(VK, S);
163 }
164 
165 void getValueForSiteInstrProf(const void *R, InstrProfValueData *Dst,
166                               uint32_t K, uint32_t S,
167                               uint64_t (*Mapper)(uint32_t, uint64_t)) {
168   return reinterpret_cast<const InstrProfRecord *>(R)
169       ->getValueForSite(Dst, K, S, Mapper);
170 }
171 
172 uint64_t stringToHash(uint32_t ValueKind, uint64_t Value) {
173   switch (ValueKind) {
174   case IPVK_IndirectCallTarget:
175     return IndexedInstrProf::ComputeHash(IndexedInstrProf::HashType,
176                                          (const char *)Value);
177     break;
178   default:
179     llvm_unreachable("value kind not handled !");
180   }
181   return Value;
182 }
183 
184 ValueProfData *allocValueProfDataInstrProf(size_t TotalSizeInBytes) {
185   return (ValueProfData *)(new (::operator new(TotalSizeInBytes))
186                                ValueProfData());
187 }
188 
189 static ValueProfRecordClosure InstrProfRecordClosure = {
190     0,
191     getNumValueKindsInstrProf,
192     getNumValueSitesInstrProf,
193     getNumValueDataInstrProf,
194     getNumValueDataForSiteInstrProf,
195     stringToHash,
196     getValueForSiteInstrProf,
197     allocValueProfDataInstrProf
198 };
199 
200 // Wrapper implementation using the closure mechanism.
201 uint32_t ValueProfData::getSize(const InstrProfRecord &Record) {
202   InstrProfRecordClosure.Record = &Record;
203   return getValueProfDataSize(&InstrProfRecordClosure);
204 }
205 
206 // Wrapper implementation using the closure mechanism.
207 std::unique_ptr<ValueProfData>
208 ValueProfData::serializeFrom(const InstrProfRecord &Record) {
209   InstrProfRecordClosure.Record = &Record;
210 
211   std::unique_ptr<ValueProfData> VPD(
212       serializeValueProfDataFrom(&InstrProfRecordClosure, nullptr));
213   return VPD;
214 }
215 
216 void ValueProfRecord::deserializeTo(InstrProfRecord &Record,
217                                     InstrProfRecord::ValueMapType *VMap) {
218   Record.reserveSites(Kind, NumValueSites);
219 
220   InstrProfValueData *ValueData = getValueProfRecordValueData(this);
221   for (uint64_t VSite = 0; VSite < NumValueSites; ++VSite) {
222     uint8_t ValueDataCount = this->SiteCountArray[VSite];
223     Record.addValueData(Kind, VSite, ValueData, ValueDataCount, VMap);
224     ValueData += ValueDataCount;
225   }
226 }
227 
228 // For writing/serializing,  Old is the host endianness, and  New is
229 // byte order intended on disk. For Reading/deserialization, Old
230 // is the on-disk source endianness, and New is the host endianness.
231 void ValueProfRecord::swapBytes(support::endianness Old,
232                                 support::endianness New) {
233   using namespace support;
234   if (Old == New)
235     return;
236 
237   if (getHostEndianness() != Old) {
238     sys::swapByteOrder<uint32_t>(NumValueSites);
239     sys::swapByteOrder<uint32_t>(Kind);
240   }
241   uint32_t ND = getValueProfRecordNumValueData(this);
242   InstrProfValueData *VD = getValueProfRecordValueData(this);
243 
244   // No need to swap byte array: SiteCountArrray.
245   for (uint32_t I = 0; I < ND; I++) {
246     sys::swapByteOrder<uint64_t>(VD[I].Value);
247     sys::swapByteOrder<uint64_t>(VD[I].Count);
248   }
249   if (getHostEndianness() == Old) {
250     sys::swapByteOrder<uint32_t>(NumValueSites);
251     sys::swapByteOrder<uint32_t>(Kind);
252   }
253 }
254 
255 void ValueProfData::deserializeTo(InstrProfRecord &Record,
256                                   InstrProfRecord::ValueMapType *VMap) {
257   if (NumValueKinds == 0)
258     return;
259 
260   ValueProfRecord *VR = getFirstValueProfRecord(this);
261   for (uint32_t K = 0; K < NumValueKinds; K++) {
262     VR->deserializeTo(Record, VMap);
263     VR = getValueProfRecordNext(VR);
264   }
265 }
266 
267 template <class T>
268 static T swapToHostOrder(const unsigned char *&D, support::endianness Orig) {
269   using namespace support;
270   if (Orig == little)
271     return endian::readNext<T, little, unaligned>(D);
272   else
273     return endian::readNext<T, big, unaligned>(D);
274 }
275 
276 static std::unique_ptr<ValueProfData> allocValueProfData(uint32_t TotalSize) {
277   return std::unique_ptr<ValueProfData>(new (::operator new(TotalSize))
278                                             ValueProfData());
279 }
280 
281 instrprof_error ValueProfData::checkIntegrity() {
282   if (NumValueKinds > IPVK_Last + 1)
283     return instrprof_error::malformed;
284   // Total size needs to be mulltiple of quadword size.
285   if (TotalSize % sizeof(uint64_t))
286     return instrprof_error::malformed;
287 
288   ValueProfRecord *VR = getFirstValueProfRecord(this);
289   for (uint32_t K = 0; K < this->NumValueKinds; K++) {
290     if (VR->Kind > IPVK_Last)
291       return instrprof_error::malformed;
292     VR = getValueProfRecordNext(VR);
293     if ((char *)VR - (char *)this > (ptrdiff_t)TotalSize)
294       return instrprof_error::malformed;
295   }
296   return instrprof_error::success;
297 }
298 
299 ErrorOr<std::unique_ptr<ValueProfData>>
300 ValueProfData::getValueProfData(const unsigned char *D,
301                                 const unsigned char *const BufferEnd,
302                                 support::endianness Endianness) {
303   using namespace support;
304   if (D + sizeof(ValueProfData) > BufferEnd)
305     return instrprof_error::truncated;
306 
307   const unsigned char *Header = D;
308   uint32_t TotalSize = swapToHostOrder<uint32_t>(Header, Endianness);
309   if (D + TotalSize > BufferEnd)
310     return instrprof_error::too_large;
311 
312   std::unique_ptr<ValueProfData> VPD = allocValueProfData(TotalSize);
313   memcpy(VPD.get(), D, TotalSize);
314   // Byte swap.
315   VPD->swapBytesToHost(Endianness);
316 
317   instrprof_error EC = VPD->checkIntegrity();
318   if (EC != instrprof_error::success)
319     return EC;
320 
321   return std::move(VPD);
322 }
323 
324 void ValueProfData::swapBytesToHost(support::endianness Endianness) {
325   using namespace support;
326   if (Endianness == getHostEndianness())
327     return;
328 
329   sys::swapByteOrder<uint32_t>(TotalSize);
330   sys::swapByteOrder<uint32_t>(NumValueKinds);
331 
332   ValueProfRecord *VR = getFirstValueProfRecord(this);
333   for (uint32_t K = 0; K < NumValueKinds; K++) {
334     VR->swapBytes(Endianness, getHostEndianness());
335     VR = getValueProfRecordNext(VR);
336   }
337 }
338 
339 void ValueProfData::swapBytesFromHost(support::endianness Endianness) {
340   using namespace support;
341   if (Endianness == getHostEndianness())
342     return;
343 
344   ValueProfRecord *VR = getFirstValueProfRecord(this);
345   for (uint32_t K = 0; K < NumValueKinds; K++) {
346     ValueProfRecord *NVR = getValueProfRecordNext(VR);
347     VR->swapBytes(getHostEndianness(), Endianness);
348     VR = NVR;
349   }
350   sys::swapByteOrder<uint32_t>(TotalSize);
351   sys::swapByteOrder<uint32_t>(NumValueKinds);
352 }
353 
354 }
355