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::bad_magic:
36       return "Invalid profile data (bad magic)";
37     case instrprof_error::bad_header:
38       return "Invalid profile data (file header is corrupt)";
39     case instrprof_error::unsupported_version:
40       return "Unsupported profiling format version";
41     case instrprof_error::unsupported_hash_type:
42       return "Unsupported profiling hash";
43     case instrprof_error::too_large:
44       return "Too much profile data";
45     case instrprof_error::truncated:
46       return "Truncated profile data";
47     case instrprof_error::malformed:
48       return "Malformed profile data";
49     case instrprof_error::unknown_function:
50       return "No profile data available for function";
51     case instrprof_error::hash_mismatch:
52       return "Function hash mismatch";
53     case instrprof_error::count_mismatch:
54       return "Function count mismatch";
55     case instrprof_error::counter_overflow:
56       return "Counter overflow";
57     case instrprof_error::value_site_count_mismatch:
58       return "Function's value site counts mismatch";
59     }
60     llvm_unreachable("A value of instrprof_error has no message.");
61   }
62 };
63 }
64 
65 static ManagedStatic<InstrProfErrorCategoryType> ErrorCategory;
66 
67 const std::error_category &llvm::instrprof_category() {
68   return *ErrorCategory;
69 }
70 
71 namespace llvm {
72 
73 std::string getPGOFuncName(StringRef RawFuncName,
74                            GlobalValue::LinkageTypes Linkage,
75                            StringRef FileName) {
76 
77   // Function names may be prefixed with a binary '1' to indicate
78   // that the backend should not modify the symbols due to any platform
79   // naming convention. Do not include that '1' in the PGO profile name.
80   if (RawFuncName[0] == '\1')
81     RawFuncName = RawFuncName.substr(1);
82 
83   std::string FuncName = RawFuncName;
84   if (llvm::GlobalValue::isLocalLinkage(Linkage)) {
85     // For local symbols, prepend the main file name to distinguish them.
86     // Do not include the full path in the file name since there's no guarantee
87     // that it will stay the same, e.g., if the files are checked out from
88     // version control in different locations.
89     if (FileName.empty())
90       FuncName = FuncName.insert(0, "<unknown>:");
91     else
92       FuncName = FuncName.insert(0, FileName.str() + ":");
93   }
94   return FuncName;
95 }
96 
97 std::string getPGOFuncName(const Function &F) {
98   return getPGOFuncName(F.getName(), F.getLinkage(), F.getParent()->getName());
99 }
100 
101 GlobalVariable *createPGOFuncNameVar(Module &M,
102                                      GlobalValue::LinkageTypes Linkage,
103                                      StringRef FuncName) {
104 
105   // We generally want to match the function's linkage, but available_externally
106   // and extern_weak both have the wrong semantics, and anything that doesn't
107   // need to link across compilation units doesn't need to be visible at all.
108   if (Linkage == GlobalValue::ExternalWeakLinkage)
109     Linkage = GlobalValue::LinkOnceAnyLinkage;
110   else if (Linkage == GlobalValue::AvailableExternallyLinkage)
111     Linkage = GlobalValue::LinkOnceODRLinkage;
112   else if (Linkage == GlobalValue::InternalLinkage ||
113            Linkage == GlobalValue::ExternalLinkage)
114     Linkage = GlobalValue::PrivateLinkage;
115 
116   auto *Value = ConstantDataArray::getString(M.getContext(), FuncName, false);
117   auto FuncNameVar =
118       new GlobalVariable(M, Value->getType(), true, Linkage, Value,
119                          Twine(getInstrProfNameVarPrefix()) + FuncName);
120 
121   // Hide the symbol so that we correctly get a copy for each executable.
122   if (!GlobalValue::isLocalLinkage(FuncNameVar->getLinkage()))
123     FuncNameVar->setVisibility(GlobalValue::HiddenVisibility);
124 
125   return FuncNameVar;
126 }
127 
128 GlobalVariable *createPGOFuncNameVar(Function &F, StringRef FuncName) {
129   return createPGOFuncNameVar(*F.getParent(), F.getLinkage(), FuncName);
130 }
131 
132 namespace IndexedInstrProf {
133 
134 uint32_t ValueProfRecord::getHeaderSize(uint32_t NumValueSites) {
135   uint32_t Size = offsetof(ValueProfRecord, SiteCountArray) +
136                   sizeof(uint8_t) * NumValueSites;
137   // Round the size to multiple of 8 bytes.
138   Size = (Size + 7) & ~7;
139   return Size;
140 }
141 
142 uint32_t ValueProfRecord::getSize(uint32_t NumValueSites,
143                                   uint32_t NumValueData) {
144   return getHeaderSize(NumValueSites) +
145          sizeof(InstrProfValueData) * NumValueData;
146 }
147 
148 void ValueProfRecord::deserializeTo(InstrProfRecord &Record,
149                                     InstrProfRecord::ValueMapType *VMap) {
150   Record.reserveSites(Kind, NumValueSites);
151 
152   InstrProfValueData *ValueData = this->getValueData();
153   for (uint64_t VSite = 0; VSite < NumValueSites; ++VSite) {
154     uint8_t ValueDataCount = this->SiteCountArray[VSite];
155     Record.addValueData(Kind, VSite, ValueData, ValueDataCount, VMap);
156     ValueData += ValueDataCount;
157   }
158 }
159 
160 void ValueProfRecord::serializeFrom(const InstrProfRecord &Record,
161                                     uint32_t ValueKind,
162                                     uint32_t NumValueSites) {
163   Kind = ValueKind;
164   this->NumValueSites = NumValueSites;
165   InstrProfValueData *DstVD = getValueData();
166   for (uint32_t S = 0; S < NumValueSites; S++) {
167     uint32_t ND = Record.getNumValueDataForSite(ValueKind, S);
168     SiteCountArray[S] = ND;
169     std::unique_ptr<InstrProfValueData[]> SrcVD =
170         Record.getValueForSite(ValueKind, S);
171     for (uint32_t I = 0; I < ND; I++) {
172       DstVD[I] = SrcVD[I];
173       switch (ValueKind) {
174       case IPVK_IndirectCallTarget:
175         DstVD[I].Value = ComputeHash(HashType, (const char *)DstVD[I].Value);
176         break;
177       default:
178         llvm_unreachable("value kind not handled !");
179       }
180     }
181     DstVD += ND;
182   }
183 }
184 
185 template <class T> static T swapToHostOrder(T v, support::endianness Orig) {
186   if (Orig == getHostEndianness())
187     return v;
188   sys::swapByteOrder<T>(v);
189   return v;
190 }
191 
192 // For writing/serializing,  Old is the host endianness, and  New is
193 // byte order intended on disk. For Reading/deserialization, Old
194 // is the on-disk source endianness, and New is the host endianness.
195 void ValueProfRecord::swapBytes(support::endianness Old,
196                                 support::endianness New) {
197   using namespace support;
198   if (Old == New)
199     return;
200 
201   if (getHostEndianness() != Old) {
202     sys::swapByteOrder<uint32_t>(NumValueSites);
203     sys::swapByteOrder<uint32_t>(Kind);
204   }
205   uint32_t ND = getNumValueData();
206   InstrProfValueData *VD = getValueData();
207 
208   // No need to swap byte array: SiteCountArrray.
209   for (uint32_t I = 0; I < ND; I++) {
210     sys::swapByteOrder<uint64_t>(VD[I].Value);
211     sys::swapByteOrder<uint64_t>(VD[I].Count);
212   }
213   if (getHostEndianness() == Old) {
214     sys::swapByteOrder<uint32_t>(NumValueSites);
215     sys::swapByteOrder<uint32_t>(Kind);
216   }
217 }
218 
219 uint32_t ValueProfData::getSize(const InstrProfRecord &Record) {
220   uint32_t TotalSize = sizeof(ValueProfData);
221   uint32_t NumValueKinds = Record.getNumValueKinds();
222   if (NumValueKinds == 0)
223     return TotalSize;
224 
225   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; Kind++) {
226     uint32_t NumValueSites = Record.getNumValueSites(Kind);
227     if (!NumValueSites)
228       continue;
229     TotalSize +=
230         ValueProfRecord::getSize(NumValueSites, Record.getNumValueData(Kind));
231   }
232   return TotalSize;
233 }
234 
235 void ValueProfData::deserializeTo(InstrProfRecord &Record,
236                                   InstrProfRecord::ValueMapType *VMap) {
237   if (NumValueKinds == 0)
238     return;
239 
240   ValueProfRecord *VR = getFirstValueProfRecord();
241   for (uint32_t K = 0; K < NumValueKinds; K++) {
242     VR->deserializeTo(Record, VMap);
243     VR = VR->getNext();
244   }
245 }
246 
247 static std::unique_ptr<ValueProfData> AllocValueProfData(uint32_t TotalSize) {
248   return std::unique_ptr<ValueProfData>(new (::operator new(TotalSize))
249                                             ValueProfData());
250 }
251 
252 std::unique_ptr<ValueProfData>
253 ValueProfData::serializeFrom(const InstrProfRecord &Record) {
254   uint32_t TotalSize = getSize(Record);
255 
256   std::unique_ptr<ValueProfData> VPD = AllocValueProfData(TotalSize);
257 
258   VPD->TotalSize = TotalSize;
259   VPD->NumValueKinds = Record.getNumValueKinds();
260   ValueProfRecord *VR = VPD->getFirstValueProfRecord();
261   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; Kind++) {
262     uint32_t NumValueSites = Record.getNumValueSites(Kind);
263     if (!NumValueSites)
264       continue;
265     VR->serializeFrom(Record, Kind, NumValueSites);
266     VR = VR->getNext();
267   }
268   return VPD;
269 }
270 
271 ErrorOr<std::unique_ptr<ValueProfData>>
272 ValueProfData::getValueProfData(const unsigned char *D,
273                                 const unsigned char *const BufferEnd,
274                                 support::endianness Endianness) {
275   using namespace support;
276   if (D + sizeof(ValueProfData) > BufferEnd)
277     return instrprof_error::truncated;
278 
279   uint32_t TotalSize = swapToHostOrder<uint32_t>(
280       reinterpret_cast<const uint32_t *>(D)[0], Endianness);
281   uint32_t NumValueKinds = swapToHostOrder<uint32_t>(
282       reinterpret_cast<const uint32_t *>(D)[1], Endianness);
283 
284   if (D + TotalSize > BufferEnd)
285     return instrprof_error::too_large;
286   if (NumValueKinds > IPVK_Last + 1)
287     return instrprof_error::malformed;
288   // Total size needs to be mulltiple of quadword size.
289   if (TotalSize % sizeof(uint64_t))
290     return instrprof_error::malformed;
291 
292   std::unique_ptr<ValueProfData> VPD = AllocValueProfData(TotalSize);
293 
294   memcpy(VPD.get(), D, TotalSize);
295   // Byte swap.
296   VPD->swapBytesToHost(Endianness);
297 
298   // Data integrety check:
299   ValueProfRecord *VR = VPD->getFirstValueProfRecord();
300   for (uint32_t K = 0; K < VPD->NumValueKinds; K++) {
301     if (VR->Kind > IPVK_Last)
302       return instrprof_error::malformed;
303     VR = VR->getNext();
304     if ((char *)VR - (char *)VPD.get() > (ptrdiff_t)TotalSize)
305       return instrprof_error::malformed;
306   }
307 
308   D += TotalSize;
309   return std::move(VPD);
310 }
311 
312 void ValueProfData::swapBytesToHost(support::endianness Endianness) {
313   using namespace support;
314   if (Endianness == getHostEndianness())
315     return;
316 
317   sys::swapByteOrder<uint32_t>(TotalSize);
318   sys::swapByteOrder<uint32_t>(NumValueKinds);
319 
320   ValueProfRecord *VR = getFirstValueProfRecord();
321   for (uint32_t K = 0; K < NumValueKinds; K++) {
322     VR->swapBytes(Endianness, getHostEndianness());
323     VR = VR->getNext();
324   }
325 }
326 
327 void ValueProfData::swapBytesFromHost(support::endianness Endianness) {
328   using namespace support;
329   if (Endianness == getHostEndianness())
330     return;
331 
332   ValueProfRecord *VR = getFirstValueProfRecord();
333   for (uint32_t K = 0; K < NumValueKinds; K++) {
334     ValueProfRecord *NVR = VR->getNext();
335     VR->swapBytes(getHostEndianness(), Endianness);
336     VR = NVR;
337   }
338   sys::swapByteOrder<uint32_t>(TotalSize);
339   sys::swapByteOrder<uint32_t>(NumValueKinds);
340 }
341 
342 ValueProfRecord *ValueProfData::getFirstValueProfRecord() {
343   return reinterpret_cast<ValueProfRecord *>((char *)this +
344                                              sizeof(ValueProfData));
345 }
346 
347 uint32_t ValueProfRecord::getNumValueData() const {
348   uint32_t NumValueData = 0;
349   for (uint32_t I = 0; I < NumValueSites; I++)
350     NumValueData += SiteCountArray[I];
351   return NumValueData;
352 }
353 
354 ValueProfRecord *ValueProfRecord::getNext() {
355   return reinterpret_cast<ValueProfRecord *>((char *)this + getSize());
356 }
357 
358 InstrProfValueData *ValueProfRecord::getValueData() {
359   return reinterpret_cast<InstrProfValueData *>((char *)this +
360                                                 getHeaderSize(NumValueSites));
361 }
362 
363 } // End of IndexedInstrProf namespace.
364 }
365