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 void ValueProfRecord::deserializeTo(InstrProfRecord &Record,
135                                     InstrProfRecord::ValueMapType *VMap) {
136   Record.reserveSites(Kind, NumValueSites);
137 
138   InstrProfValueData *ValueData = this->getValueData();
139   for (uint64_t VSite = 0; VSite < NumValueSites; ++VSite) {
140     uint8_t ValueDataCount = this->SiteCountArray[VSite];
141     Record.addValueData(Kind, VSite, ValueData, ValueDataCount, VMap);
142     ValueData += ValueDataCount;
143   }
144 }
145 
146 void ValueProfRecord::serializeFrom(const InstrProfRecord &Record,
147                                     uint32_t ValueKind,
148                                     uint32_t NumValueSites) {
149   Kind = ValueKind;
150   this->NumValueSites = NumValueSites;
151   InstrProfValueData *DstVD = getValueData();
152   for (uint32_t S = 0; S < NumValueSites; S++) {
153     uint32_t ND = Record.getNumValueDataForSite(ValueKind, S);
154     SiteCountArray[S] = ND;
155     Record.getValueForSite(DstVD, ValueKind, S);
156     for (uint32_t I = 0; I < ND; I++) {
157       switch (ValueKind) {
158       case IPVK_IndirectCallTarget:
159         DstVD[I].Value = IndexedInstrProf::ComputeHash(
160             IndexedInstrProf::HashType, (const char *)DstVD[I].Value);
161         break;
162       default:
163         llvm_unreachable("value kind not handled !");
164       }
165     }
166     DstVD += ND;
167   }
168 }
169 
170 template <class T>
171 static T swapToHostOrder(const unsigned char *&D, support::endianness Orig) {
172   using namespace support;
173   if (Orig == little)
174     return endian::readNext<T, little, unaligned>(D);
175   else
176     return endian::readNext<T, big, unaligned>(D);
177 }
178 
179 // For writing/serializing,  Old is the host endianness, and  New is
180 // byte order intended on disk. For Reading/deserialization, Old
181 // is the on-disk source endianness, and New is the host endianness.
182 void ValueProfRecord::swapBytes(support::endianness Old,
183                                 support::endianness New) {
184   using namespace support;
185   if (Old == New)
186     return;
187 
188   if (getHostEndianness() != Old) {
189     sys::swapByteOrder<uint32_t>(NumValueSites);
190     sys::swapByteOrder<uint32_t>(Kind);
191   }
192   uint32_t ND = getNumValueData();
193   InstrProfValueData *VD = getValueData();
194 
195   // No need to swap byte array: SiteCountArrray.
196   for (uint32_t I = 0; I < ND; I++) {
197     sys::swapByteOrder<uint64_t>(VD[I].Value);
198     sys::swapByteOrder<uint64_t>(VD[I].Count);
199   }
200   if (getHostEndianness() == Old) {
201     sys::swapByteOrder<uint32_t>(NumValueSites);
202     sys::swapByteOrder<uint32_t>(Kind);
203   }
204 }
205 
206 uint32_t ValueProfData::getSize(const InstrProfRecord &Record) {
207   uint32_t TotalSize = sizeof(ValueProfData);
208   uint32_t NumValueKinds = Record.getNumValueKinds();
209   if (NumValueKinds == 0)
210     return TotalSize;
211 
212   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; Kind++) {
213     uint32_t NumValueSites = Record.getNumValueSites(Kind);
214     if (!NumValueSites)
215       continue;
216     TotalSize +=
217         getValueProfRecordSize(NumValueSites, Record.getNumValueData(Kind));
218   }
219   return TotalSize;
220 }
221 
222 void ValueProfData::deserializeTo(InstrProfRecord &Record,
223                                   InstrProfRecord::ValueMapType *VMap) {
224   if (NumValueKinds == 0)
225     return;
226 
227   ValueProfRecord *VR = getFirstValueProfRecord();
228   for (uint32_t K = 0; K < NumValueKinds; K++) {
229     VR->deserializeTo(Record, VMap);
230     VR = VR->getNext();
231   }
232 }
233 
234 static std::unique_ptr<ValueProfData> AllocValueProfData(uint32_t TotalSize) {
235   return std::unique_ptr<ValueProfData>(new (::operator new(TotalSize))
236                                             ValueProfData());
237 }
238 
239 std::unique_ptr<ValueProfData>
240 ValueProfData::serializeFrom(const InstrProfRecord &Record) {
241   uint32_t TotalSize = getSize(Record);
242 
243   std::unique_ptr<ValueProfData> VPD = AllocValueProfData(TotalSize);
244 
245   VPD->TotalSize = TotalSize;
246   VPD->NumValueKinds = Record.getNumValueKinds();
247   ValueProfRecord *VR = VPD->getFirstValueProfRecord();
248   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; Kind++) {
249     uint32_t NumValueSites = Record.getNumValueSites(Kind);
250     if (!NumValueSites)
251       continue;
252     VR->serializeFrom(Record, Kind, NumValueSites);
253     VR = VR->getNext();
254   }
255   return VPD;
256 }
257 
258 ErrorOr<std::unique_ptr<ValueProfData>>
259 ValueProfData::getValueProfData(const unsigned char *D,
260                                 const unsigned char *const BufferEnd,
261                                 support::endianness Endianness) {
262   using namespace support;
263   if (D + sizeof(ValueProfData) > BufferEnd)
264     return instrprof_error::truncated;
265 
266   const unsigned char *Header = D;
267   uint32_t TotalSize = swapToHostOrder<uint32_t>(Header, Endianness);
268   uint32_t NumValueKinds = swapToHostOrder<uint32_t>(Header, Endianness);
269 
270   if (D + TotalSize > BufferEnd)
271     return instrprof_error::too_large;
272   if (NumValueKinds > IPVK_Last + 1)
273     return instrprof_error::malformed;
274   // Total size needs to be mulltiple of quadword size.
275   if (TotalSize % sizeof(uint64_t))
276     return instrprof_error::malformed;
277 
278   std::unique_ptr<ValueProfData> VPD = AllocValueProfData(TotalSize);
279 
280   memcpy(VPD.get(), D, TotalSize);
281   // Byte swap.
282   VPD->swapBytesToHost(Endianness);
283 
284   // Data integrety check:
285   ValueProfRecord *VR = VPD->getFirstValueProfRecord();
286   for (uint32_t K = 0; K < VPD->NumValueKinds; K++) {
287     if (VR->Kind > IPVK_Last)
288       return instrprof_error::malformed;
289     VR = VR->getNext();
290     if ((char *)VR - (char *)VPD.get() > (ptrdiff_t)TotalSize)
291       return instrprof_error::malformed;
292   }
293 
294   return std::move(VPD);
295 }
296 
297 void ValueProfData::swapBytesToHost(support::endianness Endianness) {
298   using namespace support;
299   if (Endianness == getHostEndianness())
300     return;
301 
302   sys::swapByteOrder<uint32_t>(TotalSize);
303   sys::swapByteOrder<uint32_t>(NumValueKinds);
304 
305   ValueProfRecord *VR = getFirstValueProfRecord();
306   for (uint32_t K = 0; K < NumValueKinds; K++) {
307     VR->swapBytes(Endianness, getHostEndianness());
308     VR = VR->getNext();
309   }
310 }
311 
312 void ValueProfData::swapBytesFromHost(support::endianness Endianness) {
313   using namespace support;
314   if (Endianness == getHostEndianness())
315     return;
316 
317   ValueProfRecord *VR = getFirstValueProfRecord();
318   for (uint32_t K = 0; K < NumValueKinds; K++) {
319     ValueProfRecord *NVR = VR->getNext();
320     VR->swapBytes(getHostEndianness(), Endianness);
321     VR = NVR;
322   }
323   sys::swapByteOrder<uint32_t>(TotalSize);
324   sys::swapByteOrder<uint32_t>(NumValueKinds);
325 }
326 
327 ValueProfRecord *ValueProfData::getFirstValueProfRecord() {
328   return reinterpret_cast<ValueProfRecord *>((char *)this +
329                                              sizeof(ValueProfData));
330 }
331 
332 uint32_t ValueProfRecord::getNumValueData() const {
333   uint32_t NumValueData = 0;
334   for (uint32_t I = 0; I < NumValueSites; I++)
335     NumValueData += SiteCountArray[I];
336   return NumValueData;
337 }
338 
339 ValueProfRecord *ValueProfRecord::getNext() {
340   return reinterpret_cast<ValueProfRecord *>((char *)this + getSize());
341 }
342 
343 InstrProfValueData *ValueProfRecord::getValueData() {
344   return reinterpret_cast<InstrProfValueData *>(
345       (char *)this + getValueProfRecordHeaderSize(NumValueSites));
346 }
347 }
348