1 //===- SampleProfWriter.cpp - Write LLVM sample profile data --------------===//
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 implements the class that writes LLVM sample profiles. It
11 // supports two file formats: text and binary. The textual representation
12 // is useful for debugging and testing purposes. The binary representation
13 // is more compact, resulting in smaller file sizes. However, they can
14 // both be used interchangeably.
15 //
16 // See lib/ProfileData/SampleProfReader.cpp for documentation on each of the
17 // supported formats.
18 //
19 //===----------------------------------------------------------------------===//
20 
21 #include "llvm/ProfileData/SampleProfWriter.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/ErrorOr.h"
24 #include "llvm/Support/LEB128.h"
25 #include "llvm/Support/LineIterator.h"
26 #include "llvm/Support/MemoryBuffer.h"
27 #include "llvm/Support/Regex.h"
28 
29 using namespace llvm::sampleprof;
30 using namespace llvm;
31 
32 /// \brief Write samples to a text file.
33 ///
34 /// Note: it may be tempting to implement this in terms of
35 /// FunctionSamples::print().  Please don't.  The dump functionality is intended
36 /// for debugging and has no specified form.
37 ///
38 /// The format used here is more structured and deliberate because
39 /// it needs to be parsed by the SampleProfileReaderText class.
40 std::error_code SampleProfileWriterText::write(StringRef FName,
41                                                const FunctionSamples &S) {
42   OS << FName << ":" << S.getTotalSamples();
43   if (Indent == 0)
44     OS << ":" << S.getHeadSamples();
45   OS << "\n";
46 
47   SampleSorter<LineLocation, SampleRecord> SortedSamples(S.getBodySamples());
48   for (const auto &I : SortedSamples.get()) {
49     LineLocation Loc = I->first;
50     const SampleRecord &Sample = I->second;
51     OS.indent(Indent + 1);
52     if (Loc.Discriminator == 0)
53       OS << Loc.LineOffset << ": ";
54     else
55       OS << Loc.LineOffset << "." << Loc.Discriminator << ": ";
56 
57     OS << Sample.getSamples();
58 
59     for (const auto &J : Sample.getCallTargets())
60       OS << " " << J.first() << ":" << J.second;
61     OS << "\n";
62   }
63 
64   SampleSorter<CallsiteLocation, FunctionSamples> SortedCallsiteSamples(
65       S.getCallsiteSamples());
66   Indent += 1;
67   for (const auto &I : SortedCallsiteSamples.get()) {
68     CallsiteLocation Loc = I->first;
69     const FunctionSamples &CalleeSamples = I->second;
70     OS.indent(Indent);
71     if (Loc.Discriminator == 0)
72       OS << Loc.LineOffset << ": ";
73     else
74       OS << Loc.LineOffset << "." << Loc.Discriminator << ": ";
75     if (std::error_code EC = write(Loc.CalleeName, CalleeSamples))
76       return EC;
77   }
78   Indent -= 1;
79 
80   return sampleprof_error::success;
81 }
82 
83 std::error_code SampleProfileWriterBinary::writeNameIdx(StringRef FName) {
84   const auto &ret = NameTable.find(FName);
85   if (ret == NameTable.end())
86     return sampleprof_error::truncated_name_table;
87   encodeULEB128(ret->second, OS);
88   return sampleprof_error::success;
89 }
90 
91 void SampleProfileWriterBinary::addName(StringRef FName) {
92   auto NextIdx = NameTable.size();
93   NameTable.insert(std::make_pair(FName, NextIdx));
94 }
95 
96 void SampleProfileWriterBinary::addNames(const FunctionSamples &S) {
97   // Add all the names in indirect call targets.
98   for (const auto &I : S.getBodySamples()) {
99     const SampleRecord &Sample = I.second;
100     for (const auto &J : Sample.getCallTargets())
101       addName(J.first());
102   }
103 
104   // Recursively add all the names for inlined callsites.
105   for (const auto &J : S.getCallsiteSamples()) {
106     CallsiteLocation Loc = J.first;
107     const FunctionSamples &CalleeSamples = J.second;
108     addName(Loc.CalleeName);
109     addNames(CalleeSamples);
110   }
111 }
112 
113 std::error_code SampleProfileWriterBinary::writeHeader(
114     const StringMap<FunctionSamples> &ProfileMap) {
115   // Write file magic identifier.
116   encodeULEB128(SPMagic(), OS);
117   encodeULEB128(SPVersion(), OS);
118 
119   // Generate the name table for all the functions referenced in the profile.
120   for (const auto &I : ProfileMap) {
121     addName(I.first());
122     addNames(I.second);
123   }
124 
125   // Write out the name table.
126   encodeULEB128(NameTable.size(), OS);
127   for (auto N : NameTable) {
128     OS << N.first;
129     encodeULEB128(0, OS);
130   }
131 
132   return sampleprof_error::success;
133 }
134 
135 std::error_code SampleProfileWriterBinary::writeBody(StringRef FName,
136                                                      const FunctionSamples &S) {
137   if (std::error_code EC = writeNameIdx(FName))
138     return EC;
139 
140   encodeULEB128(S.getTotalSamples(), OS);
141 
142   // Emit all the body samples.
143   encodeULEB128(S.getBodySamples().size(), OS);
144   for (const auto &I : S.getBodySamples()) {
145     LineLocation Loc = I.first;
146     const SampleRecord &Sample = I.second;
147     encodeULEB128(Loc.LineOffset, OS);
148     encodeULEB128(Loc.Discriminator, OS);
149     encodeULEB128(Sample.getSamples(), OS);
150     encodeULEB128(Sample.getCallTargets().size(), OS);
151     for (const auto &J : Sample.getCallTargets()) {
152       StringRef Callee = J.first();
153       uint64_t CalleeSamples = J.second;
154       if (std::error_code EC = writeNameIdx(Callee))
155         return EC;
156       encodeULEB128(CalleeSamples, OS);
157     }
158   }
159 
160   // Recursively emit all the callsite samples.
161   encodeULEB128(S.getCallsiteSamples().size(), OS);
162   for (const auto &J : S.getCallsiteSamples()) {
163     CallsiteLocation Loc = J.first;
164     const FunctionSamples &CalleeSamples = J.second;
165     encodeULEB128(Loc.LineOffset, OS);
166     encodeULEB128(Loc.Discriminator, OS);
167     if (std::error_code EC = writeBody(Loc.CalleeName, CalleeSamples))
168       return EC;
169   }
170 
171   return sampleprof_error::success;
172 }
173 
174 /// \brief Write samples of a top-level function to a binary file.
175 ///
176 /// \returns true if the samples were written successfully, false otherwise.
177 std::error_code SampleProfileWriterBinary::write(StringRef FName,
178                                                  const FunctionSamples &S) {
179   encodeULEB128(S.getHeadSamples(), OS);
180   return writeBody(FName, S);
181 }
182 
183 /// \brief Create a sample profile writer based on the specified format.
184 ///
185 /// \param Filename The file to create.
186 ///
187 /// \param Writer The writer to instantiate according to the specified format.
188 ///
189 /// \param Format Encoding format for the profile file.
190 ///
191 /// \returns an error code indicating the status of the created writer.
192 ErrorOr<std::unique_ptr<SampleProfileWriter>>
193 SampleProfileWriter::create(StringRef Filename, SampleProfileFormat Format) {
194   std::error_code EC;
195   std::unique_ptr<SampleProfileWriter> Writer;
196 
197   if (Format == SPF_Binary)
198     Writer.reset(new SampleProfileWriterBinary(Filename, EC));
199   else if (Format == SPF_Text)
200     Writer.reset(new SampleProfileWriterText(Filename, EC));
201   else if (Format == SPF_GCC)
202     EC = sampleprof_error::unsupported_writing_format;
203   else
204     EC = sampleprof_error::unrecognized_format;
205 
206   if (EC)
207     return EC;
208 
209   return std::move(Writer);
210 }
211