1 //===- SampleProfReader.h - Read 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 contains definitions needed for reading sample profiles.
11 //
12 //===----------------------------------------------------------------------===//
13 #ifndef LLVM_PROFILEDATA_SAMPLEPROFREADER_H
14 #define LLVM_PROFILEDATA_SAMPLEPROFREADER_H
15 
16 #include "llvm/ADT/DenseMap.h"
17 #include "llvm/ADT/StringMap.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/ADT/Twine.h"
20 #include "llvm/IR/DiagnosticInfo.h"
21 #include "llvm/IR/Function.h"
22 #include "llvm/IR/LLVMContext.h"
23 #include "llvm/ProfileData/SampleProf.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/ErrorOr.h"
27 #include "llvm/Support/MemoryBuffer.h"
28 #include "llvm/Support/raw_ostream.h"
29 
30 namespace llvm {
31 
32 namespace sampleprof {
33 
34 /// \brief Sample-based profile reader.
35 ///
36 /// Each profile contains sample counts for all the functions
37 /// executed. Inside each function, statements are annotated with the
38 /// collected samples on all the instructions associated with that
39 /// statement.
40 ///
41 /// For this to produce meaningful data, the program needs to be
42 /// compiled with some debug information (at minimum, line numbers:
43 /// -gline-tables-only). Otherwise, it will be impossible to match IR
44 /// instructions to the line numbers collected by the profiler.
45 ///
46 /// From the profile file, we are interested in collecting the
47 /// following information:
48 ///
49 /// * A list of functions included in the profile (mangled names).
50 ///
51 /// * For each function F:
52 ///   1. The total number of samples collected in F.
53 ///
54 ///   2. The samples collected at each line in F. To provide some
55 ///      protection against source code shuffling, line numbers should
56 ///      be relative to the start of the function.
57 ///
58 /// The reader supports two file formats: text and binary. The text format
59 /// is useful for debugging and testing, while the binary format is more
60 /// compact. They can both be used interchangeably.
61 class SampleProfileReader {
62 public:
SampleProfileReader(std::unique_ptr<MemoryBuffer> B,LLVMContext & C)63   SampleProfileReader(std::unique_ptr<MemoryBuffer> B, LLVMContext &C)
64       : Profiles(0), Ctx(C), Buffer(std::move(B)) {}
65 
~SampleProfileReader()66   virtual ~SampleProfileReader() {}
67 
68   /// \brief Read and validate the file header.
69   virtual std::error_code readHeader() = 0;
70 
71   /// \brief Read sample profiles from the associated file.
72   virtual std::error_code read() = 0;
73 
74   /// \brief Print the profile for \p FName on stream \p OS.
75   void dumpFunctionProfile(StringRef FName, raw_ostream &OS = dbgs());
76 
77   /// \brief Print all the profiles on stream \p OS.
78   void dump(raw_ostream &OS = dbgs());
79 
80   /// \brief Return the samples collected for function \p F.
getSamplesFor(const Function & F)81   FunctionSamples *getSamplesFor(const Function &F) {
82     return &Profiles[F.getName()];
83   }
84 
85   /// \brief Return all the profiles.
getProfiles()86   StringMap<FunctionSamples> &getProfiles() { return Profiles; }
87 
88   /// \brief Report a parse error message.
reportParseError(int64_t LineNumber,Twine Msg)89   void reportParseError(int64_t LineNumber, Twine Msg) const {
90     Ctx.diagnose(DiagnosticInfoSampleProfile(Buffer->getBufferIdentifier(),
91                                              LineNumber, Msg));
92   }
93 
94   /// \brief Create a sample profile reader appropriate to the file format.
95   static ErrorOr<std::unique_ptr<SampleProfileReader>>
96   create(StringRef Filename, LLVMContext &C);
97 
98 protected:
99   /// \brief Map every function to its associated profile.
100   ///
101   /// The profile of every function executed at runtime is collected
102   /// in the structure FunctionSamples. This maps function objects
103   /// to their corresponding profiles.
104   StringMap<FunctionSamples> Profiles;
105 
106   /// \brief LLVM context used to emit diagnostics.
107   LLVMContext &Ctx;
108 
109   /// \brief Memory buffer holding the profile file.
110   std::unique_ptr<MemoryBuffer> Buffer;
111 };
112 
113 class SampleProfileReaderText : public SampleProfileReader {
114 public:
SampleProfileReaderText(std::unique_ptr<MemoryBuffer> B,LLVMContext & C)115   SampleProfileReaderText(std::unique_ptr<MemoryBuffer> B, LLVMContext &C)
116       : SampleProfileReader(std::move(B), C) {}
117 
118   /// \brief Read and validate the file header.
readHeader()119   std::error_code readHeader() override { return sampleprof_error::success; }
120 
121   /// \brief Read sample profiles from the associated file.
122   std::error_code read() override;
123 };
124 
125 class SampleProfileReaderBinary : public SampleProfileReader {
126 public:
SampleProfileReaderBinary(std::unique_ptr<MemoryBuffer> B,LLVMContext & C)127   SampleProfileReaderBinary(std::unique_ptr<MemoryBuffer> B, LLVMContext &C)
128       : SampleProfileReader(std::move(B), C), Data(nullptr), End(nullptr) {}
129 
130   /// \brief Read and validate the file header.
131   std::error_code readHeader() override;
132 
133   /// \brief Read sample profiles from the associated file.
134   std::error_code read() override;
135 
136   /// \brief Return true if \p Buffer is in the format supported by this class.
137   static bool hasFormat(const MemoryBuffer &Buffer);
138 
139 protected:
140   /// \brief Read a numeric value of type T from the profile.
141   ///
142   /// If an error occurs during decoding, a diagnostic message is emitted and
143   /// EC is set.
144   ///
145   /// \returns the read value.
146   template <typename T> ErrorOr<T> readNumber();
147 
148   /// \brief Read a string from the profile.
149   ///
150   /// If an error occurs during decoding, a diagnostic message is emitted and
151   /// EC is set.
152   ///
153   /// \returns the read value.
154   ErrorOr<StringRef> readString();
155 
156   /// \brief Return true if we've reached the end of file.
at_eof()157   bool at_eof() const { return Data >= End; }
158 
159   /// \brief Points to the current location in the buffer.
160   const uint8_t *Data;
161 
162   /// \brief Points to the end of the buffer.
163   const uint8_t *End;
164 };
165 
166 } // End namespace sampleprof
167 
168 } // End namespace llvm
169 
170 #endif // LLVM_PROFILEDATA_SAMPLEPROFREADER_H
171