LLVM  3.7.0
Compression.cpp
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1 //===--- Compression.cpp - Compression implementation ---------------------===//
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 compression functions.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 #include "llvm/ADT/SmallVector.h"
16 #include "llvm/ADT/StringRef.h"
17 #include "llvm/Config/config.h"
18 #include "llvm/Support/Compiler.h"
20 #if LLVM_ENABLE_ZLIB == 1 && HAVE_ZLIB_H
21 #include <zlib.h>
22 #endif
23 
24 using namespace llvm;
25 
26 #if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
28  switch (Level) {
29  case zlib::NoCompression: return 0;
30  case zlib::BestSpeedCompression: return 1;
31  case zlib::DefaultCompression: return Z_DEFAULT_COMPRESSION;
32  case zlib::BestSizeCompression: return 9;
33  }
34  llvm_unreachable("Invalid zlib::CompressionLevel!");
35 }
36 
37 static zlib::Status encodeZlibReturnValue(int ReturnValue) {
38  switch (ReturnValue) {
39  case Z_OK: return zlib::StatusOK;
40  case Z_MEM_ERROR: return zlib::StatusOutOfMemory;
41  case Z_BUF_ERROR: return zlib::StatusBufferTooShort;
42  case Z_STREAM_ERROR: return zlib::StatusInvalidArg;
43  case Z_DATA_ERROR: return zlib::StatusInvalidData;
44  default: llvm_unreachable("unknown zlib return status!");
45  }
46 }
47 
48 bool zlib::isAvailable() { return true; }
50  SmallVectorImpl<char> &CompressedBuffer,
52  unsigned long CompressedSize = ::compressBound(InputBuffer.size());
53  CompressedBuffer.resize(CompressedSize);
54  int CLevel = encodeZlibCompressionLevel(Level);
55  Status Res = encodeZlibReturnValue(::compress2(
56  (Bytef *)CompressedBuffer.data(), &CompressedSize,
57  (const Bytef *)InputBuffer.data(), InputBuffer.size(), CLevel));
58  // Tell MemorySanitizer that zlib output buffer is fully initialized.
59  // This avoids a false report when running LLVM with uninstrumented ZLib.
60  __msan_unpoison(CompressedBuffer.data(), CompressedSize);
61  CompressedBuffer.resize(CompressedSize);
62  return Res;
63 }
64 
66  SmallVectorImpl<char> &UncompressedBuffer,
67  size_t UncompressedSize) {
68  UncompressedBuffer.resize(UncompressedSize);
70  (Bytef *)UncompressedBuffer.data(), (uLongf *)&UncompressedSize,
71  (const Bytef *)InputBuffer.data(), InputBuffer.size()));
72  // Tell MemorySanitizer that zlib output buffer is fully initialized.
73  // This avoids a false report when running LLVM with uninstrumented ZLib.
74  __msan_unpoison(UncompressedBuffer.data(), UncompressedSize);
75  UncompressedBuffer.resize(UncompressedSize);
76  return Res;
77 }
78 
79 uint32_t zlib::crc32(StringRef Buffer) {
80  return ::crc32(0, (const Bytef *)Buffer.data(), Buffer.size());
81 }
82 
83 #else
84 bool zlib::isAvailable() { return false; }
86  SmallVectorImpl<char> &CompressedBuffer,
89 }
91  SmallVectorImpl<char> &UncompressedBuffer,
92  size_t UncompressedSize) {
94 }
95 uint32_t zlib::crc32(StringRef Buffer) {
96  llvm_unreachable("zlib::crc32 is unavailable");
97 }
98 #endif
99 
static int encodeZlibCompressionLevel(zlib::CompressionLevel Level)
Definition: Compression.cpp:27
size_t size() const
size - Get the string size.
Definition: StringRef.h:113
static zlib::Status encodeZlibReturnValue(int ReturnValue)
Definition: Compression.cpp:37
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
Status compress(StringRef InputBuffer, SmallVectorImpl< char > &CompressedBuffer, CompressionLevel Level=DefaultCompression)
Definition: Compression.cpp:49
const char * data() const
data - Get a pointer to the start of the string (which may not be null terminated).
Definition: StringRef.h:107
bool isAvailable()
Definition: Compression.cpp:48
#define __msan_unpoison(p, size)
Definition: Compiler.h:329
uint32_t crc32(StringRef Buffer)
Definition: Compression.cpp:79
Status uncompress(StringRef InputBuffer, SmallVectorImpl< char > &UncompressedBuffer, size_t UncompressedSize)
Definition: Compression.cpp:65
pointer data()
Return a pointer to the vector's buffer, even if empty().
Definition: SmallVector.h:134
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:40
void resize(size_type N)
Definition: SmallVector.h:376