1 //===- lib/Support/Compressor.cpp -------------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Reid Spencer and is distributed under the
6 // University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the llvm::Compressor class, an abstraction for memory
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Config/config.h"
16 #include "llvm/Support/Compressor.h"
17 #include "llvm/ADT/StringExtras.h"
21 #include "bzip2/bzlib.h"
24 enum CompressionTypes {
26 COMP_TYPE_BZIP2 = '2',
29 static int getdata(char*& buffer, size_t &size,
30 llvm::Compressor::OutputDataCallback* cb, void* context) {
33 int result = (*cb)(buffer, size, context);
34 assert(buffer != 0 && "Invalid result from Compressor callback");
35 assert(size != 0 && "Invalid result from Compressor callback");
39 static int getdata_uns(char*& buffer, unsigned &size,
40 llvm::Compressor::OutputDataCallback* cb, void* context)
43 int Res = getdata(buffer, SizeOut, cb, context);
48 //===----------------------------------------------------------------------===//
49 //=== NULLCOMP - a compression like set of routines that just copies data
50 //=== without doing any compression. This is provided so that if the
51 //=== configured environment doesn't have a compression library the
52 //=== program can still work, albeit using more data/memory.
53 //===----------------------------------------------------------------------===//
55 struct NULLCOMP_stream {
56 // User provided fields
63 size_t output_count; // Total count of output bytes
66 static void NULLCOMP_init(NULLCOMP_stream* s) {
70 static bool NULLCOMP_compress(NULLCOMP_stream* s) {
71 assert(s && "Invalid NULLCOMP_stream");
72 assert(s->next_in != 0);
73 assert(s->next_out != 0);
74 assert(s->avail_in >= 1);
75 assert(s->avail_out >= 1);
77 if (s->avail_out >= s->avail_in) {
78 ::memcpy(s->next_out, s->next_in, s->avail_in);
79 s->output_count += s->avail_in;
80 s->avail_out -= s->avail_in;
81 s->next_in += s->avail_in;
85 ::memcpy(s->next_out, s->next_in, s->avail_out);
86 s->output_count += s->avail_out;
87 s->avail_in -= s->avail_out;
88 s->next_in += s->avail_out;
94 static bool NULLCOMP_decompress(NULLCOMP_stream* s) {
95 assert(s && "Invalid NULLCOMP_stream");
96 assert(s->next_in != 0);
97 assert(s->next_out != 0);
98 assert(s->avail_in >= 1);
99 assert(s->avail_out >= 1);
101 if (s->avail_out >= s->avail_in) {
102 ::memcpy(s->next_out, s->next_in, s->avail_in);
103 s->output_count += s->avail_in;
104 s->avail_out -= s->avail_in;
105 s->next_in += s->avail_in;
109 ::memcpy(s->next_out, s->next_in, s->avail_out);
110 s->output_count += s->avail_out;
111 s->avail_in -= s->avail_out;
112 s->next_in += s->avail_out;
118 static void NULLCOMP_end(NULLCOMP_stream* strm) {
123 /// This structure is only used when a bytecode file is compressed.
124 /// As bytecode is being decompressed, the memory buffer might need
125 /// to be reallocated. The buffer allocation is handled in a callback
126 /// and this structure is needed to retain information across calls
128 /// @brief An internal buffer object used for handling decompression
129 struct BufferContext {
132 BufferContext(size_t compressedSize) {
133 // Null to indicate malloc of a new block
136 // Compute the initial length of the uncompression buffer. Note that this
137 // is twice the length of the compressed buffer and will be doubled again
138 // in the callback for an initial allocation of 4x compressedSize. This
139 // calculation is based on the typical compression ratio of bzip2 on LLVM
140 // bytecode files which typically ranges in the 50%-75% range. Since we
141 // typically get at least 50%, doubling is insufficient. By using a 4x
142 // multiplier on the first allocation, we minimize the impact of having to
143 // copy the buffer on reallocation.
144 size = compressedSize*2;
147 /// trimTo - Reduce the size of the buffer down to the specified amount. This
148 /// is useful after have read in the bytecode file to discard extra unused
151 void trimTo(size_t NewSize) {
152 buff = (char*)::realloc(buff, NewSize);
156 /// This function handles allocation of the buffer used for decompression of
157 /// compressed bytecode files. It is called by Compressor::decompress which is
158 /// called by BytecodeReader::ParseBytecode.
159 static size_t callback(char*&buff, size_t &sz, void* ctxt){
160 // Case the context variable to our BufferContext
161 BufferContext* bc = reinterpret_cast<BufferContext*>(ctxt);
163 // Compute the new, doubled, size of the block
164 size_t new_size = bc->size * 2;
166 // Extend or allocate the block (realloc(0,n) == malloc(n))
167 char* new_buff = (char*) ::realloc(bc->buff, new_size);
169 // Figure out what to return to the Compressor. If this is the first call,
170 // then bc->buff will be null. In this case we want to return the entire
171 // buffer because there was no previous allocation. Otherwise, when the
172 // buffer is reallocated, we save the new base pointer in the
173 // BufferContext.buff field but return the address of only the extension,
174 // mid-way through the buffer (since its size was doubled). Furthermore,
175 // the sz result must be 1/2 the total size of the buffer.
176 if (bc->buff == 0 ) {
177 buff = bc->buff = new_buff;
181 buff = new_buff + bc->size;
185 // Retain the size of the allocated block
188 // Make sure we fail (return 1) if we didn't get any memory.
189 return (bc->buff == 0 ? 1 : 0);
193 } // end anonymous namespace
198 // This structure retains the context when compressing the bytecode file. The
199 // WriteCompressedData function below uses it to keep track of the previously
200 // filled chunk of memory (which it writes) and how many bytes have been
202 struct WriterContext {
203 // Initialize the context
204 WriterContext(std::ostream*OS, size_t CS)
205 : chunk(0), sz(0), written(0), compSize(CS), Out(OS) {}
207 // Make sure we clean up memory
214 void write(size_t size = 0) {
215 size_t write_size = (size == 0 ? sz : size);
216 Out->write(chunk,write_size);
217 written += write_size;
223 // This function is a callback used by the Compressor::compress function to
224 // allocate memory for the compression buffer. This function fulfills that
225 // responsibility but also writes the previous (now filled) buffer out to the
227 static size_t callback(char*& buffer, size_t &size, void* context) {
228 // Cast the context to the structure it must point to.
229 WriterContext* ctxt = reinterpret_cast<WriterContext*>(context);
231 // If there's a previously allocated chunk, it must now be filled with
232 // compressed data, so we write it out and deallocate it.
233 if (ctxt->chunk != 0 && ctxt->sz > 0 ) {
237 // Compute the size of the next chunk to allocate. We attempt to allocate
238 // enough memory to handle the compression in a single memory allocation. In
239 // general, the worst we do on compression of bytecode is about 50% so we
240 // conservatively estimate compSize / 2 as the size needed for the
241 // compression buffer. compSize is the size of the compressed data, provided
242 // by WriteBytecodeToFile.
243 size = ctxt->sz = ctxt->compSize / 2;
245 // Allocate the chunks
246 buffer = ctxt->chunk = new char [size];
248 // We must return 1 if the allocation failed so that the Compressor knows
249 // not to use the buffer pointer.
250 return (ctxt->chunk == 0 ? 1 : 0);
253 char* chunk; // pointer to the chunk of memory filled by compression
254 size_t sz; // size of chunk
255 size_t written; // aggregate total of bytes written in all chunks
256 size_t compSize; // size of the uncompressed buffer
257 std::ostream* Out; // The stream we write the data to.
260 } // end anonymous namespace
262 // Compress in one of three ways
263 size_t Compressor::compress(const char* in, size_t size,
264 OutputDataCallback* cb, void* context) {
265 assert(in && "Can't compress null buffer");
266 assert(size && "Can't compress empty buffer");
267 assert(cb && "Can't compress without a callback function");
271 // For small files, we just don't bother compressing. bzip2 isn't very good
272 // with tiny files and can actually make the file larger, so we just avoid
274 if (size > 64*1024) {
275 // Set up the bz_stream
280 bzdata.next_in = (char*)in;
281 bzdata.avail_in = size;
283 bzdata.avail_out = 0;
284 switch ( BZ2_bzCompressInit(&bzdata, 5, 0, 100) ) {
285 case BZ_CONFIG_ERROR: throw std::string("bzip2 library mis-compiled");
286 case BZ_PARAM_ERROR: throw std::string("Compressor internal error");
287 case BZ_MEM_ERROR: throw std::string("Out of memory");
293 // Get a block of memory
294 if (0 != getdata_uns(bzdata.next_out, bzdata.avail_out,cb,context)) {
295 BZ2_bzCompressEnd(&bzdata);
296 throw std::string("Can't allocate output buffer");
299 // Put compression code in first byte
300 (*bzdata.next_out++) = COMP_TYPE_BZIP2;
304 int bzerr = BZ_FINISH_OK;
305 while (BZ_FINISH_OK == (bzerr = BZ2_bzCompress(&bzdata, BZ_FINISH))) {
306 if (0 != getdata_uns(bzdata.next_out, bzdata.avail_out,cb,context)) {
307 BZ2_bzCompressEnd(&bzdata);
308 throw std::string("Can't allocate output buffer");
312 case BZ_SEQUENCE_ERROR:
313 case BZ_PARAM_ERROR: throw std::string("Param/Sequence error");
315 case BZ_STREAM_END: break;
316 default: throw std::string("Oops: ") + utostr(unsigned(bzerr));
320 result = bzdata.total_out_lo32 + 1;
321 if (sizeof(size_t) == sizeof(uint64_t))
322 result |= static_cast<uint64_t>(bzdata.total_out_hi32) << 32;
324 BZ2_bzCompressEnd(&bzdata);
326 // Do null compression, for small files
327 NULLCOMP_stream sdata;
328 sdata.next_in = (char*)in;
329 sdata.avail_in = size;
330 NULLCOMP_init(&sdata);
332 if (0 != getdata(sdata.next_out, sdata.avail_out,cb,context)) {
333 throw std::string("Can't allocate output buffer");
336 *(sdata.next_out++) = COMP_TYPE_NONE;
339 while (!NULLCOMP_compress(&sdata)) {
340 if (0 != getdata(sdata.next_out, sdata.avail_out,cb,context)) {
341 throw std::string("Can't allocate output buffer");
345 result = sdata.output_count + 1;
346 NULLCOMP_end(&sdata);
351 size_t Compressor::compressToNewBuffer(const char* in, size_t size, char*&out) {
352 BufferContext bc(size);
353 size_t result = compress(in,size,BufferContext::callback,(void*)&bc);
360 Compressor::compressToStream(const char*in, size_t size, std::ostream& out) {
361 // Set up the context and writer
362 WriterContext ctxt(&out, size / 2);
364 // Compress everything after the magic number (which we'll alter).
365 size_t zipSize = Compressor::compress(in,size,
366 WriterContext::callback, (void*)&ctxt);
369 ctxt.write(zipSize - ctxt.written);
374 // Decompress in one of three ways
375 size_t Compressor::decompress(const char *in, size_t size,
376 OutputDataCallback* cb, void* context) {
377 assert(in && "Can't decompress null buffer");
378 assert(size > 1 && "Can't decompress empty buffer");
379 assert(cb && "Can't decompress without a callback function");
384 case COMP_TYPE_BZIP2: {
385 // Set up the bz_stream
390 bzdata.next_in = (char*)in;
391 bzdata.avail_in = size - 1;
393 bzdata.avail_out = 0;
394 switch ( BZ2_bzDecompressInit(&bzdata, 0, 0) ) {
395 case BZ_CONFIG_ERROR: throw std::string("bzip2 library mis-compiled");
396 case BZ_PARAM_ERROR: throw std::string("Compressor internal error");
397 case BZ_MEM_ERROR: throw std::string("Out of memory");
403 // Get a block of memory
404 if (0 != getdata_uns(bzdata.next_out, bzdata.avail_out,cb,context)) {
405 BZ2_bzDecompressEnd(&bzdata);
406 throw std::string("Can't allocate output buffer");
411 while (BZ_OK == (bzerr = BZ2_bzDecompress(&bzdata))) {
412 if (0 != getdata_uns(bzdata.next_out, bzdata.avail_out,cb,context)) {
413 BZ2_bzDecompressEnd(&bzdata);
414 throw std::string("Can't allocate output buffer");
419 case BZ_PARAM_ERROR: throw std::string("Compressor internal error");
420 case BZ_MEM_ERROR: throw std::string("Out of memory");
421 case BZ_DATA_ERROR: throw std::string("Data integrity error");
422 case BZ_DATA_ERROR_MAGIC:throw std::string("Data is not BZIP2");
423 default: throw("Ooops");
429 result = bzdata.total_out_lo32;
430 if (sizeof(size_t) == sizeof(uint64_t))
431 result |= (static_cast<uint64_t>(bzdata.total_out_hi32) << 32);
432 BZ2_bzDecompressEnd(&bzdata);
436 case COMP_TYPE_NONE: {
437 NULLCOMP_stream sdata;
438 sdata.next_in = (char*)in;
439 sdata.avail_in = size - 1;
440 NULLCOMP_init(&sdata);
442 if (0 != getdata(sdata.next_out, sdata.avail_out,cb,context)) {
443 throw std::string("Can't allocate output buffer");
446 while (!NULLCOMP_decompress(&sdata)) {
447 if (0 != getdata(sdata.next_out, sdata.avail_out,cb,context)) {
448 throw std::string("Can't allocate output buffer");
452 result = sdata.output_count;
453 NULLCOMP_end(&sdata);
458 throw std::string("Unknown type of compressed data");
465 Compressor::decompressToNewBuffer(const char* in, size_t size, char*&out) {
466 BufferContext bc(size);
467 size_t result = decompress(in,size,BufferContext::callback,(void*)&bc);
473 Compressor::decompressToStream(const char*in, size_t size, std::ostream& out){
474 // Set up the context and writer
475 WriterContext ctxt(&out,size / 2);
477 // Compress everything after the magic number (which we'll alter)
478 size_t zipSize = Compressor::decompress(in,size,
479 WriterContext::callback, (void*)&ctxt);
482 ctxt.write(zipSize - ctxt.written);