llvm-6502/lib/Support/Compressor.cpp
Chris Lattner 25dc891a3d Do not throw away bits for no reason
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19378 91177308-0d34-0410-b5e6-96231b3b80d8
2005-01-08 19:32:59 +00:00

466 lines
15 KiB
C++

//===- lib/Support/Compressor.cpp -------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Reid Spencer and is distributed under the
// University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the llvm::Compressor class, an abstraction for memory
// block compression.
//
//===----------------------------------------------------------------------===//
#include "llvm/Config/config.h"
#include "llvm/Support/Compressor.h"
#include "llvm/ADT/StringExtras.h"
#include <cassert>
#include <string>
#include "bzip2/bzlib.h"
namespace {
enum CompressionTypes {
COMP_TYPE_NONE = '0',
COMP_TYPE_BZIP2 = '2',
};
inline int getdata(char*& buffer, unsigned& size,
llvm::Compressor::OutputDataCallback* cb, void* context) {
buffer = 0;
size = 0;
int result = (*cb)(buffer, size, context);
assert(buffer != 0 && "Invalid result from Compressor callback");
assert(size != 0 && "Invalid result from Compressor callback");
return result;
}
//===----------------------------------------------------------------------===//
//=== NULLCOMP - a compression like set of routines that just copies data
//=== without doing any compression. This is provided so that if the
//=== configured environment doesn't have a compression library the
//=== program can still work, albeit using more data/memory.
//===----------------------------------------------------------------------===//
struct NULLCOMP_stream {
// User provided fields
char* next_in;
unsigned avail_in;
char* next_out;
unsigned avail_out;
// Information fields
uint64_t output_count; // Total count of output bytes
};
void NULLCOMP_init(NULLCOMP_stream* s) {
s->output_count = 0;
}
bool NULLCOMP_compress(NULLCOMP_stream* s) {
assert(s && "Invalid NULLCOMP_stream");
assert(s->next_in != 0);
assert(s->next_out != 0);
assert(s->avail_in >= 1);
assert(s->avail_out >= 1);
if (s->avail_out >= s->avail_in) {
::memcpy(s->next_out, s->next_in, s->avail_in);
s->output_count += s->avail_in;
s->avail_out -= s->avail_in;
s->next_in += s->avail_in;
s->avail_in = 0;
return true;
} else {
::memcpy(s->next_out, s->next_in, s->avail_out);
s->output_count += s->avail_out;
s->avail_in -= s->avail_out;
s->next_in += s->avail_out;
s->avail_out = 0;
return false;
}
}
bool NULLCOMP_decompress(NULLCOMP_stream* s) {
assert(s && "Invalid NULLCOMP_stream");
assert(s->next_in != 0);
assert(s->next_out != 0);
assert(s->avail_in >= 1);
assert(s->avail_out >= 1);
if (s->avail_out >= s->avail_in) {
::memcpy(s->next_out, s->next_in, s->avail_in);
s->output_count += s->avail_in;
s->avail_out -= s->avail_in;
s->next_in += s->avail_in;
s->avail_in = 0;
return true;
} else {
::memcpy(s->next_out, s->next_in, s->avail_out);
s->output_count += s->avail_out;
s->avail_in -= s->avail_out;
s->next_in += s->avail_out;
s->avail_out = 0;
return false;
}
}
void NULLCOMP_end(NULLCOMP_stream* strm) {
}
/// This structure is only used when a bytecode file is compressed.
/// As bytecode is being decompressed, the memory buffer might need
/// to be reallocated. The buffer allocation is handled in a callback
/// and this structure is needed to retain information across calls
/// to the callback.
/// @brief An internal buffer object used for handling decompression
struct BufferContext {
char* buff;
unsigned size;
BufferContext(unsigned compressedSize ) {
// Null to indicate malloc of a new block
buff = 0;
// Compute the initial length of the uncompression buffer. Note that this
// is twice the length of the compressed buffer and will be doubled again
// in the callback for an initial allocation of 4x compressedSize. This
// calculation is based on the typical compression ratio of bzip2 on LLVM
// bytecode files which typically ranges in the 50%-75% range. Since we
// tyipcally get at least 50%, doubling is insufficient. By using a 4x
// multiplier on the first allocation, we minimize the impact of having to
// copy the buffer on reallocation.
size = compressedSize*2;
}
/// This function handles allocation of the buffer used for decompression of
/// compressed bytecode files. It is called by Compressor::decompress which is
/// called by BytecodeReader::ParseBytecode.
static unsigned callback(char*&buff, unsigned& sz, void* ctxt){
// Case the context variable to our BufferContext
BufferContext* bc = reinterpret_cast<BufferContext*>(ctxt);
// Compute the new, doubled, size of the block
unsigned new_size = bc->size * 2;
// Extend or allocate the block (realloc(0,n) == malloc(n))
char* new_buff = (char*) ::realloc(bc->buff, new_size);
// Figure out what to return to the Compressor. If this is the first call,
// then bc->buff will be null. In this case we want to return the entire
// buffer because there was no previous allocation. Otherwise, when the
// buffer is reallocated, we save the new base pointer in the
// BufferContext.buff field but return the address of only the extension,
// mid-way through the buffer (since its size was doubled). Furthermore,
// the sz result must be 1/2 the total size of the buffer.
if (bc->buff == 0 ) {
buff = bc->buff = new_buff;
sz = new_size;
} else {
bc->buff = new_buff;
buff = new_buff + bc->size;
sz = bc->size;
}
// Retain the size of the allocated block
bc->size = new_size;
// Make sure we fail (return 1) if we didn't get any memory.
return (bc->buff == 0 ? 1 : 0);
}
};
// This structure retains the context when compressing the bytecode file. The
// WriteCompressedData function below uses it to keep track of the previously
// filled chunk of memory (which it writes) and how many bytes have been
// written.
struct WriterContext {
// Initialize the context
WriterContext(std::ostream*OS, unsigned CS)
: chunk(0), sz(0), written(0), compSize(CS), Out(OS) {}
// Make sure we clean up memory
~WriterContext() {
if (chunk)
delete [] chunk;
}
// Write the chunk
void write(unsigned size = 0) {
unsigned write_size = (size == 0 ? sz : size);
Out->write(chunk,write_size);
written += write_size;
delete [] chunk;
chunk = 0;
sz = 0;
}
// This function is a callback used by the Compressor::compress function to
// allocate memory for the compression buffer. This function fulfills that
// responsibility but also writes the previous (now filled) buffer out to the
// stream.
static unsigned callback(char*& buffer, unsigned& size, void* context) {
// Cast the context to the structure it must point to.
WriterContext* ctxt =
reinterpret_cast<WriterContext*>(context);
// If there's a previously allocated chunk, it must now be filled with
// compressed data, so we write it out and deallocate it.
if (ctxt->chunk != 0 && ctxt->sz > 0 ) {
ctxt->write();
}
// Compute the size of the next chunk to allocate. We attempt to allocate
// enough memory to handle the compression in a single memory allocation. In
// general, the worst we do on compression of bytecode is about 50% so we
// conservatively estimate compSize / 2 as the size needed for the
// compression buffer. compSize is the size of the compressed data, provided
// by WriteBytecodeToFile.
size = ctxt->sz = ctxt->compSize / 2;
// Allocate the chunks
buffer = ctxt->chunk = new char [size];
// We must return 1 if the allocation failed so that the Compressor knows
// not to use the buffer pointer.
return (ctxt->chunk == 0 ? 1 : 0);
}
char* chunk; // pointer to the chunk of memory filled by compression
unsigned sz; // size of chunk
unsigned written; // aggregate total of bytes written in all chunks
unsigned compSize; // size of the uncompressed buffer
std::ostream* Out; // The stream we write the data to.
};
}
namespace llvm {
// Compress in one of three ways
uint64_t Compressor::compress(const char* in, unsigned size,
OutputDataCallback* cb, void* context ) {
assert(in && "Can't compress null buffer");
assert(size && "Can't compress empty buffer");
assert(cb && "Can't compress without a callback function");
uint64_t result = 0;
// For small files, we just don't bother compressing. bzip2 isn't very good
// with tiny files and can actually make the file larger, so we just avoid
// it altogether.
if (size > 64*1024) {
// Set up the bz_stream
bz_stream bzdata;
bzdata.bzalloc = 0;
bzdata.bzfree = 0;
bzdata.opaque = 0;
bzdata.next_in = (char*)in;
bzdata.avail_in = size;
bzdata.next_out = 0;
bzdata.avail_out = 0;
switch ( BZ2_bzCompressInit(&bzdata, 5, 0, 100) ) {
case BZ_CONFIG_ERROR: throw std::string("bzip2 library mis-compiled");
case BZ_PARAM_ERROR: throw std::string("Compressor internal error");
case BZ_MEM_ERROR: throw std::string("Out of memory");
case BZ_OK:
default:
break;
}
// Get a block of memory
if (0 != getdata(bzdata.next_out, bzdata.avail_out,cb,context)) {
BZ2_bzCompressEnd(&bzdata);
throw std::string("Can't allocate output buffer");
}
// Put compression code in first byte
(*bzdata.next_out++) = COMP_TYPE_BZIP2;
bzdata.avail_out--;
// Compress it
int bzerr = BZ_FINISH_OK;
while (BZ_FINISH_OK == (bzerr = BZ2_bzCompress(&bzdata, BZ_FINISH))) {
if (0 != getdata(bzdata.next_out, bzdata.avail_out,cb,context)) {
BZ2_bzCompressEnd(&bzdata);
throw std::string("Can't allocate output buffer");
}
}
switch (bzerr) {
case BZ_SEQUENCE_ERROR:
case BZ_PARAM_ERROR: throw std::string("Param/Sequence error");
case BZ_FINISH_OK:
case BZ_STREAM_END: break;
default: throw std::string("Oops: ") + utostr(unsigned(bzerr));
}
// Finish
result = (static_cast<uint64_t>(bzdata.total_out_hi32) << 32) |
bzdata.total_out_lo32 + 1;
BZ2_bzCompressEnd(&bzdata);
} else {
// Do null compression, for small files
NULLCOMP_stream sdata;
sdata.next_in = (char*)in;
sdata.avail_in = size;
NULLCOMP_init(&sdata);
if (0 != getdata(sdata.next_out, sdata.avail_out,cb,context)) {
throw std::string("Can't allocate output buffer");
}
*(sdata.next_out++) = COMP_TYPE_NONE;
sdata.avail_out--;
while (!NULLCOMP_compress(&sdata)) {
if (0 != getdata(sdata.next_out, sdata.avail_out,cb,context)) {
throw std::string("Can't allocate output buffer");
}
}
result = sdata.output_count + 1;
NULLCOMP_end(&sdata);
}
return result;
}
uint64_t
Compressor::compressToNewBuffer(const char* in, unsigned size, char*&out) {
BufferContext bc(size);
uint64_t result = compress(in,size,BufferContext::callback,(void*)&bc);
out = bc.buff;
return result;
}
uint64_t
Compressor::compressToStream(const char*in, unsigned size, std::ostream& out) {
// Set up the context and writer
WriterContext ctxt(&out,size / 2);
// Compress everything after the magic number (which we'll alter)
uint64_t zipSize = Compressor::compress(in,size,
WriterContext::callback, (void*)&ctxt);
if (ctxt.chunk) {
ctxt.write(zipSize - ctxt.written);
}
return zipSize;
}
// Decompress in one of three ways
uint64_t Compressor::decompress(const char *in, unsigned size,
OutputDataCallback* cb, void* context) {
assert(in && "Can't decompress null buffer");
assert(size > 1 && "Can't decompress empty buffer");
assert(cb && "Can't decompress without a callback function");
uint64_t result = 0;
switch (*in++) {
case COMP_TYPE_BZIP2: {
// Set up the bz_stream
bz_stream bzdata;
bzdata.bzalloc = 0;
bzdata.bzfree = 0;
bzdata.opaque = 0;
bzdata.next_in = (char*)in;
bzdata.avail_in = size - 1;
bzdata.next_out = 0;
bzdata.avail_out = 0;
switch ( BZ2_bzDecompressInit(&bzdata, 0, 0) ) {
case BZ_CONFIG_ERROR: throw std::string("bzip2 library mis-compiled");
case BZ_PARAM_ERROR: throw std::string("Compressor internal error");
case BZ_MEM_ERROR: throw std::string("Out of memory");
case BZ_OK:
default:
break;
}
// Get a block of memory
if (0 != getdata(bzdata.next_out, bzdata.avail_out,cb,context)) {
BZ2_bzDecompressEnd(&bzdata);
throw std::string("Can't allocate output buffer");
}
// Decompress it
int bzerr = BZ_OK;
while (BZ_OK == (bzerr = BZ2_bzDecompress(&bzdata))) {
if (0 != getdata(bzdata.next_out, bzdata.avail_out,cb,context)) {
BZ2_bzDecompressEnd(&bzdata);
throw std::string("Can't allocate output buffer");
}
}
switch (bzerr) {
case BZ_PARAM_ERROR: throw std::string("Compressor internal error");
case BZ_MEM_ERROR: throw std::string("Out of memory");
case BZ_DATA_ERROR: throw std::string("Data integrity error");
case BZ_DATA_ERROR_MAGIC:throw std::string("Data is not BZIP2");
default: throw("Ooops");
case BZ_STREAM_END:
break;
}
// Finish
result = (static_cast<uint64_t>(bzdata.total_out_hi32) << 32) |
bzdata.total_out_lo32;
BZ2_bzDecompressEnd(&bzdata);
break;
}
case COMP_TYPE_NONE: {
NULLCOMP_stream sdata;
sdata.next_in = (char*)in;
sdata.avail_in = size - 1;
NULLCOMP_init(&sdata);
if (0 != getdata(sdata.next_out, sdata.avail_out,cb,context)) {
throw std::string("Can't allocate output buffer");
}
while (!NULLCOMP_decompress(&sdata)) {
if (0 != getdata(sdata.next_out, sdata.avail_out,cb,context)) {
throw std::string("Can't allocate output buffer");
}
}
result = sdata.output_count;
NULLCOMP_end(&sdata);
break;
}
default:
throw std::string("Unknown type of compressed data");
}
return result;
}
uint64_t
Compressor::decompressToNewBuffer(const char* in, unsigned size, char*&out) {
BufferContext bc(size);
unsigned result = decompress(in,size,BufferContext::callback,(void*)&bc);
out = bc.buff;
return result;
}
uint64_t
Compressor::decompressToStream(const char*in, unsigned size, std::ostream& out){
// Set up the context and writer
WriterContext ctxt(&out,size / 2);
// Compress everything after the magic number (which we'll alter)
uint64_t zipSize = Compressor::decompress(in,size,
WriterContext::callback, (void*)&ctxt);
if (ctxt.chunk) {
ctxt.write(zipSize - ctxt.written);
}
return zipSize;
}
}
// vim: sw=2 ai