From 61aaf2e0afe8b119094faf67912f0446a7c7d71e Mon Sep 17 00:00:00 2001
From: Reid Spencer <rspencer@reidspencer.com>
Date: Sun, 14 Nov 2004 21:59:21 +0000
Subject: [PATCH] Simplify decompression code by using the high level interface
to the Compressor
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17768 91177308-0d34-0410-b5e6-96231b3b80d8
---
lib/Bytecode/Reader/Reader.cpp | 68 ++++++----------------------------
1 file changed, 11 insertions(+), 57 deletions(-)
diff --git a/lib/Bytecode/Reader/Reader.cpp b/lib/Bytecode/Reader/Reader.cpp
index 0984e8e0736..e83228d74a5 100644
--- a/lib/Bytecode/Reader/Reader.cpp
+++ b/lib/Bytecode/Reader/Reader.cpp
@@ -2157,43 +2157,6 @@ void BytecodeReader::ParseModule() {
error("Function declared, but bytecode stream ended before definition");
}
-/// 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 GetDecompressionBuffer(char*&buff, unsigned& sz, void* ctxt){
- // Case the context variable to our BufferInfo
- BytecodeReader::BufferInfo* bi =
- reinterpret_cast<BytecodeReader::BufferInfo*>(ctxt);
-
- // Compute the new, doubled, size of the block
- unsigned new_size = bi->size * 2;
-
- // Extend or allocate the block (realloc(0,n) == malloc(n))
- char* new_buff = (char*) ::realloc(bi->buff, new_size);
-
- // Figure out what to return to the Compressor. If this is the first call,
- // then bi->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 BufferInfo.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 (bi->buff == 0 ) {
- buff = bi->buff = new_buff;
- sz = new_size;
- } else {
- bi->buff = new_buff;
- buff = new_buff + bi->size;
- sz = bi->size;
- }
-
- // Retain the size of the allocated block
- bi->size = new_size;
-
- // Make sure we fail (return 1) if we didn't get any memory.
- return (bi->buff == 0 ? 1 : 0);
-}
-
/// This function completely parses a bytecode buffer given by the \p Buf
/// and \p Length parameters.
void BytecodeReader::ParseBytecode(BufPtr Buf, unsigned Length,
@@ -2214,27 +2177,18 @@ void BytecodeReader::ParseBytecode(BufPtr Buf, unsigned Length,
// If this is a compressed file
if (Sig == ('l' | ('l' << 8) | ('v' << 16) | ('c' << 24))) {
- // 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 GetDecompressionBuffer for an initial allocation of 4xLength. 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.
- bi.size = Length * 2;
-
// Invoke the decompression of the bytecode. Note that we have to skip the
// file's magic number which is not part of the compressed block. Hence,
- // the Buf+4 and Length-4.
- unsigned decompressedLength = Compressor::decompress((char*)Buf+4,Length-4,
- GetDecompressionBuffer, (void*) &bi);
+ // the Buf+4 and Length-4. The result goes into decompressedBlock, a data
+ // member for retention until BytecodeReader is destructed.
+ unsigned decompressedLength = Compressor::decompressToNewBuffer(
+ (char*)Buf+4,Length-4,decompressedBlock);
// We must adjust the buffer pointers used by the bytecode reader to point
- // into the new decompressed block. After decompression, the BufferInfo
- // structure (member bi), will point to a contiguous memory area that has
+ // into the new decompressed block. After decompression, the
+ // decompressedBlock will point to a contiguous memory area that has
// the decompressed data.
- At = MemStart = BlockStart = Buf = (BufPtr) bi.buff;
+ At = MemStart = BlockStart = Buf = (BufPtr) decompressedBlock;
MemEnd = BlockEnd = Buf + decompressedLength;
// else if this isn't a regular (uncompressed) bytecode file, then its
@@ -2286,8 +2240,8 @@ void BytecodeReader::ParseBytecode(BufPtr Buf, unsigned Length,
freeState();
delete TheModule;
TheModule = 0;
- if (bi.buff != 0 )
- ::free(bi.buff);
+ if (decompressedBlock != 0 )
+ ::free(decompressedBlock);
throw;
} catch (...) {
std::string msg("Unknown Exception Occurred");
@@ -2295,8 +2249,8 @@ void BytecodeReader::ParseBytecode(BufPtr Buf, unsigned Length,
freeState();
delete TheModule;
TheModule = 0;
- if (bi.buff != 0 )
- ::free(bi.buff);
+ if (decompressedBlock != 0 )
+ ::free(decompressedBlock);
throw msg;
}
}