llvm-6502/include/llvm/Support/MemoryBuffer.h
Benjamin Kramer d4d1f85aa7 Tweak MemoryBuffer to allocate the class itself, the name and possibly the
buffer in the same chunk of memory.

2 less mallocs for every uninitialized MemoryBuffer and 1 less malloc for every
MemoryBuffer pointing to a memory range translate into 20% less mallocs on
clang -cc1 -Eonly Cocoa_h.m.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106839 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-25 11:50:40 +00:00

118 lines
5.0 KiB
C++

//===--- MemoryBuffer.h - Memory Buffer Interface ---------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the MemoryBuffer interface.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_MEMORYBUFFER_H
#define LLVM_SUPPORT_MEMORYBUFFER_H
#include "llvm/ADT/StringRef.h"
#include "llvm/System/DataTypes.h"
#include <string>
#include <sys/stat.h>
namespace llvm {
/// MemoryBuffer - This interface provides simple read-only access to a block
/// of memory, and provides simple methods for reading files and standard input
/// into a memory buffer. In addition to basic access to the characters in the
/// file, this interface guarantees you can read one character past the end of
/// the file, and that this character will read as '\0'.
///
/// The '\0' guarantee is needed to support an optimization -- it's intended to
/// be more efficient for clients which are reading all the data to stop
/// reading when they encounter a '\0' than to continually check the file
/// position to see if it has reached the end of the file.
class MemoryBuffer {
const char *BufferStart; // Start of the buffer.
const char *BufferEnd; // End of the buffer.
MemoryBuffer(const MemoryBuffer &); // DO NOT IMPLEMENT
MemoryBuffer &operator=(const MemoryBuffer &); // DO NOT IMPLEMENT
protected:
MemoryBuffer() {}
void init(const char *BufStart, const char *BufEnd);
public:
virtual ~MemoryBuffer();
const char *getBufferStart() const { return BufferStart; }
const char *getBufferEnd() const { return BufferEnd; }
size_t getBufferSize() const { return BufferEnd-BufferStart; }
StringRef getBuffer() const {
return StringRef(BufferStart, getBufferSize());
}
/// getBufferIdentifier - Return an identifier for this buffer, typically the
/// filename it was read from.
virtual const char *getBufferIdentifier() const {
return "Unknown buffer";
}
/// getFile - Open the specified file as a MemoryBuffer, returning a new
/// MemoryBuffer if successful, otherwise returning null. If FileSize is
/// specified, this means that the client knows that the file exists and that
/// it has the specified size.
static MemoryBuffer *getFile(StringRef Filename,
std::string *ErrStr = 0,
int64_t FileSize = -1,
struct stat *FileInfo = 0);
static MemoryBuffer *getFile(const char *Filename,
std::string *ErrStr = 0,
int64_t FileSize = -1,
struct stat *FileInfo = 0);
/// getMemBuffer - Open the specified memory range as a MemoryBuffer. Note
/// that EndPtr[0] must be a null byte and be accessible!
static MemoryBuffer *getMemBuffer(StringRef InputData,
StringRef BufferName = "");
/// getMemBufferCopy - Open the specified memory range as a MemoryBuffer,
/// copying the contents and taking ownership of it. This has no requirements
/// on EndPtr[0].
static MemoryBuffer *getMemBufferCopy(StringRef InputData,
StringRef BufferName = "");
/// getNewMemBuffer - Allocate a new MemoryBuffer of the specified size that
/// is completely initialized to zeros. Note that the caller should
/// initialize the memory allocated by this method. The memory is owned by
/// the MemoryBuffer object.
static MemoryBuffer *getNewMemBuffer(size_t Size, StringRef BufferName = "");
/// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
/// that is not initialized. Note that the caller should initialize the
/// memory allocated by this method. The memory is owned by the MemoryBuffer
/// object.
static MemoryBuffer *getNewUninitMemBuffer(size_t Size,
StringRef BufferName = "");
/// getSTDIN - Read all of stdin into a file buffer, and return it.
/// If an error occurs, this returns null and fills in *ErrStr with a reason.
static MemoryBuffer *getSTDIN(std::string *ErrStr = 0);
/// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
/// if the Filename is "-". If an error occurs, this returns null and fills
/// in *ErrStr with a reason.
static MemoryBuffer *getFileOrSTDIN(StringRef Filename,
std::string *ErrStr = 0,
int64_t FileSize = -1,
struct stat *FileInfo = 0);
static MemoryBuffer *getFileOrSTDIN(const char *Filename,
std::string *ErrStr = 0,
int64_t FileSize = -1,
struct stat *FileInfo = 0);
};
} // end namespace llvm
#endif