mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-11-22 18:54:02 +01:00
c75c8e75b3
During D88827 it was requested to remove the local implementation
of Memory/File Buffers:
// TODO: refactor the buffer classes in LLVM to enable us to use them here
// directly.
This patch uses raw_ostream instead of Buffers. Generally, using streams
could allow us to reduce memory usages. No need to load all data into the
memory - the data could be streamed through a smaller buffer.
Thus, this patch uses raw_ostream as an interface for output data:
Error executeObjcopyOnBinary(CopyConfig &Config,
object::Binary &In,
raw_ostream &Out);
Note 1. This patch does not change the implementation of Writers
so that data would be directly stored into raw_ostream.
This is assumed to be done later.
Note 2. It would be better if Writers would be implemented in a such way
that data could be streamed without seeking/updating. If that would be
inconvenient then raw_ostream could be replaced with raw_pwrite_stream
to have a possibility to seek back and update file headers.
This is assumed to be done later if necessary.
Note 3. Current FileOutputBuffer allows using a memory-mapped file.
The raw_fd_ostream (which could be used if data should be stored in the file)
does not allow us to use a memory-mapped file. Memory map functionality
could be implemented for raw_fd_ostream:
It is possible to add resize() method into raw_ostream.
class raw_ostream {
void resize(uint64_t size);
}
That method, implemented for raw_fd_ostream, could create a memory-mapped file.
The streamed data would be written into that memory file then.
Thus we would be able to use memory-mapped files with raw_fd_ostream.
This is assumed to be done later if necessary.
Differential Revision: https://reviews.llvm.org/D91028
50 lines
1.6 KiB
C++
50 lines
1.6 KiB
C++
//===- Writer.h -------------------------------------------------*- C++ -*-===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_TOOLS_LLVM_OBJCOPY_WASM_WRITER_H
|
|
#define LLVM_TOOLS_LLVM_OBJCOPY_WASM_WRITER_H
|
|
|
|
#include "Object.h"
|
|
#include <cstdint>
|
|
#include <vector>
|
|
|
|
namespace llvm {
|
|
namespace objcopy {
|
|
namespace wasm {
|
|
|
|
class Writer {
|
|
public:
|
|
Writer(Object &Obj, raw_ostream &Out) : Obj(Obj), Out(Out) {}
|
|
Error write();
|
|
|
|
private:
|
|
using SectionHeader = SmallVector<char, 8>;
|
|
Object &Obj;
|
|
raw_ostream &Out;
|
|
std::vector<SectionHeader> SectionHeaders;
|
|
|
|
/// Generate a wasm section section header for S.
|
|
/// The header consists of
|
|
/// * A one-byte section ID (aka the section type).
|
|
/// * The size of the section contents, encoded as ULEB128.
|
|
/// * If the section is a custom section (type 0) it also has a name, which is
|
|
/// encoded as a length-prefixed string. The encoded section size *includes*
|
|
/// this string.
|
|
/// See https://webassembly.github.io/spec/core/binary/modules.html#sections
|
|
/// Return the header and store the total size in SectionSize.
|
|
static SectionHeader createSectionHeader(const Section &S,
|
|
size_t &SectionSize);
|
|
size_t finalize();
|
|
};
|
|
|
|
} // end namespace wasm
|
|
} // end namespace objcopy
|
|
} // end namespace llvm
|
|
|
|
#endif // LLVM_TOOLS_LLVM_OBJCOPY_WASM_WRITER_H
|