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llvm-mirror/include/llvm/MC/MCWasmObjectWriter.h
Yuta Saito 9526edaf68 [WebAssembly] Add new relocation for location relative data
This `R_WASM_MEMORY_ADDR_SELFREL_I32` relocation represents an offset
between its relocating address and the symbol address. It's very similar
to `R_X86_64_PC32` but restricted to be used for only data segments.

```
S + A - P
```

A: Represents the addend used to compute the value of the relocatable
field.
P: Represents the place of the storage unit being relocated.
S: Represents the value of the symbol whose index resides in the
relocation entry.

Proposal: https://github.com/WebAssembly/tool-conventions/issues/162

Differential Revision: https://reviews.llvm.org/D96659
2021-03-08 11:34:10 -08:00

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1.8 KiB
C++

//===-- llvm/MC/MCWasmObjectWriter.h - Wasm Object Writer -------*- 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_MC_MCWASMOBJECTWRITER_H
#define LLVM_MC_MCWASMOBJECTWRITER_H
#include "llvm/MC/MCObjectWriter.h"
#include <memory>
namespace llvm {
class MCFixup;
class MCValue;
class raw_pwrite_stream;
class MCWasmObjectTargetWriter : public MCObjectTargetWriter {
const unsigned Is64Bit : 1;
const unsigned IsEmscripten : 1;
protected:
explicit MCWasmObjectTargetWriter(bool Is64Bit_, bool IsEmscripten);
public:
virtual ~MCWasmObjectTargetWriter();
Triple::ObjectFormatType getFormat() const override { return Triple::Wasm; }
static bool classof(const MCObjectTargetWriter *W) {
return W->getFormat() == Triple::Wasm;
}
virtual unsigned getRelocType(const MCValue &Target, const MCFixup &Fixup,
bool IsLocRel) const = 0;
/// \name Accessors
/// @{
bool is64Bit() const { return Is64Bit; }
bool isEmscripten() const { return IsEmscripten; }
/// @}
};
/// Construct a new Wasm writer instance.
///
/// \param MOTW - The target specific Wasm writer subclass.
/// \param OS - The stream to write to.
/// \returns The constructed object writer.
std::unique_ptr<MCObjectWriter>
createWasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
raw_pwrite_stream &OS);
std::unique_ptr<MCObjectWriter>
createWasmDwoObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
raw_pwrite_stream &OS, raw_pwrite_stream &DwoOS);
} // namespace llvm
#endif