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llvm-mirror/include/llvm/MC/MCWasmObjectWriter.h
Derek Schuff 0c7127a873 [WebAssembly] Generate R_WASM_FUNCTION_OFFSET relocs in debuginfo sections
Debug info sections need R_WASM_FUNCTION_OFFSET_I32 relocs (with FK_Data_4 fixup
kinds) to refer to functions (instead of R_WASM_TABLE_INDEX as is used in data
sections). Usually this is done in a convoluted way, with unnamed temp data
symbols which target the start of the function, in which case
WasmObjectWriter::recordRelocation converts it to use the section symbol
instead. However in some cases the function can actually be undefined; in this
case the dwarf generator uses the function symbol (a named undefined function
symbol) instead. In that case the section-symbol transform doesn't work and we
need to generate the correct reloc type a different way. In this change
WebAssemblyWasmObjectWriter::getRelocType takes the fixup section type into
account to choose the correct reloc type.

Fixes PR50408
Differential Revision: https://reviews.llvm.org/D103557
2021-07-19 14:02:33 -07:00

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1.9 KiB
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//===-- 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 MCSectionWasm;
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,
const MCSectionWasm &FixupSection,
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