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//===-- WebAssemblyELFObjectWriter.cpp - WebAssembly ELF Writer -----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief This file handles ELF-specific object emission, converting LLVM's
/// internal fixups into the appropriate relocations.
///
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "llvm/MC/MCELFObjectWriter.h"
#include "llvm/MC/MCFixup.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
namespace {
class WebAssemblyELFObjectWriter final : public MCELFObjectTargetWriter {
public:
WebAssemblyELFObjectWriter(bool Is64Bit, uint8_t OSABI);
protected:
unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
const MCFixup &Fixup, bool IsPCRel) const override;
};
} // end anonymous namespace
WebAssemblyELFObjectWriter::WebAssemblyELFObjectWriter(bool Is64Bit,
uint8_t OSABI)
: MCELFObjectTargetWriter(Is64Bit, OSABI, ELF::EM_WEBASSEMBLY,
/*HasRelocationAddend=*/false) {}
unsigned WebAssemblyELFObjectWriter::getRelocType(MCContext &Ctx,
const MCValue &Target,
const MCFixup &Fixup,
bool IsPCRel) const {
// WebAssembly functions are not allocated in the address space. To resolve a
// pointer to a function, we must use a special relocation type.
if (const MCSymbolRefExpr *SyExp =
dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
if (SyExp->getKind() == MCSymbolRefExpr::VK_WebAssembly_FUNCTION)
return ELF::R_WEBASSEMBLY_FUNCTION;
switch (Fixup.getKind()) {
case FK_Data_4:
assert(!is64Bit() && "4-byte relocations only supported on wasm32");
return ELF::R_WEBASSEMBLY_DATA;
case FK_Data_8:
assert(is64Bit() && "8-byte relocations only supported on wasm64");
return ELF::R_WEBASSEMBLY_DATA;
default:
llvm_unreachable("unimplemented fixup kind");
}
}
MCObjectWriter *llvm::createWebAssemblyELFObjectWriter(raw_pwrite_stream &OS,
bool Is64Bit,
uint8_t OSABI) {
MCELFObjectTargetWriter *MOTW =
new WebAssemblyELFObjectWriter(Is64Bit, OSABI);
return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/true);
}
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