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