third_party/llvm-10.0/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFAArch64.h - SwiftShader - Git at Google

 //===-- RuntimeDyldCOFFAArch64.h --- COFF/AArch64 specific code ---*- 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
 //
 //===----------------------------------------------------------------------===//
 //
 // COFF AArch64 support for MC-JIT runtime dynamic linker.
 //
 //===----------------------------------------------------------------------===//

 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFFAARCH64_H
 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFFAARCH64_H

 #include "../RuntimeDyldCOFF.h"
 #include "llvm/BinaryFormat/COFF.h"
 #include "llvm/Object/COFF.h"
 #include "llvm/Support/Endian.h"

 #define DEBUG_TYPE "dyld"

 using namespace llvm::support::endian;

 namespace llvm {

 // This relocation type is used for handling long branch instruction
 // throught the Stub.
 enum InternalRelocationType : unsigned {
   INTERNAL_REL_ARM64_LONG_BRANCH26 = 0x111,
 };

 static void add16(uint8_t *p, int16_t v) { write16le(p, read16le(p) + v); }
 static void or32le(void *P, int32_t V) { write32le(P, read32le(P) | V); }

 static void write32AArch64Imm(uint8_t *T, uint64_t imm, uint32_t rangeLimit) {
   uint32_t orig = read32le(T);
   orig &= ~(0xFFF << 10);
   write32le(T, orig | ((imm & (0xFFF >> rangeLimit)) << 10));
 }

 static void write32AArch64Ldr(uint8_t *T, uint64_t imm) {
   uint32_t orig = read32le(T);
   uint32_t size = orig >> 30;
   // 0x04000000 indicates SIMD/FP registers
   // 0x00800000 indicates 128 bit
   if ((orig & 0x04800000) == 0x04800000)
     size += 4;
   if ((imm & ((1 << size) - 1)) != 0)
     assert(0 && "misaligned ldr/str offset");
   write32AArch64Imm(T, imm >> size, size);
 }

 static void write32AArch64Addr(void *T, uint64_t s, uint64_t p, int shift) {
   uint64_t Imm = (s >> shift) - (p >> shift);
   uint32_t ImmLo = (Imm & 0x3) << 29;
   uint32_t ImmHi = (Imm & 0x1FFFFC) << 3;
   uint64_t Mask = (0x3 << 29) | (0x1FFFFC << 3);
   write32le(T, (read32le(T) & ~Mask) | ImmLo | ImmHi);
 }

 class RuntimeDyldCOFFAArch64 : public RuntimeDyldCOFF {

 private:
   // When a module is loaded we save the SectionID of the unwind
   // sections in a table until we receive a request to register all
   // unregisteredEH frame sections with the memory manager.
   SmallVector<SID, 2> UnregisteredEHFrameSections;
   SmallVector<SID, 2> RegisteredEHFrameSections;
   uint64_t ImageBase;

   // Fake an __ImageBase pointer by returning the section with the lowest adress
   uint64_t getImageBase() {
     if (!ImageBase) {
       ImageBase = std::numeric_limits<uint64_t>::max();
       for (const SectionEntry &Section : Sections)
         // The Sections list may contain sections that weren't loaded for
         // whatever reason: they may be debug sections, and ProcessAllSections
         // is false, or they may be sections that contain 0 bytes. If the
         // section isn't loaded, the load address will be 0, and it should not
         // be included in the ImageBase calculation.
         if (Section.getLoadAddress() != 0)
           ImageBase = std::min(ImageBase, Section.getLoadAddress());
     }
     return ImageBase;
   }

 public:
   RuntimeDyldCOFFAArch64(RuntimeDyld::MemoryManager &MM,
                          JITSymbolResolver &Resolver)
       : RuntimeDyldCOFF(MM, Resolver), ImageBase(0) {}

   unsigned getStubAlignment() override { return 8; }

   unsigned getMaxStubSize() const override { return 20; }

   std::tuple<uint64_t, uint64_t, uint64_t>
   generateRelocationStub(unsigned SectionID, StringRef TargetName,
                          uint64_t Offset, uint64_t RelType, uint64_t Addend,
                          StubMap &Stubs) {
     uintptr_t StubOffset;
     SectionEntry &Section = Sections[SectionID];

     RelocationValueRef OriginalRelValueRef;
     OriginalRelValueRef.SectionID = SectionID;
     OriginalRelValueRef.Offset = Offset;
     OriginalRelValueRef.Addend = Addend;
     OriginalRelValueRef.SymbolName = TargetName.data();

     auto Stub = Stubs.find(OriginalRelValueRef);
     if (Stub == Stubs.end()) {
       LLVM_DEBUG(dbgs() << " Create a new stub function for "
                         << TargetName.data() << "\n");

       StubOffset = Section.getStubOffset();
       Stubs[OriginalRelValueRef] = StubOffset;
       createStubFunction(Section.getAddressWithOffset(StubOffset));
       Section.advanceStubOffset(getMaxStubSize());
     } else {
       LLVM_DEBUG(dbgs() << " Stub function found for " << TargetName.data()
                         << "\n");
       StubOffset = Stub->second;
     }

     // Resolve original relocation to stub function.
     const RelocationEntry RE(SectionID, Offset, RelType, Addend);
     resolveRelocation(RE, Section.getLoadAddressWithOffset(StubOffset));

     // adjust relocation info so resolution writes to the stub function
     // Here an internal relocation type is used for resolving long branch via
     // stub instruction.
     Addend = 0;
     Offset = StubOffset;
     RelType = INTERNAL_REL_ARM64_LONG_BRANCH26;

     return std::make_tuple(Offset, RelType, Addend);
   }

   Expected<object::relocation_iterator>
   processRelocationRef(unsigned SectionID, object::relocation_iterator RelI,
                        const object::ObjectFile &Obj,
                        ObjSectionToIDMap &ObjSectionToID,
                        StubMap &Stubs) override {

     auto Symbol = RelI->getSymbol();
     if (Symbol == Obj.symbol_end())
       report_fatal_error("Unknown symbol in relocation");

     Expected<StringRef> TargetNameOrErr = Symbol->getName();
     if (!TargetNameOrErr)
       return TargetNameOrErr.takeError();
     StringRef TargetName = *TargetNameOrErr;

     auto SectionOrErr = Symbol->getSection();
     if (!SectionOrErr)
       return SectionOrErr.takeError();
     auto Section = *SectionOrErr;

     uint64_t RelType = RelI->getType();
     uint64_t Offset = RelI->getOffset();

     // If there is no section, this must be an external reference.
     const bool IsExtern = Section == Obj.section_end();

     // Determine the Addend used to adjust the relocation value.
     uint64_t Addend = 0;
     SectionEntry &AddendSection = Sections[SectionID];
     uintptr_t ObjTarget = AddendSection.getObjAddress() + Offset;
     uint8_t *Displacement = (uint8_t *)ObjTarget;

     switch (RelType) {
     case COFF::IMAGE_REL_ARM64_ADDR32:
     case COFF::IMAGE_REL_ARM64_ADDR32NB:
     case COFF::IMAGE_REL_ARM64_REL32:
     case COFF::IMAGE_REL_ARM64_SECREL:
       Addend = read32le(Displacement);
       break;
     case COFF::IMAGE_REL_ARM64_BRANCH26: {
       uint32_t orig = read32le(Displacement);
       Addend = (orig & 0x03FFFFFF) << 2;

       if (IsExtern)
         std::tie(Offset, RelType, Addend) = generateRelocationStub(
             SectionID, TargetName, Offset, RelType, Addend, Stubs);
       break;
     }
     case COFF::IMAGE_REL_ARM64_BRANCH19: {
       uint32_t orig = read32le(Displacement);
       Addend = (orig & 0x00FFFFE0) >> 3;
       break;
     }
     case COFF::IMAGE_REL_ARM64_BRANCH14: {
       uint32_t orig = read32le(Displacement);
       Addend = (orig & 0x000FFFE0) >> 3;
       break;
     }
     case COFF::IMAGE_REL_ARM64_REL21:
     case COFF::IMAGE_REL_ARM64_PAGEBASE_REL21: {
       uint32_t orig = read32le(Displacement);
       Addend = ((orig >> 29) & 0x3) | ((orig >> 3) & 0x1FFFFC);
       break;
     }
     case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12L:
     case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12A: {
       uint32_t orig = read32le(Displacement);
       Addend = ((orig >> 10) & 0xFFF);
       break;
     }
     case COFF::IMAGE_REL_ARM64_ADDR64: {
       Addend = read64le(Displacement);
       break;
     }
     default:
       break;
     }

 #if !defined(NDEBUG)
     SmallString<32> RelTypeName;
     RelI->getTypeName(RelTypeName);

     LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
                       << " RelType: " << RelTypeName << " TargetName: "
                       << TargetName << " Addend " << Addend << "\n");
 #endif

     unsigned TargetSectionID = -1;
     if (IsExtern) {
       RelocationEntry RE(SectionID, Offset, RelType, Addend);
       addRelocationForSymbol(RE, TargetName);
     } else {
       if (auto TargetSectionIDOrErr = findOrEmitSection(
               Obj, *Section, Section->isText(), ObjSectionToID)) {
         TargetSectionID = *TargetSectionIDOrErr;
       } else
         return TargetSectionIDOrErr.takeError();

       uint64_t TargetOffset = getSymbolOffset(*Symbol);
       RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
       addRelocationForSection(RE, TargetSectionID);
     }
     return ++RelI;
   }

   void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
     const auto Section = Sections[RE.SectionID];
     uint8_t *Target = Section.getAddressWithOffset(RE.Offset);
     uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset);

     switch (RE.RelType) {
     default:
       llvm_unreachable("unsupported relocation type");
     case COFF::IMAGE_REL_ARM64_ABSOLUTE: {
       // This relocation is ignored.
       break;
     }
     case COFF::IMAGE_REL_ARM64_PAGEBASE_REL21: {
       // The page base of the target, for ADRP instruction.
       Value += RE.Addend;
       write32AArch64Addr(Target, Value, FinalAddress, 12);
       break;
     }
     case COFF::IMAGE_REL_ARM64_REL21: {
       // The 12-bit relative displacement to the target, for instruction ADR
       Value += RE.Addend;
       write32AArch64Addr(Target, Value, FinalAddress, 0);
       break;
     }
     case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12A: {
       // The 12-bit page offset of the target,
       // for instructions ADD/ADDS (immediate) with zero shift.
       Value += RE.Addend;
       write32AArch64Imm(Target, Value & 0xFFF, 0);
       break;
     }
     case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12L: {
       // The 12-bit page offset of the target,
       // for instruction LDR (indexed, unsigned immediate).
       Value += RE.Addend;
       write32AArch64Ldr(Target, Value & 0xFFF);
       break;
     }
     case COFF::IMAGE_REL_ARM64_ADDR32: {
       // The 32-bit VA of the target.
       uint32_t VA = Value + RE.Addend;
       write32le(Target, VA);
       break;
     }
     case COFF::IMAGE_REL_ARM64_ADDR32NB: {
       // The target's 32-bit RVA.
       uint64_t RVA = Value + RE.Addend - getImageBase();
       write32le(Target, RVA);
       break;
     }
     case INTERNAL_REL_ARM64_LONG_BRANCH26: {
       // Encode the immadiate value for generated Stub instruction (MOVZ)
       or32le(Target + 12, ((Value + RE.Addend) & 0xFFFF) << 5);
       or32le(Target + 8, ((Value + RE.Addend) & 0xFFFF0000) >> 11);
       or32le(Target + 4, ((Value + RE.Addend) & 0xFFFF00000000) >> 27);
       or32le(Target + 0, ((Value + RE.Addend) & 0xFFFF000000000000) >> 43);
       break;
     }
     case COFF::IMAGE_REL_ARM64_BRANCH26: {
       // The 26-bit relative displacement to the target, for B and BL
       // instructions.
       uint64_t PCRelVal = Value + RE.Addend - FinalAddress;
       assert(isInt<28>(PCRelVal) && "Branch target is out of range.");
       write32le(Target, (read32le(Target) & ~(0x03FFFFFF)) |
                             (PCRelVal & 0x0FFFFFFC) >> 2);
       break;
     }
     case COFF::IMAGE_REL_ARM64_BRANCH19: {
       // The 19-bit offset to the relocation target,
       // for conditional B instruction.
       uint64_t PCRelVal = Value + RE.Addend - FinalAddress;
       assert(isInt<21>(PCRelVal) && "Branch target is out of range.");
       write32le(Target, (read32le(Target) & ~(0x00FFFFE0)) |
                             (PCRelVal & 0x001FFFFC) << 3);
       break;
     }
     case COFF::IMAGE_REL_ARM64_BRANCH14: {
       // The 14-bit offset to the relocation target,
       // for instructions TBZ and TBNZ.
       uint64_t PCRelVal = Value + RE.Addend - FinalAddress;
       assert(isInt<16>(PCRelVal) && "Branch target is out of range.");
       write32le(Target, (read32le(Target) & ~(0x000FFFE0)) |
                             (PCRelVal & 0x0000FFFC) << 3);
       break;
     }
     case COFF::IMAGE_REL_ARM64_ADDR64: {
       // The 64-bit VA of the relocation target.
       write64le(Target, Value + RE.Addend);
       break;
     }
     case COFF::IMAGE_REL_ARM64_SECTION: {
       // 16-bit section index of the section that contains the target.
       assert(static_cast<uint32_t>(RE.SectionID) <= UINT16_MAX &&
              "relocation overflow");
       add16(Target, RE.SectionID);
       break;
     }
     case COFF::IMAGE_REL_ARM64_SECREL: {
       // 32-bit offset of the target from the beginning of its section.
       assert(static_cast<int64_t>(RE.Addend) <= INT32_MAX &&
              "Relocation overflow");
       assert(static_cast<int64_t>(RE.Addend) >= INT32_MIN &&
              "Relocation underflow");
       write32le(Target, RE.Addend);
       break;
     }
     case COFF::IMAGE_REL_ARM64_REL32: {
       // The 32-bit relative address from the byte following the relocation.
       uint64_t Result = Value - FinalAddress - 4;
       write32le(Target, Result + RE.Addend);
       break;
     }
     }
   }

   void registerEHFrames() override {}
 };

 } // End namespace llvm

 #endif
	//===-- RuntimeDyldCOFFAArch64.h --- COFF/AArch64 specific code ---*- 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
	//
	//===----------------------------------------------------------------------===//
	//
	// COFF AArch64 support for MC-JIT runtime dynamic linker.
	//
	//===----------------------------------------------------------------------===//

	#ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFFAARCH64_H
	#define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFFAARCH64_H

	#include "../RuntimeDyldCOFF.h"
	#include "llvm/BinaryFormat/COFF.h"
	#include "llvm/Object/COFF.h"
	#include "llvm/Support/Endian.h"

	#define DEBUG_TYPE "dyld"

	using namespace llvm::support::endian;

	namespace llvm {

	// This relocation type is used for handling long branch instruction
	// throught the Stub.
	enum InternalRelocationType : unsigned {
	INTERNAL_REL_ARM64_LONG_BRANCH26 = 0x111,
	};

	static void add16(uint8_t *p, int16_t v) { write16le(p, read16le(p) + v); }
	static void or32le(void *P, int32_t V) { write32le(P, read32le(P) \| V); }

	static void write32AArch64Imm(uint8_t *T, uint64_t imm, uint32_t rangeLimit) {
	uint32_t orig = read32le(T);
	orig &= ~(0xFFF << 10);
	write32le(T, orig \| ((imm & (0xFFF >> rangeLimit)) << 10));
	}

	static void write32AArch64Ldr(uint8_t *T, uint64_t imm) {
	uint32_t orig = read32le(T);
	uint32_t size = orig >> 30;
	// 0x04000000 indicates SIMD/FP registers
	// 0x00800000 indicates 128 bit
	if ((orig & 0x04800000) == 0x04800000)
	size += 4;
	if ((imm & ((1 << size) - 1)) != 0)
	assert(0 && "misaligned ldr/str offset");
	write32AArch64Imm(T, imm >> size, size);
	}

	static void write32AArch64Addr(void *T, uint64_t s, uint64_t p, int shift) {
	uint64_t Imm = (s >> shift) - (p >> shift);
	uint32_t ImmLo = (Imm & 0x3) << 29;
	uint32_t ImmHi = (Imm & 0x1FFFFC) << 3;
	uint64_t Mask = (0x3 << 29) \| (0x1FFFFC << 3);
	write32le(T, (read32le(T) & ~Mask) \| ImmLo \| ImmHi);
	}

	class RuntimeDyldCOFFAArch64 : public RuntimeDyldCOFF {

	private:
	// When a module is loaded we save the SectionID of the unwind
	// sections in a table until we receive a request to register all
	// unregisteredEH frame sections with the memory manager.
	SmallVector<SID, 2> UnregisteredEHFrameSections;
	SmallVector<SID, 2> RegisteredEHFrameSections;
	uint64_t ImageBase;

	// Fake an __ImageBase pointer by returning the section with the lowest adress
	uint64_t getImageBase() {
	if (!ImageBase) {
	ImageBase = std::numeric_limits<uint64_t>::max();
	for (const SectionEntry &Section : Sections)
	// The Sections list may contain sections that weren't loaded for
	// whatever reason: they may be debug sections, and ProcessAllSections
	// is false, or they may be sections that contain 0 bytes. If the
	// section isn't loaded, the load address will be 0, and it should not
	// be included in the ImageBase calculation.
	if (Section.getLoadAddress() != 0)
	ImageBase = std::min(ImageBase, Section.getLoadAddress());
	}
	return ImageBase;
	}

	public:
	RuntimeDyldCOFFAArch64(RuntimeDyld::MemoryManager &MM,
	JITSymbolResolver &Resolver)
	: RuntimeDyldCOFF(MM, Resolver), ImageBase(0) {}

	unsigned getStubAlignment() override { return 8; }

	unsigned getMaxStubSize() const override { return 20; }

	std::tuple<uint64_t, uint64_t, uint64_t>
	generateRelocationStub(unsigned SectionID, StringRef TargetName,
	uint64_t Offset, uint64_t RelType, uint64_t Addend,
	StubMap &Stubs) {
	uintptr_t StubOffset;
	SectionEntry &Section = Sections[SectionID];

	RelocationValueRef OriginalRelValueRef;
	OriginalRelValueRef.SectionID = SectionID;
	OriginalRelValueRef.Offset = Offset;
	OriginalRelValueRef.Addend = Addend;
	OriginalRelValueRef.SymbolName = TargetName.data();

	auto Stub = Stubs.find(OriginalRelValueRef);
	if (Stub == Stubs.end()) {
	LLVM_DEBUG(dbgs() << " Create a new stub function for "
	<< TargetName.data() << "\n");

	StubOffset = Section.getStubOffset();
	Stubs[OriginalRelValueRef] = StubOffset;
	createStubFunction(Section.getAddressWithOffset(StubOffset));
	Section.advanceStubOffset(getMaxStubSize());
	} else {
	LLVM_DEBUG(dbgs() << " Stub function found for " << TargetName.data()
	<< "\n");
	StubOffset = Stub->second;
	}

	// Resolve original relocation to stub function.
	const RelocationEntry RE(SectionID, Offset, RelType, Addend);
	resolveRelocation(RE, Section.getLoadAddressWithOffset(StubOffset));

	// adjust relocation info so resolution writes to the stub function
	// Here an internal relocation type is used for resolving long branch via
	// stub instruction.
	Addend = 0;
	Offset = StubOffset;
	RelType = INTERNAL_REL_ARM64_LONG_BRANCH26;

	return std::make_tuple(Offset, RelType, Addend);
	}

	Expected<object::relocation_iterator>
	processRelocationRef(unsigned SectionID, object::relocation_iterator RelI,
	const object::ObjectFile &Obj,
	ObjSectionToIDMap &ObjSectionToID,
	StubMap &Stubs) override {

	auto Symbol = RelI->getSymbol();
	if (Symbol == Obj.symbol_end())
	report_fatal_error("Unknown symbol in relocation");

	Expected<StringRef> TargetNameOrErr = Symbol->getName();
	if (!TargetNameOrErr)
	return TargetNameOrErr.takeError();
	StringRef TargetName = *TargetNameOrErr;

	auto SectionOrErr = Symbol->getSection();
	if (!SectionOrErr)
	return SectionOrErr.takeError();
	auto Section = *SectionOrErr;

	uint64_t RelType = RelI->getType();
	uint64_t Offset = RelI->getOffset();

	// If there is no section, this must be an external reference.
	const bool IsExtern = Section == Obj.section_end();

	// Determine the Addend used to adjust the relocation value.
	uint64_t Addend = 0;
	SectionEntry &AddendSection = Sections[SectionID];
	uintptr_t ObjTarget = AddendSection.getObjAddress() + Offset;
	uint8_t Displacement = (uint8_t )ObjTarget;

	switch (RelType) {
	case COFF::IMAGE_REL_ARM64_ADDR32:
	case COFF::IMAGE_REL_ARM64_ADDR32NB:
	case COFF::IMAGE_REL_ARM64_REL32:
	case COFF::IMAGE_REL_ARM64_SECREL:
	Addend = read32le(Displacement);
	break;
	case COFF::IMAGE_REL_ARM64_BRANCH26: {
	uint32_t orig = read32le(Displacement);
	Addend = (orig & 0x03FFFFFF) << 2;

	if (IsExtern)
	std::tie(Offset, RelType, Addend) = generateRelocationStub(
	SectionID, TargetName, Offset, RelType, Addend, Stubs);
	break;
	}
	case COFF::IMAGE_REL_ARM64_BRANCH19: {
	uint32_t orig = read32le(Displacement);
	Addend = (orig & 0x00FFFFE0) >> 3;
	break;
	}
	case COFF::IMAGE_REL_ARM64_BRANCH14: {
	uint32_t orig = read32le(Displacement);
	Addend = (orig & 0x000FFFE0) >> 3;
	break;
	}
	case COFF::IMAGE_REL_ARM64_REL21:
	case COFF::IMAGE_REL_ARM64_PAGEBASE_REL21: {
	uint32_t orig = read32le(Displacement);
	Addend = ((orig >> 29) & 0x3) \| ((orig >> 3) & 0x1FFFFC);
	break;
	}
	case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12L:
	case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12A: {
	uint32_t orig = read32le(Displacement);
	Addend = ((orig >> 10) & 0xFFF);
	break;
	}
	case COFF::IMAGE_REL_ARM64_ADDR64: {
	Addend = read64le(Displacement);
	break;
	}
	default:
	break;
	}

	#if !defined(NDEBUG)
	SmallString<32> RelTypeName;
	RelI->getTypeName(RelTypeName);

	LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
	<< " RelType: " << RelTypeName << " TargetName: "
	<< TargetName << " Addend " << Addend << "\n");
	#endif

	unsigned TargetSectionID = -1;
	if (IsExtern) {
	RelocationEntry RE(SectionID, Offset, RelType, Addend);
	addRelocationForSymbol(RE, TargetName);
	} else {
	if (auto TargetSectionIDOrErr = findOrEmitSection(
	Obj, *Section, Section->isText(), ObjSectionToID)) {
	TargetSectionID = *TargetSectionIDOrErr;
	} else
	return TargetSectionIDOrErr.takeError();

	uint64_t TargetOffset = getSymbolOffset(*Symbol);
	RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
	addRelocationForSection(RE, TargetSectionID);
	}
	return ++RelI;
	}

	void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
	const auto Section = Sections[RE.SectionID];
	uint8_t *Target = Section.getAddressWithOffset(RE.Offset);
	uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset);

	switch (RE.RelType) {
	default:
	llvm_unreachable("unsupported relocation type");
	case COFF::IMAGE_REL_ARM64_ABSOLUTE: {
	// This relocation is ignored.
	break;
	}
	case COFF::IMAGE_REL_ARM64_PAGEBASE_REL21: {
	// The page base of the target, for ADRP instruction.
	Value += RE.Addend;
	write32AArch64Addr(Target, Value, FinalAddress, 12);
	break;
	}
	case COFF::IMAGE_REL_ARM64_REL21: {
	// The 12-bit relative displacement to the target, for instruction ADR
	Value += RE.Addend;
	write32AArch64Addr(Target, Value, FinalAddress, 0);
	break;
	}
	case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12A: {
	// The 12-bit page offset of the target,
	// for instructions ADD/ADDS (immediate) with zero shift.
	Value += RE.Addend;
	write32AArch64Imm(Target, Value & 0xFFF, 0);
	break;
	}
	case COFF::IMAGE_REL_ARM64_PAGEOFFSET_12L: {
	// The 12-bit page offset of the target,
	// for instruction LDR (indexed, unsigned immediate).
	Value += RE.Addend;
	write32AArch64Ldr(Target, Value & 0xFFF);
	break;
	}
	case COFF::IMAGE_REL_ARM64_ADDR32: {
	// The 32-bit VA of the target.
	uint32_t VA = Value + RE.Addend;
	write32le(Target, VA);
	break;
	}
	case COFF::IMAGE_REL_ARM64_ADDR32NB: {
	// The target's 32-bit RVA.
	uint64_t RVA = Value + RE.Addend - getImageBase();
	write32le(Target, RVA);
	break;
	}
	case INTERNAL_REL_ARM64_LONG_BRANCH26: {
	// Encode the immadiate value for generated Stub instruction (MOVZ)
	or32le(Target + 12, ((Value + RE.Addend) & 0xFFFF) << 5);
	or32le(Target + 8, ((Value + RE.Addend) & 0xFFFF0000) >> 11);
	or32le(Target + 4, ((Value + RE.Addend) & 0xFFFF00000000) >> 27);
	or32le(Target + 0, ((Value + RE.Addend) & 0xFFFF000000000000) >> 43);
	break;
	}
	case COFF::IMAGE_REL_ARM64_BRANCH26: {
	// The 26-bit relative displacement to the target, for B and BL
	// instructions.
	uint64_t PCRelVal = Value + RE.Addend - FinalAddress;
	assert(isInt<28>(PCRelVal) && "Branch target is out of range.");
	write32le(Target, (read32le(Target) & ~(0x03FFFFFF)) \|
	(PCRelVal & 0x0FFFFFFC) >> 2);
	break;
	}
	case COFF::IMAGE_REL_ARM64_BRANCH19: {
	// The 19-bit offset to the relocation target,
	// for conditional B instruction.
	uint64_t PCRelVal = Value + RE.Addend - FinalAddress;
	assert(isInt<21>(PCRelVal) && "Branch target is out of range.");
	write32le(Target, (read32le(Target) & ~(0x00FFFFE0)) \|
	(PCRelVal & 0x001FFFFC) << 3);
	break;
	}
	case COFF::IMAGE_REL_ARM64_BRANCH14: {
	// The 14-bit offset to the relocation target,
	// for instructions TBZ and TBNZ.
	uint64_t PCRelVal = Value + RE.Addend - FinalAddress;
	assert(isInt<16>(PCRelVal) && "Branch target is out of range.");
	write32le(Target, (read32le(Target) & ~(0x000FFFE0)) \|
	(PCRelVal & 0x0000FFFC) << 3);
	break;
	}
	case COFF::IMAGE_REL_ARM64_ADDR64: {
	// The 64-bit VA of the relocation target.
	write64le(Target, Value + RE.Addend);
	break;
	}
	case COFF::IMAGE_REL_ARM64_SECTION: {
	// 16-bit section index of the section that contains the target.
	assert(static_cast<uint32_t>(RE.SectionID) <= UINT16_MAX &&
	"relocation overflow");
	add16(Target, RE.SectionID);
	break;
	}
	case COFF::IMAGE_REL_ARM64_SECREL: {
	// 32-bit offset of the target from the beginning of its section.
	assert(static_cast<int64_t>(RE.Addend) <= INT32_MAX &&
	"Relocation overflow");
	assert(static_cast<int64_t>(RE.Addend) >= INT32_MIN &&
	"Relocation underflow");
	write32le(Target, RE.Addend);
	break;
	}
	case COFF::IMAGE_REL_ARM64_REL32: {
	// The 32-bit relative address from the byte following the relocation.
	uint64_t Result = Value - FinalAddress - 4;
	write32le(Target, Result + RE.Addend);
	break;
	}
	}
	}

	void registerEHFrames() override {}
	};

	} // End namespace llvm

	#endif