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arudradey/ml-cpu-storage / emsdk /upstream /emscripten /system /lib /libunwind /src /UnwindCursor.hpp

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	//===----------------------------------------------------------------------===//
	//
	// 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
	//
	//
	// C++ interface to lower levels of libunwind
	//===----------------------------------------------------------------------===//

	#ifndef __UNWINDCURSOR_HPP__
	#define __UNWINDCURSOR_HPP__

	#include "shadow_stack_unwind.h"
	#include <stdint.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <unwind.h>

	#ifdef _WIN32
	#include <windows.h>
	#include <ntverp.h>
	#endif
	#ifdef __APPLE__
	#include <mach-o/dyld.h>
	#endif
	#ifdef _AIX
	#include <dlfcn.h>
	#include <sys/debug.h>
	#include <sys/pseg.h>
	#endif

	#if defined(_LIBUNWIND_TARGET_LINUX) && \
	(defined(_LIBUNWIND_TARGET_AARCH64) \|\| \
	defined(_LIBUNWIND_TARGET_LOONGARCH) \|\| \
	defined(_LIBUNWIND_TARGET_RISCV) \|\| defined(_LIBUNWIND_TARGET_S390X))
	#include <errno.h>
	#include <signal.h>
	#include <sys/syscall.h>
	#include <unistd.h>
	#define _LIBUNWIND_CHECK_LINUX_SIGRETURN 1
	#endif

	#if defined(_LIBUNWIND_TARGET_HAIKU) && defined(_LIBUNWIND_TARGET_X86_64)
	#include <OS.h>
	#include <signal.h>
	#define _LIBUNWIND_CHECK_HAIKU_SIGRETURN 1
	#endif

	#include "AddressSpace.hpp"
	#include "CompactUnwinder.hpp"
	#include "config.h"
	#include "DwarfInstructions.hpp"
	#include "EHHeaderParser.hpp"
	#include "libunwind.h"
	#include "libunwind_ext.h"
	#include "Registers.hpp"
	#include "RWMutex.hpp"
	#include "Unwind-EHABI.h"

	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
	// Provide a definition for the DISPATCHER_CONTEXT struct for old (Win7 and
	// earlier) SDKs.
	// MinGW-w64 has always provided this struct.
	#if defined(_WIN32) && defined(_LIBUNWIND_TARGET_X86_64) && \
	!defined(__MINGW32__) && VER_PRODUCTBUILD < 8000
	struct _DISPATCHER_CONTEXT {
	ULONG64 ControlPc;
	ULONG64 ImageBase;
	PRUNTIME_FUNCTION FunctionEntry;
	ULONG64 EstablisherFrame;
	ULONG64 TargetIp;
	PCONTEXT ContextRecord;
	PEXCEPTION_ROUTINE LanguageHandler;
	PVOID HandlerData;
	PUNWIND_HISTORY_TABLE HistoryTable;
	ULONG ScopeIndex;
	ULONG Fill0;
	};
	#endif

	struct UNWIND_INFO {
	uint8_t Version : 3;
	uint8_t Flags : 5;
	uint8_t SizeOfProlog;
	uint8_t CountOfCodes;
	uint8_t FrameRegister : 4;
	uint8_t FrameOffset : 4;
	uint16_t UnwindCodes[2];
	};

	#pragma clang diagnostic push
	#pragma clang diagnostic ignored "-Wgnu-anonymous-struct"
	union UNWIND_INFO_ARM {
	DWORD HeaderData;
	struct {
	DWORD FunctionLength : 18;
	DWORD Version : 2;
	DWORD ExceptionDataPresent : 1;
	DWORD EpilogInHeader : 1;
	DWORD FunctionFragment : 1;
	DWORD EpilogCount : 5;
	DWORD CodeWords : 4;
	};
	};
	#pragma clang diagnostic pop

	extern "C" _Unwind_Reason_Code __libunwind_seh_personality(
	int, _Unwind_Action, uint64_t, _Unwind_Exception *,
	struct _Unwind_Context *);

	#endif

	namespace libunwind {

	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
	/// Cache of recently found FDEs.
	template <typename A>
	class _LIBUNWIND_HIDDEN DwarfFDECache {
	typedef typename A::pint_t pint_t;
	public:
	static constexpr pint_t kSearchAll = static_cast<pint_t>(-1);
	static pint_t findFDE(pint_t mh, pint_t pc);
	static void add(pint_t mh, pint_t ip_start, pint_t ip_end, pint_t fde);
	static void removeAllIn(pint_t mh);
	static void iterateCacheEntries(void (*func)(unw_word_t ip_start,
	unw_word_t ip_end,
	unw_word_t fde, unw_word_t mh));

	private:

	struct entry {
	pint_t mh;
	pint_t ip_start;
	pint_t ip_end;
	pint_t fde;
	};

	// These fields are all static to avoid needing an initializer.
	// There is only one instance of this class per process.
	static RWMutex _lock;
	#ifdef __APPLE__
	static void dyldUnloadHook(const struct mach_header *mh, intptr_t slide);
	static bool _registeredForDyldUnloads;
	#endif
	static entry *_buffer;
	static entry *_bufferUsed;
	static entry *_bufferEnd;
	static entry _initialBuffer[64];
	};

	template <typename A>
	typename DwarfFDECache<A>::entry *
	DwarfFDECache<A>::_buffer = _initialBuffer;

	template <typename A>
	typename DwarfFDECache<A>::entry *
	DwarfFDECache<A>::_bufferUsed = _initialBuffer;

	template <typename A>
	typename DwarfFDECache<A>::entry *
	DwarfFDECache<A>::_bufferEnd = &_initialBuffer[64];

	template <typename A>
	typename DwarfFDECache<A>::entry DwarfFDECache<A>::_initialBuffer[64];

	template <typename A>
	RWMutex DwarfFDECache<A>::_lock;

	#ifdef __APPLE__
	template <typename A>
	bool DwarfFDECache<A>::_registeredForDyldUnloads = false;
	#endif

	template <typename A>
	typename DwarfFDECache<A>::pint_t DwarfFDECache<A>::findFDE(pint_t mh,
	pint_t pc) {
	pint_t result = 0;
	_LIBUNWIND_LOG_IF_FALSE(_lock.lock_shared());
	for (entry *p = _buffer; p < _bufferUsed; ++p) {
	if ((mh == p->mh) \|\| (mh == kSearchAll)) {
	if ((p->ip_start <= pc) && (pc < p->ip_end)) {
	result = p->fde;
	break;
	}
	}
	}
	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock_shared());
	return result;
	}

	template <typename A>
	void DwarfFDECache<A>::add(pint_t mh, pint_t ip_start, pint_t ip_end,
	pint_t fde) {
	#if !defined(_LIBUNWIND_NO_HEAP)
	_LIBUNWIND_LOG_IF_FALSE(_lock.lock());
	if (_bufferUsed >= _bufferEnd) {
	size_t oldSize = (size_t)(_bufferEnd - _buffer);
	size_t newSize = oldSize * 4;
	// Can't use operator new (we are below it).
	entry newBuffer = (entry )malloc(newSize * sizeof(entry));
	memcpy(newBuffer, _buffer, oldSize * sizeof(entry));
	if (_buffer != _initialBuffer)
	free(_buffer);
	_buffer = newBuffer;
	_bufferUsed = &newBuffer[oldSize];
	_bufferEnd = &newBuffer[newSize];
	}
	_bufferUsed->mh = mh;
	_bufferUsed->ip_start = ip_start;
	_bufferUsed->ip_end = ip_end;
	_bufferUsed->fde = fde;
	++_bufferUsed;
	#ifdef __APPLE__
	if (!_registeredForDyldUnloads) {
	_dyld_register_func_for_remove_image(&dyldUnloadHook);
	_registeredForDyldUnloads = true;
	}
	#endif
	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
	#endif
	}

	template <typename A>
	void DwarfFDECache<A>::removeAllIn(pint_t mh) {
	_LIBUNWIND_LOG_IF_FALSE(_lock.lock());
	entry *d = _buffer;
	for (const entry *s = _buffer; s < _bufferUsed; ++s) {
	if (s->mh != mh) {
	if (d != s)
	d = s;
	++d;
	}
	}
	_bufferUsed = d;
	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
	}

	#ifdef __APPLE__
	template <typename A>
	void DwarfFDECache<A>::dyldUnloadHook(const struct mach_header *mh, intptr_t ) {
	removeAllIn((pint_t) mh);
	}
	#endif

	template <typename A>
	void DwarfFDECache<A>::iterateCacheEntries(void (*func)(
	unw_word_t ip_start, unw_word_t ip_end, unw_word_t fde, unw_word_t mh)) {
	_LIBUNWIND_LOG_IF_FALSE(_lock.lock());
	for (entry *p = _buffer; p < _bufferUsed; ++p) {
	(*func)(p->ip_start, p->ip_end, p->fde, p->mh);
	}
	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
	}
	#endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)

	#define arrayoffsetof(type, index, field) \
	(sizeof(type) * (index) + offsetof(type, field))

	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
	template <typename A> class UnwindSectionHeader {
	public:
	UnwindSectionHeader(A &addressSpace, typename A::pint_t addr)
	: _addressSpace(addressSpace), _addr(addr) {}

	uint32_t version() const {
	return _addressSpace.get32(_addr +
	offsetof(unwind_info_section_header, version));
	}
	uint32_t commonEncodingsArraySectionOffset() const {
	return _addressSpace.get32(_addr +
	offsetof(unwind_info_section_header,
	commonEncodingsArraySectionOffset));
	}
	uint32_t commonEncodingsArrayCount() const {
	return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
	commonEncodingsArrayCount));
	}
	uint32_t personalityArraySectionOffset() const {
	return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
	personalityArraySectionOffset));
	}
	uint32_t personalityArrayCount() const {
	return _addressSpace.get32(
	_addr + offsetof(unwind_info_section_header, personalityArrayCount));
	}
	uint32_t indexSectionOffset() const {
	return _addressSpace.get32(
	_addr + offsetof(unwind_info_section_header, indexSectionOffset));
	}
	uint32_t indexCount() const {
	return _addressSpace.get32(
	_addr + offsetof(unwind_info_section_header, indexCount));
	}

	private:
	A &_addressSpace;
	typename A::pint_t _addr;
	};

	template <typename A> class UnwindSectionIndexArray {
	public:
	UnwindSectionIndexArray(A &addressSpace, typename A::pint_t addr)
	: _addressSpace(addressSpace), _addr(addr) {}

	uint32_t functionOffset(uint32_t index) const {
	return _addressSpace.get32(
	_addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
	functionOffset));
	}
	uint32_t secondLevelPagesSectionOffset(uint32_t index) const {
	return _addressSpace.get32(
	_addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
	secondLevelPagesSectionOffset));
	}
	uint32_t lsdaIndexArraySectionOffset(uint32_t index) const {
	return _addressSpace.get32(
	_addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
	lsdaIndexArraySectionOffset));
	}

	private:
	A &_addressSpace;
	typename A::pint_t _addr;
	};

	template <typename A> class UnwindSectionRegularPageHeader {
	public:
	UnwindSectionRegularPageHeader(A &addressSpace, typename A::pint_t addr)
	: _addressSpace(addressSpace), _addr(addr) {}

	uint32_t kind() const {
	return _addressSpace.get32(
	_addr + offsetof(unwind_info_regular_second_level_page_header, kind));
	}
	uint16_t entryPageOffset() const {
	return _addressSpace.get16(
	_addr + offsetof(unwind_info_regular_second_level_page_header,
	entryPageOffset));
	}
	uint16_t entryCount() const {
	return _addressSpace.get16(
	_addr +
	offsetof(unwind_info_regular_second_level_page_header, entryCount));
	}

	private:
	A &_addressSpace;
	typename A::pint_t _addr;
	};

	template <typename A> class UnwindSectionRegularArray {
	public:
	UnwindSectionRegularArray(A &addressSpace, typename A::pint_t addr)
	: _addressSpace(addressSpace), _addr(addr) {}

	uint32_t functionOffset(uint32_t index) const {
	return _addressSpace.get32(
	_addr + arrayoffsetof(unwind_info_regular_second_level_entry, index,
	functionOffset));
	}
	uint32_t encoding(uint32_t index) const {
	return _addressSpace.get32(
	_addr +
	arrayoffsetof(unwind_info_regular_second_level_entry, index, encoding));
	}

	private:
	A &_addressSpace;
	typename A::pint_t _addr;
	};

	template <typename A> class UnwindSectionCompressedPageHeader {
	public:
	UnwindSectionCompressedPageHeader(A &addressSpace, typename A::pint_t addr)
	: _addressSpace(addressSpace), _addr(addr) {}

	uint32_t kind() const {
	return _addressSpace.get32(
	_addr +
	offsetof(unwind_info_compressed_second_level_page_header, kind));
	}
	uint16_t entryPageOffset() const {
	return _addressSpace.get16(
	_addr + offsetof(unwind_info_compressed_second_level_page_header,
	entryPageOffset));
	}
	uint16_t entryCount() const {
	return _addressSpace.get16(
	_addr +
	offsetof(unwind_info_compressed_second_level_page_header, entryCount));
	}
	uint16_t encodingsPageOffset() const {
	return _addressSpace.get16(
	_addr + offsetof(unwind_info_compressed_second_level_page_header,
	encodingsPageOffset));
	}
	uint16_t encodingsCount() const {
	return _addressSpace.get16(
	_addr + offsetof(unwind_info_compressed_second_level_page_header,
	encodingsCount));
	}

	private:
	A &_addressSpace;
	typename A::pint_t _addr;
	};

	template <typename A> class UnwindSectionCompressedArray {
	public:
	UnwindSectionCompressedArray(A &addressSpace, typename A::pint_t addr)
	: _addressSpace(addressSpace), _addr(addr) {}

	uint32_t functionOffset(uint32_t index) const {
	return UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(
	_addressSpace.get32(_addr + index * sizeof(uint32_t)));
	}
	uint16_t encodingIndex(uint32_t index) const {
	return UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(
	_addressSpace.get32(_addr + index * sizeof(uint32_t)));
	}

	private:
	A &_addressSpace;
	typename A::pint_t _addr;
	};

	template <typename A> class UnwindSectionLsdaArray {
	public:
	UnwindSectionLsdaArray(A &addressSpace, typename A::pint_t addr)
	: _addressSpace(addressSpace), _addr(addr) {}

	uint32_t functionOffset(uint32_t index) const {
	return _addressSpace.get32(
	_addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
	index, functionOffset));
	}
	uint32_t lsdaOffset(uint32_t index) const {
	return _addressSpace.get32(
	_addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
	index, lsdaOffset));
	}

	private:
	A &_addressSpace;
	typename A::pint_t _addr;
	};
	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)

	class _LIBUNWIND_HIDDEN AbstractUnwindCursor {
	public:
	// NOTE: provide a class specific placement deallocation function (S5.3.4 p20)
	// This avoids an unnecessary dependency to libc++abi.
	void operator delete(void *, size_t) {}

	virtual ~AbstractUnwindCursor() {}
	virtual bool validReg(int) { _LIBUNWIND_ABORT("validReg not implemented"); }
	virtual unw_word_t getReg(int) { _LIBUNWIND_ABORT("getReg not implemented"); }
	virtual void setReg(int, unw_word_t) {
	_LIBUNWIND_ABORT("setReg not implemented");
	}
	virtual bool validFloatReg(int) {
	_LIBUNWIND_ABORT("validFloatReg not implemented");
	}
	virtual unw_fpreg_t getFloatReg(int) {
	_LIBUNWIND_ABORT("getFloatReg not implemented");
	}
	virtual void setFloatReg(int, unw_fpreg_t) {
	_LIBUNWIND_ABORT("setFloatReg not implemented");
	}
	virtual int step(bool = false) { _LIBUNWIND_ABORT("step not implemented"); }
	virtual void getInfo(unw_proc_info_t *) {
	_LIBUNWIND_ABORT("getInfo not implemented");
	}
	virtual void jumpto() { _LIBUNWIND_ABORT("jumpto not implemented"); }
	virtual bool isSignalFrame() {
	_LIBUNWIND_ABORT("isSignalFrame not implemented");
	}
	virtual bool getFunctionName(char , size_t, unw_word_t ) {
	_LIBUNWIND_ABORT("getFunctionName not implemented");
	}
	virtual void setInfoBasedOnIPRegister(bool = false) {
	_LIBUNWIND_ABORT("setInfoBasedOnIPRegister not implemented");
	}
	virtual const char *getRegisterName(int) {
	_LIBUNWIND_ABORT("getRegisterName not implemented");
	}
	#ifdef __arm__
	virtual void saveVFPAsX() { _LIBUNWIND_ABORT("saveVFPAsX not implemented"); }
	#endif

	#ifdef _AIX
	virtual uintptr_t getDataRelBase() {
	_LIBUNWIND_ABORT("getDataRelBase not implemented");
	}
	#endif

	#if defined(_LIBUNWIND_USE_CET) \|\| defined(_LIBUNWIND_USE_GCS)
	virtual void *get_registers() {
	_LIBUNWIND_ABORT("get_registers not implemented");
	}
	#endif
	};

	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)

	/// \c UnwindCursor contains all state (including all register values) during
	/// an unwind. This is normally stack-allocated inside a unw_cursor_t.
	template <typename A, typename R>
	class UnwindCursor : public AbstractUnwindCursor {
	typedef typename A::pint_t pint_t;
	public:
	UnwindCursor(unw_context_t *context, A &as);
	UnwindCursor(CONTEXT *context, A &as);
	UnwindCursor(A &as, void *threadArg);
	virtual ~UnwindCursor() {}
	virtual bool validReg(int);
	virtual unw_word_t getReg(int);
	virtual void setReg(int, unw_word_t);
	virtual bool validFloatReg(int);
	virtual unw_fpreg_t getFloatReg(int);
	virtual void setFloatReg(int, unw_fpreg_t);
	virtual int step(bool = false);
	virtual void getInfo(unw_proc_info_t *);
	virtual void jumpto();
	virtual bool isSignalFrame();
	virtual bool getFunctionName(char buf, size_t len, unw_word_t off);
	virtual void setInfoBasedOnIPRegister(bool isReturnAddress = false);
	virtual const char *getRegisterName(int num);
	#ifdef __arm__
	virtual void saveVFPAsX();
	#endif

	DISPATCHER_CONTEXT *getDispatcherContext() { return &_dispContext; }
	void setDispatcherContext(DISPATCHER_CONTEXT *disp) {
	_dispContext = *disp;
	_info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
	if (_dispContext.LanguageHandler) {
	_info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
	} else
	_info.handler = 0;
	}

	// libunwind does not and should not depend on C++ library which means that we
	// need our own definition of inline placement new.
	static void operator new(size_t, UnwindCursor<A, R> p) { return p; }

	private:

	pint_t getLastPC() const { return _dispContext.ControlPc; }
	void setLastPC(pint_t pc) { _dispContext.ControlPc = pc; }
	RUNTIME_FUNCTION lookUpSEHUnwindInfo(pint_t pc, pint_t base) {
	#ifdef __arm__
	// Remove the thumb bit; FunctionEntry ranges don't include the thumb bit.
	pc &= ~1U;
	#endif
	// If pc points exactly at the end of the range, we might resolve the
	// next function instead. Decrement pc by 1 to fit inside the current
	// function.
	pc -= 1;
	_dispContext.FunctionEntry = RtlLookupFunctionEntry(pc,
	&_dispContext.ImageBase,
	_dispContext.HistoryTable);
	*base = _dispContext.ImageBase;
	return _dispContext.FunctionEntry;
	}
	bool getInfoFromSEH(pint_t pc);
	int stepWithSEHData() {
	_dispContext.LanguageHandler = RtlVirtualUnwind(UNW_FLAG_UHANDLER,
	_dispContext.ImageBase,
	_dispContext.ControlPc,
	_dispContext.FunctionEntry,
	_dispContext.ContextRecord,
	&_dispContext.HandlerData,
	&_dispContext.EstablisherFrame,
	NULL);
	// Update some fields of the unwind info now, since we have them.
	_info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
	if (_dispContext.LanguageHandler) {
	_info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
	} else
	_info.handler = 0;
	return UNW_STEP_SUCCESS;
	}

	A &_addressSpace;
	unw_proc_info_t _info;
	DISPATCHER_CONTEXT _dispContext;
	CONTEXT _msContext;
	UNWIND_HISTORY_TABLE _histTable;
	bool _unwindInfoMissing;
	};


	template <typename A, typename R>
	UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
	: _addressSpace(as), _unwindInfoMissing(false) {
	static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
	"UnwindCursor<> does not fit in unw_cursor_t");
	static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
	"UnwindCursor<> requires more alignment than unw_cursor_t");
	memset(&_info, 0, sizeof(_info));
	memset(&_histTable, 0, sizeof(_histTable));
	memset(&_dispContext, 0, sizeof(_dispContext));
	_dispContext.ContextRecord = &_msContext;
	_dispContext.HistoryTable = &_histTable;
	// Initialize MS context from ours.
	R r(context);
	RtlCaptureContext(&_msContext);
	_msContext.ContextFlags = CONTEXT_CONTROL\|CONTEXT_INTEGER\|CONTEXT_FLOATING_POINT;
	#if defined(_LIBUNWIND_TARGET_X86_64)
	_msContext.Rax = r.getRegister(UNW_X86_64_RAX);
	_msContext.Rcx = r.getRegister(UNW_X86_64_RCX);
	_msContext.Rdx = r.getRegister(UNW_X86_64_RDX);
	_msContext.Rbx = r.getRegister(UNW_X86_64_RBX);
	_msContext.Rsp = r.getRegister(UNW_X86_64_RSP);
	_msContext.Rbp = r.getRegister(UNW_X86_64_RBP);
	_msContext.Rsi = r.getRegister(UNW_X86_64_RSI);
	_msContext.Rdi = r.getRegister(UNW_X86_64_RDI);
	_msContext.R8 = r.getRegister(UNW_X86_64_R8);
	_msContext.R9 = r.getRegister(UNW_X86_64_R9);
	_msContext.R10 = r.getRegister(UNW_X86_64_R10);
	_msContext.R11 = r.getRegister(UNW_X86_64_R11);
	_msContext.R12 = r.getRegister(UNW_X86_64_R12);
	_msContext.R13 = r.getRegister(UNW_X86_64_R13);
	_msContext.R14 = r.getRegister(UNW_X86_64_R14);
	_msContext.R15 = r.getRegister(UNW_X86_64_R15);
	_msContext.Rip = r.getRegister(UNW_REG_IP);
	union {
	v128 v;
	M128A m;
	} t;
	t.v = r.getVectorRegister(UNW_X86_64_XMM0);
	_msContext.Xmm0 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM1);
	_msContext.Xmm1 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM2);
	_msContext.Xmm2 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM3);
	_msContext.Xmm3 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM4);
	_msContext.Xmm4 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM5);
	_msContext.Xmm5 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM6);
	_msContext.Xmm6 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM7);
	_msContext.Xmm7 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM8);
	_msContext.Xmm8 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM9);
	_msContext.Xmm9 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM10);
	_msContext.Xmm10 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM11);
	_msContext.Xmm11 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM12);
	_msContext.Xmm12 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM13);
	_msContext.Xmm13 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM14);
	_msContext.Xmm14 = t.m;
	t.v = r.getVectorRegister(UNW_X86_64_XMM15);
	_msContext.Xmm15 = t.m;
	#elif defined(_LIBUNWIND_TARGET_ARM)
	_msContext.R0 = r.getRegister(UNW_ARM_R0);
	_msContext.R1 = r.getRegister(UNW_ARM_R1);
	_msContext.R2 = r.getRegister(UNW_ARM_R2);
	_msContext.R3 = r.getRegister(UNW_ARM_R3);
	_msContext.R4 = r.getRegister(UNW_ARM_R4);
	_msContext.R5 = r.getRegister(UNW_ARM_R5);
	_msContext.R6 = r.getRegister(UNW_ARM_R6);
	_msContext.R7 = r.getRegister(UNW_ARM_R7);
	_msContext.R8 = r.getRegister(UNW_ARM_R8);
	_msContext.R9 = r.getRegister(UNW_ARM_R9);
	_msContext.R10 = r.getRegister(UNW_ARM_R10);
	_msContext.R11 = r.getRegister(UNW_ARM_R11);
	_msContext.R12 = r.getRegister(UNW_ARM_R12);
	_msContext.Sp = r.getRegister(UNW_ARM_SP);
	_msContext.Lr = r.getRegister(UNW_ARM_LR);
	_msContext.Pc = r.getRegister(UNW_ARM_IP);
	for (int i = UNW_ARM_D0; i <= UNW_ARM_D31; ++i) {
	union {
	uint64_t w;
	double d;
	} d;
	d.d = r.getFloatRegister(i);
	_msContext.D[i - UNW_ARM_D0] = d.w;
	}
	#elif defined(_LIBUNWIND_TARGET_AARCH64)
	for (int i = UNW_AARCH64_X0; i <= UNW_ARM64_X30; ++i)
	_msContext.X[i - UNW_AARCH64_X0] = r.getRegister(i);
	_msContext.Sp = r.getRegister(UNW_REG_SP);
	_msContext.Pc = r.getRegister(UNW_REG_IP);
	for (int i = UNW_AARCH64_V0; i <= UNW_ARM64_D31; ++i)
	_msContext.V[i - UNW_AARCH64_V0].D[0] = r.getFloatRegister(i);
	#endif
	}

	template <typename A, typename R>
	UnwindCursor<A, R>::UnwindCursor(CONTEXT *context, A &as)
	: _addressSpace(as), _unwindInfoMissing(false) {
	static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
	"UnwindCursor<> does not fit in unw_cursor_t");
	memset(&_info, 0, sizeof(_info));
	memset(&_histTable, 0, sizeof(_histTable));
	memset(&_dispContext, 0, sizeof(_dispContext));
	_dispContext.ContextRecord = &_msContext;
	_dispContext.HistoryTable = &_histTable;
	_msContext = *context;
	}


	template <typename A, typename R>
	bool UnwindCursor<A, R>::validReg(int regNum) {
	if (regNum == UNW_REG_IP \|\| regNum == UNW_REG_SP) return true;
	#if defined(_LIBUNWIND_TARGET_X86_64)
	if (regNum >= UNW_X86_64_RAX && regNum <= UNW_X86_64_RIP) return true;
	#elif defined(_LIBUNWIND_TARGET_ARM)
	if ((regNum >= UNW_ARM_R0 && regNum <= UNW_ARM_R15) \|\|
	regNum == UNW_ARM_RA_AUTH_CODE)
	return true;
	#elif defined(_LIBUNWIND_TARGET_AARCH64)
	if (regNum >= UNW_AARCH64_X0 && regNum <= UNW_ARM64_X30) return true;
	#endif
	return false;
	}

	template <typename A, typename R>
	unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
	switch (regNum) {
	#if defined(_LIBUNWIND_TARGET_X86_64)
	case UNW_X86_64_RIP:
	case UNW_REG_IP: return _msContext.Rip;
	case UNW_X86_64_RAX: return _msContext.Rax;
	case UNW_X86_64_RDX: return _msContext.Rdx;
	case UNW_X86_64_RCX: return _msContext.Rcx;
	case UNW_X86_64_RBX: return _msContext.Rbx;
	case UNW_REG_SP:
	case UNW_X86_64_RSP: return _msContext.Rsp;
	case UNW_X86_64_RBP: return _msContext.Rbp;
	case UNW_X86_64_RSI: return _msContext.Rsi;
	case UNW_X86_64_RDI: return _msContext.Rdi;
	case UNW_X86_64_R8: return _msContext.R8;
	case UNW_X86_64_R9: return _msContext.R9;
	case UNW_X86_64_R10: return _msContext.R10;
	case UNW_X86_64_R11: return _msContext.R11;
	case UNW_X86_64_R12: return _msContext.R12;
	case UNW_X86_64_R13: return _msContext.R13;
	case UNW_X86_64_R14: return _msContext.R14;
	case UNW_X86_64_R15: return _msContext.R15;
	#elif defined(_LIBUNWIND_TARGET_ARM)
	case UNW_ARM_R0: return _msContext.R0;
	case UNW_ARM_R1: return _msContext.R1;
	case UNW_ARM_R2: return _msContext.R2;
	case UNW_ARM_R3: return _msContext.R3;
	case UNW_ARM_R4: return _msContext.R4;
	case UNW_ARM_R5: return _msContext.R5;
	case UNW_ARM_R6: return _msContext.R6;
	case UNW_ARM_R7: return _msContext.R7;
	case UNW_ARM_R8: return _msContext.R8;
	case UNW_ARM_R9: return _msContext.R9;
	case UNW_ARM_R10: return _msContext.R10;
	case UNW_ARM_R11: return _msContext.R11;
	case UNW_ARM_R12: return _msContext.R12;
	case UNW_REG_SP:
	case UNW_ARM_SP: return _msContext.Sp;
	case UNW_ARM_LR: return _msContext.Lr;
	case UNW_REG_IP:
	case UNW_ARM_IP: return _msContext.Pc;
	#elif defined(_LIBUNWIND_TARGET_AARCH64)
	case UNW_REG_SP: return _msContext.Sp;
	case UNW_REG_IP: return _msContext.Pc;
	default: return _msContext.X[regNum - UNW_AARCH64_X0];
	#endif
	}
	_LIBUNWIND_ABORT("unsupported register");
	}

	template <typename A, typename R>
	void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
	switch (regNum) {
	#if defined(_LIBUNWIND_TARGET_X86_64)
	case UNW_X86_64_RIP:
	case UNW_REG_IP: _msContext.Rip = value; break;
	case UNW_X86_64_RAX: _msContext.Rax = value; break;
	case UNW_X86_64_RDX: _msContext.Rdx = value; break;
	case UNW_X86_64_RCX: _msContext.Rcx = value; break;
	case UNW_X86_64_RBX: _msContext.Rbx = value; break;
	case UNW_REG_SP:
	case UNW_X86_64_RSP: _msContext.Rsp = value; break;
	case UNW_X86_64_RBP: _msContext.Rbp = value; break;
	case UNW_X86_64_RSI: _msContext.Rsi = value; break;
	case UNW_X86_64_RDI: _msContext.Rdi = value; break;
	case UNW_X86_64_R8: _msContext.R8 = value; break;
	case UNW_X86_64_R9: _msContext.R9 = value; break;
	case UNW_X86_64_R10: _msContext.R10 = value; break;
	case UNW_X86_64_R11: _msContext.R11 = value; break;
	case UNW_X86_64_R12: _msContext.R12 = value; break;
	case UNW_X86_64_R13: _msContext.R13 = value; break;
	case UNW_X86_64_R14: _msContext.R14 = value; break;
	case UNW_X86_64_R15: _msContext.R15 = value; break;
	#elif defined(_LIBUNWIND_TARGET_ARM)
	case UNW_ARM_R0: _msContext.R0 = value; break;
	case UNW_ARM_R1: _msContext.R1 = value; break;
	case UNW_ARM_R2: _msContext.R2 = value; break;
	case UNW_ARM_R3: _msContext.R3 = value; break;
	case UNW_ARM_R4: _msContext.R4 = value; break;
	case UNW_ARM_R5: _msContext.R5 = value; break;
	case UNW_ARM_R6: _msContext.R6 = value; break;
	case UNW_ARM_R7: _msContext.R7 = value; break;
	case UNW_ARM_R8: _msContext.R8 = value; break;
	case UNW_ARM_R9: _msContext.R9 = value; break;
	case UNW_ARM_R10: _msContext.R10 = value; break;
	case UNW_ARM_R11: _msContext.R11 = value; break;
	case UNW_ARM_R12: _msContext.R12 = value; break;
	case UNW_REG_SP:
	case UNW_ARM_SP: _msContext.Sp = value; break;
	case UNW_ARM_LR: _msContext.Lr = value; break;
	case UNW_REG_IP:
	case UNW_ARM_IP: _msContext.Pc = value; break;
	#elif defined(_LIBUNWIND_TARGET_AARCH64)
	case UNW_REG_SP: _msContext.Sp = value; break;
	case UNW_REG_IP: _msContext.Pc = value; break;
	case UNW_AARCH64_X0:
	case UNW_AARCH64_X1:
	case UNW_AARCH64_X2:
	case UNW_AARCH64_X3:
	case UNW_AARCH64_X4:
	case UNW_AARCH64_X5:
	case UNW_AARCH64_X6:
	case UNW_AARCH64_X7:
	case UNW_AARCH64_X8:
	case UNW_AARCH64_X9:
	case UNW_AARCH64_X10:
	case UNW_AARCH64_X11:
	case UNW_AARCH64_X12:
	case UNW_AARCH64_X13:
	case UNW_AARCH64_X14:
	case UNW_AARCH64_X15:
	case UNW_AARCH64_X16:
	case UNW_AARCH64_X17:
	case UNW_AARCH64_X18:
	case UNW_AARCH64_X19:
	case UNW_AARCH64_X20:
	case UNW_AARCH64_X21:
	case UNW_AARCH64_X22:
	case UNW_AARCH64_X23:
	case UNW_AARCH64_X24:
	case UNW_AARCH64_X25:
	case UNW_AARCH64_X26:
	case UNW_AARCH64_X27:
	case UNW_AARCH64_X28:
	case UNW_AARCH64_FP:
	case UNW_AARCH64_LR: _msContext.X[regNum - UNW_ARM64_X0] = value; break;
	#endif
	default:
	_LIBUNWIND_ABORT("unsupported register");
	}
	}

	template <typename A, typename R>
	bool UnwindCursor<A, R>::validFloatReg(int regNum) {
	#if defined(_LIBUNWIND_TARGET_ARM)
	if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) return true;
	if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) return true;
	#elif defined(_LIBUNWIND_TARGET_AARCH64)
	if (regNum >= UNW_AARCH64_V0 && regNum <= UNW_ARM64_D31) return true;
	#else
	(void)regNum;
	#endif
	return false;
	}

	template <typename A, typename R>
	unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
	#if defined(_LIBUNWIND_TARGET_ARM)
	if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
	union {
	uint32_t w;
	float f;
	} d;
	d.w = _msContext.S[regNum - UNW_ARM_S0];
	return d.f;
	}
	if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
	union {
	uint64_t w;
	double d;
	} d;
	d.w = _msContext.D[regNum - UNW_ARM_D0];
	return d.d;
	}
	_LIBUNWIND_ABORT("unsupported float register");
	#elif defined(_LIBUNWIND_TARGET_AARCH64)
	return _msContext.V[regNum - UNW_AARCH64_V0].D[0];
	#else
	(void)regNum;
	_LIBUNWIND_ABORT("float registers unimplemented");
	#endif
	}

	template <typename A, typename R>
	void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
	#if defined(_LIBUNWIND_TARGET_ARM)
	if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
	union {
	uint32_t w;
	float f;
	} d;
	d.f = (float)value;
	_msContext.S[regNum - UNW_ARM_S0] = d.w;
	}
	if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
	union {
	uint64_t w;
	double d;
	} d;
	d.d = value;
	_msContext.D[regNum - UNW_ARM_D0] = d.w;
	}
	_LIBUNWIND_ABORT("unsupported float register");
	#elif defined(_LIBUNWIND_TARGET_AARCH64)
	_msContext.V[regNum - UNW_AARCH64_V0].D[0] = value;
	#else
	(void)regNum;
	(void)value;
	_LIBUNWIND_ABORT("float registers unimplemented");
	#endif
	}

	template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
	RtlRestoreContext(&_msContext, nullptr);
	}

	#ifdef __arm__
	template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {}
	#endif

	template <typename A, typename R>
	const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
	return R::getRegisterName(regNum);
	}

	template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
	return false;
	}

	#else // !defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) \|\| !defined(_WIN32)

	/// UnwindCursor contains all state (including all register values) during
	/// an unwind. This is normally stack allocated inside a unw_cursor_t.
	template <typename A, typename R>
	class UnwindCursor : public AbstractUnwindCursor{
	typedef typename A::pint_t pint_t;
	public:
	UnwindCursor(unw_context_t *context, A &as);
	UnwindCursor(A &as, void *threadArg);
	virtual ~UnwindCursor() {}
	virtual bool validReg(int);
	virtual unw_word_t getReg(int);
	virtual void setReg(int, unw_word_t);
	virtual bool validFloatReg(int);
	virtual unw_fpreg_t getFloatReg(int);
	virtual void setFloatReg(int, unw_fpreg_t);
	virtual int step(bool stage2 = false);
	virtual void getInfo(unw_proc_info_t *);
	virtual void jumpto();
	virtual bool isSignalFrame();
	virtual bool getFunctionName(char buf, size_t len, unw_word_t off);
	virtual void setInfoBasedOnIPRegister(bool isReturnAddress = false);
	virtual const char *getRegisterName(int num);
	#ifdef __arm__
	virtual void saveVFPAsX();
	#endif

	#ifdef _AIX
	virtual uintptr_t getDataRelBase();
	#endif

	#if defined(_LIBUNWIND_USE_CET) \|\| defined(_LIBUNWIND_USE_GCS)
	virtual void *get_registers() { return &_registers; }
	#endif

	// libunwind does not and should not depend on C++ library which means that we
	// need our own definition of inline placement new.
	static void operator new(size_t, UnwindCursor<A, R> p) { return p; }

	private:

	#if defined(_LIBUNWIND_ARM_EHABI)
	bool getInfoFromEHABISection(pint_t pc, const UnwindInfoSections &sects);

	int stepWithEHABI() {
	size_t len = 0;
	size_t off = 0;
	// FIXME: Calling decode_eht_entry() here is violating the libunwind
	// abstraction layer.
	const uint32_t *ehtp =
	decode_eht_entry(reinterpret_cast<const uint32_t *>(_info.unwind_info),
	&off, &len);
	if (_Unwind_VRS_Interpret((_Unwind_Context *)this, ehtp, off, len) !=
	_URC_CONTINUE_UNWIND)
	return UNW_STEP_END;
	return UNW_STEP_SUCCESS;
	}
	#endif

	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
	bool setInfoForSigReturn() {
	R dummy;
	return setInfoForSigReturn(dummy);
	}
	int stepThroughSigReturn() {
	R dummy;
	return stepThroughSigReturn(dummy);
	}
	bool isReadableAddr(const pint_t addr) const;
	#if defined(_LIBUNWIND_TARGET_AARCH64)
	bool setInfoForSigReturn(Registers_arm64 &);
	int stepThroughSigReturn(Registers_arm64 &);
	#endif
	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
	bool setInfoForSigReturn(Registers_loongarch &);
	int stepThroughSigReturn(Registers_loongarch &);
	#endif
	#if defined(_LIBUNWIND_TARGET_RISCV)
	bool setInfoForSigReturn(Registers_riscv &);
	int stepThroughSigReturn(Registers_riscv &);
	#endif
	#if defined(_LIBUNWIND_TARGET_S390X)
	bool setInfoForSigReturn(Registers_s390x &);
	int stepThroughSigReturn(Registers_s390x &);
	#endif
	template <typename Registers> bool setInfoForSigReturn(Registers &) {
	return false;
	}
	template <typename Registers> int stepThroughSigReturn(Registers &) {
	return UNW_STEP_END;
	}
	#elif defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
	bool setInfoForSigReturn();
	int stepThroughSigReturn();
	#endif

	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
	bool getInfoFromFdeCie(const typename CFI_Parser<A>::FDE_Info &fdeInfo,
	const typename CFI_Parser<A>::CIE_Info &cieInfo,
	pint_t pc, uintptr_t dso_base);
	bool getInfoFromDwarfSection(pint_t pc, const UnwindInfoSections &sects,
	uint32_t fdeSectionOffsetHint=0);
	int stepWithDwarfFDE(bool stage2) {
	return DwarfInstructions<A, R>::stepWithDwarf(
	_addressSpace, (pint_t)this->getReg(UNW_REG_IP),
	(pint_t)_info.unwind_info, _registers, _isSignalFrame, stage2);
	}
	#endif

	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
	bool getInfoFromCompactEncodingSection(pint_t pc,
	const UnwindInfoSections &sects);
	int stepWithCompactEncoding(bool stage2 = false) {
	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
	if ( compactSaysUseDwarf() )
	return stepWithDwarfFDE(stage2);
	#endif
	R dummy;
	return stepWithCompactEncoding(dummy);
	}

	#if defined(_LIBUNWIND_TARGET_X86_64)
	int stepWithCompactEncoding(Registers_x86_64 &) {
	return CompactUnwinder_x86_64<A>::stepWithCompactEncoding(
	_info.format, _info.start_ip, _addressSpace, _registers);
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_I386)
	int stepWithCompactEncoding(Registers_x86 &) {
	return CompactUnwinder_x86<A>::stepWithCompactEncoding(
	_info.format, (uint32_t)_info.start_ip, _addressSpace, _registers);
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_PPC)
	int stepWithCompactEncoding(Registers_ppc &) {
	return UNW_EINVAL;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_PPC64)
	int stepWithCompactEncoding(Registers_ppc64 &) {
	return UNW_EINVAL;
	}
	#endif


	#if defined(_LIBUNWIND_TARGET_AARCH64)
	int stepWithCompactEncoding(Registers_arm64 &) {
	return CompactUnwinder_arm64<A>::stepWithCompactEncoding(
	_info.format, _info.start_ip, _addressSpace, _registers);
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_MIPS_O32)
	int stepWithCompactEncoding(Registers_mips_o32 &) {
	return UNW_EINVAL;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
	int stepWithCompactEncoding(Registers_mips_newabi &) {
	return UNW_EINVAL;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
	int stepWithCompactEncoding(Registers_loongarch &) { return UNW_EINVAL; }
	#endif

	#if defined(_LIBUNWIND_TARGET_SPARC)
	int stepWithCompactEncoding(Registers_sparc &) { return UNW_EINVAL; }
	#endif

	#if defined(_LIBUNWIND_TARGET_SPARC64)
	int stepWithCompactEncoding(Registers_sparc64 &) { return UNW_EINVAL; }
	#endif

	#if defined (_LIBUNWIND_TARGET_RISCV)
	int stepWithCompactEncoding(Registers_riscv &) {
	return UNW_EINVAL;
	}
	#endif

	bool compactSaysUseDwarf(uint32_t *offset=NULL) const {
	R dummy;
	return compactSaysUseDwarf(dummy, offset);
	}

	#if defined(_LIBUNWIND_TARGET_X86_64)
	bool compactSaysUseDwarf(Registers_x86_64 &, uint32_t *offset) const {
	if ((_info.format & UNWIND_X86_64_MODE_MASK) == UNWIND_X86_64_MODE_DWARF) {
	if (offset)
	*offset = (_info.format & UNWIND_X86_64_DWARF_SECTION_OFFSET);
	return true;
	}
	return false;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_I386)
	bool compactSaysUseDwarf(Registers_x86 &, uint32_t *offset) const {
	if ((_info.format & UNWIND_X86_MODE_MASK) == UNWIND_X86_MODE_DWARF) {
	if (offset)
	*offset = (_info.format & UNWIND_X86_DWARF_SECTION_OFFSET);
	return true;
	}
	return false;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_PPC)
	bool compactSaysUseDwarf(Registers_ppc &, uint32_t *) const {
	return true;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_PPC64)
	bool compactSaysUseDwarf(Registers_ppc64 &, uint32_t *) const {
	return true;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_AARCH64)
	bool compactSaysUseDwarf(Registers_arm64 &, uint32_t *offset) const {
	if ((_info.format & UNWIND_ARM64_MODE_MASK) == UNWIND_ARM64_MODE_DWARF) {
	if (offset)
	*offset = (_info.format & UNWIND_ARM64_DWARF_SECTION_OFFSET);
	return true;
	}
	return false;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_MIPS_O32)
	bool compactSaysUseDwarf(Registers_mips_o32 &, uint32_t *) const {
	return true;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
	bool compactSaysUseDwarf(Registers_mips_newabi &, uint32_t *) const {
	return true;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
	bool compactSaysUseDwarf(Registers_loongarch &, uint32_t *) const {
	return true;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_SPARC)
	bool compactSaysUseDwarf(Registers_sparc &, uint32_t *) const { return true; }
	#endif

	#if defined(_LIBUNWIND_TARGET_SPARC64)
	bool compactSaysUseDwarf(Registers_sparc64 &, uint32_t *) const {
	return true;
	}
	#endif

	#if defined (_LIBUNWIND_TARGET_RISCV)
	bool compactSaysUseDwarf(Registers_riscv &, uint32_t *) const {
	return true;
	}
	#endif

	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)

	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
	compact_unwind_encoding_t dwarfEncoding() const {
	R dummy;
	return dwarfEncoding(dummy);
	}

	#if defined(_LIBUNWIND_TARGET_X86_64)
	compact_unwind_encoding_t dwarfEncoding(Registers_x86_64 &) const {
	return UNWIND_X86_64_MODE_DWARF;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_I386)
	compact_unwind_encoding_t dwarfEncoding(Registers_x86 &) const {
	return UNWIND_X86_MODE_DWARF;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_PPC)
	compact_unwind_encoding_t dwarfEncoding(Registers_ppc &) const {
	return 0;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_PPC64)
	compact_unwind_encoding_t dwarfEncoding(Registers_ppc64 &) const {
	return 0;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_AARCH64)
	compact_unwind_encoding_t dwarfEncoding(Registers_arm64 &) const {
	return UNWIND_ARM64_MODE_DWARF;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_ARM)
	compact_unwind_encoding_t dwarfEncoding(Registers_arm &) const {
	return 0;
	}
	#endif

	#if defined (_LIBUNWIND_TARGET_OR1K)
	compact_unwind_encoding_t dwarfEncoding(Registers_or1k &) const {
	return 0;
	}
	#endif

	#if defined (_LIBUNWIND_TARGET_HEXAGON)
	compact_unwind_encoding_t dwarfEncoding(Registers_hexagon &) const {
	return 0;
	}
	#endif

	#if defined (_LIBUNWIND_TARGET_MIPS_O32)
	compact_unwind_encoding_t dwarfEncoding(Registers_mips_o32 &) const {
	return 0;
	}
	#endif

	#if defined (_LIBUNWIND_TARGET_MIPS_NEWABI)
	compact_unwind_encoding_t dwarfEncoding(Registers_mips_newabi &) const {
	return 0;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
	compact_unwind_encoding_t dwarfEncoding(Registers_loongarch &) const {
	return 0;
	}
	#endif

	#if defined(_LIBUNWIND_TARGET_SPARC)
	compact_unwind_encoding_t dwarfEncoding(Registers_sparc &) const { return 0; }
	#endif

	#if defined(_LIBUNWIND_TARGET_SPARC64)
	compact_unwind_encoding_t dwarfEncoding(Registers_sparc64 &) const {
	return 0;
	}
	#endif

	#if defined (_LIBUNWIND_TARGET_RISCV)
	compact_unwind_encoding_t dwarfEncoding(Registers_riscv &) const {
	return 0;
	}
	#endif

	#if defined (_LIBUNWIND_TARGET_S390X)
	compact_unwind_encoding_t dwarfEncoding(Registers_s390x &) const {
	return 0;
	}
	#endif

	#endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)

	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
	// For runtime environments using SEH unwind data without Windows runtime
	// support.
	pint_t getLastPC() const { /* FIXME: Implement */ return 0; }
	void setLastPC(pint_t pc) { /* FIXME: Implement */ }
	RUNTIME_FUNCTION lookUpSEHUnwindInfo(pint_t pc, pint_t base) {
	/* FIXME: Implement */
	*base = 0;
	return nullptr;
	}
	bool getInfoFromSEH(pint_t pc);
	int stepWithSEHData() { /* FIXME: Implement */ return 0; }
	#endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)

	#if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
	bool getInfoFromTBTable(pint_t pc, R &registers);
	int stepWithTBTable(pint_t pc, tbtable *TBTable, R &registers,
	bool &isSignalFrame);
	int stepWithTBTableData() {
	return stepWithTBTable(reinterpret_cast<pint_t>(this->getReg(UNW_REG_IP)),
	reinterpret_cast<tbtable *>(_info.unwind_info),
	_registers, _isSignalFrame);
	}
	#endif // defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)

	A &_addressSpace;
	R _registers;
	unw_proc_info_t _info;
	bool _unwindInfoMissing;
	bool _isSignalFrame;
	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
	defined(_LIBUNWIND_TARGET_HAIKU)
	bool _isSigReturn = false;
	#endif
	};


	template <typename A, typename R>
	UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
	: _addressSpace(as), _registers(context), _unwindInfoMissing(false),
	_isSignalFrame(false) {
	static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
	"UnwindCursor<> does not fit in unw_cursor_t");
	static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
	"UnwindCursor<> requires more alignment than unw_cursor_t");
	memset(&_info, 0, sizeof(_info));
	}

	template <typename A, typename R>
	UnwindCursor<A, R>::UnwindCursor(A &as, void *)
	: _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false) {
	memset(&_info, 0, sizeof(_info));
	// FIXME
	// fill in _registers from thread arg
	}


	template <typename A, typename R>
	bool UnwindCursor<A, R>::validReg(int regNum) {
	return _registers.validRegister(regNum);
	}

	template <typename A, typename R>
	unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
	return _registers.getRegister(regNum);
	}

	template <typename A, typename R>
	void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
	_registers.setRegister(regNum, (typename A::pint_t)value);
	}

	template <typename A, typename R>
	bool UnwindCursor<A, R>::validFloatReg(int regNum) {
	return _registers.validFloatRegister(regNum);
	}

	template <typename A, typename R>
	unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
	return _registers.getFloatRegister(regNum);
	}

	template <typename A, typename R>
	void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
	_registers.setFloatRegister(regNum, value);
	}

	template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
	_registers.jumpto();
	}

	#ifdef __arm__
	template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {
	_registers.saveVFPAsX();
	}
	#endif

	#ifdef _AIX
	template <typename A, typename R>
	uintptr_t UnwindCursor<A, R>::getDataRelBase() {
	return reinterpret_cast<uintptr_t>(_info.extra);
	}
	#endif

	template <typename A, typename R>
	const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
	return _registers.getRegisterName(regNum);
	}

	template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
	return _isSignalFrame;
	}

	#endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)

	#if defined(_LIBUNWIND_ARM_EHABI)
	template<typename A>
	struct EHABISectionIterator {
	typedef EHABISectionIterator _Self;

	typedef typename A::pint_t value_type;
	typedef typename A::pint_t* pointer;
	typedef typename A::pint_t& reference;
	typedef size_t size_type;
	typedef size_t difference_type;

	static _Self begin(A& addressSpace, const UnwindInfoSections& sects) {
	return _Self(addressSpace, sects, 0);
	}
	static _Self end(A& addressSpace, const UnwindInfoSections& sects) {
	return _Self(addressSpace, sects,
	sects.arm_section_length / sizeof(EHABIIndexEntry));
	}

	EHABISectionIterator(A& addressSpace, const UnwindInfoSections& sects, size_t i)
	: _i(i), _addressSpace(&addressSpace), _sects(&sects) {}

	_Self& operator++() { ++_i; return *this; }
	_Self& operator+=(size_t a) { _i += a; return *this; }
	_Self& operator--() { assert(_i > 0); --_i; return *this; }
	_Self& operator-=(size_t a) { assert(_i >= a); _i -= a; return *this; }

	_Self operator+(size_t a) { _Self out = *this; out._i += a; return out; }
	_Self operator-(size_t a) { assert(_i >= a); _Self out = *this; out._i -= a; return out; }

	size_t operator-(const _Self& other) const { return _i - other._i; }

	bool operator==(const _Self& other) const {
	assert(_addressSpace == other._addressSpace);
	assert(_sects == other._sects);
	return _i == other._i;
	}

	bool operator!=(const _Self& other) const {
	assert(_addressSpace == other._addressSpace);
	assert(_sects == other._sects);
	return _i != other._i;
	}

	typename A::pint_t operator*() const { return functionAddress(); }

	typename A::pint_t functionAddress() const {
	typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
	EHABIIndexEntry, _i, functionOffset);
	return indexAddr + signExtendPrel31(_addressSpace->get32(indexAddr));
	}

	typename A::pint_t dataAddress() {
	typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
	EHABIIndexEntry, _i, data);
	return indexAddr;
	}

	private:
	size_t _i;
	A* _addressSpace;
	const UnwindInfoSections* _sects;
	};

	namespace {

	template <typename A>
	EHABISectionIterator<A> EHABISectionUpperBound(
	EHABISectionIterator<A> first,
	EHABISectionIterator<A> last,
	typename A::pint_t value) {
	size_t len = last - first;
	while (len > 0) {
	size_t l2 = len / 2;
	EHABISectionIterator<A> m = first + l2;
	if (value < *m) {
	len = l2;
	} else {
	first = ++m;
	len -= l2 + 1;
	}
	}
	return first;
	}

	}

	template <typename A, typename R>
	bool UnwindCursor<A, R>::getInfoFromEHABISection(
	pint_t pc,
	const UnwindInfoSections &sects) {
	EHABISectionIterator<A> begin =
	EHABISectionIterator<A>::begin(_addressSpace, sects);
	EHABISectionIterator<A> end =
	EHABISectionIterator<A>::end(_addressSpace, sects);
	if (begin == end)
	return false;

	EHABISectionIterator<A> itNextPC = EHABISectionUpperBound(begin, end, pc);
	if (itNextPC == begin)
	return false;
	EHABISectionIterator<A> itThisPC = itNextPC - 1;

	pint_t thisPC = itThisPC.functionAddress();
	// If an exception is thrown from a function, corresponding to the last entry
	// in the table, we don't really know the function extent and have to choose a
	// value for nextPC. Choosing max() will allow the range check during trace to
	// succeed.
	pint_t nextPC = (itNextPC == end) ? UINTPTR_MAX : itNextPC.functionAddress();
	pint_t indexDataAddr = itThisPC.dataAddress();

	if (indexDataAddr == 0)
	return false;

	uint32_t indexData = _addressSpace.get32(indexDataAddr);
	if (indexData == UNW_EXIDX_CANTUNWIND)
	return false;

	// If the high bit is set, the exception handling table entry is inline inside
	// the index table entry on the second word (aka \|indexDataAddr\|). Otherwise,
	// the table points at an offset in the exception handling table (section 5
	// EHABI).
	pint_t exceptionTableAddr;
	uint32_t exceptionTableData;
	bool isSingleWordEHT;
	if (indexData & 0x80000000) {
	exceptionTableAddr = indexDataAddr;
	// TODO(ajwong): Should this data be 0?
	exceptionTableData = indexData;
	isSingleWordEHT = true;
	} else {
	exceptionTableAddr = indexDataAddr + signExtendPrel31(indexData);
	exceptionTableData = _addressSpace.get32(exceptionTableAddr);
	isSingleWordEHT = false;
	}

	// Now we know the 3 things:
	// exceptionTableAddr -- exception handler table entry.
	// exceptionTableData -- the data inside the first word of the eht entry.
	// isSingleWordEHT -- whether the entry is in the index.
	unw_word_t personalityRoutine = 0xbadf00d;
	bool scope32 = false;
	uintptr_t lsda;

	// If the high bit in the exception handling table entry is set, the entry is
	// in compact form (section 6.3 EHABI).
	if (exceptionTableData & 0x80000000) {
	// Grab the index of the personality routine from the compact form.
	uint32_t choice = (exceptionTableData & 0x0f000000) >> 24;
	uint32_t extraWords = 0;
	switch (choice) {
	case 0:
	personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr0;
	extraWords = 0;
	scope32 = false;
	lsda = isSingleWordEHT ? 0 : (exceptionTableAddr + 4);
	break;
	case 1:
	personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr1;
	extraWords = (exceptionTableData & 0x00ff0000) >> 16;
	scope32 = false;
	lsda = exceptionTableAddr + (extraWords + 1) * 4;
	break;
	case 2:
	personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr2;
	extraWords = (exceptionTableData & 0x00ff0000) >> 16;
	scope32 = true;
	lsda = exceptionTableAddr + (extraWords + 1) * 4;
	break;
	default:
	_LIBUNWIND_ABORT("unknown personality routine");
	return false;
	}

	if (isSingleWordEHT) {
	if (extraWords != 0) {
	_LIBUNWIND_ABORT("index inlined table detected but pr function "
	"requires extra words");
	return false;
	}
	}
	} else {
	pint_t personalityAddr =
	exceptionTableAddr + signExtendPrel31(exceptionTableData);
	personalityRoutine = personalityAddr;

	// ARM EHABI # 6.2, # 9.2
	//
	// +---- ehtp
	// v
	// +--------------------------------------+
	// \| +--------+--------+--------+-------+ \|
	// \| \|0\| prel31 to personalityRoutine \| \|
	// \| +--------+--------+--------+-------+ \|
	// \| \| N \| unwind opcodes \| \| <-- UnwindData
	// \| +--------+--------+--------+-------+ \|
	// \| \| Word 2 unwind opcodes \| \|
	// \| +--------+--------+--------+-------+ \|
	// \| ... \|
	// \| +--------+--------+--------+-------+ \|
	// \| \| Word N unwind opcodes \| \|
	// \| +--------+--------+--------+-------+ \|
	// \| \| LSDA \| \| <-- lsda
	// \| \| ... \| \|
	// \| +--------+--------+--------+-------+ \|
	// +--------------------------------------+

	uint32_t UnwindData = reinterpret_cast<uint32_t>(exceptionTableAddr) + 1;
	uint32_t FirstDataWord = *UnwindData;
	size_t N = ((FirstDataWord >> 24) & 0xff);
	size_t NDataWords = N + 1;
	lsda = reinterpret_cast<uintptr_t>(UnwindData + NDataWords);
	}

	_info.start_ip = thisPC;
	_info.end_ip = nextPC;
	_info.handler = personalityRoutine;
	_info.unwind_info = exceptionTableAddr;
	_info.lsda = lsda;
	// flags is pr_cache.additional. See EHABI #7.2 for definition of bit 0.
	_info.flags = (isSingleWordEHT ? 1 : 0) \| (scope32 ? 0x2 : 0); // Use enum?

	return true;
	}
	#endif

	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
	template <typename A, typename R>
	bool UnwindCursor<A, R>::getInfoFromFdeCie(
	const typename CFI_Parser<A>::FDE_Info &fdeInfo,
	const typename CFI_Parser<A>::CIE_Info &cieInfo, pint_t pc,
	uintptr_t dso_base) {
	typename CFI_Parser<A>::PrologInfo prolog;
	if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo, pc,
	R::getArch(), &prolog)) {
	// Save off parsed FDE info
	_info.start_ip = fdeInfo.pcStart;
	_info.end_ip = fdeInfo.pcEnd;
	_info.lsda = fdeInfo.lsda;
	_info.handler = cieInfo.personality;
	// Some frameless functions need SP altered when resuming in function, so
	// propagate spExtraArgSize.
	_info.gp = prolog.spExtraArgSize;
	_info.flags = 0;
	_info.format = dwarfEncoding();
	_info.unwind_info = fdeInfo.fdeStart;
	_info.unwind_info_size = static_cast<uint32_t>(fdeInfo.fdeLength);
	_info.extra = static_cast<unw_word_t>(dso_base);
	return true;
	}
	return false;
	}

	template <typename A, typename R>
	bool UnwindCursor<A, R>::getInfoFromDwarfSection(pint_t pc,
	const UnwindInfoSections &sects,
	uint32_t fdeSectionOffsetHint) {
	typename CFI_Parser<A>::FDE_Info fdeInfo;
	typename CFI_Parser<A>::CIE_Info cieInfo;
	bool foundFDE = false;
	bool foundInCache = false;
	// If compact encoding table gave offset into dwarf section, go directly there
	if (fdeSectionOffsetHint != 0) {
	foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
	sects.dwarf_section_length,
	sects.dwarf_section + fdeSectionOffsetHint,
	&fdeInfo, &cieInfo);
	}
	#if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
	if (!foundFDE && (sects.dwarf_index_section != 0)) {
	foundFDE = EHHeaderParser<A>::findFDE(
	_addressSpace, pc, sects.dwarf_index_section,
	(uint32_t)sects.dwarf_index_section_length, &fdeInfo, &cieInfo);
	}
	#endif
	if (!foundFDE) {
	// otherwise, search cache of previously found FDEs.
	pint_t cachedFDE = DwarfFDECache<A>::findFDE(sects.dso_base, pc);
	if (cachedFDE != 0) {
	foundFDE =
	CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
	sects.dwarf_section_length,
	cachedFDE, &fdeInfo, &cieInfo);
	foundInCache = foundFDE;
	}
	}
	if (!foundFDE) {
	// Still not found, do full scan of __eh_frame section.
	foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
	sects.dwarf_section_length, 0,
	&fdeInfo, &cieInfo);
	}
	if (foundFDE) {
	if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, sects.dso_base)) {
	// Add to cache (to make next lookup faster) if we had no hint
	// and there was no index.
	if (!foundInCache && (fdeSectionOffsetHint == 0)) {
	#if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
	if (sects.dwarf_index_section == 0)
	#endif
	DwarfFDECache<A>::add(sects.dso_base, fdeInfo.pcStart, fdeInfo.pcEnd,
	fdeInfo.fdeStart);
	}
	return true;
	}
	}
	//_LIBUNWIND_DEBUG_LOG("can't find/use FDE for pc=0x%llX", (uint64_t)pc);
	return false;
	}
	#endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)


	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
	template <typename A, typename R>
	bool UnwindCursor<A, R>::getInfoFromCompactEncodingSection(pint_t pc,
	const UnwindInfoSections &sects) {
	const bool log = false;
	if (log)
	fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX, mh=0x%llX)\n",
	(uint64_t)pc, (uint64_t)sects.dso_base);

	const UnwindSectionHeader<A> sectionHeader(_addressSpace,
	sects.compact_unwind_section);
	if (sectionHeader.version() != UNWIND_SECTION_VERSION)
	return false;

	// do a binary search of top level index to find page with unwind info
	pint_t targetFunctionOffset = pc - sects.dso_base;
	const UnwindSectionIndexArray<A> topIndex(_addressSpace,
	sects.compact_unwind_section
	+ sectionHeader.indexSectionOffset());
	uint32_t low = 0;
	uint32_t high = sectionHeader.indexCount();
	uint32_t last = high - 1;
	while (low < high) {
	uint32_t mid = (low + high) / 2;
	//if ( log ) fprintf(stderr, "\tmid=%d, low=%d, high=%d, *mid=0x%08X\n",
	//mid, low, high, topIndex.functionOffset(mid));
	if (topIndex.functionOffset(mid) <= targetFunctionOffset) {
	if ((mid == last) \|\|
	(topIndex.functionOffset(mid + 1) > targetFunctionOffset)) {
	low = mid;
	break;
	} else {
	low = mid + 1;
	}
	} else {
	high = mid;
	}
	}
	const uint32_t firstLevelFunctionOffset = topIndex.functionOffset(low);
	const uint32_t firstLevelNextPageFunctionOffset =
	topIndex.functionOffset(low + 1);
	const pint_t secondLevelAddr =
	sects.compact_unwind_section + topIndex.secondLevelPagesSectionOffset(low);
	const pint_t lsdaArrayStartAddr =
	sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low);
	const pint_t lsdaArrayEndAddr =
	sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low+1);
	if (log)
	fprintf(stderr, "\tfirst level search for result index=%d "
	"to secondLevelAddr=0x%llX\n",
	low, (uint64_t) secondLevelAddr);
	// do a binary search of second level page index
	uint32_t encoding = 0;
	pint_t funcStart = 0;
	pint_t funcEnd = 0;
	pint_t lsda = 0;
	pint_t personality = 0;
	uint32_t pageKind = _addressSpace.get32(secondLevelAddr);
	if (pageKind == UNWIND_SECOND_LEVEL_REGULAR) {
	// regular page
	UnwindSectionRegularPageHeader<A> pageHeader(_addressSpace,
	secondLevelAddr);
	UnwindSectionRegularArray<A> pageIndex(
	_addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
	// binary search looks for entry with e where index[e].offset <= pc <
	// index[e+1].offset
	if (log)
	fprintf(stderr, "\tbinary search for targetFunctionOffset=0x%08llX in "
	"regular page starting at secondLevelAddr=0x%llX\n",
	(uint64_t) targetFunctionOffset, (uint64_t) secondLevelAddr);
	low = 0;
	high = pageHeader.entryCount();
	while (low < high) {
	uint32_t mid = (low + high) / 2;
	if (pageIndex.functionOffset(mid) <= targetFunctionOffset) {
	if (mid == (uint32_t)(pageHeader.entryCount() - 1)) {
	// at end of table
	low = mid;
	funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
	break;
	} else if (pageIndex.functionOffset(mid + 1) > targetFunctionOffset) {
	// next is too big, so we found it
	low = mid;
	funcEnd = pageIndex.functionOffset(low + 1) + sects.dso_base;
	break;
	} else {
	low = mid + 1;
	}
	} else {
	high = mid;
	}
	}
	encoding = pageIndex.encoding(low);
	funcStart = pageIndex.functionOffset(low) + sects.dso_base;
	if (pc < funcStart) {
	if (log)
	fprintf(
	stderr,
	"\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
	(uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
	return false;
	}
	if (pc > funcEnd) {
	if (log)
	fprintf(
	stderr,
	"\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
	(uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
	return false;
	}
	} else if (pageKind == UNWIND_SECOND_LEVEL_COMPRESSED) {
	// compressed page
	UnwindSectionCompressedPageHeader<A> pageHeader(_addressSpace,
	secondLevelAddr);
	UnwindSectionCompressedArray<A> pageIndex(
	_addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
	const uint32_t targetFunctionPageOffset =
	(uint32_t)(targetFunctionOffset - firstLevelFunctionOffset);
	// binary search looks for entry with e where index[e].offset <= pc <
	// index[e+1].offset
	if (log)
	fprintf(stderr, "\tbinary search of compressed page starting at "
	"secondLevelAddr=0x%llX\n",
	(uint64_t) secondLevelAddr);
	low = 0;
	last = pageHeader.entryCount() - 1;
	high = pageHeader.entryCount();
	while (low < high) {
	uint32_t mid = (low + high) / 2;
	if (pageIndex.functionOffset(mid) <= targetFunctionPageOffset) {
	if ((mid == last) \|\|
	(pageIndex.functionOffset(mid + 1) > targetFunctionPageOffset)) {
	low = mid;
	break;
	} else {
	low = mid + 1;
	}
	} else {
	high = mid;
	}
	}
	funcStart = pageIndex.functionOffset(low) + firstLevelFunctionOffset
	+ sects.dso_base;
	if (low < last)
	funcEnd =
	pageIndex.functionOffset(low + 1) + firstLevelFunctionOffset
	+ sects.dso_base;
	else
	funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
	if (pc < funcStart) {
	_LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX "
	"not in second level compressed unwind table. "
	"funcStart=0x%llX",
	(uint64_t) pc, (uint64_t) funcStart);
	return false;
	}
	if (pc > funcEnd) {
	_LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX "
	"not in second level compressed unwind table. "
	"funcEnd=0x%llX",
	(uint64_t) pc, (uint64_t) funcEnd);
	return false;
	}
	uint16_t encodingIndex = pageIndex.encodingIndex(low);
	if (encodingIndex < sectionHeader.commonEncodingsArrayCount()) {
	// encoding is in common table in section header
	encoding = _addressSpace.get32(
	sects.compact_unwind_section +
	sectionHeader.commonEncodingsArraySectionOffset() +
	encodingIndex * sizeof(uint32_t));
	} else {
	// encoding is in page specific table
	uint16_t pageEncodingIndex =
	encodingIndex - (uint16_t)sectionHeader.commonEncodingsArrayCount();
	encoding = _addressSpace.get32(secondLevelAddr +
	pageHeader.encodingsPageOffset() +
	pageEncodingIndex * sizeof(uint32_t));
	}
	} else {
	_LIBUNWIND_DEBUG_LOG(
	"malformed __unwind_info at 0x%0llX bad second level page",
	(uint64_t)sects.compact_unwind_section);
	return false;
	}

	// look up LSDA, if encoding says function has one
	if (encoding & UNWIND_HAS_LSDA) {
	UnwindSectionLsdaArray<A> lsdaIndex(_addressSpace, lsdaArrayStartAddr);
	uint32_t funcStartOffset = (uint32_t)(funcStart - sects.dso_base);
	low = 0;
	high = (uint32_t)(lsdaArrayEndAddr - lsdaArrayStartAddr) /
	sizeof(unwind_info_section_header_lsda_index_entry);
	// binary search looks for entry with exact match for functionOffset
	if (log)
	fprintf(stderr,
	"\tbinary search of lsda table for targetFunctionOffset=0x%08X\n",
	funcStartOffset);
	while (low < high) {
	uint32_t mid = (low + high) / 2;
	if (lsdaIndex.functionOffset(mid) == funcStartOffset) {
	lsda = lsdaIndex.lsdaOffset(mid) + sects.dso_base;
	break;
	} else if (lsdaIndex.functionOffset(mid) < funcStartOffset) {
	low = mid + 1;
	} else {
	high = mid;
	}
	}
	if (lsda == 0) {
	_LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with HAS_LSDA bit set for "
	"pc=0x%0llX, but lsda table has no entry",
	encoding, (uint64_t) pc);
	return false;
	}
	}

	// extract personality routine, if encoding says function has one
	uint32_t personalityIndex = (encoding & UNWIND_PERSONALITY_MASK) >>
	(__builtin_ctz(UNWIND_PERSONALITY_MASK));
	if (personalityIndex != 0) {
	--personalityIndex; // change 1-based to zero-based index
	if (personalityIndex >= sectionHeader.personalityArrayCount()) {
	_LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with personality index %d, "
	"but personality table has only %d entries",
	encoding, personalityIndex,
	sectionHeader.personalityArrayCount());
	return false;
	}
	int32_t personalityDelta = (int32_t)_addressSpace.get32(
	sects.compact_unwind_section +
	sectionHeader.personalityArraySectionOffset() +
	personalityIndex * sizeof(uint32_t));
	pint_t personalityPointer = sects.dso_base + (pint_t)personalityDelta;
	personality = _addressSpace.getP(personalityPointer);
	if (log)
	fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
	"personalityDelta=0x%08X, personality=0x%08llX\n",
	(uint64_t) pc, personalityDelta, (uint64_t) personality);
	}

	if (log)
	fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
	"encoding=0x%08X, lsda=0x%08llX for funcStart=0x%llX\n",
	(uint64_t) pc, encoding, (uint64_t) lsda, (uint64_t) funcStart);
	_info.start_ip = funcStart;
	_info.end_ip = funcEnd;
	_info.lsda = lsda;
	_info.handler = personality;
	_info.gp = 0;
	_info.flags = 0;
	_info.format = encoding;
	_info.unwind_info = 0;
	_info.unwind_info_size = 0;
	_info.extra = sects.dso_base;
	return true;
	}
	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)


	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
	template <typename A, typename R>
	bool UnwindCursor<A, R>::getInfoFromSEH(pint_t pc) {
	pint_t base;
	RUNTIME_FUNCTION *unwindEntry = lookUpSEHUnwindInfo(pc, &base);
	if (!unwindEntry) {
	_LIBUNWIND_DEBUG_LOG("\tpc not in table, pc=0x%llX", (uint64_t) pc);
	return false;
	}
	_info.gp = 0;
	_info.flags = 0;
	_info.format = 0;
	_info.unwind_info_size = sizeof(RUNTIME_FUNCTION);
	_info.unwind_info = reinterpret_cast<unw_word_t>(unwindEntry);
	_info.extra = base;
	_info.start_ip = base + unwindEntry->BeginAddress;
	#ifdef _LIBUNWIND_TARGET_X86_64
	_info.end_ip = base + unwindEntry->EndAddress;
	// Only fill in the handler and LSDA if they're stale.
	if (pc != getLastPC()) {
	UNWIND_INFO xdata = reinterpret_cast<UNWIND_INFO >(base + unwindEntry->UnwindData);
	if (xdata->Flags & (UNW_FLAG_EHANDLER\|UNW_FLAG_UHANDLER)) {
	// The personality is given in the UNWIND_INFO itself. The LSDA immediately
	// follows the UNWIND_INFO. (This follows how both Clang and MSVC emit
	// these structures.)
	// N.B. UNWIND_INFO structs are DWORD-aligned.
	uint32_t lastcode = (xdata->CountOfCodes + 1) & ~1;
	const uint32_t handler = reinterpret_cast<uint32_t >(&xdata->UnwindCodes[lastcode]);
	_info.lsda = reinterpret_cast<unw_word_t>(handler+1);
	_dispContext.HandlerData = reinterpret_cast<void *>(_info.lsda);
	_dispContext.LanguageHandler =
	reinterpret_cast<EXCEPTION_ROUTINE >(base + handler);
	if (*handler) {
	_info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
	} else
	_info.handler = 0;
	} else {
	_info.lsda = 0;
	_info.handler = 0;
	}
	}
	#elif defined(_LIBUNWIND_TARGET_AARCH64) \|\| defined(_LIBUNWIND_TARGET_ARM)

	#if defined(_LIBUNWIND_TARGET_AARCH64)
	#define FUNC_LENGTH_UNIT 4
	#define XDATA_TYPE IMAGE_ARM64_RUNTIME_FUNCTION_ENTRY_XDATA
	#else
	#define FUNC_LENGTH_UNIT 2
	#define XDATA_TYPE UNWIND_INFO_ARM
	#endif
	if (unwindEntry->Flag != 0) { // Packed unwind info
	_info.end_ip =
	_info.start_ip + unwindEntry->FunctionLength * FUNC_LENGTH_UNIT;
	// Only fill in the handler and LSDA if they're stale.
	if (pc != getLastPC()) {
	// Packed unwind info doesn't have an exception handler.
	_info.lsda = 0;
	_info.handler = 0;
	}
	} else {
	XDATA_TYPE *xdata =
	reinterpret_cast<XDATA_TYPE *>(base + unwindEntry->UnwindData);
	_info.end_ip = _info.start_ip + xdata->FunctionLength * FUNC_LENGTH_UNIT;
	// Only fill in the handler and LSDA if they're stale.
	if (pc != getLastPC()) {
	if (xdata->ExceptionDataPresent) {
	uint32_t offset = 1; // The main xdata
	uint32_t codeWords = xdata->CodeWords;
	uint32_t epilogScopes = xdata->EpilogCount;
	if (xdata->EpilogCount == 0 && xdata->CodeWords == 0) {
	// The extension word has got the same layout for both ARM and ARM64
	uint32_t extensionWord = reinterpret_cast<uint32_t *>(xdata)[1];
	codeWords = (extensionWord >> 16) & 0xff;
	epilogScopes = extensionWord & 0xffff;
	offset++;
	}
	if (!xdata->EpilogInHeader)
	offset += epilogScopes;
	offset += codeWords;
	uint32_t *exceptionHandlerInfo =
	reinterpret_cast<uint32_t *>(xdata) + offset;
	_dispContext.HandlerData = &exceptionHandlerInfo[1];
	_dispContext.LanguageHandler = reinterpret_cast<EXCEPTION_ROUTINE *>(
	base + exceptionHandlerInfo[0]);
	_info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
	if (exceptionHandlerInfo[0])
	_info.handler =
	reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
	else
	_info.handler = 0;
	} else {
	_info.lsda = 0;
	_info.handler = 0;
	}
	}
	}
	#endif
	setLastPC(pc);
	return true;
	}
	#endif

	#if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
	// Masks for traceback table field xtbtable.
	enum xTBTableMask : uint8_t {
	reservedBit = 0x02, // The traceback table was incorrectly generated if set
	// (see comments in function getInfoFromTBTable().
	ehInfoBit = 0x08 // Exception handling info is present if set
	};

	enum frameType : unw_word_t {
	frameWithXLEHStateTable = 0,
	frameWithEHInfo = 1
	};

	extern "C" {
	typedef _Unwind_Reason_Code __xlcxx_personality_v0_t(int, _Unwind_Action,
	uint64_t,
	_Unwind_Exception *,
	struct _Unwind_Context *);
	}

	static __xlcxx_personality_v0_t *xlcPersonalityV0;
	static RWMutex xlcPersonalityV0InitLock;

	template <typename A, typename R>
	bool UnwindCursor<A, R>::getInfoFromTBTable(pint_t pc, R &registers) {
	uint32_t p = reinterpret_cast<uint32_t >(pc);

	// Keep looking forward until a word of 0 is found. The traceback
	// table starts at the following word.
	while (*p)
	++p;
	tbtable TBTable = reinterpret_cast<tbtable >(p + 1);

	if (_LIBUNWIND_TRACING_UNWINDING) {
	char functionBuf[512];
	const char *functionName = functionBuf;
	unw_word_t offset;
	if (!getFunctionName(functionBuf, sizeof(functionBuf), &offset)) {
	functionName = ".anonymous.";
	}
	_LIBUNWIND_TRACE_UNWINDING("%s: Look up traceback table of func=%s at %p",
	__func__, functionName,
	reinterpret_cast<void *>(TBTable));
	}

	// If the traceback table does not contain necessary info, bypass this frame.
	if (!TBTable->tb.has_tboff)
	return false;

	// Structure tbtable_ext contains important data we are looking for.
	p = reinterpret_cast<uint32_t *>(&TBTable->tb_ext);

	// Skip field parminfo if it exists.
	if (TBTable->tb.fixedparms \|\| TBTable->tb.floatparms)
	++p;

	// p now points to tb_offset, the offset from start of function to TB table.
	unw_word_t start_ip =
	reinterpret_cast<unw_word_t>(TBTable) - *p - sizeof(uint32_t);
	unw_word_t end_ip = reinterpret_cast<unw_word_t>(TBTable);
	++p;

	_LIBUNWIND_TRACE_UNWINDING("start_ip=%p, end_ip=%p\n",
	reinterpret_cast<void *>(start_ip),
	reinterpret_cast<void *>(end_ip));

	// Skip field hand_mask if it exists.
	if (TBTable->tb.int_hndl)
	++p;

	unw_word_t lsda = 0;
	unw_word_t handler = 0;
	unw_word_t flags = frameType::frameWithXLEHStateTable;

	if (TBTable->tb.lang == TB_CPLUSPLUS && TBTable->tb.has_ctl) {
	// State table info is available. The ctl_info field indicates the
	// number of CTL anchors. There should be only one entry for the C++
	// state table.
	assert(*p == 1 && "libunwind: there must be only one ctl_info entry");
	++p;
	// p points to the offset of the state table into the stack.
	pint_t stateTableOffset = *p++;

	int framePointerReg;

	// Skip fields name_len and name if exist.
	if (TBTable->tb.name_present) {
	const uint16_t name_len = (reinterpret_cast<uint16_t >(p));
	p = reinterpret_cast<uint32_t >(reinterpret_cast<char >(p) + name_len +
	sizeof(uint16_t));
	}

	if (TBTable->tb.uses_alloca)
	framePointerReg = (reinterpret_cast<char >(p));
	else
	framePointerReg = 1; // default frame pointer == SP

	_LIBUNWIND_TRACE_UNWINDING(
	"framePointerReg=%d, framePointer=%p, "
	"stateTableOffset=%#lx\n",
	framePointerReg,
	reinterpret_cast<void *>(_registers.getRegister(framePointerReg)),
	stateTableOffset);
	lsda = _registers.getRegister(framePointerReg) + stateTableOffset;

	// Since the traceback table generated by the legacy XLC++ does not
	// provide the location of the personality for the state table,
	// function __xlcxx_personality_v0(), which is the personality for the state
	// table and is exported from libc++abi, is directly assigned as the
	// handler here. When a legacy XLC++ frame is encountered, the symbol
	// is resolved dynamically using dlopen() to avoid a hard dependency of
	// libunwind on libc++abi in cases such as non-C++ applications.

	// Resolve the function pointer to the state table personality if it has
	// not already been done.
	if (xlcPersonalityV0 == NULL) {
	xlcPersonalityV0InitLock.lock();
	if (xlcPersonalityV0 == NULL) {
	// Resolve __xlcxx_personality_v0 using dlopen().
	const char *libcxxabi = "libc++abi.a(libc++abi.so.1)";
	void *libHandle;
	// The AIX dlopen() sets errno to 0 when it is successful, which
	// clobbers the value of errno from the user code. This is an AIX
	// bug because according to POSIX it should not set errno to 0. To
	// workaround before AIX fixes the bug, errno is saved and restored.
	int saveErrno = errno;
	libHandle = dlopen(libcxxabi, RTLD_MEMBER \| RTLD_NOW);
	if (libHandle == NULL) {
	_LIBUNWIND_TRACE_UNWINDING("dlopen() failed with errno=%d\n", errno);
	assert(0 && "dlopen() failed");
	}
	xlcPersonalityV0 = reinterpret_cast<__xlcxx_personality_v0_t *>(
	dlsym(libHandle, "__xlcxx_personality_v0"));
	if (xlcPersonalityV0 == NULL) {
	_LIBUNWIND_TRACE_UNWINDING("dlsym() failed with errno=%d\n", errno);
	dlclose(libHandle);
	assert(0 && "dlsym() failed");
	}
	errno = saveErrno;
	}
	xlcPersonalityV0InitLock.unlock();
	}
	handler = reinterpret_cast<unw_word_t>(xlcPersonalityV0);
	_LIBUNWIND_TRACE_UNWINDING("State table: LSDA=%p, Personality=%p\n",
	reinterpret_cast<void *>(lsda),
	reinterpret_cast<void *>(handler));
	} else if (TBTable->tb.longtbtable) {
	// This frame has the traceback table extension. Possible cases are
	// 1) a C++ frame that has the 'eh_info' structure; 2) a C++ frame that
	// is not EH aware; or, 3) a frame of other languages. We need to figure out
	// if the traceback table extension contains the 'eh_info' structure.
	//
	// We also need to deal with the complexity arising from some XL compiler
	// versions use the wrong ordering of 'longtbtable' and 'has_vec' bits
	// where the 'longtbtable' bit is meant to be the 'has_vec' bit and vice
	// versa. For frames of code generated by those compilers, the 'longtbtable'
	// bit may be set but there isn't really a traceback table extension.
	//
	// In </usr/include/sys/debug.h>, there is the following definition of
	// 'struct tbtable_ext'. It is not really a structure but a dummy to
	// collect the description of optional parts of the traceback table.
	//
	// struct tbtable_ext {
	// ...
	// char alloca_reg; /* Register for alloca automatic storage */
	// struct vec_ext vec_ext; /* Vector extension (if has_vec is set) */
	// unsigned char xtbtable; /* More tbtable fields, if longtbtable is set*/
	// };
	//
	// Depending on how the 'has_vec'/'longtbtable' bit is interpreted, the data
	// following 'alloca_reg' can be treated either as 'struct vec_ext' or
	// 'unsigned char xtbtable'. 'xtbtable' bits are defined in
	// </usr/include/sys/debug.h> as flags. The 7th bit '0x02' is currently
	// unused and should not be set. 'struct vec_ext' is defined in
	// </usr/include/sys/debug.h> as follows:
	//
	// struct vec_ext {
	// unsigned vr_saved:6; /* Number of non-volatile vector regs saved
	// */
	// /* first register saved is assumed to be */
	// /* 32 - vr_saved */
	// unsigned saves_vrsave:1; /* Set if vrsave is saved on the stack */
	// unsigned has_varargs:1;
	// ...
	// };
	//
	// Here, the 7th bit is used as 'saves_vrsave'. To determine whether it
	// is 'struct vec_ext' or 'xtbtable' that follows 'alloca_reg',
	// we checks if the 7th bit is set or not because 'xtbtable' should
	// never have the 7th bit set. The 7th bit of 'xtbtable' will be reserved
	// in the future to make sure the mitigation works. This mitigation
	// is not 100% bullet proof because 'struct vec_ext' may not always have
	// 'saves_vrsave' bit set.
	//
	// 'reservedBit' is defined in enum 'xTBTableMask' above as the mask for
	// checking the 7th bit.

	// p points to field name len.
	uint8_t charPtr = reinterpret_cast<uint8_t >(p);

	// Skip fields name_len and name if they exist.
	if (TBTable->tb.name_present) {
	const uint16_t name_len = (reinterpret_cast<uint16_t >(charPtr));
	charPtr = charPtr + name_len + sizeof(uint16_t);
	}

	// Skip field alloc_reg if it exists.
	if (TBTable->tb.uses_alloca)
	++charPtr;

	// Check traceback table bit has_vec. Skip struct vec_ext if it exists.
	if (TBTable->tb.has_vec)
	// Note struct vec_ext does exist at this point because whether the
	// ordering of longtbtable and has_vec bits is correct or not, both
	// are set.
	charPtr += sizeof(struct vec_ext);

	// charPtr points to field 'xtbtable'. Check if the EH info is available.
	// Also check if the reserved bit of the extended traceback table field
	// 'xtbtable' is set. If it is, the traceback table was incorrectly
	// generated by an XL compiler that uses the wrong ordering of 'longtbtable'
	// and 'has_vec' bits and this is in fact 'struct vec_ext'. So skip the
	// frame.
	if ((*charPtr & xTBTableMask::ehInfoBit) &&
	!(*charPtr & xTBTableMask::reservedBit)) {
	// Mark this frame has the new EH info.
	flags = frameType::frameWithEHInfo;

	// eh_info is available.
	charPtr++;
	// The pointer is 4-byte aligned.
	if (reinterpret_cast<uintptr_t>(charPtr) % 4)
	charPtr += 4 - reinterpret_cast<uintptr_t>(charPtr) % 4;
	uintptr_t *ehInfo =
	reinterpret_cast<uintptr_t >((reinterpret_cast<uintptr_t *>(
	registers.getRegister(2) +
	(reinterpret_cast<uintptr_t >(charPtr)))));

	// ehInfo points to structure en_info. The first member is version.
	// Only version 0 is currently supported.
	assert((reinterpret_cast<uint32_t >(ehInfo)) == 0 &&
	"libunwind: ehInfo version other than 0 is not supported");

	// Increment ehInfo to point to member lsda.
	++ehInfo;
	lsda = *ehInfo++;

	// enInfo now points to member personality.
	handler = *ehInfo;

	_LIBUNWIND_TRACE_UNWINDING("Range table: LSDA=%#lx, Personality=%#lx\n",
	lsda, handler);
	}
	}

	_info.start_ip = start_ip;
	_info.end_ip = end_ip;
	_info.lsda = lsda;
	_info.handler = handler;
	_info.gp = 0;
	_info.flags = flags;
	_info.format = 0;
	_info.unwind_info = reinterpret_cast<unw_word_t>(TBTable);
	_info.unwind_info_size = 0;
	_info.extra = registers.getRegister(2);

	return true;
	}

	// Step back up the stack following the frame back link.
	template <typename A, typename R>
	int UnwindCursor<A, R>::stepWithTBTable(pint_t pc, tbtable *TBTable,
	R &registers, bool &isSignalFrame) {
	if (_LIBUNWIND_TRACING_UNWINDING) {
	char functionBuf[512];
	const char *functionName = functionBuf;
	unw_word_t offset;
	if (!getFunctionName(functionBuf, sizeof(functionBuf), &offset)) {
	functionName = ".anonymous.";
	}
	_LIBUNWIND_TRACE_UNWINDING(
	"%s: Look up traceback table of func=%s at %p, pc=%p, "
	"SP=%p, saves_lr=%d, stores_bc=%d",
	__func__, functionName, reinterpret_cast<void *>(TBTable),
	reinterpret_cast<void *>(pc),
	reinterpret_cast<void *>(registers.getSP()), TBTable->tb.saves_lr,
	TBTable->tb.stores_bc);
	}

	#if defined(__powerpc64__)
	// Instruction to reload TOC register "ld r2,40(r1)"
	const uint32_t loadTOCRegInst = 0xe8410028;
	const int32_t unwPPCF0Index = UNW_PPC64_F0;
	const int32_t unwPPCV0Index = UNW_PPC64_V0;
	#else
	// Instruction to reload TOC register "lwz r2,20(r1)"
	const uint32_t loadTOCRegInst = 0x80410014;
	const int32_t unwPPCF0Index = UNW_PPC_F0;
	const int32_t unwPPCV0Index = UNW_PPC_V0;
	#endif

	// lastStack points to the stack frame of the next routine up.
	pint_t curStack = static_cast<pint_t>(registers.getSP());
	pint_t lastStack = reinterpret_cast<pint_t >(curStack);

	if (lastStack == 0)
	return UNW_STEP_END;

	R newRegisters = registers;

	// If backchain is not stored, use the current stack frame.
	if (!TBTable->tb.stores_bc)
	lastStack = curStack;

	// Return address is the address after call site instruction.
	pint_t returnAddress;

	if (isSignalFrame) {
	_LIBUNWIND_TRACE_UNWINDING("Possible signal handler frame: lastStack=%p",
	reinterpret_cast<void *>(lastStack));

	sigcontext sigContext = reinterpret_cast<sigcontext >(
	reinterpret_cast<char *>(lastStack) + STKMINALIGN);
	returnAddress = sigContext->sc_jmpbuf.jmp_context.iar;

	bool useSTKMIN = false;
	if (returnAddress < 0x10000000) {
	// Try again using STKMIN.
	sigContext = reinterpret_cast<sigcontext *>(
	reinterpret_cast<char *>(lastStack) + STKMIN);
	returnAddress = sigContext->sc_jmpbuf.jmp_context.iar;
	if (returnAddress < 0x10000000) {
	_LIBUNWIND_TRACE_UNWINDING("Bad returnAddress=%p from sigcontext=%p",
	reinterpret_cast<void *>(returnAddress),
	reinterpret_cast<void *>(sigContext));
	return UNW_EBADFRAME;
	}
	useSTKMIN = true;
	}
	_LIBUNWIND_TRACE_UNWINDING("Returning from a signal handler %s: "
	"sigContext=%p, returnAddress=%p. "
	"Seems to be a valid address",
	useSTKMIN ? "STKMIN" : "STKMINALIGN",
	reinterpret_cast<void *>(sigContext),
	reinterpret_cast<void *>(returnAddress));

	// Restore the condition register from sigcontext.
	newRegisters.setCR(sigContext->sc_jmpbuf.jmp_context.cr);

	// Save the LR in sigcontext for stepping up when the function that
	// raised the signal is a leaf function. This LR has the return address
	// to the caller of the leaf function.
	newRegisters.setLR(sigContext->sc_jmpbuf.jmp_context.lr);
	_LIBUNWIND_TRACE_UNWINDING(
	"Save LR=%p from sigcontext",
	reinterpret_cast<void *>(sigContext->sc_jmpbuf.jmp_context.lr));

	// Restore GPRs from sigcontext.
	for (int i = 0; i < 32; ++i)
	newRegisters.setRegister(i, sigContext->sc_jmpbuf.jmp_context.gpr[i]);

	// Restore FPRs from sigcontext.
	for (int i = 0; i < 32; ++i)
	newRegisters.setFloatRegister(i + unwPPCF0Index,
	sigContext->sc_jmpbuf.jmp_context.fpr[i]);

	// Restore vector registers if there is an associated extended context
	// structure.
	if (sigContext->sc_jmpbuf.jmp_context.msr & __EXTCTX) {
	ucontext_t uContext = reinterpret_cast<ucontext_t >(sigContext);
	if (uContext->__extctx->__extctx_magic == __EXTCTX_MAGIC) {
	for (int i = 0; i < 32; ++i)
	newRegisters.setVectorRegister(
	i + unwPPCV0Index, (reinterpret_cast<v128 >(
	&(uContext->__extctx->__vmx.__vr[i]))));
	}
	}
	} else {
	// Step up a normal frame.

	if (!TBTable->tb.saves_lr && registers.getLR()) {
	// This case should only occur if we were called from a signal handler
	// and the signal occurred in a function that doesn't save the LR.
	returnAddress = static_cast<pint_t>(registers.getLR());
	_LIBUNWIND_TRACE_UNWINDING("Use saved LR=%p",
	reinterpret_cast<void *>(returnAddress));
	} else {
	// Otherwise, use the LR value in the stack link area.
	returnAddress = reinterpret_cast<pint_t *>(lastStack)[2];
	}

	// Reset LR in the current context.
	newRegisters.setLR(static_cast<uintptr_t>(NULL));

	_LIBUNWIND_TRACE_UNWINDING(
	"Extract info from lastStack=%p, returnAddress=%p",
	reinterpret_cast<void *>(lastStack),
	reinterpret_cast<void *>(returnAddress));
	_LIBUNWIND_TRACE_UNWINDING("fpr_regs=%d, gpr_regs=%d, saves_cr=%d",
	TBTable->tb.fpr_saved, TBTable->tb.gpr_saved,
	TBTable->tb.saves_cr);

	// Restore FP registers.
	char ptrToRegs = reinterpret_cast<char >(lastStack);
	double FPRegs = reinterpret_cast<double >(
	ptrToRegs - (TBTable->tb.fpr_saved * sizeof(double)));
	for (int i = 0; i < TBTable->tb.fpr_saved; ++i)
	newRegisters.setFloatRegister(
	32 - TBTable->tb.fpr_saved + i + unwPPCF0Index, FPRegs[i]);

	// Restore GP registers.
	ptrToRegs = reinterpret_cast<char *>(FPRegs);
	uintptr_t GPRegs = reinterpret_cast<uintptr_t >(
	ptrToRegs - (TBTable->tb.gpr_saved * sizeof(uintptr_t)));
	for (int i = 0; i < TBTable->tb.gpr_saved; ++i)
	newRegisters.setRegister(32 - TBTable->tb.gpr_saved + i, GPRegs[i]);

	// Restore Vector registers.
	ptrToRegs = reinterpret_cast<char *>(GPRegs);

	// Restore vector registers only if this is a Clang frame. Also
	// check if traceback table bit has_vec is set. If it is, structure
	// vec_ext is available.
	if (_info.flags == frameType::frameWithEHInfo && TBTable->tb.has_vec) {

	// Get to the vec_ext structure to check if vector registers are saved.
	uint32_t p = reinterpret_cast<uint32_t >(&TBTable->tb_ext);

	// Skip field parminfo if exists.
	if (TBTable->tb.fixedparms \|\| TBTable->tb.floatparms)
	++p;

	// Skip field tb_offset if exists.
	if (TBTable->tb.has_tboff)
	++p;

	// Skip field hand_mask if exists.
	if (TBTable->tb.int_hndl)
	++p;

	// Skip fields ctl_info and ctl_info_disp if exist.
	if (TBTable->tb.has_ctl) {
	// Skip field ctl_info.
	++p;
	// Skip field ctl_info_disp.
	++p;
	}

	// Skip fields name_len and name if exist.
	// p is supposed to point to field name_len now.
	uint8_t charPtr = reinterpret_cast<uint8_t >(p);
	if (TBTable->tb.name_present) {
	const uint16_t name_len = (reinterpret_cast<uint16_t >(charPtr));
	charPtr = charPtr + name_len + sizeof(uint16_t);
	}

	// Skip field alloc_reg if it exists.
	if (TBTable->tb.uses_alloca)
	++charPtr;

	struct vec_ext vec_ext = reinterpret_cast<struct vec_ext >(charPtr);

	_LIBUNWIND_TRACE_UNWINDING("vr_saved=%d", vec_ext->vr_saved);

	// Restore vector register(s) if saved on the stack.
	if (vec_ext->vr_saved) {
	// Saved vector registers are 16-byte aligned.
	if (reinterpret_cast<uintptr_t>(ptrToRegs) % 16)
	ptrToRegs -= reinterpret_cast<uintptr_t>(ptrToRegs) % 16;
	v128 VecRegs = reinterpret_cast<v128 >(ptrToRegs - vec_ext->vr_saved *
	sizeof(v128));
	for (int i = 0; i < vec_ext->vr_saved; ++i) {
	newRegisters.setVectorRegister(
	32 - vec_ext->vr_saved + i + unwPPCV0Index, VecRegs[i]);
	}
	}
	}
	if (TBTable->tb.saves_cr) {
	// Get the saved condition register. The condition register is only
	// a single word.
	newRegisters.setCR(
	(reinterpret_cast<uint32_t >(lastStack + sizeof(uintptr_t))));
	}

	// Restore the SP.
	newRegisters.setSP(lastStack);

	// The first instruction after return.
	uint32_t firstInstruction = (reinterpret_cast<uint32_t >(returnAddress));

	// Do we need to set the TOC register?
	_LIBUNWIND_TRACE_UNWINDING(
	"Current gpr2=%p",
	reinterpret_cast<void *>(newRegisters.getRegister(2)));
	if (firstInstruction == loadTOCRegInst) {
	_LIBUNWIND_TRACE_UNWINDING(
	"Set gpr2=%p from frame",
	reinterpret_cast<void >(reinterpret_cast<pint_t >(lastStack)[5]));
	newRegisters.setRegister(2, reinterpret_cast<pint_t *>(lastStack)[5]);
	}
	}
	_LIBUNWIND_TRACE_UNWINDING("lastStack=%p, returnAddress=%p, pc=%p\n",
	reinterpret_cast<void *>(lastStack),
	reinterpret_cast<void *>(returnAddress),
	reinterpret_cast<void *>(pc));

	// The return address is the address after call site instruction, so
	// setting IP to that simulates a return.
	newRegisters.setIP(reinterpret_cast<uintptr_t>(returnAddress));

	// Simulate the step by replacing the register set with the new ones.
	registers = newRegisters;

	// Check if the next frame is a signal frame.
	pint_t nextStack = (reinterpret_cast<pint_t >(registers.getSP()));

	// Return address is the address after call site instruction.
	pint_t nextReturnAddress = reinterpret_cast<pint_t *>(nextStack)[2];

	if (nextReturnAddress > 0x01 && nextReturnAddress < 0x10000) {
	_LIBUNWIND_TRACE_UNWINDING("The next is a signal handler frame: "
	"nextStack=%p, next return address=%p\n",
	reinterpret_cast<void *>(nextStack),
	reinterpret_cast<void *>(nextReturnAddress));
	isSignalFrame = true;
	} else {
	isSignalFrame = false;
	}
	return UNW_STEP_SUCCESS;
	}
	#endif // defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)

	template <typename A, typename R>
	void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
	defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
	_isSigReturn = false;
	#endif

	pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
	#if defined(_LIBUNWIND_ARM_EHABI)
	// Remove the thumb bit so the IP represents the actual instruction address.
	// This matches the behaviour of _Unwind_GetIP on arm.
	pc &= (pint_t)~0x1;
	#endif

	// Exit early if at the top of the stack.
	if (pc == 0) {
	_unwindInfoMissing = true;
	return;
	}

	// If the last line of a function is a "throw" the compiler sometimes
	// emits no instructions after the call to __cxa_throw. This means
	// the return address is actually the start of the next function.
	// To disambiguate this, back up the pc when we know it is a return
	// address.
	if (isReturnAddress)
	#if defined(_AIX)
	// PC needs to be a 4-byte aligned address to be able to look for a
	// word of 0 that indicates the start of the traceback table at the end
	// of a function on AIX.
	pc -= 4;
	#else
	--pc;
	#endif

	#if !(defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)) && \
	!defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
	// In case of this is frame of signal handler, the IP saved in the signal
	// handler points to first non-executed instruction, while FDE/CIE expects IP
	// to be after the first non-executed instruction.
	if (_isSignalFrame)
	++pc;
	#endif

	// Ask address space object to find unwind sections for this pc.
	UnwindInfoSections sects;
	if (_addressSpace.findUnwindSections(pc, sects)) {
	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
	// If there is a compact unwind encoding table, look there first.
	if (sects.compact_unwind_section != 0) {
	if (this->getInfoFromCompactEncodingSection(pc, sects)) {
	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
	// Found info in table, done unless encoding says to use dwarf.
	uint32_t dwarfOffset;
	if ((sects.dwarf_section != 0) && compactSaysUseDwarf(&dwarfOffset)) {
	if (this->getInfoFromDwarfSection(pc, sects, dwarfOffset)) {
	// found info in dwarf, done
	return;
	}
	}
	#endif
	// If unwind table has entry, but entry says there is no unwind info,
	// record that we have no unwind info.
	if (_info.format == 0)
	_unwindInfoMissing = true;
	return;
	}
	}
	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)

	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
	// If there is SEH unwind info, look there next.
	if (this->getInfoFromSEH(pc))
	return;
	#endif

	#if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
	// If there is unwind info in the traceback table, look there next.
	if (this->getInfoFromTBTable(pc, _registers))
	return;
	#endif

	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
	// If there is dwarf unwind info, look there next.
	if (sects.dwarf_section != 0) {
	if (this->getInfoFromDwarfSection(pc, sects)) {
	// found info in dwarf, done
	return;
	}
	}
	#endif

	#if defined(_LIBUNWIND_ARM_EHABI)
	// If there is ARM EHABI unwind info, look there next.
	if (sects.arm_section != 0 && this->getInfoFromEHABISection(pc, sects))
	return;
	#endif
	}

	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
	// There is no static unwind info for this pc. Look to see if an FDE was
	// dynamically registered for it.
	pint_t cachedFDE = DwarfFDECache<A>::findFDE(DwarfFDECache<A>::kSearchAll,
	pc);
	if (cachedFDE != 0) {
	typename CFI_Parser<A>::FDE_Info fdeInfo;
	typename CFI_Parser<A>::CIE_Info cieInfo;
	if (!CFI_Parser<A>::decodeFDE(_addressSpace, cachedFDE, &fdeInfo, &cieInfo))
	if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, 0))
	return;
	}

	// Lastly, ask AddressSpace object about platform specific ways to locate
	// other FDEs.
	pint_t fde;
	if (_addressSpace.findOtherFDE(pc, fde)) {
	typename CFI_Parser<A>::FDE_Info fdeInfo;
	typename CFI_Parser<A>::CIE_Info cieInfo;
	if (!CFI_Parser<A>::decodeFDE(_addressSpace, fde, &fdeInfo, &cieInfo)) {
	// Double check this FDE is for a function that includes the pc.
	if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd))
	if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, 0))
	return;
	}
	}
	#endif // #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)

	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
	defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
	if (setInfoForSigReturn())
	return;
	#endif

	// no unwind info, flag that we can't reliably unwind
	_unwindInfoMissing = true;
	}

	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
	defined(_LIBUNWIND_TARGET_AARCH64)
	template <typename A, typename R>
	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_arm64 &) {
	// Look for the sigreturn trampoline. The trampoline's body is two
	// specific instructions (see below). Typically the trampoline comes from the
	// vDSO[1] (i.e. the __kernel_rt_sigreturn function). A libc might provide its
	// own restorer function, though, or user-mode QEMU might write a trampoline
	// onto the stack.
	//
	// This special code path is a fallback that is only used if the trampoline
	// lacks proper (e.g. DWARF) unwind info. On AArch64, a new DWARF register
	// constant for the PC needs to be defined before DWARF can handle a signal
	// trampoline. This code may segfault if the target PC is unreadable, e.g.:
	// - The PC points at a function compiled without unwind info, and which is
	// part of an execute-only mapping (e.g. using -Wl,--execute-only).
	// - The PC is invalid and happens to point to unreadable or unmapped memory.
	//
	// [1] https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/vdso/sigreturn.S
	const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
	// The PC might contain an invalid address if the unwind info is bad, so
	// directly accessing it could cause a SIGSEGV.
	if (!isReadableAddr(pc))
	return false;
	auto instructions = reinterpret_cast<const uint32_t >(pc);
	// Look for instructions: mov x8, #0x8b; svc #0x0
	if (instructions[0] != 0xd2801168 \|\| instructions[1] != 0xd4000001)
	return false;

	_info = {};
	_info.start_ip = pc;
	_info.end_ip = pc + 4;
	_isSigReturn = true;
	return true;
	}

	template <typename A, typename R>
	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_arm64 &) {
	// In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
	// - 128-byte siginfo struct
	// - ucontext struct:
	// - 8-byte long (uc_flags)
	// - 8-byte pointer (uc_link)
	// - 24-byte stack_t
	// - 128-byte signal set
	// - 8 bytes of padding because sigcontext has 16-byte alignment
	// - sigcontext/mcontext_t
	// [1] https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/signal.c
	const pint_t kOffsetSpToSigcontext = (128 + 8 + 8 + 24 + 128 + 8); // 304

	// Offsets from sigcontext to each register.
	const pint_t kOffsetGprs = 8; // offset to "__u64 regs[31]" field
	const pint_t kOffsetSp = 256; // offset to "__u64 sp" field
	const pint_t kOffsetPc = 264; // offset to "__u64 pc" field

	pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;

	for (int i = 0; i <= 30; ++i) {
	uint64_t value = _addressSpace.get64(sigctx + kOffsetGprs +
	static_cast<pint_t>(i * 8));
	_registers.setRegister(UNW_AARCH64_X0 + i, value);
	}
	_registers.setSP(_addressSpace.get64(sigctx + kOffsetSp));
	_registers.setIP(_addressSpace.get64(sigctx + kOffsetPc));
	_isSignalFrame = true;
	return UNW_STEP_SUCCESS;
	}
	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
	// defined(_LIBUNWIND_TARGET_AARCH64)

	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
	defined(_LIBUNWIND_TARGET_LOONGARCH)
	template <typename A, typename R>
	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_loongarch &) {
	const pint_t pc = static_cast<pint_t>(getReg(UNW_REG_IP));
	// The PC might contain an invalid address if the unwind info is bad, so
	// directly accessing it could cause a SIGSEGV.
	if (!isReadableAddr(pc))
	return false;
	const auto instructions = reinterpret_cast<const uint32_t >(pc);
	// Look for the two instructions used in the sigreturn trampoline
	// __vdso_rt_sigreturn:
	//
	// 0x03822c0b li a7,0x8b
	// 0x002b0000 syscall 0
	if (instructions[0] != 0x03822c0b \|\| instructions[1] != 0x002b0000)
	return false;

	_info = {};
	_info.start_ip = pc;
	_info.end_ip = pc + 4;
	_isSigReturn = true;
	return true;
	}

	template <typename A, typename R>
	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_loongarch &) {
	// In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
	// - 128-byte siginfo struct
	// - ucontext_t struct:
	// - 8-byte long (__uc_flags)
	// - 8-byte pointer (*uc_link)
	// - 24-byte uc_stack
	// - 8-byte uc_sigmask
	// - 120-byte of padding to allow sigset_t to be expanded in the future
	// - 8 bytes of padding because sigcontext has 16-byte alignment
	// - struct sigcontext uc_mcontext
	// [1]
	// https://github.com/torvalds/linux/blob/master/arch/loongarch/kernel/signal.c
	const pint_t kOffsetSpToSigcontext = 128 + 8 + 8 + 24 + 8 + 128;

	const pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;
	_registers.setIP(_addressSpace.get64(sigctx));
	for (int i = UNW_LOONGARCH_R1; i <= UNW_LOONGARCH_R31; ++i) {
	// skip R0
	uint64_t value =
	_addressSpace.get64(sigctx + static_cast<pint_t>((i + 1) * 8));
	_registers.setRegister(i, value);
	}
	_isSignalFrame = true;
	return UNW_STEP_SUCCESS;
	}
	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
	// defined(_LIBUNWIND_TARGET_LOONGARCH)

	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
	defined(_LIBUNWIND_TARGET_RISCV)
	template <typename A, typename R>
	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_riscv &) {
	const pint_t pc = static_cast<pint_t>(getReg(UNW_REG_IP));
	// The PC might contain an invalid address if the unwind info is bad, so
	// directly accessing it could cause a SIGSEGV.
	if (!isReadableAddr(pc))
	return false;
	const auto instructions = reinterpret_cast<const uint32_t >(pc);
	// Look for the two instructions used in the sigreturn trampoline
	// __vdso_rt_sigreturn:
	//
	// 0x08b00893 li a7,0x8b
	// 0x00000073 ecall
	if (instructions[0] != 0x08b00893 \|\| instructions[1] != 0x00000073)
	return false;

	_info = {};
	_info.start_ip = pc;
	_info.end_ip = pc + 4;
	_isSigReturn = true;
	return true;
	}

	template <typename A, typename R>
	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_riscv &) {
	// In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
	// - 128-byte siginfo struct
	// - ucontext_t struct:
	// - 8-byte long (__uc_flags)
	// - 8-byte pointer (*uc_link)
	// - 24-byte uc_stack
	// - 8-byte uc_sigmask
	// - 120-byte of padding to allow sigset_t to be expanded in the future
	// - 8 bytes of padding because sigcontext has 16-byte alignment
	// - struct sigcontext uc_mcontext
	// [1]
	// https://github.com/torvalds/linux/blob/master/arch/riscv/kernel/signal.c
	const pint_t kOffsetSpToSigcontext = 128 + 8 + 8 + 24 + 8 + 128;

	const pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;
	_registers.setIP(_addressSpace.get64(sigctx));
	for (int i = UNW_RISCV_X1; i <= UNW_RISCV_X31; ++i) {
	uint64_t value = _addressSpace.get64(sigctx + static_cast<pint_t>(i * 8));
	_registers.setRegister(i, value);
	}
	_isSignalFrame = true;
	return UNW_STEP_SUCCESS;
	}
	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
	// defined(_LIBUNWIND_TARGET_RISCV)

	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
	defined(_LIBUNWIND_TARGET_S390X)
	template <typename A, typename R>
	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_s390x &) {
	// Look for the sigreturn trampoline. The trampoline's body is a
	// specific instruction (see below). Typically the trampoline comes from the
	// vDSO (i.e. the __kernel_[rt_]sigreturn function). A libc might provide its
	// own restorer function, though, or user-mode QEMU might write a trampoline
	// onto the stack.
	const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
	// The PC might contain an invalid address if the unwind info is bad, so
	// directly accessing it could cause a SIGSEGV.
	if (!isReadableAddr(pc))
	return false;
	const auto inst = reinterpret_cast<const uint16_t >(pc);
	if (inst == 0x0a77 \|\| inst == 0x0aad) {
	_info = {};
	_info.start_ip = pc;
	_info.end_ip = pc + 2;
	_isSigReturn = true;
	return true;
	}
	return false;
	}

	template <typename A, typename R>
	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_s390x &) {
	// Determine current SP.
	const pint_t sp = static_cast<pint_t>(this->getReg(UNW_REG_SP));
	// According to the s390x ABI, the CFA is at (incoming) SP + 160.
	const pint_t cfa = sp + 160;

	// Determine current PC and instruction there (this must be either
	// a "svc __NR_sigreturn" or "svc __NR_rt_sigreturn").
	const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
	const uint16_t inst = _addressSpace.get16(pc);

	// Find the addresses of the signo and sigcontext in the frame.
	pint_t pSigctx = 0;
	pint_t pSigno = 0;

	// "svc __NR_sigreturn" uses a non-RT signal trampoline frame.
	if (inst == 0x0a77) {
	// Layout of a non-RT signal trampoline frame, starting at the CFA:
	// - 8-byte signal mask
	// - 8-byte pointer to sigcontext, followed by signo
	// - 4-byte signo
	pSigctx = _addressSpace.get64(cfa + 8);
	pSigno = pSigctx + 344;
	}

	// "svc __NR_rt_sigreturn" uses a RT signal trampoline frame.
	if (inst == 0x0aad) {
	// Layout of a RT signal trampoline frame, starting at the CFA:
	// - 8-byte retcode (+ alignment)
	// - 128-byte siginfo struct (starts with signo)
	// - ucontext struct:
	// - 8-byte long (uc_flags)
	// - 8-byte pointer (uc_link)
	// - 24-byte stack_t
	// - 8 bytes of padding because sigcontext has 16-byte alignment
	// - sigcontext/mcontext_t
	pSigctx = cfa + 8 + 128 + 8 + 8 + 24 + 8;
	pSigno = cfa + 8;
	}

	assert(pSigctx != 0);
	assert(pSigno != 0);

	// Offsets from sigcontext to each register.
	const pint_t kOffsetPc = 8;
	const pint_t kOffsetGprs = 16;
	const pint_t kOffsetFprs = 216;

	// Restore all registers.
	for (int i = 0; i < 16; ++i) {
	uint64_t value = _addressSpace.get64(pSigctx + kOffsetGprs +
	static_cast<pint_t>(i * 8));
	_registers.setRegister(UNW_S390X_R0 + i, value);
	}
	for (int i = 0; i < 16; ++i) {
	static const int fpr[16] = {
	UNW_S390X_F0, UNW_S390X_F1, UNW_S390X_F2, UNW_S390X_F3,
	UNW_S390X_F4, UNW_S390X_F5, UNW_S390X_F6, UNW_S390X_F7,
	UNW_S390X_F8, UNW_S390X_F9, UNW_S390X_F10, UNW_S390X_F11,
	UNW_S390X_F12, UNW_S390X_F13, UNW_S390X_F14, UNW_S390X_F15
	};
	double value = _addressSpace.getDouble(pSigctx + kOffsetFprs +
	static_cast<pint_t>(i * 8));
	_registers.setFloatRegister(fpr[i], value);
	}
	_registers.setIP(_addressSpace.get64(pSigctx + kOffsetPc));

	// SIGILL, SIGFPE and SIGTRAP are delivered with psw_addr
	// after the faulting instruction rather than before it.
	// Do not set _isSignalFrame in that case.
	uint32_t signo = _addressSpace.get32(pSigno);
	_isSignalFrame = (signo != 4 && signo != 5 && signo != 8);

	return UNW_STEP_SUCCESS;
	}
	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
	// defined(_LIBUNWIND_TARGET_S390X)

	#if defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
	template <typename A, typename R>
	bool UnwindCursor<A, R>::setInfoForSigReturn() {
	Dl_info dlinfo;
	const auto isSignalHandler = [&](pint_t addr) {
	if (!dladdr(reinterpret_cast<void *>(addr), &dlinfo))
	return false;
	if (strcmp(dlinfo.dli_fname, "commpage"))
	return false;
	if (dlinfo.dli_sname == NULL \|\|
	strcmp(dlinfo.dli_sname, "commpage_signal_handler"))
	return false;
	return true;
	};

	pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
	if (!isSignalHandler(pc))
	return false;

	pint_t start = reinterpret_cast<pint_t>(dlinfo.dli_saddr);

	static size_t signalHandlerSize = 0;
	if (signalHandlerSize == 0) {
	size_t boundLow = 0;
	size_t boundHigh = static_cast<size_t>(-1);

	area_info areaInfo;
	if (get_area_info(area_for(dlinfo.dli_saddr), &areaInfo) == B_OK)
	boundHigh = areaInfo.size;

	while (boundLow < boundHigh) {
	size_t boundMid = boundLow + ((boundHigh - boundLow) / 2);
	pint_t test = start + boundMid;
	if (test >= start && isSignalHandler(test))
	boundLow = boundMid + 1;
	else
	boundHigh = boundMid;
	}

	signalHandlerSize = boundHigh;
	}

	_info = {};
	_info.start_ip = start;
	_info.end_ip = start + signalHandlerSize;
	_isSigReturn = true;

	return true;
	}

	template <typename A, typename R>
	int UnwindCursor<A, R>::stepThroughSigReturn() {
	_isSignalFrame = true;

	#if defined(_LIBUNWIND_TARGET_X86_64)
	// Layout of the stack before function call:
	// - signal_frame_data
	// + siginfo_t (public struct, fairly stable)
	// + ucontext_t (public struct, fairly stable)
	// - mcontext_t -> Offset 0x70, this is what we want.
	// - frame->ip (8 bytes)
	// - frame->bp (8 bytes). Not written by the kernel,
	// but the signal handler has a "push %rbp" instruction.
	pint_t bp = this->getReg(UNW_X86_64_RBP);
	vregs regs = (vregs )(bp + 0x70);

	_registers.setRegister(UNW_REG_IP, regs->rip);
	_registers.setRegister(UNW_REG_SP, regs->rsp);
	_registers.setRegister(UNW_X86_64_RAX, regs->rax);
	_registers.setRegister(UNW_X86_64_RDX, regs->rdx);
	_registers.setRegister(UNW_X86_64_RCX, regs->rcx);
	_registers.setRegister(UNW_X86_64_RBX, regs->rbx);
	_registers.setRegister(UNW_X86_64_RSI, regs->rsi);
	_registers.setRegister(UNW_X86_64_RDI, regs->rdi);
	_registers.setRegister(UNW_X86_64_RBP, regs->rbp);
	_registers.setRegister(UNW_X86_64_R8, regs->r8);
	_registers.setRegister(UNW_X86_64_R9, regs->r9);
	_registers.setRegister(UNW_X86_64_R10, regs->r10);
	_registers.setRegister(UNW_X86_64_R11, regs->r11);
	_registers.setRegister(UNW_X86_64_R12, regs->r12);
	_registers.setRegister(UNW_X86_64_R13, regs->r13);
	_registers.setRegister(UNW_X86_64_R14, regs->r14);
	_registers.setRegister(UNW_X86_64_R15, regs->r15);
	// TODO: XMM
	#endif // defined(_LIBUNWIND_TARGET_X86_64)

	return UNW_STEP_SUCCESS;
	}
	#endif // defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)

	template <typename A, typename R> int UnwindCursor<A, R>::step(bool stage2) {
	(void)stage2;
	// Bottom of stack is defined is when unwind info cannot be found.
	if (_unwindInfoMissing)
	return UNW_STEP_END;

	// Use unwinding info to modify register set as if function returned.
	int result;
	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
	defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
	if (_isSigReturn) {
	result = this->stepThroughSigReturn();
	} else
	#endif
	{
	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
	result = this->stepWithCompactEncoding(stage2);
	#elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
	result = this->stepWithSEHData();
	#elif defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
	result = this->stepWithTBTableData();
	#elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
	result = this->stepWithDwarfFDE(stage2);
	#elif defined(_LIBUNWIND_ARM_EHABI)
	result = this->stepWithEHABI();
	#else
	#error Need _LIBUNWIND_SUPPORT_COMPACT_UNWIND or \
	_LIBUNWIND_SUPPORT_SEH_UNWIND or \
	_LIBUNWIND_SUPPORT_DWARF_UNWIND or \
	_LIBUNWIND_ARM_EHABI
	#endif
	}

	// update info based on new PC
	if (result == UNW_STEP_SUCCESS) {
	this->setInfoBasedOnIPRegister(true);
	if (_unwindInfoMissing)
	return UNW_STEP_END;
	}

	return result;
	}

	template <typename A, typename R>
	void UnwindCursor<A, R>::getInfo(unw_proc_info_t *info) {
	if (_unwindInfoMissing)
	memset(info, 0, sizeof(*info));
	else
	*info = _info;
	}

	template <typename A, typename R>
	bool UnwindCursor<A, R>::getFunctionName(char *buf, size_t bufLen,
	unw_word_t *offset) {
	return _addressSpace.findFunctionName((pint_t)this->getReg(UNW_REG_IP),
	buf, bufLen, offset);
	}

	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
	template <typename A, typename R>
	bool UnwindCursor<A, R>::isReadableAddr(const pint_t addr) const {
	// We use SYS_rt_sigprocmask, inspired by Abseil's AddressIsReadable.

	const auto sigsetAddr = reinterpret_cast<sigset_t *>(addr);
	// We have to check that addr is nullptr because sigprocmask allows that
	// as an argument without failure.
	if (!sigsetAddr)
	return false;
	const auto saveErrno = errno;
	// We MUST use a raw syscall here, as wrappers may try to access
	// sigsetAddr which may cause a SIGSEGV. A raw syscall however is
	// safe. Additionally, we need to pass the kernel_sigset_size, which is
	// different from libc sizeof(sigset_t). For the majority of architectures,
	// it's 64 bits (_NSIG), and libc NSIG is _NSIG + 1.
	const auto kernelSigsetSize = NSIG / 8;
	[[maybe_unused]] const int Result = syscall(
	SYS_rt_sigprocmask, /how=/~0, sigsetAddr, nullptr, kernelSigsetSize);
	// Because our "how" is invalid, this syscall should always fail, and our
	// errno should always be EINVAL or an EFAULT. This relies on the Linux
	// kernel to check copy_from_user before checking if the "how" argument is
	// invalid.
	assert(Result == -1);
	assert(errno == EFAULT \|\| errno == EINVAL);
	const auto readable = errno != EFAULT;
	errno = saveErrno;
	return readable;
	}
	#endif

	#if defined(_LIBUNWIND_USE_CET) \|\| defined(_LIBUNWIND_USE_GCS)
	extern "C" void __libunwind_shstk_get_registers(unw_cursor_t cursor) {
	AbstractUnwindCursor co = (AbstractUnwindCursor )cursor;
	return co->get_registers();
	}
	#endif
	} // namespace libunwind

	#endif // __UNWINDCURSOR_HPP__

Xet Storage Details

Size:: 116 kB
Xet hash:: f177209c8dbe6ef42ca8018b3970eb188f20c4629c101b59f007d9fd185cbc96

Xet efficiently stores files, intelligently splitting them into unique chunks and accelerating uploads and downloads. More info.