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//===------------------------------- unwind.h -----------------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// C++ ABI Level 1 ABI documented at:
#ifndef __UNWIND_H__
#define __UNWIND_H__
#include <__libunwind_config.h>
#include <stdint.h>
#include <stddef.h>
#if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__) && defined(_WIN32)
#include <windows.h>
#include <ntverp.h>
#if defined(__APPLE__)
#define LIBUNWIND_UNAVAIL __attribute__ (( unavailable ))
typedef enum {
_URC_OK = 0,
} _Unwind_Reason_Code;
typedef enum {
_UA_END_OF_STACK = 16 // gcc extension to C++ ABI
} _Unwind_Action;
typedef struct _Unwind_Context _Unwind_Context; // opaque
typedef uint32_t _Unwind_State;
static const _Unwind_State _US_VIRTUAL_UNWIND_FRAME = 0;
static const _Unwind_State _US_UNWIND_FRAME_STARTING = 1;
static const _Unwind_State _US_UNWIND_FRAME_RESUME = 2;
static const _Unwind_State _US_ACTION_MASK = 3;
/* Undocumented flag for force unwinding. */
static const _Unwind_State _US_FORCE_UNWIND = 8;
typedef uint32_t _Unwind_EHT_Header;
struct _Unwind_Control_Block;
typedef struct _Unwind_Control_Block _Unwind_Control_Block;
typedef struct _Unwind_Control_Block _Unwind_Exception; /* Alias */
struct _Unwind_Control_Block {
uint64_t exception_class;
void (*exception_cleanup)(_Unwind_Reason_Code, _Unwind_Control_Block*);
/* Unwinder cache, private fields for the unwinder's use */
struct {
uint32_t reserved1; /* init reserved1 to 0, then don't touch */
uint32_t reserved2;
uint32_t reserved3;
uint32_t reserved4;
uint32_t reserved5;
} unwinder_cache;
/* Propagation barrier cache (valid after phase 1): */
struct {
uint32_t sp;
uint32_t bitpattern[5];
} barrier_cache;
/* Cleanup cache (preserved over cleanup): */
struct {
uint32_t bitpattern[4];
} cleanup_cache;
/* Pr cache (for pr's benefit): */
struct {
uint32_t fnstart; /* function start address */
_Unwind_EHT_Header* ehtp; /* pointer to EHT entry header word */
uint32_t additional;
uint32_t reserved1;
} pr_cache;
long long int :0; /* Enforce the 8-byte alignment */
} __attribute__((__aligned__(8)));
typedef _Unwind_Reason_Code (*_Unwind_Stop_Fn)
(_Unwind_State state,
_Unwind_Exception* exceptionObject,
struct _Unwind_Context* context);
typedef _Unwind_Reason_Code (*_Unwind_Personality_Fn)(
_Unwind_State state, _Unwind_Exception *exceptionObject,
struct _Unwind_Context *context);
struct _Unwind_Context; // opaque
struct _Unwind_Exception; // forward declaration
typedef struct _Unwind_Exception _Unwind_Exception;
struct _Unwind_Exception {
uint64_t exception_class;
void (*exception_cleanup)(_Unwind_Reason_Code reason,
_Unwind_Exception *exc);
#if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)
uintptr_t private_[6];
uintptr_t private_1; // non-zero means forced unwind
uintptr_t private_2; // holds sp that phase1 found for phase2 to use
#if __SIZEOF_POINTER__ == 4
// The implementation of _Unwind_Exception uses an attribute mode on the
// above fields which has the side effect of causing this whole struct to
// round up to 32 bytes in size (48 with SEH). To be more explicit, we add
// pad fields added for binary compatibility.
uint32_t reserved[3];
// The Itanium ABI requires that _Unwind_Exception objects are "double-word
// aligned". GCC has interpreted this to mean "use the maximum useful
// alignment for the target"; so do we.
} __attribute__((__aligned__));
typedef _Unwind_Reason_Code (*_Unwind_Stop_Fn)
(int version,
_Unwind_Action actions,
uint64_t exceptionClass,
_Unwind_Exception* exceptionObject,
struct _Unwind_Context* context,
void* stop_parameter );
typedef _Unwind_Reason_Code (*_Unwind_Personality_Fn)(
int version, _Unwind_Action actions, uint64_t exceptionClass,
_Unwind_Exception *exceptionObject, struct _Unwind_Context *context);
#ifdef __cplusplus
extern "C" {
// The following are the base functions documented by the C++ ABI
extern _Unwind_Reason_Code
_Unwind_SjLj_RaiseException(_Unwind_Exception *exception_object);
extern void _Unwind_SjLj_Resume(_Unwind_Exception *exception_object);
extern _Unwind_Reason_Code
_Unwind_RaiseException(_Unwind_Exception *exception_object);
extern void _Unwind_Resume(_Unwind_Exception *exception_object);
extern void _Unwind_DeleteException(_Unwind_Exception *exception_object);
typedef enum {
_UVRSC_CORE = 0, /* integer register */
_UVRSC_VFP = 1, /* vfp */
_UVRSC_WMMXD = 3, /* Intel WMMX data register */
_UVRSC_WMMXC = 4 /* Intel WMMX control register */
} _Unwind_VRS_RegClass;
typedef enum {
_UVRSD_UINT32 = 0,
_UVRSD_UINT64 = 3,
} _Unwind_VRS_DataRepresentation;
typedef enum {
_UVRSR_OK = 0,
} _Unwind_VRS_Result;
extern void _Unwind_Complete(_Unwind_Exception* exception_object);
extern _Unwind_VRS_Result
_Unwind_VRS_Get(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
uint32_t regno, _Unwind_VRS_DataRepresentation representation,
void *valuep);
extern _Unwind_VRS_Result
_Unwind_VRS_Set(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
uint32_t regno, _Unwind_VRS_DataRepresentation representation,
void *valuep);
extern _Unwind_VRS_Result
_Unwind_VRS_Pop(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
uint32_t discriminator,
_Unwind_VRS_DataRepresentation representation);
#if !defined(_LIBUNWIND_ARM_EHABI)
extern uintptr_t _Unwind_GetGR(struct _Unwind_Context *context, int index);
extern void _Unwind_SetGR(struct _Unwind_Context *context, int index,
uintptr_t new_value);
extern uintptr_t _Unwind_GetIP(struct _Unwind_Context *context);
extern void _Unwind_SetIP(struct _Unwind_Context *, uintptr_t new_value);
#else // defined(_LIBUNWIND_ARM_EHABI)
#define _LIBUNWIND_EXPORT_UNWIND_LEVEL1 static __inline__
// These are de facto helper functions for ARM, which delegate the function
// calls to _Unwind_VRS_Get/Set(). These are not a part of ARM EHABI
// specification, thus these function MUST be inlined. Please don't replace
// these with the "extern" function declaration; otherwise, the program
// including this <unwind.h> header won't be ABI compatible and will result in
// link error when we are linking the program with libgcc.
uintptr_t _Unwind_GetGR(struct _Unwind_Context *context, int index) {
uintptr_t value = 0;
_Unwind_VRS_Get(context, _UVRSC_CORE, (uint32_t)index, _UVRSD_UINT32, &value);
return value;
void _Unwind_SetGR(struct _Unwind_Context *context, int index,
uintptr_t value) {
_Unwind_VRS_Set(context, _UVRSC_CORE, (uint32_t)index, _UVRSD_UINT32, &value);
uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) {
// remove the thumb-bit before returning
return _Unwind_GetGR(context, 15) & (~(uintptr_t)0x1);
void _Unwind_SetIP(struct _Unwind_Context *context, uintptr_t value) {
uintptr_t thumb_bit = _Unwind_GetGR(context, 15) & ((uintptr_t)0x1);
_Unwind_SetGR(context, 15, value | thumb_bit);
#endif // defined(_LIBUNWIND_ARM_EHABI)
extern uintptr_t _Unwind_GetRegionStart(struct _Unwind_Context *context);
extern uintptr_t
_Unwind_GetLanguageSpecificData(struct _Unwind_Context *context);
extern _Unwind_Reason_Code
_Unwind_SjLj_ForcedUnwind(_Unwind_Exception *exception_object,
_Unwind_Stop_Fn stop, void *stop_parameter);
extern _Unwind_Reason_Code
_Unwind_ForcedUnwind(_Unwind_Exception *exception_object,
_Unwind_Stop_Fn stop, void *stop_parameter);
typedef struct _Unwind_FunctionContext *_Unwind_FunctionContext_t;
extern void _Unwind_SjLj_Register(_Unwind_FunctionContext_t fc);
extern void _Unwind_SjLj_Unregister(_Unwind_FunctionContext_t fc);
// The following are semi-suppoted extensions to the C++ ABI
// called by __cxa_rethrow().
extern _Unwind_Reason_Code
_Unwind_SjLj_Resume_or_Rethrow(_Unwind_Exception *exception_object);
extern _Unwind_Reason_Code
_Unwind_Resume_or_Rethrow(_Unwind_Exception *exception_object);
// _Unwind_Backtrace() is a gcc extension that walks the stack and calls the
// _Unwind_Trace_Fn once per frame until it reaches the bottom of the stack
// or the _Unwind_Trace_Fn function returns something other than _URC_NO_REASON.
typedef _Unwind_Reason_Code (*_Unwind_Trace_Fn)(struct _Unwind_Context *,
void *);
extern _Unwind_Reason_Code _Unwind_Backtrace(_Unwind_Trace_Fn, void *);
// _Unwind_GetCFA is a gcc extension that can be called from within a
// personality handler to get the CFA (stack pointer before call) of
// current frame.
extern uintptr_t _Unwind_GetCFA(struct _Unwind_Context *);
// _Unwind_GetIPInfo is a gcc extension that can be called from within a
// personality handler. Similar to _Unwind_GetIP() but also returns in
// *ipBefore a non-zero value if the instruction pointer is at or before the
// instruction causing the unwind. Normally, in a function call, the IP returned
// is the return address which is after the call instruction and may be past the
// end of the function containing the call instruction.
extern uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context,
int *ipBefore);
// __register_frame() is used with dynamically generated code to register the
// FDE for a generated (JIT) code. The FDE must use pc-rel addressing to point
// to its function and optional LSDA.
// __register_frame() has existed in all versions of Mac OS X, but in 10.4 and
// 10.5 it was buggy and did not actually register the FDE with the unwinder.
// In 10.6 and later it does register properly.
extern void __register_frame(const void *fde);
extern void __deregister_frame(const void *fde);
// _Unwind_Find_FDE() will locate the FDE if the pc is in some function that has
// an associated FDE. Note, Mac OS X 10.6 and later, introduces "compact unwind
// info" which the runtime uses in preference to DWARF unwind info. This
// function will only work if the target function has an FDE but no compact
// unwind info.
struct dwarf_eh_bases {
uintptr_t tbase;
uintptr_t dbase;
uintptr_t func;
extern const void *_Unwind_Find_FDE(const void *pc, struct dwarf_eh_bases *);
// This function attempts to find the start (address of first instruction) of
// a function given an address inside the function. It only works if the
// function has an FDE (DWARF unwind info).
// This function is unimplemented on Mac OS X 10.6 and later. Instead, use
// _Unwind_Find_FDE() and look at the dwarf_eh_bases.func result.
extern void *_Unwind_FindEnclosingFunction(void *pc);
// Mac OS X does not support text-rel and data-rel addressing so these functions
// are unimplemented
extern uintptr_t _Unwind_GetDataRelBase(struct _Unwind_Context *context)
extern uintptr_t _Unwind_GetTextRelBase(struct _Unwind_Context *context)
// Mac OS X 10.4 and 10.5 had implementations of these functions in
// libgcc_s.dylib, but they never worked.
/// These functions are no longer available on Mac OS X.
extern void __register_frame_info_bases(const void *fde, void *ob, void *tb,
extern void __register_frame_info(const void *fde, void *ob)
extern void __register_frame_info_table_bases(const void *fde, void *ob,
void *tb, void *db)
extern void __register_frame_info_table(const void *fde, void *ob)
extern void __register_frame_table(const void *fde)
extern void *__deregister_frame_info(const void *fde)
extern void *__deregister_frame_info_bases(const void *fde)
#if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)
#ifndef _WIN32
typedef struct _CONTEXT CONTEXT;
#elif !defined(__MINGW32__) && VER_PRODUCTBUILD < 8000
// This is the common wrapper for GCC-style personality functions with SEH.
void *frame, CONTEXT *ctx,
_Unwind_Personality_Fn pers);
#ifdef __cplusplus
#endif // __UNWIND_H__