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Major rewrite of error handling to allow external/internal unwinding.

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Make external unwinding the default on x64.
It's mandatory on WIN64 due to the abundance of callee-saved regs.
Allow piecewise internal frame unwinding and optional cleanup.
Store ERRMEM, ERRERR and ERRCPP early and copy down later.
Use FRAME_CP for lj_vm_resume.
Add lj_vm_unwind_*_eh variants as landing pads for external unwinder.
Use fastcall for lj_vm_unwind_*.
Can drop r12/r13 saves in POSIX/x64 interpreter now.
This commit is contained in:
Mike Pall 2010-01-02 17:42:11 +01:00
parent 8fc9430d06
commit 93ee10642e
6 changed files with 1149 additions and 1009 deletions
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30
src/buildvm_x86.dasc
View File

@ -213,18 +213,16 @@
|
|.define CFRAME_SPACE, aword*5 // Delta for rsp (see <--).
|.macro saveregs
| push rbp; push rbx; push r15; push r14; push r13; push r12
| push rbp; push rbx; push r15; push r14
| sub rsp, CFRAME_SPACE
|.endmacro
|.macro restoreregs
| add rsp, CFRAME_SPACE
| pop r12; pop r13; pop r14; pop r15; pop rbx; pop rbp
| pop r14; pop r15; pop rbx; pop rbp
|.endmacro
|
|//----- 16 byte aligned,
|.define SAVE_RET, aword [rsp+aword*11] //<-- rsp entering interpreter.
|.define SAVE_R6, aword [rsp+aword*10]
|.define SAVE_R5, aword [rsp+aword*9]
|.define SAVE_RET, aword [rsp+aword*9] //<-- rsp entering interpreter.
|.define SAVE_R4, aword [rsp+aword*8]
|.define SAVE_R3, aword [rsp+aword*7]
|.define SAVE_R2, aword [rsp+aword*6]
@ -621,10 +619,10 @@ static void build_subroutines(BuildCtx *ctx, int cmov, int sse)
| mov eax, CARG2d // Error return status for vm_pcall.
| mov rsp, CARG1
|.else
| mov ecx, [esp+4]
| mov eax, [esp+8] // Error return status for vm_pcall.
| mov esp, ecx
| mov eax, FCARG2 // Error return status for vm_pcall.
| mov esp, FCARG1
|.endif
|->vm_unwind_c_eh: // Landing pad for external unwinder.
| mov L:RB, SAVE_L
| mov GL:RB, L:RB->glref
| mov dword GL:RB->vmstate, ~LJ_VMST_C
@ -636,10 +634,10 @@ static void build_subroutines(BuildCtx *ctx, int cmov, int sse)
| and CARG1, CFRAME_RAWMASK
| mov rsp, CARG1
|.else
| mov ecx, [esp+4]
| and ecx, CFRAME_RAWMASK
| mov esp, ecx
| and FCARG1, CFRAME_RAWMASK
| mov esp, FCARG1
|.endif
|->vm_unwind_ff_eh: // Landing pad for external unwinder.
| mov L:RB, SAVE_L
| mov RAa, -8 // Results start at BASE+RA = BASE-8.
| mov RD, 1+1 // Really 1+2 results, incr. later.
@ -718,7 +716,7 @@ static void build_subroutines(BuildCtx *ctx, int cmov, int sse)
| mov L:RB, SAVE_L
| mov RA, INARG_BASE // Caveat: overlaps SAVE_CFRAME!
|.endif
| mov PC, FRAME_C
| mov PC, FRAME_CP
| xor RD, RD
| lea KBASEa, [esp+CFRAME_RESUME]
| mov DISPATCH, L:RB->glref // Setup pointer to dispatch table.
@ -4689,7 +4687,7 @@ static void build_ins(BuildCtx *ctx, BCOp op, int defop, int cmov, int sse)
| movsd FOR_IDX, xmm0
| test RB, RB; js >3
} else {
| jl >3
| jl >3
}
| ucomisd xmm1, xmm0
|1:
@ -4876,8 +4874,6 @@ static void emit_asm_debug(BuildCtx *ctx)
"\t.byte 0x83\n\t.uleb128 0x3\n" /* offset rbx */
"\t.byte 0x8f\n\t.uleb128 0x4\n" /* offset r15 */
"\t.byte 0x8e\n\t.uleb128 0x5\n" /* offset r14 */
"\t.byte 0x8d\n\t.uleb128 0x6\n" /* offset r13 */
"\t.byte 0x8c\n\t.uleb128 0x7\n" /* offset r12 */
#else
"\t.byte 0x85\n\t.uleb128 0x2\n" /* offset ebp */
"\t.byte 0x87\n\t.uleb128 0x3\n" /* offset edi */
@ -4919,8 +4915,6 @@ static void emit_asm_debug(BuildCtx *ctx)
"\t.byte 0x83\n\t.uleb128 0x3\n" /* offset rbx */
"\t.byte 0x8f\n\t.uleb128 0x4\n" /* offset r15 */
"\t.byte 0x8e\n\t.uleb128 0x5\n" /* offset r14 */
"\t.byte 0x8d\n\t.uleb128 0x6\n" /* offset r13 */
"\t.byte 0x8c\n\t.uleb128 0x7\n" /* offset r12 */
#else
"\t.byte 0x85\n\t.uleb128 0x2\n" /* offset ebp */
"\t.byte 0x87\n\t.uleb128 0x3\n" /* offset edi */
@ -4971,8 +4965,6 @@ static void emit_asm_debug(BuildCtx *ctx)
"\t.byte 0x83\n\t.uleb128 0x3\n" /* offset rbx */
"\t.byte 0x8f\n\t.uleb128 0x4\n" /* offset r15 */
"\t.byte 0x8e\n\t.uleb128 0x5\n" /* offset r14 */
"\t.byte 0x8d\n\t.uleb128 0x6\n" /* offset r13 */
"\t.byte 0x8c\n\t.uleb128 0x7\n" /* offset r12 */
#else
"\t.byte 0x84\n\t.byte 0x2\n" /* offset ebp (4 for MACH-O)*/
"\t.byte 0x87\n\t.byte 0x3\n" /* offset edi */

1680
src/buildvm_x86.h
View File

File diff suppressed because it is too large Load Diff

439
src/lj_err.c
View File

@ -20,6 +20,63 @@
#include "lj_trace.h"
#include "lj_vm.h"
/*
** LuaJIT can either use internal or external frame unwinding:
**
** - Internal frame unwinding (INT) is free-standing and doesn't require
** any OS or library support.
**
** - External frame unwinding (EXT) uses the system-provided unwind handler.
**
** Pros and Cons:
**
** - EXT requires unwind tables for *all* functions on the C stack between
** the pcall/catch and the error/throw. This is the default on x64,
** but needs to be manually enabled on x86 for non-C++ code.
**
** - INT is faster when actually throwing errors (but this happens rarely).
** Setting up error handlers is zero-cost in any case.
**
** - EXT provides full interoperability with C++ exceptions. You can throw
** Lua errors or C++ exceptions through a mix of Lua frames and C++ frames.
** C++ destructors are called as needed. C++ exceptions caught by pcall
** are converted to the string "C++ exception". Lua errors can be caught
** with catch (...) in C++.
**
** - INT has only limited support for automatically catching C++ exceptions
** on POSIX systems using DWARF2 stack unwinding. Other systems may use
** the wrapper function feature. Lua errors thrown through C++ frames
** cannot be caught by C++ code and C++ destructors are not run.
**
** INT is the default on x86 systems, EXT is the default on x64 systems.
**
** EXT can only be manually enabled on POSIX/x86 systems using DWARF2 stack
** unwinding with -DLUAJIT_UNWIND_EXTERNAL. *All* C code must be compiled
** with -funwind-tables (or -fexceptions). This includes LuaJIT itself (set
** TARGET_CFLAGS), all of your C/Lua binding code, all loadable C modules
** and all C libraries that have callbacks which may be used to call back
** into Lua. C++ code must *not* be compiled with -fno-exceptions.
**
** EXT cannot be enabled on WIN32 since system exceptions use code-driven SEH.
** EXT is mandatory on WIN64 since the calling convention has an abundance
** of callee-saved registers (rbx, rbp, rsi, rdi, r12-r15, xmm6-xmm15).
** EXT is mandatory on POSIX/x64 since the interpreter doesn't save r12/r13.
*/
#if defined(__ELF__) || defined(__MACH__)
#if LJ_TARGET_X86
#ifdef LUAJIT_UNWIND_EXTERNAL
#define LJ_UNWIND_EXT 1
#endif
#elif LJ_TARGET_X64
#define LJ_UNWIND_EXT 1
#endif
#elif defined(LUA_USE_WIN)
#if LJ_TARGET_X64
#define LJ_UNWIND_EXT 1
#endif
#endif
/* -- Error messages ------------------------------------------------------ */
/* Error message strings. */
@ -374,115 +431,247 @@ LUA_API int lua_getstack(lua_State *L, int level, lua_Debug *ar)
}
}
/* -- Internal frame unwinding -------------------------------------------- */
/* Unwind Lua stack and move error message to new top. */
LJ_NOINLINE static void unwindstack(lua_State *L, TValue *top)
{
lj_func_closeuv(L, top);
if (top < L->top-1) {
copyTV(L, top, L->top-1);
L->top = top+1;
}
lj_state_relimitstack(L);
}
/* Unwind until stop frame. Optionally cleanup frames. */
static void *err_unwind(lua_State *L, void *stopcf, int errcode)
{
TValue *frame = L->base-1;
void *cf = L->cframe;
while (cf) {
int32_t nres = cframe_nres(cframe_raw(cf));
if (nres < 0) { /* C frame without Lua frame? */
TValue *top = restorestack(L, -nres);
if (frame < top) { /* Frame reached? */
if (errcode) {
L->cframe = cframe_prev(cf);
L->base = frame+1;
unwindstack(L, top);
}
return cf;
}
}
if (frame <= L->stack)
break;
switch (frame_typep(frame)) {
case FRAME_LUA: /* Lua frame. */
case FRAME_LUAP:
frame = frame_prevl(frame);
break;
case FRAME_C: /* C frame. */
#if LJ_UNWIND_EXT
if (errcode) {
L->cframe = cframe_prev(cf);
L->base = frame_prevd(frame) + 1;
unwindstack(L, frame);
} else if (cf != stopcf) {
cf = cframe_prev(cf);
frame = frame_prevd(frame);
break;
}
return NULL; /* Continue unwinding. */
#else
UNUSED(stopcf);
cf = cframe_prev(cf);
frame = frame_prevd(frame);
break;
#endif
case FRAME_CP: /* Protected C frame. */
if (cframe_canyield(cf)) { /* Resume? */
if (errcode) {
L->cframe = NULL;
L->status = cast_byte(errcode);
}
return cframe_raw(cf);
}
if (errcode) {
L->cframe = cframe_prev(cf);
L->base = frame_prevd(frame) + 1;
unwindstack(L, frame);
}
return cf;
case FRAME_CONT: /* Continuation frame. */
case FRAME_VARG: /* Vararg frame. */
frame = frame_prevd(frame);
break;
case FRAME_PCALL: /* FF pcall() frame. */
if (errcode)
hook_leave(G(L));
/* fallthrough */
case FRAME_PCALLH: /* FF pcall() frame inside hook. */
if (errcode) {
L->cframe = cf;
L->base = frame_prevd(frame) + 1;
unwindstack(L, L->base);
return NULL; /* Call special handler. */
}
return cf;
}
}
/* No C frame. */
if (errcode) {
L->cframe = NULL;
L->base = L->stack+1;
unwindstack(L, L->base);
if (G(L)->panic)
G(L)->panic(L);
exit(EXIT_FAILURE);
}
return L; /* Anything not-NULL will do. */
}
/* -- External frame unwinding -------------------------------------------- */
#if defined(__ELF__) || defined(__MACH__)
#include <unwind.h>
#define LJ_UEXCLASS 0x4c55414a49543200ULL /* LUAJIT2\0 */
#define LJ_UEXCLASS_MAKE(c) (LJ_UEXCLASS | (_Unwind_Exception_Class)(c))
#define LJ_UEXCLASS_CHECK(cl) (((cl) ^ LJ_UEXCLASS) <= 0xff)
#define LJ_UEXCLASS_ERRCODE(cl) (cast_int((cl) & 0xff))
/* DWARF2 personality handler referenced from interpreter .eh_frame. */
LJ_FUNCA int lj_err_unwind_dwarf(int version, _Unwind_Action actions,
_Unwind_Exception_Class uexclass, struct _Unwind_Exception *uex,
struct _Unwind_Context *ctx)
{
void *cf;
lua_State *L;
if (version != 1)
return _URC_FATAL_PHASE1_ERROR;
UNUSED(uexclass);
cf = (void *)_Unwind_GetCFA(ctx);
L = cframe_L(cf);
if ((actions & _UA_SEARCH_PHASE)) {
#if LJ_UNWIND_EXT
if (err_unwind(L, cf, 0) == NULL)
return _URC_CONTINUE_UNWIND;
#endif
if (!LJ_UEXCLASS_CHECK(uexclass)) {
setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
}
return _URC_HANDLER_FOUND;
}
if ((actions & _UA_CLEANUP_PHASE)) {
int errcode;
if (LJ_UEXCLASS_CHECK(uexclass)) {
errcode = LJ_UEXCLASS_ERRCODE(uexclass);
} else {
if ((actions & _UA_HANDLER_FRAME))
_Unwind_DeleteException(uex);
errcode = LUA_ERRRUN;
}
#if LJ_UNWIND_EXT
if (err_unwind(L, cf, errcode)) {
_Unwind_SetGR(ctx, 0, errcode);
_Unwind_SetIP(ctx, (_Unwind_Ptr)lj_vm_unwind_c_eh);
return _URC_INSTALL_CONTEXT;
} else if ((actions & _UA_HANDLER_FRAME)) {
_Unwind_SetIP(ctx, (_Unwind_Ptr)lj_vm_unwind_ff_eh);
return _URC_INSTALL_CONTEXT;
}
#else
/* This is not the proper way to escape from the unwinder. We get away
** with it on x86 because the interpreter restores all callee-saved regs.
*/
lj_err_throw(L, errcode);
#endif
}
return _URC_CONTINUE_UNWIND;
}
#if LJ_UNWIND_EXT
/* NYI: this is not thread-safe. */
static struct _Unwind_Exception static_uex;
/* Raise DWARF2 exception. */
static void err_raise_ext(int errcode)
{
static_uex.exception_class = LJ_UEXCLASS_MAKE(errcode);
static_uex.exception_cleanup = NULL;
_Unwind_RaiseException(&static_uex);
}
#endif
#elif defined(_WIN64)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#define LJ_EXCODE ((DWORD)0x024c4a00)
#define LJ_EXCODE_MAKE(c) (LJ_EXCODE | (DWORD)(c))
#define LJ_EXCODE_CHECK(cl) (((cl) ^ LJ_EXCODE) <= 0xff)
#define LJ_EXCODE_ERRCODE(cl) (cast_int((cl) & 0xff))
/* NYI: Win64 exception handler for interpreter frame. */
/* Raise Windows exception. */
static void err_raise_ext(int errcode)
{
RaiseException(LJ_EXCODE_MAKE(errcode), 0, 0, NULL);
}
#endif
/* -- Error handling ------------------------------------------------------ */
/* Throw error. Find catch frame, unwind stack and continue. */
LJ_NOINLINE void lj_err_throw(lua_State *L, int errcode)
{
global_State *g = G(L);
lj_trace_abort(g);
setgcrefnull(g->jit_L);
L->status = 0;
#if LJ_UNWIND_EXT
err_raise_ext(errcode);
/*
** A return from this function signals a corrupt C stack that cannot be
** unwound. We have no choice but to call the panic function and exit.
**
** Usually this is caused by a C function without unwind information.
** This should never happen on x64, but may happen on x86 if you've
** manually enabled LUAJIT_UNWIND_EXTERNAL and forgot to recompile *every*
** non-C++ file with -funwind-tables.
*/
if (G(L)->panic)
G(L)->panic(L);
#else
{
void *cf = err_unwind(L, NULL, errcode);
if (cf)
lj_vm_unwind_c(cf, errcode);
else
lj_vm_unwind_ff(cframe_raw(L->cframe));
}
#endif
exit(EXIT_FAILURE);
}
/* Return string object for error message. */
LJ_NOINLINE GCstr *lj_err_str(lua_State *L, ErrMsg em)
{
return lj_str_newz(L, err2msg(em));
}
/* Unwind Lua stack and add error message on top. */
LJ_NOINLINE static void unwindstack(lua_State *L, TValue *top, int errcode)
/* Out-of-memory error. */
LJ_NOINLINE void lj_err_mem(lua_State *L)
{
lj_func_closeuv(L, top);
switch (errcode) {
case LUA_ERRMEM:
setstrV(L, top, lj_err_str(L, LJ_ERR_ERRMEM));
break;
case LUA_ERRERR:
setstrV(L, top, lj_err_str(L, LJ_ERR_ERRERR));
break;
case LUA_ERRSYNTAX:
case LUA_ERRRUN:
copyTV(L, top, L->top - 1);
break;
default:
lua_assert(0);
break;
}
L->top = top+1;
lj_state_relimitstack(L);
}
/* Throw error. Find catch frame, unwind stack and continue. */
LJ_NOINLINE void lj_err_throw(lua_State *L, int errcode)
{
TValue *frame = L->base-1;
void *cf = L->cframe;
global_State *g = G(L);
if (L->status == LUA_ERRERR+1) { /* Don't touch the stack during lua_open. */
lj_vm_unwind_c(cf, errcode);
goto uncaught; /* unreachable */
}
lj_trace_abort(g);
setgcrefnull(g->jit_L);
L->status = 0;
while (cf) {
if (cframe_nres(cframe_raw(cf)) < 0) { /* cframe without frame? */
TValue *top = restorestack(L, -cframe_nres(cf));
if (frame < top) {
L->cframe = cframe_prev(cf);
L->base = frame+1;
unwindstack(L, top, errcode);
lj_vm_unwind_c(cf, errcode);
goto uncaught; /* unreachable */
}
}
if (frame <= L->stack)
break;
switch (frame_typep(frame)) {
case FRAME_LUA:
case FRAME_LUAP:
frame = frame_prevl(frame);
break;
case FRAME_C:
if (cframe_canyield(cf)) goto uncaught;
cf = cframe_prev(cf);
/* fallthrough */
case FRAME_CONT:
case FRAME_VARG:
frame = frame_prevd(frame);
break;
case FRAME_CP:
L->cframe = cframe_prev(cf);
L->base = frame_prevd(frame) + 1;
unwindstack(L, frame, errcode);
lj_vm_unwind_c(cf, errcode);
goto uncaught; /* unreachable */
case FRAME_PCALL:
hook_leave(g);
/* fallthrough */
case FRAME_PCALLH:
L->cframe = cf;
L->base = frame_prevd(frame) + 1;
unwindstack(L, L->base, errcode);
lj_vm_unwind_ff(cf);
goto uncaught; /* unreachable */
default:
lua_assert(0);
goto uncaught;
}
}
/* No catch frame found. Must be a resume or an unprotected error. */
uncaught:
L->status = cast_byte(errcode);
L->cframe = NULL;
if (cframe_canyield(cf)) { /* Resume? */
unwindstack(L, L->top, errcode);
lj_vm_unwind_c(cframe_raw(cf), errcode);
}
/* Better rethrow on main thread than panic. */
{
if (L != mainthread(g))
lj_err_throw(mainthread(g), errcode);
if (g->panic) {
L->base = L->stack+1;
unwindstack(L, L->base, errcode);
g->panic(L);
}
}
exit(EXIT_FAILURE);
if (L->status == LUA_ERRERR+1) /* Don't touch the stack during lua_open. */
lj_vm_unwind_c(L->cframe, LUA_ERRMEM);
setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRMEM));
lj_err_throw(L, LUA_ERRMEM);
}
/* Find error function for runtime errors. Requires an extra stack traversal. */
@ -507,7 +696,6 @@ static ptrdiff_t finderrfunc(lua_State *L)
frame = frame_prevl(frame);
break;
case FRAME_C:
if (cframe_canyield(cf)) return 0;
cf = cframe_prev(cf);
/* fallthrough */
case FRAME_CONT:
@ -515,6 +703,7 @@ static ptrdiff_t finderrfunc(lua_State *L)
frame = frame_prevd(frame);
break;
case FRAME_CP:
if (cframe_canyield(cf)) return 0;
if (cframe_errfunc(cf) >= 0)
return cframe_errfunc(cf);
frame = frame_prevd(frame);
@ -540,8 +729,10 @@ LJ_NOINLINE void lj_err_run(lua_State *L)
TValue *errfunc = restorestack(L, ef);
TValue *top = L->top;
lj_trace_abort(G(L));
if (!tvisfunc(errfunc) || L->status == LUA_ERRERR)
if (!tvisfunc(errfunc) || L->status == LUA_ERRERR) {
setstrV(L, top-1, lj_err_str(L, LJ_ERR_ERRERR));
lj_err_throw(L, LUA_ERRERR);
}
L->status = LUA_ERRERR;
copyTV(L, top, top-1);
copyTV(L, top-1, errfunc);
@ -763,47 +954,3 @@ LUALIB_API int luaL_error(lua_State *L, const char *fmt, ...)
return 0; /* unreachable */
}
/* -- C++ exception support ----------------------------------------------- */
#if defined(__ELF__) || defined(__MACH__)
typedef enum
{
_URC_NO_REASON,
_URC_FOREIGN_EXCEPTION_CAUGHT,
_URC_FATAL_PHASE2_ERROR,
_URC_FATAL_PHASE1_ERROR,
_URC_NORMAL_STOP,
_URC_END_OF_STACK,
_URC_HANDLER_FOUND,
_URC_INSTALL_CONTEXT,
_URC_CONTINUE_UNWIND
} _Unwind_Reason_Code;
#define _UA_SEARCH_PHASE 1
#define _UA_CLEANUP_PHASE 2
#define _UA_HANDLER_FRAME 4
#define _UA_FORCE_UNWIND 8
#define _UA_END_OF_STACK 16
extern void *_Unwind_GetCFA(void *ctx);
extern void _Unwind_DeleteException(void *uex);
/* DWARF2 personality handler referenced from .eh_frame. */
LJ_FUNCA int lj_err_unwind_dwarf(int version, int actions, uint64_t uexclass,
void *uex, void *ctx)
{
if (version != 1)
return _URC_FATAL_PHASE1_ERROR;
UNUSED(uexclass);
if ((actions & _UA_SEARCH_PHASE))
return _URC_HANDLER_FOUND;
if ((actions & _UA_HANDLER_FRAME)) {
void *cf = _Unwind_GetCFA(ctx);
lua_State *L = cframe_L(cf);
_Unwind_DeleteException(uex);
lj_err_msg(L, LJ_ERR_ERRCPP);
}
return _URC_CONTINUE_UNWIND;
}
#endif

1
src/lj_err.h
View File

@ -19,6 +19,7 @@ typedef enum {
LJ_FUNC GCstr *lj_err_str(lua_State *L, ErrMsg em);
LJ_FUNC_NORET void lj_err_throw(lua_State *L, int errcode);
LJ_FUNC_NORET void lj_err_mem(lua_State *L);
LJ_FUNC_NORET void lj_err_run(lua_State *L);
LJ_FUNC_NORET void lj_err_msg(lua_State *L, ErrMsg em);
LJ_FUNC_NORET void lj_err_lex(lua_State *L, const char *src, const char *tok,

2
src/lj_frame.h
View File

@ -81,7 +81,7 @@ enum {
#define CFRAME_OFS_ERRF (3*4)
#define CFRAME_OFS_NRES (2*4)
#define CFRAME_OFS_MULTRES (1*4)
#define CFRAME_SIZE (12*8)
#define CFRAME_SIZE (10*8)
#endif
#else
#error "Missing CFRAME_* definitions for this architecture"

6
src/lj_vm.h
View File

@ -15,8 +15,10 @@ typedef TValue *(*lua_CPFunction)(lua_State *L, lua_CFunction func, void *ud);
LJ_ASMF int lj_vm_cpcall(lua_State *L, lua_CFunction func, void *ud,
lua_CPFunction cp);
LJ_ASMF int lj_vm_resume(lua_State *L, TValue *base, int nres1, ptrdiff_t ef);
LJ_ASMF_NORET void lj_vm_unwind_c(void *cframe, int errcode);
LJ_ASMF_NORET void lj_vm_unwind_ff(void *cframe);
LJ_ASMF_NORET void LJ_FASTCALL lj_vm_unwind_c(void *cframe, int errcode);
LJ_ASMF_NORET void LJ_FASTCALL lj_vm_unwind_ff(void *cframe);
LJ_ASMF void lj_vm_unwind_c_eh(void);
LJ_ASMF void lj_vm_unwind_ff_eh(void);
/* Miscellaneous functions. */
#if LJ_TARGET_X86ORX64