--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/luajit/src/lj_err.c	Thu Jan 22 20:10:30 2026 -0800
@@ -0,0 +1,1114 @@
+/*
+** Error handling.
+** Copyright (C) 2005-2023 Mike Pall. See Copyright Notice in luajit.h
+*/
+
+#define lj_err_c
+#define LUA_CORE
+
+#include "lj_obj.h"
+#include "lj_err.h"
+#include "lj_debug.h"
+#include "lj_str.h"
+#include "lj_func.h"
+#include "lj_state.h"
+#include "lj_frame.h"
+#include "lj_ff.h"
+#include "lj_trace.h"
+#include "lj_vm.h"
+#include "lj_strfmt.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. C modules used by Lua code can
+**   throw errors, so these need to have unwind tables, too. Transitively
+**   this applies to all system libraries used by C modules -- at least
+**   when they have callbacks which may throw an error.
+**
+** - INT is faster when actually throwing errors, but this happens rarely.
+**   Setting up error handlers is zero-cost in any case.
+**
+** - INT needs to save *all* callee-saved registers when entering the
+**   interpreter. EXT only needs to save those actually used inside the
+**   interpreter. JIT-compiled code may need to save some more.
+**
+** - 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.
+**
+** - EXT can handle errors from internal helper functions that are called
+**   from JIT-compiled code (except for Windows/x86 and 32 bit ARM).
+**   INT has no choice but to call the panic handler, if this happens.
+**   Note: this is mainly relevant for out-of-memory errors.
+**
+** EXT is the default on all systems where the toolchain produces unwind
+** tables by default (*). This is hard-coded and/or detected in src/Makefile.
+** You can thwart the detection with: TARGET_XCFLAGS=-DLUAJIT_UNWIND_INTERNAL
+**
+** INT is the default on all other systems.
+**
+** EXT can be manually enabled for toolchains that are able to produce
+** conforming unwind tables:
+**   "TARGET_XCFLAGS=-funwind-tables -DLUAJIT_UNWIND_EXTERNAL"
+** As explained above, *all* C code used directly or indirectly by LuaJIT
+** must be compiled with -funwind-tables (or -fexceptions). C++ code must
+** *not* be compiled with -fno-exceptions.
+**
+** If you're unsure whether error handling inside the VM works correctly,
+** try running this and check whether it prints "OK":
+**
+**   luajit -e "print(select(2, load('OK')):match('OK'))"
+**
+** (*) Originally, toolchains only generated unwind tables for C++ code. For
+** interoperability reasons, this can be manually enabled for plain C code,
+** too (with -funwind-tables). With the introduction of the x64 architecture,
+** the corresponding POSIX and Windows ABIs mandated unwind tables for all
+** code. Over the following years most desktop and server platforms have
+** enabled unwind tables by default on all architectures. OTOH mobile and
+** embedded platforms do not consistently mandate unwind tables.
+*/
+
+/* -- Error messages ------------------------------------------------------ */
+
+/* Error message strings. */
+LJ_DATADEF const char *lj_err_allmsg =
+#define ERRDEF(name, msg)	msg "\0"
+#include "lj_errmsg.h"
+;
+
+/* -- 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->base = frame+1;
+	  L->cframe = cframe_prev(cf);
+	  unwindstack(L, top);
+	}
+	return cf;
+      }
+    }
+    if (frame <= tvref(L->stack)+LJ_FR2)
+      break;
+    switch (frame_typep(frame)) {
+    case FRAME_LUA:  /* Lua frame. */
+    case FRAME_LUAP:
+      frame = frame_prevl(frame);
+      break;
+    case FRAME_C:  /* C frame. */
+    unwind_c:
+#if LJ_UNWIND_EXT
+      if (errcode) {
+	L->base = frame_prevd(frame) + 1;
+	L->cframe = cframe_prev(cf);
+	unwindstack(L, frame - LJ_FR2);
+      } 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) {
+	  hook_leave(G(L));  /* Assumes nobody uses coroutines inside hooks. */
+	  L->cframe = NULL;
+	  L->status = (uint8_t)errcode;
+	}
+	return cf;
+      }
+      if (errcode) {
+	L->base = frame_prevd(frame) + 1;
+	L->cframe = cframe_prev(cf);
+	unwindstack(L, frame - LJ_FR2);
+      }
+      return cf;
+    case FRAME_CONT:  /* Continuation frame. */
+      if (frame_iscont_fficb(frame))
+	goto unwind_c;
+      /* fallthrough */
+    case FRAME_VARG:  /* Vararg frame. */
+      frame = frame_prevd(frame);
+      break;
+    case FRAME_PCALL:  /* FF pcall() frame. */
+    case FRAME_PCALLH:  /* FF pcall() frame inside hook. */
+      if (errcode) {
+	if (errcode == LUA_YIELD) {
+	  frame = frame_prevd(frame);
+	  break;
+	}
+	if (frame_typep(frame) == FRAME_PCALL)
+	  hook_leave(G(L));
+	L->base = frame_prevd(frame) + 1;
+	L->cframe = cf;
+	unwindstack(L, L->base);
+      }
+      return (void *)((intptr_t)cf | CFRAME_UNWIND_FF);
+    }
+  }
+  /* No C frame. */
+  if (errcode) {
+    L->base = tvref(L->stack)+1+LJ_FR2;
+    L->cframe = NULL;
+    unwindstack(L, L->base);
+    if (G(L)->panic)
+      G(L)->panic(L);
+    exit(EXIT_FAILURE);
+  }
+  return L;  /* Anything non-NULL will do. */
+}
+
+/* -- External frame unwinding -------------------------------------------- */
+
+#if LJ_ABI_WIN
+
+/*
+** Someone in Redmond owes me several days of my life. A lot of this is
+** undocumented or just plain wrong on MSDN. Some of it can be gathered
+** from 3rd party docs or must be found by trial-and-error. They really
+** don't want you to write your own language-specific exception handler
+** or to interact gracefully with MSVC. :-(
+**
+** Apparently MSVC doesn't call C++ destructors for foreign exceptions
+** unless you compile your C++ code with /EHa. Unfortunately this means
+** catch (...) also catches things like access violations. The use of
+** _set_se_translator doesn't really help, because it requires /EHa, too.
+*/
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#if LJ_TARGET_X86
+typedef void *UndocumentedDispatcherContext;  /* Unused on x86. */
+#else
+/* Taken from: http://www.nynaeve.net/?p=99 */
+typedef struct UndocumentedDispatcherContext {
+  ULONG64 ControlPc;
+  ULONG64 ImageBase;
+  PRUNTIME_FUNCTION FunctionEntry;
+  ULONG64 EstablisherFrame;
+  ULONG64 TargetIp;
+  PCONTEXT ContextRecord;
+  void (*LanguageHandler)(void);
+  PVOID HandlerData;
+  PUNWIND_HISTORY_TABLE HistoryTable;
+  ULONG ScopeIndex;
+  ULONG Fill0;
+} UndocumentedDispatcherContext;
+#endif
+
+/* Another wild guess. */
+extern void __DestructExceptionObject(EXCEPTION_RECORD *rec, int nothrow);
+
+#if LJ_TARGET_X64 && defined(MINGW_SDK_INIT)
+/* Workaround for broken MinGW64 declaration. */
+VOID RtlUnwindEx_FIXED(PVOID,PVOID,PVOID,PVOID,PVOID,PVOID) asm("RtlUnwindEx");
+#define RtlUnwindEx RtlUnwindEx_FIXED
+#endif
+
+#define LJ_MSVC_EXCODE		((DWORD)0xe06d7363)
+#define LJ_GCC_EXCODE		((DWORD)0x20474343)
+
+#define LJ_EXCODE		((DWORD)0xe24c4a00)
+#define LJ_EXCODE_MAKE(c)	(LJ_EXCODE | (DWORD)(c))
+#define LJ_EXCODE_CHECK(cl)	(((cl) ^ LJ_EXCODE) <= 0xff)
+#define LJ_EXCODE_ERRCODE(cl)	((int)((cl) & 0xff))
+
+/* Windows exception handler for interpreter frame. */
+LJ_FUNCA int lj_err_unwind_win(EXCEPTION_RECORD *rec,
+  void *f, CONTEXT *ctx, UndocumentedDispatcherContext *dispatch)
+{
+#if LJ_TARGET_X86
+  void *cf = (char *)f - CFRAME_OFS_SEH;
+#else
+  void *cf = f;
+#endif
+  lua_State *L = cframe_L(cf);
+  int errcode = LJ_EXCODE_CHECK(rec->ExceptionCode) ?
+		LJ_EXCODE_ERRCODE(rec->ExceptionCode) : LUA_ERRRUN;
+  if ((rec->ExceptionFlags & 6)) {  /* EH_UNWINDING|EH_EXIT_UNWIND */
+    /* Unwind internal frames. */
+    err_unwind(L, cf, errcode);
+  } else {
+    void *cf2 = err_unwind(L, cf, 0);
+    if (cf2) {  /* We catch it, so start unwinding the upper frames. */
+      if (rec->ExceptionCode == LJ_MSVC_EXCODE ||
+	  rec->ExceptionCode == LJ_GCC_EXCODE) {
+#if !LJ_TARGET_CYGWIN
+	__DestructExceptionObject(rec, 1);
+#endif
+	setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
+      } else if (!LJ_EXCODE_CHECK(rec->ExceptionCode)) {
+	/* Don't catch access violations etc. */
+	return 1;  /* ExceptionContinueSearch */
+      }
+#if LJ_TARGET_X86
+      UNUSED(ctx);
+      UNUSED(dispatch);
+      /* Call all handlers for all lower C frames (including ourselves) again
+      ** with EH_UNWINDING set. Then call the specified function, passing cf
+      ** and errcode.
+      */
+      lj_vm_rtlunwind(cf, (void *)rec,
+	(cframe_unwind_ff(cf2) && errcode != LUA_YIELD) ?
+	(void *)lj_vm_unwind_ff : (void *)lj_vm_unwind_c, errcode);
+      /* lj_vm_rtlunwind does not return. */
+#else
+      /* Unwind the stack and call all handlers for all lower C frames
+      ** (including ourselves) again with EH_UNWINDING set. Then set
+      ** stack pointer = cf, result = errcode and jump to the specified target.
+      */
+      RtlUnwindEx(cf, (void *)((cframe_unwind_ff(cf2) && errcode != LUA_YIELD) ?
+			       lj_vm_unwind_ff_eh :
+			       lj_vm_unwind_c_eh),
+		  rec, (void *)(uintptr_t)errcode, ctx, dispatch->HistoryTable);
+      /* RtlUnwindEx should never return. */
+#endif
+    }
+  }
+  return 1;  /* ExceptionContinueSearch */
+}
+
+#if LJ_UNWIND_JIT
+
+#if LJ_TARGET_X64
+#define CONTEXT_REG_PC	Rip
+#elif LJ_TARGET_ARM64
+#define CONTEXT_REG_PC	Pc
+#else
+#error "NYI: Windows arch-specific unwinder for JIT-compiled code"
+#endif
+
+/* Windows unwinder for JIT-compiled code. */
+static void err_unwind_win_jit(global_State *g, int errcode)
+{
+  CONTEXT ctx;
+  UNWIND_HISTORY_TABLE hist;
+
+  memset(&hist, 0, sizeof(hist));
+  RtlCaptureContext(&ctx);
+  while (1) {
+    DWORD64 frame, base, addr = ctx.CONTEXT_REG_PC;
+    void *hdata;
+    PRUNTIME_FUNCTION func = RtlLookupFunctionEntry(addr, &base, &hist);
+    if (!func) {  /* Found frame without .pdata: must be JIT-compiled code. */
+      ExitNo exitno;
+      uintptr_t stub = lj_trace_unwind(G2J(g), (uintptr_t)(addr - sizeof(MCode)), &exitno);
+      if (stub) {  /* Jump to side exit to unwind the trace. */
+	ctx.CONTEXT_REG_PC = stub;
+	G2J(g)->exitcode = errcode;
+	RtlRestoreContext(&ctx, NULL);  /* Does not return. */
+      }
+      break;
+    }
+    RtlVirtualUnwind(UNW_FLAG_NHANDLER, base, addr, func,
+		     &ctx, &hdata, &frame, NULL);
+    if (!addr) break;
+  }
+  /* Unwinding failed, if we end up here. */
+}
+#endif
+
+/* Raise Windows exception. */
+static void err_raise_ext(global_State *g, int errcode)
+{
+#if LJ_UNWIND_JIT
+  if (tvref(g->jit_base)) {
+    err_unwind_win_jit(g, errcode);
+    return;  /* Unwinding failed. */
+  }
+#elif LJ_HASJIT
+  /* Cannot catch on-trace errors for Windows/x86 SEH. Unwind to interpreter. */
+  setmref(g->jit_base, NULL);
+#endif
+  UNUSED(g);
+  RaiseException(LJ_EXCODE_MAKE(errcode), 1 /* EH_NONCONTINUABLE */, 0, NULL);
+}
+
+#elif !LJ_NO_UNWIND && (defined(__GNUC__) || defined(__clang__))
+
+/*
+** We have to use our own definitions instead of the mandatory (!) unwind.h,
+** since various OS, distros and compilers mess up the header installation.
+*/
+
+typedef struct _Unwind_Context _Unwind_Context;
+
+#define _URC_OK			0
+#define _URC_FATAL_PHASE2_ERROR	2
+#define _URC_FATAL_PHASE1_ERROR	3
+#define _URC_HANDLER_FOUND	6
+#define _URC_INSTALL_CONTEXT	7
+#define _URC_CONTINUE_UNWIND	8
+#define _URC_FAILURE		9
+
+#define LJ_UEXCLASS		0x4c55414a49543200ULL	/* LUAJIT2\0 */
+#define LJ_UEXCLASS_MAKE(c)	(LJ_UEXCLASS | (uint64_t)(c))
+#define LJ_UEXCLASS_CHECK(cl)	(((cl) ^ LJ_UEXCLASS) <= 0xff)
+#define LJ_UEXCLASS_ERRCODE(cl)	((int)((cl) & 0xff))
+
+#if !LJ_TARGET_ARM
+
+typedef struct _Unwind_Exception
+{
+  uint64_t exclass;
+  void (*excleanup)(int, struct _Unwind_Exception *);
+  uintptr_t p1, p2;
+} __attribute__((__aligned__)) _Unwind_Exception;
+#define UNWIND_EXCEPTION_TYPE	_Unwind_Exception
+
+extern uintptr_t _Unwind_GetCFA(_Unwind_Context *);
+extern void _Unwind_SetGR(_Unwind_Context *, int, uintptr_t);
+extern uintptr_t _Unwind_GetIP(_Unwind_Context *);
+extern void _Unwind_SetIP(_Unwind_Context *, uintptr_t);
+extern void _Unwind_DeleteException(_Unwind_Exception *);
+extern int _Unwind_RaiseException(_Unwind_Exception *);
+
+#define _UA_SEARCH_PHASE	1
+#define _UA_CLEANUP_PHASE	2
+#define _UA_HANDLER_FRAME	4
+#define _UA_FORCE_UNWIND	8
+
+/* DWARF2 personality handler referenced from interpreter .eh_frame. */
+LJ_FUNCA int lj_err_unwind_dwarf(int version, int actions,
+  uint64_t uexclass, _Unwind_Exception *uex, _Unwind_Context *ctx)
+{
+  void *cf;
+  lua_State *L;
+  if (version != 1)
+    return _URC_FATAL_PHASE1_ERROR;
+  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
+    cf = err_unwind(L, cf, errcode);
+    if ((actions & _UA_FORCE_UNWIND)) {
+      return _URC_CONTINUE_UNWIND;
+    } else if (cf) {
+      ASMFunction ip;
+      _Unwind_SetGR(ctx, LJ_TARGET_EHRETREG, errcode);
+      ip = cframe_unwind_ff(cf) ? lj_vm_unwind_ff_eh : lj_vm_unwind_c_eh;
+      _Unwind_SetIP(ctx, (uintptr_t)lj_ptr_strip(ip));
+      return _URC_INSTALL_CONTEXT;
+    }
+#if LJ_TARGET_X86ORX64
+    else if ((actions & _UA_HANDLER_FRAME)) {
+      /* Workaround for ancient libgcc bug. Still present in RHEL 5.5. :-/
+      ** Real fix: http://gcc.gnu.org/viewcvs/trunk/gcc/unwind-dw2.c?r1=121165&r2=124837&pathrev=153877&diff_format=h
+      */
+      _Unwind_SetGR(ctx, LJ_TARGET_EHRETREG, errcode);
+      _Unwind_SetIP(ctx, (uintptr_t)lj_vm_unwind_rethrow);
+      return _URC_INSTALL_CONTEXT;
+    }
+#endif
+#else
+    /* This is not the proper way to escape from the unwinder. We get away with
+    ** it on non-x64 because the interpreter restores all callee-saved regs.
+    */
+    lj_err_throw(L, errcode);
+#if LJ_TARGET_X64
+#error "Broken build system -- only use the provided Makefiles!"
+#endif
+#endif
+  }
+  return _URC_CONTINUE_UNWIND;
+}
+
+#if LJ_UNWIND_EXT && defined(LUA_USE_ASSERT)
+struct dwarf_eh_bases { void *tbase, *dbase, *func; };
+extern const void *_Unwind_Find_FDE(void *pc, struct dwarf_eh_bases *bases);
+
+/* Verify that external error handling actually has a chance to work. */
+void lj_err_verify(void)
+{
+#if !LJ_TARGET_OSX
+  /* Check disabled on MacOS due to brilliant software engineering at Apple. */
+  struct dwarf_eh_bases ehb;
+  lj_assertX(_Unwind_Find_FDE((void *)lj_err_throw, &ehb), "broken build: external frame unwinding enabled, but missing -funwind-tables");
+#endif
+  /* Check disabled, because of broken Fedora/ARM64. See #722.
+  lj_assertX(_Unwind_Find_FDE((void *)_Unwind_RaiseException, &ehb), "broken build: external frame unwinding enabled, but system libraries have no unwind tables");
+  */
+}
+#endif
+
+#if LJ_UNWIND_JIT
+/* DWARF2 personality handler for JIT-compiled code. */
+static int err_unwind_jit(int version, int actions,
+  uint64_t uexclass, _Unwind_Exception *uex, _Unwind_Context *ctx)
+{
+  /* NYI: FFI C++ exception interoperability. */
+  if (version != 1 || !LJ_UEXCLASS_CHECK(uexclass))
+    return _URC_FATAL_PHASE1_ERROR;
+  if ((actions & _UA_SEARCH_PHASE)) {
+    return _URC_HANDLER_FOUND;
+  }
+  if ((actions & _UA_CLEANUP_PHASE)) {
+    global_State *g = *(global_State **)(uex+1);
+    ExitNo exitno;
+    uintptr_t addr = _Unwind_GetIP(ctx);  /* Return address _after_ call. */
+    uintptr_t stub = lj_trace_unwind(G2J(g), addr - sizeof(MCode), &exitno);
+    lj_assertG(tvref(g->jit_base), "unexpected throw across mcode frame");
+    if (stub) {  /* Jump to side exit to unwind the trace. */
+      G2J(g)->exitcode = LJ_UEXCLASS_ERRCODE(uexclass);
+#ifdef LJ_TARGET_MIPS
+      _Unwind_SetGR(ctx, 4, stub);
+      _Unwind_SetGR(ctx, 5, exitno);
+      _Unwind_SetIP(ctx, (uintptr_t)(void *)lj_vm_unwind_stub);
+#else
+      _Unwind_SetIP(ctx, stub);
+#endif
+      return _URC_INSTALL_CONTEXT;
+    }
+    return _URC_FATAL_PHASE2_ERROR;
+  }
+  return _URC_FATAL_PHASE1_ERROR;
+}
+
+/* DWARF2 template frame info for JIT-compiled code.
+**
+** After copying the template to the start of the mcode segment,
+** the frame handler function and the code size is patched.
+** The frame handler always installs a new context to jump to the exit,
+** so don't bother to add any unwind opcodes.
+*/
+static const uint8_t err_frame_jit_template[] = {
+#if LJ_BE
+  0,0,0,
+#endif
+  LJ_64 ? 0x1c : 0x14,  /* CIE length. */
+#if LJ_LE
+  0,0,0,
+#endif
+  0,0,0,0, 1, 'z','P','R',0,  /* CIE mark, CIE version, augmentation. */
+  1, LJ_64 ? 0x78 : 0x7c, LJ_TARGET_EHRAREG,  /* Code/data align, RA. */
+#if LJ_64
+  10, 0, 0,0,0,0,0,0,0,0, 0x1b,  /* Aug. data ABS handler, PCREL|SDATA4 code. */
+  0,0,0,0,0,  /* Alignment. */
+#else
+  6, 0, 0,0,0,0, 0x1b,  /* Aug. data ABS handler, PCREL|SDATA4 code. */
+  0,  /* Alignment. */
+#endif
+#if LJ_BE
+  0,0,0,
+#endif
+  LJ_64 ? 0x14 : 0x10,  /* FDE length. */
+  0,0,0,
+  LJ_64 ? 0x24 : 0x1c,  /* CIE offset. */
+  0,0,0,
+  LJ_64 ? 0x14 : 0x10,  /* Code offset. After Final FDE. */
+#if LJ_LE
+  0,0,0,
+#endif
+  0,0,0,0, 0, 0,0,0, /* Code size, augmentation length, alignment. */
+#if LJ_64
+  0,0,0,0,  /* Alignment. */
+#endif
+  0,0,0,0  /* Final FDE. */
+};
+
+#define ERR_FRAME_JIT_OFS_HANDLER	0x12
+#define ERR_FRAME_JIT_OFS_FDE		(LJ_64 ? 0x20 : 0x18)
+#define ERR_FRAME_JIT_OFS_CODE_SIZE	(LJ_64 ? 0x2c : 0x24)
+#if LJ_TARGET_OSX
+#define ERR_FRAME_JIT_OFS_REGISTER	ERR_FRAME_JIT_OFS_FDE
+#else
+#define ERR_FRAME_JIT_OFS_REGISTER	0
+#endif
+
+extern void __register_frame(const void *);
+extern void __deregister_frame(const void *);
+
+uint8_t *lj_err_register_mcode(void *base, size_t sz, uint8_t *info)
+{
+  ASMFunction handler = (ASMFunction)err_unwind_jit;
+  memcpy(info, err_frame_jit_template, sizeof(err_frame_jit_template));
+#if LJ_ABI_PAUTH
+#if LJ_TARGET_ARM64
+  handler = ptrauth_auth_and_resign(handler,
+    ptrauth_key_function_pointer, 0,
+    ptrauth_key_process_independent_code, info + ERR_FRAME_JIT_OFS_HANDLER);
+#else
+#error "missing pointer authentication support for this architecture"
+#endif
+#endif
+  memcpy(info + ERR_FRAME_JIT_OFS_HANDLER, &handler, sizeof(handler));
+  *(uint32_t *)(info + ERR_FRAME_JIT_OFS_CODE_SIZE) =
+    (uint32_t)(sz - sizeof(err_frame_jit_template) - (info - (uint8_t *)base));
+  __register_frame(info + ERR_FRAME_JIT_OFS_REGISTER);
+#ifdef LUA_USE_ASSERT
+  {
+    struct dwarf_eh_bases ehb;
+    lj_assertX(_Unwind_Find_FDE(info + sizeof(err_frame_jit_template)+1, &ehb),
+	       "bad JIT unwind table registration");
+  }
+#endif
+  return info + sizeof(err_frame_jit_template);
+}
+
+void lj_err_deregister_mcode(void *base, size_t sz, uint8_t *info)
+{
+  UNUSED(base); UNUSED(sz);
+  __deregister_frame(info + ERR_FRAME_JIT_OFS_REGISTER);
+}
+#endif
+
+#else /* LJ_TARGET_ARM */
+
+#define _US_VIRTUAL_UNWIND_FRAME	0
+#define _US_UNWIND_FRAME_STARTING	1
+#define _US_ACTION_MASK			3
+#define _US_FORCE_UNWIND		8
+
+typedef struct _Unwind_Control_Block _Unwind_Control_Block;
+#define UNWIND_EXCEPTION_TYPE	_Unwind_Control_Block
+
+struct _Unwind_Control_Block {
+  uint64_t exclass;
+  uint32_t misc[20];
+};
+
+extern int _Unwind_RaiseException(_Unwind_Control_Block *);
+extern int __gnu_unwind_frame(_Unwind_Control_Block *, _Unwind_Context *);
+extern int _Unwind_VRS_Set(_Unwind_Context *, int, uint32_t, int, void *);
+extern int _Unwind_VRS_Get(_Unwind_Context *, int, uint32_t, int, void *);
+
+static inline uint32_t _Unwind_GetGR(_Unwind_Context *ctx, int r)
+{
+  uint32_t v;
+  _Unwind_VRS_Get(ctx, 0, r, 0, &v);
+  return v;
+}
+
+static inline void _Unwind_SetGR(_Unwind_Context *ctx, int r, uint32_t v)
+{
+  _Unwind_VRS_Set(ctx, 0, r, 0, &v);
+}
+
+extern void lj_vm_unwind_ext(void);
+
+/* ARM unwinder personality handler referenced from interpreter .ARM.extab. */
+LJ_FUNCA int lj_err_unwind_arm(int state, _Unwind_Control_Block *ucb,
+			       _Unwind_Context *ctx)
+{
+  void *cf = (void *)_Unwind_GetGR(ctx, 13);
+  lua_State *L = cframe_L(cf);
+  int errcode;
+
+  switch ((state & _US_ACTION_MASK)) {
+  case _US_VIRTUAL_UNWIND_FRAME:
+    if ((state & _US_FORCE_UNWIND)) break;
+    return _URC_HANDLER_FOUND;
+  case _US_UNWIND_FRAME_STARTING:
+    if (LJ_UEXCLASS_CHECK(ucb->exclass)) {
+      errcode = LJ_UEXCLASS_ERRCODE(ucb->exclass);
+    } else {
+      errcode = LUA_ERRRUN;
+      setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
+    }
+    cf = err_unwind(L, cf, errcode);
+    if ((state & _US_FORCE_UNWIND) || cf == NULL) break;
+    _Unwind_SetGR(ctx, 15, (uint32_t)lj_vm_unwind_ext);
+    _Unwind_SetGR(ctx, 0, (uint32_t)ucb);
+    _Unwind_SetGR(ctx, 1, (uint32_t)errcode);
+    _Unwind_SetGR(ctx, 2, cframe_unwind_ff(cf) ?
+			    (uint32_t)lj_vm_unwind_ff_eh :
+			    (uint32_t)lj_vm_unwind_c_eh);
+    return _URC_INSTALL_CONTEXT;
+  default:
+    return _URC_FAILURE;
+  }
+  if (__gnu_unwind_frame(ucb, ctx) != _URC_OK)
+    return _URC_FAILURE;
+#ifdef LUA_USE_ASSERT
+  /* We should never get here unless this is a forced unwind aka backtrace. */
+  if (_Unwind_GetGR(ctx, 0) == 0xff33aa77) {
+    _Unwind_SetGR(ctx, 0, 0xff33aa88);
+  }
+#endif
+  return _URC_CONTINUE_UNWIND;
+}
+
+#if LJ_UNWIND_EXT && defined(LUA_USE_ASSERT)
+typedef int (*_Unwind_Trace_Fn)(_Unwind_Context *, void *);
+extern int _Unwind_Backtrace(_Unwind_Trace_Fn, void *);
+
+static int err_verify_bt(_Unwind_Context *ctx, int *got)
+{
+  if (_Unwind_GetGR(ctx, 0) == 0xff33aa88) { *got = 2; }
+  else if (*got == 0) { *got = 1; _Unwind_SetGR(ctx, 0, 0xff33aa77); }
+  return _URC_OK;
+}
+
+/* Verify that external error handling actually has a chance to work. */
+void lj_err_verify(void)
+{
+  int got = 0;
+  _Unwind_Backtrace((_Unwind_Trace_Fn)err_verify_bt, &got);
+  lj_assertX(got == 2, "broken build: external frame unwinding enabled, but missing -funwind-tables");
+}
+#endif
+
+/*
+** Note: LJ_UNWIND_JIT is not implemented for 32 bit ARM.
+**
+** The quirky ARM unwind API doesn't have __register_frame().
+** A potential workaround might involve _Unwind_Backtrace.
+** But most 32 bit ARM targets don't qualify for LJ_UNWIND_EXT, anyway,
+** since they are built without unwind tables by default.
+*/
+
+#endif /* LJ_TARGET_ARM */
+
+
+#if LJ_UNWIND_EXT
+static __thread struct {
+  UNWIND_EXCEPTION_TYPE ex;
+  global_State *g;
+} static_uex;
+
+/* Raise external exception. */
+static void err_raise_ext(global_State *g, int errcode)
+{
+  memset(&static_uex, 0, sizeof(static_uex));
+  static_uex.ex.exclass = LJ_UEXCLASS_MAKE(errcode);
+  static_uex.g = g;
+  _Unwind_RaiseException(&static_uex.ex);
+}
+
+#endif
+
+#endif
+
+/* -- Error handling ------------------------------------------------------ */
+
+/* Throw error. Find catch frame, unwind stack and continue. */
+LJ_NOINLINE void LJ_FASTCALL lj_err_throw(lua_State *L, int errcode)
+{
+  global_State *g = G(L);
+  lj_trace_abort(g);
+  L->status = LUA_OK;
+#if LJ_UNWIND_EXT
+  err_raise_ext(g, 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 may happen 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
+#if LJ_HASJIT
+  setmref(g->jit_base, NULL);
+#endif
+  {
+    void *cf = err_unwind(L, NULL, errcode);
+    if (cframe_unwind_ff(cf))
+      lj_vm_unwind_ff(cframe_raw(cf));
+    else
+      lj_vm_unwind_c(cframe_raw(cf), errcode);
+  }
+#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));
+}
+
+/* Out-of-memory error. */
+LJ_NOINLINE void lj_err_mem(lua_State *L)
+{
+  if (L->status == LUA_ERRERR+1)  /* Don't touch the stack during lua_open. */
+    lj_vm_unwind_c(L->cframe, LUA_ERRMEM);
+  if (LJ_HASJIT) {
+    TValue *base = tvref(G(L)->jit_base);
+    if (base) L->base = base;
+  }
+  if (curr_funcisL(L)) L->top = curr_topL(L);
+  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. */
+static ptrdiff_t finderrfunc(lua_State *L)
+{
+  cTValue *frame = L->base-1, *bot = tvref(L->stack)+LJ_FR2;
+  void *cf = L->cframe;
+  while (frame > bot && cf) {
+    while (cframe_nres(cframe_raw(cf)) < 0) {  /* cframe without frame? */
+      if (frame >= restorestack(L, -cframe_nres(cf)))
+	break;
+      if (cframe_errfunc(cf) >= 0)  /* Error handler not inherited (-1)? */
+	return cframe_errfunc(cf);
+      cf = cframe_prev(cf);  /* Else unwind cframe and continue searching. */
+      if (cf == NULL)
+	return 0;
+    }
+    switch (frame_typep(frame)) {
+    case FRAME_LUA:
+    case FRAME_LUAP:
+      frame = frame_prevl(frame);
+      break;
+    case FRAME_C:
+      cf = cframe_prev(cf);
+      /* fallthrough */
+    case FRAME_VARG:
+      frame = frame_prevd(frame);
+      break;
+    case FRAME_CONT:
+      if (frame_iscont_fficb(frame))
+	cf = cframe_prev(cf);
+      frame = frame_prevd(frame);
+      break;
+    case FRAME_CP:
+      if (cframe_canyield(cf)) return 0;
+      if (cframe_errfunc(cf) >= 0)
+	return cframe_errfunc(cf);
+      cf = cframe_prev(cf);
+      frame = frame_prevd(frame);
+      break;
+    case FRAME_PCALL:
+    case FRAME_PCALLH:
+      if (frame_func(frame_prevd(frame))->c.ffid == FF_xpcall)
+	return savestack(L, frame_prevd(frame)+1);  /* xpcall's errorfunc. */
+      return 0;
+    default:
+      lj_assertL(0, "bad frame type");
+      return 0;
+    }
+  }
+  return 0;
+}
+
+/* Runtime error. */
+LJ_NOINLINE void LJ_FASTCALL lj_err_run(lua_State *L)
+{
+  ptrdiff_t ef = (LJ_HASJIT && tvref(G(L)->jit_base)) ? 0 : finderrfunc(L);
+  if (ef) {
+    TValue *errfunc = restorestack(L, ef);
+    TValue *top = L->top;
+    lj_trace_abort(G(L));
+    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+LJ_FR2, top-1);
+    copyTV(L, top-1, errfunc);
+    if (LJ_FR2) setnilV(top++);
+    L->top = top+1;
+    lj_vm_call(L, top, 1+1);  /* Stack: |errfunc|msg| -> |msg| */
+  }
+  lj_err_throw(L, LUA_ERRRUN);
+}
+
+#if LJ_HASJIT
+LJ_NOINLINE void LJ_FASTCALL lj_err_trace(lua_State *L, int errcode)
+{
+  if (errcode == LUA_ERRRUN)
+    lj_err_run(L);
+  else
+    lj_err_throw(L, errcode);
+}
+#endif
+
+/* Formatted runtime error message. */
+LJ_NORET LJ_NOINLINE static void err_msgv(lua_State *L, ErrMsg em, ...)
+{
+  const char *msg;
+  va_list argp;
+  va_start(argp, em);
+  if (LJ_HASJIT) {
+    TValue *base = tvref(G(L)->jit_base);
+    if (base) L->base = base;
+  }
+  if (curr_funcisL(L)) L->top = curr_topL(L);
+  msg = lj_strfmt_pushvf(L, err2msg(em), argp);
+  va_end(argp);
+  lj_debug_addloc(L, msg, L->base-1, NULL);
+  lj_err_run(L);
+}
+
+/* Non-vararg variant for better calling conventions. */
+LJ_NOINLINE void lj_err_msg(lua_State *L, ErrMsg em)
+{
+  err_msgv(L, em);
+}
+
+/* Lexer error. */
+LJ_NOINLINE void lj_err_lex(lua_State *L, GCstr *src, const char *tok,
+			    BCLine line, ErrMsg em, va_list argp)
+{
+  char buff[LUA_IDSIZE];
+  const char *msg;
+  lj_debug_shortname(buff, src, line);
+  msg = lj_strfmt_pushvf(L, err2msg(em), argp);
+  msg = lj_strfmt_pushf(L, "%s:%d: %s", buff, line, msg);
+  if (tok)
+    lj_strfmt_pushf(L, err2msg(LJ_ERR_XNEAR), msg, tok);
+  lj_err_throw(L, LUA_ERRSYNTAX);
+}
+
+/* Typecheck error for operands. */
+LJ_NOINLINE void lj_err_optype(lua_State *L, cTValue *o, ErrMsg opm)
+{
+  const char *tname = lj_typename(o);
+  const char *opname = err2msg(opm);
+  if (curr_funcisL(L)) {
+    GCproto *pt = curr_proto(L);
+    const BCIns *pc = cframe_Lpc(L) - 1;
+    const char *oname = NULL;
+    const char *kind = lj_debug_slotname(pt, pc, (BCReg)(o-L->base), &oname);
+    if (kind)
+      err_msgv(L, LJ_ERR_BADOPRT, opname, kind, oname, tname);
+  }
+  err_msgv(L, LJ_ERR_BADOPRV, opname, tname);
+}
+
+/* Typecheck error for ordered comparisons. */
+LJ_NOINLINE void lj_err_comp(lua_State *L, cTValue *o1, cTValue *o2)
+{
+  const char *t1 = lj_typename(o1);
+  const char *t2 = lj_typename(o2);
+  err_msgv(L, t1 == t2 ? LJ_ERR_BADCMPV : LJ_ERR_BADCMPT, t1, t2);
+  /* This assumes the two "boolean" entries are commoned by the C compiler. */
+}
+
+/* Typecheck error for __call. */
+LJ_NOINLINE void lj_err_optype_call(lua_State *L, TValue *o)
+{
+  /* Gross hack if lua_[p]call or pcall/xpcall fail for a non-callable object:
+  ** L->base still points to the caller. So add a dummy frame with L instead
+  ** of a function. See lua_getstack().
+  */
+  const BCIns *pc = cframe_Lpc(L);
+  if (((ptrdiff_t)pc & FRAME_TYPE) != FRAME_LUA) {
+    const char *tname = lj_typename(o);
+    setframe_gc(o, obj2gco(L), LJ_TTHREAD);
+    if (LJ_FR2) o++;
+    setframe_pc(o, pc);
+    L->top = L->base = o+1;
+    err_msgv(L, LJ_ERR_BADCALL, tname);
+  }
+  lj_err_optype(L, o, LJ_ERR_OPCALL);
+}
+
+/* Error in context of caller. */
+LJ_NOINLINE void lj_err_callermsg(lua_State *L, const char *msg)
+{
+  TValue *frame = NULL, *pframe = NULL;
+  if (!(LJ_HASJIT && tvref(G(L)->jit_base))) {
+    frame = L->base-1;
+    if (frame_islua(frame)) {
+      pframe = frame_prevl(frame);
+    } else if (frame_iscont(frame)) {
+      if (frame_iscont_fficb(frame)) {
+	pframe = frame;
+	frame = NULL;
+      } else {
+	pframe = frame_prevd(frame);
+#if LJ_HASFFI
+	/* Remove frame for FFI metamethods. */
+	if (frame_func(frame)->c.ffid >= FF_ffi_meta___index &&
+	    frame_func(frame)->c.ffid <= FF_ffi_meta___tostring) {
+	  L->base = pframe+1;
+	  L->top = frame;
+	  setcframe_pc(cframe_raw(L->cframe), frame_contpc(frame));
+	}
+#endif
+      }
+    }
+  }
+  lj_debug_addloc(L, msg, pframe, frame);
+  lj_err_run(L);
+}
+
+/* Formatted error in context of caller. */
+LJ_NOINLINE void lj_err_callerv(lua_State *L, ErrMsg em, ...)
+{
+  const char *msg;
+  va_list argp;
+  va_start(argp, em);
+  msg = lj_strfmt_pushvf(L, err2msg(em), argp);
+  va_end(argp);
+  lj_err_callermsg(L, msg);
+}
+
+/* Error in context of caller. */
+LJ_NOINLINE void lj_err_caller(lua_State *L, ErrMsg em)
+{
+  lj_err_callermsg(L, err2msg(em));
+}
+
+/* Argument error message. */
+LJ_NORET LJ_NOINLINE static void err_argmsg(lua_State *L, int narg,
+					    const char *msg)
+{
+  const char *fname = "?";
+  const char *ftype = lj_debug_funcname(L, L->base - 1, &fname);
+  if (narg < 0 && narg > LUA_REGISTRYINDEX)
+    narg = (int)(L->top - L->base) + narg + 1;
+  if (ftype && ftype[3] == 'h' && --narg == 0)  /* Check for "method". */
+    msg = lj_strfmt_pushf(L, err2msg(LJ_ERR_BADSELF), fname, msg);
+  else
+    msg = lj_strfmt_pushf(L, err2msg(LJ_ERR_BADARG), narg, fname, msg);
+  lj_err_callermsg(L, msg);
+}
+
+/* Formatted argument error. */
+LJ_NOINLINE void lj_err_argv(lua_State *L, int narg, ErrMsg em, ...)
+{
+  const char *msg;
+  va_list argp;
+  va_start(argp, em);
+  msg = lj_strfmt_pushvf(L, err2msg(em), argp);
+  va_end(argp);
+  err_argmsg(L, narg, msg);
+}
+
+/* Argument error. */
+LJ_NOINLINE void lj_err_arg(lua_State *L, int narg, ErrMsg em)
+{
+  err_argmsg(L, narg, err2msg(em));
+}
+
+/* Typecheck error for arguments. */
+LJ_NOINLINE void lj_err_argtype(lua_State *L, int narg, const char *xname)
+{
+  const char *tname, *msg;
+  if (narg <= LUA_REGISTRYINDEX) {
+    if (narg >= LUA_GLOBALSINDEX) {
+      tname = lj_obj_itypename[~LJ_TTAB];
+    } else {
+      GCfunc *fn = curr_func(L);
+      int idx = LUA_GLOBALSINDEX - narg;
+      if (idx <= fn->c.nupvalues)
+	tname = lj_typename(&fn->c.upvalue[idx-1]);
+      else
+	tname = lj_obj_typename[0];
+    }
+  } else {
+    TValue *o = narg < 0 ? L->top + narg : L->base + narg-1;
+    tname = o < L->top ? lj_typename(o) : lj_obj_typename[0];
+  }
+  msg = lj_strfmt_pushf(L, err2msg(LJ_ERR_BADTYPE), xname, tname);
+  err_argmsg(L, narg, msg);
+}
+
+/* Typecheck error for arguments. */
+LJ_NOINLINE void lj_err_argt(lua_State *L, int narg, int tt)
+{
+  lj_err_argtype(L, narg, lj_obj_typename[tt+1]);
+}
+
+/* -- Public error handling API ------------------------------------------- */
+
+LUA_API lua_CFunction lua_atpanic(lua_State *L, lua_CFunction panicf)
+{
+  lua_CFunction old = G(L)->panic;
+  G(L)->panic = panicf;
+  return old;
+}
+
+/* Forwarders for the public API (C calling convention and no LJ_NORET). */
+LUA_API int lua_error(lua_State *L)
+{
+  lj_err_run(L);
+  return 0;  /* unreachable */
+}
+
+LUALIB_API int luaL_argerror(lua_State *L, int narg, const char *msg)
+{
+  err_argmsg(L, narg, msg);
+  return 0;  /* unreachable */
+}
+
+LUALIB_API int luaL_typerror(lua_State *L, int narg, const char *xname)
+{
+  lj_err_argtype(L, narg, xname);
+  return 0;  /* unreachable */
+}
+
+LUALIB_API void luaL_where(lua_State *L, int level)
+{
+  int size;
+  cTValue *frame = lj_debug_frame(L, level, &size);
+  lj_debug_addloc(L, "", frame, size ? frame+size : NULL);
+}
+
+LUALIB_API int luaL_error(lua_State *L, const char *fmt, ...)
+{
+  const char *msg;
+  va_list argp;
+  va_start(argp, fmt);
+  msg = lj_strfmt_pushvf(L, fmt, argp);
+  va_end(argp);
+  lj_err_callermsg(L, msg);
+  return 0;  /* unreachable */
+}
+