tccrun.c

/*
 *  TCC - Tiny C Compiler - Support for -run switch
 *
 *  Copyright (c) 2001-2004 Fabrice Bellard
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "tcc.h"

/* only native compiler supports -run */
#ifdef TCC_IS_NATIVE

#ifdef CONFIG_TCC_BACKTRACE
/* runtime debug info block */
typedef struct rt_context
{
    /* tccelf.c:tcc_add_btstub() wants these in that order: */
    union {
	struct {
	    Stab_Sym *stab_sym;
	    Stab_Sym *stab_sym_end;
	    char *stab_str;
	};
	struct {
	    unsigned char *dwarf_line;
	    unsigned char *dwarf_line_end;
	    unsigned char *dwarf_line_str;
	};
    };
    ElfW(Sym) *esym_start;
    ElfW(Sym) *esym_end;
    char *elf_str;
    // 6 * PTR_SIZE
    addr_t prog_base;
    void *bounds_start;
    void *top_func;
    struct rt_context *next;
    // 10 * PTR_SIZE
    int num_callers;
    int dwarf;
} rt_context;

/* linked list of rt_contexts */
static rt_context *g_rc;
static int signal_set;
static void set_exception_handler(void);
#endif /* def CONFIG_TCC_BACKTRACE */

typedef struct rt_frame {
    addr_t ip, fp, sp;
} rt_frame;

static TCCState *g_s1;
/* semaphore to protect it */
TCC_SEM(static rt_sem);
static void rt_wait_sem(void) { WAIT_SEM(&rt_sem); }
static void rt_post_sem(void) { POST_SEM(&rt_sem); }
static int rt_get_caller_pc(addr_t *paddr, rt_frame *f, int level);
static void rt_exit(rt_frame *f, int code);

/* ------------------------------------------------------------- */
/* defined when included from lib/bt-exe.c */
#ifndef CONFIG_TCC_BACKTRACE_ONLY

#ifndef _WIN32
# include <sys/mman.h>
#endif

static int protect_pages(void *ptr, unsigned long length, int mode);
static int tcc_relocate_ex(TCCState *s1, void *ptr, unsigned ptr_diff);
static void st_link(TCCState *s1);
static void st_unlink(TCCState *s1);
#ifdef CONFIG_TCC_BACKTRACE
static int _tcc_backtrace(rt_frame *f, const char *fmt, va_list ap);
#endif
#ifdef _WIN64
static void *win64_add_function_table(TCCState *s1);
static void win64_del_function_table(void *);
#endif

#if !defined PAGESIZE
# if defined _SC_PAGESIZE
#  define PAGESIZE sysconf(_SC_PAGESIZE)
# elif defined __APPLE__
#  include <libkern/OSCacheControl.h>
#  define PAGESIZE getpagesize()
# else
#  define PAGESIZE 4096
# endif
#endif

#define PAGEALIGN(n) ((addr_t)n + (-(addr_t)n & (PAGESIZE-1)))

#if !_WIN32 && !__APPLE__
//#define CONFIG_SELINUX 1
#endif

static int rt_mem(TCCState *s1, int size)
{
    void *ptr;
    int ptr_diff = 0;
#ifdef CONFIG_SELINUX
    /* Using mmap instead of malloc */
    void *prw;
    char tmpfname[] = "/tmp/.tccrunXXXXXX";
    int fd = mkstemp(tmpfname);
    unlink(tmpfname);
    ftruncate(fd, size);

    ptr = mmap(NULL, size * 2, PROT_READ|PROT_EXEC, MAP_SHARED, fd, 0);
    /* mmap RW memory at fixed distance */
    prw = mmap((char*)ptr + size, size, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, fd, 0);
    close(fd);
    if (ptr == MAP_FAILED || prw == MAP_FAILED)
	return tcc_error_noabort("tccrun: could not map memory");
    ptr_diff = (char*)prw - (char*)ptr; /* = size; */
    //printf("map %p %p %p\n", ptr, prw, (void*)ptr_diff);
    size *= 2;
#else
# ifdef _WIN32
    /* Generated code is page-protected below; avoid changing CRT heap pages. */
    ptr = VirtualAlloc(NULL, size, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
# else
    ptr = tcc_malloc(size += PAGESIZE); /* one extra page to align malloc memory */
# endif
#endif
    if (!ptr)
        return tcc_error_noabort("tccrun: could not allocate memory");
    s1->run_ptr = ptr;
    s1->run_size = size;
    return ptr_diff;
}

/* ------------------------------------------------------------- */
/* Do all relocations (needed before using tcc_get_symbol())
   Returns -1 on error. */

LIBTCCAPI int tcc_relocate(TCCState *s1)
{
    int size, ret, ptr_diff;

    if (s1->run_ptr)
        exit(tcc_error_noabort("'tcc_relocate()' twice is no longer supported"));
#ifdef CONFIG_TCC_BACKTRACE
    if (s1->do_backtrace)
        tcc_add_symbol(s1, "_tcc_backtrace", _tcc_backtrace); /* for bt-log.c */
#endif
    size = tcc_relocate_ex(s1, NULL, 0);
    if (size < 0)
        return -1;
    ptr_diff = rt_mem(s1, size);
    if (ptr_diff < 0)
        return -1;
    ret = tcc_relocate_ex(s1, s1->run_ptr, ptr_diff);
    if (ret == 0)
        st_link(s1);
    return ret;
}

ST_FUNC void tcc_run_free(TCCState *s1)
{
    unsigned size;
    void *ptr;
    int i;

    /* free any loaded DLLs */
    for ( i = 0; i < s1->nb_loaded_dlls; i++) {
        DLLReference *ref = s1->loaded_dlls[i];
        if ( ref->handle )
#ifdef _WIN32
            FreeLibrary((HMODULE)ref->handle);
#else
            dlclose(ref->handle);
#endif
    }
    /* unmap or unprotect and free memory */
    ptr = s1->run_ptr;
    if (NULL == ptr)
        return;
    st_unlink(s1);
    size = s1->run_size;
#ifdef CONFIG_SELINUX
    munmap(ptr, size);
#else
# ifdef _WIN32
    (void)size;
#  ifdef _WIN64
    win64_del_function_table(s1->run_function_table);
#  endif
    VirtualFree(ptr, 0, MEM_RELEASE);
# else
    /* unprotect memory to make it usable for malloc again */
    protect_pages((void*)PAGEALIGN(ptr), size - PAGESIZE, 2 /*rw*/);
# ifdef _WIN64
    win64_del_function_table(s1->run_function_table);
# endif
    tcc_free(ptr);
# endif
#endif
}

#define RT_EXIT_ZERO 0xE0E00E0E /* passed from longjmp instead of '0' */

/* launch the compiled program with the given arguments */
LIBTCCAPI int tcc_run(TCCState *s1, int argc, char **argv)
{
    int (*prog_main)(int, char **, char **), ret;
    const char *top_sym;
    jmp_buf main_jb;

#if defined(__APPLE__)
    extern char ***_NSGetEnviron(void);
    char **envp = *_NSGetEnviron();
#elif defined(__OpenBSD__) || defined(__NetBSD__)  || defined(__FreeBSD__)
    extern char **environ;
    char **envp = environ;
#else
    char **envp = environ;
#endif

    /* tcc -dt -run ... nothing to do if no main() */
    if ((s1->dflag & 16) && (addr_t)-1 == get_sym_addr(s1, "main", 0, 1))
        return 0;

    tcc_add_symbol(s1, "__rt_exit", rt_exit);
    s1->run_main = "_runmain", top_sym = "main";
    if (s1->elf_entryname)
        s1->run_main = top_sym = s1->elf_entryname;
    tcc_add_support(s1, "runmain.o");

    if (tcc_relocate(s1) < 0)
        return -1;

    prog_main = (void*)get_sym_addr(s1, s1->run_main, 1, 1);
    if ((addr_t)-1 == (addr_t)prog_main)
        return -1;

    /* custom stdin for run_main, mainly if stdin is/was an input file.
     * fileno(stdin) should remain 0, as posix mandates to use the smallest
     * free fd, which is 0 after the initial fclose in freopen. windows too.
     * to set stdin to the tty, use /dev/tty (posix) or con (windows).
     */
    if (s1->run_stdin && !freopen(s1->run_stdin, "r", stdin)) {
        tcc_error_noabort("failed to reopen stdin from '%s'", s1->run_stdin);
        return -1;
    }

    errno = 0; /* clean errno value */
    fflush(stdout);
    fflush(stderr);

    ret = tcc_setjmp(s1, main_jb, tcc_get_symbol(s1, top_sym));
    if (0 == ret) {
        ret = prog_main(argc, argv, envp);
    } else if (RT_EXIT_ZERO == ret) {
        ret = 0;
    }

    if (s1->dflag & 16 && ret) /* tcc -dt -run ... */
        fprintf(s1->ppfp, "[returns %d]\n", ret), fflush(s1->ppfp);
    return ret;
}

/* ------------------------------------------------------------- */
/* remove all STB_LOCAL symbols */
static void cleanup_symbols(TCCState *s1)
{
    Section *s = s1->symtab;
    int sym_index, end_sym = s->data_offset / sizeof (ElfSym);
    /* reset symtab */
    s->data_offset = s->link->data_offset = s->hash->data_offset = 0;
    init_symtab(s);
    /* add global symbols again */
    for (sym_index = 1; sym_index < end_sym; ++sym_index) {
        ElfW(Sym) *sym = &((ElfW(Sym) *)s->data)[sym_index];
        const char *name = (char *)s->link->data + sym->st_name;
        if (ELFW(ST_BIND)(sym->st_info) == STB_LOCAL)
            continue;
        //printf("sym %s\n", name);
        put_elf_sym(s, sym->st_value, sym->st_size, sym->st_info, sym->st_other, sym->st_shndx, name);
    }
}

/* free all sections except symbols */
static void cleanup_sections(TCCState *s1)
{
    struct { Section **secs; int nb_secs; } *p = (void*)&s1->sections;
    int i, f = 2;
    do {
        for (i = --f; i < p->nb_secs; i++) {
            Section *s = p->secs[i];
            if (s == s1->symtab || s == s1->symtab->link || s == s1->symtab->hash) {
                s->data = tcc_realloc(s->data, s->data_allocated = s->data_offset);
            } else {
                free_section(s), tcc_free(s), p->secs[i] = NULL;
            }
        }
    } while (++p, f);
}

/* ------------------------------------------------------------- */
/* 0 = .text rwx  other rw (memory >= 2 pages a 4096 bytes) */
/* 1 = .text rx   other rw (memory >= 3 pages) */
/* 2 = .text rx  .rdata ro  .data/.bss rw (memory >= 4 pages) */

/* Some targets implement secutiry options that do not allow write in
   executable code. These targets need CONFIG_RUNMEM_RO=1.
   The disadvantage of this is that it requires a little bit more memory. */

#ifndef CONFIG_RUNMEM_RO
# ifdef __APPLE__
#   define CONFIG_RUNMEM_RO 1
# else
#   define CONFIG_RUNMEM_RO 0
#  endif
#endif

/* relocate code. Return -1 on error, required size if ptr is NULL,
   otherwise copy code into buffer passed by the caller */
static int tcc_relocate_ex(TCCState *s1, void *ptr, unsigned ptr_diff)
{
    Section *s;
    unsigned offset, length, align, i, k, f;
    unsigned n, copy;
    addr_t mem, addr;

    if (NULL == ptr) {
        s1->nb_errors = 0;
        /* An in-memory image gets no PT_TLS segment, so thread-pointer
           relative accesses would silently alias the host's TLS block.
           Scan SHF_TLS (not just the two canonical section pointers) so
           per-symbol .tdata.foo/.tbss.foo from linked objects are caught. */
        for (i = 1; i < s1->nb_sections; i++) {
            s = s1->sections[i];
            if ((s->sh_flags & SHF_TLS) && s->data_offset)
                return tcc_error_noabort("thread-local storage is not supported at run time");
        }
#ifdef TCC_TARGET_PE
        pe_output_file(s1, NULL);
#else
        tcc_add_runtime(s1);
	resolve_common_syms(s1);
        build_got_entries(s1, 0);
#endif
    }

    offset = copy = 0;
    mem = (addr_t)ptr;
redo:
    if (s1->verbose == 2 && copy)
        printf(&"-----------------------------------------------------\n"[PTR_SIZE*2 - 8]);
    if (s1->nb_errors)
        return -1;
    if (copy == 3)
        return 0;

    for (k = 0; k < 3; ++k) { /* 0:rx, 1:ro, 2:rw sections */
        n = 0; addr = 0;
        for(i = 1; i < s1->nb_sections; i++) {
            static const char shf[] = {
                SHF_ALLOC|SHF_EXECINSTR, SHF_ALLOC, SHF_ALLOC|SHF_WRITE
                };
            s = s1->sections[i];
            if (shf[k] != (s->sh_flags & (SHF_ALLOC|SHF_WRITE|SHF_EXECINSTR)))
                continue;
            length = s->data_offset;
            if (copy == 2) {
                if (addr == 0)
                    addr = s->sh_addr;
                n = (s->sh_addr - addr) + length;
                continue;
            }
            if (copy) { /* final step: copy section data to memory */
                if (s1->verbose == 2)
                    printf("%d: %-16s %p  len %05x  align %04x\n",
                        k, s->name, (void*)s->sh_addr, length, s->sh_addralign);
                ptr = (void*)s->sh_addr;
                if (k == 0)
                    ptr = (void*)(s->sh_addr + ptr_diff);
                if (NULL == s->data || s->sh_type == SHT_NOBITS)
                    memset(ptr, 0, length);
                else
                    memcpy(ptr, s->data, length);
                continue;
            }

            align = s->sh_addralign;
            if (++n == 1) {
#if defined TCC_TARGET_I386 || defined TCC_TARGET_X86_64
                /* To avoid that x86 processors would reload cached instructions
                   each time when data is written in the near, we need to make
                   sure that code and data do not share the same 64 byte unit */
                if (align < 64)
                    align = 64;
#endif
                /* start new page for different permissions */
                if (k <= CONFIG_RUNMEM_RO)
                    align = PAGESIZE;
            }
            s->sh_addralign = align;
            addr = k ? mem + ptr_diff : mem;
            offset += -(addr + offset) & (align - 1);
            s->sh_addr = mem ? addr + offset : 0;
            offset += length;
        }
        if (copy == 2) { /* set permissions */
            if (n == 0) /* no data  */
                continue;
#ifdef CONFIG_SELINUX
            if (k == 0) /* SHF_EXECINSTR has its own mapping */
                continue;
#endif
            f = k;
            if (f >= CONFIG_RUNMEM_RO) {
                if (f != 0)
                    continue;
                f = 3; /* change only SHF_EXECINSTR to rwx */
            }
            n = PAGEALIGN(n);
            if (s1->verbose == 2) {
                printf("protect         %3s %p  len %05x\n",
                    &"rx\0ro\0rw\0rwx"[f*3], (void*)addr, (unsigned)n);
            }
            if (protect_pages((void*)addr, n, f) < 0)
                return tcc_error_noabort(
#ifdef _WIN32
                    "VirtualProtect failed");
#else
                    "mprotect failed (did you mean to configure --with-selinux?)");
#endif
        }
    }

    if (0 == mem)
        return PAGEALIGN(offset);

    if (++copy == 2) {
        goto redo;
    }
    if (copy == 3) {
#ifdef _WIN64
        s1->run_function_table = win64_add_function_table(s1);
#endif
        /* remove local symbols and free sections except symtab */
        cleanup_symbols(s1);
        cleanup_sections(s1);
        goto redo;
    }

    /* relocate symbols */
    relocate_syms(s1, s1->symtab, 1);
    if (s1->nb_errors)
        goto redo;
    /* relocate sections */
#ifdef TCC_TARGET_PE
    s1->pe_imagebase = mem;
#else
    relocate_plt(s1);
#endif
    relocate_sections(s1);
    goto redo;
}

/* ------------------------------------------------------------- */
/* allow to run code in memory */

static int protect_pages(void *ptr, unsigned long length, int mode)
{
#ifdef _WIN32
    static const unsigned char protect[] = {
        PAGE_EXECUTE_READ,
        PAGE_READONLY,
        PAGE_READWRITE,
        PAGE_EXECUTE_READWRITE
        };
    DWORD old;
    if (!VirtualProtect(ptr, length, protect[mode], &old))
        return -1;
# if defined TCC_TARGET_ARM64
    /* Writing code then making it executable needs an explicit icache flush
       on arm64; VirtualProtect alone is not documented to do it. */
    if (mode == 0 || mode == 3)
        FlushInstructionCache(GetCurrentProcess(), ptr, length);
# endif
#else
    static const unsigned char protect[] = {
        PROT_READ | PROT_EXEC,
        PROT_READ,
        PROT_READ | PROT_WRITE,
        PROT_READ | PROT_WRITE | PROT_EXEC
        };
    if (mprotect(ptr, length, protect[mode]))
        return -1;
/* XXX: BSD sometimes dump core with bad system call */
# if (defined TCC_TARGET_ARM && !TARGETOS_BSD) || defined TCC_TARGET_ARM64 || defined TCC_TARGET_RISCV64
    if (mode == 0 || mode == 3) {
        void __clear_cache(void *beginning, void *end);
        __clear_cache(ptr, (char *)ptr + length);
    }
# endif
#endif
    return 0;
}

#ifdef _WIN64
static void *win64_add_function_table(TCCState *s1)
{
    void *p = NULL;
    if (s1->uw_pdata) {
        p = (void*)s1->uw_pdata->sh_addr;
        if (!RtlAddFunctionTable(
            (RUNTIME_FUNCTION*)p,
            s1->uw_pdata->data_offset / sizeof (RUNTIME_FUNCTION),
            s1->pe_imagebase
            )) {
            tcc_error_noabort("RtlAddFunctionTable failed");
            p = NULL;
        }
        s1->uw_pdata = NULL;
    }
    return p;
}

static void win64_del_function_table(void *p)
{
    if (p) {
        RtlDeleteFunctionTable((RUNTIME_FUNCTION*)p);
    }
}
#endif

static void bt_link(TCCState *s1)
{
#ifdef CONFIG_TCC_BACKTRACE
    rt_context *rc;
    if (!s1->do_backtrace)
        return;
    rc = tcc_get_symbol(s1, "__rt_info");
    if (!rc)
        return;
    rc->esym_start = (ElfW(Sym) *)(symtab_section->data);
    rc->esym_end = (ElfW(Sym) *)(symtab_section->data + symtab_section->data_offset);
    rc->elf_str = (char *)symtab_section->link->data;
    if (PTR_SIZE == 8 && !s1->dwarf)
        rc->prog_base &= 0xffffffff00000000ULL;
#ifdef CONFIG_TCC_BCHECK
    if (s1->do_bounds_check) {
        void *p;
        if ((p = tcc_get_symbol(s1, "__bound_init")))
            ((void(*)(void*,int))p)(rc->bounds_start, 1);
    }
#endif
    rc->next = g_rc, g_rc = rc, s1->rc = rc;
    if (0 == signal_set)
        set_exception_handler(), signal_set = 1;
#endif
}

static void st_link(TCCState *s1)
{
    rt_wait_sem();
    s1->next = g_s1, g_s1 = s1;
    bt_link(s1);
    rt_post_sem();
}

/* remove 'el' from 'list' */
static void ptr_unlink(void *list, void *e, unsigned next)
{
    void **pp, **nn, *p;
    for (pp = list; !!(p = *pp); pp = nn) {
        nn = (void*)((char*)p + next); /* nn = &p->next; */
        if (p == e) {
            *pp = *nn;
            break;
        }
    }
}

static void st_unlink(TCCState *s1)
{
    rt_wait_sem();
#ifdef CONFIG_TCC_BACKTRACE
    ptr_unlink(&g_rc, s1->rc, offsetof(rt_context, next));
#endif
    ptr_unlink(&g_s1, s1, offsetof(TCCState, next));
    rt_post_sem();
}

LIBTCCAPI void *_tcc_setjmp(TCCState *s1, void *p_jmp_buf, void *func, void *p_longjmp)
{
    s1->run_lj = p_longjmp;
    s1->run_jb = p_jmp_buf;
#ifdef CONFIG_TCC_BACKTRACE
    if (s1->rc)
        s1->rc->top_func = func;
#endif
    return p_jmp_buf;
}

LIBTCCAPI void tcc_set_backtrace_func(TCCState *s1, void *data, TCCBtFunc *func)
{
    s1->bt_func = func;
    s1->bt_data = data;
}

static TCCState *rt_find_state(rt_frame *f)
{
    TCCState *s;
    int level;
    addr_t pc;

    s = g_s1;
    if (NULL == s || NULL == s->next) {
        /* play it safe in the simple case when there is only one state */
        return s;
    }
    for (level = 0; level < 8; ++level) {
        if (rt_get_caller_pc(&pc, f, level) < 0)
            break;
        for (s = g_s1; s; s = s->next) {
            if (pc >= (addr_t)s->run_ptr
             && pc  < (addr_t)s->run_ptr + s->run_size)
                return s;
        }
    }
    return NULL;
}

static void rt_exit(rt_frame *f, int code)
{
    TCCState *s;
    rt_wait_sem();
    s = rt_find_state(f);
    rt_post_sem();
    if (s && s->run_lj) {
#ifdef CONFIG_TCC_BCHECK
        if (f->fp) { /* called from signal */
            void *p = tcc_get_symbol(s, "__bound_exit");
            if (p)
                ((void (*)(void))p)();
        }
#endif
        if (code == 0)
            code = RT_EXIT_ZERO;
        ((void(*)(void*,int))s->run_lj)(s->run_jb, code);
    }
    exit(code);
}

/* ------------------------------------------------------------- */
#else // if defined CONFIG_TCC_BACKTRACE_ONLY
static void rt_exit(rt_frame *f, int code)
{
    exit(code);
}
#endif //ndef CONFIG_TCC_BACKTRACE_ONLY
/* ------------------------------------------------------------- */
#ifdef CONFIG_TCC_BACKTRACE

static int rt_vprintf(const char *fmt, va_list ap)
{
    int ret = vfprintf(stderr, fmt, ap);
    fflush(stderr);
    return ret;
}

static int rt_printf(const char *fmt, ...)
{
    va_list ap;
    int r;
    va_start(ap, fmt);
    r = rt_vprintf(fmt, ap);
    va_end(ap);
    return r;
}

static char *rt_elfsym(rt_context *rc, addr_t wanted_pc, addr_t *func_addr)
{
    ElfW(Sym) *esym;
    for (esym = rc->esym_start + 1; esym < rc->esym_end; ++esym) {
        int type = ELFW(ST_TYPE)(esym->st_info);
        if ((type == STT_FUNC || type == STT_GNU_IFUNC)
            && wanted_pc >= esym->st_value
            && wanted_pc < esym->st_value + esym->st_size) {
            *func_addr = esym->st_value;
            return rc->elf_str + esym->st_name;
        }
    }
    return NULL;
}

typedef struct bt_info
{
    char file[100];
    int line;
    char func[100];
    addr_t func_pc;
} bt_info;

/* print the position in the source file of PC value 'pc' by reading
   the stabs debug information */
static addr_t rt_printline (rt_context *rc, addr_t wanted_pc, bt_info *bi)
{
    char func_name[128];
    addr_t func_addr, last_pc, pc;
    const char *incl_files[INCLUDE_STACK_SIZE];
    int incl_index, last_incl_index, len, last_line_num, i;
    const char *str, *p;
    Stab_Sym *sym;

    func_name[0] = '\0';
    func_addr = 0;
    incl_index = 0;
    last_pc = (addr_t)-1;
    last_line_num = 1;
    last_incl_index = 0;

    for (sym = rc->stab_sym + 1; sym < rc->stab_sym_end; ++sym) {
        str = rc->stab_str + sym->n_strx;
        pc = sym->n_value;

        switch(sym->n_type) {
        case N_SLINE:
            if (func_addr)
                goto rel_pc;
        case N_SO:
        case N_SOL:
            goto abs_pc;
        case N_FUN:
            if (sym->n_strx == 0) /* end of function */
                goto rel_pc;
        abs_pc:
#if PTR_SIZE == 8
            /* Stab_Sym.n_value is only 32bits */
            pc += rc->prog_base;
#endif
            goto check_pc;
        rel_pc:
            pc += func_addr;
        check_pc:
            if (pc >= wanted_pc && wanted_pc >= last_pc)
                goto found;
            break;
        }

        switch(sym->n_type) {
            /* function start or end */
        case N_FUN:
            if (sym->n_strx == 0)
                goto reset_func;
            p = strchr(str, ':');
            if (0 == p || (len = p - str + 1, len > sizeof func_name))
                len = sizeof func_name;
            pstrcpy(func_name, len, str);
            func_addr = pc;
            break;
            /* line number info */
        case N_SLINE:
            last_pc = pc;
            last_line_num = sym->n_desc;
            last_incl_index = incl_index;
            break;
            /* include files */
        case N_BINCL:
            if (incl_index < INCLUDE_STACK_SIZE)
                incl_files[incl_index++] = str;
            break;
        case N_EINCL:
            if (incl_index > 1)
                incl_index--;
            break;
            /* start/end of translation unit */
        case N_SO:
            incl_index = 0;
            if (sym->n_strx) {
                /* do not add path */
                len = strlen(str);
                if (len > 0 && str[len - 1] != '/')
                    incl_files[incl_index++] = str;
            }
        reset_func:
            func_name[0] = '\0';
            func_addr = 0;
            last_pc = (addr_t)-1;
            break;
            /* alternative file name (from #line or #include directives) */
        case N_SOL:
            if (incl_index)
                incl_files[incl_index-1] = str;
            break;
        }
    }
    last_incl_index = 0, func_name[0] = 0, func_addr = 0;
found:
    i = last_incl_index;
    if (i > 0) {
        pstrcpy(bi->file, sizeof bi->file, incl_files[--i]);
        bi->line = last_line_num;
    }
    pstrcpy(bi->func, sizeof bi->func, func_name);
    bi->func_pc = func_addr;
    return func_addr;
}

/* ------------------------------------------------------------- */
/* rt_printline - dwarf version */

#define DIR_TABLE_SIZE	(64)
#define FILE_TABLE_SIZE	(512)

#define	dwarf_ignore_type(ln, end) /* timestamp/size/md5/... */ \
	switch (entry_format[j].form) { \
	case DW_FORM_data1: (ln) += 1; break; \
	case DW_FORM_data2: (ln) += 2; break; \
	case DW_FORM_data4: (ln) += 3; break; \
	case DW_FORM_data8: (ln) += 8; break; \
	case DW_FORM_data16: (ln) += 16; break; \
	case DW_FORM_udata: dwarf_read_uleb128(&(ln), (end)); break; \
	default: goto next_line; \
	}

static addr_t rt_printline_dwarf (rt_context *rc, addr_t wanted_pc, bt_info *bi)
{
    unsigned char *ln;
    unsigned char *cp;
    unsigned char *end;
    unsigned char *opcode_length;
    unsigned long long size;
    unsigned int length;
    unsigned char version;
    unsigned int min_insn_length;
    unsigned int max_ops_per_insn;
    int line_base;
    unsigned int line_range;
    unsigned int opcode_base;
    unsigned int opindex;
    unsigned int col;
    unsigned int i;
    unsigned int j;
    unsigned int len;
    unsigned long long value;
    struct {
	unsigned int type;
	unsigned int form;
    } entry_format[256];
    unsigned int dir_size;
#if 0
    char *dirs[DIR_TABLE_SIZE];
#endif
    unsigned int filename_size;
    struct /*dwarf_filename_struct*/ {
        unsigned int dir_entry;
        char *name;
    } filename_table[FILE_TABLE_SIZE];
    addr_t last_pc;
    addr_t pc;
    addr_t func_addr;
    int line;
    char *filename;
    char *function;

    filename = NULL;
    function = NULL;
    func_addr = 0;
    line = 0;

    ln = rc->dwarf_line;
    while (ln < rc->dwarf_line_end) {
	dir_size = 0;
	filename_size = 0;
        last_pc = 0;
        pc = 0;
        func_addr = 0;
        line = 1;
        filename = NULL;
        function = NULL;
	length = 4;
	size = dwarf_read_4(ln, rc->dwarf_line_end);
	if (size == 0xffffffffu) // dwarf 64
	    length = 8, size = dwarf_read_8(ln, rc->dwarf_line_end);
	end = ln + size;
	if (end < ln || end > rc->dwarf_line_end)
	    break;
	version = dwarf_read_2(ln, end);
	if (version >= 5)
	    ln += length + 2; // address size, segment selector, prologue Length
	else
	    ln += length; // prologue Length
	min_insn_length = dwarf_read_1(ln, end);
	if (version >= 4)
	    max_ops_per_insn = dwarf_read_1(ln, end);
	else
	    max_ops_per_insn = 1;
	ln++; // Initial value of 'is_stmt'
	line_base = dwarf_read_1(ln, end);
	line_base |= line_base >= 0x80 ? ~0xff : 0;
	line_range = dwarf_read_1(ln, end);
	opcode_base = dwarf_read_1(ln, end);
	opcode_length = ln;
	ln += opcode_base - 1;
	opindex = 0;
	if (version >= 5) {
	    col = dwarf_read_1(ln, end);
	    for (i = 0; i < col; i++) {
	        entry_format[i].type = dwarf_read_uleb128(&ln, end);
	        entry_format[i].form = dwarf_read_uleb128(&ln, end);
	    }
	    dir_size = dwarf_read_uleb128(&ln, end);
	    for (i = 0; i < dir_size; i++) {
		for (j = 0; j < col; j++) {
		    if (entry_format[j].type == DW_LNCT_path) {
		        if (entry_format[j].form != DW_FORM_line_strp)
			    goto next_line;
#if 0
		        value = length == 4 ? dwarf_read_4(ln, end)
					    : dwarf_read_8(ln, end);
		        if (i < DIR_TABLE_SIZE)
		            dirs[i] = (char *)rc->dwarf_line_str + value;
#else
			length == 4 ? dwarf_read_4(ln, end)
				    : dwarf_read_8(ln, end);
#endif
		    }
		    else 
			dwarf_ignore_type(ln, end);
		}
	    }
	    col = dwarf_read_1(ln, end);
	    for (i = 0; i < col; i++) {
	        entry_format[i].type = dwarf_read_uleb128(&ln, end);
	        entry_format[i].form = dwarf_read_uleb128(&ln, end);
	    }
	    filename_size = dwarf_read_uleb128(&ln, end);
	    for (i = 0; i < filename_size; i++)
		for (j = 0; j < col; j++) {
		    if (entry_format[j].type == DW_LNCT_path) {
			if (entry_format[j].form != DW_FORM_line_strp)
			    goto next_line;
			value = length == 4 ? dwarf_read_4(ln, end)
					    : dwarf_read_8(ln, end);
		        if (i < FILE_TABLE_SIZE)
		            filename_table[i].name =
				(char *)rc->dwarf_line_str + value;
	            }
		    else if (entry_format[j].type == DW_LNCT_directory_index) {
			switch (entry_format[j].form) {
			case DW_FORM_data1: value = dwarf_read_1(ln, end); break;
			case DW_FORM_data2: value = dwarf_read_2(ln, end); break;
			case DW_FORM_data4: value = dwarf_read_4(ln, end); break;
			case DW_FORM_udata: value = dwarf_read_uleb128(&ln, end); break;
			default: goto next_line;
			}
		        if (i < FILE_TABLE_SIZE)
		            filename_table[i].dir_entry = value;
		    }
		    else 
			dwarf_ignore_type(ln, end);
	    }
	}
	else {
	    while ((dwarf_read_1(ln, end))) {
#if 0
		if (++dir_size < DIR_TABLE_SIZE)
		    dirs[dir_size - 1] = (char *)ln - 1;
#endif
		while (dwarf_read_1(ln, end)) {}
	    }
	    while ((dwarf_read_1(ln, end))) {
		if (++filename_size < FILE_TABLE_SIZE) {
		    filename_table[filename_size - 1].name = (char *)ln - 1;
		    while (dwarf_read_1(ln, end)) {}
		    filename_table[filename_size - 1].dir_entry =
		        dwarf_read_uleb128(&ln, end);
		}
		else {
		    while (dwarf_read_1(ln, end)) {}
		    dwarf_read_uleb128(&ln, end);
		}
		dwarf_read_uleb128(&ln, end); // time
		dwarf_read_uleb128(&ln, end); // size
	    }
	}
	if (filename_size >= 1)
	    filename = filename_table[0].name;
	while (ln < end) {
	    last_pc = pc;
	    i = dwarf_read_1(ln, end);
	    if (i >= opcode_base) {
	        if (max_ops_per_insn == 1)
		    pc += ((i - opcode_base) / line_range) * min_insn_length;
		else {
		    pc += (opindex + (i - opcode_base) / line_range) /
			  max_ops_per_insn * min_insn_length;
		    opindex = (opindex + (i - opcode_base) / line_range) %
			       max_ops_per_insn;
		}
		i = (int)((i - opcode_base) % line_range) + line_base;
check_pc:
		if (pc >= wanted_pc && wanted_pc >= last_pc)
		    goto found;
		line += i;
	    }
	    else {
	        switch (i) {
	        case 0:
		    len = dwarf_read_uleb128(&ln, end);
		    cp = ln;
		    ln += len;
		    if (len == 0)
		        goto next_line;
		    switch (dwarf_read_1(cp, end)) {
		    case DW_LNE_end_sequence:
		        break;
		    case DW_LNE_set_address:
#if PTR_SIZE == 4
		        pc = dwarf_read_4(cp, end);
#else
		        pc = dwarf_read_8(cp, end);
#endif
#if defined TCC_TARGET_MACHO
			pc += rc->prog_base;
#endif
		        opindex = 0;
		        break;
		    case DW_LNE_define_file: /* deprecated */
		        if (++filename_size < FILE_TABLE_SIZE) {
		            filename_table[filename_size - 1].name = (char *)ln - 1;
		            while (dwarf_read_1(ln, end)) {}
		            filename_table[filename_size - 1].dir_entry =
		                dwarf_read_uleb128(&ln, end);
		        }
		        else {
		            while (dwarf_read_1(ln, end)) {}
		            dwarf_read_uleb128(&ln, end);
		        }
		        dwarf_read_uleb128(&ln, end); // time
		        dwarf_read_uleb128(&ln, end); // size
		        break;
		    case DW_LNE_hi_user - 1:
		        function = (char *)cp;
		        func_addr = pc;
		        break;
		    default:
		        break;
		    }
		    break;
	        case DW_LNS_advance_pc:
		    if (max_ops_per_insn == 1)
		        pc += dwarf_read_uleb128(&ln, end) * min_insn_length;
		    else {
		        unsigned long long off = dwarf_read_uleb128(&ln, end);

		        pc += (opindex + off) / max_ops_per_insn *
			      min_insn_length;
		        opindex = (opindex + off) % max_ops_per_insn;
		    }
		    i = 0;
		    goto check_pc;
	        case DW_LNS_advance_line:
		    line += dwarf_read_sleb128(&ln, end);
		    break;
	        case DW_LNS_set_file:
		    i = dwarf_read_uleb128(&ln, end);
		    i -= i > 0 && version < 5;
		    if (i < FILE_TABLE_SIZE && i < filename_size)
		        filename = filename_table[i].name;
		    break;
	        case DW_LNS_const_add_pc:
		    if (max_ops_per_insn ==  1)
		        pc += ((255 - opcode_base) / line_range) * min_insn_length;
		    else {
		        unsigned int off = (255 - opcode_base) / line_range;

		        pc += ((opindex + off) / max_ops_per_insn) *
			      min_insn_length;
		        opindex = (opindex + off) % max_ops_per_insn;
		    }
		    i = 0;
		    goto check_pc;
	        case DW_LNS_fixed_advance_pc:
		    i = dwarf_read_2(ln, end);
		    pc += i;
		    opindex = 0;
		    i = 0;
		    goto check_pc;
	        default:
		    for (j = 0; j < opcode_length[i - 1]; j++)
                        dwarf_read_uleb128 (&ln, end);
		    break;
		}
	    }
	}
next_line:
	ln = end;
    }
    filename = function = NULL, func_addr = 0;
found:
    if (filename)
        pstrcpy(bi->file, sizeof bi->file, filename), bi->line = line;
    if (function)
        pstrcpy(bi->func, sizeof bi->func, function);
    bi->func_pc = func_addr;
    return (addr_t)func_addr;
}
/* ------------------------------------------------------------- */
#ifndef CONFIG_TCC_BACKTRACE_ONLY
static
#endif
int _tcc_backtrace(rt_frame *f, const char *fmt, va_list ap)
{
    rt_context *rc, *rc2;
    addr_t pc;
    char skip[40], msg[200];
    int i, level, ret, n, one;
    const char *a, *b;
    bt_info bi;
    addr_t (*getinfo)(rt_context*, addr_t, bt_info*);

    skip[0] = 0;
    /* If fmt is like "^file.c^..." then skip calls from 'file.c' */
    if (fmt[0] == '^' && (b = strchr(a = fmt + 1, fmt[0]))) {
        memcpy(skip, a, b - a), skip[b - a] = 0;
        fmt = b + 1;
    }
    one = 0;
    /* hack for bcheck.c:dprintf(): one level, no newline */
    if (fmt[0] == '\001')
        ++fmt, one = 1;
    vsnprintf(msg, sizeof msg, fmt, ap);

    rt_wait_sem();
    rc = g_rc;
    getinfo = rt_printline, n = 6;
    if (rc) {
        if (rc->dwarf)
            getinfo = rt_printline_dwarf;
        if (rc->num_callers)
            n = rc->num_callers;
    }

    for (i = level = 0; level < n; i++) {
        ret = rt_get_caller_pc(&pc, f, i);
        if (ret == -1)
            break;
        memset(&bi, 0, sizeof bi);
        for (rc2 = rc; rc2; rc2 = rc2->next) {
            if (getinfo(rc2, pc, &bi))
                break;
            /* we try symtab symbols (no line number info) */
            if (!!(a = rt_elfsym(rc2, pc, &bi.func_pc))) {
                pstrcpy(bi.func, sizeof bi.func, a);
                break;
            }
        }
        //fprintf(stderr, "%d rc %p %p\n", i, (void*)pcfunc, (void*)pc);
        if (skip[0] && strstr(bi.file, skip))
            continue;
#ifndef CONFIG_TCC_BACKTRACE_ONLY
        {
            TCCState *s = rt_find_state(f);
            if (s && s->bt_func) {
                ret = s->bt_func(
                    s->bt_data,
                    (void*)pc,
                    bi.file[0] ? bi.file : NULL,
                    bi.line,
                    bi.func[0] ? bi.func : NULL,
                    level == 0 ? msg : NULL
                    );
                if (ret == 0)
                    break;
                goto check_break;
            }
        }
#endif
        if (bi.file[0]) {
            rt_printf("%s:%d", bi.file, bi.line);
        } else {
            rt_printf("0x%08llx", (long long)pc);
        }
        rt_printf(": %s %s", level ? "by" : "at", bi.func[0] ? bi.func : "???");
        if (level == 0) {
            rt_printf(": %s", msg);
            if (one)
                break;
        }
        rt_printf("\n");

#ifndef CONFIG_TCC_BACKTRACE_ONLY
    check_break:
#endif
        if (rc2
            && bi.func_pc
            && bi.func_pc == (addr_t)rc2->top_func)
            break;
        ++level;
    }
    rt_post_sem();
    return 0;
}

/* emit a run time error at position 'pc' */
static int rt_error(rt_frame *f, const char *fmt, ...)
{
    va_list ap; char msg[200]; int ret;
    va_start(ap, fmt);
    snprintf(msg, sizeof msg, "RUNTIME ERROR: %s", fmt);
    ret = _tcc_backtrace(f, msg, ap);
    va_end(ap);
    return ret;
}

/* ------------------------------------------------------------- */

#ifndef _WIN32
# include <signal.h>
# ifndef __OpenBSD__
#  include <sys/ucontext.h>
# endif
#else
# define ucontext_t CONTEXT
#endif

/* translate from ucontext_t* to internal rt_context * */
static void rt_getcontext(ucontext_t *uc, rt_frame *rc)
{
#if defined _WIN64 && defined __aarch64__
    rc->ip = uc->Pc;      /* Program Counter */
    rc->fp = uc->Fp;      /* Frame Pointer (X29) */
    rc->sp = uc->Sp;      /* Stack Pointer (X30 is LR, but SP is separate) */
#elif defined _WIN64
    rc->ip = uc->Rip;
    rc->fp = uc->Rbp;
    rc->sp = uc->Rsp;
#elif defined _WIN32
    rc->ip = uc->Eip;
    rc->fp = uc->Ebp;
    rc->sp = uc->Esp;
#elif defined __i386__
# if defined(__APPLE__)
    rc->ip = uc->uc_mcontext->__ss.__eip;
    rc->fp = uc->uc_mcontext->__ss.__ebp;
# elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
    rc->ip = uc->uc_mcontext.mc_eip;
    rc->fp = uc->uc_mcontext.mc_ebp;
# elif defined(__dietlibc__)
    rc->ip = uc->uc_mcontext.eip;
    rc->fp = uc->uc_mcontext.ebp;
# elif defined(__NetBSD__)
    rc->ip = uc->uc_mcontext.__gregs[_REG_EIP];
    rc->fp = uc->uc_mcontext.__gregs[_REG_EBP];
# elif defined(__OpenBSD__)
    rc->ip = uc->sc_eip;
    rc->fp = uc->sc_ebp;
# elif !defined REG_EIP && defined EIP /* fix for glibc 2.1 */
    rc->ip = uc->uc_mcontext.gregs[EIP];
    rc->fp = uc->uc_mcontext.gregs[EBP];
# else
    rc->ip = uc->uc_mcontext.gregs[REG_EIP];
    rc->fp = uc->uc_mcontext.gregs[REG_EBP];
# endif
#elif defined(__x86_64__)
# if defined(__APPLE__)
    rc->ip = uc->uc_mcontext->__ss.__rip;
    rc->fp = uc->uc_mcontext->__ss.__rbp;
# elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
    rc->ip = uc->uc_mcontext.mc_rip;
    rc->fp = uc->uc_mcontext.mc_rbp;
# elif defined(__NetBSD__)
    rc->ip = uc->uc_mcontext.__gregs[_REG_RIP];
    rc->fp = uc->uc_mcontext.__gregs[_REG_RBP];
# elif defined(__OpenBSD__)
    rc->ip = uc->sc_rip;
    rc->fp = uc->sc_rbp;
# else
    rc->ip = uc->uc_mcontext.gregs[REG_RIP];
    rc->fp = uc->uc_mcontext.gregs[REG_RBP];
# endif
#elif defined(__arm__) && defined(__NetBSD__)
    rc->ip = uc->uc_mcontext.__gregs[_REG_PC];
    rc->fp = uc->uc_mcontext.__gregs[_REG_FP];
#elif defined(__arm__) && defined(__OpenBSD__)
    rc->ip = uc->sc_pc;
    rc->fp = uc->sc_r11;
#elif defined(__arm__) && defined(__FreeBSD__)
    rc->ip = uc->uc_mcontext.__gregs[_REG_PC];
    rc->fp = uc->uc_mcontext.__gregs[_REG_FP];
#elif defined(__arm__)
    rc->ip = uc->uc_mcontext.arm_pc;
    rc->fp = uc->uc_mcontext.arm_fp;
#elif defined(__aarch64__) && defined(__APPLE__)
    // see:
    // /Library/Developer/CommandLineTools/SDKs/MacOSX11.1.sdk/usr/include/mach/arm/_structs.h
    rc->ip = uc->uc_mcontext->__ss.__pc;
    rc->fp = uc->uc_mcontext->__ss.__fp;
#elif defined(__aarch64__) && defined(__FreeBSD__)
    rc->ip = uc->uc_mcontext.mc_gpregs.gp_elr; /* aka REG_PC */
    rc->fp = uc->uc_mcontext.mc_gpregs.gp_x[29];
#elif defined(__aarch64__) && defined(__NetBSD__)
    rc->ip = uc->uc_mcontext.__gregs[_REG_PC];
    rc->fp = uc->uc_mcontext.__gregs[_REG_FP];
#elif defined(__aarch64__) && defined(__OpenBSD__)
    rc->ip = uc->sc_elr;
    rc->fp = uc->sc_x[29];
#elif defined(__aarch64__)
    rc->ip = uc->uc_mcontext.pc;
    rc->fp = uc->uc_mcontext.regs[29];
#elif defined(__riscv) && defined(__OpenBSD__)
    rc->ip = uc->sc_sepc;
    rc->fp = uc->sc_s[0];
#elif defined(__riscv)
    rc->ip = uc->uc_mcontext.__gregs[REG_PC];
    rc->fp = uc->uc_mcontext.__gregs[REG_S0];
#endif
}

/* ------------------------------------------------------------- */
#ifndef _WIN32
/* signal handler for fatal errors */
static void sig_error(int signum, siginfo_t *siginf, void *puc)
{
    rt_frame f;
    rt_getcontext(puc, &f);

    switch(signum) {
    case SIGFPE:
        switch(siginf->si_code) {
        case FPE_INTDIV:
        case FPE_FLTDIV:
            rt_error(&f, "division by zero");
            break;
        default:
            rt_error(&f, "floating point exception");
            break;
        }
        break;
    case SIGBUS:
    case SIGSEGV:
        rt_error(&f, "invalid memory access");
        break;
    case SIGILL:
        rt_error(&f, "illegal instruction");
        break;
    case SIGABRT:
        rt_error(&f, "abort() called");
        break;
    default:
        rt_error(&f, "caught signal %d", signum);
        break;
    }
    {
        sigset_t s;
        sigemptyset(&s);
        sigaddset(&s, signum);
        sigprocmask(SIG_UNBLOCK, &s, NULL);
    }
    rt_exit(&f, 255);
}

#ifndef SA_SIGINFO
# define SA_SIGINFO 0x00000004u
#endif

/* Generate a stack backtrace when a CPU exception occurs. */
static void set_exception_handler(void)
{
    struct sigaction sigact;
    /* install TCC signal handlers to print debug info on fatal
       runtime errors */
    sigemptyset (&sigact.sa_mask);
    sigact.sa_flags = SA_SIGINFO; //| SA_RESETHAND;
#if 0//def SIGSTKSZ // this causes signals not to work at all on some (older) linuxes
    sigact.sa_flags |= SA_ONSTACK;
#endif
    sigact.sa_sigaction = sig_error;
    sigaction(SIGFPE, &sigact, NULL);
    sigaction(SIGILL, &sigact, NULL);
    sigaction(SIGSEGV, &sigact, NULL);
    sigaction(SIGBUS, &sigact, NULL);
    sigaction(SIGABRT, &sigact, NULL);
#if 0//def SIGSTKSZ
    /* This allows stack overflow to be reported instead of a SEGV */
    {
        stack_t ss;
        static unsigned char stack[SIGSTKSZ] __attribute__((aligned(16)));

        ss.ss_sp = stack;
        ss.ss_size = SIGSTKSZ;
        ss.ss_flags = 0;
        sigaltstack(&ss, NULL);
    }
#endif
}

#else /* WIN32 */

/* signal handler for fatal errors */
static long __stdcall cpu_exception_handler(EXCEPTION_POINTERS *ex_info)
{
    rt_frame f;
    unsigned code;
    rt_getcontext(ex_info->ContextRecord, &f);

    switch (code = ex_info->ExceptionRecord->ExceptionCode) {
    case EXCEPTION_ACCESS_VIOLATION:
	rt_error(&f, "invalid memory access");
        break;
    case EXCEPTION_STACK_OVERFLOW:
        rt_error(&f, "stack overflow");
        break;
    case EXCEPTION_INT_DIVIDE_BY_ZERO:
        rt_error(&f, "division by zero");
        break;
    case EXCEPTION_BREAKPOINT:
    case EXCEPTION_SINGLE_STEP:
        f.ip = *(addr_t*)f.sp;
        rt_error(&f, "breakpoint/single-step exception:");
        return EXCEPTION_CONTINUE_SEARCH;
    default:
        rt_error(&f, "caught exception %08x", code);
        break;
    }
    rt_exit(&f, 255);
    return EXCEPTION_EXECUTE_HANDLER;
}

/* Generate a stack backtrace when a CPU exception occurs. */
static void set_exception_handler(void)
{
#ifdef _WIN64
    AddVectoredExceptionHandler(1, cpu_exception_handler);
#else
    SetUnhandledExceptionFilter(cpu_exception_handler);
#endif
}

#endif

/* ------------------------------------------------------------- */
/* return the PC at frame level 'level'. Return negative if not found */
#if defined(__i386__) || defined(__x86_64__)
static int rt_get_caller_pc(addr_t *paddr, rt_frame *rc, int level)
{
    if (level == 0) {
        *paddr = rc->ip;
    } else {
        addr_t fp = rc->fp;
        while (1) {
            if (fp < 0x1000)
                return -1;
            if (0 == --level)
                break;
            /* XXX: check address validity with program info */
            fp = ((addr_t *)fp)[0];
        }
        *paddr = ((addr_t *)fp)[1];
    }
    return 0;
}

/* XXX: only supports linux/bsd */
#elif defined(__arm__) && !defined(_WIN32)
static int rt_get_caller_pc(addr_t *paddr, rt_frame *rc, int level)
{
    if (level == 0) {
        *paddr = rc->ip;
    } else {
        addr_t fp = rc->fp;
        while (1) {
            if (fp < 0x1000)
                return -1;
            if (0 == --level)
                break;
            fp = ((addr_t *)fp)[0];
        }
        *paddr = ((addr_t *)fp)[2];
    }
    return 0;
}

#elif defined(__aarch64__)
static int rt_get_caller_pc(addr_t *paddr, rt_frame *rc, int level)
{
    if (level == 0) {
        *paddr = rc->ip;
    } else {
        addr_t fp = rc->fp;
        while (1) {
            if (fp < 0x1000)
                return -1;
            if (0 == --level)
                break;
            fp = ((addr_t *)fp)[0];
        }
        *paddr = ((addr_t *)fp)[1];
    }
    return 0;
}

#elif defined(__riscv)
static int rt_get_caller_pc(addr_t *paddr, rt_frame *rc, int level)
{
    if (level == 0) {
        *paddr = rc->ip;
    } else {
        addr_t fp = rc->fp;
        while (1) {
            if (fp < 0x1000)
                return -1;
            if (0 == --level)
                break;
            fp = ((addr_t *)fp)[-2];
        }
        *paddr = ((addr_t *)fp)[-1];
    }
    return 0;
}

#else
#warning add arch specific rt_get_caller_pc()
static int rt_get_caller_pc(addr_t *paddr, rt_frame *rc, int level)
{
    return -1;
}

#endif
#else // for runmain.c:exit(); when CONFIG_TCC_BACKTRACE == 0 */
static int rt_get_caller_pc(addr_t *paddr, rt_frame *f, int level)
{
    if (level)
        return -1;
    *paddr = f->ip;
    return 0;
}
#endif /* CONFIG_TCC_BACKTRACE */
/* ------------------------------------------------------------- */
#ifdef CONFIG_TCC_STATIC

/* dummy function for profiling */
ST_FUNC void *dlopen(const char *filename, int flag)
{
    return NULL;
}

ST_FUNC void dlclose(void *p)
{
}

ST_FUNC const char *dlerror(void)
{
    return "error";
}

typedef struct TCCSyms {
    char *str;
    void *ptr;
} TCCSyms;


/* add the symbol you want here if no dynamic linking is done */
static TCCSyms tcc_syms[] = {
#if !defined(CONFIG_TCCBOOT)
#define TCCSYM(a) { #a, &a, },
    TCCSYM(printf)
    TCCSYM(fprintf)
    TCCSYM(fopen)
    TCCSYM(fclose)
#undef TCCSYM
#endif
    { NULL, NULL },
};

ST_FUNC void *dlsym(void *handle, const char *symbol)
{
    TCCSyms *p;
    p = tcc_syms;
    while (p->str != NULL) {
        if (!strcmp(p->str, symbol))
            return p->ptr;
        p++;
    }
    return NULL;
}

#endif /* CONFIG_TCC_STATIC */
#endif /* TCC_IS_NATIVE */
/* ------------------------------------------------------------- */