dwarf-aux.c

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/*
 * dwarf-aux.c : libdw auxiliary interfaces
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

#include <errno.h>
#include <inttypes.h>
#include <stdbool.h>
#include "util.h"
#include "debug.h"
#include "dwarf-aux.h"
#include "string2.h"

const char *cu_find_realpath(Dwarf_Die *cu_die, const char *fname)
{
    Dwarf_Files *files;
    size_t nfiles, i;
    const char *src = NULL;
    int ret;

    if (!fname)
        return NULL;

    ret = dwarf_getsrcfiles(cu_die, &files, &nfiles);
    if (ret != 0)
        return NULL;

    for (i = 0; i < nfiles; i++) {
        src = dwarf_filesrc(files, i, NULL, NULL);
        if (strtailcmp(src, fname) == 0)
            break;
    }
    if (i == nfiles)
        return NULL;
    return src;
}

const char *cu_get_comp_dir(Dwarf_Die *cu_die)
{
    Dwarf_Attribute attr;
    if (dwarf_attr(cu_die, DW_AT_comp_dir, &attr) == NULL)
        return NULL;
    return dwarf_formstring(&attr);
}

int cu_find_lineinfo(Dwarf_Die *cu_die, unsigned long addr,
            const char **fname, int *lineno)
{
    Dwarf_Line *line;
    Dwarf_Addr laddr;

    line = dwarf_getsrc_die(cu_die, (Dwarf_Addr)addr);
    if (line && dwarf_lineaddr(line, &laddr) == 0 &&
        addr == (unsigned long)laddr && dwarf_lineno(line, lineno) == 0) {
        *fname = dwarf_linesrc(line, NULL, NULL);
        if (!*fname)
            /* line number is useless without filename */
            *lineno = 0;
    }

    return *lineno ?: -ENOENT;
}

static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data);

int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,
            int (*callback)(Dwarf_Die *, void *), void *data)
{
    Dwarf_Die die_mem;
    Dwarf_Die *sc_die;
    int ret = -ENOENT;

    /* Inlined function could be recursive. Trace it until fail */
    for (sc_die = die_find_realfunc(cu_die, addr, &die_mem);
         sc_die != NULL;
         sc_die = die_find_child(sc_die, __die_find_inline_cb, &addr,
                     &die_mem)) {
        ret = callback(sc_die, data);
        if (ret)
            break;
    }

    return ret;

}

const char *die_get_linkage_name(Dwarf_Die *dw_die)
{
    Dwarf_Attribute attr;

    if (dwarf_attr_integrate(dw_die, DW_AT_linkage_name, &attr) == NULL)
        return NULL;
    return dwarf_formstring(&attr);
}

bool die_compare_name(Dwarf_Die *dw_die, const char *tname)
{
    const char *name;

    name = dwarf_diename(dw_die);
    return name ? (strcmp(tname, name) == 0) : false;
}

bool die_match_name(Dwarf_Die *dw_die, const char *glob)
{
    const char *name;

    name = dwarf_diename(dw_die);
    if (name && strglobmatch(name, glob))
        return true;
    /* fall back to check linkage name */
    name = die_get_linkage_name(dw_die);
    if (name && strglobmatch(name, glob))
        return true;

    return false;
}

int die_get_call_lineno(Dwarf_Die *in_die)
{
    Dwarf_Attribute attr;
    Dwarf_Word ret;

    if (!dwarf_attr(in_die, DW_AT_call_line, &attr))
        return -ENOENT;

    dwarf_formudata(&attr, &ret);
    return (int)ret;
}

Dwarf_Die *die_get_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
{
    Dwarf_Attribute attr;

    if (dwarf_attr_integrate(vr_die, DW_AT_type, &attr) &&
        dwarf_formref_die(&attr, die_mem))
        return die_mem;
    else
        return NULL;
}

/* Get a type die, but skip qualifiers */
static Dwarf_Die *__die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
{
    int tag;

    do {
        vr_die = die_get_type(vr_die, die_mem);
        if (!vr_die)
            break;
        tag = dwarf_tag(vr_die);
    } while (tag == DW_TAG_const_type ||
         tag == DW_TAG_restrict_type ||
         tag == DW_TAG_volatile_type ||
         tag == DW_TAG_shared_type);

    return vr_die;
}

Dwarf_Die *die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
{
    do {
        vr_die = __die_get_real_type(vr_die, die_mem);
    } while (vr_die && dwarf_tag(vr_die) == DW_TAG_typedef);

    return vr_die;
}

/* Get attribute and translate it as a udata */
static int die_get_attr_udata(Dwarf_Die *tp_die, unsigned int attr_name,
                  Dwarf_Word *result)
{
    Dwarf_Attribute attr;

    if (dwarf_attr(tp_die, attr_name, &attr) == NULL ||
        dwarf_formudata(&attr, result) != 0)
        return -ENOENT;

    return 0;
}

/* Get attribute and translate it as a sdata */
static int die_get_attr_sdata(Dwarf_Die *tp_die, unsigned int attr_name,
                  Dwarf_Sword *result)
{
    Dwarf_Attribute attr;

    if (dwarf_attr(tp_die, attr_name, &attr) == NULL ||
        dwarf_formsdata(&attr, result) != 0)
        return -ENOENT;

    return 0;
}

bool die_is_signed_type(Dwarf_Die *tp_die)
{
    Dwarf_Word ret;

    if (die_get_attr_udata(tp_die, DW_AT_encoding, &ret))
        return false;

    return (ret == DW_ATE_signed_char || ret == DW_ATE_signed ||
        ret == DW_ATE_signed_fixed);
}

bool die_is_func_def(Dwarf_Die *dw_die)
{
    Dwarf_Attribute attr;

    return (dwarf_tag(dw_die) == DW_TAG_subprogram &&
        dwarf_attr(dw_die, DW_AT_declaration, &attr) == NULL);
}

bool die_is_func_instance(Dwarf_Die *dw_die)
{
    Dwarf_Addr tmp;

    /* Actually gcc optimizes non-inline as like as inlined */
    return !dwarf_func_inline(dw_die) && dwarf_entrypc(dw_die, &tmp) == 0;
}
int die_get_data_member_location(Dwarf_Die *mb_die, Dwarf_Word *offs)
{
    Dwarf_Attribute attr;
    Dwarf_Op *expr;
    size_t nexpr;
    int ret;

    if (dwarf_attr(mb_die, DW_AT_data_member_location, &attr) == NULL)
        return -ENOENT;

    if (dwarf_formudata(&attr, offs) != 0) {
        /* DW_AT_data_member_location should be DW_OP_plus_uconst */
        ret = dwarf_getlocation(&attr, &expr, &nexpr);
        if (ret < 0 || nexpr == 0)
            return -ENOENT;

        if (expr[0].atom != DW_OP_plus_uconst || nexpr != 1) {
            pr_debug("Unable to get offset:Unexpected OP %x (%zd)\n",
                 expr[0].atom, nexpr);
            return -ENOTSUP;
        }
        *offs = (Dwarf_Word)expr[0].number;
    }
    return 0;
}

/* Get the call file index number in CU DIE */
static int die_get_call_fileno(Dwarf_Die *in_die)
{
    Dwarf_Sword idx;

    if (die_get_attr_sdata(in_die, DW_AT_call_file, &idx) == 0)
        return (int)idx;
    else
        return -ENOENT;
}

/* Get the declared file index number in CU DIE */
static int die_get_decl_fileno(Dwarf_Die *pdie)
{
    Dwarf_Sword idx;

    if (die_get_attr_sdata(pdie, DW_AT_decl_file, &idx) == 0)
        return (int)idx;
    else
        return -ENOENT;
}

const char *die_get_call_file(Dwarf_Die *in_die)
{
    Dwarf_Die cu_die;
    Dwarf_Files *files;
    int idx;

    idx = die_get_call_fileno(in_die);
    if (idx < 0 || !dwarf_diecu(in_die, &cu_die, NULL, NULL) ||
        dwarf_getsrcfiles(&cu_die, &files, NULL) != 0)
        return NULL;

    return dwarf_filesrc(files, idx, NULL, NULL);
}


Dwarf_Die *die_find_child(Dwarf_Die *rt_die,
              int (*callback)(Dwarf_Die *, void *),
              void *data, Dwarf_Die *die_mem)
{
    Dwarf_Die child_die;
    int ret;

    ret = dwarf_child(rt_die, die_mem);
    if (ret != 0)
        return NULL;

    do {
        ret = callback(die_mem, data);
        if (ret == DIE_FIND_CB_END)
            return die_mem;

        if ((ret & DIE_FIND_CB_CHILD) &&
            die_find_child(die_mem, callback, data, &child_die)) {
            memcpy(die_mem, &child_die, sizeof(Dwarf_Die));
            return die_mem;
        }
    } while ((ret & DIE_FIND_CB_SIBLING) &&
         dwarf_siblingof(die_mem, die_mem) == 0);

    return NULL;
}

struct __addr_die_search_param {
    Dwarf_Addr  addr;
    Dwarf_Die   *die_mem;
};

static int __die_search_func_tail_cb(Dwarf_Die *fn_die, void *data)
{
    struct __addr_die_search_param *ad = data;
    Dwarf_Addr addr = 0;

    if (dwarf_tag(fn_die) == DW_TAG_subprogram &&
        !dwarf_highpc(fn_die, &addr) &&
        addr == ad->addr) {
        memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die));
        return DWARF_CB_ABORT;
    }
    return DWARF_CB_OK;
}

Dwarf_Die *die_find_tailfunc(Dwarf_Die *cu_die, Dwarf_Addr addr,
                    Dwarf_Die *die_mem)
{
    struct __addr_die_search_param ad;
    ad.addr = addr;
    ad.die_mem = die_mem;
    /* dwarf_getscopes can't find subprogram. */
    if (!dwarf_getfuncs(cu_die, __die_search_func_tail_cb, &ad, 0))
        return NULL;
    else
        return die_mem;
}

/* die_find callback for non-inlined function search */
static int __die_search_func_cb(Dwarf_Die *fn_die, void *data)
{
    struct __addr_die_search_param *ad = data;

    /*
     * Since a declaration entry doesn't has given pc, this always returns
     * function definition entry.
     */
    if (dwarf_tag(fn_die) == DW_TAG_subprogram &&
        dwarf_haspc(fn_die, ad->addr)) {
        memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die));
        return DWARF_CB_ABORT;
    }
    return DWARF_CB_OK;
}

Dwarf_Die *die_find_realfunc(Dwarf_Die *cu_die, Dwarf_Addr addr,
                    Dwarf_Die *die_mem)
{
    struct __addr_die_search_param ad;
    ad.addr = addr;
    ad.die_mem = die_mem;
    /* dwarf_getscopes can't find subprogram. */
    if (!dwarf_getfuncs(cu_die, __die_search_func_cb, &ad, 0))
        return NULL;
    else
        return die_mem;
}

/* die_find callback for inline function search */
static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data)
{
    Dwarf_Addr *addr = data;

    if (dwarf_tag(die_mem) == DW_TAG_inlined_subroutine &&
        dwarf_haspc(die_mem, *addr))
        return DIE_FIND_CB_END;

    return DIE_FIND_CB_CONTINUE;
}

Dwarf_Die *die_find_top_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
                   Dwarf_Die *die_mem)
{
    return die_find_child(sp_die, __die_find_inline_cb, &addr, die_mem);
}

Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
                   Dwarf_Die *die_mem)
{
    Dwarf_Die tmp_die;

    sp_die = die_find_child(sp_die, __die_find_inline_cb, &addr, &tmp_die);
    if (!sp_die)
        return NULL;

    /* Inlined function could be recursive. Trace it until fail */
    while (sp_die) {
        memcpy(die_mem, sp_die, sizeof(Dwarf_Die));
        sp_die = die_find_child(sp_die, __die_find_inline_cb, &addr,
                    &tmp_die);
    }

    return die_mem;
}

struct __instance_walk_param {
    void    *addr;
    int (*callback)(Dwarf_Die *, void *);
    void    *data;
    int retval;
};

static int __die_walk_instances_cb(Dwarf_Die *inst, void *data)
{
    struct __instance_walk_param *iwp = data;
    Dwarf_Attribute attr_mem;
    Dwarf_Die origin_mem;
    Dwarf_Attribute *attr;
    Dwarf_Die *origin;
    int tmp;

    attr = dwarf_attr(inst, DW_AT_abstract_origin, &attr_mem);
    if (attr == NULL)
        return DIE_FIND_CB_CONTINUE;

    origin = dwarf_formref_die(attr, &origin_mem);
    if (origin == NULL || origin->addr != iwp->addr)
        return DIE_FIND_CB_CONTINUE;

    /* Ignore redundant instances */
    if (dwarf_tag(inst) == DW_TAG_inlined_subroutine) {
        dwarf_decl_line(origin, &tmp);
        if (die_get_call_lineno(inst) == tmp) {
            tmp = die_get_decl_fileno(origin);
            if (die_get_call_fileno(inst) == tmp)
                return DIE_FIND_CB_CONTINUE;
        }
    }

    iwp->retval = iwp->callback(inst, iwp->data);

    return (iwp->retval) ? DIE_FIND_CB_END : DIE_FIND_CB_CONTINUE;
}

int die_walk_instances(Dwarf_Die *or_die, int (*callback)(Dwarf_Die *, void *),
               void *data)
{
    Dwarf_Die cu_die;
    Dwarf_Die die_mem;
    struct __instance_walk_param iwp = {
        .addr = or_die->addr,
        .callback = callback,
        .data = data,
        .retval = -ENOENT,
    };

    if (dwarf_diecu(or_die, &cu_die, NULL, NULL) == NULL)
        return -ENOENT;

    die_find_child(&cu_die, __die_walk_instances_cb, &iwp, &die_mem);

    return iwp.retval;
}

/* Line walker internal parameters */
struct __line_walk_param {
    bool recursive;
    line_walk_callback_t callback;
    void *data;
    int retval;
};

static int __die_walk_funclines_cb(Dwarf_Die *in_die, void *data)
{
    struct __line_walk_param *lw = data;
    Dwarf_Addr addr = 0;
    const char *fname;
    int lineno;

    if (dwarf_tag(in_die) == DW_TAG_inlined_subroutine) {
        fname = die_get_call_file(in_die);
        lineno = die_get_call_lineno(in_die);
        if (fname && lineno > 0 && dwarf_entrypc(in_die, &addr) == 0) {
            lw->retval = lw->callback(fname, lineno, addr, lw->data);
            if (lw->retval != 0)
                return DIE_FIND_CB_END;
        }
    }
    if (!lw->recursive)
        /* Don't need to search recursively */
        return DIE_FIND_CB_SIBLING;

    if (addr) {
        fname = dwarf_decl_file(in_die);
        if (fname && dwarf_decl_line(in_die, &lineno) == 0) {
            lw->retval = lw->callback(fname, lineno, addr, lw->data);
            if (lw->retval != 0)
                return DIE_FIND_CB_END;
        }
    }

    /* Continue to search nested inlined function call-sites */
    return DIE_FIND_CB_CONTINUE;
}

/* Walk on lines of blocks included in given DIE */
static int __die_walk_funclines(Dwarf_Die *sp_die, bool recursive,
                line_walk_callback_t callback, void *data)
{
    struct __line_walk_param lw = {
        .recursive = recursive,
        .callback = callback,
        .data = data,
        .retval = 0,
    };
    Dwarf_Die die_mem;
    Dwarf_Addr addr;
    const char *fname;
    int lineno;

    /* Handle function declaration line */
    fname = dwarf_decl_file(sp_die);
    if (fname && dwarf_decl_line(sp_die, &lineno) == 0 &&
        dwarf_entrypc(sp_die, &addr) == 0) {
        lw.retval = callback(fname, lineno, addr, data);
        if (lw.retval != 0)
            goto done;
    }
    die_find_child(sp_die, __die_walk_funclines_cb, &lw, &die_mem);
done:
    return lw.retval;
}

static int __die_walk_culines_cb(Dwarf_Die *sp_die, void *data)
{
    struct __line_walk_param *lw = data;

    lw->retval = __die_walk_funclines(sp_die, true, lw->callback, lw->data);
    if (lw->retval != 0)
        return DWARF_CB_ABORT;

    return DWARF_CB_OK;
}

int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
{
    Dwarf_Lines *lines;
    Dwarf_Line *line;
    Dwarf_Addr addr;
    const char *fname, *decf = NULL;
    int lineno, ret = 0;
    int decl = 0, inl;
    Dwarf_Die die_mem, *cu_die;
    size_t nlines, i;

    /* Get the CU die */
    if (dwarf_tag(rt_die) != DW_TAG_compile_unit) {
        cu_die = dwarf_diecu(rt_die, &die_mem, NULL, NULL);
        dwarf_decl_line(rt_die, &decl);
        decf = dwarf_decl_file(rt_die);
    } else
        cu_die = rt_die;
    if (!cu_die) {
        pr_debug2("Failed to get CU from given DIE.\n");
        return -EINVAL;
    }

    /* Get lines list in the CU */
    if (dwarf_getsrclines(cu_die, &lines, &nlines) != 0) {
        pr_debug2("Failed to get source lines on this CU.\n");
        return -ENOENT;
    }
    pr_debug2("Get %zd lines from this CU\n", nlines);

    /* Walk on the lines on lines list */
    for (i = 0; i < nlines; i++) {
        line = dwarf_onesrcline(lines, i);
        if (line == NULL ||
            dwarf_lineno(line, &lineno) != 0 ||
            dwarf_lineaddr(line, &addr) != 0) {
            pr_debug2("Failed to get line info. "
                  "Possible error in debuginfo.\n");
            continue;
        }
        /* Filter lines based on address */
        if (rt_die != cu_die) {
            /*
             * Address filtering
             * The line is included in given function, and
             * no inline block includes it.
             */
            if (!dwarf_haspc(rt_die, addr))
                continue;
            if (die_find_inlinefunc(rt_die, addr, &die_mem)) {
                dwarf_decl_line(&die_mem, &inl);
                if (inl != decl ||
                    decf != dwarf_decl_file(&die_mem))
                    continue;
            }
        }
        /* Get source line */
        fname = dwarf_linesrc(line, NULL, NULL);

        ret = callback(fname, lineno, addr, data);
        if (ret != 0)
            return ret;
    }

    /*
     * Dwarf lines doesn't include function declarations and inlined
     * subroutines. We have to check functions list or given function.
     */
    if (rt_die != cu_die)
        /*
         * Don't need walk functions recursively, because nested
         * inlined functions don't have lines of the specified DIE.
         */
        ret = __die_walk_funclines(rt_die, false, callback, data);
    else {
        struct __line_walk_param param = {
            .callback = callback,
            .data = data,
            .retval = 0,
        };
        dwarf_getfuncs(cu_die, __die_walk_culines_cb, &param, 0);
        ret = param.retval;
    }

    return ret;
}

struct __find_variable_param {
    const char *name;
    Dwarf_Addr addr;
};

static int __die_find_variable_cb(Dwarf_Die *die_mem, void *data)
{
    struct __find_variable_param *fvp = data;
    Dwarf_Attribute attr;
    int tag;

    tag = dwarf_tag(die_mem);
    if ((tag == DW_TAG_formal_parameter ||
         tag == DW_TAG_variable) &&
        die_compare_name(die_mem, fvp->name) &&
    /* Does the DIE have location information or external instance? */
        (dwarf_attr(die_mem, DW_AT_external, &attr) ||
         dwarf_attr(die_mem, DW_AT_location, &attr)))
        return DIE_FIND_CB_END;
    if (dwarf_haspc(die_mem, fvp->addr))
        return DIE_FIND_CB_CONTINUE;
    else
        return DIE_FIND_CB_SIBLING;
}

Dwarf_Die *die_find_variable_at(Dwarf_Die *sp_die, const char *name,
                Dwarf_Addr addr, Dwarf_Die *die_mem)
{
    struct __find_variable_param fvp = { .name = name, .addr = addr};

    return die_find_child(sp_die, __die_find_variable_cb, (void *)&fvp,
                  die_mem);
}

static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)
{
    const char *name = data;

    if (dwarf_tag(die_mem) == DW_TAG_member) {
        if (die_compare_name(die_mem, name))
            return DIE_FIND_CB_END;
        else if (!dwarf_diename(die_mem)) { /* Unnamed structure */
            Dwarf_Die type_die, tmp_die;
            if (die_get_type(die_mem, &type_die) &&
                die_find_member(&type_die, name, &tmp_die))
                return DIE_FIND_CB_END;
        }
    }
    return DIE_FIND_CB_SIBLING;
}

Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,
               Dwarf_Die *die_mem)
{
    return die_find_child(st_die, __die_find_member_cb, (void *)name,
                  die_mem);
}

int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf)
{
    Dwarf_Die type;
    int tag, ret;
    const char *tmp = "";

    if (__die_get_real_type(vr_die, &type) == NULL)
        return -ENOENT;

    tag = dwarf_tag(&type);
    if (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)
        tmp = "*";
    else if (tag == DW_TAG_subroutine_type) {
        /* Function pointer */
        return strbuf_add(buf, "(function_type)", 15);
    } else {
        if (!dwarf_diename(&type))
            return -ENOENT;
        if (tag == DW_TAG_union_type)
            tmp = "union ";
        else if (tag == DW_TAG_structure_type)
            tmp = "struct ";
        else if (tag == DW_TAG_enumeration_type)
            tmp = "enum ";
        /* Write a base name */
        return strbuf_addf(buf, "%s%s", tmp, dwarf_diename(&type));
    }
    ret = die_get_typename(&type, buf);
    return ret ? ret : strbuf_addstr(buf, tmp);
}

int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf)
{
    int ret;

    ret = die_get_typename(vr_die, buf);
    if (ret < 0) {
        pr_debug("Failed to get type, make it unknown.\n");
        ret = strbuf_add(buf, " (unknown_type)", 14);
    }

    return ret < 0 ? ret : strbuf_addf(buf, "\t%s", dwarf_diename(vr_die));
}

#ifdef HAVE_DWARF_GETLOCATIONS_SUPPORT

static int die_get_var_innermost_scope(Dwarf_Die *sp_die, Dwarf_Die *vr_die,
                struct strbuf *buf)
{
    Dwarf_Die *scopes;
    int count;
    size_t offset = 0;
    Dwarf_Addr base;
    Dwarf_Addr start, end;
    Dwarf_Addr entry;
    int ret;
    bool first = true;
    const char *name;

    ret = dwarf_entrypc(sp_die, &entry);
    if (ret)
        return ret;

    name = dwarf_diename(sp_die);
    if (!name)
        return -ENOENT;

    count = dwarf_getscopes_die(vr_die, &scopes);

    /* (*SCOPES)[1] is the DIE for the scope containing that scope */
    if (count <= 1) {
        ret = -EINVAL;
        goto out;
    }

    while ((offset = dwarf_ranges(&scopes[1], offset, &base,
                    &start, &end)) > 0) {
        start -= entry;
        end -= entry;

        if (first) {
            ret = strbuf_addf(buf, "@<%s+[%" PRIu64 "-%" PRIu64,
                      name, start, end);
            first = false;
        } else {
            ret = strbuf_addf(buf, ",%" PRIu64 "-%" PRIu64,
                      start, end);
        }
        if (ret < 0)
            goto out;
    }

    if (!first)
        ret = strbuf_add(buf, "]>", 2);

out:
    free(scopes);
    return ret;
}

int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf)
{
    int ret = 0;
    Dwarf_Addr base;
    Dwarf_Addr start, end;
    Dwarf_Addr entry;
    Dwarf_Op *op;
    size_t nops;
    size_t offset = 0;
    Dwarf_Attribute attr;
    bool first = true;
    const char *name;

    ret = dwarf_entrypc(sp_die, &entry);
    if (ret)
        return ret;

    name = dwarf_diename(sp_die);
    if (!name)
        return -ENOENT;

    if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
        return -EINVAL;

    while ((offset = dwarf_getlocations(&attr, offset, &base,
                    &start, &end, &op, &nops)) > 0) {
        if (start == 0) {
            /* Single Location Descriptions */
            ret = die_get_var_innermost_scope(sp_die, vr_die, buf);
            goto out;
        }

        /* Location Lists */
        start -= entry;
        end -= entry;
        if (first) {
            ret = strbuf_addf(buf, "@<%s+[%" PRIu64 "-%" PRIu64,
                      name, start, end);
            first = false;
        } else {
            ret = strbuf_addf(buf, ",%" PRIu64 "-%" PRIu64,
                      start, end);
        }
        if (ret < 0)
            goto out;
    }

    if (!first)
        ret = strbuf_add(buf, "]>", 2);
out:
    return ret;
}
#else
int die_get_var_range(Dwarf_Die *sp_die __maybe_unused,
              Dwarf_Die *vr_die __maybe_unused,
              struct strbuf *buf __maybe_unused)
{
    return -ENOTSUP;
}
#endif

/*
 * die_has_loclist - Check if DW_AT_location of @vr_die is a location list
 * @vr_die: a variable DIE
 */
static bool die_has_loclist(Dwarf_Die *vr_die)
{
    Dwarf_Attribute loc;
    int tag = dwarf_tag(vr_die);

    if (tag != DW_TAG_formal_parameter &&
        tag != DW_TAG_variable)
        return false;

    return (dwarf_attr_integrate(vr_die, DW_AT_location, &loc) &&
        dwarf_whatform(&loc) == DW_FORM_sec_offset);
}

/*
 * die_is_optimized_target - Check if target program is compiled with
 * optimization
 * @cu_die: a CU DIE
 *
 * For any object in given CU whose DW_AT_location is a location list,
 * target program is compiled with optimization. This is applicable to
 * clang as well.
 */
bool die_is_optimized_target(Dwarf_Die *cu_die)
{
    Dwarf_Die tmp_die;

    if (die_has_loclist(cu_die))
        return true;

    if (!dwarf_child(cu_die, &tmp_die) &&
        die_is_optimized_target(&tmp_die))
        return true;

    if (!dwarf_siblingof(cu_die, &tmp_die) &&
        die_is_optimized_target(&tmp_die))
        return true;

    return false;
}

/*
 * die_search_idx - Search index of given line address
 * @lines: Line records of single CU
 * @nr_lines: Number of @lines
 * @addr: address we are looking for
 * @idx: index to be set by this function (return value)
 *
 * Search for @addr by looping over every lines of CU. If address
 * matches, set index of that line in @idx. Note that single source
 * line can have multiple line records. i.e. single source line can
 * have multiple index.
 */
static bool die_search_idx(Dwarf_Lines *lines, unsigned long nr_lines,
               Dwarf_Addr addr, unsigned long *idx)
{
    unsigned long i;
    Dwarf_Addr tmp;

    for (i = 0; i < nr_lines; i++) {
        if (dwarf_lineaddr(dwarf_onesrcline(lines, i), &tmp))
            return false;

        if (tmp == addr) {
            *idx = i;
            return true;
        }
    }
    return false;
}

/*
 * die_get_postprologue_addr - Search next address after function prologue
 * @entrypc_idx: entrypc index
 * @lines: Line records of single CU
 * @nr_lines: Number of @lines
 * @hignpc: high PC address of function
 * @postprologue_addr: Next address after function prologue (return value)
 *
 * Look for prologue-end marker. If there is no explicit marker, return
 * address of next line record or next source line.
 */
static bool die_get_postprologue_addr(unsigned long entrypc_idx,
                      Dwarf_Lines *lines,
                      unsigned long nr_lines,
                      Dwarf_Addr highpc,
                      Dwarf_Addr *postprologue_addr)
{
    unsigned long i;
    int entrypc_lno, lno;
    Dwarf_Line *line;
    Dwarf_Addr addr;
    bool p_end;

    /* entrypc_lno is actual source line number */
    line = dwarf_onesrcline(lines, entrypc_idx);
    if (dwarf_lineno(line, &entrypc_lno))
        return false;

    for (i = entrypc_idx; i < nr_lines; i++) {
        line = dwarf_onesrcline(lines, i);

        if (dwarf_lineaddr(line, &addr) ||
            dwarf_lineno(line, &lno)    ||
            dwarf_lineprologueend(line, &p_end))
            return false;

        /* highpc is exclusive. [entrypc,highpc) */
        if (addr >= highpc)
            break;

        /* clang supports prologue-end marker */
        if (p_end)
            break;

        /* Actual next line in source */
        if (lno != entrypc_lno)
            break;

        /*
         * Single source line can have multiple line records.
         * For Example,
         *     void foo() { printf("hello\n"); }
         * contains two line records. One points to declaration and
         * other points to printf() line. Variable 'lno' won't get
         * incremented in this case but 'i' will.
         */
        if (i != entrypc_idx)
            break;
    }

    dwarf_lineaddr(line, postprologue_addr);
    if (*postprologue_addr >= highpc)
        dwarf_lineaddr(dwarf_onesrcline(lines, i - 1),
                   postprologue_addr);

    return true;
}

/*
 * die_skip_prologue - Use next address after prologue as probe location
 * @sp_die: a subprogram DIE
 * @cu_die: a CU DIE
 * @entrypc: entrypc of the function
 *
 * Function prologue prepares stack and registers before executing function
 * logic. When target program is compiled without optimization, function
 * parameter information is only valid after prologue. When we probe entrypc
 * of the function, and try to record function parameter, it contains
 * garbage value.
 */
void die_skip_prologue(Dwarf_Die *sp_die, Dwarf_Die *cu_die,
               Dwarf_Addr *entrypc)
{
    size_t nr_lines = 0;
    unsigned long entrypc_idx = 0;
    Dwarf_Lines *lines = NULL;
    Dwarf_Addr postprologue_addr;
    Dwarf_Addr highpc;

    if (dwarf_highpc(sp_die, &highpc))
        return;

    if (dwarf_getsrclines(cu_die, &lines, &nr_lines))
        return;

    if (!die_search_idx(lines, nr_lines, *entrypc, &entrypc_idx))
        return;

    if (!die_get_postprologue_addr(entrypc_idx, lines, nr_lines,
                       highpc, &postprologue_addr))
        return;

    *entrypc = postprologue_addr;
}