ctf/cvt/dwarf.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Copyright 2012 Jason King.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * DWARF to tdata conversion
 *
 * For the most part, conversion is straightforward, proceeding in two passes.
 * On the first pass, we iterate through every die, creating new type nodes as
 * necessary.  Referenced tdesc_t's are created in an uninitialized state, thus
 * allowing type reference pointers to be filled in.  If the tdesc_t
 * corresponding to a given die can be completely filled out (sizes and offsets
 * calculated, and so forth) without using any referenced types, the tdesc_t is
 * marked as resolved.  Consider an array type.  If the type corresponding to
 * the array contents has not yet been processed, we will create a blank tdesc
 * for the contents type (only the type ID will be filled in, relying upon the
 * later portion of the first pass to encounter and complete the referenced
 * type).  We will then attempt to determine the size of the array.  If the
 * array has a byte size attribute, we will have completely characterized the
 * array type, and will be able to mark it as resolved.  The lack of a byte
 * size attribute, on the other hand, will prevent us from fully resolving the
 * type, as the size will only be calculable with reference to the contents
 * type, which has not, as yet, been encountered.  The array type will thus be
 * left without the resolved flag, and the first pass will continue.
 *
 * When we begin the second pass, we will have created tdesc_t nodes for every
 * type in the section.  We will traverse the tree, from the iidescs down,
 * processing each unresolved node.  As the referenced nodes will have been
 * populated, the array type used in our example above will be able to use the
 * size of the referenced types (if available) to determine its own type.  The
 * traversal will be repeated until all types have been resolved or we have
 * failed to make progress.  When all tdescs have been resolved, the conversion
 * is complete.
 *
 * There are, as always, a few special cases that are handled during the first
 * and second passes:
 *
 *  1. Empty enums - GCC will occasionally emit an enum without any members.
 *     Later on in the file, it will emit the same enum type, though this time
 *     with the full complement of members.  All references to the memberless
 *     enum need to be redirected to the full definition.  During the first
 *     pass, each enum is entered in dm_enumhash, along with a pointer to its
 *     corresponding tdesc_t.  If, during the second pass, we encounter a
 *     memberless enum, we use the hash to locate the full definition.  All
 *     tdescs referencing the empty enum are then redirected.
 *
 *  2. Forward declarations - If the compiler sees a forward declaration for
 *     a structure, followed by the definition of that structure, it will emit
 *     DWARF data for both the forward declaration and the definition.  We need
 *     to resolve the forward declarations when possible, by redirecting
 *     forward-referencing tdescs to the actual struct/union definitions.  This
 *     redirection is done completely within the first pass.  We begin by
 *     recording all forward declarations in dw_fwdhash.  When we define a
 *     structure, we check to see if there have been any corresponding forward
 *     declarations.  If so, we redirect the tdescs which referenced the forward
 *     declarations to the structure or union definition.
 *
 * XXX see if a post traverser will allow the elimination of repeated pass 2
 * traversals.
 */

#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <errno.h>
#include <libelf.h>
#include <libdwarf.h>
#include <libgen.h>
#include <dwarf.h>

#include "ctf_headers.h"
#include "ctftools.h"
#include "memory.h"
#include "list.h"
#include "traverse.h"

/* The version of DWARF which we support. */
#define DWARF_VERSION   2

/*
 * We need to define a couple of our own intrinsics, to smooth out some of the
 * differences between the GCC and DevPro DWARF emitters.  See the referenced
 * routines and the special cases in the file comment for more details.
 *
 * Type IDs are 32 bits wide.  We're going to use the top of that field to
 * indicate types that we've created ourselves.
 */
#define TID_FILEMAX     0x3fffffff  /* highest tid from file */
#define TID_VOID        0x40000001  /* see die_void() */
#define TID_LONG        0x40000002  /* see die_array() */

#define TID_MFGTID_BASE     0x40000003  /* first mfg'd tid */

/*
 * To reduce the staggering amount of error-handling code that would otherwise
 * be required, the attribute-retrieval routines handle most of their own
 * errors.  If the following flag is supplied as the value of the `req'
 * argument, they will also handle the absence of a requested attribute by
 * terminating the program.
 */
#define DW_ATTR_REQ 1

#define TDESC_HASH_BUCKETS  511

typedef struct dwarf {
    Dwarf_Debug dw_dw;      /* for libdwarf */
    Dwarf_Error dw_err;     /* for libdwarf */
    Dwarf_Unsigned dw_maxoff;   /* highest legal offset in this cu */
    tdata_t *dw_td;         /* root of the tdesc/iidesc tree */
    hash_t *dw_tidhash;     /* hash of tdescs by t_id */
    hash_t *dw_fwdhash;     /* hash of fwd decls by name */
    hash_t *dw_enumhash;        /* hash of memberless enums by name */
    tdesc_t *dw_void;       /* manufactured void type */
    tdesc_t *dw_long;       /* manufactured long type for arrays */
    size_t dw_ptrsz;        /* size of a pointer in this file */
    tid_t dw_mfgtid_last;       /* last mfg'd type ID used */
    uint_t dw_nunres;       /* count of unresolved types */
    char *dw_cuname;        /* name of compilation unit */
} dwarf_t;

static void die_create_one(dwarf_t *, Dwarf_Die);
static void die_create(dwarf_t *, Dwarf_Die);

static tid_t
mfgtid_next(dwarf_t *dw)
{
    return (++dw->dw_mfgtid_last);
}

static void
tdesc_add(dwarf_t *dw, tdesc_t *tdp)
{
    hash_add(dw->dw_tidhash, tdp);
}

static tdesc_t *
tdesc_lookup(dwarf_t *dw, int tid)
{
    tdesc_t tmpl, *tdp;

    tmpl.t_id = tid;

    if (hash_find(dw->dw_tidhash, &tmpl, (void **)&tdp))
        return (tdp);
    else
        return (NULL);
}

/*
 * Resolve a tdesc down to a node which should have a size.  Returns the size,
 * zero if the size hasn't yet been determined.
 */
static size_t
tdesc_size(tdesc_t *tdp)
{
    for (;;) {
        switch (tdp->t_type) {
        case INTRINSIC:
        case POINTER:
        case ARRAY:
        case FUNCTION:
        case STRUCT:
        case UNION:
        case ENUM:
            return (tdp->t_size);

        case FORWARD:
            return (0);

        case TYPEDEF:
        case VOLATILE:
        case CONST:
        case RESTRICT:
            tdp = tdp->t_tdesc;
            continue;

        case 0: /* not yet defined */
            return (0);

        default:
            terminate("tdp %u: tdesc_size on unknown type %d\n",
                tdp->t_id, tdp->t_type);
        }
    }
}

static size_t
tdesc_bitsize(tdesc_t *tdp)
{
    for (;;) {
        switch (tdp->t_type) {
        case INTRINSIC:
            return (tdp->t_intr->intr_nbits);

        case ARRAY:
        case FUNCTION:
        case STRUCT:
        case UNION:
        case ENUM:
        case POINTER:
            return (tdp->t_size * NBBY);

        case FORWARD:
            return (0);

        case TYPEDEF:
        case VOLATILE:
        case RESTRICT:
        case CONST:
            tdp = tdp->t_tdesc;
            continue;

        case 0: /* not yet defined */
            return (0);

        default:
            terminate("tdp %u: tdesc_bitsize on unknown type %d\n",
                tdp->t_id, tdp->t_type);
        }
    }
}

static tdesc_t *
tdesc_basetype(tdesc_t *tdp)
{
    for (;;) {
        switch (tdp->t_type) {
        case TYPEDEF:
        case VOLATILE:
        case RESTRICT:
        case CONST:
            tdp = tdp->t_tdesc;
            break;
        case 0: /* not yet defined */
            return (NULL);
        default:
            return (tdp);
        }
    }
}

static Dwarf_Off
die_off(dwarf_t *dw, Dwarf_Die die)
{
    Dwarf_Off off;

    if (dwarf_dieoffset(die, &off, &dw->dw_err) == DW_DLV_OK)
        return (off);

    terminate("failed to get offset for die: %s\n",
        dwarf_errmsg(dw->dw_err));
    /*NOTREACHED*/
    return (0);
}

static Dwarf_Die
die_sibling(dwarf_t *dw, Dwarf_Die die)
{
    Dwarf_Die sib;
    int rc;

    if ((rc = dwarf_siblingof(dw->dw_dw, die, &sib, &dw->dw_err)) ==
        DW_DLV_OK)
        return (sib);
    else if (rc == DW_DLV_NO_ENTRY)
        return (NULL);

    terminate("die %llu: failed to find type sibling: %s\n",
        die_off(dw, die), dwarf_errmsg(dw->dw_err));
    /*NOTREACHED*/
    return (NULL);
}

static Dwarf_Die
die_child(dwarf_t *dw, Dwarf_Die die)
{
    Dwarf_Die child;
    int rc;

    if ((rc = dwarf_child(die, &child, &dw->dw_err)) == DW_DLV_OK)
        return (child);
    else if (rc == DW_DLV_NO_ENTRY)
        return (NULL);

    terminate("die %llu: failed to find type child: %s\n",
        die_off(dw, die), dwarf_errmsg(dw->dw_err));
    /*NOTREACHED*/
    return (NULL);
}

static Dwarf_Half
die_tag(dwarf_t *dw, Dwarf_Die die)
{
    Dwarf_Half tag;

    if (dwarf_tag(die, &tag, &dw->dw_err) == DW_DLV_OK)
        return (tag);

    terminate("die %llu: failed to get tag for type: %s\n",
        die_off(dw, die), dwarf_errmsg(dw->dw_err));
    /*NOTREACHED*/
    return (0);
}

static Dwarf_Attribute
die_attr(dwarf_t *dw, Dwarf_Die die, Dwarf_Half name, int req)
{
    Dwarf_Attribute attr;
    int rc;

    if ((rc = dwarf_attr(die, name, &attr, &dw->dw_err)) == DW_DLV_OK) {
        return (attr);
    } else if (rc == DW_DLV_NO_ENTRY) {
        if (req) {
            terminate("die %llu: no attr 0x%x\n", die_off(dw, die),
                name);
        } else {
            return (NULL);
        }
    }

    terminate("die %llu: failed to get attribute for type: %s\n",
        die_off(dw, die), dwarf_errmsg(dw->dw_err));
    /*NOTREACHED*/
    return (NULL);
}

static Dwarf_Half
die_attr_form(dwarf_t *dw, Dwarf_Attribute attr)
{
    Dwarf_Half form;

    if (dwarf_whatform(attr, &form, &dw->dw_err) == DW_DLV_OK)
        return (form);

    terminate("failed to get attribute form for type: %s\n",
        dwarf_errmsg(dw->dw_err));
    /*NOTREACHED*/
    return (0);
}

/*
 * the following functions lookup the value of an attribute in a DIE:
 *
 * die_signed
 * die_unsigned
 * die_bool
 * die_string
 *
 * They all take the same parameters (with the exception of valp which is
 * a pointer to the type of the attribute we are looking up):
 *
 * dw - the dwarf object to look in
 * die - the DIE we're interested in
 * name - the name of the attribute to lookup
 * valp - pointer to where the value of the attribute is placed
 * req - if the value is required (0 / non-zero)
 *
 * If the attribute is not found, one of the following happens:
 * - program terminates (req is non-zero)
 * - function returns 0
 *
 * If the value is found, and in a form (class) we can handle, the function
 * returns 1.
 *
 * Currently, we can only handle attribute values that are stored as
 * constants (immediate value).  If an attribute has a form we cannot
 * handle (for example VLAs may store the dimensions of the array
 * as a DWARF expression that can compute it at runtime by reading
 * values off the stack or other locations in memory), it is treated
 * the same as if the attribute does not exist.
 */
static int
die_signed(dwarf_t *dw, Dwarf_Die die, Dwarf_Half name, Dwarf_Signed *valp,
    int req)
{
    Dwarf_Attribute attr;
    Dwarf_Signed val;

    if ((attr = die_attr(dw, die, name, req)) == NULL)
        return (0); /* die_attr will terminate for us if necessary */

    if (dwarf_formsdata(attr, &val, &dw->dw_err) != DW_DLV_OK) {
        if (req == 0)
            return (0);

        terminate("die %llu: failed to get signed (form 0x%x)\n",
            die_off(dw, die), die_attr_form(dw, attr));
    }

    dwarf_dealloc(dw->dw_dw, attr, DW_DLA_ATTR);

    *valp = val;
    return (1);
}

static int
die_unsigned(dwarf_t *dw, Dwarf_Die die, Dwarf_Half name, Dwarf_Unsigned *valp,
    int req)
{
    Dwarf_Attribute attr;
    Dwarf_Unsigned val;

    if ((attr = die_attr(dw, die, name, req)) == NULL)
        return (0); /* die_attr will terminate for us if necessary */

    if (dwarf_formudata(attr, &val, &dw->dw_err) != DW_DLV_OK) {
        if (req == 0)
            return (0);

        terminate("die %llu: failed to get unsigned (form 0x%x)\n",
            die_off(dw, die), die_attr_form(dw, attr));
    }

    dwarf_dealloc(dw->dw_dw, attr, DW_DLA_ATTR);

    *valp = val;
    return (1);
}

static int
die_bool(dwarf_t *dw, Dwarf_Die die, Dwarf_Half name, Dwarf_Bool *valp, int req)
{
    Dwarf_Attribute attr;
    Dwarf_Bool val;

    if ((attr = die_attr(dw, die, name, req)) == NULL)
        return (0); /* die_attr will terminate for us if necessary */

    if (dwarf_formflag(attr, &val, &dw->dw_err) != DW_DLV_OK) {
        if (req == 0)
            return (0);

        terminate("die %llu: failed to get bool (form 0x%x)\n",
            die_off(dw, die), die_attr_form(dw, attr));
    }

    dwarf_dealloc(dw->dw_dw, attr, DW_DLA_ATTR);

    *valp = val;
    return (1);
}

static int
die_string(dwarf_t *dw, Dwarf_Die die, Dwarf_Half name, char **strp, int req)
{
    Dwarf_Attribute attr;
    char *str;

    if ((attr = die_attr(dw, die, name, req)) == NULL)
        return (0); /* die_attr will terminate for us if necessary */

    if (dwarf_formstring(attr, &str, &dw->dw_err) != DW_DLV_OK) {
        if (req == 0)
            return (0);

        terminate("die %llu: failed to get string (form 0x%x)\n",
            die_off(dw, die), die_attr_form(dw, attr));
    }

    *strp = xstrdup(str);
    dwarf_dealloc(dw->dw_dw, str, DW_DLA_STRING);

    return (1);
}

static Dwarf_Off
die_attr_ref(dwarf_t *dw, Dwarf_Die die, Dwarf_Half name)
{
    Dwarf_Attribute attr;
    Dwarf_Off off;

    attr = die_attr(dw, die, name, DW_ATTR_REQ);

    if (dwarf_formref(attr, &off, &dw->dw_err) != DW_DLV_OK) {
        terminate("die %llu: failed to get ref (form 0x%x)\n",
            die_off(dw, die), die_attr_form(dw, attr));
    }

    dwarf_dealloc(dw->dw_dw, attr, DW_DLA_ATTR);

    return (off);
}

static char *
die_name(dwarf_t *dw, Dwarf_Die die)
{
    char *str = NULL;

    (void) die_string(dw, die, DW_AT_name, &str, 0);

    return (str);
}

static int
die_isdecl(dwarf_t *dw, Dwarf_Die die)
{
    Dwarf_Bool val;

    return (die_bool(dw, die, DW_AT_declaration, &val, 0) && val);
}

static int
die_isglobal(dwarf_t *dw, Dwarf_Die die)
{
    Dwarf_Signed vis;
    Dwarf_Bool ext;

    /*
     * Some compilers (gcc) use DW_AT_external to indicate function
     * visibility.  Others (Sun) use DW_AT_visibility.
     */
    if (die_signed(dw, die, DW_AT_visibility, &vis, 0))
        return (vis == DW_VIS_exported);
    else
        return (die_bool(dw, die, DW_AT_external, &ext, 0) && ext);
}

static tdesc_t *
die_add(dwarf_t *dw, Dwarf_Off off)
{
    tdesc_t *tdp = xcalloc(sizeof (tdesc_t));

    tdp->t_id = off;

    tdesc_add(dw, tdp);

    return (tdp);
}

static tdesc_t *
die_lookup_pass1(dwarf_t *dw, Dwarf_Die die, Dwarf_Half name)
{
    Dwarf_Off ref = die_attr_ref(dw, die, name);
    tdesc_t *tdp;

    if ((tdp = tdesc_lookup(dw, ref)) != NULL)
        return (tdp);

    return (die_add(dw, ref));
}

static int
die_mem_offset(dwarf_t *dw, Dwarf_Die die, Dwarf_Half name,
    Dwarf_Unsigned *valp, int req)
{
    Dwarf_Attribute attr;
    Dwarf_Locdesc *loc;
    Dwarf_Signed locnum;

    if ((attr = die_attr(dw, die, name, req)) == NULL)
        return (0); /* die_attr will terminate for us if necessary */

    if (dwarf_loclist(attr, &loc, &locnum, &dw->dw_err) != DW_DLV_OK) {
        terminate("die %llu: failed to get mem offset location list\n",
            die_off(dw, die));
    }

    dwarf_dealloc(dw->dw_dw, attr, DW_DLA_ATTR);

    if (locnum != 1 || loc->ld_s->lr_atom != DW_OP_plus_uconst) {
        terminate("die %llu: cannot parse member offset\n",
            die_off(dw, die));
    }

    *valp = loc->ld_s->lr_number;

    dwarf_dealloc(dw->dw_dw, loc->ld_s, DW_DLA_LOC_BLOCK);
    dwarf_dealloc(dw->dw_dw, loc, DW_DLA_LOCDESC);

    return (1);
}

static tdesc_t *
tdesc_intr_common(dwarf_t *dw, int tid, const char *name, size_t sz)
{
    tdesc_t *tdp;
    intr_t *intr;

    intr = xcalloc(sizeof (intr_t));
    intr->intr_type = INTR_INT;
    intr->intr_signed = 1;
    intr->intr_nbits = sz * NBBY;

    tdp = xcalloc(sizeof (tdesc_t));
    tdp->t_name = xstrdup(name);
    tdp->t_size = sz;
    tdp->t_id = tid;
    tdp->t_type = INTRINSIC;
    tdp->t_intr = intr;
    tdp->t_flags = TDESC_F_RESOLVED;

    tdesc_add(dw, tdp);

    return (tdp);
}

/*
 * Manufacture a void type.  Used for gcc-emitted stabs, where the lack of a
 * type reference implies a reference to a void type.  A void *, for example
 * will be represented by a pointer die without a DW_AT_type.  CTF requires
 * that pointer nodes point to something, so we'll create a void for use as
 * the target.  Note that the DWARF data may already create a void type.  Ours
 * would then be a duplicate, but it'll be removed in the self-uniquification
 * merge performed at the completion of DWARF->tdesc conversion.
 */
static tdesc_t *
tdesc_intr_void(dwarf_t *dw)
{
    if (dw->dw_void == NULL)
        dw->dw_void = tdesc_intr_common(dw, TID_VOID, "void", 0);

    return (dw->dw_void);
}

static tdesc_t *
tdesc_intr_long(dwarf_t *dw)
{
    if (dw->dw_long == NULL) {
        dw->dw_long = tdesc_intr_common(dw, TID_LONG, "long",
            dw->dw_ptrsz);
    }

    return (dw->dw_long);
}

/*
 * Used for creating bitfield types.  We create a copy of an existing intrinsic,
 * adjusting the size of the copy to match what the caller requested.  The
 * caller can then use the copy as the type for a bitfield structure member.
 */
static tdesc_t *
tdesc_intr_clone(dwarf_t *dw, tdesc_t *old, size_t bitsz)
{
    tdesc_t *new = xcalloc(sizeof (tdesc_t));

    if (!(old->t_flags & TDESC_F_RESOLVED)) {
        terminate("tdp %u: attempt to make a bit field from an "
            "unresolved type\n", old->t_id);
    }

    new->t_name = xstrdup(old->t_name);
    new->t_size = old->t_size;
    new->t_id = mfgtid_next(dw);
    new->t_type = INTRINSIC;
    new->t_flags = TDESC_F_RESOLVED;

    new->t_intr = xcalloc(sizeof (intr_t));
    bcopy(old->t_intr, new->t_intr, sizeof (intr_t));
    new->t_intr->intr_nbits = bitsz;

    tdesc_add(dw, new);

    return (new);
}

static void
tdesc_array_create(dwarf_t *dw, Dwarf_Die dim, tdesc_t *arrtdp,
    tdesc_t *dimtdp)
{
    Dwarf_Unsigned uval;
    Dwarf_Signed sval;
    tdesc_t *ctdp;
    Dwarf_Die dim2;
    ardef_t *ar;

    if ((dim2 = die_sibling(dw, dim)) == NULL) {
        ctdp = arrtdp;
    } else if (die_tag(dw, dim2) == DW_TAG_subrange_type) {
        ctdp = xcalloc(sizeof (tdesc_t));
        ctdp->t_id = mfgtid_next(dw);
        debug(3, "die %llu: creating new type %u for sub-dimension\n",
            die_off(dw, dim2), ctdp->t_id);
        tdesc_array_create(dw, dim2, arrtdp, ctdp);
    } else {
        terminate("die %llu: unexpected non-subrange node in array\n",
            die_off(dw, dim2));
    }

    dimtdp->t_type = ARRAY;
    dimtdp->t_ardef = ar = xcalloc(sizeof (ardef_t));

    /*
     * Array bounds can be signed or unsigned, but there are several kinds
     * of signless forms (data1, data2, etc) that take their sign from the
     * routine that is trying to interpret them.  That is, data1 can be
     * either signed or unsigned, depending on whether you use the signed or
     * unsigned accessor function.  GCC will use the signless forms to store
     * unsigned values which have their high bit set, so we need to try to
     * read them first as unsigned to get positive values.  We could also
     * try signed first, falling back to unsigned if we got a negative
     * value.
     */
    if (die_unsigned(dw, dim, DW_AT_upper_bound, &uval, 0))
        ar->ad_nelems = uval + 1;
    else if (die_signed(dw, dim, DW_AT_upper_bound, &sval, 0))
        ar->ad_nelems = sval + 1;
    else
        ar->ad_nelems = 0;

    /*
     * Different compilers use different index types.  Force the type to be
     * a common, known value (long).
     */
    ar->ad_idxtype = tdesc_intr_long(dw);
    ar->ad_contents = ctdp;

    if (ar->ad_contents->t_size != 0) {
        dimtdp->t_size = ar->ad_contents->t_size * ar->ad_nelems;
        dimtdp->t_flags |= TDESC_F_RESOLVED;
    }
}

/*
 * Create a tdesc from an array node.  Some arrays will come with byte size
 * attributes, and thus can be resolved immediately.  Others don't, and will
 * need to wait until the second pass for resolution.
 */
static void
die_array_create(dwarf_t *dw, Dwarf_Die arr, Dwarf_Off off, tdesc_t *tdp)
{
    tdesc_t *arrtdp = die_lookup_pass1(dw, arr, DW_AT_type);
    Dwarf_Unsigned uval;
    Dwarf_Die dim;

    debug(3, "die %llu: creating array\n", off);

    if ((dim = die_child(dw, arr)) == NULL ||
        die_tag(dw, dim) != DW_TAG_subrange_type)
        terminate("die %llu: failed to retrieve array bounds\n", off);

    tdesc_array_create(dw, dim, arrtdp, tdp);

    if (die_unsigned(dw, arr, DW_AT_byte_size, &uval, 0)) {
        tdesc_t *dimtdp;
        int flags;

        tdp->t_size = uval;

        /*
         * Ensure that sub-dimensions have sizes too before marking
         * as resolved.
         */
        flags = TDESC_F_RESOLVED;
        for (dimtdp = tdp->t_ardef->ad_contents;
            dimtdp->t_type == ARRAY;
            dimtdp = dimtdp->t_ardef->ad_contents) {
            if (!(dimtdp->t_flags & TDESC_F_RESOLVED)) {
                flags = 0;
                break;
            }
        }

        tdp->t_flags |= flags;
    }

    debug(3, "die %llu: array nelems %u size %u\n", off,
        tdp->t_ardef->ad_nelems, tdp->t_size);
}

/*ARGSUSED1*/
static int
die_array_resolve(tdesc_t *tdp, tdesc_t **tdpp, void *private)
{
    dwarf_t *dw = private;
    size_t sz;

    if (tdp->t_flags & TDESC_F_RESOLVED)
        return (1);

    debug(3, "trying to resolve array %d (cont %d)\n", tdp->t_id,
        tdp->t_ardef->ad_contents->t_id);

    if ((sz = tdesc_size(tdp->t_ardef->ad_contents)) == 0) {
        debug(3, "unable to resolve array %s (%d) contents %d\n",
            tdesc_name(tdp), tdp->t_id,
            tdp->t_ardef->ad_contents->t_id);

        dw->dw_nunres++;
        return (1);
    }

    tdp->t_size = sz * tdp->t_ardef->ad_nelems;
    tdp->t_flags |= TDESC_F_RESOLVED;

    debug(3, "resolved array %d: %u bytes\n", tdp->t_id, tdp->t_size);

    return (1);
}

/*ARGSUSED1*/
static int
die_array_failed(tdesc_t *tdp, tdesc_t **tdpp, void *private)
{
    tdesc_t *cont = tdp->t_ardef->ad_contents;

    if (tdp->t_flags & TDESC_F_RESOLVED)
        return (1);

    fprintf(stderr, "Array %d: failed to size contents type %s (%d)\n",
        tdp->t_id, tdesc_name(cont), cont->t_id);

    return (1);
}

/*
 * Most enums (those with members) will be resolved during this first pass.
 * Others - those without members (see the file comment) - won't be, and will
 * need to wait until the second pass when they can be matched with their full
 * definitions.
 */
static void
die_enum_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    Dwarf_Die mem;
    Dwarf_Unsigned uval;
    Dwarf_Signed sval;

    debug(3, "die %llu: creating enum\n", off);

    tdp->t_type = ENUM;

    (void) die_unsigned(dw, die, DW_AT_byte_size, &uval, DW_ATTR_REQ);
    tdp->t_size = uval;

    if ((mem = die_child(dw, die)) != NULL) {
        elist_t **elastp = &tdp->t_emem;

        do {
            elist_t *el;

            if (die_tag(dw, mem) != DW_TAG_enumerator) {
                /* Nested type declaration */
                die_create_one(dw, mem);
                continue;
            }

            el = xcalloc(sizeof (elist_t));
            el->el_name = die_name(dw, mem);

            if (die_signed(dw, mem, DW_AT_const_value, &sval, 0)) {
                el->el_number = sval;
            } else if (die_unsigned(dw, mem, DW_AT_const_value,
                &uval, 0)) {
                el->el_number = uval;
            } else {
                terminate("die %llu: enum %llu: member without "
                    "value\n", off, die_off(dw, mem));
            }

            debug(3, "die %llu: enum %llu: created %s = %d\n", off,
                die_off(dw, mem), el->el_name, el->el_number);

            *elastp = el;
            elastp = &el->el_next;

        } while ((mem = die_sibling(dw, mem)) != NULL);

        hash_add(dw->dw_enumhash, tdp);

        tdp->t_flags |= TDESC_F_RESOLVED;

        if (tdp->t_name != NULL) {
            iidesc_t *ii = xcalloc(sizeof (iidesc_t));
            ii->ii_type = II_SOU;
            ii->ii_name = xstrdup(tdp->t_name);
            ii->ii_dtype = tdp;

            iidesc_add(dw->dw_td->td_iihash, ii);
        }
    }
}

static int
die_enum_match(void *arg1, void *arg2)
{
    tdesc_t *tdp = arg1, **fullp = arg2;

    if (tdp->t_emem != NULL) {
        *fullp = tdp;
        return (-1); /* stop the iteration */
    }

    return (0);
}

/*ARGSUSED1*/
static int
die_enum_resolve(tdesc_t *tdp, tdesc_t **tdpp, void *private)
{
    dwarf_t *dw = private;
    tdesc_t *full = NULL;

    if (tdp->t_flags & TDESC_F_RESOLVED)
        return (1);

    (void) hash_find_iter(dw->dw_enumhash, tdp, die_enum_match, &full);

    /*
     * The answer to this one won't change from iteration to iteration,
     * so don't even try.
     */
    if (full == NULL) {
        terminate("tdp %u: enum %s has no members\n", tdp->t_id,
            tdesc_name(tdp));
    }

    debug(3, "tdp %u: enum %s redirected to %u\n", tdp->t_id,
        tdesc_name(tdp), full->t_id);

    tdp->t_flags |= TDESC_F_RESOLVED;

    return (1);
}

static int
die_fwd_map(void *arg1, void *arg2)
{
    tdesc_t *fwd = arg1, *sou = arg2;

    debug(3, "tdp %u: mapped forward %s to sou %u\n", fwd->t_id,
        tdesc_name(fwd), sou->t_id);
    fwd->t_tdesc = sou;

    return (0);
}

/*
 * Structures and unions will never be resolved during the first pass, as we
 * won't be able to fully determine the member sizes.  The second pass, which
 * have access to sizing information, will be able to complete the resolution.
 */
static void
die_sou_create(dwarf_t *dw, Dwarf_Die str, Dwarf_Off off, tdesc_t *tdp,
    int type, const char *typename)
{
    Dwarf_Unsigned sz, bitsz, bitoff;
    Dwarf_Die mem;
    mlist_t *ml, **mlastp;
    iidesc_t *ii;

    tdp->t_type = (die_isdecl(dw, str) ? FORWARD : type);

    debug(3, "die %llu: creating %s %s\n", off,
        (tdp->t_type == FORWARD ? "forward decl" : typename),
        tdesc_name(tdp));

    if (tdp->t_type == FORWARD) {
        hash_add(dw->dw_fwdhash, tdp);
        return;
    }

    (void) hash_find_iter(dw->dw_fwdhash, tdp, die_fwd_map, tdp);

    (void) die_unsigned(dw, str, DW_AT_byte_size, &sz, DW_ATTR_REQ);
    tdp->t_size = sz;

    /*
     * GCC allows empty SOUs as an extension.
     */
    if ((mem = die_child(dw, str)) == NULL)
        goto out;

    mlastp = &tdp->t_members;

    do {
        Dwarf_Off memoff = die_off(dw, mem);
        Dwarf_Half tag = die_tag(dw, mem);
        Dwarf_Unsigned mloff;

        if (tag != DW_TAG_member) {
            /* Nested type declaration */
            die_create_one(dw, mem);
            continue;
        }

        debug(3, "die %llu: mem %llu: creating member\n", off, memoff);

        ml = xcalloc(sizeof (mlist_t));

        /*
         * This could be a GCC anon struct/union member, so we'll allow
         * an empty name, even though nothing can really handle them
         * properly.  Note that some versions of GCC miss out debug
         * info for anon structs, though recent versions are fixed (gcc
         * bug 11816).
         */
        if ((ml->ml_name = die_name(dw, mem)) == NULL)
            ml->ml_name = "";

        ml->ml_type = die_lookup_pass1(dw, mem, DW_AT_type);

        if (die_mem_offset(dw, mem, DW_AT_data_member_location,
            &mloff, 0)) {
            debug(3, "die %llu: got mloff %llx\n", off,
                (u_longlong_t)mloff);
            ml->ml_offset = mloff * 8;
        }

        if (die_unsigned(dw, mem, DW_AT_bit_size, &bitsz, 0))
            ml->ml_size = bitsz;
        else
            ml->ml_size = tdesc_bitsize(ml->ml_type);

        if (die_unsigned(dw, mem, DW_AT_bit_offset, &bitoff, 0)) {
#ifdef  _BIG_ENDIAN
            ml->ml_offset += bitoff;
#else
            ml->ml_offset += tdesc_bitsize(ml->ml_type) - bitoff -
                ml->ml_size;
#endif
        }

        debug(3, "die %llu: mem %llu: created \"%s\" (off %u sz %u)\n",
            off, memoff, ml->ml_name, ml->ml_offset, ml->ml_size);

        *mlastp = ml;
        mlastp = &ml->ml_next;
    } while ((mem = die_sibling(dw, mem)) != NULL);

    /*
     * GCC will attempt to eliminate unused types, thus decreasing the
     * size of the emitted dwarf.  That is, if you declare a foo_t in your
     * header, include said header in your source file, and neglect to
     * actually use (directly or indirectly) the foo_t in the source file,
     * the foo_t won't make it into the emitted DWARF.  So, at least, goes
     * the theory.
     *
     * Occasionally, it'll emit the DW_TAG_structure_type for the foo_t,
     * and then neglect to emit the members.  Strangely, the loner struct
     * tag will always be followed by a proper nested declaration of
     * something else.  This is clearly a bug, but we're not going to have
     * time to get it fixed before this goo goes back, so we'll have to work
     * around it.  If we see a no-membered struct with a nested declaration
     * (i.e. die_child of the struct tag won't be null), we'll ignore it.
     * Being paranoid, we won't simply remove it from the hash.  Instead,
     * we'll decline to create an iidesc for it, thus ensuring that this
     * type won't make it into the output file.  To be safe, we'll also
     * change the name.
     */
    if (tdp->t_members == NULL) {
        const char *old = tdesc_name(tdp);
        size_t newsz = 7 + strlen(old) + 1;
        char *new = xmalloc(newsz);
        (void) snprintf(new, newsz, "orphan %s", old);

        debug(3, "die %llu: worked around %s %s\n", off, typename, old);

        if (tdp->t_name != NULL)
            free(tdp->t_name);
        tdp->t_name = new;
        return;
    }

out:
    if (tdp->t_name != NULL) {
        ii = xcalloc(sizeof (iidesc_t));
        ii->ii_type = II_SOU;
        ii->ii_name = xstrdup(tdp->t_name);
        ii->ii_dtype = tdp;

        iidesc_add(dw->dw_td->td_iihash, ii);
    }
}

static void
die_struct_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    die_sou_create(dw, die, off, tdp, STRUCT, "struct");
}

static void
die_union_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    die_sou_create(dw, die, off, tdp, UNION, "union");
}

/*ARGSUSED1*/
static int
die_sou_resolve(tdesc_t *tdp, tdesc_t **tdpp, void *private)
{
    dwarf_t *dw = private;
    mlist_t *ml;
    tdesc_t *mt;

    if (tdp->t_flags & TDESC_F_RESOLVED)
        return (1);

    debug(3, "resolving sou %s\n", tdesc_name(tdp));

    for (ml = tdp->t_members; ml != NULL; ml = ml->ml_next) {
        if (ml->ml_size == 0) {
            mt = tdesc_basetype(ml->ml_type);

            if ((ml->ml_size = tdesc_bitsize(mt)) != 0)
                continue;

            /*
             * For empty members, or GCC/C99 flexible array
             * members, a size of 0 is correct.
             */
            if (mt->t_members == NULL)
                continue;
            if (mt->t_type == ARRAY && mt->t_ardef->ad_nelems == 0)
                continue;

            dw->dw_nunres++;
            return (1);
        }

        if ((mt = tdesc_basetype(ml->ml_type)) == NULL) {
            dw->dw_nunres++;
            return (1);
        }

        if (ml->ml_size != 0 && mt->t_type == INTRINSIC &&
            mt->t_intr->intr_nbits != ml->ml_size) {
            /*
             * This member is a bitfield, and needs to reference
             * an intrinsic type with the same width.  If the
             * currently-referenced type isn't of the same width,
             * we'll copy it, adjusting the width of the copy to
             * the size we'd like.
             */
            debug(3, "tdp %u: creating bitfield for %d bits\n",
                tdp->t_id, ml->ml_size);

            ml->ml_type = tdesc_intr_clone(dw, mt, ml->ml_size);
        }
    }

    tdp->t_flags |= TDESC_F_RESOLVED;

    return (1);
}

/*ARGSUSED1*/
static int
die_sou_failed(tdesc_t *tdp, tdesc_t **tdpp, void *private)
{
    const char *typename = (tdp->t_type == STRUCT ? "struct" : "union");
    mlist_t *ml;

    if (tdp->t_flags & TDESC_F_RESOLVED)
        return (1);

    for (ml = tdp->t_members; ml != NULL; ml = ml->ml_next) {
        if (ml->ml_size == 0) {
            fprintf(stderr, "%s %d: failed to size member \"%s\" "
                "of type %s (%d)\n", typename, tdp->t_id,
                ml->ml_name, tdesc_name(ml->ml_type),
                ml->ml_type->t_id);
        }
    }

    return (1);
}

static void
die_funcptr_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    Dwarf_Attribute attr;
    Dwarf_Half tag;
    Dwarf_Die arg;
    fndef_t *fn;
    int i;

    debug(3, "die %llu: creating function pointer\n", off);

    /*
     * We'll begin by processing any type definition nodes that may be
     * lurking underneath this one.
     */
    for (arg = die_child(dw, die); arg != NULL;
        arg = die_sibling(dw, arg)) {
        if ((tag = die_tag(dw, arg)) != DW_TAG_formal_parameter &&
            tag != DW_TAG_unspecified_parameters) {
            /* Nested type declaration */
            die_create_one(dw, arg);
        }
    }

    if (die_isdecl(dw, die)) {
        /*
         * This is a prototype.  We don't add prototypes to the
         * tree, so we're going to drop the tdesc.  Unfortunately,
         * it has already been added to the tree.  Nobody will reference
         * it, though, and it will be leaked.
         */
        return;
    }

    fn = xcalloc(sizeof (fndef_t));

    tdp->t_type = FUNCTION;

    if ((attr = die_attr(dw, die, DW_AT_type, 0)) != NULL) {
        dwarf_dealloc(dw->dw_dw, attr, DW_DLA_ATTR);
        fn->fn_ret = die_lookup_pass1(dw, die, DW_AT_type);
    } else {
        fn->fn_ret = tdesc_intr_void(dw);
    }

    /*
     * Count the arguments to the function, then read them in.
     */
    for (fn->fn_nargs = 0, arg = die_child(dw, die); arg != NULL;
        arg = die_sibling(dw, arg)) {
        if ((tag = die_tag(dw, arg)) == DW_TAG_formal_parameter)
            fn->fn_nargs++;
        else if (tag == DW_TAG_unspecified_parameters &&
            fn->fn_nargs > 0)
            fn->fn_vargs = 1;
    }

    if (fn->fn_nargs != 0) {
        debug(3, "die %llu: adding %d argument%s\n", off, fn->fn_nargs,
            (fn->fn_nargs > 1 ? "s" : ""));

        fn->fn_args = xcalloc(sizeof (tdesc_t *) * fn->fn_nargs);
        for (i = 0, arg = die_child(dw, die);
            arg != NULL && i < fn->fn_nargs;
            arg = die_sibling(dw, arg)) {
            if (die_tag(dw, arg) != DW_TAG_formal_parameter)
                continue;

            fn->fn_args[i++] = die_lookup_pass1(dw, arg,
                DW_AT_type);
        }
    }

    tdp->t_fndef = fn;
    tdp->t_flags |= TDESC_F_RESOLVED;
}

/*
 * GCC and DevPro use different names for the base types.  While the terms are
 * the same, they are arranged in a different order.  Some terms, such as int,
 * are implied in one, and explicitly named in the other.  Given a base type
 * as input, this routine will return a common name, along with an intr_t
 * that reflects said name.
 */
static intr_t *
die_base_name_parse(const char *name, char **newp)
{
    char buf[100];
    char *base, *c;
    int nlong = 0, nshort = 0, nchar = 0, nint = 0;
    int sign = 1;
    char fmt = '\0';
    intr_t *intr;

    if (strlen(name) > sizeof (buf) - 1)
        terminate("base type name \"%s\" is too long\n", name);

    strncpy(buf, name, sizeof (buf));

    for (c = strtok(buf, " "); c != NULL; c = strtok(NULL, " ")) {
        if (strcmp(c, "signed") == 0)
            sign = 1;
        else if (strcmp(c, "unsigned") == 0)
            sign = 0;
        else if (strcmp(c, "long") == 0)
            nlong++;
        else if (strcmp(c, "char") == 0) {
            nchar++;
            fmt = 'c';
        } else if (strcmp(c, "short") == 0)
            nshort++;
        else if (strcmp(c, "int") == 0)
            nint++;
        else {
            /*
             * If we don't recognize any of the tokens, we'll tell
             * the caller to fall back to the dwarf-provided
             * encoding information.
             */
            return (NULL);
        }
    }

    if (nchar > 1 || nshort > 1 || nint > 1 || nlong > 2)
        return (NULL);

    if (nchar > 0) {
        if (nlong > 0 || nshort > 0 || nint > 0)
            return (NULL);

        base = "char";

    } else if (nshort > 0) {
        if (nlong > 0)
            return (NULL);

        base = "short";

    } else if (nlong > 0) {
        base = "long";

    } else {
        base = "int";
    }

    intr = xcalloc(sizeof (intr_t));
    intr->intr_type = INTR_INT;
    intr->intr_signed = sign;
    intr->intr_iformat = fmt;

    snprintf(buf, sizeof (buf), "%s%s%s",
        (sign ? "" : "unsigned "),
        (nlong > 1 ? "long " : ""),
        base);

    *newp = xstrdup(buf);
    return (intr);
}

typedef struct fp_size_map {
    size_t fsm_typesz[2];   /* size of {32,64} type */
    uint_t fsm_enc[3];  /* CTF_FP_* for {bare,cplx,imagry} type */
} fp_size_map_t;

static const fp_size_map_t fp_encodings[] = {
    { { 4, 4 }, { CTF_FP_SINGLE, CTF_FP_CPLX, CTF_FP_IMAGRY } },
    { { 8, 8 }, { CTF_FP_DOUBLE, CTF_FP_DCPLX, CTF_FP_DIMAGRY } },
#ifdef __sparc
    { { 16, 16 }, { CTF_FP_LDOUBLE, CTF_FP_LDCPLX, CTF_FP_LDIMAGRY } },
#else
    { { 12, 16 }, { CTF_FP_LDOUBLE, CTF_FP_LDCPLX, CTF_FP_LDIMAGRY } },
#endif
    { { 0, 0 } }
};

static uint_t
die_base_type2enc(dwarf_t *dw, Dwarf_Off off, Dwarf_Signed enc, size_t sz)
{
    const fp_size_map_t *map = fp_encodings;
    uint_t szidx = dw->dw_ptrsz == sizeof (uint64_t);
    uint_t mult = 1, col = 0;

    if (enc == DW_ATE_complex_float) {
        mult = 2;
        col = 1;
    } else if (enc == DW_ATE_imaginary_float ||
        enc == DW_ATE_SUN_imaginary_float)
        col = 2;

    while (map->fsm_typesz[szidx] != 0) {
        if (map->fsm_typesz[szidx] * mult == sz)
            return (map->fsm_enc[col]);
        map++;
    }

    terminate("die %llu: unrecognized real type size %u\n", off, sz);
    /*NOTREACHED*/
    return (0);
}

static intr_t *
die_base_from_dwarf(dwarf_t *dw, Dwarf_Die base, Dwarf_Off off, size_t sz)
{
    intr_t *intr = xcalloc(sizeof (intr_t));
    Dwarf_Signed enc;

    (void) die_signed(dw, base, DW_AT_encoding, &enc, DW_ATTR_REQ);

    switch (enc) {
    case DW_ATE_unsigned:
    case DW_ATE_address:
        intr->intr_type = INTR_INT;
        break;
    case DW_ATE_unsigned_char:
        intr->intr_type = INTR_INT;
        intr->intr_iformat = 'c';
        break;
    case DW_ATE_signed:
        intr->intr_type = INTR_INT;
        intr->intr_signed = 1;
        break;
    case DW_ATE_signed_char:
        intr->intr_type = INTR_INT;
        intr->intr_signed = 1;
        intr->intr_iformat = 'c';
        break;
    case DW_ATE_boolean:
        intr->intr_type = INTR_INT;
        intr->intr_signed = 1;
        intr->intr_iformat = 'b';
        break;
    case DW_ATE_float:
    case DW_ATE_complex_float:
    case DW_ATE_imaginary_float:
    case DW_ATE_SUN_imaginary_float:
    case DW_ATE_SUN_interval_float:
        intr->intr_type = INTR_REAL;
        intr->intr_signed = 1;
        intr->intr_fformat = die_base_type2enc(dw, off, enc, sz);
        break;
    default:
        terminate("die %llu: unknown base type encoding 0x%llx\n",
            off, enc);
    }

    return (intr);
}

static void
die_base_create(dwarf_t *dw, Dwarf_Die base, Dwarf_Off off, tdesc_t *tdp)
{
    Dwarf_Unsigned sz;
    intr_t *intr;
    char *new;

    debug(3, "die %llu: creating base type\n", off);

    /*
     * The compilers have their own clever (internally inconsistent) ideas
     * as to what base types should look like.  Some times gcc will, for
     * example, use DW_ATE_signed_char for char.  Other times, however, it
     * will use DW_ATE_signed.  Needless to say, this causes some problems
     * down the road, particularly with merging.  We do, however, use the
     * DWARF idea of type sizes, as this allows us to avoid caring about
     * the data model.
     */
    (void) die_unsigned(dw, base, DW_AT_byte_size, &sz, DW_ATTR_REQ);

    if (tdp->t_name == NULL)
        terminate("die %llu: base type without name\n", off);

    /* XXX make a name parser for float too */
    if ((intr = die_base_name_parse(tdp->t_name, &new)) != NULL) {
        /* Found it.  We'll use the parsed version */
        debug(3, "die %llu: name \"%s\" remapped to \"%s\"\n", off,
            tdesc_name(tdp), new);

        free(tdp->t_name);
        tdp->t_name = new;
    } else {
        /*
         * We didn't recognize the type, so we'll create an intr_t
         * based on the DWARF data.
         */
        debug(3, "die %llu: using dwarf data for base \"%s\"\n", off,
            tdesc_name(tdp));

        intr = die_base_from_dwarf(dw, base, off, sz);
    }

    intr->intr_nbits = sz * 8;

    tdp->t_type = INTRINSIC;
    tdp->t_intr = intr;
    tdp->t_size = sz;

    tdp->t_flags |= TDESC_F_RESOLVED;
}

static void
die_through_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp,
    int type, const char *typename)
{
    Dwarf_Attribute attr;

    debug(3, "die %llu: creating %s\n", off, typename);

    tdp->t_type = type;

    if ((attr = die_attr(dw, die, DW_AT_type, 0)) != NULL) {
        dwarf_dealloc(dw->dw_dw, attr, DW_DLA_ATTR);
        tdp->t_tdesc = die_lookup_pass1(dw, die, DW_AT_type);
    } else {
        tdp->t_tdesc = tdesc_intr_void(dw);
    }

    if (type == POINTER)
        tdp->t_size = dw->dw_ptrsz;

    tdp->t_flags |= TDESC_F_RESOLVED;

    if (type == TYPEDEF) {
        iidesc_t *ii = xcalloc(sizeof (iidesc_t));
        ii->ii_type = II_TYPE;
        ii->ii_name = xstrdup(tdp->t_name);
        ii->ii_dtype = tdp;

        iidesc_add(dw->dw_td->td_iihash, ii);
    }
}

static void
die_typedef_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    die_through_create(dw, die, off, tdp, TYPEDEF, "typedef");
}

static void
die_const_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    die_through_create(dw, die, off, tdp, CONST, "const");
}

static void
die_pointer_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    die_through_create(dw, die, off, tdp, POINTER, "pointer");
}

static void
die_restrict_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    die_through_create(dw, die, off, tdp, RESTRICT, "restrict");
}

static void
die_volatile_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    die_through_create(dw, die, off, tdp, VOLATILE, "volatile");
}

/*ARGSUSED3*/
static void
die_function_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    Dwarf_Die arg;
    Dwarf_Half tag;
    iidesc_t *ii;
    char *name;

    debug(3, "die %llu: creating function definition\n", off);

    /*
     * We'll begin by processing any type definition nodes that may be
     * lurking underneath this one.
     */
    for (arg = die_child(dw, die); arg != NULL;
        arg = die_sibling(dw, arg)) {
        if ((tag = die_tag(dw, arg)) != DW_TAG_formal_parameter &&
            tag != DW_TAG_variable) {
            /* Nested type declaration */
            die_create_one(dw, arg);
        }
    }

    if (die_isdecl(dw, die) || (name = die_name(dw, die)) == NULL) {
        /*
         * We process neither prototypes nor subprograms without
         * names.
         */
        return;
    }

    ii = xcalloc(sizeof (iidesc_t));
    ii->ii_type = die_isglobal(dw, die) ? II_GFUN : II_SFUN;
    ii->ii_name = name;
    if (ii->ii_type == II_SFUN)
        ii->ii_owner = xstrdup(dw->dw_cuname);

    debug(3, "die %llu: function %s is %s\n", off, ii->ii_name,
        (ii->ii_type == II_GFUN ? "global" : "static"));

    if (die_attr(dw, die, DW_AT_type, 0) != NULL)
        ii->ii_dtype = die_lookup_pass1(dw, die, DW_AT_type);
    else
        ii->ii_dtype = tdesc_intr_void(dw);

    for (arg = die_child(dw, die); arg != NULL;
        arg = die_sibling(dw, arg)) {
        char *name;

        debug(3, "die %llu: looking at sub member at %llu\n",
            off, die_off(dw, die));

        if (die_tag(dw, arg) != DW_TAG_formal_parameter)
            continue;

        if ((name = die_name(dw, arg)) == NULL) {
            terminate("die %llu: func arg %d has no name\n",
                off, ii->ii_nargs + 1);
        }

        if (strcmp(name, "...") == 0) {
            free(name);
            ii->ii_vargs = 1;
            continue;
        }

        ii->ii_nargs++;
    }

    if (ii->ii_nargs > 0) {
        int i;

        debug(3, "die %llu: function has %d argument%s\n", off,
            ii->ii_nargs, (ii->ii_nargs == 1 ? "" : "s"));

        ii->ii_args = xcalloc(sizeof (tdesc_t) * ii->ii_nargs);

        for (arg = die_child(dw, die), i = 0;
            arg != NULL && i < ii->ii_nargs;
            arg = die_sibling(dw, arg)) {
            if (die_tag(dw, arg) != DW_TAG_formal_parameter)
                continue;

            ii->ii_args[i++] = die_lookup_pass1(dw, arg,
                DW_AT_type);
        }
    }

    iidesc_add(dw->dw_td->td_iihash, ii);
}

/*ARGSUSED3*/
static void
die_variable_create(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    iidesc_t *ii;
    char *name;

    debug(3, "die %llu: creating object definition\n", off);

    if (die_isdecl(dw, die) || (name = die_name(dw, die)) == NULL)
        return; /* skip prototypes and nameless objects */

    ii = xcalloc(sizeof (iidesc_t));
    ii->ii_type = die_isglobal(dw, die) ? II_GVAR : II_SVAR;
    ii->ii_name = name;
    ii->ii_dtype = die_lookup_pass1(dw, die, DW_AT_type);
    if (ii->ii_type == II_SVAR)
        ii->ii_owner = xstrdup(dw->dw_cuname);

    iidesc_add(dw->dw_td->td_iihash, ii);
}

/*ARGSUSED2*/
static int
die_fwd_resolve(tdesc_t *fwd, tdesc_t **fwdp, void *private)
{
    if (fwd->t_flags & TDESC_F_RESOLVED)
        return (1);

    if (fwd->t_tdesc != NULL) {
        debug(3, "tdp %u: unforwarded %s\n", fwd->t_id,
            tdesc_name(fwd));
        *fwdp = fwd->t_tdesc;
    }

    fwd->t_flags |= TDESC_F_RESOLVED;

    return (1);
}

/*ARGSUSED*/
static void
die_lexblk_descend(dwarf_t *dw, Dwarf_Die die, Dwarf_Off off, tdesc_t *tdp)
{
    Dwarf_Die child = die_child(dw, die);

    if (child != NULL)
        die_create(dw, child);
}

/*
 * Used to map the die to a routine which can parse it, using the tag to do the
 * mapping.  While the processing of most tags entails the creation of a tdesc,
 * there are a few which don't - primarily those which result in the creation of
 * iidescs which refer to existing tdescs.
 */

#define DW_F_NOTDP  0x1 /* Don't create a tdesc for the creator */

typedef struct die_creator {
    Dwarf_Half dc_tag;
    uint16_t dc_flags;
    void (*dc_create)(dwarf_t *, Dwarf_Die, Dwarf_Off, tdesc_t *);
} die_creator_t;

static const die_creator_t die_creators[] = {
    { DW_TAG_array_type,        0,      die_array_create },
    { DW_TAG_enumeration_type,  0,      die_enum_create },
    { DW_TAG_lexical_block,     DW_F_NOTDP, die_lexblk_descend },
    { DW_TAG_pointer_type,      0,      die_pointer_create },
    { DW_TAG_structure_type,    0,      die_struct_create },
    { DW_TAG_subroutine_type,   0,      die_funcptr_create },
    { DW_TAG_typedef,       0,      die_typedef_create },
    { DW_TAG_union_type,        0,      die_union_create },
    { DW_TAG_base_type,     0,      die_base_create },
    { DW_TAG_const_type,        0,      die_const_create },
    { DW_TAG_subprogram,        DW_F_NOTDP, die_function_create },
    { DW_TAG_variable,      DW_F_NOTDP, die_variable_create },
    { DW_TAG_volatile_type,     0,      die_volatile_create },
    { DW_TAG_restrict_type,     0,      die_restrict_create },
    { 0, 0, NULL }
};

static const die_creator_t *
die_tag2ctor(Dwarf_Half tag)
{
    const die_creator_t *dc;

    for (dc = die_creators; dc->dc_create != NULL; dc++) {
        if (dc->dc_tag == tag)
            return (dc);
    }

    return (NULL);
}

static void
die_create_one(dwarf_t *dw, Dwarf_Die die)
{
    Dwarf_Off off = die_off(dw, die);
    const die_creator_t *dc;
    Dwarf_Half tag;
    tdesc_t *tdp;

    debug(3, "die %llu: create_one\n", off);

    if (off > dw->dw_maxoff) {
        terminate("illegal die offset %llu (max %llu)\n", off,
            dw->dw_maxoff);
    }

    tag = die_tag(dw, die);

    if ((dc = die_tag2ctor(tag)) == NULL) {
        debug(2, "die %llu: ignoring tag type %x\n", off, tag);
        return;
    }

    if ((tdp = tdesc_lookup(dw, off)) == NULL &&
        !(dc->dc_flags & DW_F_NOTDP)) {
        tdp = xcalloc(sizeof (tdesc_t));
        tdp->t_id = off;
        tdesc_add(dw, tdp);
    }

    if (tdp != NULL)
        tdp->t_name = die_name(dw, die);

    dc->dc_create(dw, die, off, tdp);
}

static void
die_create(dwarf_t *dw, Dwarf_Die die)
{
    do {
        die_create_one(dw, die);
    } while ((die = die_sibling(dw, die)) != NULL);
}

static tdtrav_cb_f die_resolvers[] = {
    NULL,
    NULL,           /* intrinsic */
    NULL,           /* pointer */
    die_array_resolve,  /* array */
    NULL,           /* function */
    die_sou_resolve,    /* struct */
    die_sou_resolve,    /* union */
    die_enum_resolve,   /* enum */
    die_fwd_resolve,    /* forward */
    NULL,           /* typedef */
    NULL,           /* typedef unres */
    NULL,           /* volatile */
    NULL,           /* const */
    NULL,           /* restrict */
};

static tdtrav_cb_f die_fail_reporters[] = {
    NULL,
    NULL,           /* intrinsic */
    NULL,           /* pointer */
    die_array_failed,   /* array */
    NULL,           /* function */
    die_sou_failed,     /* struct */
    die_sou_failed,     /* union */
    NULL,           /* enum */
    NULL,           /* forward */
    NULL,           /* typedef */
    NULL,           /* typedef unres */
    NULL,           /* volatile */
    NULL,           /* const */
    NULL,           /* restrict */
};

static void
die_resolve(dwarf_t *dw)
{
    int last = -1;
    int pass = 0;

    do {
        pass++;
        dw->dw_nunres = 0;

        (void) iitraverse_hash(dw->dw_td->td_iihash,
            &dw->dw_td->td_curvgen, NULL, NULL, die_resolvers, dw);

        debug(3, "resolve: pass %d, %u left\n", pass, dw->dw_nunres);

        if (dw->dw_nunres == last) {
            fprintf(stderr, "%s: failed to resolve the following "
                "types:\n", progname);

            (void) iitraverse_hash(dw->dw_td->td_iihash,
                &dw->dw_td->td_curvgen, NULL, NULL,
                die_fail_reporters, dw);

            terminate("failed to resolve types\n");
        }

        last = dw->dw_nunres;

    } while (dw->dw_nunres != 0);
}

/*
 * Any object containing a function or object symbol at any scope should also
 * contain DWARF data.
 */
static boolean_t
should_have_dwarf(Elf *elf)
{
    Elf_Scn *scn = NULL;
    Elf_Data *data = NULL;
    GElf_Shdr shdr;
    GElf_Sym sym;
    uint32_t symdx = 0;
    size_t nsyms = 0;
    boolean_t found = B_FALSE;

    while ((scn = elf_nextscn(elf, scn)) != NULL) {
        gelf_getshdr(scn, &shdr);

        if (shdr.sh_type == SHT_SYMTAB) {
            found = B_TRUE;
            break;
        }
    }

    if (!found)
        terminate("cannot convert stripped objects\n");

    data = elf_getdata(scn, NULL);
    nsyms = shdr.sh_size / shdr.sh_entsize;

    for (symdx = 0; symdx < nsyms; symdx++) {
        gelf_getsym(data, symdx, &sym);

        if ((GELF_ST_TYPE(sym.st_info) == STT_FUNC) ||
            (GELF_ST_TYPE(sym.st_info) == STT_TLS) ||
            (GELF_ST_TYPE(sym.st_info) == STT_OBJECT)) {
            char *name;

            name = elf_strptr(elf, shdr.sh_link, sym.st_name);

            /* Studio emits these local symbols regardless */
            if ((strcmp(name, "Bbss.bss") != 0) &&
                (strcmp(name, "Ttbss.bss") != 0) &&
                (strcmp(name, "Ddata.data") != 0) &&
                (strcmp(name, "Ttdata.data") != 0) &&
                (strcmp(name, "Drodata.rodata") != 0))
                return (B_TRUE);
        }
    }

    return (B_FALSE);
}

/*ARGSUSED*/
int
dw_read(tdata_t *td, Elf *elf, const char *filename)
{
    Dwarf_Unsigned abboff, hdrlen, nxthdr;
    Dwarf_Half vers, addrsz;
    Dwarf_Die cu, child;
    dwarf_t dw;
    char *prod = NULL;
    int rc;

    bzero(&dw, sizeof (dwarf_t));
    dw.dw_td = td;
    dw.dw_ptrsz = elf_ptrsz(elf);
    dw.dw_mfgtid_last = TID_MFGTID_BASE;
    dw.dw_tidhash = hash_new(TDESC_HASH_BUCKETS, tdesc_idhash, tdesc_idcmp);
    dw.dw_fwdhash = hash_new(TDESC_HASH_BUCKETS, tdesc_namehash,
        tdesc_namecmp);
    dw.dw_enumhash = hash_new(TDESC_HASH_BUCKETS, tdesc_namehash,
        tdesc_namecmp);

    if ((rc = dwarf_elf_init(elf, DW_DLC_READ, NULL, NULL, &dw.dw_dw,
        &dw.dw_err)) == DW_DLV_NO_ENTRY) {
        if (should_have_dwarf(elf)) {
            errno = ENOENT;
            return (-1);
        } else {
            return (0);
        }
    } else if (rc != DW_DLV_OK) {
        if (dwarf_errno(dw.dw_err) == DW_DLE_DEBUG_INFO_NULL) {
            /*
             * There's no type data in the DWARF section, but
             * libdwarf is too clever to handle that properly.
             */
            return (0);
        }

        terminate("failed to initialize DWARF: %s\n",
            dwarf_errmsg(dw.dw_err));
    }

    if ((rc = dwarf_next_cu_header(dw.dw_dw, &hdrlen, &vers, &abboff,
        &addrsz, &nxthdr, &dw.dw_err)) != DW_DLV_OK)
        terminate("file does not contain valid DWARF data: %s\n",
            dwarf_errmsg(dw.dw_err));

    /*
     * Some compilers emit no DWARF for empty files, others emit an empty
     * compilation unit.
     */
    if ((cu = die_sibling(&dw, NULL)) == NULL ||
        ((child = die_child(&dw, cu)) == NULL) &&
        should_have_dwarf(elf)) {
        terminate("file does not contain dwarf type data "
            "(try compiling with -g)\n");
    } else if (child == NULL) {
        return (0);
    }

    dw.dw_maxoff = nxthdr - 1;

    if (dw.dw_maxoff > TID_FILEMAX)
        terminate("file contains too many types\n");

    debug(1, "DWARF version: %d\n", vers);
    if (vers != DWARF_VERSION) {
        terminate("file contains incompatible version %d DWARF code "
            "(version 2 required)\n", vers);
    }

    if (die_string(&dw, cu, DW_AT_producer, &prod, 0)) {
        debug(1, "DWARF emitter: %s\n", prod);
        free(prod);
    }

    if ((dw.dw_cuname = die_name(&dw, cu)) != NULL) {
        char *base = xstrdup(basename(dw.dw_cuname));
        free(dw.dw_cuname);
        dw.dw_cuname = base;

        debug(1, "CU name: %s\n", dw.dw_cuname);
    }

    die_create(&dw, child);

    if ((rc = dwarf_next_cu_header(dw.dw_dw, &hdrlen, &vers, &abboff,
        &addrsz, &nxthdr, &dw.dw_err)) != DW_DLV_NO_ENTRY)
        terminate("multiple compilation units not supported\n");

    (void) dwarf_finish(dw.dw_dw, &dw.dw_err);

    die_resolve(&dw);

    cvt_fixups(td, dw.dw_ptrsz);

    /* leak the dwarf_t */

    return (0);
}