gdb/dwarf2expr.c - gdb

Global variables defined

Data types defined

Functions defined

Source code

  1. /* DWARF 2 Expression Evaluator.

  3.    Copyright (C) 2001-2015 Free Software Foundation, Inc.

  5.    Contributed by Daniel Berlin (dan@dberlin.org)

  7.    This file is part of GDB.

  9.    This program is free software; you can redistribute it and/or modify
  10.    it under the terms of the GNU General Public License as published by
  11.    the Free Software Foundation; either version 3 of the License, or
  12.    (at your option) any later version.

  14.    This program is distributed in the hope that it will be useful,
  15.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17.    GNU General Public License for more details.

  19.    You should have received a copy of the GNU General Public License
  20.    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

  22. #include "defs.h"
  23. #include "symtab.h"
  24. #include "gdbtypes.h"
  25. #include "value.h"
  26. #include "gdbcore.h"
  27. #include "dwarf2.h"
  28. #include "dwarf2expr.h"

  30. /* Local prototypes.  */

  32. static void execute_stack_op (struct dwarf_expr_context *,
  33.                               const gdb_byte *, const gdb_byte *);

  35. /* Cookie for gdbarch data.  */

  37. ‌static struct gdbarch_data *dwarf_arch_cookie;

  39. /* This holds gdbarch-specific types used by the DWARF expression
  40.    evaluator.  See comments in execute_stack_op.  */

  42. ‌struct dwarf_gdbarch_types
  43. {
  44.   struct type *dw_types[3];
  45. };

  47. /* Allocate and fill in dwarf_gdbarch_types for an arch.  */

  49. static void *
  50. ‌dwarf_gdbarch_types_init (struct gdbarch *gdbarch)
  51. {
  52.   struct dwarf_gdbarch_types *types
  53.     = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct dwarf_gdbarch_types);

  55.   /* The types themselves are lazily initialized.  */

  57.   return types;
  58. }

  60. /* Return the type used for DWARF operations where the type is
  61.    unspecified in the DWARF spec.  Only certain sizes are
  62.    supported.  */

  64. static struct type *
  65. ‌dwarf_expr_address_type (struct dwarf_expr_context *ctx)
  66. {
  67.   struct dwarf_gdbarch_types *types = gdbarch_data (ctx->gdbarch,
  68.                                                     dwarf_arch_cookie);
  69.   int ndx;

  71.   if (ctx->addr_size == 2)
  72.     ndx = 0;
  73.   else if (ctx->addr_size == 4)
  74.     ndx = 1;
  75.   else if (ctx->addr_size == 8)
  76.     ndx = 2;
  77.   else
  78.     error (_("Unsupported address size in DWARF expressions: %d bits"),
  79.            8 * ctx->addr_size);

  81.   if (types->dw_types[ndx] == NULL)
  82.     types->dw_types[ndx]
  83.       = arch_integer_type (ctx->gdbarch,
  84.                            8 * ctx->addr_size,
  85.                            0, "<signed DWARF address type>");

  87.   return types->dw_types[ndx];
  88. }

  90. /* Create a new context for the expression evaluator.  */

  92. struct dwarf_expr_context *
  93. ‌new_dwarf_expr_context (void)
  94. {
  95.   struct dwarf_expr_context *retval;

  97.   retval = xcalloc (1, sizeof (struct dwarf_expr_context));
  98.   retval->stack_len = 0;
  99.   retval->stack_allocated = 10;
  100.   retval->stack = xmalloc (retval->stack_allocated
  101.                            * sizeof (struct dwarf_stack_value));
  102.   retval->num_pieces = 0;
  103.   retval->pieces = 0;
  104.   retval->max_recursion_depth = 0x100;
  105.   return retval;
  106. }

  108. /* Release the memory allocated to CTX.  */

  110. void
  111. ‌free_dwarf_expr_context (struct dwarf_expr_context *ctx)
  112. {
  113.   xfree (ctx->stack);
  114.   xfree (ctx->pieces);
  115.   xfree (ctx);
  116. }

  118. /* Helper for make_cleanup_free_dwarf_expr_context.  */

  120. static void
  121. ‌free_dwarf_expr_context_cleanup (void *arg)
  122. {
  123.   free_dwarf_expr_context (arg);
  124. }

  126. /* Return a cleanup that calls free_dwarf_expr_context.  */

  128. struct cleanup *
  129. ‌make_cleanup_free_dwarf_expr_context (struct dwarf_expr_context *ctx)
  130. {
  131.   return make_cleanup (free_dwarf_expr_context_cleanup, ctx);
  132. }

  134. /* Expand the memory allocated to CTX's stack to contain at least
  135.    NEED more elements than are currently used.  */

  137. static void
  138. ‌dwarf_expr_grow_stack (struct dwarf_expr_context *ctx, size_t need)
  139. {
  140.   if (ctx->stack_len + need > ctx->stack_allocated)
  141.     {
  142.       size_t newlen = ctx->stack_len + need + 10;

  144.       ctx->stack = xrealloc (ctx->stack,
  145.                              newlen * sizeof (struct dwarf_stack_value));
  146.       ctx->stack_allocated = newlen;
  147.     }
  148. }

  150. /* Push VALUE onto CTX's stack.  */

  152. static void
  153. ‌dwarf_expr_push (struct dwarf_expr_context *ctx, struct value *value,
  154.                  int in_stack_memory)
  155. {
  156.   struct dwarf_stack_value *v;

  158.   dwarf_expr_grow_stack (ctx, 1);
  159.   v = &ctx->stack[ctx->stack_len++];
  160.   v->value = value;
  161.   v->in_stack_memory = in_stack_memory;
  162. }

  164. /* Push VALUE onto CTX's stack.  */

  166. void
  167. ‌dwarf_expr_push_address (struct dwarf_expr_context *ctx, CORE_ADDR value,
  168.                          int in_stack_memory)
  169. {
  170.   dwarf_expr_push (ctx,
  171.                    value_from_ulongest (dwarf_expr_address_type (ctx), value),
  172.                    in_stack_memory);
  173. }

  175. /* Pop the top item off of CTX's stack.  */

  177. static void
  178. ‌dwarf_expr_pop (struct dwarf_expr_context *ctx)
  179. {
  180.   if (ctx->stack_len <= 0)
  181.     error (_("dwarf expression stack underflow"));
  182.   ctx->stack_len--;
  183. }

  185. /* Retrieve the N'th item on CTX's stack.  */

  187. struct value *
  188. ‌dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n)
  189. {
  190.   if (ctx->stack_len <= n)
  191.      error (_("Asked for position %d of stack, "
  192.               "stack only has %d elements on it."),
  193.             n, ctx->stack_len);
  194.   return ctx->stack[ctx->stack_len - (1 + n)].value;
  195. }

  197. /* Require that TYPE be an integral type; throw an exception if not.  */

  199. static void
  200. ‌dwarf_require_integral (struct type *type)
  201. {
  202.   if (TYPE_CODE (type) != TYPE_CODE_INT
  203.       && TYPE_CODE (type) != TYPE_CODE_CHAR
  204.       && TYPE_CODE (type) != TYPE_CODE_BOOL)
  205.     error (_("integral type expected in DWARF expression"));
  206. }

  208. /* Return the unsigned form of TYPE.  TYPE is necessarily an integral
  209.    type.  */

  211. static struct type *
  212. ‌get_unsigned_type (struct gdbarch *gdbarch, struct type *type)
  213. {
  214.   switch (TYPE_LENGTH (type))
  215.     {
  216.     case 1:
  217.       return builtin_type (gdbarch)->builtin_uint8;
  218.     case 2:
  219.       return builtin_type (gdbarch)->builtin_uint16;
  220.     case 4:
  221.       return builtin_type (gdbarch)->builtin_uint32;
  222.     case 8:
  223.       return builtin_type (gdbarch)->builtin_uint64;
  224.     default:
  225.       error (_("no unsigned variant found for type, while evaluating "
  226.                "DWARF expression"));
  227.     }
  228. }

  230. /* Return the signed form of TYPE.  TYPE is necessarily an integral
  231.    type.  */

  233. static struct type *
  234. ‌get_signed_type (struct gdbarch *gdbarch, struct type *type)
  235. {
  236.   switch (TYPE_LENGTH (type))
  237.     {
  238.     case 1:
  239.       return builtin_type (gdbarch)->builtin_int8;
  240.     case 2:
  241.       return builtin_type (gdbarch)->builtin_int16;
  242.     case 4:
  243.       return builtin_type (gdbarch)->builtin_int32;
  244.     case 8:
  245.       return builtin_type (gdbarch)->builtin_int64;
  246.     default:
  247.       error (_("no signed variant found for type, while evaluating "
  248.                "DWARF expression"));
  249.     }
  250. }

  252. /* Retrieve the N'th item on CTX's stack, converted to an address.  */

  254. CORE_ADDR
  255. ‌dwarf_expr_fetch_address (struct dwarf_expr_context *ctx, int n)
  256. {
  257.   struct value *result_val = dwarf_expr_fetch (ctx, n);
  258.   enum bfd_endian byte_order = gdbarch_byte_order (ctx->gdbarch);
  259.   ULONGEST result;

  261.   dwarf_require_integral (value_type (result_val));
  262.   result = extract_unsigned_integer (value_contents (result_val),
  263.                                      TYPE_LENGTH (value_type (result_val)),
  264.                                      byte_order);

  266.   /* For most architectures, calling extract_unsigned_integer() alone
  267.      is sufficient for extracting an address.  However, some
  268.      architectures (e.g. MIPS) use signed addresses and using
  269.      extract_unsigned_integer() will not produce a correct
  270.      result.  Make sure we invoke gdbarch_integer_to_address()
  271.      for those architectures which require it.  */
  272.   if (gdbarch_integer_to_address_p (ctx->gdbarch))
  273.     {
  274.       gdb_byte *buf = alloca (ctx->addr_size);
  275.       struct type *int_type = get_unsigned_type (ctx->gdbarch,
  276.                                                  value_type (result_val));

  278.       store_unsigned_integer (buf, ctx->addr_size, byte_order, result);
  279.       return gdbarch_integer_to_address (ctx->gdbarch, int_type, buf);
  280.     }

  282.   return (CORE_ADDR) result;
  283. }

  285. /* Retrieve the in_stack_memory flag of the N'th item on CTX's stack.  */

  287. int
  288. ‌dwarf_expr_fetch_in_stack_memory (struct dwarf_expr_context *ctx, int n)
  289. {
  290.   if (ctx->stack_len <= n)
  291.      error (_("Asked for position %d of stack, "
  292.               "stack only has %d elements on it."),
  293.             n, ctx->stack_len);
  294.   return ctx->stack[ctx->stack_len - (1 + n)].in_stack_memory;
  295. }

  297. /* Return true if the expression stack is empty.  */

  299. static int
  300. ‌dwarf_expr_stack_empty_p (struct dwarf_expr_context *ctx)
  301. {
  302.   return ctx->stack_len == 0;
  303. }

  305. /* Add a new piece to CTX's piece list.  */
  306. static void
  307. ‌add_piece (struct dwarf_expr_context *ctx, ULONGEST size, ULONGEST offset)
  308. {
  309.   struct dwarf_expr_piece *p;

  311.   ctx->num_pieces++;

  313.   ctx->pieces = xrealloc (ctx->pieces,
  314.                           (ctx->num_pieces
  315.                            * sizeof (struct dwarf_expr_piece)));

  317.   p = &ctx->pieces[ctx->num_pieces - 1];
  318.   p->location = ctx->location;
  319.   p->size = size;
  320.   p->offset = offset;

  322.   if (p->location == DWARF_VALUE_LITERAL)
  323.     {
  324.       p->v.literal.data = ctx->data;
  325.       p->v.literal.length = ctx->len;
  326.     }
  327.   else if (dwarf_expr_stack_empty_p (ctx))
  328.     {
  329.       p->location = DWARF_VALUE_OPTIMIZED_OUT;
  330.       /* Also reset the context's location, for our callers.  This is
  331.          a somewhat strange approach, but this lets us avoid setting
  332.          the location to DWARF_VALUE_MEMORY in all the individual
  333.          cases in the evaluator.  */
  334.       ctx->location = DWARF_VALUE_OPTIMIZED_OUT;
  335.     }
  336.   else if (p->location == DWARF_VALUE_MEMORY)
  337.     {
  338.       p->v.mem.addr = dwarf_expr_fetch_address (ctx, 0);
  339.       p->v.mem.in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, 0);
  340.     }
  341.   else if (p->location == DWARF_VALUE_IMPLICIT_POINTER)
  342.     {
  343.       p->v.ptr.die.sect_off = ctx->len;
  344.       p->v.ptr.offset = value_as_long (dwarf_expr_fetch (ctx, 0));
  345.     }
  346.   else if (p->location == DWARF_VALUE_REGISTER)
  347.     p->v.regno = value_as_long (dwarf_expr_fetch (ctx, 0));
  348.   else
  349.     {
  350.       p->v.value = dwarf_expr_fetch (ctx, 0);
  351.     }
  352. }

  354. /* Evaluate the expression at ADDR (LEN bytes long) using the context
  355.    CTX.  */

  357. void
  358. ‌dwarf_expr_eval (struct dwarf_expr_context *ctx, const gdb_byte *addr,
  359.                  size_t len)
  360. {
  361.   int old_recursion_depth = ctx->recursion_depth;

  363.   execute_stack_op (ctx, addr, addr + len);

  365.   /* CTX RECURSION_DEPTH becomes invalid if an exception was thrown here.  */

  367.   gdb_assert (ctx->recursion_depth == old_recursion_depth);
  368. }

  370. /* Helper to read a uleb128 value or throw an error.  */

  372. const gdb_byte *
  373. ‌safe_read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
  374.                    uint64_t *r)
  375. {
  376.   buf = gdb_read_uleb128 (buf, buf_end, r);
  377.   if (buf == NULL)
  378.     error (_("DWARF expression error: ran off end of buffer reading uleb128 value"));
  379.   return buf;
  380. }

  382. /* Helper to read a sleb128 value or throw an error.  */

  384. const gdb_byte *
  385. ‌safe_read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
  386.                    int64_t *r)
  387. {
  388.   buf = gdb_read_sleb128 (buf, buf_end, r);
  389.   if (buf == NULL)
  390.     error (_("DWARF expression error: ran off end of buffer reading sleb128 value"));
  391.   return buf;
  392. }

  394. const gdb_byte *
  395. ‌safe_skip_leb128 (const gdb_byte *buf, const gdb_byte *buf_end)
  396. {
  397.   buf = gdb_skip_leb128 (buf, buf_end);
  398.   if (buf == NULL)
  399.     error (_("DWARF expression error: ran off end of buffer reading leb128 value"));
  400.   return buf;
  401. }


  404. /* Check that the current operator is either at the end of an
  405.    expression, or that it is followed by a composition operator.  */

  407. void
  408. ‌dwarf_expr_require_composition (const gdb_byte *op_ptr, const gdb_byte *op_end,
  409.                                 const char *op_name)
  410. {
  411.   /* It seems like DW_OP_GNU_uninit should be handled here.  However,
  412.      it doesn't seem to make sense for DW_OP_*_value, and it was not
  413.      checked at the other place that this function is called.  */
  414.   if (op_ptr != op_end && *op_ptr != DW_OP_piece && *op_ptr != DW_OP_bit_piece)
  415.     error (_("DWARF-2 expression error: `%s' operations must be "
  416.              "used either alone or in conjunction with DW_OP_piece "
  417.              "or DW_OP_bit_piece."),
  418.            op_name);
  419. }

  421. /* Return true iff the types T1 and T2 are "the same".  This only does
  422.    checks that might reasonably be needed to compare DWARF base
  423.    types.  */

  425. static int
  426. ‌base_types_equal_p (struct type *t1, struct type *t2)
  427. {
  428.   if (TYPE_CODE (t1) != TYPE_CODE (t2))
  429.     return 0;
  430.   if (TYPE_UNSIGNED (t1) != TYPE_UNSIGNED (t2))
  431.     return 0;
  432.   return TYPE_LENGTH (t1) == TYPE_LENGTH (t2);
  433. }

  435. /* A convenience function to call get_base_type on CTX and return the
  436.    result.  DIE is the DIE whose type we need.  SIZE is non-zero if
  437.    this function should verify that the resulting type has the correct
  438.    size.  */

  440. static struct type *
  441. ‌dwarf_get_base_type (struct dwarf_expr_context *ctx, cu_offset die, int size)
  442. {
  443.   struct type *result;

  445.   if (ctx->funcs->get_base_type)
  446.     {
  447.       result = ctx->funcs->get_base_type (ctx, die);
  448.       if (result == NULL)
  449.         error (_("Could not find type for DW_OP_GNU_const_type"));
  450.       if (size != 0 && TYPE_LENGTH (result) != size)
  451.         error (_("DW_OP_GNU_const_type has different sizes for type and data"));
  452.     }
  453.   else
  454.     /* Anything will do.  */
  455.     result = builtin_type (ctx->gdbarch)->builtin_int;

  457.   return result;
  458. }

  460. /* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_reg* return the
  461.    DWARF register number.  Otherwise return -1.  */

  463. int
  464. ‌dwarf_block_to_dwarf_reg (const gdb_byte *buf, const gdb_byte *buf_end)
  465. {
  466.   uint64_t dwarf_reg;

  468.   if (buf_end <= buf)
  469.     return -1;
  470.   if (*buf >= DW_OP_reg0 && *buf <= DW_OP_reg31)
  471.     {
  472.       if (buf_end - buf != 1)
  473.         return -1;
  474.       return *buf - DW_OP_reg0;
  475.     }

  477.   if (*buf == DW_OP_GNU_regval_type)
  478.     {
  479.       buf++;
  480.       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
  481.       if (buf == NULL)
  482.         return -1;
  483.       buf = gdb_skip_leb128 (buf, buf_end);
  484.       if (buf == NULL)
  485.         return -1;
  486.     }
  487.   else if (*buf == DW_OP_regx)
  488.     {
  489.       buf++;
  490.       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
  491.       if (buf == NULL)
  492.         return -1;
  493.     }
  494.   else
  495.     return -1;
  496.   if (buf != buf_end || (int) dwarf_reg != dwarf_reg)
  497.     return -1;
  498.   return dwarf_reg;
  499. }

  501. /* If <BUF..BUF_END] contains DW_FORM_block* with just DW_OP_breg*(0) and
  502.    DW_OP_deref* return the DWARF register number.  Otherwise return -1.
  503.    DEREF_SIZE_RETURN contains -1 for DW_OP_deref; otherwise it contains the
  504.    size from DW_OP_deref_size.  */

  506. int
  507. ‌dwarf_block_to_dwarf_reg_deref (const gdb_byte *buf, const gdb_byte *buf_end,
  508.                                 CORE_ADDR *deref_size_return)
  509. {
  510.   uint64_t dwarf_reg;
  511.   int64_t offset;

  513.   if (buf_end <= buf)
  514.     return -1;

  516.   if (*buf >= DW_OP_breg0 && *buf <= DW_OP_breg31)
  517.     {
  518.       dwarf_reg = *buf - DW_OP_breg0;
  519.       buf++;
  520.       if (buf >= buf_end)
  521.         return -1;
  522.     }
  523.   else if (*buf == DW_OP_bregx)
  524.     {
  525.       buf++;
  526.       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
  527.       if (buf == NULL)
  528.         return -1;
  529.       if ((int) dwarf_reg != dwarf_reg)
  530.        return -1;
  531.     }
  532.   else
  533.     return -1;

  535.   buf = gdb_read_sleb128 (buf, buf_end, &offset);
  536.   if (buf == NULL)
  537.     return -1;
  538.   if (offset != 0)
  539.     return -1;

  541.   if (*buf == DW_OP_deref)
  542.     {
  543.       buf++;
  544.       *deref_size_return = -1;
  545.     }
  546.   else if (*buf == DW_OP_deref_size)
  547.     {
  548.       buf++;
  549.       if (buf >= buf_end)
  550.        return -1;
  551.       *deref_size_return = *buf++;
  552.     }
  553.   else
  554.     return -1;

  556.   if (buf != buf_end)
  557.     return -1;

  559.   return dwarf_reg;
  560. }

  562. /* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_fbreg(X) fill
  563.    in FB_OFFSET_RETURN with the X offset and return 1.  Otherwise return 0.  */

  565. int
  566. ‌dwarf_block_to_fb_offset (const gdb_byte *buf, const gdb_byte *buf_end,
  567.                           CORE_ADDR *fb_offset_return)
  568. {
  569.   int64_t fb_offset;

  571.   if (buf_end <= buf)
  572.     return 0;

  574.   if (*buf != DW_OP_fbreg)
  575.     return 0;
  576.   buf++;

  578.   buf = gdb_read_sleb128 (buf, buf_end, &fb_offset);
  579.   if (buf == NULL)
  580.     return 0;
  581.   *fb_offset_return = fb_offset;
  582.   if (buf != buf_end || fb_offset != (LONGEST) *fb_offset_return)
  583.     return 0;

  585.   return 1;
  586. }

  588. /* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_bregSP(X) fill
  589.    in SP_OFFSET_RETURN with the X offset and return 1.  Otherwise return 0.
  590.    The matched SP register number depends on GDBARCH.  */

  592. int
  593. ‌dwarf_block_to_sp_offset (struct gdbarch *gdbarch, const gdb_byte *buf,
  594.                           const gdb_byte *buf_end, CORE_ADDR *sp_offset_return)
  595. {
  596.   uint64_t dwarf_reg;
  597.   int64_t sp_offset;

  599.   if (buf_end <= buf)
  600.     return 0;
  601.   if (*buf >= DW_OP_breg0 && *buf <= DW_OP_breg31)
  602.     {
  603.       dwarf_reg = *buf - DW_OP_breg0;
  604.       buf++;
  605.     }
  606.   else
  607.     {
  608.       if (*buf != DW_OP_bregx)
  609.        return 0;
  610.       buf++;
  611.       buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
  612.       if (buf == NULL)
  613.         return 0;
  614.     }

  616.   if (gdbarch_dwarf2_reg_to_regnum (gdbarch, dwarf_reg)
  617.       != gdbarch_sp_regnum (gdbarch))
  618.     return 0;

  620.   buf = gdb_read_sleb128 (buf, buf_end, &sp_offset);
  621.   if (buf == NULL)
  622.     return 0;
  623.   *sp_offset_return = sp_offset;
  624.   if (buf != buf_end || sp_offset != (LONGEST) *sp_offset_return)
  625.     return 0;

  627.   return 1;
  628. }

  630. /* The engine for the expression evaluator.  Using the context in CTX,
  631.    evaluate the expression between OP_PTR and OP_END.  */

  633. static void
  634. ‌execute_stack_op (struct dwarf_expr_context *ctx,
  635.                   const gdb_byte *op_ptr, const gdb_byte *op_end)
  636. {
  637.   enum bfd_endian byte_order = gdbarch_byte_order (ctx->gdbarch);
  638.   /* Old-style "untyped" DWARF values need special treatment in a
  639.      couple of places, specifically DW_OP_mod and DW_OP_shr.  We need
  640.      a special type for these values so we can distinguish them from
  641.      values that have an explicit type, because explicitly-typed
  642.      values do not need special treatment.  This special type must be
  643.      different (in the `==' sense) from any base type coming from the
  644.      CU.  */
  645.   struct type *address_type = dwarf_expr_address_type (ctx);

  647.   ctx->location = DWARF_VALUE_MEMORY;
  648.   ctx->initialized = 1;  /* Default is initialized.  */

  650.   if (ctx->recursion_depth > ctx->max_recursion_depth)
  651.     error (_("DWARF-2 expression error: Loop detected (%d)."),
  652.            ctx->recursion_depth);
  653.   ctx->recursion_depth++;

  655.   while (op_ptr < op_end)
  656.     {
  657.       enum dwarf_location_atom op = *op_ptr++;
  658.       ULONGEST result;
  659.       /* Assume the value is not in stack memory.
  660.          Code that knows otherwise sets this to 1.
  661.          Some arithmetic on stack addresses can probably be assumed to still
  662.          be a stack address, but we skip this complication for now.
  663.          This is just an optimization, so it's always ok to punt
  664.          and leave this as 0.  */
  665.       int in_stack_memory = 0;
  666.       uint64_t uoffset, reg;
  667.       int64_t offset;
  668.       struct value *result_val = NULL;

  670.       /* The DWARF expression might have a bug causing an infinite
  671.          loop.  In that case, quitting is the only way out.  */
  672.       QUIT;

  674.       switch (op)
  675.         {
  676.         case DW_OP_lit0:
  677.         case DW_OP_lit1:
  678.         case DW_OP_lit2:
  679.         case DW_OP_lit3:
  680.         case DW_OP_lit4:
  681.         case DW_OP_lit5:
  682.         case DW_OP_lit6:
  683.         case DW_OP_lit7:
  684.         case DW_OP_lit8:
  685.         case DW_OP_lit9:
  686.         case DW_OP_lit10:
  687.         case DW_OP_lit11:
  688.         case DW_OP_lit12:
  689.         case DW_OP_lit13:
  690.         case DW_OP_lit14:
  691.         case DW_OP_lit15:
  692.         case DW_OP_lit16:
  693.         case DW_OP_lit17:
  694.         case DW_OP_lit18:
  695.         case DW_OP_lit19:
  696.         case DW_OP_lit20:
  697.         case DW_OP_lit21:
  698.         case DW_OP_lit22:
  699.         case DW_OP_lit23:
  700.         case DW_OP_lit24:
  701.         case DW_OP_lit25:
  702.         case DW_OP_lit26:
  703.         case DW_OP_lit27:
  704.         case DW_OP_lit28:
  705.         case DW_OP_lit29:
  706.         case DW_OP_lit30:
  707.         case DW_OP_lit31:
  708.           result = op - DW_OP_lit0;
  709.           result_val = value_from_ulongest (address_type, result);
  710.           break;

  712.         case DW_OP_addr:
  713.           result = extract_unsigned_integer (op_ptr,
  714.                                              ctx->addr_size, byte_order);
  715.           op_ptr += ctx->addr_size;
  716.           /* Some versions of GCC emit DW_OP_addr before
  717.              DW_OP_GNU_push_tls_address.  In this case the value is an
  718.              index, not an address.  We don't support things like
  719.              branching between the address and the TLS op.  */
  720.           if (op_ptr >= op_end || *op_ptr != DW_OP_GNU_push_tls_address)
  721.             result += ctx->offset;
  722.           result_val = value_from_ulongest (address_type, result);
  723.           break;

  725.         case DW_OP_GNU_addr_index:
  726.           op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
  727.           result = (ctx->funcs->get_addr_index) (ctx->baton, uoffset);
  728.           result += ctx->offset;
  729.           result_val = value_from_ulongest (address_type, result);
  730.           break;
  731.         case DW_OP_GNU_const_index:
  732.           op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
  733.           result = (ctx->funcs->get_addr_index) (ctx->baton, uoffset);
  734.           result_val = value_from_ulongest (address_type, result);
  735.           break;

  737.         case DW_OP_const1u:
  738.           result = extract_unsigned_integer (op_ptr, 1, byte_order);
  739.           result_val = value_from_ulongest (address_type, result);
  740.           op_ptr += 1;
  741.           break;
  742.         case DW_OP_const1s:
  743.           result = extract_signed_integer (op_ptr, 1, byte_order);
  744.           result_val = value_from_ulongest (address_type, result);
  745.           op_ptr += 1;
  746.           break;
  747.         case DW_OP_const2u:
  748.           result = extract_unsigned_integer (op_ptr, 2, byte_order);
  749.           result_val = value_from_ulongest (address_type, result);
  750.           op_ptr += 2;
  751.           break;
  752.         case DW_OP_const2s:
  753.           result = extract_signed_integer (op_ptr, 2, byte_order);
  754.           result_val = value_from_ulongest (address_type, result);
  755.           op_ptr += 2;
  756.           break;
  757.         case DW_OP_const4u:
  758.           result = extract_unsigned_integer (op_ptr, 4, byte_order);
  759.           result_val = value_from_ulongest (address_type, result);
  760.           op_ptr += 4;
  761.           break;
  762.         case DW_OP_const4s:
  763.           result = extract_signed_integer (op_ptr, 4, byte_order);
  764.           result_val = value_from_ulongest (address_type, result);
  765.           op_ptr += 4;
  766.           break;
  767.         case DW_OP_const8u:
  768.           result = extract_unsigned_integer (op_ptr, 8, byte_order);
  769.           result_val = value_from_ulongest (address_type, result);
  770.           op_ptr += 8;
  771.           break;
  772.         case DW_OP_const8s:
  773.           result = extract_signed_integer (op_ptr, 8, byte_order);
  774.           result_val = value_from_ulongest (address_type, result);
  775.           op_ptr += 8;
  776.           break;
  777.         case DW_OP_constu:
  778.           op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
  779.           result = uoffset;
  780.           result_val = value_from_ulongest (address_type, result);
  781.           break;
  782.         case DW_OP_consts:
  783.           op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
  784.           result = offset;
  785.           result_val = value_from_ulongest (address_type, result);
  786.           break;

  788.         /* The DW_OP_reg operations are required to occur alone in
  789.            location expressions.  */
  790.         case DW_OP_reg0:
  791.         case DW_OP_reg1:
  792.         case DW_OP_reg2:
  793.         case DW_OP_reg3:
  794.         case DW_OP_reg4:
  795.         case DW_OP_reg5:
  796.         case DW_OP_reg6:
  797.         case DW_OP_reg7:
  798.         case DW_OP_reg8:
  799.         case DW_OP_reg9:
  800.         case DW_OP_reg10:
  801.         case DW_OP_reg11:
  802.         case DW_OP_reg12:
  803.         case DW_OP_reg13:
  804.         case DW_OP_reg14:
  805.         case DW_OP_reg15:
  806.         case DW_OP_reg16:
  807.         case DW_OP_reg17:
  808.         case DW_OP_reg18:
  809.         case DW_OP_reg19:
  810.         case DW_OP_reg20:
  811.         case DW_OP_reg21:
  812.         case DW_OP_reg22:
  813.         case DW_OP_reg23:
  814.         case DW_OP_reg24:
  815.         case DW_OP_reg25:
  816.         case DW_OP_reg26:
  817.         case DW_OP_reg27:
  818.         case DW_OP_reg28:
  819.         case DW_OP_reg29:
  820.         case DW_OP_reg30:
  821.         case DW_OP_reg31:
  822.           if (op_ptr != op_end
  823.               && *op_ptr != DW_OP_piece
  824.               && *op_ptr != DW_OP_bit_piece
  825.               && *op_ptr != DW_OP_GNU_uninit)
  826.             error (_("DWARF-2 expression error: DW_OP_reg operations must be "
  827.                      "used either alone or in conjunction with DW_OP_piece "
  828.                      "or DW_OP_bit_piece."));

  830.           result = op - DW_OP_reg0;
  831.           result_val = value_from_ulongest (address_type, result);
  832.           ctx->location = DWARF_VALUE_REGISTER;
  833.           break;

  835.         case DW_OP_regx:
  836.           op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
  837.           dwarf_expr_require_composition (op_ptr, op_end, "DW_OP_regx");

  839.           result = reg;
  840.           result_val = value_from_ulongest (address_type, result);
  841.           ctx->location = DWARF_VALUE_REGISTER;
  842.           break;

  844.         case DW_OP_implicit_value:
  845.           {
  846.             uint64_t len;

  848.             op_ptr = safe_read_uleb128 (op_ptr, op_end, &len);
  849.             if (op_ptr + len > op_end)
  850.               error (_("DW_OP_implicit_value: too few bytes available."));
  851.             ctx->len = len;
  852.             ctx->data = op_ptr;
  853.             ctx->location = DWARF_VALUE_LITERAL;
  854.             op_ptr += len;
  855.             dwarf_expr_require_composition (op_ptr, op_end,
  856.                                             "DW_OP_implicit_value");
  857.           }
  858.           goto no_push;

  860.         case DW_OP_stack_value:
  861.           ctx->location = DWARF_VALUE_STACK;
  862.           dwarf_expr_require_composition (op_ptr, op_end, "DW_OP_stack_value");
  863.           goto no_push;

  865.         case DW_OP_GNU_implicit_pointer:
  866.           {
  867.             int64_t len;

  869.             if (ctx->ref_addr_size == -1)
  870.               error (_("DWARF-2 expression error: DW_OP_GNU_implicit_pointer "
  871.                        "is not allowed in frame context"));

  873.             /* The referred-to DIE of sect_offset kind.  */
  874.             ctx->len = extract_unsigned_integer (op_ptr, ctx->ref_addr_size,
  875.                                                  byte_order);
  876.             op_ptr += ctx->ref_addr_size;

  878.             /* The byte offset into the data.  */
  879.             op_ptr = safe_read_sleb128 (op_ptr, op_end, &len);
  880.             result = (ULONGEST) len;
  881.             result_val = value_from_ulongest (address_type, result);

  883.             ctx->location = DWARF_VALUE_IMPLICIT_POINTER;
  884.             dwarf_expr_require_composition (op_ptr, op_end,
  885.                                             "DW_OP_GNU_implicit_pointer");
  886.           }
  887.           break;

  889.         case DW_OP_breg0:
  890.         case DW_OP_breg1:
  891.         case DW_OP_breg2:
  892.         case DW_OP_breg3:
  893.         case DW_OP_breg4:
  894.         case DW_OP_breg5:
  895.         case DW_OP_breg6:
  896.         case DW_OP_breg7:
  897.         case DW_OP_breg8:
  898.         case DW_OP_breg9:
  899.         case DW_OP_breg10:
  900.         case DW_OP_breg11:
  901.         case DW_OP_breg12:
  902.         case DW_OP_breg13:
  903.         case DW_OP_breg14:
  904.         case DW_OP_breg15:
  905.         case DW_OP_breg16:
  906.         case DW_OP_breg17:
  907.         case DW_OP_breg18:
  908.         case DW_OP_breg19:
  909.         case DW_OP_breg20:
  910.         case DW_OP_breg21:
  911.         case DW_OP_breg22:
  912.         case DW_OP_breg23:
  913.         case DW_OP_breg24:
  914.         case DW_OP_breg25:
  915.         case DW_OP_breg26:
  916.         case DW_OP_breg27:
  917.         case DW_OP_breg28:
  918.         case DW_OP_breg29:
  919.         case DW_OP_breg30:
  920.         case DW_OP_breg31:
  921.           {
  922.             op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
  923.             result = (ctx->funcs->read_addr_from_reg) (ctx->baton,
  924.                                                        op - DW_OP_breg0);
  925.             result += offset;
  926.             result_val = value_from_ulongest (address_type, result);
  927.           }
  928.           break;
  929.         case DW_OP_bregx:
  930.           {
  931.             op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
  932.             op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
  933.             result = (ctx->funcs->read_addr_from_reg) (ctx->baton, reg);
  934.             result += offset;
  935.             result_val = value_from_ulongest (address_type, result);
  936.           }
  937.           break;
  938.         case DW_OP_fbreg:
  939.           {
  940.             const gdb_byte *datastart;
  941.             size_t datalen;
  942.             unsigned int before_stack_len;

  944.             op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
  945.             /* Rather than create a whole new context, we simply
  946.                record the stack length before execution, then reset it
  947.                afterwards, effectively erasing whatever the recursive
  948.                call put there.  */
  949.             before_stack_len = ctx->stack_len;
  950.             /* FIXME: cagney/2003-03-26: This code should be using
  951.                get_frame_base_address(), and then implement a dwarf2
  952.                specific this_base method.  */
  953.             (ctx->funcs->get_frame_base) (ctx->baton, &datastart, &datalen);
  954.             dwarf_expr_eval (ctx, datastart, datalen);
  955.             if (ctx->location == DWARF_VALUE_MEMORY)
  956.               result = dwarf_expr_fetch_address (ctx, 0);
  957.             else if (ctx->location == DWARF_VALUE_REGISTER)
  958.               result = (ctx->funcs->read_addr_from_reg)
  959.                           (ctx->baton,
  960.                            value_as_long (dwarf_expr_fetch (ctx, 0)));
  961.             else
  962.               error (_("Not implemented: computing frame "
  963.                        "base using explicit value operator"));
  964.             result = result + offset;
  965.             result_val = value_from_ulongest (address_type, result);
  966.             in_stack_memory = 1;
  967.             ctx->stack_len = before_stack_len;
  968.             ctx->location = DWARF_VALUE_MEMORY;
  969.           }
  970.           break;

  972.         case DW_OP_dup:
  973.           result_val = dwarf_expr_fetch (ctx, 0);
  974.           in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, 0);
  975.           break;

  977.         case DW_OP_drop:
  978.           dwarf_expr_pop (ctx);
  979.           goto no_push;

  981.         case DW_OP_pick:
  982.           offset = *op_ptr++;
  983.           result_val = dwarf_expr_fetch (ctx, offset);
  984.           in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, offset);
  985.           break;

  987.         case DW_OP_swap:
  988.           {
  989.             struct dwarf_stack_value t1, t2;

  991.             if (ctx->stack_len < 2)
  992.                error (_("Not enough elements for "
  993.                         "DW_OP_swap.  Need 2, have %d."),
  994.                       ctx->stack_len);
  995.             t1 = ctx->stack[ctx->stack_len - 1];
  996.             t2 = ctx->stack[ctx->stack_len - 2];
  997.             ctx->stack[ctx->stack_len - 1] = t2;
  998.             ctx->stack[ctx->stack_len - 2] = t1;
  999.             goto no_push;
  1000.           }

  1002.         case DW_OP_over:
  1003.           result_val = dwarf_expr_fetch (ctx, 1);
  1004.           in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, 1);
  1005.           break;

  1007.         case DW_OP_rot:
  1008.           {
  1009.             struct dwarf_stack_value t1, t2, t3;

  1011.             if (ctx->stack_len < 3)
  1012.                error (_("Not enough elements for "
  1013.                         "DW_OP_rot.  Need 3, have %d."),
  1014.                       ctx->stack_len);
  1015.             t1 = ctx->stack[ctx->stack_len - 1];
  1016.             t2 = ctx->stack[ctx->stack_len - 2];
  1017.             t3 = ctx->stack[ctx->stack_len - 3];
  1018.             ctx->stack[ctx->stack_len - 1] = t2;
  1019.             ctx->stack[ctx->stack_len - 2] = t3;
  1020.             ctx->stack[ctx->stack_len - 3] = t1;
  1021.             goto no_push;
  1022.           }

  1024.         case DW_OP_deref:
  1025.         case DW_OP_deref_size:
  1026.         case DW_OP_GNU_deref_type:
  1027.           {
  1028.             int addr_size = (op == DW_OP_deref ? ctx->addr_size : *op_ptr++);
  1029.             gdb_byte *buf = alloca (addr_size);
  1030.             CORE_ADDR addr = dwarf_expr_fetch_address (ctx, 0);
  1031.             struct type *type;

  1033.             dwarf_expr_pop (ctx);

  1035.             if (op == DW_OP_GNU_deref_type)
  1036.               {
  1037.                 cu_offset type_die;

  1039.                 op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
  1040.                 type_die.cu_off = uoffset;
  1041.                 type = dwarf_get_base_type (ctx, type_die, 0);
  1042.               }
  1043.             else
  1044.               type = address_type;

  1046.             (ctx->funcs->read_mem) (ctx->baton, buf, addr, addr_size);

  1048.             /* If the size of the object read from memory is different
  1049.                from the type length, we need to zero-extend it.  */
  1050.             if (TYPE_LENGTH (type) != addr_size)
  1051.               {
  1052.                 ULONGEST result =
  1053.                   extract_unsigned_integer (buf, addr_size, byte_order);

  1055.                 buf = alloca (TYPE_LENGTH (type));
  1056.                 store_unsigned_integer (buf, TYPE_LENGTH (type),
  1057.                                         byte_order, result);
  1058.               }

  1060.             result_val = value_from_contents_and_address (type, buf, addr);
  1061.             break;
  1062.           }

  1064.         case DW_OP_abs:
  1065.         case DW_OP_neg:
  1066.         case DW_OP_not:
  1067.         case DW_OP_plus_uconst:
  1068.           {
  1069.             /* Unary operations.  */
  1070.             result_val = dwarf_expr_fetch (ctx, 0);
  1071.             dwarf_expr_pop (ctx);

  1073.             switch (op)
  1074.               {
  1075.               case DW_OP_abs:
  1076.                 if (value_less (result_val,
  1077.                                 value_zero (value_type (result_val), not_lval)))
  1078.                   result_val = value_neg (result_val);
  1079.                 break;
  1080.               case DW_OP_neg:
  1081.                 result_val = value_neg (result_val);
  1082.                 break;
  1083.               case DW_OP_not:
  1084.                 dwarf_require_integral (value_type (result_val));
  1085.                 result_val = value_complement (result_val);
  1086.                 break;
  1087.               case DW_OP_plus_uconst:
  1088.                 dwarf_require_integral (value_type (result_val));
  1089.                 result = value_as_long (result_val);
  1090.                 op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
  1091.                 result += reg;
  1092.                 result_val = value_from_ulongest (address_type, result);
  1093.                 break;
  1094.               }
  1095.           }
  1096.           break;

  1098.         case DW_OP_and:
  1099.         case DW_OP_div:
  1100.         case DW_OP_minus:
  1101.         case DW_OP_mod:
  1102.         case DW_OP_mul:
  1103.         case DW_OP_or:
  1104.         case DW_OP_plus:
  1105.         case DW_OP_shl:
  1106.         case DW_OP_shr:
  1107.         case DW_OP_shra:
  1108.         case DW_OP_xor:
  1109.         case DW_OP_le:
  1110.         case DW_OP_ge:
  1111.         case DW_OP_eq:
  1112.         case DW_OP_lt:
  1113.         case DW_OP_gt:
  1114.         case DW_OP_ne:
  1115.           {
  1116.             /* Binary operations.  */
  1117.             struct value *first, *second;

  1119.             second = dwarf_expr_fetch (ctx, 0);
  1120.             dwarf_expr_pop (ctx);

  1122.             first = dwarf_expr_fetch (ctx, 0);
  1123.             dwarf_expr_pop (ctx);

  1125.             if (! base_types_equal_p (value_type (first), value_type (second)))
  1126.               error (_("Incompatible types on DWARF stack"));

  1128.             switch (op)
  1129.               {
  1130.               case DW_OP_and:
  1131.                 dwarf_require_integral (value_type (first));
  1132.                 dwarf_require_integral (value_type (second));
  1133.                 result_val = value_binop (first, second, BINOP_BITWISE_AND);
  1134.                 break;
  1135.               case DW_OP_div:
  1136.                 result_val = value_binop (first, second, BINOP_DIV);
  1137.                 break;
  1138.               case DW_OP_minus:
  1139.                 result_val = value_binop (first, second, BINOP_SUB);
  1140.                 break;
  1141.               case DW_OP_mod:
  1142.                 {
  1143.                   int cast_back = 0;
  1144.                   struct type *orig_type = value_type (first);

  1146.                   /* We have to special-case "old-style" untyped values
  1147.                      -- these must have mod computed using unsigned
  1148.                      math.  */
  1149.                   if (orig_type == address_type)
  1150.                     {
  1151.                       struct type *utype
  1152.                         = get_unsigned_type (ctx->gdbarch, orig_type);

  1154.                       cast_back = 1;
  1155.                       first = value_cast (utype, first);
  1156.                       second = value_cast (utype, second);
  1157.                     }
  1158.                   /* Note that value_binop doesn't handle float or
  1159.                      decimal float here.  This seems unimportant.  */
  1160.                   result_val = value_binop (first, second, BINOP_MOD);
  1161.                   if (cast_back)
  1162.                     result_val = value_cast (orig_type, result_val);
  1163.                 }
  1164.                 break;
  1165.               case DW_OP_mul:
  1166.                 result_val = value_binop (first, second, BINOP_MUL);
  1167.                 break;
  1168.               case DW_OP_or:
  1169.                 dwarf_require_integral (value_type (first));
  1170.                 dwarf_require_integral (value_type (second));
  1171.                 result_val = value_binop (first, second, BINOP_BITWISE_IOR);
  1172.                 break;
  1173.               case DW_OP_plus:
  1174.                 result_val = value_binop (first, second, BINOP_ADD);
  1175.                 break;
  1176.               case DW_OP_shl:
  1177.                 dwarf_require_integral (value_type (first));
  1178.                 dwarf_require_integral (value_type (second));
  1179.                 result_val = value_binop (first, second, BINOP_LSH);
  1180.                 break;
  1181.               case DW_OP_shr:
  1182.                 dwarf_require_integral (value_type (first));
  1183.                 dwarf_require_integral (value_type (second));
  1184.                 if (!TYPE_UNSIGNED (value_type (first)))
  1185.                   {
  1186.                     struct type *utype
  1187.                       = get_unsigned_type (ctx->gdbarch, value_type (first));

  1189.                     first = value_cast (utype, first);
  1190.                   }

  1192.                 result_val = value_binop (first, second, BINOP_RSH);
  1193.                 /* Make sure we wind up with the same type we started
  1194.                    with.  */
  1195.                 if (value_type (result_val) != value_type (second))
  1196.                   result_val = value_cast (value_type (second), result_val);
  1197.                 break;
  1198.               case DW_OP_shra:
  1199.                 dwarf_require_integral (value_type (first));
  1200.                 dwarf_require_integral (value_type (second));
  1201.                 if (TYPE_UNSIGNED (value_type (first)))
  1202.                   {
  1203.                     struct type *stype
  1204.                       = get_signed_type (ctx->gdbarch, value_type (first));

  1206.                     first = value_cast (stype, first);
  1207.                   }

  1209.                 result_val = value_binop (first, second, BINOP_RSH);
  1210.                 /* Make sure we wind up with the same type we started
  1211.                    with.  */
  1212.                 if (value_type (result_val) != value_type (second))
  1213.                   result_val = value_cast (value_type (second), result_val);
  1214.                 break;
  1215.               case DW_OP_xor:
  1216.                 dwarf_require_integral (value_type (first));
  1217.                 dwarf_require_integral (value_type (second));
  1218.                 result_val = value_binop (first, second, BINOP_BITWISE_XOR);
  1219.                 break;
  1220.               case DW_OP_le:
  1221.                 /* A <= B is !(B < A).  */
  1222.                 result = ! value_less (second, first);
  1223.                 result_val = value_from_ulongest (address_type, result);
  1224.                 break;
  1225.               case DW_OP_ge:
  1226.                 /* A >= B is !(A < B).  */
  1227.                 result = ! value_less (first, second);
  1228.                 result_val = value_from_ulongest (address_type, result);
  1229.                 break;
  1230.               case DW_OP_eq:
  1231.                 result = value_equal (first, second);
  1232.                 result_val = value_from_ulongest (address_type, result);
  1233.                 break;
  1234.               case DW_OP_lt:
  1235.                 result = value_less (first, second);
  1236.                 result_val = value_from_ulongest (address_type, result);
  1237.                 break;
  1238.               case DW_OP_gt:
  1239.                 /* A > B is B < A.  */
  1240.                 result = value_less (second, first);
  1241.                 result_val = value_from_ulongest (address_type, result);
  1242.                 break;
  1243.               case DW_OP_ne:
  1244.                 result = ! value_equal (first, second);
  1245.                 result_val = value_from_ulongest (address_type, result);
  1246.                 break;
  1247.               default:
  1248.                 internal_error (__FILE__, __LINE__,
  1249.                                 _("Can't be reached."));
  1250.               }
  1251.           }
  1252.           break;

  1254.         case DW_OP_call_frame_cfa:
  1255.           result = (ctx->funcs->get_frame_cfa) (ctx->baton);
  1256.           result_val = value_from_ulongest (address_type, result);
  1257.           in_stack_memory = 1;
  1258.           break;

  1260.         case DW_OP_GNU_push_tls_address:
  1261.           /* Variable is at a constant offset in the thread-local
  1262.           storage block into the objfile for the current thread and
  1263.           the dynamic linker module containing this expression.  Here
  1264.           we return returns the offset from that base.  The top of the
  1265.           stack has the offset from the beginning of the thread
  1266.           control block at which the variable is located.  Nothing
  1267.           should follow this operator, so the top of stack would be
  1268.           returned.  */
  1269.           result = value_as_long (dwarf_expr_fetch (ctx, 0));
  1270.           dwarf_expr_pop (ctx);
  1271.           result = (ctx->funcs->get_tls_address) (ctx->baton, result);
  1272.           result_val = value_from_ulongest (address_type, result);
  1273.           break;

  1275.         case DW_OP_skip:
  1276.           offset = extract_signed_integer (op_ptr, 2, byte_order);
  1277.           op_ptr += 2;
  1278.           op_ptr += offset;
  1279.           goto no_push;

  1281.         case DW_OP_bra:
  1282.           {
  1283.             struct value *val;

  1285.             offset = extract_signed_integer (op_ptr, 2, byte_order);
  1286.             op_ptr += 2;
  1287.             val = dwarf_expr_fetch (ctx, 0);
  1288.             dwarf_require_integral (value_type (val));
  1289.             if (value_as_long (val) != 0)
  1290.               op_ptr += offset;
  1291.             dwarf_expr_pop (ctx);
  1292.           }
  1293.           goto no_push;

  1295.         case DW_OP_nop:
  1296.           goto no_push;

  1298.         case DW_OP_piece:
  1299.           {
  1300.             uint64_t size;

  1302.             /* Record the piece.  */
  1303.             op_ptr = safe_read_uleb128 (op_ptr, op_end, &size);
  1304.             add_piece (ctx, 8 * size, 0);

  1306.             /* Pop off the address/regnum, and reset the location
  1307.                type.  */
  1308.             if (ctx->location != DWARF_VALUE_LITERAL
  1309.                 && ctx->location != DWARF_VALUE_OPTIMIZED_OUT)
  1310.               dwarf_expr_pop (ctx);
  1311.             ctx->location = DWARF_VALUE_MEMORY;
  1312.           }
  1313.           goto no_push;

  1315.         case DW_OP_bit_piece:
  1316.           {
  1317.             uint64_t size, offset;

  1319.             /* Record the piece.  */
  1320.             op_ptr = safe_read_uleb128 (op_ptr, op_end, &size);
  1321.             op_ptr = safe_read_uleb128 (op_ptr, op_end, &offset);
  1322.             add_piece (ctx, size, offset);

  1324.             /* Pop off the address/regnum, and reset the location
  1325.                type.  */
  1326.             if (ctx->location != DWARF_VALUE_LITERAL
  1327.                 && ctx->location != DWARF_VALUE_OPTIMIZED_OUT)
  1328.               dwarf_expr_pop (ctx);
  1329.             ctx->location = DWARF_VALUE_MEMORY;
  1330.           }
  1331.           goto no_push;

  1333.         case DW_OP_GNU_uninit:
  1334.           if (op_ptr != op_end)
  1335.             error (_("DWARF-2 expression error: DW_OP_GNU_uninit must always "
  1336.                    "be the very last op."));

  1338.           ctx->initialized = 0;
  1339.           goto no_push;

  1341.         case DW_OP_call2:
  1342.           {
  1343.             cu_offset offset;

  1345.             offset.cu_off = extract_unsigned_integer (op_ptr, 2, byte_order);
  1346.             op_ptr += 2;
  1347.             ctx->funcs->dwarf_call (ctx, offset);
  1348.           }
  1349.           goto no_push;

  1351.         case DW_OP_call4:
  1352.           {
  1353.             cu_offset offset;

  1355.             offset.cu_off = extract_unsigned_integer (op_ptr, 4, byte_order);
  1356.             op_ptr += 4;
  1357.             ctx->funcs->dwarf_call (ctx, offset);
  1358.           }
  1359.           goto no_push;

  1361.         case DW_OP_GNU_entry_value:
  1362.           {
  1363.             uint64_t len;
  1364.             CORE_ADDR deref_size;
  1365.             union call_site_parameter_u kind_u;

  1367.             op_ptr = safe_read_uleb128 (op_ptr, op_end, &len);
  1368.             if (op_ptr + len > op_end)
  1369.               error (_("DW_OP_GNU_entry_value: too few bytes available."));

  1371.             kind_u.dwarf_reg = dwarf_block_to_dwarf_reg (op_ptr, op_ptr + len);
  1372.             if (kind_u.dwarf_reg != -1)
  1373.               {
  1374.                 op_ptr += len;
  1375.                 ctx->funcs->push_dwarf_reg_entry_value (ctx,
  1376.                                                   CALL_SITE_PARAMETER_DWARF_REG,
  1377.                                                         kind_u,
  1378.                                                         -1 /* deref_size */);
  1379.                 goto no_push;
  1380.               }

  1382.             kind_u.dwarf_reg = dwarf_block_to_dwarf_reg_deref (op_ptr,
  1383.                                                                op_ptr + len,
  1384.                                                                &deref_size);
  1385.             if (kind_u.dwarf_reg != -1)
  1386.               {
  1387.                 if (deref_size == -1)
  1388.                   deref_size = ctx->addr_size;
  1389.                 op_ptr += len;
  1390.                 ctx->funcs->push_dwarf_reg_entry_value (ctx,
  1391.                                                   CALL_SITE_PARAMETER_DWARF_REG,
  1392.                                                         kind_u, deref_size);
  1393.                 goto no_push;
  1394.               }

  1396.             error (_("DWARF-2 expression error: DW_OP_GNU_entry_value is "
  1397.                      "supported only for single DW_OP_reg* "
  1398.                      "or for DW_OP_breg*(0)+DW_OP_deref*"));
  1399.           }

  1401.         case DW_OP_GNU_parameter_ref:
  1402.           {
  1403.             union call_site_parameter_u kind_u;

  1405.             kind_u.param_offset.cu_off = extract_unsigned_integer (op_ptr, 4,
  1406.                                                                    byte_order);
  1407.             op_ptr += 4;
  1408.             ctx->funcs->push_dwarf_reg_entry_value (ctx,
  1409.                                                CALL_SITE_PARAMETER_PARAM_OFFSET,
  1410.                                                     kind_u,
  1411.                                                     -1 /* deref_size */);
  1412.           }
  1413.           goto no_push;

  1415.         case DW_OP_GNU_const_type:
  1416.           {
  1417.             cu_offset type_die;
  1418.             int n;
  1419.             const gdb_byte *data;
  1420.             struct type *type;

  1422.             op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
  1423.             type_die.cu_off = uoffset;
  1424.             n = *op_ptr++;
  1425.             data = op_ptr;
  1426.             op_ptr += n;

  1428.             type = dwarf_get_base_type (ctx, type_die, n);
  1429.             result_val = value_from_contents (type, data);
  1430.           }
  1431.           break;

  1433.         case DW_OP_GNU_regval_type:
  1434.           {
  1435.             cu_offset type_die;
  1436.             struct type *type;

  1438.             op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
  1439.             op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
  1440.             type_die.cu_off = uoffset;

  1442.             type = dwarf_get_base_type (ctx, type_die, 0);
  1443.             result_val = ctx->funcs->get_reg_value (ctx->baton, type, reg);
  1444.           }
  1445.           break;

  1447.         case DW_OP_GNU_convert:
  1448.         case DW_OP_GNU_reinterpret:
  1449.           {
  1450.             cu_offset type_die;
  1451.             struct type *type;

  1453.             op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
  1454.             type_die.cu_off = uoffset;

  1456.             if (type_die.cu_off == 0)
  1457.               type = address_type;
  1458.             else
  1459.               type = dwarf_get_base_type (ctx, type_die, 0);

  1461.             result_val = dwarf_expr_fetch (ctx, 0);
  1462.             dwarf_expr_pop (ctx);

  1464.             if (op == DW_OP_GNU_convert)
  1465.               result_val = value_cast (type, result_val);
  1466.             else if (type == value_type (result_val))
  1467.               {
  1468.                 /* Nothing.  */
  1469.               }
  1470.             else if (TYPE_LENGTH (type)
  1471.                      != TYPE_LENGTH (value_type (result_val)))
  1472.               error (_("DW_OP_GNU_reinterpret has wrong size"));
  1473.             else
  1474.               result_val
  1475.                 = value_from_contents (type,
  1476.                                        value_contents_all (result_val));
  1477.           }
  1478.           break;

  1480.         case DW_OP_push_object_address:
  1481.           /* Return the address of the object we are currently observing.  */
  1482.           result = (ctx->funcs->get_object_address) (ctx->baton);
  1483.           result_val = value_from_ulongest (address_type, result);
  1484.           break;

  1486.         default:
  1487.           error (_("Unhandled dwarf expression opcode 0x%x"), op);
  1488.         }

  1490.       /* Most things push a result value.  */
  1491.       gdb_assert (result_val != NULL);
  1492.       dwarf_expr_push (ctx, result_val, in_stack_memory);
  1493.     no_push:
  1494.       ;
  1495.     }

  1497.   /* To simplify our main caller, if the result is an implicit
  1498.      pointer, then make a pieced value.  This is ok because we can't
  1499.      have implicit pointers in contexts where pieces are invalid.  */
  1500.   if (ctx->location == DWARF_VALUE_IMPLICIT_POINTER)
  1501.     add_piece (ctx, 8 * ctx->addr_size, 0);

  1503. abort_expression:
  1504.   ctx->recursion_depth--;
  1505.   gdb_assert (ctx->recursion_depth >= 0);
  1506. }

  1508. /* Stub dwarf_expr_context_funcs.get_frame_base implementation.  */

  1510. void
  1511. ‌ctx_no_get_frame_base (void *baton, const gdb_byte **start, size_t *length)
  1512. {
  1513.   error (_("%s is invalid in this context"), "DW_OP_fbreg");
  1514. }

  1516. /* Stub dwarf_expr_context_funcs.get_frame_cfa implementation.  */

  1518. CORE_ADDR
  1519. ‌ctx_no_get_frame_cfa (void *baton)
  1520. {
  1521.   error (_("%s is invalid in this context"), "DW_OP_call_frame_cfa");
  1522. }

  1524. /* Stub dwarf_expr_context_funcs.get_frame_pc implementation.  */

  1526. CORE_ADDR
  1527. ‌ctx_no_get_frame_pc (void *baton)
  1528. {
  1529.   error (_("%s is invalid in this context"), "DW_OP_GNU_implicit_pointer");
  1530. }

  1532. /* Stub dwarf_expr_context_funcs.get_tls_address implementation.  */

  1534. CORE_ADDR
  1535. ‌ctx_no_get_tls_address (void *baton, CORE_ADDR offset)
  1536. {
  1537.   error (_("%s is invalid in this context"), "DW_OP_GNU_push_tls_address");
  1538. }

  1540. /* Stub dwarf_expr_context_funcs.dwarf_call implementation.  */

  1542. void
  1543. ‌ctx_no_dwarf_call (struct dwarf_expr_context *ctx, cu_offset die_offset)
  1544. {
  1545.   error (_("%s is invalid in this context"), "DW_OP_call*");
  1546. }

  1548. /* Stub dwarf_expr_context_funcs.get_base_type implementation.  */

  1550. struct type *
  1551. ‌ctx_no_get_base_type (struct dwarf_expr_context *ctx, cu_offset die)
  1552. {
  1553.   error (_("Support for typed DWARF is not supported in this context"));
  1554. }

  1556. /* Stub dwarf_expr_context_funcs.push_dwarf_block_entry_value
  1557.    implementation.  */

  1559. void
  1560. ‌ctx_no_push_dwarf_reg_entry_value (struct dwarf_expr_context *ctx,
  1561.                                    enum call_site_parameter_kind kind,
  1562.                                    union call_site_parameter_u kind_u,
  1563.                                    int deref_size)
  1564. {
  1565.   internal_error (__FILE__, __LINE__,
  1566.                   _("Support for DW_OP_GNU_entry_value is unimplemented"));
  1567. }

  1569. /* Stub dwarf_expr_context_funcs.get_addr_index implementation.  */

  1571. CORE_ADDR
  1572. ‌ctx_no_get_addr_index (void *baton, unsigned int index)
  1573. {
  1574.   error (_("%s is invalid in this context"), "DW_OP_GNU_addr_index");
  1575. }

  1577. /* Provide a prototype to silence -Wmissing-prototypes.  */
  1578. extern initialize_file_ftype _initialize_dwarf2expr;

  1580. void
  1581. ‌_initialize_dwarf2expr (void)
  1582. {
  1583.   dwarf_arch_cookie
  1584.     = gdbarch_data_register_post_init (dwarf_gdbarch_types_init);
  1585. }