except.c (func_eh_entry): Add emitted field.

2000-05-25  Andrew MacLeod  <amacleod@cygnus.com>
            Andrew Haley  <aph@cygnus.com>

	* except.c  (func_eh_entry): Add emitted field.
	(new_eh_region_entry): Set emitted field to 0;
	(output_exception_table_entry): Only emit previously un-emitted data,
	and send it to the eh_data section.
	(output_exception_table): Break out common parts. Output
	exception table for entire compilation unit to eh_data section.
	(output_exception_table_data): Common parts of output_exception_table.
	Send output to eh_data section.
	(output_function_exception_table): Output exception table data for
	a single function to eh_data section.
	(free_exception_table): New external to free the table.
	* except.h (free_exception_table): Add prototype.
	(output_function_exception_table): Add prototype.
	* final.c (final_end_function): Output function exception table
	for IA64_UNWIND_INFO.
	(final_scan_insn): Emit any unwind directives for an insn.

	* frame-dwarf2.c: New file containing all DWARF 2 specific code
	from frame.c.
	* frame.c: Remove all DWARF 2 specific code.
	* config/ia64/frame-ia64.c: New file.
	(gthread_stuff): Make all gthread available with
	IA64_UNWIND_INFO.
	(dwarf_fde): Define an IA64 struct for dwarf_fde.
	(__register_frame_info, __register_frame): Move to common area of file.
	(__register_frame_info_table, __register_frame_table): Move to common i
	area.
	(__deregister_frame_info, __deregister_frame): Move to common area.
	(__frame_init, find_fde): New versions for IA64_UNWIND_INFO.
	(read_uleb128): New version for ia64.
	(get_unwind_record): Read the next IA-64 unwind record.
	(read_R_record): Read a region header record.
	(process_a_b_reg_code): X record helper.
	(read_X_record): Read an X format record.
	(read_B_record): Read a B format record.
	(P3_record_types): List of record types matching the P3 format.
	(P7_record_types): List of record types matching the P7 format.
	(P8_record_types): List of record types matching the P8 format.
	(read_P_record): Read a P format record.
	(init_ia64_reg_loc): Set default fields for a register.
	(init_ia64_unwind_frame): Set defaults for all register records.
	(execute_one_ia64_descriptor): Execute one descriptor record.
	(rse_address_add): Calculate the position of a local reg in memory.
	(normalize_reg_loc): Turn a location descriptor into a memory address.
	(maybe_normalize_reg_loc): Only normalize a descriptor if it falls
	within a specified PC offset range.
	(get_real_reg_value): Given a register location, retrieve its value.
	(set_real_reg_value): Change the value of a register location.
	(copy_reg_value): Copy reg values, if needed.
	(copy_saved_reg_state): Copy all registers that need to be copied.
	(process_state_between): Normalize all frame register records that
	fall within the specified PC range.
	(frame_translate): Take a processed frame description, and turn
	everything into addresses.
	(build_ia64_frame_state ): Find and create frame state record for a PC.
	(get_personality): Get the personality routine for a given frame.
	(get_except_table): Get the exception table for a given frame.
	(record_name): Unwind record names for debugging.
	(print_record): Print and unwind record.
	(print_all_records): Print an entire unwind image.
	(__ia64_backtrace): Print a backtrace.
	(ia64_backtrace_helper): New function.
	(__register_frame_info_aux): New function.
	* config/ia64/crtend.asm (__do_frame_setup_aux): New function.

	* frame.h (enum unw_record_type): New unwind record types.
	(struct unw_p_record, unw_b_record, unw_x_record) : New unwind records.
	(struct unw_r_record, unwind_record): New unwind record structs.
	(struct unwind_info_ptr): Unwind information layout.
	(IA64_UNW_LOC_TYPE_*): Macros for different types for location
	descriptors.
	(struct ia64_reg_loc): Register location description.
	(struct ia64_frame_state): Location of all registers in a frame.
	(struct object): Add pc_base and fde_end for IA64_UNWIND_INFO.
	* libgcc2.c (__ia64_personality_v1): Personality routine.
	(__calc_caller_bsp): Calculate the bsp register for the caller's
	frame.
	(ia64_throw_helper): Figure out who to return to and set up the
	registers.
	(__throw): Throw routine.

	* output.h (assemble_eh_align, assemble_eh_label): New functions
	to generate EH info where we want it.
	(assemble_eh_integer): New function.
	* toplev.c (compile_file): Output module level exception table for
	non-ia64 targets.
	(main): Set exceptions_via_longjump and flag_new_exceptions based
	on IA64_UNWIND_INFO too.

	* varasm.c (assemble_eh_label): Generate a label via
	ASM_OUTPUT_EH_LABEL if it has been specified.
	(assemble_eh_align): Generate an alignment directive via
	ASM_OUTPUT_EH_ALIGN if it has been specified.
	(assemble_eh_label): Generate an integer value via
	ASM_OUTPUT_EH_type if they have been specified.
	* config/ia64/ia64.c (rtx_needs_barrier): Add flushrs.
	(ia64_init_builtins): Add __builtin_ia64_bsp
	and __builtin_ia64_flushrs.
	(ia64_expand_builtin): Add IA64_BUILTIN_BSP and
	IA64_BUILTIN_FLUSHRS.
	* config/ia64/ia64.h (ia64_builtins): Add IA64_BUILTIN_BSP and
	IA64_BUILTIN_FLUSHRS.

	* config/ia64/ia64.md (flushrs): New insn to flush the register
	stack.  Add to unspec list.

	* config/ia64/crtbegin.asm (frame_object): Change size.
	(__do_frame_setup_aux): New function.
	* config/ia64/crtend.asm: call __do_frame_setup_aux.
	* config/ia64/t-ia64 (LIB2ADDEH): Add.
	* Makefile.in (LIB2ADDEH): Add.
	(LIB2ADD): Use LIB2ADDEH.

Co-Authored-By: Andrew Haley <aph@cygnus.com>

From-SVN: r34169

1 files changed, 663 insertions, 0 deletions

diff --git a/gcc/frame-dwarf2.c b/gcc/frame-dwarf2.c
new file mode 100644
index 0000000..fb2e9fb
--- /dev/null
+++ b/gcc/frame-dwarf2.c
@@ -0,0 +1,663 @@
+/* Subroutines needed for unwinding DWARF 2 format stack frame info
+   for exception handling.  */
+/* Compile this one with gcc.  */
+/* Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
+   Contributed by Jason Merrill <jason@cygnus.com>.
+
+This file is part of GNU CC.
+
+GNU CC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+In addition to the permissions in the GNU General Public License, the
+Free Software Foundation gives you unlimited permission to link the
+compiled version of this file into combinations with other programs,
+and to distribute those combinations without any restriction coming
+from the use of this file.  (The General Public License restrictions
+do apply in other respects; for example, they cover modification of
+the file, and distribution when not linked into a combine
+executable.)
+
+GNU CC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU CC; see the file COPYING.  If not, write to
+the Free Software Foundation, 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+/* It is incorrect to include config.h here, because this file is being
+   compiled for the target, and hence definitions concerning only the host
+   do not apply.  */
+
+#include "tconfig.h"
+#include "tsystem.h"
+
+#include "defaults.h"
+
+#ifdef DWARF2_UNWIND_INFO
+#include "dwarf2.h"
+#include "frame.h"
+#include "gthr.h"
+
+#ifdef __GTHREAD_MUTEX_INIT
+static __gthread_mutex_t object_mutex = __GTHREAD_MUTEX_INIT;
+#else
+static __gthread_mutex_t object_mutex;
+#endif
+
+/* Don't use `fancy_abort' here even if config.h says to use it.  */
+#ifdef abort
+#undef abort
+#endif
+
+/* Some types used by the DWARF 2 spec.  */
+
+typedef          int  sword __attribute__ ((mode (SI)));
+typedef unsigned int  uword __attribute__ ((mode (SI)));
+typedef unsigned int  uaddr __attribute__ ((mode (pointer)));
+typedef          int  saddr __attribute__ ((mode (pointer)));
+typedef unsigned char ubyte;
+
+/* Terminology:
+   CIE - Common Information Element
+   FDE - Frame Descriptor Element
+
+   There is one per function, and it describes where the function code
+   is located, and what the register lifetimes and stack layout are
+   within the function.
+
+   The data structures are defined in the DWARF specfication, although
+   not in a very readable way (see LITERATURE).
+
+   Every time an exception is thrown, the code needs to locate the FDE
+   for the current function, and starts to look for exception regions
+   from that FDE. This works in a two-level search:
+   a) in a linear search, find the shared image (i.e. DLL) containing
+      the PC
+   b) using the FDE table for that shared object, locate the FDE using
+      binary search (which requires the sorting).  */   
+
+/* The first few fields of a CIE.  The CIE_id field is 0 for a CIE,
+   to distinguish it from a valid FDE.  FDEs are aligned to an addressing
+   unit boundary, but the fields within are unaligned.  */
+
+struct dwarf_cie {
+  uword length;
+  sword CIE_id;
+  ubyte version;
+  char augmentation[0];
+} __attribute__ ((packed, aligned (__alignof__ (void *))));
+
+/* The first few fields of an FDE.  */
+
+struct dwarf_fde {
+  uword length;
+  sword CIE_delta;
+  void* pc_begin;
+  uaddr pc_range;
+} __attribute__ ((packed, aligned (__alignof__ (void *))));
+
+typedef struct dwarf_fde fde;
+
+/* Objects to be searched for frame unwind info.  */
+
+static struct object *objects;
+
+/* The information we care about from a CIE.  */
+
+struct cie_info {
+  char *augmentation;
+  void *eh_ptr;
+  int code_align;
+  int data_align;
+  unsigned ra_regno;
+};
+
+/* The current unwind state, plus a saved copy for DW_CFA_remember_state.  */
+
+struct frame_state_internal
+{
+  struct frame_state s;
+  struct frame_state_internal *saved_state;
+};
+
+/* This is undefined below if we need it to be an actual function.  */
+#define init_object_mutex_once()
+
+#if __GTHREADS
+#ifdef __GTHREAD_MUTEX_INIT_FUNCTION
+
+/* Helper for init_object_mutex_once.  */
+
+static void
+init_object_mutex (void)
+{
+  __GTHREAD_MUTEX_INIT_FUNCTION (&object_mutex);
+}
+
+/* Call this to arrange to initialize the object mutex.  */
+
+#undef init_object_mutex_once
+static void
+init_object_mutex_once (void)
+{
+  static __gthread_once_t once = __GTHREAD_ONCE_INIT;
+  __gthread_once (&once, init_object_mutex);
+}
+
+#endif /* __GTHREAD_MUTEX_INIT_FUNCTION */
+#endif /* __GTHREADS */
+  
+/* Decode the unsigned LEB128 constant at BUF into the variable pointed to
+   by R, and return the new value of BUF.  */
+
+static void *
+decode_uleb128 (unsigned char *buf, unsigned *r)
+{
+  unsigned shift = 0;
+  unsigned result = 0;
+
+  while (1)
+    {
+      unsigned byte = *buf++;
+      result |= (byte & 0x7f) << shift;
+      if ((byte & 0x80) == 0)
+	break;
+      shift += 7;
+    }
+  *r = result;
+  return buf;
+}
+
+/* Decode the signed LEB128 constant at BUF into the variable pointed to
+   by R, and return the new value of BUF.  */
+
+static void *
+decode_sleb128 (unsigned char *buf, int *r)
+{
+  unsigned shift = 0;
+  unsigned result = 0;
+  unsigned byte;
+
+  while (1)
+    {
+      byte = *buf++;
+      result |= (byte & 0x7f) << shift;
+      shift += 7;
+      if ((byte & 0x80) == 0)
+	break;
+    }
+  if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0)
+    result |= - (1 << shift);
+
+  *r = result;
+  return buf;
+}
+
+/* Read unaligned data from the instruction buffer.  */
+
+union unaligned {
+  void *p;
+  unsigned b2 __attribute__ ((mode (HI)));
+  unsigned b4 __attribute__ ((mode (SI)));
+  unsigned b8 __attribute__ ((mode (DI)));
+} __attribute__ ((packed));
+static inline void *
+read_pointer (void *p)
+{ union unaligned *up = p; return up->p; }
+static inline unsigned
+read_1byte (void *p)
+{ return *(unsigned char *)p; }
+static inline unsigned
+read_2byte (void *p)
+{ union unaligned *up = p; return up->b2; }
+static inline unsigned
+read_4byte (void *p)
+{ union unaligned *up = p; return up->b4; }
+static inline unsigned long
+read_8byte (void *p)
+{ union unaligned *up = p; return up->b8; }
+
+/* Ordering function for FDEs.  Functions can't overlap, so we just compare
+   their starting addresses.  */
+
+static inline saddr
+fde_compare (fde *x, fde *y)
+{
+  return (saddr)x->pc_begin - (saddr)y->pc_begin;
+}
+
+/* Return the address of the FDE after P.  */
+
+static inline fde *
+next_fde (fde *p)
+{
+  return (fde *)(((char *)p) + p->length + sizeof (p->length));
+}
+
+#include "frame.c"
+
+static size_t
+count_fdes (fde *this_fde)
+{
+  size_t count;
+
+  for (count = 0; this_fde->length != 0; this_fde = next_fde (this_fde))
+    {
+      /* Skip CIEs and linked once FDE entries.  */
+      if (this_fde->CIE_delta == 0 || this_fde->pc_begin == 0)
+	continue;
+
+      ++count;
+    }
+
+  return count;
+}
+
+static void
+add_fdes (fde *this_fde, fde_accumulator *accu, void **beg_ptr, void **end_ptr)
+{
+  void *pc_begin = *beg_ptr;
+  void *pc_end = *end_ptr;
+
+  for (; this_fde->length != 0; this_fde = next_fde (this_fde))
+    {
+      /* Skip CIEs and linked once FDE entries.  */
+      if (this_fde->CIE_delta == 0 || this_fde->pc_begin == 0)
+	continue;
+
+      fde_insert (accu, this_fde);
+
+      if (this_fde->pc_begin < pc_begin)
+	pc_begin = this_fde->pc_begin;
+      if (this_fde->pc_begin + this_fde->pc_range > pc_end)
+	pc_end = this_fde->pc_begin + this_fde->pc_range;
+    }
+
+  *beg_ptr = pc_begin;
+  *end_ptr = pc_end;
+}
+
+/* search this fde table for the one containing the pc */
+static fde *
+search_fdes (fde *this_fde, void *pc)
+{
+  for (; this_fde->length != 0; this_fde = next_fde (this_fde))
+    {
+      /* Skip CIEs and linked once FDE entries.  */
+      if (this_fde->CIE_delta == 0 || this_fde->pc_begin == 0)
+	continue;
+
+      if ((uaddr)((char *)pc - (char *)this_fde->pc_begin) < this_fde->pc_range)
+	return this_fde;
+    }
+  return NULL;
+}
+
+/* Set up a sorted array of pointers to FDEs for a loaded object.  We
+   count up the entries before allocating the array because it's likely to
+   be faster.  We can be called multiple times, should we have failed to
+   allocate a sorted fde array on a previous occasion.  */
+
+static void
+frame_init (struct object* ob)
+{
+  size_t count;
+  fde_accumulator accu;
+  void *pc_begin, *pc_end;
+  fde **array;
+
+  if (ob->pc_begin)
+    count = ob->count;
+  else if (ob->fde_array)
+    {
+      fde **p = ob->fde_array;
+      for (count = 0; *p; ++p)
+	count += count_fdes (*p);
+    }
+  else
+    count = count_fdes (ob->fde_begin);
+  ob->count = count;
+
+  if (!start_fde_sort (&accu, count) && ob->pc_begin)
+    return;
+
+  pc_begin = (void*)(uaddr)-1;
+  pc_end = 0;
+
+  if (ob->fde_array)
+    {
+      fde **p = ob->fde_array;
+      for (; *p; ++p)
+	add_fdes (*p, &accu, &pc_begin, &pc_end);
+    }
+  else
+    add_fdes (ob->fde_begin, &accu, &pc_begin, &pc_end);
+
+  array = end_fde_sort (&accu, count);
+  if (array)
+    ob->fde_array = array;
+  ob->pc_begin = pc_begin;
+  ob->pc_end = pc_end;
+}
+
+/* Return a pointer to the FDE for the function containing PC.  */
+
+static fde *
+find_fde (void *pc)
+{
+  struct object *ob;
+  size_t lo, hi;
+
+  init_object_mutex_once ();
+  __gthread_mutex_lock (&object_mutex);
+
+  /* Linear search through the objects, to find the one containing the pc. */
+  for (ob = objects; ob; ob = ob->next)
+    {
+      if (ob->pc_begin == 0)
+	frame_init (ob);
+      if (pc >= ob->pc_begin && pc < ob->pc_end)
+	break;
+    }
+
+  if (ob == 0)
+    {
+      __gthread_mutex_unlock (&object_mutex);
+      return 0;
+    }
+
+  if (!ob->fde_array || (void *)ob->fde_array == (void *)ob->fde_begin)
+    frame_init (ob);
+
+  if (ob->fde_array && (void *)ob->fde_array != (void *)ob->fde_begin)
+    {
+      __gthread_mutex_unlock (&object_mutex);
+      
+      /* Standard binary search algorithm.  */
+      for (lo = 0, hi = ob->count; lo < hi; )
+	{
+	  size_t i = (lo + hi) / 2;
+	  fde *f = ob->fde_array[i];
+
+	  if (pc < f->pc_begin)
+	    hi = i;
+	  else if (pc >= f->pc_begin + f->pc_range)
+	    lo = i + 1;
+	  else
+	    return f;
+	}
+    }
+  else
+    {
+      /* Long slow labourious linear search, cos we've no memory. */
+      fde *f;
+      
+      if (ob->fde_array)
+	{
+	  fde **p = ob->fde_array;
+	  
+	  do
+	    {
+	      f = search_fdes (*p, pc);
+	      if (f)
+		break;
+	      p++;
+	    }
+	  while (*p);
+	}
+      else
+	f = search_fdes (ob->fde_begin, pc);
+      __gthread_mutex_unlock (&object_mutex);
+      return f;
+    }
+  return 0;
+}
+
+static inline struct dwarf_cie *
+get_cie (fde *f)
+{
+  return ((void *)&f->CIE_delta) - f->CIE_delta;
+}
+
+/* Extract any interesting information from the CIE for the translation
+   unit F belongs to.  */
+
+static void *
+extract_cie_info (fde *f, struct cie_info *c)
+{
+  void *p;
+  int i;
+
+  c->augmentation = get_cie (f)->augmentation;
+
+  if (strcmp (c->augmentation, "") != 0
+      && strcmp (c->augmentation, "eh") != 0
+      && c->augmentation[0] != 'z')
+    return 0;
+
+  p = c->augmentation + strlen (c->augmentation) + 1;
+
+  if (strcmp (c->augmentation, "eh") == 0)
+    {
+      c->eh_ptr = read_pointer (p);
+      p += sizeof (void *);
+    }
+  else
+    c->eh_ptr = 0;
+
+  p = decode_uleb128 (p, &c->code_align);
+  p = decode_sleb128 (p, &c->data_align);
+  c->ra_regno = *(unsigned char *)p++;
+
+  /* If the augmentation starts with 'z', we now see the length of the
+     augmentation fields.  */
+  if (c->augmentation[0] == 'z')
+    {
+      p = decode_uleb128 (p, &i);
+      p += i;
+    }
+
+  return p;
+}
+
+/* Decode one instruction's worth of DWARF 2 call frame information.
+   Used by __frame_state_for.  Takes pointers P to the instruction to
+   decode, STATE to the current register unwind information, INFO to the
+   current CIE information, and PC to the current PC value.  Returns a
+   pointer to the next instruction.  */
+
+static void *
+execute_cfa_insn (void *p, struct frame_state_internal *state,
+		  struct cie_info *info, void **pc)
+{
+  unsigned insn = *(unsigned char *)p++;
+  unsigned reg;
+  int offset;
+
+  if (insn & DW_CFA_advance_loc)
+    *pc += ((insn & 0x3f) * info->code_align);
+  else if (insn & DW_CFA_offset)
+    {
+      reg = (insn & 0x3f);
+      p = decode_uleb128 (p, &offset);
+      if (reg == state->s.cfa_reg)
+	/* Don't record anything about this register; it's only used to
+	   reload SP in the epilogue.  We don't want to copy in SP
+	   values for outer frames; we handle restoring SP specially.  */;
+      else
+	{
+	  offset *= info->data_align;
+	  state->s.saved[reg] = REG_SAVED_OFFSET;
+	  state->s.reg_or_offset[reg] = offset;
+	}
+    }
+  else if (insn & DW_CFA_restore)
+    {
+      reg = (insn & 0x3f);
+      state->s.saved[reg] = REG_UNSAVED;
+    }
+  else switch (insn)
+    {
+    case DW_CFA_set_loc:
+      *pc = read_pointer (p);
+      p += sizeof (void *);
+      break;
+    case DW_CFA_advance_loc1:
+      *pc += read_1byte (p);
+      p += 1;
+      break;
+    case DW_CFA_advance_loc2:
+      *pc += read_2byte (p);
+      p += 2;
+      break;
+    case DW_CFA_advance_loc4:
+      *pc += read_4byte (p);
+      p += 4;
+      break;
+
+    case DW_CFA_offset_extended:
+      p = decode_uleb128 (p, &reg);
+      p = decode_uleb128 (p, &offset);
+      if (reg == state->s.cfa_reg)
+	/* Don't record anything; see above.  */;
+      else
+	{
+	  offset *= info->data_align;
+	  state->s.saved[reg] = REG_SAVED_OFFSET;
+	  state->s.reg_or_offset[reg] = offset;
+	}
+      break;
+    case DW_CFA_restore_extended:
+      p = decode_uleb128 (p, &reg);
+      state->s.saved[reg] = REG_UNSAVED;
+      break;
+
+    case DW_CFA_undefined:
+    case DW_CFA_same_value:
+    case DW_CFA_nop:
+      break;
+
+    case DW_CFA_register:
+      {
+	unsigned reg2;
+	p = decode_uleb128 (p, &reg);
+	p = decode_uleb128 (p, &reg2);
+	state->s.saved[reg] = REG_SAVED_REG;
+	state->s.reg_or_offset[reg] = reg2;
+      }
+      break;
+
+    case DW_CFA_def_cfa:
+      p = decode_uleb128 (p, &reg);
+      p = decode_uleb128 (p, &offset);
+      state->s.cfa_reg = reg;
+      state->s.cfa_offset = offset;
+      break;
+    case DW_CFA_def_cfa_register:
+      p = decode_uleb128 (p, &reg);
+      state->s.cfa_reg = reg;
+      break;
+    case DW_CFA_def_cfa_offset:
+      p = decode_uleb128 (p, &offset);
+      state->s.cfa_offset = offset;
+      break;
+      
+    case DW_CFA_remember_state:
+      {
+	struct frame_state_internal *save =
+	  (struct frame_state_internal *)
+	  malloc (sizeof (struct frame_state_internal));
+	memcpy (save, state, sizeof (struct frame_state_internal));
+	state->saved_state = save;
+      }
+      break;
+    case DW_CFA_restore_state:
+      {
+	struct frame_state_internal *save = state->saved_state;
+	memcpy (state, save, sizeof (struct frame_state_internal));
+	free (save);
+      }
+      break;
+
+      /* FIXME: Hardcoded for SPARC register window configuration.  */
+    case DW_CFA_GNU_window_save:
+      for (reg = 16; reg < 32; ++reg)
+	{
+	  state->s.saved[reg] = REG_SAVED_OFFSET;
+	  state->s.reg_or_offset[reg] = (reg - 16) * sizeof (void *);
+	}
+      break;
+
+    case DW_CFA_GNU_args_size:
+      p = decode_uleb128 (p, &offset);
+      state->s.args_size = offset;
+      break;
+
+    case DW_CFA_GNU_negative_offset_extended:
+      p = decode_uleb128 (p, &reg);
+      p = decode_uleb128 (p, &offset);
+      offset *= info->data_align;
+      state->s.saved[reg] = REG_SAVED_OFFSET;
+      state->s.reg_or_offset[reg] = -offset;
+      break;
+
+    default:
+      abort ();
+    }
+  return p;
+}
+
+/* Called from __throw to find the registers to restore for a given
+   PC_TARGET.  The caller should allocate a local variable of `struct
+   frame_state' (declared in frame.h) and pass its address to STATE_IN.  */
+
+struct frame_state *
+__frame_state_for (void *pc_target, struct frame_state *state_in)
+{
+  fde *f;
+  void *insn, *end, *pc;
+  struct cie_info info;
+  struct frame_state_internal state;
+
+  f = find_fde (pc_target);
+  if (f == 0)
+    return 0;
+
+  insn = extract_cie_info (f, &info);
+  if (insn == 0)
+    return 0;
+
+  memset (&state, 0, sizeof (state));
+  state.s.retaddr_column = info.ra_regno;
+  state.s.eh_ptr = info.eh_ptr;
+
+  /* First decode all the insns in the CIE.  */
+  end = next_fde ((fde*) get_cie (f));
+  while (insn < end)
+    insn = execute_cfa_insn (insn, &state, &info, 0);
+
+  insn = ((fde *)f) + 1;
+
+  if (info.augmentation[0] == 'z')
+    {
+      int i;
+      insn = decode_uleb128 (insn, &i);
+      insn += i;
+    }
+
+  /* Then the insns in the FDE up to our target PC.  */
+  end = next_fde (f);
+  pc = f->pc_begin;
+  while (insn < end && pc <= pc_target)
+    insn = execute_cfa_insn (insn, &state, &info, &pc);
+
+  memcpy (state_in, &state.s, sizeof (state.s));
+  return state_in;
+}
+#endif /* DWARF2_UNWIND_INFO */