GDB 6.1 (excluding .info files)

1 files changed, 1613 insertions, 0 deletions

diff --git a/gnu/usr.bin/binutils/gdb/dwarf2-frame.c b/gnu/usr.bin/binutils/gdb/dwarf2-frame.c
new file mode 100644
index 00000000000..8c624198453
--- /dev/null
+++ b/gnu/usr.bin/binutils/gdb/dwarf2-frame.c
@@ -0,0 +1,1613 @@
+/* Frame unwinder for frames with DWARF Call Frame Information.
+
+   Copyright 2003, 2004 Free Software Foundation, Inc.
+
+   Contributed by Mark Kettenis.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include "defs.h"
+#include "dwarf2expr.h"
+#include "elf/dwarf2.h"
+#include "frame.h"
+#include "frame-base.h"
+#include "frame-unwind.h"
+#include "gdbcore.h"
+#include "gdbtypes.h"
+#include "symtab.h"
+#include "objfiles.h"
+#include "regcache.h"
+
+#include "gdb_assert.h"
+#include "gdb_string.h"
+
+#include "complaints.h"
+#include "dwarf2-frame.h"
+
+/* Call Frame Information (CFI).  */
+
+/* Common Information Entry (CIE).  */
+
+struct dwarf2_cie
+{
+  /* Offset into the .debug_frame section where this CIE was found.
+     Used to identify this CIE.  */
+  ULONGEST cie_pointer;
+
+  /* Constant that is factored out of all advance location
+     instructions.  */
+  ULONGEST code_alignment_factor;
+
+  /* Constants that is factored out of all offset instructions.  */
+  LONGEST data_alignment_factor;
+
+  /* Return address column.  */
+  ULONGEST return_address_register;
+
+  /* Instruction sequence to initialize a register set.  */
+  unsigned char *initial_instructions;
+  unsigned char *end;
+
+  /* Encoding of addresses.  */
+  unsigned char encoding;
+
+  /* True if a 'z' augmentation existed.  */
+  unsigned char saw_z_augmentation;
+
+  struct dwarf2_cie *next;
+};
+
+/* Frame Description Entry (FDE).  */
+
+struct dwarf2_fde
+{
+  /* CIE for this FDE.  */
+  struct dwarf2_cie *cie;
+
+  /* First location associated with this FDE.  */
+  CORE_ADDR initial_location;
+
+  /* Number of bytes of program instructions described by this FDE.  */
+  CORE_ADDR address_range;
+
+  /* Instruction sequence.  */
+  unsigned char *instructions;
+  unsigned char *end;
+
+  struct dwarf2_fde *next;
+};
+
+static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc);
+
+
+/* Structure describing a frame state.  */
+
+struct dwarf2_frame_state
+{
+  /* Each register save state can be described in terms of a CFA slot,
+     another register, or a location expression.  */
+  struct dwarf2_frame_state_reg_info
+  {
+    struct dwarf2_frame_state_reg *reg;
+    int num_regs;
+
+    /* Used to implement DW_CFA_remember_state.  */
+    struct dwarf2_frame_state_reg_info *prev;
+  } regs;
+
+  LONGEST cfa_offset;
+  ULONGEST cfa_reg;
+  unsigned char *cfa_exp;
+  enum {
+    CFA_UNSET,
+    CFA_REG_OFFSET,
+    CFA_EXP
+  } cfa_how;
+
+  /* The PC described by the current frame state.  */
+  CORE_ADDR pc;
+
+  /* Initial register set from the CIE.
+     Used to implement DW_CFA_restore.  */
+  struct dwarf2_frame_state_reg_info initial;
+
+  /* The information we care about from the CIE.  */
+  LONGEST data_align;
+  ULONGEST code_align;
+  ULONGEST retaddr_column;
+};
+
+/* Store the length the expression for the CFA in the `cfa_reg' field,
+   which is unused in that case.  */
+#define cfa_exp_len cfa_reg
+
+/* Assert that the register set RS is large enough to store NUM_REGS
+   columns.  If necessary, enlarge the register set.  */
+
+static void
+dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs,
+			       int num_regs)
+{
+  size_t size = sizeof (struct dwarf2_frame_state_reg);
+
+  if (num_regs <= rs->num_regs)
+    return;
+
+  rs->reg = (struct dwarf2_frame_state_reg *)
+    xrealloc (rs->reg, num_regs * size);
+
+  /* Initialize newly allocated registers.  */
+  memset (rs->reg + rs->num_regs, 0, (num_regs - rs->num_regs) * size);
+  rs->num_regs = num_regs;
+}
+
+/* Copy the register columns in register set RS into newly allocated
+   memory and return a pointer to this newly created copy.  */
+
+static struct dwarf2_frame_state_reg *
+dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info *rs)
+{
+  size_t size = rs->num_regs * sizeof (struct dwarf2_frame_state_reg_info);
+  struct dwarf2_frame_state_reg *reg;
+
+  reg = (struct dwarf2_frame_state_reg *) xmalloc (size);
+  memcpy (reg, rs->reg, size);
+
+  return reg;
+}
+
+/* Release the memory allocated to register set RS.  */
+
+static void
+dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info *rs)
+{
+  if (rs)
+    {
+      dwarf2_frame_state_free_regs (rs->prev);
+
+      xfree (rs->reg);
+      xfree (rs);
+    }
+}
+
+/* Release the memory allocated to the frame state FS.  */
+
+static void
+dwarf2_frame_state_free (void *p)
+{
+  struct dwarf2_frame_state *fs = p;
+
+  dwarf2_frame_state_free_regs (fs->initial.prev);
+  dwarf2_frame_state_free_regs (fs->regs.prev);
+  xfree (fs->initial.reg);
+  xfree (fs->regs.reg);
+  xfree (fs);
+}
+
+
+/* Helper functions for execute_stack_op.  */
+
+static CORE_ADDR
+read_reg (void *baton, int reg)
+{
+  struct frame_info *next_frame = (struct frame_info *) baton;
+  struct gdbarch *gdbarch = get_frame_arch (next_frame);
+  int regnum;
+  char *buf;
+
+  regnum = DWARF2_REG_TO_REGNUM (reg);
+
+  buf = (char *) alloca (register_size (gdbarch, regnum));
+  frame_unwind_register (next_frame, regnum, buf);
+  return extract_typed_address (buf, builtin_type_void_data_ptr);
+}
+
+static void
+read_mem (void *baton, char *buf, CORE_ADDR addr, size_t len)
+{
+  read_memory (addr, buf, len);
+}
+
+static void
+no_get_frame_base (void *baton, unsigned char **start, size_t *length)
+{
+  internal_error (__FILE__, __LINE__,
+		  "Support for DW_OP_fbreg is unimplemented");
+}
+
+static CORE_ADDR
+no_get_tls_address (void *baton, CORE_ADDR offset)
+{
+  internal_error (__FILE__, __LINE__,
+		  "Support for DW_OP_GNU_push_tls_address is unimplemented");
+}
+
+static CORE_ADDR
+execute_stack_op (unsigned char *exp, ULONGEST len,
+		  struct frame_info *next_frame, CORE_ADDR initial)
+{
+  struct dwarf_expr_context *ctx;
+  CORE_ADDR result;
+
+  ctx = new_dwarf_expr_context ();
+  ctx->baton = next_frame;
+  ctx->read_reg = read_reg;
+  ctx->read_mem = read_mem;
+  ctx->get_frame_base = no_get_frame_base;
+  ctx->get_tls_address = no_get_tls_address;
+
+  dwarf_expr_push (ctx, initial);
+  dwarf_expr_eval (ctx, exp, len);
+  result = dwarf_expr_fetch (ctx, 0);
+
+  if (ctx->in_reg)
+    result = read_reg (next_frame, result);
+
+  free_dwarf_expr_context (ctx);
+
+  return result;
+}
+
+
+static void
+execute_cfa_program (unsigned char *insn_ptr, unsigned char *insn_end,
+		     struct frame_info *next_frame,
+		     struct dwarf2_frame_state *fs)
+{
+  CORE_ADDR pc = frame_pc_unwind (next_frame);
+  int bytes_read;
+
+  while (insn_ptr < insn_end && fs->pc <= pc)
+    {
+      unsigned char insn = *insn_ptr++;
+      ULONGEST utmp, reg;
+      LONGEST offset;
+
+      if ((insn & 0xc0) == DW_CFA_advance_loc)
+	fs->pc += (insn & 0x3f) * fs->code_align;
+      else if ((insn & 0xc0) == DW_CFA_offset)
+	{
+	  reg = insn & 0x3f;
+	  insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
+	  offset = utmp * fs->data_align;
+	  dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	  fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
+	  fs->regs.reg[reg].loc.offset = offset;
+	}
+      else if ((insn & 0xc0) == DW_CFA_restore)
+	{
+	  gdb_assert (fs->initial.reg);
+	  reg = insn & 0x3f;
+	  dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	  fs->regs.reg[reg] = fs->initial.reg[reg];
+	}
+      else
+	{
+	  switch (insn)
+	    {
+	    case DW_CFA_set_loc:
+	      fs->pc = dwarf2_read_address (insn_ptr, insn_end, &bytes_read);
+	      insn_ptr += bytes_read;
+	      break;
+
+	    case DW_CFA_advance_loc1:
+	      utmp = extract_unsigned_integer (insn_ptr, 1);
+	      fs->pc += utmp * fs->code_align;
+	      insn_ptr++;
+	      break;
+	    case DW_CFA_advance_loc2:
+	      utmp = extract_unsigned_integer (insn_ptr, 2);
+	      fs->pc += utmp * fs->code_align;
+	      insn_ptr += 2;
+	      break;
+	    case DW_CFA_advance_loc4:
+	      utmp = extract_unsigned_integer (insn_ptr, 4);
+	      fs->pc += utmp * fs->code_align;
+	      insn_ptr += 4;
+	      break;
+
+	    case DW_CFA_offset_extended:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
+	      offset = utmp * fs->data_align;
+	      dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	      fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
+	      fs->regs.reg[reg].loc.offset = offset;
+	      break;
+
+	    case DW_CFA_restore_extended:
+	      gdb_assert (fs->initial.reg);
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
+	      dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	      fs->regs.reg[reg] = fs->initial.reg[reg];
+	      break;
+
+	    case DW_CFA_undefined:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
+	      dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	      fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNDEFINED;
+	      break;
+
+	    case DW_CFA_same_value:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
+	      dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	      fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAME_VALUE;
+	      break;
+
+	    case DW_CFA_register:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
+	      dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	      fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG;
+	      fs->regs.reg[reg].loc.reg = utmp;
+	      break;
+
+	    case DW_CFA_remember_state:
+	      {
+		struct dwarf2_frame_state_reg_info *new_rs;
+
+		new_rs = XMALLOC (struct dwarf2_frame_state_reg_info);
+		*new_rs = fs->regs;
+		fs->regs.reg = dwarf2_frame_state_copy_regs (&fs->regs);
+		fs->regs.prev = new_rs;
+	      }
+	      break;
+
+	    case DW_CFA_restore_state:
+	      {
+		struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev;
+
+		gdb_assert (old_rs);
+
+		xfree (fs->regs.reg);
+		fs->regs = *old_rs;
+		xfree (old_rs);
+	      }
+	      break;
+
+	    case DW_CFA_def_cfa:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
+	      fs->cfa_offset = utmp;
+	      fs->cfa_how = CFA_REG_OFFSET;
+	      break;
+
+	    case DW_CFA_def_cfa_register:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
+	      fs->cfa_how = CFA_REG_OFFSET;
+	      break;
+
+	    case DW_CFA_def_cfa_offset:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_offset);
+	      /* cfa_how deliberately not set.  */
+	      break;
+
+	    case DW_CFA_nop:
+	      break;
+
+	    case DW_CFA_def_cfa_expression:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_exp_len);
+	      fs->cfa_exp = insn_ptr;
+	      fs->cfa_how = CFA_EXP;
+	      insn_ptr += fs->cfa_exp_len;
+	      break;
+
+	    case DW_CFA_expression:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
+	      dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
+	      fs->regs.reg[reg].loc.exp = insn_ptr;
+	      fs->regs.reg[reg].exp_len = utmp;
+	      fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_EXP;
+	      insn_ptr += utmp;
+	      break;
+
+	    case DW_CFA_offset_extended_sf:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
+	      insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
+	      offset += fs->data_align;
+	      dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	      fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
+	      fs->regs.reg[reg].loc.offset = offset;
+	      break;
+
+	    case DW_CFA_def_cfa_sf:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
+	      insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
+	      fs->cfa_offset = offset * fs->data_align;
+	      fs->cfa_how = CFA_REG_OFFSET;
+	      break;
+
+	    case DW_CFA_def_cfa_offset_sf:
+	      insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
+	      fs->cfa_offset = offset * fs->data_align;
+	      /* cfa_how deliberately not set.  */
+	      break;
+
+	    case DW_CFA_GNU_args_size:
+	      /* Ignored.  */
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
+	      break;
+
+	    default:
+	      internal_error (__FILE__, __LINE__, "Unknown CFI encountered.");
+	    }
+	}
+    }
+
+  /* Don't allow remember/restore between CIE and FDE programs.  */
+  dwarf2_frame_state_free_regs (fs->regs.prev);
+  fs->regs.prev = NULL;
+}
+
+
+/* Architecture-specific operations.  */
+
+/* Per-architecture data key.  */
+static struct gdbarch_data *dwarf2_frame_data;
+
+struct dwarf2_frame_ops
+{
+  /* Pre-initialize the register state REG for register REGNUM.  */
+  void (*init_reg) (struct gdbarch *, int, struct dwarf2_frame_state_reg *);
+};
+
+/* Default architecture-specific register state initialization
+   function.  */
+
+static void
+dwarf2_frame_default_init_reg (struct gdbarch *gdbarch, int regnum,
+			       struct dwarf2_frame_state_reg *reg)
+{
+  /* If we have a register that acts as a program counter, mark it as
+     a destination for the return address.  If we have a register that
+     serves as the stack pointer, arrange for it to be filled with the
+     call frame address (CFA).  The other registers are marked as
+     unspecified.
+
+     We copy the return address to the program counter, since many
+     parts in GDB assume that it is possible to get the return address
+     by unwinding the program counter register.  However, on ISA's
+     with a dedicated return address register, the CFI usually only
+     contains information to unwind that return address register.
+
+     The reason we're treating the stack pointer special here is
+     because in many cases GCC doesn't emit CFI for the stack pointer
+     and implicitly assumes that it is equal to the CFA.  This makes
+     some sense since the DWARF specification (version 3, draft 8,
+     p. 102) says that:
+
+     "Typically, the CFA is defined to be the value of the stack
+     pointer at the call site in the previous frame (which may be
+     different from its value on entry to the current frame)."
+
+     However, this isn't true for all platforms supported by GCC
+     (e.g. IBM S/390 and zSeries).  Those architectures should provide
+     their own architecture-specific initialization function.  */
+
+  if (regnum == PC_REGNUM)
+    reg->how = DWARF2_FRAME_REG_RA;
+  else if (regnum == SP_REGNUM)
+    reg->how = DWARF2_FRAME_REG_CFA;
+}
+
+/* Return a default for the architecture-specific operations.  */
+
+static void *
+dwarf2_frame_init (struct gdbarch *gdbarch)
+{
+  struct dwarf2_frame_ops *ops;
+  
+  ops = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct dwarf2_frame_ops);
+  ops->init_reg = dwarf2_frame_default_init_reg;
+  return ops;
+}
+
+static struct dwarf2_frame_ops *
+dwarf2_frame_ops (struct gdbarch *gdbarch)
+{
+  struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
+  if (ops == NULL)
+    {
+      /* ULGH, called during architecture initialization.  Patch
+         things up.  */
+      ops = dwarf2_frame_init (gdbarch);
+      set_gdbarch_data (gdbarch, dwarf2_frame_data, ops);
+    }
+  return ops;
+}
+
+/* Set the architecture-specific register state initialization
+   function for GDBARCH to INIT_REG.  */
+
+void
+dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
+			   void (*init_reg) (struct gdbarch *, int,
+					     struct dwarf2_frame_state_reg *))
+{
+  struct dwarf2_frame_ops *ops;
+
+  ops = dwarf2_frame_ops (gdbarch);
+  ops->init_reg = init_reg;
+}
+
+/* Pre-initialize the register state REG for register REGNUM.  */
+
+static void
+dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
+		       struct dwarf2_frame_state_reg *reg)
+{
+  struct dwarf2_frame_ops *ops;
+
+  ops = dwarf2_frame_ops (gdbarch);
+  ops->init_reg (gdbarch, regnum, reg);
+}
+
+
+struct dwarf2_frame_cache
+{
+  /* DWARF Call Frame Address.  */
+  CORE_ADDR cfa;
+
+  /* Saved registers, indexed by GDB register number, not by DWARF
+     register number.  */
+  struct dwarf2_frame_state_reg *reg;
+};
+
+static struct dwarf2_frame_cache *
+dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache)
+{
+  struct cleanup *old_chain;
+  struct gdbarch *gdbarch = get_frame_arch (next_frame);
+  const int num_regs = NUM_REGS + NUM_PSEUDO_REGS;
+  struct dwarf2_frame_cache *cache;
+  struct dwarf2_frame_state *fs;
+  struct dwarf2_fde *fde;
+
+  if (*this_cache)
+    return *this_cache;
+
+  /* Allocate a new cache.  */
+  cache = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache);
+  cache->reg = FRAME_OBSTACK_CALLOC (num_regs, struct dwarf2_frame_state_reg);
+
+  /* Allocate and initialize the frame state.  */
+  fs = XMALLOC (struct dwarf2_frame_state);
+  memset (fs, 0, sizeof (struct dwarf2_frame_state));
+  old_chain = make_cleanup (dwarf2_frame_state_free, fs);
+
+  /* Unwind the PC.
+
+     Note that if NEXT_FRAME is never supposed to return (i.e. a call
+     to abort), the compiler might optimize away the instruction at
+     NEXT_FRAME's return address.  As a result the return address will
+     point at some random instruction, and the CFI for that
+     instruction is probably worthless to us.  GCC's unwinder solves
+     this problem by substracting 1 from the return address to get an
+     address in the middle of a presumed call instruction (or the
+     instruction in the associated delay slot).  This should only be
+     done for "normal" frames and not for resume-type frames (signal
+     handlers, sentinel frames, dummy frames).  The function
+     frame_unwind_address_in_block does just this.  It's not clear how
+     reliable the method is though; there is the potential for the
+     register state pre-call being different to that on return.  */
+  fs->pc = frame_unwind_address_in_block (next_frame);
+
+  /* Find the correct FDE.  */
+  fde = dwarf2_frame_find_fde (&fs->pc);
+  gdb_assert (fde != NULL);
+
+  /* Extract any interesting information from the CIE.  */
+  fs->data_align = fde->cie->data_alignment_factor;
+  fs->code_align = fde->cie->code_alignment_factor;
+  fs->retaddr_column = fde->cie->return_address_register;
+
+  /* First decode all the insns in the CIE.  */
+  execute_cfa_program (fde->cie->initial_instructions,
+		       fde->cie->end, next_frame, fs);
+
+  /* Save the initialized register set.  */
+  fs->initial = fs->regs;
+  fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs);
+
+  /* Then decode the insns in the FDE up to our target PC.  */
+  execute_cfa_program (fde->instructions, fde->end, next_frame, fs);
+
+  /* Caclulate the CFA.  */
+  switch (fs->cfa_how)
+    {
+    case CFA_REG_OFFSET:
+      cache->cfa = read_reg (next_frame, fs->cfa_reg);
+      cache->cfa += fs->cfa_offset;
+      break;
+
+    case CFA_EXP:
+      cache->cfa =
+	execute_stack_op (fs->cfa_exp, fs->cfa_exp_len, next_frame, 0);
+      break;
+
+    default:
+      internal_error (__FILE__, __LINE__, "Unknown CFA rule.");
+    }
+
+  /* Initialize the register state.  */
+  {
+    int regnum;
+
+    for (regnum = 0; regnum < num_regs; regnum++)
+      dwarf2_frame_init_reg (gdbarch, regnum, &cache->reg[regnum]);
+  }
+
+  /* Go through the DWARF2 CFI generated table and save its register
+     location information in the cache.  Note that we don't skip the
+     return address column; it's perfectly all right for it to
+     correspond to a real register.  If it doesn't correspond to a
+     real register, or if we shouldn't treat it as such,
+     DWARF2_REG_TO_REGNUM should be defined to return a number outside
+     the range [0, NUM_REGS).  */
+  {
+    int column;		/* CFI speak for "register number".  */
+
+    for (column = 0; column < fs->regs.num_regs; column++)
+      {
+	/* Use the GDB register number as the destination index.  */
+	int regnum = DWARF2_REG_TO_REGNUM (column);
+
+	/* If there's no corresponding GDB register, ignore it.  */
+	if (regnum < 0 || regnum >= num_regs)
+	  continue;
+
+	/* NOTE: cagney/2003-09-05: CFI should specify the disposition
+	   of all debug info registers.  If it doesn't, complain (but
+	   not too loudly).  It turns out that GCC assumes that an
+	   unspecified register implies "same value" when CFI (draft
+	   7) specifies nothing at all.  Such a register could equally
+	   be interpreted as "undefined".  Also note that this check
+	   isn't sufficient; it only checks that all registers in the
+	   range [0 .. max column] are specified, and won't detect
+	   problems when a debug info register falls outside of the
+	   table.  We need a way of iterating through all the valid
+	   DWARF2 register numbers.  */
+	if (fs->regs.reg[column].how == DWARF2_FRAME_REG_UNSPECIFIED)
+	  complaint (&symfile_complaints,
+		     "Incomplete CFI data; unspecified registers at 0x%s",
+		     paddr (fs->pc));
+	else
+	  cache->reg[regnum] = fs->regs.reg[column];
+      }
+  }
+
+  /* Eliminate any DWARF2_FRAME_REG_RA rules.  */
+  {
+    int regnum;
+
+    for (regnum = 0; regnum < num_regs; regnum++)
+      {
+	if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
+	  {
+	    struct dwarf2_frame_state_reg *retaddr_reg =
+	      &fs->regs.reg[fs->retaddr_column];
+
+	    /* It seems rather bizarre to specify an "empty" column as
+               the return adress column.  However, this is exactly
+               what GCC does on some targets.  It turns out that GCC
+               assumes that the return address can be found in the
+               register corresponding to the return address column.
+               Incidentally, that's how should treat a return address
+               column specifying "same value" too.  */
+	    if (fs->retaddr_column < fs->regs.num_regs
+		&& retaddr_reg->how != DWARF2_FRAME_REG_UNSPECIFIED
+		&& retaddr_reg->how != DWARF2_FRAME_REG_SAME_VALUE)
+	      cache->reg[regnum] = *retaddr_reg;
+	    else
+	      {
+		cache->reg[regnum].loc.reg = fs->retaddr_column;
+		cache->reg[regnum].how = DWARF2_FRAME_REG_SAVED_REG;
+	      }
+	  }
+      }
+  }
+
+  do_cleanups (old_chain);
+
+  *this_cache = cache;
+  return cache;
+}
+
+static void
+dwarf2_frame_this_id (struct frame_info *next_frame, void **this_cache,
+		      struct frame_id *this_id)
+{
+  struct dwarf2_frame_cache *cache =
+    dwarf2_frame_cache (next_frame, this_cache);
+
+  (*this_id) = frame_id_build (cache->cfa, frame_func_unwind (next_frame));
+}
+
+static void
+dwarf2_frame_prev_register (struct frame_info *next_frame, void **this_cache,
+			    int regnum, int *optimizedp,
+			    enum lval_type *lvalp, CORE_ADDR *addrp,
+			    int *realnump, void *valuep)
+{
+  struct gdbarch *gdbarch = get_frame_arch (next_frame);
+  struct dwarf2_frame_cache *cache =
+    dwarf2_frame_cache (next_frame, this_cache);
+
+  switch (cache->reg[regnum].how)
+    {
+    case DWARF2_FRAME_REG_UNDEFINED:
+      /* If CFI explicitly specified that the value isn't defined,
+	 mark it as optimized away; the value isn't available.  */
+      *optimizedp = 1;
+      *lvalp = not_lval;
+      *addrp = 0;
+      *realnump = -1;
+      if (valuep)
+	{
+	  /* In some cases, for example %eflags on the i386, we have
+	     to provide a sane value, even though this register wasn't
+	     saved.  Assume we can get it from NEXT_FRAME.  */
+	  frame_unwind_register (next_frame, regnum, valuep);
+	}
+      break;
+
+    case DWARF2_FRAME_REG_SAVED_OFFSET:
+      *optimizedp = 0;
+      *lvalp = lval_memory;
+      *addrp = cache->cfa + cache->reg[regnum].loc.offset;
+      *realnump = -1;
+      if (valuep)
+	{
+	  /* Read the value in from memory.  */
+	  read_memory (*addrp, valuep, register_size (gdbarch, regnum));
+	}
+      break;
+
+    case DWARF2_FRAME_REG_SAVED_REG:
+      regnum = DWARF2_REG_TO_REGNUM (cache->reg[regnum].loc.reg);
+      frame_register_unwind (next_frame, regnum,
+			     optimizedp, lvalp, addrp, realnump, valuep);
+      break;
+
+    case DWARF2_FRAME_REG_SAVED_EXP:
+      *optimizedp = 0;
+      *lvalp = lval_memory;
+      *addrp = execute_stack_op (cache->reg[regnum].loc.exp,
+				 cache->reg[regnum].exp_len,
+				 next_frame, cache->cfa);
+      *realnump = -1;
+      if (valuep)
+	{
+	  /* Read the value in from memory.  */
+	  read_memory (*addrp, valuep, register_size (gdbarch, regnum));
+	}
+      break;
+
+    case DWARF2_FRAME_REG_UNSPECIFIED:
+      /* GCC, in its infinite wisdom decided to not provide unwind
+	 information for registers that are "same value".  Since
+	 DWARF2 (3 draft 7) doesn't define such behavior, said
+	 registers are actually undefined (which is different to CFI
+	 "undefined").  Code above issues a complaint about this.
+	 Here just fudge the books, assume GCC, and that the value is
+	 more inner on the stack.  */
+      frame_register_unwind (next_frame, regnum,
+			     optimizedp, lvalp, addrp, realnump, valuep);
+      break;
+
+    case DWARF2_FRAME_REG_SAME_VALUE:
+      frame_register_unwind (next_frame, regnum,
+			     optimizedp, lvalp, addrp, realnump, valuep);
+      break;
+
+    case DWARF2_FRAME_REG_CFA:
+      *optimizedp = 0;
+      *lvalp = not_lval;
+      *addrp = 0;
+      *realnump = -1;
+      if (valuep)
+	{
+	  /* Store the value.  */
+	  store_typed_address (valuep, builtin_type_void_data_ptr, cache->cfa);
+	}
+      break;
+
+    default:
+      internal_error (__FILE__, __LINE__, "Unknown register rule.");
+    }
+}
+
+static const struct frame_unwind dwarf2_frame_unwind =
+{
+  NORMAL_FRAME,
+  dwarf2_frame_this_id,
+  dwarf2_frame_prev_register
+};
+
+const struct frame_unwind *
+dwarf2_frame_sniffer (struct frame_info *next_frame)
+{
+  /* Grab an address that is guarenteed to reside somewhere within the
+     function.  frame_pc_unwind(), for a no-return next function, can
+     end up returning something past the end of this function's body.  */
+  CORE_ADDR block_addr = frame_unwind_address_in_block (next_frame);
+  if (dwarf2_frame_find_fde (&block_addr))
+    return &dwarf2_frame_unwind;
+
+  return NULL;
+}
+
+
+/* There is no explicitly defined relationship between the CFA and the
+   location of frame's local variables and arguments/parameters.
+   Therefore, frame base methods on this page should probably only be
+   used as a last resort, just to avoid printing total garbage as a
+   response to the "info frame" command.  */
+
+static CORE_ADDR
+dwarf2_frame_base_address (struct frame_info *next_frame, void **this_cache)
+{
+  struct dwarf2_frame_cache *cache =
+    dwarf2_frame_cache (next_frame, this_cache);
+
+  return cache->cfa;
+}
+
+static const struct frame_base dwarf2_frame_base =
+{
+  &dwarf2_frame_unwind,
+  dwarf2_frame_base_address,
+  dwarf2_frame_base_address,
+  dwarf2_frame_base_address
+};
+
+const struct frame_base *
+dwarf2_frame_base_sniffer (struct frame_info *next_frame)
+{
+  CORE_ADDR pc = frame_pc_unwind (next_frame);
+  if (dwarf2_frame_find_fde (&pc))
+    return &dwarf2_frame_base;
+
+  return NULL;
+}
+
+/* A minimal decoding of DWARF2 compilation units.  We only decode
+   what's needed to get to the call frame information.  */
+
+struct comp_unit
+{
+  /* Keep the bfd convenient.  */
+  bfd *abfd;
+
+  struct objfile *objfile;
+
+  /* Linked list of CIEs for this object.  */
+  struct dwarf2_cie *cie;
+
+  /* Address size for this unit - from unit header.  */
+  unsigned char addr_size;
+
+  /* Pointer to the .debug_frame section loaded into memory.  */
+  char *dwarf_frame_buffer;
+
+  /* Length of the loaded .debug_frame section.  */
+  unsigned long dwarf_frame_size;
+
+  /* Pointer to the .debug_frame section.  */
+  asection *dwarf_frame_section;
+
+  /* Base for DW_EH_PE_datarel encodings.  */
+  bfd_vma dbase;
+
+  /* Base for DW_EH_PE_textrel encodings.  */
+  bfd_vma tbase;
+};
+
+const struct objfile_data *dwarf2_frame_objfile_data;
+
+static unsigned int
+read_1_byte (bfd *bfd, char *buf)
+{
+  return bfd_get_8 (abfd, (bfd_byte *) buf);
+}
+
+static unsigned int
+read_4_bytes (bfd *abfd, char *buf)
+{
+  return bfd_get_32 (abfd, (bfd_byte *) buf);
+}
+
+static ULONGEST
+read_8_bytes (bfd *abfd, char *buf)
+{
+  return bfd_get_64 (abfd, (bfd_byte *) buf);
+}
+
+static ULONGEST
+read_unsigned_leb128 (bfd *abfd, char *buf, unsigned int *bytes_read_ptr)
+{
+  ULONGEST result;
+  unsigned int num_read;
+  int shift;
+  unsigned char byte;
+
+  result = 0;
+  shift = 0;
+  num_read = 0;
+
+  do
+    {
+      byte = bfd_get_8 (abfd, (bfd_byte *) buf);
+      buf++;
+      num_read++;
+      result |= ((byte & 0x7f) << shift);
+      shift += 7;
+    }
+  while (byte & 0x80);
+
+  *bytes_read_ptr = num_read;
+
+  return result;
+}
+
+static LONGEST
+read_signed_leb128 (bfd *abfd, char *buf, unsigned int *bytes_read_ptr)
+{
+  LONGEST result;
+  int shift;
+  unsigned int num_read;
+  unsigned char byte;
+
+  result = 0;
+  shift = 0;
+  num_read = 0;
+
+  do
+    {
+      byte = bfd_get_8 (abfd, (bfd_byte *) buf);
+      buf++;
+      num_read++;
+      result |= ((byte & 0x7f) << shift);
+      shift += 7;
+    }
+  while (byte & 0x80);
+
+  if ((shift < 32) && (byte & 0x40))
+    result |= -(1 << shift);
+
+  *bytes_read_ptr = num_read;
+
+  return result;
+}
+
+static ULONGEST
+read_initial_length (bfd *abfd, char *buf, unsigned int *bytes_read_ptr)
+{
+  LONGEST result;
+
+  result = bfd_get_32 (abfd, (bfd_byte *) buf);
+  if (result == 0xffffffff)
+    {
+      result = bfd_get_64 (abfd, (bfd_byte *) buf + 4);
+      *bytes_read_ptr = 12;
+    }
+  else
+    *bytes_read_ptr = 4;
+
+  return result;
+}
+
+
+/* Pointer encoding helper functions.  */
+
+/* GCC supports exception handling based on DWARF2 CFI.  However, for
+   technical reasons, it encodes addresses in its FDE's in a different
+   way.  Several "pointer encodings" are supported.  The encoding
+   that's used for a particular FDE is determined by the 'R'
+   augmentation in the associated CIE.  The argument of this
+   augmentation is a single byte.  
+
+   The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a
+   LEB128.  This is encoded in bits 0, 1 and 2.  Bit 3 encodes whether
+   the address is signed or unsigned.  Bits 4, 5 and 6 encode how the
+   address should be interpreted (absolute, relative to the current
+   position in the FDE, ...).  Bit 7, indicates that the address
+   should be dereferenced.  */
+
+static unsigned char
+encoding_for_size (unsigned int size)
+{
+  switch (size)
+    {
+    case 2:
+      return DW_EH_PE_udata2;
+    case 4:
+      return DW_EH_PE_udata4;
+    case 8:
+      return DW_EH_PE_udata8;
+    default:
+      internal_error (__FILE__, __LINE__, "Unsupported address size");
+    }
+}
+
+static unsigned int
+size_of_encoded_value (unsigned char encoding)
+{
+  if (encoding == DW_EH_PE_omit)
+    return 0;
+
+  switch (encoding & 0x07)
+    {
+    case DW_EH_PE_absptr:
+      return TYPE_LENGTH (builtin_type_void_data_ptr);
+    case DW_EH_PE_udata2:
+      return 2;
+    case DW_EH_PE_udata4:
+      return 4;
+    case DW_EH_PE_udata8:
+      return 8;
+    default:
+      internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding");
+    }
+}
+
+static CORE_ADDR
+read_encoded_value (struct comp_unit *unit, unsigned char encoding,
+		    char *buf, unsigned int *bytes_read_ptr)
+{
+  int ptr_len = size_of_encoded_value (DW_EH_PE_absptr);
+  ptrdiff_t offset;
+  CORE_ADDR base;
+
+  /* GCC currently doesn't generate DW_EH_PE_indirect encodings for
+     FDE's.  */
+  if (encoding & DW_EH_PE_indirect)
+    internal_error (__FILE__, __LINE__, 
+		    "Unsupported encoding: DW_EH_PE_indirect");
+
+  *bytes_read_ptr = 0;
+
+  switch (encoding & 0x70)
+    {
+    case DW_EH_PE_absptr:
+      base = 0;
+      break;
+    case DW_EH_PE_pcrel:
+      base = bfd_get_section_vma (unit->bfd, unit->dwarf_frame_section);
+      base += (buf - unit->dwarf_frame_buffer);
+      break;
+    case DW_EH_PE_datarel:
+      base = unit->dbase;
+      break;
+    case DW_EH_PE_textrel:
+      base = unit->tbase;
+      break;
+    case DW_EH_PE_aligned:
+      base = 0;
+      offset = buf - unit->dwarf_frame_buffer;
+      if ((offset % ptr_len) != 0)
+	{
+	  *bytes_read_ptr = ptr_len - (offset % ptr_len);
+	  buf += *bytes_read_ptr;
+	}
+      break;
+    default:
+      internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding");
+    }
+
+  if ((encoding & 0x0f) == 0x00)
+    encoding |= encoding_for_size (ptr_len);
+
+  switch (encoding & 0x0f)
+    {
+    case DW_EH_PE_udata2:
+      *bytes_read_ptr += 2;
+      return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf));
+    case DW_EH_PE_udata4:
+      *bytes_read_ptr += 4;
+      return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf));
+    case DW_EH_PE_udata8:
+      *bytes_read_ptr += 8;
+      return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf));
+    case DW_EH_PE_sdata2:
+      *bytes_read_ptr += 2;
+      return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf));
+    case DW_EH_PE_sdata4:
+      *bytes_read_ptr += 4;
+      return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf));
+    case DW_EH_PE_sdata8:
+      *bytes_read_ptr += 8;
+      return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf));
+    default:
+      internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding");
+    }
+}
+
+
+/* GCC uses a single CIE for all FDEs in a .debug_frame section.
+   That's why we use a simple linked list here.  */
+
+static struct dwarf2_cie *
+find_cie (struct comp_unit *unit, ULONGEST cie_pointer)
+{
+  struct dwarf2_cie *cie = unit->cie;
+
+  while (cie)
+    {
+      if (cie->cie_pointer == cie_pointer)
+	return cie;
+
+      cie = cie->next;
+    }
+
+  return NULL;
+}
+
+static void
+add_cie (struct comp_unit *unit, struct dwarf2_cie *cie)
+{
+  cie->next = unit->cie;
+  unit->cie = cie;
+}
+
+/* Find the FDE for *PC.  Return a pointer to the FDE, and store the
+   inital location associated with it into *PC.  */
+
+static struct dwarf2_fde *
+dwarf2_frame_find_fde (CORE_ADDR *pc)
+{
+  struct objfile *objfile;
+
+  ALL_OBJFILES (objfile)
+    {
+      struct dwarf2_fde *fde;
+      CORE_ADDR offset;
+
+      fde = objfile_data (objfile, dwarf2_frame_objfile_data);
+      if (fde == NULL)
+	continue;
+
+      gdb_assert (objfile->section_offsets);
+      offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
+
+      while (fde)
+	{
+	  if (*pc >= fde->initial_location + offset
+	      && *pc < fde->initial_location + offset + fde->address_range)
+	    {
+	      *pc = fde->initial_location + offset;
+	      return fde;
+	    }
+
+	  fde = fde->next;
+	}
+    }
+
+  return NULL;
+}
+
+static void
+add_fde (struct comp_unit *unit, struct dwarf2_fde *fde)
+{
+  fde->next = objfile_data (unit->objfile, dwarf2_frame_objfile_data);
+  set_objfile_data (unit->objfile, dwarf2_frame_objfile_data, fde);
+}
+
+#ifdef CC_HAS_LONG_LONG
+#define DW64_CIE_ID 0xffffffffffffffffULL
+#else
+#define DW64_CIE_ID ~0
+#endif
+
+static char *decode_frame_entry (struct comp_unit *unit, char *start,
+				 int eh_frame_p);
+
+/* Decode the next CIE or FDE.  Return NULL if invalid input, otherwise
+   the next byte to be processed.  */
+static char *
+decode_frame_entry_1 (struct comp_unit *unit, char *start, int eh_frame_p)
+{
+  char *buf;
+  LONGEST length;
+  unsigned int bytes_read;
+  int dwarf64_p;
+  ULONGEST cie_id;
+  ULONGEST cie_pointer;
+  char *end;
+
+  buf = start;
+  length = read_initial_length (unit->abfd, buf, &bytes_read);
+  buf += bytes_read;
+  end = buf + length;
+
+  /* Are we still within the section? */
+  if (end > unit->dwarf_frame_buffer + unit->dwarf_frame_size)
+    return NULL;
+
+  if (length == 0)
+    return end;
+
+  /* Distinguish between 32 and 64-bit encoded frame info.  */
+  dwarf64_p = (bytes_read == 12);
+
+  /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs.  */
+  if (eh_frame_p)
+    cie_id = 0;
+  else if (dwarf64_p)
+    cie_id = DW64_CIE_ID;
+  else
+    cie_id = DW_CIE_ID;
+
+  if (dwarf64_p)
+    {
+      cie_pointer = read_8_bytes (unit->abfd, buf);
+      buf += 8;
+    }
+  else
+    {
+      cie_pointer = read_4_bytes (unit->abfd, buf);
+      buf += 4;
+    }
+
+  if (cie_pointer == cie_id)
+    {
+      /* This is a CIE.  */
+      struct dwarf2_cie *cie;
+      char *augmentation;
+
+      /* Record the offset into the .debug_frame section of this CIE.  */
+      cie_pointer = start - unit->dwarf_frame_buffer;
+
+      /* Check whether we've already read it.  */
+      if (find_cie (unit, cie_pointer))
+	return end;
+
+      cie = (struct dwarf2_cie *)
+	obstack_alloc (&unit->objfile->objfile_obstack,
+		       sizeof (struct dwarf2_cie));
+      cie->initial_instructions = NULL;
+      cie->cie_pointer = cie_pointer;
+
+      /* The encoding for FDE's in a normal .debug_frame section
+         depends on the target address size as specified in the
+         Compilation Unit Header.  */
+      cie->encoding = encoding_for_size (unit->addr_size);
+
+      /* Check version number.  */
+      if (read_1_byte (unit->abfd, buf) != DW_CIE_VERSION)
+	return NULL;
+      buf += 1;
+
+      /* Interpret the interesting bits of the augmentation.  */
+      augmentation = buf;
+      buf = augmentation + strlen (augmentation) + 1;
+
+      /* The GCC 2.x "eh" augmentation has a pointer immediately
+         following the augmentation string, so it must be handled
+         first.  */
+      if (augmentation[0] == 'e' && augmentation[1] == 'h')
+	{
+	  /* Skip.  */
+	  buf += TYPE_LENGTH (builtin_type_void_data_ptr);
+	  augmentation += 2;
+	}
+
+      cie->code_alignment_factor =
+	read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
+      buf += bytes_read;
+
+      cie->data_alignment_factor =
+	read_signed_leb128 (unit->abfd, buf, &bytes_read);
+      buf += bytes_read;
+
+      cie->return_address_register = read_1_byte (unit->abfd, buf);
+      buf += 1;
+
+      cie->saw_z_augmentation = (*augmentation == 'z');
+      if (cie->saw_z_augmentation)
+	{
+	  ULONGEST length;
+
+	  length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
+	  buf += bytes_read;
+	  if (buf > end)
+	    return NULL;
+	  cie->initial_instructions = buf + length;
+	  augmentation++;
+	}
+
+      while (*augmentation)
+	{
+	  /* "L" indicates a byte showing how the LSDA pointer is encoded.  */
+	  if (*augmentation == 'L')
+	    {
+	      /* Skip.  */
+	      buf++;
+	      augmentation++;
+	    }
+
+	  /* "R" indicates a byte indicating how FDE addresses are encoded.  */
+	  else if (*augmentation == 'R')
+	    {
+	      cie->encoding = *buf++;
+	      augmentation++;
+	    }
+
+	  /* "P" indicates a personality routine in the CIE augmentation.  */
+	  else if (*augmentation == 'P')
+	    {
+	      /* Skip.  */
+	      buf += size_of_encoded_value (*buf++);
+	      augmentation++;
+	    }
+
+	  /* Otherwise we have an unknown augmentation.
+	     Bail out unless we saw a 'z' prefix.  */
+	  else
+	    {
+	      if (cie->initial_instructions == NULL)
+		return end;
+
+	      /* Skip unknown augmentations.  */
+	      buf = cie->initial_instructions;
+	      break;
+	    }
+	}
+
+      cie->initial_instructions = buf;
+      cie->end = end;
+
+      add_cie (unit, cie);
+    }
+  else
+    {
+      /* This is a FDE.  */
+      struct dwarf2_fde *fde;
+
+      /* In an .eh_frame section, the CIE pointer is the delta between the
+	 address within the FDE where the CIE pointer is stored and the
+	 address of the CIE.  Convert it to an offset into the .eh_frame
+	 section.  */
+      if (eh_frame_p)
+	{
+	  cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer;
+	  cie_pointer -= (dwarf64_p ? 8 : 4);
+	}
+
+      /* In either case, validate the result is still within the section.  */
+      if (cie_pointer >= unit->dwarf_frame_size)
+	return NULL;
+
+      fde = (struct dwarf2_fde *)
+	obstack_alloc (&unit->objfile->objfile_obstack,
+		       sizeof (struct dwarf2_fde));
+      fde->cie = find_cie (unit, cie_pointer);
+      if (fde->cie == NULL)
+	{
+	  decode_frame_entry (unit, unit->dwarf_frame_buffer + cie_pointer,
+			      eh_frame_p);
+	  fde->cie = find_cie (unit, cie_pointer);
+	}
+
+      gdb_assert (fde->cie != NULL);
+
+      fde->initial_location =
+	read_encoded_value (unit, fde->cie->encoding, buf, &bytes_read);
+      buf += bytes_read;
+
+      fde->address_range =
+	read_encoded_value (unit, fde->cie->encoding & 0x0f, buf, &bytes_read);
+      buf += bytes_read;
+
+      /* A 'z' augmentation in the CIE implies the presence of an
+	 augmentation field in the FDE as well.  The only thing known
+	 to be in here at present is the LSDA entry for EH.  So we
+	 can skip the whole thing.  */
+      if (fde->cie->saw_z_augmentation)
+	{
+	  ULONGEST length;
+
+	  length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
+	  buf += bytes_read + length;
+	  if (buf > end)
+	    return NULL;
+	}
+
+      fde->instructions = buf;
+      fde->end = end;
+
+      add_fde (unit, fde);
+    }
+
+  return end;
+}
+
+/* Read a CIE or FDE in BUF and decode it.  */
+static char *
+decode_frame_entry (struct comp_unit *unit, char *start, int eh_frame_p)
+{
+  enum { NONE, ALIGN4, ALIGN8, FAIL } workaround = NONE;
+  char *ret;
+  const char *msg;
+  ptrdiff_t start_offset;
+
+  while (1)
+    {
+      ret = decode_frame_entry_1 (unit, start, eh_frame_p);
+      if (ret != NULL)
+	break;
+
+      /* We have corrupt input data of some form.  */
+
+      /* ??? Try, weakly, to work around compiler/assembler/linker bugs
+	 and mismatches wrt padding and alignment of debug sections.  */
+      /* Note that there is no requirement in the standard for any
+	 alignment at all in the frame unwind sections.  Testing for
+	 alignment before trying to interpret data would be incorrect.
+
+	 However, GCC traditionally arranged for frame sections to be
+	 sized such that the FDE length and CIE fields happen to be
+	 aligned (in theory, for performance).  This, unfortunately,
+	 was done with .align directives, which had the side effect of
+	 forcing the section to be aligned by the linker.
+
+	 This becomes a problem when you have some other producer that
+	 creates frame sections that are not as strictly aligned.  That
+	 produces a hole in the frame info that gets filled by the 
+	 linker with zeros.
+
+	 The GCC behaviour is arguably a bug, but it's effectively now
+	 part of the ABI, so we're now stuck with it, at least at the
+	 object file level.  A smart linker may decide, in the process
+	 of compressing duplicate CIE information, that it can rewrite
+	 the entire output section without this extra padding.  */
+
+      start_offset = start - unit->dwarf_frame_buffer;
+      if (workaround < ALIGN4 && (start_offset & 3) != 0)
+	{
+	  start += 4 - (start_offset & 3);
+	  workaround = ALIGN4;
+	  continue;
+	}
+      if (workaround < ALIGN8 && (start_offset & 7) != 0)
+	{
+	  start += 8 - (start_offset & 7);
+	  workaround = ALIGN8;
+	  continue;
+	}
+
+      /* Nothing left to try.  Arrange to return as if we've consumed
+	 the entire input section.  Hopefully we'll get valid info from
+	 the other of .debug_frame/.eh_frame.  */
+      workaround = FAIL;
+      ret = unit->dwarf_frame_buffer + unit->dwarf_frame_size;
+      break;
+    }
+
+  switch (workaround)
+    {
+    case NONE:
+      break;
+
+    case ALIGN4:
+      complaint (&symfile_complaints,
+		 "Corrupt data in %s:%s; align 4 workaround apparently succeeded",
+		 unit->dwarf_frame_section->owner->filename,
+		 unit->dwarf_frame_section->name);
+      break;
+
+    case ALIGN8:
+      complaint (&symfile_complaints,
+		 "Corrupt data in %s:%s; align 8 workaround apparently succeeded",
+		 unit->dwarf_frame_section->owner->filename,
+		 unit->dwarf_frame_section->name);
+      break;
+
+    default:
+      complaint (&symfile_complaints,
+		 "Corrupt data in %s:%s",
+		 unit->dwarf_frame_section->owner->filename,
+		 unit->dwarf_frame_section->name);
+      break;
+    }
+
+  return ret;
+}
+
+
+/* FIXME: kettenis/20030504: This still needs to be integrated with
+   dwarf2read.c in a better way.  */
+
+/* Imported from dwarf2read.c.  */
+extern asection *dwarf_frame_section;
+extern asection *dwarf_eh_frame_section;
+
+/* Imported from dwarf2read.c.  */
+extern char *dwarf2_read_section (struct objfile *objfile, asection *sectp);
+
+void
+dwarf2_build_frame_info (struct objfile *objfile)
+{
+  struct comp_unit unit;
+  char *frame_ptr;
+
+  /* Build a minimal decoding of the DWARF2 compilation unit.  */
+  unit.abfd = objfile->obfd;
+  unit.objfile = objfile;
+  unit.addr_size = objfile->obfd->arch_info->bits_per_address / 8;
+  unit.dbase = 0;
+  unit.tbase = 0;
+
+  /* First add the information from the .eh_frame section.  That way,
+     the FDEs from that section are searched last.  */
+  if (dwarf_eh_frame_section)
+    {
+      asection *got, *txt;
+
+      unit.cie = NULL;
+      unit.dwarf_frame_buffer = dwarf2_read_section (objfile,
+						     dwarf_eh_frame_section);
+
+      unit.dwarf_frame_size
+	= bfd_get_section_size_before_reloc (dwarf_eh_frame_section);
+      unit.dwarf_frame_section = dwarf_eh_frame_section;
+
+      /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
+	 that is used for the i386/amd64 target, which currently is
+	 the only target in GCC that supports/uses the
+	 DW_EH_PE_datarel encoding.  */
+      got = bfd_get_section_by_name (unit.abfd, ".got");
+      if (got)
+	unit.dbase = got->vma;
+
+      /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
+         so far.  */
+      txt = bfd_get_section_by_name (unit.abfd, ".text");
+      if (txt)
+	unit.tbase = txt->vma;
+
+      frame_ptr = unit.dwarf_frame_buffer;
+      while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size)
+	frame_ptr = decode_frame_entry (&unit, frame_ptr, 1);
+    }
+
+  if (dwarf_frame_section)
+    {
+      unit.cie = NULL;
+      unit.dwarf_frame_buffer = dwarf2_read_section (objfile,
+						     dwarf_frame_section);
+      unit.dwarf_frame_size
+	= bfd_get_section_size_before_reloc (dwarf_frame_section);
+      unit.dwarf_frame_section = dwarf_frame_section;
+
+      frame_ptr = unit.dwarf_frame_buffer;
+      while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size)
+	frame_ptr = decode_frame_entry (&unit, frame_ptr, 0);
+    }
+}
+
+/* Provide a prototype to silence -Wmissing-prototypes.  */
+void _initialize_dwarf2_frame (void);
+
+void
+_initialize_dwarf2_frame (void)
+{
+  dwarf2_frame_data = register_gdbarch_data (dwarf2_frame_init);
+  dwarf2_frame_objfile_data = register_objfile_data ();
+}