[PATCH 33/43] Remove old computed struct value callbacks

[Zoran Zaric via Gdb-patches <gdb-patches@sourceware.org>]

After changing the DWARF stack to use the new DWARF entry based
classes, the previous computed struct value callback
infrastructure is not used anymore and can be removed.

gdb/ChangeLog:

        * dwarf2/expr.c (struct piece_closure): Remove structure.
        (rw_pieced_value): Remove unused function.
        (read_pieced_value): Remove unused function.
        (write_pieced_value): Remove unused function.
        (check_pieced_synthetic_pointer): Remove unused function.
        (indirect_pieced_value): Remove unused function.
        (coerce_pieced_ref): Remove unused function.
        (copy_pieced_value_closure): Remove unused function.
        (free_pieced_value_closure): Remove unused function.
        * dwarf2/expr.h (class dwarf_entry): New declaration.
        (struct dwarf_expr_piece): Remove structure.
        (enum dwarf_value_location): Remove enumeration.
---
 gdb/dwarf2/expr.c | 519 ----------------------------------------------
 gdb/dwarf2/expr.h |  72 -------
 2 files changed, 591 deletions(-)

diff --git a/gdb/dwarf2/expr.c b/gdb/dwarf2/expr.c
index d51366007ab..e45a7755ec5 100644
--- a/gdb/dwarf2/expr.c
+++ b/gdb/dwarf2/expr.c
@@ -2194,525 +2194,6 @@ gdb_value_to_dwarf_entry (struct gdbarch *arch, struct value *value)
   }
 }
 
-struct piece_closure
-{
-  /* Reference count.  */
-  int refc = 0;
-
-  /* The objfile from which this closure's expression came.  */
-  dwarf2_per_objfile *per_objfile = nullptr;
-
-  /* The CU from which this closure's expression came.  */
-  struct dwarf2_per_cu_data *per_cu = NULL;
-
-  /* The pieces describing this variable.  */
-  std::vector<dwarf_expr_piece> pieces;
-
-  /* Frame ID of frame to which a register value is relative, used
-     only by DWARF_VALUE_REGISTER.  */
-  struct frame_id frame_id;
-};
-
-/* Read or write a pieced value V.  If FROM != NULL, operate in "write
-   mode": copy FROM into the pieces comprising V.  If FROM == NULL,
-   operate in "read mode": fetch the contents of the (lazy) value V by
-   composing it from its pieces.  */
-
-static void
-rw_pieced_value (struct value *v, struct value *from)
-{
-  int i;
-  LONGEST offset = 0, max_offset;
-  ULONGEST bits_to_skip;
-  gdb_byte *v_contents;
-  const gdb_byte *from_contents;
-  struct piece_closure *c
-    = (struct piece_closure *) value_computed_closure (v);
-  gdb::byte_vector buffer;
-  bool bits_big_endian = type_byte_order (value_type (v)) == BFD_ENDIAN_BIG;
-
-  if (from != NULL)
-    {
-      from_contents = value_contents (from);
-      v_contents = NULL;
-    }
-  else
-    {
-      if (value_type (v) != value_enclosing_type (v))
-	internal_error (__FILE__, __LINE__,
-			_("Should not be able to create a lazy value with "
-			  "an enclosing type"));
-      v_contents = value_contents_raw (v);
-      from_contents = NULL;
-    }
-
-  bits_to_skip = 8 * value_offset (v);
-  if (value_bitsize (v))
-    {
-      bits_to_skip += (8 * value_offset (value_parent (v))
-		       + value_bitpos (v));
-      if (from != NULL
-	  && (type_byte_order (value_type (from))
-	      == BFD_ENDIAN_BIG))
-	{
-	  /* Use the least significant bits of FROM.  */
-	  max_offset = 8 * TYPE_LENGTH (value_type (from));
-	  offset = max_offset - value_bitsize (v);
-	}
-      else
-	max_offset = value_bitsize (v);
-    }
-  else
-    max_offset = 8 * TYPE_LENGTH (value_type (v));
-
-  /* Advance to the first non-skipped piece.  */
-  for (i = 0; i < c->pieces.size () && bits_to_skip >= c->pieces[i].size; i++)
-    bits_to_skip -= c->pieces[i].size;
-
-  for (; i < c->pieces.size () && offset < max_offset; i++)
-    {
-      struct dwarf_expr_piece *p = &c->pieces[i];
-      size_t this_size_bits, this_size;
-
-      this_size_bits = p->size - bits_to_skip;
-      if (this_size_bits > max_offset - offset)
-	this_size_bits = max_offset - offset;
-
-      switch (p->location)
-	{
-	case DWARF_VALUE_REGISTER:
-	  {
-	    struct frame_info *frame = frame_find_by_id (c->frame_id);
-	    struct gdbarch *arch = get_frame_arch (frame);
-	    int gdb_regnum = dwarf_reg_to_regnum_or_error (arch, p->v.regno);
-	    ULONGEST reg_bits = 8 * register_size (arch, gdb_regnum);
-	    int optim, unavail;
-
-	    if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG
-		&& p->offset + p->size < reg_bits)
-	      {
-		/* Big-endian, and we want less than full size.  */
-		bits_to_skip += reg_bits - (p->offset + p->size);
-	      }
-	    else
-	      bits_to_skip += p->offset;
-
-	    this_size = bits_to_bytes (bits_to_skip, this_size_bits);
-	    buffer.resize (this_size);
-
-	    if (from == NULL)
-	      {
-		/* Read mode.  */
-		read_from_register (frame, gdb_regnum, bits_to_skip / 8,
-				    buffer, &optim, &unavail);
-
-		if (optim)
-		  mark_value_bits_optimized_out (v, offset, this_size_bits);
-		if (unavail)
-		  mark_value_bits_unavailable (v, offset, this_size_bits);
-		/* Only copy data if valid.  */
-		if (!optim && !unavail)
-		  copy_bitwise (v_contents, offset,
-				buffer.data (), bits_to_skip % 8,
-				this_size_bits, bits_big_endian);
-	      }
-	    else
-	      {
-		/* Write mode.  */
-		if (bits_to_skip % 8 != 0 || this_size_bits % 8 != 0)
-		  {
-		    /* Data is copied non-byte-aligned into the register.
-		       Need some bits from original register value.  */
-		    read_from_register (frame, gdb_regnum, bits_to_skip / 8,
-					buffer, &optim, &unavail);
-		    if (optim)
-		      throw_error (OPTIMIZED_OUT_ERROR,
-				   _("Can't do read-modify-write to "
-				     "update bitfield; containing word "
-				     "has been optimized out"));
-		    if (unavail)
-		      throw_error (NOT_AVAILABLE_ERROR,
-				   _("Can't do read-modify-write to "
-				     "update bitfield; containing word "
-				     "is unavailable"));
-		  }
-
-		copy_bitwise (buffer.data (), bits_to_skip % 8,
-			      from_contents, offset,
-			      this_size_bits, bits_big_endian);
-		write_to_register (frame, gdb_regnum, bits_to_skip / 8,
-				   buffer, &optim, &unavail);
-	      }
-	  }
-	  break;
-
-	case DWARF_VALUE_MEMORY:
-	  {
-	    bits_to_skip += p->offset;
-
-	    CORE_ADDR start_addr = p->v.mem.addr + bits_to_skip / 8;
-	    bool in_stack_memory = p->v.mem.in_stack_memory;
-	    int unavail = 0;
-
-	    if (bits_to_skip % 8 == 0 && this_size_bits % 8 == 0
-		&& offset % 8 == 0)
-	      {
-		/* Everything is byte-aligned; no buffer needed.  */
-		if (from != NULL)
-		  write_to_memory (start_addr, (from_contents + offset / 8),
-				   this_size_bits / 8, in_stack_memory,
-				   &unavail);
-		else
-		  read_from_memory (start_addr, (v_contents + offset / 8),
-				    this_size_bits / 8, in_stack_memory,
-				    &unavail);
-	      }
-	    else
-	      {
-		this_size = bits_to_bytes (bits_to_skip, this_size_bits);
-		buffer.resize (this_size);
-
-		if (from == NULL)
-		  {
-		    /* Read mode.  */
-		    read_from_memory (start_addr, buffer.data (),
-				      this_size, in_stack_memory,
-				      &unavail);
-		    if (!unavail)
-		      copy_bitwise (v_contents, offset,
-				    buffer.data (), bits_to_skip % 8,
-				    this_size_bits, bits_big_endian);
-		  }
-		else
-		  {
-		    /* Write mode.  */
-		    if (bits_to_skip % 8 != 0 || this_size_bits % 8 != 0)
-		      {
-			if (this_size <= 8)
-			  {
-			    /* Perform a single read for small sizes.  */
-			    read_from_memory (start_addr, buffer.data (),
-					      this_size, in_stack_memory,
-					      &unavail);
-			  }
-			else
-			  {
-			    /* Only the first and last bytes can possibly have
-			       any bits reused.  */
-			    read_from_memory (start_addr, buffer.data (),
-					      1, in_stack_memory,
-					      &unavail);
-			    if (!unavail)
-			      read_from_memory (start_addr + this_size - 1,
-						&buffer[this_size - 1], 1,
-						in_stack_memory, &unavail);
-			  }
-		      }
-
-		    if (!unavail)
-		      {
-			copy_bitwise (buffer.data (), bits_to_skip % 8,
-				      from_contents, offset,
-				      this_size_bits, bits_big_endian);
-			write_to_memory (start_addr, buffer.data (),
-					 this_size, in_stack_memory,
-					 &unavail);
-		      }
-		  }
-	      }
-
-	    if (unavail)
-	      {
-		if (from == NULL)
-		  mark_value_bits_unavailable (v, (offset + bits_to_skip % 8),
-					       this_size_bits);
-		else
-		  throw_error (NOT_AVAILABLE_ERROR,
-			       _("Can't do read-modify-write to "
-				 "update bitfield; containing word "
-				 "is unavailable"));
-	      }
-	  }
-	  break;
-
-	case DWARF_VALUE_STACK:
-	  {
-	    if (from != NULL)
-	      {
-		mark_value_bits_optimized_out (v, offset, this_size_bits);
-		break;
-	      }
-
-	    gdbarch *objfile_gdbarch = c->per_objfile->objfile->arch ();
-	    ULONGEST stack_value_size_bits
-	      = 8 * TYPE_LENGTH (value_type (p->v.value));
-
-	    /* Use zeroes if piece reaches beyond stack value.  */
-	    if (p->offset + p->size > stack_value_size_bits)
-	      break;
-
-	    /* Piece is anchored at least significant bit end.  */
-	    if (gdbarch_byte_order (objfile_gdbarch) == BFD_ENDIAN_BIG)
-	      bits_to_skip += stack_value_size_bits - p->offset - p->size;
-	    else
-	      bits_to_skip += p->offset;
-
-	    copy_bitwise (v_contents, offset,
-			  value_contents_all (p->v.value),
-			  bits_to_skip,
-			  this_size_bits, bits_big_endian);
-	  }
-	  break;
-
-	case DWARF_VALUE_LITERAL:
-	  {
-	    if (from != NULL)
-	      {
-		mark_value_bits_optimized_out (v, offset, this_size_bits);
-		break;
-	      }
-
-	    ULONGEST literal_size_bits = 8 * p->v.literal.length;
-	    size_t n = this_size_bits;
-
-	    /* Cut off at the end of the implicit value.  */
-	    bits_to_skip += p->offset;
-	    if (bits_to_skip >= literal_size_bits)
-	      break;
-	    if (n > literal_size_bits - bits_to_skip)
-	      n = literal_size_bits - bits_to_skip;
-
-	    copy_bitwise (v_contents, offset,
-			  p->v.literal.data, bits_to_skip,
-			  n, bits_big_endian);
-	  }
-	  break;
-
-	case DWARF_VALUE_IMPLICIT_POINTER:
-	    if (from != NULL)
-	      {
-		mark_value_bits_optimized_out (v, offset, this_size_bits);
-		break;
-	      }
-
-	  /* These bits show up as zeros -- but do not cause the value to
-	     be considered optimized-out.  */
-	  break;
-
-	case DWARF_VALUE_OPTIMIZED_OUT:
-	  mark_value_bits_optimized_out (v, offset, this_size_bits);
-	  break;
-
-	default:
-	  internal_error (__FILE__, __LINE__, _("invalid location type"));
-	}
-
-      offset += this_size_bits;
-      bits_to_skip = 0;
-    }
-}
-
-static void
-read_pieced_value (struct value *v)
-{
-  rw_pieced_value (v, NULL);
-}
-
-static void
-write_pieced_value (struct value *to, struct value *from)
-{
-  rw_pieced_value (to, from);
-}
-
-/* An implementation of an lval_funcs method to see whether a value is
-   a synthetic pointer.  */
-
-static int
-check_pieced_synthetic_pointer (const struct value *value, LONGEST bit_offset,
-				int bit_length)
-{
-  struct piece_closure *c
-    = (struct piece_closure *) value_computed_closure (value);
-  int i;
-
-  bit_offset += 8 * value_offset (value);
-  if (value_bitsize (value))
-    bit_offset += value_bitpos (value);
-
-  for (i = 0; i < c->pieces.size () && bit_length > 0; i++)
-    {
-      struct dwarf_expr_piece *p = &c->pieces[i];
-      size_t this_size_bits = p->size;
-
-      if (bit_offset > 0)
-	{
-	  if (bit_offset >= this_size_bits)
-	    {
-	      bit_offset -= this_size_bits;
-	      continue;
-	    }
-
-	  bit_length -= this_size_bits - bit_offset;
-	  bit_offset = 0;
-	}
-      else
-	bit_length -= this_size_bits;
-
-      if (p->location != DWARF_VALUE_IMPLICIT_POINTER)
-	return 0;
-    }
-
-  return 1;
-}
-
-/* An implementation of an lval_funcs method to indirect through a
-   pointer.  This handles the synthetic pointer case when needed.  */
-
-static struct value *
-indirect_pieced_value (struct value *value)
-{
-  struct piece_closure *c
-    = (struct piece_closure *) value_computed_closure (value);
-  struct type *type;
-  struct frame_info *frame;
-  int i, bit_length;
-  LONGEST bit_offset;
-  struct dwarf_expr_piece *piece = NULL;
-  LONGEST byte_offset;
-  enum bfd_endian byte_order;
-
-  type = check_typedef (value_type (value));
-  if (type->code () != TYPE_CODE_PTR)
-    return NULL;
-
-  bit_length = 8 * TYPE_LENGTH (type);
-  bit_offset = 8 * value_offset (value);
-  if (value_bitsize (value))
-    bit_offset += value_bitpos (value);
-
-  for (i = 0; i < c->pieces.size () && bit_length > 0; i++)
-    {
-      struct dwarf_expr_piece *p = &c->pieces[i];
-      size_t this_size_bits = p->size;
-
-      if (bit_offset > 0)
-	{
-	  if (bit_offset >= this_size_bits)
-	    {
-	      bit_offset -= this_size_bits;
-	      continue;
-	    }
-
-	  bit_length -= this_size_bits - bit_offset;
-	  bit_offset = 0;
-	}
-      else
-	bit_length -= this_size_bits;
-
-      if (p->location != DWARF_VALUE_IMPLICIT_POINTER)
-	return NULL;
-
-      if (bit_length != 0)
-	error (_("Invalid use of DW_OP_implicit_pointer"));
-
-      piece = p;
-      break;
-    }
-
-  gdb_assert (piece != NULL && c->per_cu != nullptr);
-  frame = get_selected_frame (_("No frame selected."));
-
-  /* This is an offset requested by GDB, such as value subscripts.
-     However, due to how synthetic pointers are implemented, this is
-     always presented to us as a pointer type.  This means we have to
-     sign-extend it manually as appropriate.  Use raw
-     extract_signed_integer directly rather than value_as_address and
-     sign extend afterwards on architectures that would need it
-     (mostly everywhere except MIPS, which has signed addresses) as
-     the later would go through gdbarch_pointer_to_address and thus
-     return a CORE_ADDR with high bits set on architectures that
-     encode address spaces and other things in CORE_ADDR.  */
-  byte_order = gdbarch_byte_order (get_frame_arch (frame));
-  byte_offset = extract_signed_integer (value_contents (value),
-					TYPE_LENGTH (type), byte_order);
-  byte_offset += piece->v.ptr.offset;
-
-  return indirect_synthetic_pointer (piece->v.ptr.die_sect_off,
-				     byte_offset, c->per_cu,
-				     c->per_objfile, frame, type);
-}
-
-/* Implementation of the coerce_ref method of lval_funcs for synthetic C++
-   references.  */
-
-static struct value *
-coerce_pieced_ref (const struct value *value)
-{
-  struct type *type = check_typedef (value_type (value));
-
-  if (value_bits_synthetic_pointer (value, value_embedded_offset (value),
-				    TARGET_CHAR_BIT * TYPE_LENGTH (type)))
-    {
-      const struct piece_closure *closure
-	= (struct piece_closure *) value_computed_closure (value);
-      struct frame_info *frame
-	= get_selected_frame (_("No frame selected."));
-
-      /* gdb represents synthetic pointers as pieced values with a single
-	 piece.  */
-      gdb_assert (closure != NULL);
-      gdb_assert (closure->pieces.size () == 1);
-
-      return indirect_synthetic_pointer
-	(closure->pieces[0].v.ptr.die_sect_off,
-	 closure->pieces[0].v.ptr.offset,
-	 closure->per_cu, closure->per_objfile, frame, type);
-    }
-  else
-    {
-      /* Else: not a synthetic reference; do nothing.  */
-      return NULL;
-    }
-}
-
-static void *
-copy_pieced_value_closure (const struct value *v)
-{
-  struct piece_closure *c
-    = (struct piece_closure *) value_computed_closure (v);
-
-  ++c->refc;
-  return c;
-}
-
-static void
-free_pieced_value_closure (struct value *v)
-{
-  struct piece_closure *c
-    = (struct piece_closure *) value_computed_closure (v);
-
-  --c->refc;
-  if (c->refc == 0)
-    {
-      for (dwarf_expr_piece &p : c->pieces)
-	if (p.location == DWARF_VALUE_STACK)
-	  value_decref (p.v.value);
-
-      delete c;
-    }
-}
-
-/* Functions for accessing a variable described by DW_OP_piece.  */
-static const struct lval_funcs pieced_value_funcs = {
-  read_pieced_value,
-  write_pieced_value,
-  indirect_pieced_value,
-  coerce_pieced_ref,
-  check_pieced_synthetic_pointer,
-  copy_pieced_value_closure,
-  free_pieced_value_closure
-};
-
 /* Given context CTX, section offset SECT_OFF, and compilation unit
    data PER_CU, execute the "variable value" operation on the DIE
    found at SECT_OFF.  */
diff --git a/gdb/dwarf2/expr.h b/gdb/dwarf2/expr.h
index 2d24f4402db..3c404d8f83c 100644
--- a/gdb/dwarf2/expr.h
+++ b/gdb/dwarf2/expr.h
@@ -28,78 +28,6 @@
 class dwarf_entry;
 struct dwarf2_per_objfile;
 
-/* The location of a value.  */
-enum dwarf_value_location
-{
-  /* The piece is in memory.
-     The value on the dwarf stack is its address.  */
-  DWARF_VALUE_MEMORY,
-
-  /* The piece is in a register.
-     The value on the dwarf stack is the register number.  */
-  DWARF_VALUE_REGISTER,
-
-  /* The piece is on the dwarf stack.  */
-  DWARF_VALUE_STACK,
-
-  /* The piece is a literal.  */
-  DWARF_VALUE_LITERAL,
-
-  /* The piece was optimized out.  */
-  DWARF_VALUE_OPTIMIZED_OUT,
-
-  /* The piece is an implicit pointer.  */
-  DWARF_VALUE_IMPLICIT_POINTER
-};
-
-/* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece.  */
-struct dwarf_expr_piece
-{
-  enum dwarf_value_location location;
-
-  union
-  {
-    struct
-    {
-      /* This piece's address, for DWARF_VALUE_MEMORY pieces.  */
-      CORE_ADDR addr;
-      /* Non-zero if the piece is known to be in memory and on
-	 the program's stack.  */
-      bool in_stack_memory;
-    } mem;
-
-    /* The piece's register number, for DWARF_VALUE_REGISTER pieces.  */
-    int regno;
-
-    /* The piece's literal value, for DWARF_VALUE_STACK pieces.  */
-    struct value *value;
-
-    struct
-    {
-      /* A pointer to the data making up this piece,
-	 for DWARF_VALUE_LITERAL pieces.  */
-      const gdb_byte *data;
-      /* The length of the available data.  */
-      ULONGEST length;
-    } literal;
-
-    /* Used for DWARF_VALUE_IMPLICIT_POINTER.  */
-    struct
-    {
-      /* The referent DIE from DW_OP_implicit_pointer.  */
-      sect_offset die_sect_off;
-      /* The byte offset into the resulting data.  */
-      LONGEST offset;
-    } ptr;
-  } v;
-
-  /* The length of the piece, in bits.  */
-  ULONGEST size;
-  /* The piece offset, in bits.  */
-  ULONGEST offset;
-};
-
-
 /* The expression evaluator works with a dwarf_expr_context, describing
    its current state and its callbacks.  */
 struct dwarf_expr_context
-- 
2.17.1