gdb

* dwarf2loc.c (extract_bits_primitive): New function.
	(extract_bits): Likewise.
	(insert_bits): Likewise.
	(copy_bitwise): Likewise.
	(read_pieced_value): Do all operations in bits.
	(write_pieced_value): Likewise.
	* dwarf2expr.h (struct dwarf_expr_piece) <offset>: New field.
	* dwarf2expr.c (add_piece): New arguments bit_piece, offset.
	Always use xrealloc to resize piece array.
	(execute_stack_op) <DW_OP_reg0>: Handle DW_OP_bit_piece.
	<DW_OP_piece>: Update.
	<DW_OP_bit_piece>: New case.
gdb/testsuite
	* gdb.dwarf2/pieces.exp (pieces_test_f3): New proc.
	Call it.
	* gdb.dwarf2/pieces.S: Update.
	* gdb.dwarf2/pieces.c (struct B): Remove initial field.

gdb/ChangeLog

@@ -1,3 +1,18 @@
+2010-05-21  Tom Tromey  <tromey@redhat.com>
+
+	* dwarf2loc.c (extract_bits_primitive): New function.
+	(extract_bits): Likewise.
+	(insert_bits): Likewise.
+	(copy_bitwise): Likewise.
+	(read_pieced_value): Do all operations in bits.
+	(write_pieced_value): Likewise.
+	* dwarf2expr.h (struct dwarf_expr_piece) <offset>: New field.
+	* dwarf2expr.c (add_piece): New arguments bit_piece, offset.
+	Always use xrealloc to resize piece array.
+	(execute_stack_op) <DW_OP_reg0>: Handle DW_OP_bit_piece.
+	<DW_OP_piece>: Update.
+	<DW_OP_bit_piece>: New case.
+
 2010-05-21  Tom Tromey  <tromey@redhat.com>
 
 	* dwarf2loc.c (read_pieced_value): Exit loop when result is full.

gdb/dwarf2expr.c

@@ -153,23 +153,21 @@ dwarf_expr_stack_empty_p (struct dwarf_expr_context *ctx)
 
 /* Add a new piece to CTX's piece list.  */
 static void
-add_piece (struct dwarf_expr_context *ctx, ULONGEST size)
+add_piece (struct dwarf_expr_context *ctx, ULONGEST size, ULONGEST offset)
 {
   struct dwarf_expr_piece *p;
 
   ctx->num_pieces++;
 
-  if (ctx->pieces)
+  ctx->pieces = xrealloc (ctx->pieces,
-    ctx->pieces = xrealloc (ctx->pieces,
+			  (ctx->num_pieces
-                            (ctx->num_pieces
+			   * sizeof (struct dwarf_expr_piece)));
-                             * sizeof (struct dwarf_expr_piece)));
-  else
-    ctx->pieces = xmalloc (ctx->num_pieces
-                           * sizeof (struct dwarf_expr_piece));
 
   p = &ctx->pieces[ctx->num_pieces - 1];
   p->location = ctx->location;
   p->size = size;
+  p->offset = offset;
+
   if (p->location == DWARF_VALUE_LITERAL)
     {
       p->v.literal.data = ctx->data;
@@ -499,9 +497,11 @@ execute_stack_op (struct dwarf_expr_context *ctx,
 	case DW_OP_reg31:
 	  if (op_ptr != op_end 
 	      && *op_ptr != DW_OP_piece
+	      && *op_ptr != DW_OP_bit_piece
 	      && *op_ptr != DW_OP_GNU_uninit)
 	    error (_("DWARF-2 expression error: DW_OP_reg operations must be "
-		   "used either alone or in conjuction with DW_OP_piece."));
+		     "used either alone or in conjuction with DW_OP_piece "
+		     "or DW_OP_bit_piece."));
 
 	  result = op - DW_OP_reg0;
 	  ctx->location = DWARF_VALUE_REGISTER;
@@ -872,7 +872,7 @@ execute_stack_op (struct dwarf_expr_context *ctx,
 
             /* Record the piece.  */
             op_ptr = read_uleb128 (op_ptr, op_end, &size);
-	    add_piece (ctx, size);
+	    add_piece (ctx, 8 * size, 0);
 
             /* Pop off the address/regnum, and reset the location
 	       type.  */
@@ -883,6 +883,24 @@ execute_stack_op (struct dwarf_expr_context *ctx,
           }
           goto no_push;
 
+	case DW_OP_bit_piece:
+	  {
+	    ULONGEST size, offset;
+
+            /* Record the piece.  */
+	    op_ptr = read_uleb128 (op_ptr, op_end, &size);
+	    op_ptr = read_uleb128 (op_ptr, op_end, &offset);
+	    add_piece (ctx, size, offset);
+
+            /* Pop off the address/regnum, and reset the location
+	       type.  */
+	    if (ctx->location != DWARF_VALUE_LITERAL
+		&& ctx->location != DWARF_VALUE_OPTIMIZED_OUT)
+	      dwarf_expr_pop (ctx);
+            ctx->location = DWARF_VALUE_MEMORY;
+	  }
+	  goto no_push;
+
 	case DW_OP_GNU_uninit:
 	  if (op_ptr != op_end)
 	    error (_("DWARF-2 expression error: DW_OP_GNU_uninit must always "

gdb/dwarf2expr.h

@@ -155,7 +155,7 @@ struct dwarf_expr_context
 };
 
 
-/* A piece of an object, as recorded by DW_OP_piece.  */
+/* 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;
@@ -181,8 +181,10 @@ struct dwarf_expr_piece
     } literal;
   } v;
 
-  /* The length of the piece, in bytes.  */
+  /* The length of the piece, in bits.  */
   ULONGEST size;
+  /* The piece offset, in bits.  */
+  ULONGEST offset;
 };
 
 struct dwarf_expr_context *new_dwarf_expr_context (void);

gdb/dwarf2loc.c

@@ -259,52 +259,245 @@ allocate_piece_closure (int n_pieces, struct dwarf_expr_piece *pieces,
   return c;
 }
 
+/* The lowest-level function to extract bits from a byte buffer.
+   SOURCE is the buffer.  It is updated if we read to the end of a
+   byte.
+   SOURCE_OFFSET_BITS is the offset of the first bit to read.  It is
+   updated to reflect the number of bits actually read.
+   NBITS is the number of bits we want to read.  It is updated to
+   reflect the number of bits actually read.  This function may read
+   fewer bits.
+   BITS_BIG_ENDIAN is taken directly from gdbarch.
+   This function returns the extracted bits.  */
+
+static unsigned int
+extract_bits_primitive (const gdb_byte **source,
+			unsigned int *source_offset_bits,
+			int *nbits, int bits_big_endian)
+{
+  unsigned int avail, mask, datum;
+
+  gdb_assert (*source_offset_bits < 8);
+
+  avail = 8 - *source_offset_bits;
+  if (avail > *nbits)
+    avail = *nbits;
+
+  mask = (1 << avail) - 1;
+  datum = **source;
+  if (bits_big_endian)
+    datum >>= 8 - (*source_offset_bits + *nbits);
+  else
+    datum >>= *source_offset_bits;
+  datum &= mask;
+
+  *nbits -= avail;
+  *source_offset_bits += avail;
+  if (*source_offset_bits >= 8)
+    {
+      *source_offset_bits -= 8;
+      ++*source;
+    }
+
+  return datum;
+}
+
+/* Extract some bits from a source buffer and move forward in the
+   buffer.
+   
+   SOURCE is the source buffer.  It is updated as bytes are read.
+   SOURCE_OFFSET_BITS is the offset into SOURCE.  It is updated as
+   bits are read.
+   NBITS is the number of bits to read.
+   BITS_BIG_ENDIAN is taken directly from gdbarch.
+   
+   This function returns the bits that were read.  */
+
+static unsigned int
+extract_bits (const gdb_byte **source, unsigned int *source_offset_bits,
+	      int nbits, int bits_big_endian)
+{
+  unsigned int datum;
+
+  gdb_assert (nbits > 0 && nbits <= 8);
+
+  datum = extract_bits_primitive (source, source_offset_bits, &nbits,
+				  bits_big_endian);
+  if (nbits > 0)
+    {
+      unsigned int more;
+
+      more = extract_bits_primitive (source, source_offset_bits, &nbits,
+				     bits_big_endian);
+      if (bits_big_endian)
+	datum <<= nbits;
+      else
+	more <<= nbits;
+      datum |= more;
+    }
+
+  return datum;
+}
+
+/* Write some bits into a buffer and move forward in the buffer.
+   
+   DATUM is the bits to write.  The low-order bits of DATUM are used.
+   DEST is the destination buffer.  It is updated as bytes are
+   written.
+   DEST_OFFSET_BITS is the bit offset in DEST at which writing is
+   done.
+   NBITS is the number of valid bits in DATUM.
+   BITS_BIG_ENDIAN is taken directly from gdbarch.  */
+
+static void
+insert_bits (unsigned int datum,
+	     gdb_byte *dest, unsigned int dest_offset_bits,
+	     int nbits, int bits_big_endian)
+{
+  unsigned int mask;
+
+  gdb_assert (dest_offset_bits >= 0 && dest_offset_bits + nbits <= 8);
+
+  mask = (1 << nbits) - 1;
+  if (bits_big_endian)
+    {
+      datum <<= 8 - (dest_offset_bits + nbits);
+      mask <<= 8 - (dest_offset_bits + nbits);
+    }
+  else
+    {
+      datum <<= dest_offset_bits;
+      mask <<= dest_offset_bits;
+    }
+
+  gdb_assert ((datum & ~mask) == 0);
+
+  *dest = (*dest & ~mask) | datum;
+}
+
+/* Copy bits from a source to a destination.
+   
+   DEST is where the bits should be written.
+   DEST_OFFSET_BITS is the bit offset into DEST.
+   SOURCE is the source of bits.
+   SOURCE_OFFSET_BITS is the bit offset into SOURCE.
+   BIT_COUNT is the number of bits to copy.
+   BITS_BIG_ENDIAN is taken directly from gdbarch.  */
+
+static void
+copy_bitwise (gdb_byte *dest, unsigned int dest_offset_bits,
+	      const gdb_byte *source, unsigned int source_offset_bits,
+	      unsigned int bit_count,
+	      int bits_big_endian)
+{
+  unsigned int dest_avail;
+  int datum;
+
+  /* Reduce everything to byte-size pieces.  */
+  dest += dest_offset_bits / 8;
+  dest_offset_bits %= 8;
+  source += source_offset_bits / 8;
+  source_offset_bits %= 8;
+
+  dest_avail = 8 - dest_offset_bits % 8;
+
+  /* See if we can fill the first destination byte.  */
+  if (dest_avail < bit_count)
+    {
+      datum = extract_bits (&source, &source_offset_bits, dest_avail,
+			    bits_big_endian);
+      insert_bits (datum, dest, dest_offset_bits, dest_avail, bits_big_endian);
+      ++dest;
+      dest_offset_bits = 0;
+      bit_count -= dest_avail;
+    }
+
+  /* Now, either DEST_OFFSET_BITS is byte-aligned, or we have fewer
+     than 8 bits remaining.  */
+  gdb_assert (dest_offset_bits % 8 == 0 || bit_count < 8);
+  for (; bit_count >= 8; bit_count -= 8)
+    {
+      datum = extract_bits (&source, &source_offset_bits, 8, bits_big_endian);
+      *dest++ = (gdb_byte) datum;
+    }
+
+  /* Finally, we may have a few leftover bits.  */
+  gdb_assert (bit_count <= 8 - dest_offset_bits % 8);
+  if (bit_count > 0)
+    {
+      datum = extract_bits (&source, &source_offset_bits, bit_count,
+			    bits_big_endian);
+      insert_bits (datum, dest, dest_offset_bits, bit_count, bits_big_endian);
+    }
+}
+
 static void
 read_pieced_value (struct value *v)
 {
   int i;
   long offset = 0;
-  ULONGEST bytes_to_skip;
+  ULONGEST bits_to_skip;
   gdb_byte *contents;
   struct piece_closure *c = (struct piece_closure *) value_computed_closure (v);
   struct frame_info *frame = frame_find_by_id (VALUE_FRAME_ID (v));
   size_t type_len;
+  size_t buffer_size = 0;
+  char *buffer = NULL;
+  struct cleanup *cleanup;
+  int bits_big_endian
+    = gdbarch_bits_big_endian (get_type_arch (value_type (v)));
 
   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"));
 
+  cleanup = make_cleanup (free_current_contents, &buffer);
+
   contents = value_contents_raw (v);
-  bytes_to_skip = value_offset (v);
+  bits_to_skip = 8 * value_offset (v);
-  type_len = TYPE_LENGTH (value_type (v));
+  type_len = 8 * TYPE_LENGTH (value_type (v));
+
   for (i = 0; i < c->n_pieces && offset < type_len; i++)
     {
       struct dwarf_expr_piece *p = &c->pieces[i];
-      size_t this_size;
+      size_t this_size, this_size_bits;
-      long dest_offset, source_offset;
+      long dest_offset_bits, source_offset_bits, source_offset;
+      gdb_byte *intermediate_buffer;
 
-      if (bytes_to_skip > 0 && bytes_to_skip >= p->size)
+      /* Compute size, source, and destination offsets for copying, in
+	 bits.  */
+      this_size_bits = p->size;
+      if (bits_to_skip > 0 && bits_to_skip >= this_size_bits)
 	{
-	  bytes_to_skip -= p->size;
+	  bits_to_skip -= this_size_bits;
 	  continue;
 	}
-      this_size = p->size;
+      if (this_size_bits > type_len - offset)
-      if (this_size > type_len - offset)
+	this_size_bits = type_len - offset;
-	this_size = type_len - offset;
+      if (bits_to_skip > 0)
-      if (bytes_to_skip > 0)
 	{
-	  dest_offset = 0;
+	  dest_offset_bits = 0;
-	  source_offset = bytes_to_skip;
+	  source_offset_bits = bits_to_skip;
-	  this_size -= bytes_to_skip;
+	  this_size_bits -= bits_to_skip;
-	  bytes_to_skip = 0;
+	  bits_to_skip = 0;
 	}
       else
 	{
-	  dest_offset = offset;
+	  dest_offset_bits = offset;
-	  source_offset = 0;
+	  source_offset_bits = 0;
 	}
 
+      this_size = (this_size_bits + source_offset_bits % 8 + 7) / 8;
+      source_offset = source_offset_bits / 8;
+      if (buffer_size < this_size)
+	{
+	  buffer_size = this_size;
+	  buffer = xrealloc (buffer, buffer_size);
+	}
+      intermediate_buffer = buffer;
+
+      /* Copy from the source to DEST_BUFFER.  */
       switch (p->location)
 	{
 	case DWARF_VALUE_REGISTER:
@@ -316,13 +509,18 @@ read_pieced_value (struct value *v)
 
 	    if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG
 		&& this_size < register_size (arch, gdb_regnum))
-	      /* Big-endian, and we want less than full size.  */
+	      {
-	      reg_offset = register_size (arch, gdb_regnum) - this_size;
+		/* Big-endian, and we want less than full size.  */
+		reg_offset = register_size (arch, gdb_regnum) - this_size;
+		/* We want the lower-order THIS_SIZE_BITS of the bytes
+		   we extract from the register.  */
+		source_offset_bits += 8 * this_size - this_size_bits;
+	      }
 
 	    if (gdb_regnum != -1)
 	      {
 		get_frame_register_bytes (frame, gdb_regnum, reg_offset, 
-					  this_size, contents + dest_offset);
+					  this_size, buffer);
 	      }
 	    else
 	      {
@@ -334,11 +532,9 @@ read_pieced_value (struct value *v)
 
 	case DWARF_VALUE_MEMORY:
 	  if (p->v.expr.in_stack_memory)
-	    read_stack (p->v.expr.value + source_offset,
+	    read_stack (p->v.expr.value + source_offset, buffer, this_size);
-			contents + dest_offset, this_size);
 	  else
-	    read_memory (p->v.expr.value + source_offset,
+	    read_memory (p->v.expr.value + source_offset, buffer, this_size);
-			 contents + dest_offset, this_size);
 	  break;
 
 	case DWARF_VALUE_STACK:
@@ -355,7 +551,7 @@ read_pieced_value (struct value *v)
 		/* Nothing.  */
 	      }
 	    else if (source_offset == 0)
-	      store_unsigned_integer (contents + dest_offset, n,
+	      store_unsigned_integer (buffer, n,
 				      gdbarch_byte_order (gdbarch),
 				      p->v.expr.value);
 	    else
@@ -365,7 +561,7 @@ read_pieced_value (struct value *v)
 		store_unsigned_integer (bytes, n + source_offset,
 					gdbarch_byte_order (gdbarch),
 					p->v.expr.value);
-		memcpy (contents + dest_offset, bytes + source_offset, n);
+		memcpy (buffer, bytes + source_offset, n);
 	      }
 	  }
 	  break;
@@ -379,8 +575,7 @@ read_pieced_value (struct value *v)
 		   ? p->v.literal.length - source_offset
 		   : 0);
 	    if (n != 0)
-	      memcpy (contents + dest_offset,
+	      intermediate_buffer = p->v.literal.data + source_offset;
-		      p->v.literal.data + source_offset, n);
 	  }
 	  break;
 
@@ -388,17 +583,25 @@ read_pieced_value (struct value *v)
 	  /* We just leave the bits empty for now.  This is not ideal
 	     but gdb currently does not have a nice way to represent
 	     optimized-out pieces.  */
-	  warning (_("bytes %ld-%ld in computed object were optimized out; "
+	  warning (_("bits %ld-%ld in computed object were optimized out; "
 		     "replacing with zeroes"),
 		   offset,
-		   offset + (long) this_size);
+		   offset + (long) this_size_bits);
 	  break;
 
 	default:
 	  internal_error (__FILE__, __LINE__, _("invalid location type"));
 	}
-      offset += this_size;
+
+      if (p->location != DWARF_VALUE_OPTIMIZED_OUT)
+	copy_bitwise (contents, dest_offset_bits,
+		      intermediate_buffer, source_offset_bits % 8,
+		      this_size_bits, bits_big_endian);
+
+      offset += this_size_bits;
     }
+
+  do_cleanups (cleanup);
 }
 
 static void
@@ -406,11 +609,16 @@ write_pieced_value (struct value *to, struct value *from)
 {
   int i;
   long offset = 0;
-  ULONGEST bytes_to_skip;
+  ULONGEST bits_to_skip;
   const gdb_byte *contents;
   struct piece_closure *c = (struct piece_closure *) value_computed_closure (to);
   struct frame_info *frame = frame_find_by_id (VALUE_FRAME_ID (to));
   size_t type_len;
+  size_t buffer_size = 0;
+  char *buffer = NULL;
+  struct cleanup *cleanup;
+  int bits_big_endian
+    = gdbarch_bits_big_endian (get_type_arch (value_type (to)));
 
   if (frame == NULL)
     {
@@ -418,34 +626,57 @@ write_pieced_value (struct value *to, struct value *from)
       return;
     }
 
+  cleanup = make_cleanup (free_current_contents, &buffer);
+
   contents = value_contents (from);
-  bytes_to_skip = value_offset (to);
+  bits_to_skip = 8 * value_offset (to);
-  type_len = TYPE_LENGTH (value_type (to));
+  type_len = 8 * TYPE_LENGTH (value_type (to));
   for (i = 0; i < c->n_pieces && offset < type_len; i++)
     {
       struct dwarf_expr_piece *p = &c->pieces[i];
-      size_t this_size;
+      size_t this_size_bits, this_size;
-      long dest_offset, source_offset;
+      long dest_offset_bits, source_offset_bits, dest_offset, source_offset;
+      int need_bitwise;
+      const gdb_byte *source_buffer;
 
-      if (bytes_to_skip > 0 && bytes_to_skip >= p->size)
+      this_size_bits = p->size;
+      if (bits_to_skip > 0 && bits_to_skip >= this_size_bits)
 	{
-	  bytes_to_skip -= p->size;
+	  bits_to_skip -= this_size_bits;
 	  continue;
 	}
-      this_size = p->size;
+      if (this_size_bits > type_len - offset)
-      if (this_size > type_len - offset)
+	this_size_bits = type_len - offset;
-	this_size = type_len - offset;
+      if (bits_to_skip > 0)
-      if (bytes_to_skip > 0)
 	{
-	  dest_offset = bytes_to_skip;
+	  dest_offset_bits = bits_to_skip;
-	  source_offset = 0;
+	  source_offset_bits = 0;
-	  this_size -= bytes_to_skip;
+	  this_size_bits -= bits_to_skip;
-	  bytes_to_skip = 0;
+	  bits_to_skip = 0;
 	}
       else
 	{
-	  dest_offset = 0;
+	  dest_offset_bits = 0;
-	  source_offset = offset;
+	  source_offset_bits = offset;
+	}
+
+      this_size = (this_size_bits + source_offset_bits % 8 + 7) / 8;
+      source_offset = source_offset_bits / 8;
+      dest_offset = dest_offset_bits / 8;
+      if (dest_offset_bits % 8 == 0 && source_offset_bits % 8 == 0)
+	{
+	  source_buffer = contents + source_offset;
+	  need_bitwise = 0;
+	}
+      else
+	{
+	  if (buffer_size < this_size)
+	    {
+	      buffer_size = this_size;
+	      buffer = xrealloc (buffer, buffer_size);
+	    }
+	  source_buffer = buffer;
+	  need_bitwise = 1;
 	}
 
       switch (p->location)
@@ -463,8 +694,18 @@ write_pieced_value (struct value *to, struct value *from)
 
 	    if (gdb_regnum != -1)
 	      {
+		if (need_bitwise)
+		  {
+		    get_frame_register_bytes (frame, gdb_regnum, reg_offset,
+					      this_size, buffer);
+		    copy_bitwise (buffer, dest_offset_bits,
+				  contents, source_offset_bits,
+				  this_size_bits,
+				  bits_big_endian);
+		  }
+
 		put_frame_register_bytes (frame, gdb_regnum, reg_offset, 
-					  this_size, contents + source_offset);
+					  this_size, source_buffer);
 	      }
 	    else
 	      {
@@ -474,15 +715,31 @@ write_pieced_value (struct value *to, struct value *from)
 	  }
 	  break;
 	case DWARF_VALUE_MEMORY:
+	  if (need_bitwise)
+	    {
+	      /* Only the first and last bytes can possibly have any
+		 bits reused.  */
+	      read_memory (p->v.expr.value + dest_offset, buffer, 1);
+	      read_memory (p->v.expr.value + dest_offset + this_size - 1,
+			   buffer + this_size - 1, 1);
+	      copy_bitwise (buffer, dest_offset_bits,
+			    contents, source_offset_bits,
+			    this_size_bits,
+			    bits_big_endian);
+	    }
+
 	  write_memory (p->v.expr.value + dest_offset,
-			contents + source_offset, this_size);
+			source_buffer, this_size);
 	  break;
 	default:
 	  set_value_optimized_out (to, 1);
-	  return;
+	  goto done;
 	}
-      offset += this_size;
+      offset += this_size_bits;
     }
+
+ done:
+  do_cleanups (cleanup);
 }
 
 static void *

gdb/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2010-05-21  Tom Tromey  <tromey@redhat.com>
+
+	* gdb.dwarf2/pieces.exp (pieces_test_f3): New proc.
+	Call it.
+	* gdb.dwarf2/pieces.S: Update.
+	* gdb.dwarf2/pieces.c (struct B): Remove initial field.
+
 2010-05-21  Tom Tromey  <tromey@redhat.com>
 
 	* gdb.dwarf2/pieces.exp (pieces_test_f6): New proc.

gdb/testsuite/gdb.dwarf2/pieces.S

@@ -989,23 +989,18 @@ main:
 .LLST6:
 	.long	.LVL13-.Ltext0	# Location list begin address (*.LLST6)
 	.long	.LVL14-.Ltext0	# Location list end address (*.LLST6)
-	.value	0xa	# Location expression size
+	.value	0x8	# Location expression size
-	.byte	0x9d	# DW_OP_bit_piece
-	.uleb128 0x4
-	.uleb128 0
 	.byte	0x34	# DW_OP_lit4
 	.byte	0x9f	# DW_OP_stack_value
 	.byte	0x9d	# DW_OP_bit_piece
 	.uleb128 0xc
 	.uleb128 0
-	.byte	0x93	# DW_OP_piece
+	.byte	0x9d	# DW_OP_bit_piece
-	.uleb128 0x2
+	.uleb128 0x14
+	.uleb128 0
 	.long	.LVL14-.Ltext0	# Location list begin address (*.LLST6)
 	.long	.LVL15-.Ltext0	# Location list end address (*.LLST6)
-	.value	0x15	# Location expression size
+	.value	0x11	# Location expression size
-	.byte	0x9d	# DW_OP_bit_piece
-	.uleb128 0x4
-	.uleb128 0
 	.byte	0x34	# DW_OP_lit4
 	.byte	0x9f	# DW_OP_stack_value
 	.byte	0x9d	# DW_OP_bit_piece
@@ -1021,15 +1016,11 @@ main:
 	.byte	0x9d	# DW_OP_bit_piece
 	.uleb128 0xc
 	.uleb128 0
-	.byte	0x9d	# DW_OP_bit_piece
+	.byte	0x93	# DW_OP_piece
-	.uleb128 0x4
+	.uleb128 0x1
-	.uleb128 0
 	.long	.LVL15-.Ltext0	# Location list begin address (*.LLST6)
 	.long	.LVL16-1-.Ltext0	# Location list end address (*.LLST6)
-	.value	0x14	# Location expression size
+	.value	0x10	# Location expression size
-	.byte	0x9d	# DW_OP_bit_piece
-	.uleb128 0x4
-	.uleb128 0
 	.byte	0x52	# DW_OP_reg2
 	.byte	0x9d	# DW_OP_bit_piece
 	.uleb128 0xc
@@ -1044,15 +1035,11 @@ main:
 	.byte	0x9d	# DW_OP_bit_piece
 	.uleb128 0xc
 	.uleb128 0
-	.byte	0x9d	# DW_OP_bit_piece
+	.byte	0x93	# DW_OP_piece
-	.uleb128 0x4
+	.uleb128 0x1
-	.uleb128 0
 	.long	.LVL16-1-.Ltext0	# Location list begin address (*.LLST6)
 	.long	.LVL17-.Ltext0	# Location list end address (*.LLST6)
-	.value	0x14	# Location expression size
+	.value	0x10	# Location expression size
-	.byte	0x9d	# DW_OP_bit_piece
-	.uleb128 0x4
-	.uleb128 0
 	.byte	0x56	# DW_OP_reg6
 	.byte	0x9d	# DW_OP_bit_piece
 	.uleb128 0xc
@@ -1067,14 +1054,14 @@ main:
 	.byte	0x9d	# DW_OP_bit_piece
 	.uleb128 0xc
 	.uleb128 0
-	.byte	0x9d	# DW_OP_bit_piece
+	.byte	0x93	# DW_OP_piece
-	.uleb128 0x4
+	.uleb128 0x1
-	.uleb128 0
 	.long	.LVL17-.Ltext0	# Location list begin address (*.LLST6)
 	.long	.LFE3-.Ltext0	# Location list end address (*.LLST6)
 	.value	0xf	# Location expression size
-	.byte	0x93	# DW_OP_piece
+	.byte	0x9d	# DW_OP_bit_piece
-	.uleb128 0x2
+	.uleb128 0xc
+	.uleb128 0
 	.byte	0x91	# DW_OP_fbreg
 	.sleb128 0
 	.byte	0x94	# DW_OP_deref_size
@@ -1085,9 +1072,8 @@ main:
 	.byte	0x9d	# DW_OP_bit_piece
 	.uleb128 0xc
 	.uleb128 0
-	.byte	0x9d	# DW_OP_bit_piece
+	.byte	0x93	# DW_OP_piece
-	.uleb128 0x4
+	.uleb128 0x1
-	.uleb128 0
 	.long	0	# Location list terminator begin (*.LLST6)
 	.long	0	# Location list terminator end (*.LLST6)
 .LLST7:
@@ -1356,7 +1342,7 @@ main:
 	.long	0x48	# DW_AT_type
 	.byte	0x4	# DW_AT_byte_size
 	.byte	0xc	# DW_AT_bit_size
-	.byte	0x10	# DW_AT_bit_offset
+	.byte	0x14	# DW_AT_bit_offset
 	.byte	0x2	# DW_AT_data_member_location
 	.byte	0x23	# DW_OP_plus_uconst
 	.uleb128 0
@@ -1367,7 +1353,7 @@ main:
 	.long	0x48	# DW_AT_type
 	.byte	0x4	# DW_AT_byte_size
 	.byte	0xc	# DW_AT_bit_size
-	.byte	0x4	# DW_AT_bit_offset
+	.byte	0x8	# DW_AT_bit_offset
 	.byte	0x2	# DW_AT_data_member_location
 	.byte	0x23	# DW_OP_plus_uconst
 	.uleb128 0

gdb/testsuite/gdb.dwarf2/pieces.c

@@ -21,7 +21,7 @@
    However, it is used to extract breakpoint line numbers.  */
 
 struct A { int i; int j; };
-struct B { int : 4; int i : 12; int j : 12; int : 4; };
+struct B { int i : 12; int j : 12; int : 4; };
 struct C { int i; int j; int q; };
 
 __attribute__((noinline)) void
@@ -89,7 +89,7 @@ __attribute__((noinline)) int
 f6 (int k)
 {
   int z = 23;
-  struct C a = { k, k, z};
+  struct C a = { k, k, z };
   asm ("" : "+r" (a.i));
   a.j++;
   bar (a.i);

gdb/testsuite/gdb.dwarf2/pieces.exp

@@ -67,15 +67,30 @@ proc pieces_test_f2 {} {
     gdb_test "print a\[1\]" " = 14" "print a\[1\] in pieces:f2"
 }
 
+# Function f3 tests DW_OP_bit_piece.
+proc pieces_test_f3 {} {
+    global csrcfile
+    set line [gdb_get_line_number "f3 breakpoint" $csrcfile]
+    gdb_test "break pieces.c:$line" "Breakpoint 4.*" \
+       "set f3 breakpoint for pieces"
+    gdb_continue_to_breakpoint "continue to f3 breakpoint for pieces"
+    gdb_test "print a.i" " = 4" "print a.i in pieces:f3"
+    gdb_test "print a.j" " = 14" "print a.j in pieces:f3"
+    # Right now gdb says "value optimized out" here, but that is wrong.
+    setup_kfail "no bug yet" *-*-*
+    gdb_test "print a.i = 7" " = 7" "set a.i in pieces:f3"
+    gdb_test "print a.i" " = 7" "print new a.i in pieces:f3"
+}
+
 # Function f6 tests for an empty DW_OP_piece.
 proc pieces_test_f6 {} {
     global csrcfile
     set line [gdb_get_line_number "f6 breakpoint" $csrcfile]
-    gdb_test "break pieces.c:$line" "Breakpoint 4.*" \
+    gdb_test "break pieces.c:$line" "Breakpoint 5.*" \
        "set f6 breakpoint for pieces"
     gdb_continue_to_breakpoint "continue to f6 breakpoint for pieces"
     gdb_test "print a" \
-	"warning: bytes .* in computed object were.* = {i = 7, j = 8, q = 0}" \
+	"warning: bits .* in computed object were.* = {i = 7, j = 8, q = 0}" \
 	"print a with optimized out piece"
     # Note: no warning for this case.
     gdb_test_multiple "print a.i" \
@@ -91,4 +106,5 @@ proc pieces_test_f6 {} {
 
 pieces_test_f1
 pieces_test_f2
+pieces_test_f3
 pieces_test_f6