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Re: RFC: add DWARF-4 features
>>>>> "Jan" == Jan Kratochvil <jan.kratochvil@redhat.com> writes:
[...]
Jan> I would prefer unified form of the expressions as an aid to the
Jan> reader. Here is MINIMUM_INSTRUCTION_LENGTH preceding the rest of
Jan> the expression while it is succeeding the rest of the expression in
Jan> the patch chunk above.
Thanks for your excellent review.
I am committing the appended updated patch.
Tom
2010-04-20 Tom Tromey <tromey@redhat.com>
* dwarf2-frame.c (decode_frame_entry_1): Handle CIE version 4.
(struct dwarf2_cie) <segment_size>: New field.
* dwarf2read.c (partial_read_comp_unit_head): Accept DWARF 4.
(skip_one_die): Handle DW_FORM_flag_present, DW_FORM_sec_offset,
DW_FORM_exprloc.
(read_attribute_value): Handle DW_FORM_flag_present,
DW_FORM_sec_offset, DW_FORM_exprloc.
(dump_die_shallow): Likewise.
(attr_form_is_section_offset): Handle DW_FORM_sec_offset.
(dwarf2_const_value): Handle DW_FORM_exprloc.
(attr_form_is_block): Likewise.
(struct line_header) <maximum_ops_per_instruction>: New field.
(dwarf_decode_line_header): Set new field.
(dwarf_decode_lines): Handle new field.
Index: dwarf2-frame.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2-frame.c,v
retrieving revision 1.107
diff -u -r1.107 dwarf2-frame.c
--- dwarf2-frame.c 24 Mar 2010 21:06:30 -0000 1.107
+++ dwarf2-frame.c 20 Apr 2010 17:32:08 -0000
@@ -85,6 +85,9 @@
/* The version recorded in the CIE. */
unsigned char version;
+
+ /* The segment size. */
+ unsigned char segment_size;
};
struct dwarf2_cie_table
@@ -1714,7 +1717,7 @@
/* Check version number. */
cie_version = read_1_byte (unit->abfd, buf);
- if (cie_version != 1 && cie_version != 3)
+ if (cie_version != 1 && cie_version != 3 && cie_version != 4)
return NULL;
cie->version = cie_version;
buf += 1;
@@ -1738,6 +1741,20 @@
augmentation += 2;
}
+ if (cie->version >= 4)
+ {
+ /* FIXME: check that this is the same as from the CU header. */
+ cie->addr_size = read_1_byte (unit->abfd, buf);
+ ++buf;
+ cie->segment_size = read_1_byte (unit->abfd, buf);
+ ++buf;
+ }
+ else
+ {
+ cie->addr_size = gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT;
+ cie->segment_size = 0;
+ }
+
cie->code_alignment_factor =
read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
buf += bytes_read;
Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.378
diff -u -r1.378 dwarf2read.c
--- dwarf2read.c 2 Apr 2010 15:21:47 -0000 1.378
+++ dwarf2read.c 20 Apr 2010 17:32:09 -0000
@@ -396,6 +396,7 @@
unsigned short version;
unsigned int header_length;
unsigned char minimum_instruction_length;
+ unsigned char maximum_ops_per_instruction;
unsigned char default_is_stmt;
int line_base;
unsigned char line_range;
@@ -1488,10 +1489,10 @@
info_ptr = read_comp_unit_head (header, info_ptr, abfd);
- if (header->version != 2 && header->version != 3)
+ if (header->version != 2 && header->version != 3 && header->version != 4)
error (_("Dwarf Error: wrong version in compilation unit header "
- "(is %d, should be %d) [in module %s]"), header->version,
- 2, bfd_get_filename (abfd));
+ "(is %d, should be 2, 3, or 4) [in module %s]"), header->version,
+ bfd_get_filename (abfd));
if (header->abbrev_offset >= dwarf2_per_objfile->abbrev.size)
error (_("Dwarf Error: bad offset (0x%lx) in compilation unit header "
@@ -2776,6 +2777,8 @@
case DW_FORM_flag:
info_ptr += 1;
break;
+ case DW_FORM_flag_present:
+ break;
case DW_FORM_data2:
case DW_FORM_ref2:
info_ptr += 2;
@@ -2793,9 +2796,11 @@
read_string (abfd, info_ptr, &bytes_read);
info_ptr += bytes_read;
break;
+ case DW_FORM_sec_offset:
case DW_FORM_strp:
info_ptr += cu->header.offset_size;
break;
+ case DW_FORM_exprloc:
case DW_FORM_block:
info_ptr += read_unsigned_leb128 (abfd, info_ptr, &bytes_read);
info_ptr += bytes_read;
@@ -7129,6 +7134,10 @@
DW_UNSND (attr) = read_8_bytes (abfd, info_ptr);
info_ptr += 8;
break;
+ case DW_FORM_sec_offset:
+ DW_UNSND (attr) = read_offset (abfd, info_ptr, &cu->header, &bytes_read);
+ info_ptr += bytes_read;
+ break;
case DW_FORM_string:
DW_STRING (attr) = read_string (abfd, info_ptr, &bytes_read);
DW_STRING_IS_CANONICAL (attr) = 0;
@@ -7140,6 +7149,7 @@
DW_STRING_IS_CANONICAL (attr) = 0;
info_ptr += bytes_read;
break;
+ case DW_FORM_exprloc:
case DW_FORM_block:
blk = dwarf_alloc_block (cu);
blk->size = read_unsigned_leb128 (abfd, info_ptr, &bytes_read);
@@ -7164,6 +7174,9 @@
DW_UNSND (attr) = read_1_byte (abfd, info_ptr);
info_ptr += 1;
break;
+ case DW_FORM_flag_present:
+ DW_UNSND (attr) = 1;
+ break;
case DW_FORM_sdata:
DW_SND (attr) = read_signed_leb128 (abfd, info_ptr, &bytes_read);
info_ptr += bytes_read;
@@ -7680,7 +7693,7 @@
/* Return non-zero iff the attribute NAME is defined for the given DIE,
and holds a non-zero value. This function should only be used for
- DW_FORM_flag attributes. */
+ DW_FORM_flag or DW_FORM_flag_present attributes. */
static int
dwarf2_flag_true_p (struct die_info *die, unsigned name, struct dwarf2_cu *cu)
@@ -7862,6 +7875,21 @@
line_ptr += offset_size;
lh->minimum_instruction_length = read_1_byte (abfd, line_ptr);
line_ptr += 1;
+ if (lh->version >= 4)
+ {
+ lh->maximum_ops_per_instruction = read_1_byte (abfd, line_ptr);
+ line_ptr += 1;
+ }
+ else
+ lh->maximum_ops_per_instruction = 1;
+
+ if (lh->maximum_ops_per_instruction == 0)
+ {
+ lh->maximum_ops_per_instruction = 1;
+ complaint (&symfile_complaints,
+ _("invalid maximum_ops_per_instruction in `.debug_line' section"));
+ }
+
lh->default_is_stmt = read_1_byte (abfd, line_ptr);
line_ptr += 1;
lh->line_base = read_1_signed_byte (abfd, line_ptr);
@@ -8010,6 +8038,7 @@
int basic_block = 0;
int end_sequence = 0;
CORE_ADDR addr;
+ unsigned char op_index = 0;
if (!decode_for_pst_p && lh->num_file_names >= file)
{
@@ -8041,12 +8070,17 @@
{
/* Special operand. */
adj_opcode = op_code - lh->opcode_base;
- address += (adj_opcode / lh->line_range)
- * lh->minimum_instruction_length;
+ address += (((op_index + (adj_opcode / lh->line_range))
+ / lh->maximum_ops_per_instruction)
+ * lh->minimum_instruction_length);
+ op_index = ((op_index + (adj_opcode / lh->line_range))
+ % lh->maximum_ops_per_instruction);
line += lh->line_base + (adj_opcode % lh->line_range);
if (lh->num_file_names < file || file == 0)
dwarf2_debug_line_missing_file_complaint ();
- else
+ /* For now we ignore lines not starting on an
+ instruction boundary. */
+ else if (op_index == 0)
{
lh->file_names[file - 1].included_p = 1;
if (!decode_for_pst_p && is_stmt)
@@ -8081,6 +8115,7 @@
break;
case DW_LNE_set_address:
address = read_address (abfd, line_ptr, cu, &bytes_read);
+ op_index = 0;
line_ptr += bytes_read;
address += baseaddr;
break;
@@ -8146,9 +8181,17 @@
basic_block = 0;
break;
case DW_LNS_advance_pc:
- address += lh->minimum_instruction_length
- * read_unsigned_leb128 (abfd, line_ptr, &bytes_read);
- line_ptr += bytes_read;
+ {
+ CORE_ADDR adjust
+ = read_unsigned_leb128 (abfd, line_ptr, &bytes_read);
+
+ address += (((op_index + adjust)
+ / lh->maximum_ops_per_instruction)
+ * lh->minimum_instruction_length);
+ op_index = ((op_index + adjust)
+ % lh->maximum_ops_per_instruction);
+ line_ptr += bytes_read;
+ }
break;
case DW_LNS_advance_line:
line += read_signed_leb128 (abfd, line_ptr, &bytes_read);
@@ -8195,11 +8238,19 @@
instruction length since special opcode 255 would have
scaled the the increment. */
case DW_LNS_const_add_pc:
- address += (lh->minimum_instruction_length
- * ((255 - lh->opcode_base) / lh->line_range));
+ {
+ CORE_ADDR adjust = (255 - lh->opcode_base) / lh->line_range;
+
+ address += (((op_index + adjust)
+ / lh->maximum_ops_per_instruction)
+ * lh->minimum_instruction_length);
+ op_index = ((op_index + adjust)
+ % lh->maximum_ops_per_instruction);
+ }
break;
case DW_LNS_fixed_advance_pc:
address += read_2_bytes (abfd, line_ptr);
+ op_index = 0;
line_ptr += 2;
break;
default:
@@ -8761,6 +8812,7 @@
case DW_FORM_block2:
case DW_FORM_block4:
case DW_FORM_block:
+ case DW_FORM_exprloc:
blk = DW_BLOCK (attr);
if (TYPE_LENGTH (SYMBOL_TYPE (sym)) != blk->size)
dwarf2_const_value_length_mismatch_complaint (SYMBOL_PRINT_NAME (sym),
@@ -10308,6 +10360,10 @@
case DW_FORM_block1:
fprintf_unfiltered (f, "block: size %d", DW_BLOCK (&die->attrs[i])->size);
break;
+ case DW_FORM_exprloc:
+ fprintf_unfiltered (f, "expression: size %u",
+ DW_BLOCK (&die->attrs[i])->size);
+ break;
case DW_FORM_ref1:
case DW_FORM_ref2:
case DW_FORM_ref4:
@@ -10323,6 +10379,10 @@
fprintf_unfiltered (f, "constant: %s",
pulongest (DW_UNSND (&die->attrs[i])));
break;
+ case DW_FORM_sec_offset:
+ fprintf_unfiltered (f, "section offset: %s",
+ pulongest (DW_UNSND (&die->attrs[i])));
+ break;
case DW_FORM_sig8:
if (DW_SIGNATURED_TYPE (&die->attrs[i]) != NULL)
fprintf_unfiltered (f, "signatured type, offset: 0x%x",
@@ -10343,6 +10403,9 @@
else
fprintf_unfiltered (f, "flag: FALSE");
break;
+ case DW_FORM_flag_present:
+ fprintf_unfiltered (f, "flag: TRUE");
+ break;
case DW_FORM_indirect:
/* the reader will have reduced the indirect form to
the "base form" so this form should not occur */
@@ -11520,7 +11583,8 @@
attr->form == DW_FORM_block1
|| attr->form == DW_FORM_block2
|| attr->form == DW_FORM_block4
- || attr->form == DW_FORM_block);
+ || attr->form == DW_FORM_block
+ || attr->form == DW_FORM_exprloc);
}
/* Return non-zero if ATTR's value is a section offset --- classes
@@ -11535,7 +11599,8 @@
attr_form_is_section_offset (struct attribute *attr)
{
return (attr->form == DW_FORM_data4
- || attr->form == DW_FORM_data8);
+ || attr->form == DW_FORM_data8
+ || attr->form == DW_FORM_sec_offset);
}