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Re: PATCH: Check if DW_OP_fbreg has DW_AT_frame_base
- From: "H. J. Lu" <hjl at lucon dot org>
- To: binutils at sources dot redhat dot com
- Date: Tue, 4 Jan 2005 14:10:35 -0800
- Subject: Re: PATCH: Check if DW_OP_fbreg has DW_AT_frame_base
- References: <20050104183237.GA28216@lucon.org>
On Tue, Jan 04, 2005 at 10:32:37AM -0800, H. J. Lu wrote:
> DW_OP_fbreg needs DW_AT_frame_base. But gcc generates it without
> DW_AT_frame_base:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19124
>
> This patch checks if DW_OP_fbreg has DW_AT_frame_base.
>
>
I also noticed that base address isn't handled for location list at
all. This updated patch fixes it.
H.J.
----
2005-01-04 H.J. Lu <hongjiu.lu@intel.com>
* readelf.c (have_frame_base): New.
(need_base_address): Likewise.
(saved_base_address): Likewise.
(decode_location_expression): Return 1 if DW_AT_frame_base is
needed.
(debug_info): Add base_address and a have_frame_base pointer.
(read_and_display_attr_value): Replace saved_DW_AT_low_pc with
saved_base_address. Record base address. Set have_frame_base.
Record if a location list has DW_AT_frame_base. Display if a
location expression has no DW_AT_frame_base but needs one. Set
saved_base_address only if needed.
(process_debug_info): Clear have_frame_base, saved_base_address
and set need_base_address.
(display_debug_loc): Display if a location expression has no
DW_AT_frame_base but needs one. Display if start >= end.
Properly handle base address.
(process_object): Free the have_frame_base pointer in
debug_info.
--- binutils/readelf.c.frame 2005-01-04 09:20:26.000000000 -0800
+++ binutils/readelf.c 2005-01-04 13:58:20.085892273 -0800
@@ -168,6 +168,9 @@ int do_debug_loc;
int do_arch;
int do_notes;
int is_32bit_elf;
+int have_frame_base;
+int need_base_address;
+unsigned long saved_base_address;
struct group_list
{
@@ -7551,7 +7554,7 @@ display_block (unsigned char *data, unsi
return data;
}
-static void
+static int
decode_location_expression (unsigned char * data,
unsigned int pointer_size,
unsigned long length,
@@ -7561,6 +7564,7 @@ decode_location_expression (unsigned cha
int bytes_read;
unsigned long uvalue;
unsigned char *end = data + length;
+ int need_frame_base = 0;
while (data < end)
{
@@ -7823,6 +7827,7 @@ decode_location_expression (unsigned cha
data += bytes_read;
break;
case DW_OP_fbreg:
+ need_frame_base = 1;
printf ("DW_OP_fbreg: %ld", read_leb128 (data, &bytes_read, 1));
data += bytes_read;
break;
@@ -7879,13 +7884,15 @@ decode_location_expression (unsigned cha
else
printf (_("(Unknown location op)"));
/* No way to tell where the next op is, so just bail. */
- return;
+ return need_frame_base;
}
/* Separate the ops. */
if (data < end)
printf ("; ");
}
+
+ return need_frame_base;
}
/* Decode a DW_AT_ranges attribute for 64bit DWARF3 . */
@@ -8008,8 +8015,10 @@ typedef struct
{
unsigned int pointer_size;
unsigned long cu_offset;
+ unsigned long base_address;
/* This is an array of offsets to the location list table. */
unsigned long *loc_offsets;
+ int *have_frame_base;
unsigned int num_loc_offsets;
unsigned int max_loc_offsets;
}
@@ -8031,7 +8040,6 @@ read_and_display_attr_value (unsigned lo
debug_info *debug_info_p,
int do_loc)
{
- static unsigned long saved_DW_AT_low_pc = 0;
unsigned long uvalue = 0;
unsigned char *block_start = NULL;
int bytes_read;
@@ -8221,6 +8229,7 @@ read_and_display_attr_value (unsigned lo
switch (attribute)
{
case DW_AT_frame_base:
+ have_frame_base = 1;
case DW_AT_location:
case DW_AT_data_member_location:
case DW_AT_vtable_elem_location:
@@ -8242,12 +8251,21 @@ read_and_display_attr_value (unsigned lo
debug_info_p->loc_offsets
= xrealloc (debug_info_p->loc_offsets,
max * sizeof (*debug_info_p->loc_offsets));
+ debug_info_p->have_frame_base
+ = xrealloc (debug_info_p->have_frame_base,
+ max * sizeof (*debug_info_p->have_frame_base));
debug_info_p->max_loc_offsets = max;
}
debug_info_p->loc_offsets [num] = uvalue;
+ debug_info_p->have_frame_base [num] = have_frame_base;
debug_info_p->num_loc_offsets++;
}
break;
+
+ case DW_AT_low_pc:
+ if (need_base_address)
+ debug_info_p->base_address = uvalue;
+ break;
default:
break;
@@ -8401,6 +8419,7 @@ read_and_display_attr_value (unsigned lo
break;
case DW_AT_frame_base:
+ have_frame_base = 1;
case DW_AT_location:
case DW_AT_data_member_location:
case DW_AT_vtable_elem_location:
@@ -8412,9 +8431,16 @@ read_and_display_attr_value (unsigned lo
case DW_AT_lower_bound:
if (block_start)
{
+ int need_frame_base;
+
printf ("(");
- decode_location_expression (block_start, pointer_size, uvalue, cu_offset);
+ need_frame_base = decode_location_expression (block_start,
+ pointer_size,
+ uvalue,
+ cu_offset);
printf (")");
+ if (need_frame_base && !have_frame_base)
+ printf (_(" [without DW_AT_frame_base]"));
}
else if (form == DW_FORM_data4 || form == DW_FORM_data8)
printf (_("(location list)"));
@@ -8422,15 +8448,12 @@ read_and_display_attr_value (unsigned lo
break;
case DW_AT_low_pc:
- /* This is a hack. We keep track of the DW_AT_low_pc attributes
- and use them when decoding DW_AT_ranges attributes. The
- assumption here is that we are decoding the attributes in order
- and so the correct base address for the range is the low_pc. */
- saved_DW_AT_low_pc = uvalue;
+ if (need_base_address)
+ saved_base_address = uvalue;
break;
case DW_AT_ranges:
- decode_range (uvalue, saved_DW_AT_low_pc);
+ decode_range (uvalue, saved_base_address);
break;
default:
@@ -8691,7 +8714,9 @@ process_debug_info (Elf_Internal_Shdr *s
debug_information [unit].cu_offset = cu_offset;
debug_information [unit].pointer_size
= compunit.cu_pointer_size;
+ debug_information [unit].base_address = 0;
debug_information [unit].loc_offsets = NULL;
+ debug_information [unit].have_frame_base = NULL;
debug_information [unit].max_loc_offsets = 0;
debug_information [unit].num_loc_offsets = 0;
}
@@ -8779,6 +8804,24 @@ process_debug_info (Elf_Internal_Shdr *s
abbrev_number,
get_TAG_name (entry->tag));
+ switch (entry->tag)
+ {
+ default:
+ need_base_address = 0;
+ break;
+ case DW_TAG_compile_unit:
+ need_base_address = 1;
+ saved_base_address = 0;
+ break;
+ case DW_TAG_entry_point:
+ case DW_TAG_inlined_subroutine:
+ case DW_TAG_subprogram:
+ need_base_address = 0;
+ /* Assuming that there is no DW_AT_frame_base. */
+ have_frame_base = 0;
+ break;
+ }
+
for (attr = entry->first_attr; attr; attr = attr->next)
tags = read_and_display_attr (attr->attribute,
attr->form,
@@ -9468,14 +9511,19 @@ display_debug_loc (Elf_Internal_Shdr *se
unsigned long offset;
unsigned int pointer_size;
unsigned long cu_offset;
+ unsigned long base_address;
+ int need_frame_base;
+ int has_frame_base;
pointer_size = debug_information [i].pointer_size;
cu_offset = debug_information [i].cu_offset;
for (j = 0; j < debug_information [i].num_loc_offsets; j++)
{
+ has_frame_base = debug_information [i].have_frame_base [j];
offset = debug_information [i].loc_offsets [j];
next = section_begin + offset;
+ base_address = debug_information [i].base_address;
if (!seen_first_offset)
seen_first_offset = 1;
@@ -9500,9 +9548,12 @@ display_debug_loc (Elf_Internal_Shdr *se
if (begin == 0 && end == 0)
break;
- /* For now, skip any base address specifiers. */
- if (begin == 0xffffffff)
- continue;
+ /* Check base address specifiers. */
+ if (begin == -1UL && end != -1UL)
+ {
+ base_address = end;
+ continue;
+ }
begin += addr;
end += addr;
@@ -9511,14 +9562,22 @@ display_debug_loc (Elf_Internal_Shdr *se
start += 2;
printf (" %8.8lx %8.8lx %8.8lx (",
- offset, begin, end);
- decode_location_expression (start, pointer_size, length,
- cu_offset);
- printf (")\n");
-
- if (begin >= end)
- warn ("Bad location list at %8.8lx from %8.8lx to %8.8lx\n",
- offset, begin, end);
+ offset, begin + base_address, end + base_address);
+ need_frame_base = decode_location_expression (start,
+ pointer_size,
+ length,
+ cu_offset);
+ putchar (')');
+
+ if (need_frame_base && !has_frame_base)
+ printf (_(" [without DW_AT_frame_base]"));
+
+ if (begin == end)
+ fputs (_(" (start == end)"), stdout);
+ else if (begin > end)
+ fputs (_(" (start > end)"), stdout);
+
+ putchar ('\n');
start += length;
}
@@ -11748,8 +11807,11 @@ process_object (char *file_name, FILE *f
if (debug_information)
{
for (i = 0; i < num_debug_info_entries; i++)
- if (debug_information [i].loc_offsets != NULL)
- free (debug_information [i].loc_offsets);
+ if (!debug_information [i].max_loc_offsets)
+ {
+ free (debug_information [i].loc_offsets);
+ free (debug_information [i].have_frame_base);
+ }
free (debug_information);
debug_information = NULL;
num_debug_info_entries = 0;