[PATCH 3/6] DWARF Two Level Line Tables: check_line_address

Doug Evans
2015-03-12T20:03:25Z

Hi.

This patch just factors out the checking of a line address
to improve the S/N ratio of the calling function.

2015-03-12 Doug Evans <dje@google.com>

* dwarf2read.c (record_line_ftype): New typedef.
(check_line_address): New function.
(dwarf_decode_lines_1): Call it.

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index d980b1a..fff5474 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -17429,6 +17429,11 @@ psymtab_include_file_name (const struct line_header *lh, int file_index,
return include_name;
}

+/* Function to record a line number. */
+
+typedef void (record_line_ftype) (struct subfile *subfile, int line,
+ CORE_ADDR pc);
+
/* Ignore this record_line request. */

static void
@@ -17528,6 +17533,36 @@ dwarf_finish_line (struct gdbarch *gdbarch, struct subfile *subfile,
dwarf_record_line (gdbarch, subfile, 0, address, p_record_line);
}

+/* Check address and if invalid nop-out the rest of the lines in this
+ sequence. */
+
+static void
+check_line_address (struct dwarf2_cu *cu, record_line_ftype **p_record_line,
+ const gdb_byte *line_ptr,
+ CORE_ADDR lowpc, CORE_ADDR address)
+{
+ /* If address < lowpc then it's not a usable value, it's outside the
+ pc range of the CU. However, we restrict the test to only address
+ values of zero to preserve GDB's previous behaviour which is to
+ handle the specific case of a function being GC'd by the linker. */
+
+ if (address == 0 && address < lowpc)
+ {
+ /* This line table is for a function which has been
+ GCd by the linker. Ignore it. PR gdb/12528 */
+
+ struct objfile *objfile = cu->objfile;
+ long line_offset = line_ptr - get_debug_line_section (cu)->buffer;
+
+ complaint (&symfile_complaints,
+ _(".debug_line address at offset 0x%lx is 0 [in module %s]"),
+ line_offset, objfile_name (objfile));
+ *p_record_line = noop_record_line;
+ /* Note: *p_record_line is left as noop_record_line
+ until we see DW_LNE_end_sequence. */
+ }
+}
+
/* Subroutine of dwarf_decode_lines to simplify it.
Process the line number information in LH. */

@@ -17661,31 +17696,10 @@ dwarf_decode_lines_1 (struct line_header *lh, struct dwarf2_cu *cu,
break;
case DW_LNE_set_address:
address = read_address (abfd, line_ptr, cu, &bytes_read);
-
- /* If address < lowpc then it's not a usable value, it's
- outside the pc range of the CU. However, we restrict
- the test to only address values of zero to preserve
- GDB's previous behaviour which is to handle the specific
- case of a function being GC'd by the linker. */
- if (address == 0 && address < lowpc)
- {
- /* This line table is for a function which has been
- GCd by the linker. Ignore it. PR gdb/12528 */
-
- long line_offset
- = line_ptr - get_debug_line_section (cu)->buffer;
-
- complaint (&symfile_complaints,
- _(".debug_line address at offset 0x%lx is 0 "
- "[in module %s]"),
- line_offset, objfile_name (objfile));
- p_record_line = noop_record_line;
- /* Note: p_record_line is left as noop_record_line
- until we see DW_LNE_end_sequence. */
- }
-
- op_index = 0;
line_ptr += bytes_read;
+ check_line_address (cu, &p_record_line, line_ptr,
+ lowpc, address);
+ op_index = 0;
address += baseaddr;
address = gdbarch_adjust_dwarf2_line (gdbarch, address, 0);
break;