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Re: Handling corner case in building symbol table when "debug_line" includes compilation directory
- From: Maxim Grigoriev <maxim at tensilica dot com>
- To: Maxim Grigoriev <maxim at tensilica dot com>, gdb-patches at sources dot redhat dot com
- Date: Wed, 14 Mar 2007 21:30:23 -0700
- Subject: Re: Handling corner case in building symbol table when "debug_line" includes compilation directory
- References: <45F8A771.2060008@hq.tensilica.com> <20070315022735.GA9613@caradoc.them.org>
I've attached the patch separately. Now, it should be fine. Sorry for
inconvenience.
1) test case
extern int printf(const char *fmt,...);
int main()
{
printf("Hello, World !\n");
printf("Let's make DWARF consistent across all the tools !\n");
}
2) output from "readelf --debug-dump"
The section .debug_info contains:
Compilation Unit @ 0:
Length: 241
Version: 2
Abbrev Offset: 0
Pointer Size: 4
<0><b>: Abbrev Number: 1 (DW_TAG_compile_unit)
DW_AT_name : test.c
DW_AT_comp_dir : /home/maxim/W/BadgerPass/PR_14999
DW_AT_producer : xt-xcc for 7.1.2-development -O0
-OPT:align_instructions=32 -g2
DW_AT_language : 1 (ANSI C)
DW_AT_identifier_case: 0 (case_sensitive)
DW_AT_stmt_list : 0
[ . . . . . ]
Dump of debug contents of section .debug_line:
Length: 101
DWARF Version: 2
Prologue Length: 65
[ . . . . .]
The Directory Table:
/home/maxim/W/BadgerPass/PR_14999
The File Name Table:
Entry Dir Time Size Name
1 1 1173897037 152 test.c
* * * * *
So the compilation directory is listed in the directory table. And, there is
a reference from the file table pointing to this directory.
Normally, we wouldn't see a compilation directory in a line table prologue.
With my native GCC on the same test case I have:
<0><b>: Abbrev Number: 1 (DW_TAG_compile_unit)
DW_AT_stmt_list : 0
DW_AT_high_pc : 0x80483b6
DW_AT_low_pc : 0x8048384
DW_AT_producer : GNU C 4.1.1 20060525 (Red Hat 4.1.1-1)
DW_AT_language : 1 (ANSI C)
DW_AT_name : test.c
DW_AT_comp_dir : /home/maxim/W/BadgerPass/PR_14999
[ . . . . ]
The Directory Table is empty.
The File Name Table:
Entry Dir Time Size Name
1 0 0 0 test.c
So the compilation directory gets always described and referenced
explicitly.
Thanks for looking into this.
2007-03-15 Maxim Grigoriev <maxim2405@gmail.com>
* buildsym.c (start_subfile): Add handling missing case while
building symbol table for a compilation unit.
< Patch is attached >
Daniel Jacobowitz wrote:
On Wed, Mar 14, 2007 at 06:54:57PM -0700, Maxim Grigoriev wrote:
Hello All,
Tensilica compiler seems to provide a unique approach in building DWARF
line tables. It confuses GDB algorithms being used to build symbol tables.
First in DW_TAG_compile_unit entry
DW_AT_name is a source file name as it was used in a command line;
DW_AT_comp_dir is a full path name to a compilation directory;
Then in the statement program prologue, the directory table includes at
least one entry, which is again the compilation directory. And, there is
a corresponding file table entry referencing to this directory.
Assuming that this combination of the names of the directories and files
does not contradict DWARF standard, I think GDB has to handle this situation.
I suggest the following patch to fix this problem:
First of all, your mailer ate whitespace in the patch again - very
hard to read.
Unfortunately, I do not understand your description. Could you show
me an example?
Index: gdb/buildsym.c
===================================================================
RCS file: /cvs/src/src/gdb/buildsym.c,v
retrieving revision 1.47
diff -u -r1.47 buildsym.c
--- gdb/buildsym.c 27 Feb 2007 22:57:42 -0000 1.47
+++ gdb/buildsym.c 15 Mar 2007 01:14:14 -0000
@@ -549,7 +549,18 @@
for (subfile = subfiles; subfile; subfile = subfile->next)
{
- if (FILENAME_CMP (subfile->name, name) == 0)
+ char *subfile_name;
+ if (IS_ABSOLUTE_PATH(name) && !IS_ABSOLUTE_PATH (subfile->name))
+ {
+ subfile_name = concat (dirname, SLASH_STRING,
+ subfile->name, (char *)NULL);
+ make_cleanup (xfree, subfile_name);
+ }
+ else
+ {
+ subfile_name = subfile->name;
+ }
+ if (FILENAME_CMP (subfile_name, name) == 0)
{
current_subfile = subfile;
return;