[Bug middle-end/24932] New: GCC segfault's on strcmp in tree.c:annotate_with_file_line

[Bug middle-end/24932] New: GCC segfault's on strcmp in tree.c:annotate_with_file_line

[barbieri at gmail dot com]

I'm writing a tutorial on a HelloWorld compiler front-end for GCC
(http://svn.gna.org/viewcvs/gsc/branches/hello-world/doc/hello.xml) and noticed
that a function with statements but no DECL_SOURCE_FILE set, seg-faults on 
cgraph_finalize_function(), because it calls
gimple-low.c:lower_function_body(), which in turn does:

SET_EXPR_LOCATION (x, cfun->function_end_locus);

however, if cfun->function_end_locus is empty ({NULL, 0}), it will call
tree.c:annotate_with_file_line() with file=NULL, and it will fail on this "if":

  if (last_annotated_node
      && last_annotated_node->line == line
      && (last_annotated_node->file == file
          || !strcmp (last_annotated_node->file, file)))

because strcmp (last_annotated_node->file, file), with file=NULL will
seg-fault.

The attached patch checks if file is NULL before using strcmp.

The program that fails build is:
http://svn.gna.org/viewcvs/gsc/branches/hello-world/compiler/hello1.c?rev=551


-- 
           Summary: GCC segfault's on strcmp in
                    tree.c:annotate_with_file_line
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: barbieri at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24932

[Bug middle-end/24932] GCC segfault's on strcmp in tree.c:annotate_with_file_line

[barbieri at gmail dot com]

------- Comment #1 from barbieri at gmail dot com  2005-11-18 18:09 -------
Created an attachment (id=10274)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=10274&action=view)
gcc-annotate_with_file_line.patch

Fix segfault


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24932

[Bug middle-end/24932] GCC segfault's on strcmp in tree.c:annotate_with_file_line

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2005-11-18 18:17 -------
Actually this should never happen in general.  Your front-end really should be
adding locus on the statements.

I will let someone else decide if this is a real middle-end bug or a bug in
your front-end.

I should note that I don't like the check in annotate_with_file_line at all.  I
would rather have a check in gimple-low.c instead.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24932

[Bug middle-end/24932] GCC segfault's on strcmp in tree.c:annotate_with_file_line

[barbieri at gmail dot com]

------- Comment #3 from barbieri at gmail dot com  2005-11-18 18:36 -------
Created an attachment (id=10276)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=10276&action=view)
gcc-lower_function_body.patch

Alternative patch that also fix seg fault, but earlier.

It's uglier than the previous, and is more restricted, since it just protect
the behaviour from gimple-low.c:lower_function_body(), while the previous patch
does the check for every use of annotate_with_file_line, used by
SET_EXPR_LOCATION.

I cannot know if this is a bug in the middle-end, since there is no
documentation on when I need to set this value. If so, probably we can use
gcc_assert() to confirm this?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24932

[Bug middle-end/24932] GCC segfault's on strcmp in tree.c:annotate_with_file_line

[barbieri at gmail dot com]

------- Comment #4 from barbieri at gmail dot com  2005-12-07 10:49 -------
So, this is a bug.

I just need a confirmation if it's a bug in the middle-end layer, so there is
already a patch, or if this is a bug in the front-end, then I will add the
check to the gimplify code.

Since there is no documentation on the expected behaviour, we need to be safe.

Also, it would be good to have this before our presentation at LinuxConf.AU,
then we can be sure what's expected and how to teach others.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24932

[Bug middle-end/24932] GCC segfault's on strcmp in tree.c:annotate_with_file_line

[barbieri at gmail dot com]

------- Comment #5 from barbieri at gmail dot com  2005-12-24 22:47 -------
any news on this front?

I'll present a tutorial in LinuxConf.au and need to know if front-end should
provide the information or middle-end should handle it.

In both cases I'll provide the patch to gcc, but I need to know where the bug
is.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24932

[Bug middle-end/24932] GCC segfault's on strcmp in tree.c:annotate_with_file_line

[steven at gcc dot gnu dot org]

------- Comment #6 from steven at gcc dot gnu dot org  2009-02-22 16:36 -------
Locations are now handled differently (mapped locations).


-- 

steven at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24932