Hi,

I encountered a problem when trying CVS HEAD gdb with gcc-4.1, which has
no .debug_ranges support. Below is the test case:

$ cat main.c
int main ()
{
    return 0;
}

extern void __attribute__ ((__section__ (".init.text"))) foo_init (void);
void foo_init ()
{
    return;
}

$ cat foo.c
int foo ()
{
    return 0;
}

$ gcc-4.1 -o test main.c foo.c -g

CVS HEAD gdb cannot show the source line of foo.
$ gdb test
GNU gdb (GDB) 6.8.50.20081020-cvs
[snip]
(gdb) b foo
Breakpoint 1 at 0x400458

while gdb-6.8 can
$ gdb test
GNU gdb 6.8
[snip]
(gdb) b foo
Breakpoint 1 at 0x400458: file foo.c, line 3.

Since gcc-4.1 does not generate .debug_ranges, gdb tries to create
addrmap from low_pc and high_pc. When creating mutable addrmap, the
address range of main.c is treated as contiguous, e.g. [0x400448,
0x40053e], while foo.c is e.g. [0x400454, 0x40045f], which is embedded
in the former. In current gdb, the value of the start and end
transitions for foo.c are initialized as same as the value of the start
one for main.c. Then later in addrmap_mutable_set_empty, those
transitions are removed.

This patch should fix this case. Is it OK?


Regards,
Jie