From: nick clifton <nickc@redhat.com>
To: "Kaushik, Praveen_Kumar" <Praveen_Kumar.Kaushi@atmel.com>,
gdb@sourceware.org
Cc: binutils@sourceware.org
Subject: Re: Debuggin info for unused sections
Date: Fri, 06 Jan 2012 10:27:00 -0000 [thread overview]
Message-ID: <4F06CC32.10102@redhat.com> (raw)
In-Reply-To: <DB7B9DAED0B660469F69536325A1D65A042E0781@penmb01.corp.atmel.com>
Hi Praveen,
[I have added the GDB list as I now think that this issue affects them.]
> While using -gc-sections to remove unused sections, the section is removed but the debug info in not removed.
>
> In,
>
> a.c:
> int main()
> {
> return 0;
> }
> int fun ()
> {
> return 0;
> }
> gcc -g3 -ffunction-sections -Wl,-gc-sections a.c
> readelf -wl a.out
> gives
>
> Line Number Statements:
> Extended opcode 2: set Address to 0x4003f6
> Special opcode 6: advance Address by 0 to 0x4003f6 and Line by 1 to 2
> Special opcode 62: advance Address by 4 to 0x4003fa and Line by 1 to 3
> Special opcode 76: advance Address by 5 to 0x4003ff and Line by 1 to 4
> Advance PC by 2 to 0x400401
> Extended opcode 1: End of Sequence
>
> Extended opcode 2: set Address to 0x0
> Special opcode 11: advance Address by 0 to 0x0 and Line by 6 to 7
> Special opcode 62: advance Address by 4 to 0x4 and Line by 1 to 8
> Special opcode 76: advance Address by 5 to 0x9 and Line by 1 to 9
> Advance PC by 2 to 0xb
> Extended opcode 1: End of Sequence
Originally I had just thought that this was a missed opportunity for the
linker to remove unneeded debug information. But then it occurred to me
that leaving the bogus line number information in could cause problems
for GDB. As in:
% gdb -nw a.out
GNU gdb (GDB) 7.4.50.20120106-cvs
[...]
(gdb) break a.c:6
Bus error (core dumped)
So it seems that we really do need to remove it after all. I will look
into it when I have the time.
Cheers
Nick
next parent reply other threads:[~2012-01-06 10:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <DB7B9DAED0B660469F69536325A1D65A042E0781@penmb01.corp.atmel.com>
2012-01-06 10:27 ` nick clifton [this message]
2012-01-06 11:39 ` Andrew Burgess
2012-01-06 14:11 ` Tom Tromey
2012-01-06 16:01 ` nick clifton
2012-01-06 23:11 ` Cary Coutant
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