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Re: Reference to .debug_loc
- From: Daniel Jacobowitz <drow at mvista dot com>
- To: Michal Ludvig <mludvig at suse dot cz>
- Cc: Daniel Berlin <dberlin at dberlin dot org>, gdb <gdb at sources dot redhat dot com>,gcc at sources dot redhat dot com
- Date: Fri, 14 Feb 2003 10:26:19 -0500
- Subject: Re: Reference to .debug_loc
- References: <3E4D03F3.40103@suse.cz>
On Fri, Feb 14, 2003 at 03:57:55PM +0100, Michal Ludvig wrote:
> Hi again,
> when location lists are in use, .debug_info looks like this:
>
> .section .debug_info
> .long 0x187 # Length of Compilation Unit Info
> .value 0x2 # DWARF version number
> .long .Ldebug_abbrev0 # Offset Into Abbrev. Section
> .byte 0x8 # Pointer Size (in bytes)
> .uleb128 0x1 # (DIE (0xb) DW_TAG_compile_unit)
> .long .Ldebug_line0 # DW_AT_stmt_list
> .quad .Letext0 # DW_AT_high_pc
> .quad .Ltext0 # DW_AT_low_pc
> .byte 0x1 # DW_AT_language
> [...]
> .uleb128 0x3 # (DIE (0x50) DW_TAG_formal_parameter)
> .long .LASF2 # DW_AT_name: "value"
> .byte 0x1 # DW_AT_decl_file
> .byte 0x2 # DW_AT_decl_line
> .long 0x8f # DW_AT_type
> .long .LLST0-.Ldebug_loc0 # DW_AT_location
>
> So, the reference to .debug_loc on the last line of the example
> (DW_AT_location) is an offset within that section, ie. it's 0 (NULL) for
> the first entry with a location list. However when I link several .o
> files together, each of them have DW_AT_location entries based at the
> same NULL.
>
> This time I realy can't see a way to find out at what position in the
> resulting (ie. linked from several ones) .debug_loc should I start
> reading for a given compilation unit.
>
> Should there be something more in the CU header? Something similar to
> .long .Ldebug_abbrev0 # Offset Into Abbrev. Section
> For example
> .long .Ldebug_loc0 # Offset Into Loclist Section
>
> Or is there another way?
At a guess it should be like DW_AT_ranges:
.long .Ldebug_ranges0+0x0 # DW_AT_ranges
I.E. dw2_asm_output_offset, rather than dw2_asm_output_delta, in GCC.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer