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Re: Reference to .debug_loc
On Fri, Feb 14, 2003 at 02:24:43PM -0500, Daniel Berlin wrote:
> On Friday, February 14, 2003, at 10:26 AM, Daniel Jacobowitz wrote:
> >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)
> >>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.
> Err, why?
> If they are in different files, it should be adjusting the offsets when
> it merges the sections together, no?
Look at that operand. It's the difference of two local labels - it
gets resolved at assembly time.
> >>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.
> It's supposed to be the offset from the beginning of the debug_loc
> Will this do that?
I think so. The result will be something like .Ldebug_ranges0 +
(.LLST0-.Ldebug_loc0). If the assembler won't take that then we'll
have to track addresses for loclists the same as we do for rangelists.
MontaVista Software Debian GNU/Linux Developer