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Extraneous symbols in assembly file

Anonymous
Anonymous
Guru 17045 points

Hi,

 

I would like to ask about some symbols found in generated assembly file.

.asm file said:
$C$DW$5        .dwtag  DW_TAG_TI_loop
 
            .dwattr $C$DW$5, DW_AT_name("D:\workspace\examples\led\main.asm:$C$L1:1:1308433675")
            .dwattr $C$DW$5, DW_AT_TI_begin_file("main.c")
            .dwattr $C$DW$5, DW_AT_TI_begin_line(0x1a)
            .dwattr $C$DW$5, DW_AT_TI_end_line(0x20)
$C$DW$6        .dwtag  DW_TAG_TI_loop_range
            .dwattr $C$DW$6, DW_AT_low_pc($C$DW$L$_main$3$B)
            .dwattr $C$DW$6, DW_AT_high_pc($C$DW$L$_main$3$E)
$C$DW$7        .dwtag  DW_TAG_TI_loop_range
            .dwattr $C$DW$7, DW_AT_low_pc($C$DW$L$_main$4$B)
            .dwattr $C$DW$7, DW_AT_high_pc($C$DW$L$_main$4$E)
$C$DW$8        .dwtag  DW_TAG_TI_loop_range
            .dwattr $C$DW$8, DW_AT_low_pc($C$DW$L$_main$5$B)
            .dwattr $C$DW$8, DW_AT_high_pc($C$DW$L$_main$5$E)
            .dwendtag $C$DW$5

 

What are these various symbols? They are obviously not assembly instructions, so are they also like Archaeologist said in Miscellaneous assembly labels in a program, strictly for compiler use?

 

Are used by assembler or not? If the role of assembler is simply to translate assembly code into binary opcode, then the above symbol are irrelevant. So in syntax analysis phase (I assume assembler also has syntax analysis phase (?) , which is generic), assembler need to somehow handle them, for example, discarding (?).

 

But why are these symbols at all here? How does assembler actually treat them?

 

 

 

 

 

Thanks,

Zheng

  • 0
    TI__Guru* 84225 points

    Yes, they are strictly for compiler use.  The .dw* assembly directives represent DWARF debugging information.

  • Anonymous
    0 Anonymous in reply to Archaeologist
    Guru 17045 points

    Archaeologist and Aarti,

    From A Brief History of TI Object File Formats, I read that the object file could also contain information for debugging, which is in the "DWARF" format.

    However, even if I deleted all .obj files under the /debug directory, I could still debug with software breakpoints (I haven't tested hardware breakpoint, but in principle it is not or much less related file format). Why?

     

     

    Zheng

  • 0 in reply to Anonymous
    TI__Guru* 84225 points

    All of the debugging information in the object files was copied by the linker into the executable file, which is itself an object file.

  • Anonymous
    0 Anonymous in reply to Archaeologist
    Guru 17045 points

    Archaeologist,

    The output of linker is .out, so may I understand their relationship as:

    1. both .out and .obj are object files
    2. Differences
      1. .out is the relocated combination of other .obj files
      2. The suffix of .out is for distinguish it from the many .obj files. In CCS 3.3, .out file needs to be loaded manually, so choosing a different suffix also eliminate the chance of loading an un-relocated .obj file.

    ?

     

    Zheng

  • 0 in reply to Anonymous
    TI__Guru* 84225 points

    Technically the .obj files are "relocatable" object files, and the .out file is a "non-relocatable executable" object file.  However, usually when someone says "object file" they mean the relocatable object files.

    The file name suffixes are arbitrary.  From the compiler and linker point of view, the suffixes of the relocatable object files and the non-relocatable executable object file need not be .obj or .out, but yes, they are named so by convention to avoid confusion.

  • Anonymous
    0 Anonymous in reply to Archaeologist
    Guru 17045 points

    Archaeologist,

    I see it, thanks.

     

    Zheng