7.35 .file

There are two different versions of the .file directive. Targets that support DWARF2 line number information use the DWARF2 version of .file . Other targets use the default version.

Default Version

This version of the .file directive tells as that we are about to start a new logical file. The syntax is:

     .file string

string is the new file name. In general, the filename is recognized whether or not it is surrounded by quotes ‘ " ’; but if you wish to specify an empty file name, you must give the quotes–"" . This statement may go away in future: it is only recognized to be compatible with old as programs.

DWARF2 Version

When emitting DWARF2 line number information, .file assigns filenames to the .debug_line file name table. The syntax is:

     .file fileno

The fileno operand should be a unique positive integer to use as the index of the entry in the table. The filename operand is a C string literal.

The detail of filename indices is exposed to the user because the filename table is shared with the .debug_info section of the DWARF2 debugging information, and thus the user must know the exact indices that table entries will have.