| Assembler File Names and Line Numbers

Input Files

There are two ways of locating a line in the input file (or files) and either may be used in reporting error messages. One way refers to a line number in a physical file; the other refers to a line number in a "logical" file. See Error and Warning Messages.
Physical files are those files named in the command line given to `as`.
Logical files are simply names declared explicitly by assembler directives; they bear no relation to physical files. Logical file names help error messages reflect the original source file, when `as` source is itself synthesized from other files. `as` understands the `#` directives emitted by the `gcc` preprocessor. See also `.file`.