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8.11.1 Options

The i386 version of as has a few machine dependent options:

--32 | --64
Select the word size, either 32 bits or 64 bits. Selecting 32-bit implies Intel i386 architecture, while 64-bit implies AMD x86-64 architecture.

These options are only available with the ELF object file format, and require that the necessary BFD support has been included (on a 32-bit platform you have to add –enable-64-bit-bfd to configure enable 64-bit usage and use x86-64 as target platform).

By default, x86 GAS replaces multiple nop instructions used for alignment within code sections with multi-byte nop instructions such as leal 0(%esi,1),%esi. This switch disables the optimization.

On SVR4-derived platforms, the character `/' is treated as a comment character, which means that it cannot be used in expressions. The `--divide' option turns `/' into a normal character. This does not disable `/' at the beginning of a line starting a comment, or affect using `#' for starting a comment.