#### 9.1.4 AArch64 Machine Directives

`.bss`
  This directive switches to the `.bss` section.

`.ltorg`
  This directive causes the current contents of the literal pool to be dumped into the current section (which is assumed to be the .text section) at the current location (aligned to a word boundary). `GAS` maintains a separate literal pool for each section and each sub-section. The `.ltorg` directive will only affect the literal pool of the current section and sub-section. At the end of assembly all remaining, un-empty literal pools will automatically be dumped.

  Note - older versions of `GAS` would dump the current literal pool any time a section change occurred. This is no longer done, since it prevents accurate control of the placement of literal pools.

`.pool`
  This is a synonym for .ltorg.

name`.req` register name
  This creates an alias for register name called name. For example:

                        foo .req w0

`.unreq` alias-name
  This undefines a register alias which was previously defined using the `req` directive. For example:

                        foo .req w0
                        .unreq foo

  An error occurs if the name is undefined. Note - this pseudo op can be used to delete builtin in register name aliases (eg 'w0'). This should only be done if it is really necessary.