\input texinfo @c -*-Texinfo-*-
-@c Copyright (C) 1991-2015 Free Software Foundation, Inc.
+@c Copyright (C) 1991-2016 Free Software Foundation, Inc.
@c UPDATE!! On future updates--
@c (1) check for new machine-dep cmdline options in
@c md_parse_option definitions in config/tc-*.c
This file documents the GNU Assembler "@value{AS}".
@c man begin COPYRIGHT
-Copyright @copyright{} 1991-2015 Free Software Foundation, Inc.
+Copyright @copyright{} 1991-2016 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
@end tex
@vskip 0pt plus 1filll
-Copyright @copyright{} 1991-2015 Free Software Foundation, Inc.
+Copyright @copyright{} 1991-2016 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
[@b{-W}] [@b{--warn}] [@b{--fatal-warnings}] [@b{-w}] [@b{-x}]
[@b{-Z}] [@b{@@@var{FILE}}]
[@b{--sectname-subst}] [@b{--size-check=[error|warning]}]
+ [@b{--elf-stt-common=[no|yes]}]
[@b{--target-help}] [@var{target-options}]
[@b{--}|@var{files} @dots{}]
@c
+@c man end
@c Target dependent options are listed below. Keep the list sorted.
@c Add an empty line for separation.
+@c man begin TARGET
@ifset AARCH64
@emph{Target AArch64 options:}
[@b{-mcpu=@var{cpu}}]
[@b{-mA6}|@b{-mARC600}|@b{-mARC601}|@b{-mA7}|@b{-mARC700}|@b{-mEM}|@b{-mHS}]
[@b{-mcode-density}]
+ [@b{-mrelax}]
[@b{-EB}|@b{-EL}]
@end ifset
@ifset ARM
[@b{-mdmx}] [@b{-no-mdmx}]
[@b{-mdsp}] [@b{-mno-dsp}]
[@b{-mdspr2}] [@b{-mno-dspr2}]
+ [@b{-mdspr3}] [@b{-mno-dspr3}]
[@b{-mmsa}] [@b{-mno-msa}]
[@b{-mxpa}] [@b{-mno-xpa}]
[@b{-mmt}] [@b{-mno-mt}]
then debug line section will still be called just @var{.debug_line} without any
suffix.
+@ifset ELF
@item --size-check=error
@itemx --size-check=warning
Issue an error or warning for invalid ELF .size directive.
+@item --elf-stt-common=no
+@itemx --elf-stt-common=yes
+These options control whether the ELF assembler should generate common
+symbols with the @code{STT_COMMON} type. The default can be controlled
+by a configure option @option{--enable-elf-stt-common}.
+@end ifset
+
@item --help
Print a summary of the command line options and exit.
@item -mdspr2
@itemx -mno-dspr2
Generate code for the DSP Release 2 Application Specific Extension.
-This option implies -mdsp.
+This option implies @samp{-mdsp}.
This tells the assembler to accept DSP Release 2 instructions.
@samp{-mno-dspr2} turns off this option.
+@item -mdspr3
+@itemx -mno-dspr3
+Generate code for the DSP Release 3 Application Specific Extension.
+This option implies @samp{-mdsp} and @samp{-mdspr2}.
+This tells the assembler to accept DSP Release 3 instructions.
+@samp{-mno-dspr3} turns off this option.
+
@item -mmsa
@itemx -mno-msa
Generate code for the MIPS SIMD Architecture Extension.
@end smallexample
@noindent
-@cindex line numbers, in warnings/errors
-(where @b{NNN} is a line number). If a logical file name has been given
-(@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
-the current input file is used. If a logical line number was given
+@cindex file names and line numbers, in warnings/errors
+(where @b{NNN} is a line number). If both a logical file name
+(@pxref{File,,@code{.file}}) and a logical line number
@ifset GENERIC
(@pxref{Line,,@code{.line}})
@end ifset
-then it is used to calculate the number printed,
-otherwise the actual line in the current source file is printed. The
-message text is intended to be self explanatory (in the grand Unix
-tradition).
+have been given then they will be used, otherwise the file name and line number
+in the current assembler source file will be used. The message text is
+intended to be self explanatory (in the grand Unix tradition).
+
+Note the file name must be set via the logical version of the @code{.file}
+directive, not the DWARF2 version of the @code{.file} directive. For example:
+
+@smallexample
+ .file 2 "bar.c"
+ error_assembler_source
+ .file "foo.c"
+ .line 30
+ error_c_source
+@end smallexample
+
+produces this output:
+
+@smallexample
+ Assembler messages:
+ asm.s:2: Error: no such instruction: `error_assembler_source'
+ foo.c:31: Error: no such instruction: `error_c_source'
+@end smallexample
@cindex format of error messages
Error messages have the format
+
@smallexample
file_name:@b{NNN}:FATAL:Error Message Text
@end smallexample
+
The file name and line number are derived as for warning
messages. The actual message text may be rather less explanatory
because many of them aren't supposed to happen.
On targets that support compact unwinding tables these can be generated
by specifying @code{.eh_frame_entry} instead of @code{.eh_frame}.
+Some targets may support an additional name, such as @code{.c6xabi.exidx}
+which is used by the @value{TIC6X} target.
+
+The @code{.cfi_sections} directive can be repeated, with the same or different
+arguments, provided that CFI generation has not yet started. Once CFI
+generation has started however the section list is fixed and any attempts to
+redefine it will result in an error.
+
@subsection @code{.cfi_startproc [simple]}
@cindex @code{cfi_startproc} directive
@code{.cfi_startproc} is used at the beginning of each function that
Current value of @var{register} is the same like in the previous frame,
i.e. no restoration needed.
-@subsection @code{.cfi_remember_state},
-First save all current rules for all registers by @code{.cfi_remember_state},
-then totally screw them up by subsequent @code{.cfi_*} directives and when
-everything is hopelessly bad, use @code{.cfi_restore_state} to restore
-the previous saved state.
+@subsection @code{.cfi_remember_state} and @code{.cfi_restore_state}
+@code{.cfi_remember_state} pushes the set of rules for every register onto an
+implicit stack, while @code{.cfi_restore_state} pops them off the stack and
+places them in the current row. This is useful for situations where you have
+multiple @code{.cfi_*} directives that need to be undone due to the control
+flow of the program. For example, we could have something like this (assuming
+the CFA is the value of @code{rbp}):
+
+@smallexample
+ je label
+ popq %rbx
+ .cfi_restore %rbx
+ popq %r12
+ .cfi_restore %r12
+ popq %rbp
+ .cfi_restore %rbp
+ .cfi_def_cfa %rsp, 8
+ ret
+label:
+ /* Do something else */
+@end smallexample
+
+Here, we want the @code{.cfi} directives to affect only the rows corresponding
+to the instructions before @code{label}. This means we'd have to add multiple
+@code{.cfi} directives after @code{label} to recreate the original save
+locations of the registers, as well as setting the CFA back to the value of
+@code{rbp}. This would be clumsy, and result in a larger binary size. Instead,
+we can write:
+
+@smallexample
+ je label
+ popq %rbx
+ .cfi_remember_state
+ .cfi_restore %rbx
+ popq %r12
+ .cfi_restore %r12
+ popq %rbp
+ .cfi_restore %rbp
+ .cfi_def_cfa %rsp, 8
+ ret
+label:
+ .cfi_restore_state
+ /* Do something else */
+@end smallexample
+
+That way, the rules for the instructions after @code{label} will be the same
+as before the first @code{.cfi_restore} without having to use multiple
+@code{.cfi} directives.
@subsection @code{.cfi_return_column @var{register}}
Change return column @var{register}, i.e. the return address is either
If the optional argument is quoted, it is taken as flags to use for the
section. Each flag is a single character. The following flags are recognized:
+
@table @code
@item b
bss section (uninitialized data)
The optional @var{flags} argument is a quoted string which may contain any
combination of the following characters:
+
@table @code
@item a
section is allocatable
section is used for thread-local-storage
@item ?
section is a member of the previously-current section's group, if any
+@item @code{<number>}
+a numeric value indicating the bits to be set in the ELF section header's flags
+field. Note - if one or more of the alphabetic characters described above is
+also included in the flags field, their bit values will be ORed into the
+resulting value.
+@item @code{<target specific>}
+some targets extend this list with their own flag characters
@end table
+Note - once a section's flags have been set they cannot be changed. There are
+a few exceptions to this rule however. Processor and application specific
+flags can be added to an already defined section. The @code{.interp},
+@code{.strtab} and @code{.symtab} sections can have the allocate flag
+(@code{a}) set after they are initially defined, and the @code{.note-GNU-stack}
+section may have the executable (@code{x}) flag added.
+
The optional @var{type} argument may contain one of the following constants:
+
@table @code
@item @@progbits
section contains data
section contains an array of pointers to finish functions
@item @@preinit_array
section contains an array of pointers to pre-init functions
+@item @@@code{<number>}
+a numeric value to be set as the ELF section header's type field.
+@item @@@code{<target specific>}
+some targets extend this list with their own types
@end table
-Many targets only support the first three section types.
+Many targets only support the first three section types. The type may be
+enclosed in double quotes if necessary.
Note on targets where the @code{@@} character is the start of a comment (eg
ARM) then another character is used instead. For example the ARM port uses the
@code{%} character.
+Note - some sections, eg @code{.text} and @code{.data} are considered to be
+special and have fixed types. Any attempt to declare them with a different
+type will generate an error from the assembler.
+
If @var{flags} contains the @code{M} symbol then the @var{type} argument must
be specified as well as an extra argument---@var{entsize}---like this:
The @var{GroupName} field specifies the name of the section group to which this
particular section belongs. The optional linkage field can contain:
+
@table @code
@item comdat
indicates that only one copy of this section should be retained
Note that the section name is quoted. There may be a sequence of comma
separated flags:
+
@table @code
@item #alloc
section is allocatable
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