gas/doc/as.info-9

This is as.info, produced by makeinfo version 4.3 from as.texinfo.

START-INFO-DIR-ENTRY
* As: (as).                     The GNU assembler.
* Gas: (as).                    The GNU assembler.
END-INFO-DIR-ENTRY

   This file documents the GNU Assembler "as".

   Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002
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 1.1 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
Texts.  A copy of the license is included in the section entitled "GNU
Free Documentation License".


File: as.info,  Node: VAX-Opts,  Next: VAX-float,  Up: Vax-Dependent

VAX Command-Line Options
------------------------

   The Vax version of `as' accepts any of the following options, gives
a warning message that the option was ignored and proceeds.  These
options are for compatibility with scripts designed for other people's
assemblers.

``-D' (Debug)'
``-S' (Symbol Table)'
``-T' (Token Trace)'
     These are obsolete options used to debug old assemblers.

``-d' (Displacement size for JUMPs)'
     This option expects a number following the `-d'.  Like options
     that expect filenames, the number may immediately follow the `-d'
     (old standard) or constitute the whole of the command line
     argument that follows `-d' (GNU standard).

``-V' (Virtualize Interpass Temporary File)'
     Some other assemblers use a temporary file.  This option commanded
     them to keep the information in active memory rather than in a
     disk file.  `as' always does this, so this option is redundant.

``-J' (JUMPify Longer Branches)'
     Many 32-bit computers permit a variety of branch instructions to
     do the same job.  Some of these instructions are short (and fast)
     but have a limited range; others are long (and slow) but can
     branch anywhere in virtual memory.  Often there are 3 flavors of
     branch: short, medium and long.  Some other assemblers would emit
     short and medium branches, unless told by this option to emit
     short and long branches.

``-t' (Temporary File Directory)'
     Some other assemblers may use a temporary file, and this option
     takes a filename being the directory to site the temporary file.
     Since `as' does not use a temporary disk file, this option makes
     no difference.  `-t' needs exactly one filename.

   The Vax version of the assembler accepts additional options when
compiled for VMS:

`-h N'
     External symbol or section (used for global variables) names are
     not case sensitive on VAX/VMS and always mapped to upper case.
     This is contrary to the C language definition which explicitly
     distinguishes upper and lower case.  To implement a standard
     conforming C compiler, names must be changed (mapped) to preserve
     the case information.  The default mapping is to convert all lower
     case characters to uppercase and adding an underscore followed by
     a 6 digit hex value, representing a 24 digit binary value.  The
     one digits in the binary value represent which characters are
     uppercase in the original symbol name.

     The `-h N' option determines how we map names.  This takes several
     values.  No `-h' switch at all allows case hacking as described
     above.  A value of zero (`-h0') implies names should be upper
     case, and inhibits the case hack.  A value of 2 (`-h2') implies
     names should be all lower case, with no case hack.  A value of 3
     (`-h3') implies that case should be preserved.  The value 1 is
     unused.  The `-H' option directs `as' to display every mapped
     symbol during assembly.

     Symbols whose names include a dollar sign `$' are exceptions to the
     general name mapping.  These symbols are normally only used to
     reference VMS library names.  Such symbols are always mapped to
     upper case.

`-+'
     The `-+' option causes `as' to truncate any symbol name larger
     than 31 characters.  The `-+' option also prevents some code
     following the `_main' symbol normally added to make the object
     file compatible with Vax-11 "C".

`-1'
     This option is ignored for backward compatibility with `as'
     version 1.x.

`-H'
     The `-H' option causes `as' to print every symbol which was
     changed by case mapping.


File: as.info,  Node: VAX-float,  Next: VAX-directives,  Prev: VAX-Opts,  Up: Vax-Dependent

VAX Floating Point
------------------

   Conversion of flonums to floating point is correct, and compatible
with previous assemblers.  Rounding is towards zero if the remainder is
exactly half the least significant bit.

   `D', `F', `G' and `H' floating point formats are understood.

   Immediate floating literals (_e.g._ `S`$6.9') are rendered
correctly.  Again, rounding is towards zero in the boundary case.

   The `.float' directive produces `f' format numbers.  The `.double'
directive produces `d' format numbers.


File: as.info,  Node: VAX-directives,  Next: VAX-opcodes,  Prev: VAX-float,  Up: Vax-Dependent

Vax Machine Directives
----------------------

   The Vax version of the assembler supports four directives for
generating Vax floating point constants.  They are described in the
table below.

`.dfloat'
     This expects zero or more flonums, separated by commas, and
     assembles Vax `d' format 64-bit floating point constants.

`.ffloat'
     This expects zero or more flonums, separated by commas, and
     assembles Vax `f' format 32-bit floating point constants.

`.gfloat'
     This expects zero or more flonums, separated by commas, and
     assembles Vax `g' format 64-bit floating point constants.

`.hfloat'
     This expects zero or more flonums, separated by commas, and
     assembles Vax `h' format 128-bit floating point constants.


File: as.info,  Node: VAX-opcodes,  Next: VAX-branch,  Prev: VAX-directives,  Up: Vax-Dependent

VAX Opcodes
-----------

   All DEC mnemonics are supported.  Beware that `case...' instructions
have exactly 3 operands.  The dispatch table that follows the `case...'
instruction should be made with `.word' statements.  This is compatible
with all unix assemblers we know of.


File: as.info,  Node: VAX-branch,  Next: VAX-operands,  Prev: VAX-opcodes,  Up: Vax-Dependent

VAX Branch Improvement
----------------------

   Certain pseudo opcodes are permitted.  They are for branch
instructions.  They expand to the shortest branch instruction that
reaches the target.  Generally these mnemonics are made by substituting
`j' for `b' at the start of a DEC mnemonic.  This feature is included
both for compatibility and to help compilers.  If you do not need this
feature, avoid these opcodes.  Here are the mnemonics, and the code
they can expand into.

`jbsb'
     `Jsb' is already an instruction mnemonic, so we chose `jbsb'.
    (byte displacement)
          `bsbb ...'

    (word displacement)
          `bsbw ...'

    (long displacement)
          `jsb ...'

`jbr'
`jr'
     Unconditional branch.
    (byte displacement)
          `brb ...'

    (word displacement)
          `brw ...'

    (long displacement)
          `jmp ...'

`jCOND'
     COND may be any one of the conditional branches `neq', `nequ',
     `eql', `eqlu', `gtr', `geq', `lss', `gtru', `lequ', `vc', `vs',
     `gequ', `cc', `lssu', `cs'.  COND may also be one of the bit tests
     `bs', `bc', `bss', `bcs', `bsc', `bcc', `bssi', `bcci', `lbs',
     `lbc'.  NOTCOND is the opposite condition to COND.
    (byte displacement)
          `bCOND ...'

    (word displacement)
          `bNOTCOND foo ; brw ... ; foo:'

    (long displacement)
          `bNOTCOND foo ; jmp ... ; foo:'

`jacbX'
     X may be one of `b d f g h l w'.
    (word displacement)
          `OPCODE ...'

    (long displacement)
               OPCODE ..., foo ;
               brb bar ;
               foo: jmp ... ;
               bar:

`jaobYYY'
     YYY may be one of `lss leq'.

`jsobZZZ'
     ZZZ may be one of `geq gtr'.
    (byte displacement)
          `OPCODE ...'

    (word displacement)
               OPCODE ..., foo ;
               brb bar ;
               foo: brw DESTINATION ;
               bar:

    (long displacement)
               OPCODE ..., foo ;
               brb bar ;
               foo: jmp DESTINATION ;
               bar:

`aobleq'
`aoblss'
`sobgeq'
`sobgtr'

    (byte displacement)
          `OPCODE ...'

    (word displacement)
               OPCODE ..., foo ;
               brb bar ;
               foo: brw DESTINATION ;
               bar:

    (long displacement)
               OPCODE ..., foo ;
               brb bar ;
               foo: jmp DESTINATION ;
               bar:


File: as.info,  Node: VAX-operands,  Next: VAX-no,  Prev: VAX-branch,  Up: Vax-Dependent

VAX Operands
------------

   The immediate character is `$' for Unix compatibility, not `#' as
DEC writes it.

   The indirect character is `*' for Unix compatibility, not `@' as DEC
writes it.

   The displacement sizing character is ``' (an accent grave) for Unix
compatibility, not `^' as DEC writes it.  The letter preceding ``' may
have either case.  `G' is not understood, but all other letters (`b i l
s w') are understood.

   Register names understood are `r0 r1 r2 ... r15 ap fp sp pc'.  Upper
and lower case letters are equivalent.

   For instance
     tstb *w`$4(r5)

   Any expression is permitted in an operand.  Operands are comma
separated.


File: as.info,  Node: VAX-no,  Prev: VAX-operands,  Up: Vax-Dependent

Not Supported on VAX
--------------------

   Vax bit fields can not be assembled with `as'.  Someone can add the
required code if they really need it.


File: as.info,  Node: V850-Dependent,  Next: Z8000-Dependent,  Prev: Sparc-Dependent,  Up: Machine Dependencies

v850 Dependent Features
=======================

* Menu:

* V850 Options::              Options
* V850 Syntax::               Syntax
* V850 Floating Point::       Floating Point
* V850 Directives::           V850 Machine Directives
* V850 Opcodes::              Opcodes


File: as.info,  Node: V850 Options,  Next: V850 Syntax,  Up: V850-Dependent

Options
-------

   `as' supports the following additional command-line options for the
V850 processor family:

`-wsigned_overflow'
     Causes warnings to be produced when signed immediate values
     overflow the space available for then within their opcodes.  By
     default this option is disabled as it is possible to receive
     spurious warnings due to using exact bit patterns as immediate
     constants.

`-wunsigned_overflow'
     Causes warnings to be produced when unsigned immediate values
     overflow the space available for then within their opcodes.  By
     default this option is disabled as it is possible to receive
     spurious warnings due to using exact bit patterns as immediate
     constants.

`-mv850'
     Specifies that the assembled code should be marked as being
     targeted at the V850 processor.  This allows the linker to detect
     attempts to link such code with code assembled for other
     processors.

`-mv850e'
     Specifies that the assembled code should be marked as being
     targeted at the V850E processor.  This allows the linker to detect
     attempts to link such code with code assembled for other
     processors.

`-mv850any'
     Specifies that the assembled code should be marked as being
     targeted at the V850 processor but support instructions that are
     specific to the extended variants of the process.  This allows the
     production of binaries that contain target specific code, but
     which are also intended to be used in a generic fashion.  For
     example libgcc.a contains generic routines used by the code
     produced by GCC for all versions of the v850 architecture,
     together with support routines only used by the V850E architecture.


File: as.info,  Node: V850 Syntax,  Next: V850 Floating Point,  Prev: V850 Options,  Up: V850-Dependent

Syntax
------

* Menu:

* V850-Chars::                Special Characters
* V850-Regs::                 Register Names


File: as.info,  Node: V850-Chars,  Next: V850-Regs,  Up: V850 Syntax

Special Characters
..................

   `#' is the line comment character.


File: as.info,  Node: V850-Regs,  Prev: V850-Chars,  Up: V850 Syntax

Register Names
..............

   `as' supports the following names for registers:
`general register 0'
     r0, zero

`general register 1'
     r1

`general register 2'
     r2, hp

`general register 3'
     r3, sp

`general register 4'
     r4, gp

`general register 5'
     r5, tp

`general register 6'
     r6

`general register 7'
     r7

`general register 8'
     r8

`general register 9'
     r9

`general register 10'
     r10

`general register 11'
     r11

`general register 12'
     r12

`general register 13'
     r13

`general register 14'
     r14

`general register 15'
     r15

`general register 16'
     r16

`general register 17'
     r17

`general register 18'
     r18

`general register 19'
     r19

`general register 20'
     r20

`general register 21'
     r21

`general register 22'
     r22

`general register 23'
     r23

`general register 24'
     r24

`general register 25'
     r25

`general register 26'
     r26

`general register 27'
     r27

`general register 28'
     r28

`general register 29'
     r29

`general register 30'
     r30, ep

`general register 31'
     r31, lp

`system register 0'
     eipc

`system register 1'
     eipsw

`system register 2'
     fepc

`system register 3'
     fepsw

`system register 4'
     ecr

`system register 5'
     psw

`system register 16'
     ctpc

`system register 17'
     ctpsw

`system register 18'
     dbpc

`system register 19'
     dbpsw

`system register 20'
     ctbp


File: as.info,  Node: V850 Floating Point,  Next: V850 Directives,  Prev: V850 Syntax,  Up: V850-Dependent

Floating Point
--------------

   The V850 family uses IEEE floating-point numbers.


File: as.info,  Node: V850 Directives,  Next: V850 Opcodes,  Prev: V850 Floating Point,  Up: V850-Dependent

V850 Machine Directives
-----------------------

`.offset <EXPRESSION>'
     Moves the offset into the current section to the specified amount.

`.section "name", <type>'
     This is an extension to the standard .section directive.  It sets
     the current section to be <type> and creates an alias for this
     section called "name".

`.v850'
     Specifies that the assembled code should be marked as being
     targeted at the V850 processor.  This allows the linker to detect
     attempts to link such code with code assembled for other
     processors.

`.v850e'
     Specifies that the assembled code should be marked as being
     targeted at the V850E processor.  This allows the linker to detect
     attempts to link such code with code assembled for other
     processors.


File: as.info,  Node: V850 Opcodes,  Prev: V850 Directives,  Up: V850-Dependent

Opcodes
-------

   `as' implements all the standard V850 opcodes.

   `as' also implements the following pseudo ops:

`hi0()'
     Computes the higher 16 bits of the given expression and stores it
     into the immediate operand field of the given instruction.  For
     example:

     `mulhi hi0(here - there), r5, r6'

     computes the difference between the address of labels 'here' and
     'there', takes the upper 16 bits of this difference, shifts it
     down 16 bits and then mutliplies it by the lower 16 bits in
     register 5, putting the result into register 6.

`lo()'
     Computes the lower 16 bits of the given expression and stores it
     into the immediate operand field of the given instruction.  For
     example:

     `addi lo(here - there), r5, r6'

     computes the difference between the address of labels 'here' and
     'there', takes the lower 16 bits of this difference and adds it to
     register 5, putting the result into register 6.

`hi()'
     Computes the higher 16 bits of the given expression and then adds
     the value of the most significant bit of the lower 16 bits of the
     expression and stores the result into the immediate operand field
     of the given instruction.  For example the following code can be
     used to compute the address of the label 'here' and store it into
     register 6:

     `movhi hi(here), r0, r6'     `movea lo(here), r6, r6'

     The reason for this special behaviour is that movea performs a sign
     extention on its immediate operand.  So for example if the address
     of 'here' was 0xFFFFFFFF then without the special behaviour of the
     hi() pseudo-op the movhi instruction would put 0xFFFF0000 into r6,
     then the movea instruction would takes its immediate operand,
     0xFFFF, sign extend it to 32 bits, 0xFFFFFFFF, and then add it
     into r6 giving 0xFFFEFFFF which is wrong (the fifth nibble is E).
     With the hi() pseudo op adding in the top bit of the lo() pseudo
     op, the movhi instruction actually stores 0 into r6 (0xFFFF + 1 =
     0x0000), so that the movea instruction stores 0xFFFFFFFF into r6 -
     the right value.

`hilo()'
     Computes the 32 bit value of the given expression and stores it
     into the immediate operand field of the given instruction (which
     must be a mov instruction).  For example:

     `mov hilo(here), r6'

     computes the absolute address of label 'here' and puts the result
     into register 6.

`sdaoff()'
     Computes the offset of the named variable from the start of the
     Small Data Area (whoes address is held in register 4, the GP
     register) and stores the result as a 16 bit signed value in the
     immediate operand field of the given instruction.  For example:

     `ld.w sdaoff(_a_variable)[gp],r6'

     loads the contents of the location pointed to by the label
     '_a_variable' into register 6, provided that the label is located
     somewhere within +/- 32K of the address held in the GP register.
     [Note the linker assumes that the GP register contains a fixed
     address set to the address of the label called '__gp'.  This can
     either be set up automatically by the linker, or specifically set
     by using the `--defsym __gp=<value>' command line option].

`tdaoff()'
     Computes the offset of the named variable from the start of the
     Tiny Data Area (whoes address is held in register 30, the EP
     register) and stores the result as a 4,5, 7 or 8 bit unsigned
     value in the immediate operand field of the given instruction.
     For example:

     `sld.w tdaoff(_a_variable)[ep],r6'

     loads the contents of the location pointed to by the label
     '_a_variable' into register 6, provided that the label is located
     somewhere within +256 bytes of the address held in the EP
     register.  [Note the linker assumes that the EP register contains
     a fixed address set to the address of the label called '__ep'.
     This can either be set up automatically by the linker, or
     specifically set by using the `--defsym __ep=<value>' command line
     option].

`zdaoff()'
     Computes the offset of the named variable from address 0 and
     stores the result as a 16 bit signed value in the immediate
     operand field of the given instruction.  For example:

     `movea zdaoff(_a_variable),zero,r6'

     puts the address of the label '_a_variable' into register 6,
     assuming that the label is somewhere within the first 32K of
     memory.  (Strictly speaking it also possible to access the last
     32K of memory as well, as the offsets are signed).

`ctoff()'
     Computes the offset of the named variable from the start of the
     Call Table Area (whoes address is helg in system register 20, the
     CTBP register) and stores the result a 6 or 16 bit unsigned value
     in the immediate field of then given instruction or piece of data.
     For example:

     `callt ctoff(table_func1)'

     will put the call the function whoes address is held in the call
     table at the location labeled 'table_func1'.

   For information on the V850 instruction set, see `V850 Family
32-/16-Bit single-Chip Microcontroller Architecture Manual' from NEC.
Ltd.


File: as.info,  Node: Reporting Bugs,  Next: Acknowledgements,  Prev: Machine Dependencies,  Up: Top

Reporting Bugs
**************

   Your bug reports play an essential role in making `as' reliable.

   Reporting a bug may help you by bringing a solution to your problem,
or it may not.  But in any case the principal function of a bug report
is to help the entire community by making the next version of `as' work
better.  Bug reports are your contribution to the maintenance of `as'.

   In order for a bug report to serve its purpose, you must include the
information that enables us to fix the bug.

* Menu:

* Bug Criteria::                Have you found a bug?
* Bug Reporting::               How to report bugs


File: as.info,  Node: Bug Criteria,  Next: Bug Reporting,  Up: Reporting Bugs

Have you found a bug?
=====================

   If you are not sure whether you have found a bug, here are some
guidelines:

   * If the assembler gets a fatal signal, for any input whatever, that
     is a `as' bug.  Reliable assemblers never crash.

   * If `as' produces an error message for valid input, that is a bug.

   * If `as' does not produce an error message for invalid input, that
     is a bug.  However, you should note that your idea of "invalid
     input" might be our idea of "an extension" or "support for
     traditional practice".

   * If you are an experienced user of assemblers, your suggestions for
     improvement of `as' are welcome in any case.


File: as.info,  Node: Bug Reporting,  Prev: Bug Criteria,  Up: Reporting Bugs

How to report bugs
==================

   A number of companies and individuals offer support for GNU
products.  If you obtained `as' from a support organization, we
recommend you contact that organization first.

   You can find contact information for many support companies and
individuals in the file `etc/SERVICE' in the GNU Emacs distribution.

   In any event, we also recommend that you send bug reports for `as'
to `bug-binutils@gnu.org'.

   The fundamental principle of reporting bugs usefully is this:
*report all the facts*.  If you are not sure whether to state a fact or
leave it out, state it!

   Often people omit facts because they think they know what causes the
problem and assume that some details do not matter.  Thus, you might
assume that the name of a symbol you use in an example does not matter.
Well, probably it does not, but one cannot be sure.  Perhaps the bug
is a stray memory reference which happens to fetch from the location
where that name is stored in memory; perhaps, if the name were
different, the contents of that location would fool the assembler into
doing the right thing despite the bug.  Play it safe and give a
specific, complete example.  That is the easiest thing for you to do,
and the most helpful.

   Keep in mind that the purpose of a bug report is to enable us to fix
the bug if it is new to us.  Therefore, always write your bug reports
on the assumption that the bug has not been reported previously.

   Sometimes people give a few sketchy facts and ask, "Does this ring a
bell?"  Those bug reports are useless, and we urge everyone to _refuse
to respond to them_ except to chide the sender to report bugs properly.

   To enable us to fix the bug, you should include all these things:

   * The version of `as'.  `as' announces it if you start it with the
     `--version' argument.

     Without this, we will not know whether there is any point in
     looking for the bug in the current version of `as'.

   * Any patches you may have applied to the `as' source.

   * The type of machine you are using, and the operating system name
     and version number.

   * What compiler (and its version) was used to compile `as'--e.g.
     "`gcc-2.7'".

   * The command arguments you gave the assembler to assemble your
     example and observe the bug.  To guarantee you will not omit
     something important, list them all.  A copy of the Makefile (or
     the output from make) is sufficient.

     If we were to try to guess the arguments, we would probably guess
     wrong and then we might not encounter the bug.

   * A complete input file that will reproduce the bug.  If the bug is
     observed when the assembler is invoked via a compiler, send the
     assembler source, not the high level language source.  Most
     compilers will produce the assembler source when run with the `-S'
     option.  If you are using `gcc', use the options `-v
     --save-temps'; this will save the assembler source in a file with
     an extension of `.s', and also show you exactly how `as' is being
     run.

   * A description of what behavior you observe that you believe is
     incorrect.  For example, "It gets a fatal signal."

     Of course, if the bug is that `as' gets a fatal signal, then we
     will certainly notice it.  But if the bug is incorrect output, we
     might not notice unless it is glaringly wrong.  You might as well
     not give us a chance to make a mistake.

     Even if the problem you experience is a fatal signal, you should
     still say so explicitly.  Suppose something strange is going on,
     such as, your copy of `as' is out of synch, or you have
     encountered a bug in the C library on your system.  (This has
     happened!)  Your copy might crash and ours would not.  If you told
     us to expect a crash, then when ours fails to crash, we would know
     that the bug was not happening for us.  If you had not told us to
     expect a crash, then we would not be able to draw any conclusion
     from our observations.

   * If you wish to suggest changes to the `as' source, send us context
     diffs, as generated by `diff' with the `-u', `-c', or `-p' option.
     Always send diffs from the old file to the new file.  If you even
     discuss something in the `as' source, refer to it by context, not
     by line number.

     The line numbers in our development sources will not match those
     in your sources.  Your line numbers would convey no useful
     information to us.

   Here are some things that are not necessary:

   * A description of the envelope of the bug.

     Often people who encounter a bug spend a lot of time investigating
     which changes to the input file will make the bug go away and which
     changes will not affect it.

     This is often time consuming and not very useful, because the way
     we will find the bug is by running a single example under the
     debugger with breakpoints, not by pure deduction from a series of
     examples.  We recommend that you save your time for something else.

     Of course, if you can find a simpler example to report _instead_
     of the original one, that is a convenience for us.  Errors in the
     output will be easier to spot, running under the debugger will take
     less time, and so on.

     However, simplification is not vital; if you do not want to do
     this, report the bug anyway and send us the entire test case you
     used.

   * A patch for the bug.

     A patch for the bug does help us if it is a good one.  But do not
     omit the necessary information, such as the test case, on the
     assumption that a patch is all we need.  We might see problems
     with your patch and decide to fix the problem another way, or we
     might not understand it at all.

     Sometimes with a program as complicated as `as' it is very hard to
     construct an example that will make the program follow a certain
     path through the code.  If you do not send us the example, we will
     not be able to construct one, so we will not be able to verify
     that the bug is fixed.

     And if we cannot understand what bug you are trying to fix, or why
     your patch should be an improvement, we will not install it.  A
     test case will help us to understand.

   * A guess about what the bug is or what it depends on.

     Such guesses are usually wrong.  Even we cannot guess right about
     such things without first using the debugger to find the facts.


File: as.info,  Node: Acknowledgements,  Next: GNU Free Documentation License,  Prev: Reporting Bugs,  Up: Top

Acknowledgements
****************

   If you have contributed to `as' and your name isn't listed here, it
is not meant as a slight.  We just don't know about it.  Send mail to
the maintainer, and we'll correct the situation.  Currently the
maintainer is Ken Raeburn (email address `raeburn@cygnus.com').

   Dean Elsner wrote the original GNU assembler for the VAX.(1)

   Jay Fenlason maintained GAS for a while, adding support for
GDB-specific debug information and the 68k series machines, most of the
preprocessing pass, and extensive changes in `messages.c',
`input-file.c', `write.c'.

   K. Richard Pixley maintained GAS for a while, adding various
enhancements and many bug fixes, including merging support for several
processors, breaking GAS up to handle multiple object file format back
ends (including heavy rewrite, testing, an integration of the coff and
b.out back ends), adding configuration including heavy testing and
verification of cross assemblers and file splits and renaming,
converted GAS to strictly ANSI C including full prototypes, added
support for m680[34]0 and cpu32, did considerable work on i960
including a COFF port (including considerable amounts of reverse
engineering), a SPARC opcode file rewrite, DECstation, rs6000, and
hp300hpux host ports, updated "know" assertions and made them work,
much other reorganization, cleanup, and lint.

   Ken Raeburn wrote the high-level BFD interface code to replace most
of the code in format-specific I/O modules.

   The original VMS support was contributed by David L. Kashtan.  Eric
Youngdale has done much work with it since.

   The Intel 80386 machine description was written by Eliot Dresselhaus.

   Minh Tran-Le at IntelliCorp contributed some AIX 386 support.

   The Motorola 88k machine description was contributed by Devon Bowen
of Buffalo University and Torbjorn Granlund of the Swedish Institute of
Computer Science.

   Keith Knowles at the Open Software Foundation wrote the original
MIPS back end (`tc-mips.c', `tc-mips.h'), and contributed Rose format
support (which hasn't been merged in yet).  Ralph Campbell worked with
the MIPS code to support a.out format.

   Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors
(tc-z8k, tc-h8300, tc-h8500), and IEEE 695 object file format
(obj-ieee), was written by Steve Chamberlain of Cygnus Support.  Steve
also modified the COFF back end to use BFD for some low-level
operations, for use with the H8/300 and AMD 29k targets.

   John Gilmore built the AMD 29000 support, added `.include' support,
and simplified the configuration of which versions accept which
directives.  He updated the 68k machine description so that Motorola's
opcodes always produced fixed-size instructions (e.g. `jsr'), while
synthetic instructions remained shrinkable (`jbsr').  John fixed many
bugs, including true tested cross-compilation support, and one bug in
relaxation that took a week and required the proverbial one-bit fix.

   Ian Lance Taylor of Cygnus Support merged the Motorola and MIT
syntax for the 68k, completed support for some COFF targets (68k, i386
SVR3, and SCO Unix), added support for MIPS ECOFF and ELF targets,
wrote the initial RS/6000 and PowerPC assembler, and made a few other
minor patches.

   Steve Chamberlain made `as' able to generate listings.

   Hewlett-Packard contributed support for the HP9000/300.

   Jeff Law wrote GAS and BFD support for the native HPPA object format
(SOM) along with a fairly extensive HPPA testsuite (for both SOM and
ELF object formats).  This work was supported by both the Center for
Software Science at the University of Utah and Cygnus Support.

   Support for ELF format files has been worked on by Mark Eichin of
Cygnus Support (original, incomplete implementation for SPARC), Pete
Hoogenboom and Jeff Law at the University of Utah (HPPA mainly),
Michael Meissner of the Open Software Foundation (i386 mainly), and Ken
Raeburn of Cygnus Support (sparc, and some initial 64-bit support).

   Linas Vepstas added GAS support for the ESA/390 "IBM 370"
architecture.

   Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote
GAS and BFD support for openVMS/Alpha.

   Timothy Wall, Michael Hayes, and Greg Smart contributed to the
various tic* flavors.

   Several engineers at Cygnus Support have also provided many small
bug fixes and configuration enhancements.

   Many others have contributed large or small bugfixes and
enhancements.  If you have contributed significant work and are not
mentioned on this list, and want to be, let us know.  Some of the
history has been lost; we are not intentionally leaving anyone out.

   ---------- Footnotes ----------

   (1) Any more details?