@c Copyright (C) 2002-2024 Free Software Foundation, Inc.
@c   Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
@c This is part of the GAS manual.
@c For copying conditions, see the file as.texinfo.

@ifset GENERIC
@page
@node IA-64-Dependent
@chapter IA-64 Dependent Features
@end ifset

@ifclear GENERIC
@node Machine Dependencies
@chapter IA-64 Dependent Features
@end ifclear

@cindex IA-64 support
@menu
* IA-64 Options::              Options
* IA-64 Syntax::               Syntax
@c * IA-64 Floating Point::       Floating Point		// to be written
@c * IA-64 Directives::           IA-64 Machine Directives	// to be written
* IA-64 Opcodes::              Opcodes
@end menu

@node IA-64 Options
@section Options
@cindex IA-64 options
@cindex options for IA-64

@table @option
@cindex @code{-mconstant-gp} command-line option, IA-64

@item -mconstant-gp
This option instructs the assembler to mark the resulting object file
as using the ``constant GP'' model.  With this model, it is assumed
that the entire program uses a single global pointer (GP) value.  Note
that this option does not in any fashion affect the machine code
emitted by the assembler.  All it does is turn on the EF_IA_64_CONS_GP
flag in the ELF file header.

@item -mauto-pic
This option instructs the assembler to mark the resulting object file
as using the ``constant GP without function descriptor'' data model.
This model is like the ``constant GP'' model, except that it
additionally does away with function descriptors.  What this means is
that the address of a function refers directly to the function's code
entry-point.  Normally, such an address would refer to a function
descriptor, which contains both the code entry-point and the GP-value
needed by the function.  Note that this option does not in any fashion
affect the machine code emitted by the assembler.  All it does is
turn on the EF_IA_64_NOFUNCDESC_CONS_GP flag in the ELF file header.

@item -milp32
@itemx -milp64
@itemx -mlp64
@itemx -mp64
These options select the data model.  The assembler defaults to @code{-mlp64}
(LP64 data model).

@item -mle
@itemx -mbe
These options select the byte order.  The @code{-mle} option selects little-endian
byte order (default) and @code{-mbe} selects big-endian byte order.  Note that
IA-64 machine code always uses little-endian byte order.

@item -mtune=itanium1
@itemx -mtune=itanium2
Tune for a particular IA-64 CPU, @var{itanium1} or @var{itanium2}. The
default is @var{itanium2}.

@item -munwind-check=warning
@itemx -munwind-check=error
These options control what the assembler will do when performing
consistency checks on unwind directives.  @code{-munwind-check=warning}
will make the assembler issue a warning when an unwind directive check
fails.  This is the default.  @code{-munwind-check=error} will make the
assembler issue an error when an unwind directive check fails.

@item -mhint.b=ok
@itemx -mhint.b=warning
@itemx -mhint.b=error
These options control what the assembler will do when the @samp{hint.b}
instruction is used.  @code{-mhint.b=ok} will make the assembler accept
@samp{hint.b}.  @code{-mint.b=warning} will make the assembler issue a
warning when @samp{hint.b} is used.  @code{-mhint.b=error} will make
the assembler treat @samp{hint.b} as an error, which is the default.

@item -x
@itemx -xexplicit
These options turn on dependency violation checking.

@item -xauto
This option instructs the assembler to automatically insert stop bits where necessary
to remove dependency violations.  This is the default mode.

@item -xnone
This option turns off dependency violation checking.

@item -xdebug
This turns on debug output intended to help tracking down bugs in the dependency
violation checker.

@item -xdebugn
This is a shortcut for -xnone -xdebug.

@item -xdebugx
This is a shortcut for -xexplicit -xdebug.

@end table

@cindex IA-64 Syntax
@node IA-64 Syntax
@section Syntax
The assembler syntax closely follows the IA-64 Assembly Language
Reference Guide.

@menu
* IA-64-Chars::                Special Characters
* IA-64-Regs::                 Register Names
* IA-64-Bits::                 Bit Names
* IA-64-Relocs::               Relocations
@end menu

@node IA-64-Chars
@subsection Special Characters

@cindex line comment character, IA-64
@cindex IA-64 line comment character
@samp{//} is the line comment token.

@cindex line separator, IA-64
@cindex statement separator, IA-64
@cindex IA-64 line separator
@samp{;} can be used instead of a newline to separate statements.

@node IA-64-Regs
@subsection Register Names
@cindex IA-64 registers
@cindex register names, IA-64

The 128 integer registers are referred to as @samp{r@var{n}}.
The 128 floating-point registers are referred to as @samp{f@var{n}}.
The 128 application registers are referred to as @samp{ar@var{n}}.
The 128 control registers are referred to as @samp{cr@var{n}}.
The 64 one-bit predicate registers are referred to as @samp{p@var{n}}.
The 8 branch registers are referred to as @samp{b@var{n}}.
In addition, the assembler defines a number of aliases:
@samp{gp} (@samp{r1}), @samp{sp} (@samp{r12}), @samp{rp} (@samp{b0}),
@samp{ret0} (@samp{r8}), @samp{ret1} (@samp{r9}), @samp{ret2} (@samp{r10}),
@samp{ret3} (@samp{r9}), @samp{farg@var{n}} (@samp{f8+@var{n}}), and
@samp{fret@var{n}} (@samp{f8+@var{n}}).

For convenience, the assembler also defines aliases for all named application
and control registers.  For example, @samp{ar.bsp} refers to the register
backing store pointer (@samp{ar17}).  Similarly, @samp{cr.eoi} refers to
the end-of-interrupt register (@samp{cr67}).

@node IA-64-Bits
@subsection IA-64 Processor-Status-Register (PSR) Bit Names
@cindex IA-64 Processor-status-Register bit names
@cindex PSR bits
@cindex bit names, IA-64

The assembler defines bit masks for each of the bits in the IA-64
processor status register.  For example, @samp{psr.ic} corresponds to
a value of 0x2000.  These masks are primarily intended for use with
the @samp{ssm}/@samp{sum} and @samp{rsm}/@samp{rum}
instructions, but they can be used anywhere else where an integer
constant is expected.

@node IA-64-Relocs
@subsection Relocations
@cindex IA-64 relocations

In addition to the standard IA-64 relocations, the following relocations are
implemented by @code{@value{AS}}:

@table @code
@item @@slotcount(@var{V})
Convert the address offset @var{V} into a slot count.  This pseudo
function is available only on VMS.  The expression @var{V} must be
known at assembly time: it can't reference undefined symbols or symbols in
different sections.
@end table

@node IA-64 Opcodes
@section Opcodes
For detailed information on the IA-64 machine instruction set, see the
@c Attempt to work around a very overfull hbox.
@iftex
IA-64 Assembly Language Reference Guide available at
@smallfonts
@example
http://developer.intel.com/design/itanium/arch_spec.htm
@end example
@textfonts
@end iftex
@ifnottex
@uref{http://developer.intel.com/design/itanium/arch_spec.htm,IA-64 Architecture Handbook}.
@end ifnottex
