as for the Alpha supports many additional directives for
compatibility with the native assembler. This section describes them only
These are the additional directives in
as for the Alpha:
Specifies the target processor. This is equivalent to the -mcpu command-line option. See Options, for a list of values for cpu.
.ent function[, n]
Mark the beginning of function. An optional number may follow for
compatibility with the OSF/1 assembler, but is ignored. When generating
.mdebug information, this will create a procedure descriptor for
the function. In ELF, it will mark the symbol as a function a-la the
Mark the end of function. In ELF, it will set the size of the symbol
a-la the generic
.mask mask, offset
Indicate which of the integer registers are saved in the current
function’s stack frame. mask is interpreted a bit mask in which
bit n set indicates that register n is saved. The registers
are saved in a block located offset bytes from the canonical
frame address (CFA) which is the value of the stack pointer on entry to
the function. The registers are saved sequentially, except that the
return address register (normally
$26) is saved first.
This and the other directives that describe the stack frame are
currently only used when generating
.mdebug information. They
may in the future be used to generate DWARF2
information for hand written assembly.
.fmask mask, offset
Indicate which of the floating-point registers are saved in the current
stack frame. The mask and offset parameters are interpreted
.frame framereg, frameoffset, retreg[, argoffset]
Describes the shape of the stack frame. The frame pointer in use is
framereg; normally this is either
frame pointer is frameoffset bytes below the CFA. The return
address is initially located in retreg until it is saved as
.mask. For compatibility with OSF/1 an optional
argoffset parameter is accepted and ignored. It is believed to
indicate the offset from the CFA to the saved argument registers.
Indicate that the stack frame is set up and all registers have been
spilled. The argument n indicates whether and how the function
uses the incoming procedure vector (the address of the called
$27. 0 indicates that
$27 is not used; 1
indicates that the first two instructions of the function use
to perform a load of the GP register; 2 indicates that
used in some non-standard way and so the linker cannot elide the load of
the procedure vector during relaxation.
.usepv function, which
Used to indicate the use of the
$27 register, similar to
.prologue, but without the other semantics of needing to
be inside an open
The which argument should be either
no, indicating that
$27 is not used, or
std, indicating that the first two
instructions of the function perform a GP load.
One might use this directive instead of
.prologue if you are
also using dwarf2 CFI directives.
Computes the difference between the address in expression and the GP for the current object file, and stores it in 4 bytes. In addition to being smaller than a full 8 byte address, this also does not require a dynamic relocation when used in a shared library.
Stores expression as an IEEE double precision value.
Stores expression as an IEEE single precision value.
Stores expression as a VAX F format value.
Stores expression as a VAX G format value.
Stores expression as a VAX D format value.
Enables or disables various assembler features. Using the positive name of the feature enables while using ‘nofeature’ disables.
Indicates that macro expansions may clobber the assembler
$28) register. Some macros may not be
expanded without this and will generate an error message if
is in effect. When
at is in effect, a warning will be generated
$at is used by the programmer.
Enables the expansion of macro instructions. Note that variants of real
instructions, such as
br label vs
br $31,label are
considered alternate forms and not macros.
These control whether and how the assembler may re-order instructions.
Accepted for compatibility with the OSF/1 assembler, but
does not do instruction scheduling, so these features are ignored.
The following directives are recognized for compatibility with the OSF/1 assembler but are ignored.
.proc .aproc .reguse .livereg .option .aent .ugen .eflag .alias .noalias