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@c Copyright 1991, 1992, 1993, 1994, 1995, 1997, 1999, 2000, 2001,
2
@c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
3
@c Free Software Foundation, Inc.
4
@c This is part of the GAS manual.
5
@c For copying conditions, see the file as.texinfo.
6
@ifset GENERIC
7
@page
8
@node MIPS-Dependent
9
@chapter MIPS Dependent Features
10
@end ifset
11
@ifclear GENERIC
12
@node Machine Dependencies
13
@chapter MIPS Dependent Features
14
@end ifclear
15
 
16
@cindex MIPS processor
17
@sc{gnu} @code{@value{AS}} for @sc{mips} architectures supports several
18
different @sc{mips} processors, and MIPS ISA levels I through V, MIPS32,
19
and MIPS64.  For information about the @sc{mips} instruction set, see
20
@cite{MIPS RISC Architecture}, by Kane and Heindrich (Prentice-Hall).
21
For an overview of @sc{mips} assembly conventions, see ``Appendix D:
22
Assembly Language Programming'' in the same work.
23
 
24
@menu
25
* MIPS Opts::           Assembler options
26
* MIPS Object::         ECOFF object code
27
* MIPS Stabs::          Directives for debugging information
28
* MIPS ISA::            Directives to override the ISA level
29
* MIPS symbol sizes::   Directives to override the size of symbols
30
* MIPS autoextend::     Directives for extending MIPS 16 bit instructions
31
* MIPS insn::           Directive to mark data as an instruction
32
* MIPS option stack::   Directives to save and restore options
33
* MIPS ASE instruction generation overrides:: Directives to control
34
                        generation of MIPS ASE instructions
35
* MIPS floating-point:: Directives to override floating-point options
36
* MIPS Syntax::         MIPS specific syntactical considerations
37
@end menu
38
 
39
@node MIPS Opts
40
@section Assembler options
41
 
42
The @sc{mips} configurations of @sc{gnu} @code{@value{AS}} support these
43
special options:
44
 
45
@table @code
46
@cindex @code{-G} option (MIPS)
47
@item -G @var{num}
48
This option sets the largest size of an object that can be referenced
49
implicitly with the @code{gp} register.  It is only accepted for targets
50
that use @sc{ecoff} format.  The default value is 8.
51
 
52
@cindex @code{-EB} option (MIPS)
53
@cindex @code{-EL} option (MIPS)
54
@cindex MIPS big-endian output
55
@cindex MIPS little-endian output
56
@cindex big-endian output, MIPS
57
@cindex little-endian output, MIPS
58
@item -EB
59
@itemx -EL
60
Any @sc{mips} configuration of @code{@value{AS}} can select big-endian or
61
little-endian output at run time (unlike the other @sc{gnu} development
62
tools, which must be configured for one or the other).  Use @samp{-EB}
63
to select big-endian output, and @samp{-EL} for little-endian.
64
 
65
@item -KPIC
66
@cindex PIC selection, MIPS
67
@cindex @option{-KPIC} option, MIPS
68
Generate SVR4-style PIC.  This option tells the assembler to generate
69
SVR4-style position-independent macro expansions.  It also tells the
70
assembler to mark the output file as PIC.
71
 
72
@item -mvxworks-pic
73
@cindex @option{-mvxworks-pic} option, MIPS
74
Generate VxWorks PIC.  This option tells the assembler to generate
75
VxWorks-style position-independent macro expansions.
76
 
77
@cindex MIPS architecture options
78
@item -mips1
79
@itemx -mips2
80
@itemx -mips3
81
@itemx -mips4
82
@itemx -mips5xo
83
@itemx -mips32
84
@itemx -mips32r2
85
@itemx -mips64
86
@itemx -mips64r2
87
Generate code for a particular MIPS Instruction Set Architecture level.
88
@samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
89
@samp{-mips2} to the @sc{r6000} processor, @samp{-mips3} to the
90
@sc{r4000} processor, and @samp{-mips4} to the @sc{r8000} and
91
@sc{r10000} processors.  @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2},
92
@samp{-mips64}, and @samp{-mips64r2}
93
correspond to generic
94
@sc{MIPS V}, @sc{MIPS32}, @sc{MIPS32 Release 2}, @sc{MIPS64},
95
and @sc{MIPS64 Release 2}
96
ISA processors, respectively.  You can also switch
97
instruction sets during the assembly; see @ref{MIPS ISA, Directives to
98
override the ISA level}.
99
 
100
@item -mgp32
101
@itemx -mfp32
102
Some macros have different expansions for 32-bit and 64-bit registers.
103
The register sizes are normally inferred from the ISA and ABI, but these
104
flags force a certain group of registers to be treated as 32 bits wide at
105
all times.  @samp{-mgp32} controls the size of general-purpose registers
106
and @samp{-mfp32} controls the size of floating-point registers.
107
 
108
The @code{.set gp=32} and @code{.set fp=32} directives allow the size
109
of registers to be changed for parts of an object. The default value is
110
restored by @code{.set gp=default} and @code{.set fp=default}.
111
 
112
On some MIPS variants there is a 32-bit mode flag; when this flag is
113
set, 64-bit instructions generate a trap.  Also, some 32-bit OSes only
114
save the 32-bit registers on a context switch, so it is essential never
115
to use the 64-bit registers.
116
 
117
@item -mgp64
118
@itemx -mfp64
119
Assume that 64-bit registers are available.  This is provided in the
120
interests of symmetry with @samp{-mgp32} and @samp{-mfp32}.
121
 
122
The @code{.set gp=64} and @code{.set fp=64} directives allow the size
123
of registers to be changed for parts of an object. The default value is
124
restored by @code{.set gp=default} and @code{.set fp=default}.
125
 
126
@item -mips16
127
@itemx -no-mips16
128
Generate code for the MIPS 16 processor.  This is equivalent to putting
129
@code{.set mips16} at the start of the assembly file.  @samp{-no-mips16}
130
turns off this option.
131
 
132
@item -msmartmips
133
@itemx -mno-smartmips
134
Enables the SmartMIPS extensions to the MIPS32 instruction set, which
135
provides a number of new instructions which target smartcard and
136
cryptographic applications.  This is equivalent to putting
137
@code{.set smartmips} at the start of the assembly file.
138
@samp{-mno-smartmips} turns off this option.
139
 
140
@item -mips3d
141
@itemx -no-mips3d
142
Generate code for the MIPS-3D Application Specific Extension.
143
This tells the assembler to accept MIPS-3D instructions.
144
@samp{-no-mips3d} turns off this option.
145
 
146
@item -mdmx
147
@itemx -no-mdmx
148
Generate code for the MDMX Application Specific Extension.
149
This tells the assembler to accept MDMX instructions.
150
@samp{-no-mdmx} turns off this option.
151
 
152
@item -mdsp
153
@itemx -mno-dsp
154
Generate code for the DSP Release 1 Application Specific Extension.
155
This tells the assembler to accept DSP Release 1 instructions.
156
@samp{-mno-dsp} turns off this option.
157
 
158
@item -mdspr2
159
@itemx -mno-dspr2
160
Generate code for the DSP Release 2 Application Specific Extension.
161
This option implies -mdsp.
162
This tells the assembler to accept DSP Release 2 instructions.
163
@samp{-mno-dspr2} turns off this option.
164
 
165
@item -mmt
166
@itemx -mno-mt
167
Generate code for the MT Application Specific Extension.
168
This tells the assembler to accept MT instructions.
169
@samp{-mno-mt} turns off this option.
170
 
171
@item -mfix7000
172
@itemx -mno-fix7000
173
Cause nops to be inserted if the read of the destination register
174
of an mfhi or mflo instruction occurs in the following two instructions.
175
 
176
@item -mfix-loongson2f-jump
177
@itemx -mno-fix-loongson2f-jump
178
Eliminate instruction fetch from outside 256M region to work around the
179
Loongson2F @samp{jump} instructions.  Without it, under extreme cases,
180
the kernel may crash.  The issue has been solved in latest processor
181
batches, but this fix has no side effect to them.
182
 
183
@item -mfix-loongson2f-nop
184
@itemx -mno-fix-loongson2f-nop
185
Replace nops by @code{or at,at,zero} to work around the Loongson2F
186
@samp{nop} errata.  Without it, under extreme cases, cpu might
187
deadlock.  The issue has been solved in latest loongson2f batches, but
188
this fix has no side effect to them.
189
 
190
@item -mfix-vr4120
191
@itemx -mno-fix-vr4120
192
Insert nops to work around certain VR4120 errata.  This option is
193
intended to be used on GCC-generated code: it is not designed to catch
194
all problems in hand-written assembler code.
195
 
196
@item -mfix-vr4130
197
@itemx -mno-fix-vr4130
198
Insert nops to work around the VR4130 @samp{mflo}/@samp{mfhi} errata.
199
 
200
@item -mfix-24k
201
@itemx -no-mfix-24k
202
Insert nops to work around the 24K @samp{eret}/@samp{deret} errata.
203
 
204
@item -mfix-cn63xxp1
205
@itemx -mno-fix-cn63xxp1
206
Replace @code{pref} hints 0 - 4 and 6 - 24 with hint 28 to work around
207
certain CN63XXP1 errata.
208
 
209
@item -m4010
210
@itemx -no-m4010
211
Generate code for the LSI @sc{r4010} chip.  This tells the assembler to
212
accept the @sc{r4010} specific instructions (@samp{addciu}, @samp{ffc},
213
etc.), and to not schedule @samp{nop} instructions around accesses to
214
the @samp{HI} and @samp{LO} registers.  @samp{-no-m4010} turns off this
215
option.
216
 
217
@item -m4650
218
@itemx -no-m4650
219
Generate code for the MIPS @sc{r4650} chip.  This tells the assembler to accept
220
the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
221
instructions around accesses to the @samp{HI} and @samp{LO} registers.
222
@samp{-no-m4650} turns off this option.
223
 
224
@itemx -m3900
225
@itemx -no-m3900
226
@itemx -m4100
227
@itemx -no-m4100
228
For each option @samp{-m@var{nnnn}}, generate code for the MIPS
229
@sc{r@var{nnnn}} chip.  This tells the assembler to accept instructions
230
specific to that chip, and to schedule for that chip's hazards.
231
 
232
@item -march=@var{cpu}
233
Generate code for a particular MIPS cpu.  It is exactly equivalent to
234
@samp{-m@var{cpu}}, except that there are more value of @var{cpu}
235
understood.  Valid @var{cpu} value are:
236
 
237
@quotation
238
2000,
239
3000,
240
3900,
241
4000,
242
4010,
243
4100,
244
4111,
245
vr4120,
246
vr4130,
247
vr4181,
248
4300,
249
4400,
250
4600,
251
4650,
252
5000,
253
rm5200,
254
rm5230,
255
rm5231,
256
rm5261,
257
rm5721,
258
vr5400,
259
vr5500,
260
6000,
261
rm7000,
262
8000,
263
rm9000,
264
10000,
265
12000,
266
14000,
267
16000,
268
4kc,
269
4km,
270
4kp,
271
4ksc,
272
4kec,
273
4kem,
274
4kep,
275
4ksd,
276
m4k,
277
m4kp,
278
24kc,
279
24kf2_1,
280
24kf,
281
24kf1_1,
282
24kec,
283
24kef2_1,
284
24kef,
285
24kef1_1,
286
34kc,
287
34kf2_1,
288
34kf,
289
34kf1_1,
290
74kc,
291
74kf2_1,
292
74kf,
293
74kf1_1,
294
74kf3_2,
295
1004kc,
296
1004kf2_1,
297
1004kf,
298
1004kf1_1,
299
5kc,
300
5kf,
301
20kc,
302
25kf,
303
sb1,
304
sb1a,
305
loongson2e,
306
loongson2f,
307
loongson3a,
308
octeon,
309
xlr
310
@end quotation
311
 
312
For compatibility reasons, @samp{@var{n}x} and @samp{@var{b}fx} are
313
accepted as synonyms for @samp{@var{n}f1_1}.  These values are
314
deprecated.
315
 
316
@item -mtune=@var{cpu}
317
Schedule and tune for a particular MIPS cpu.  Valid @var{cpu} values are
318
identical to @samp{-march=@var{cpu}}.
319
 
320
@item -mabi=@var{abi}
321
Record which ABI the source code uses.  The recognized arguments
322
are: @samp{32}, @samp{n32}, @samp{o64}, @samp{64} and @samp{eabi}.
323
 
324
@item -msym32
325
@itemx -mno-sym32
326
@cindex -msym32
327
@cindex -mno-sym32
328
Equivalent to adding @code{.set sym32} or @code{.set nosym32} to
329
the beginning of the assembler input.  @xref{MIPS symbol sizes}.
330
 
331
@cindex @code{-nocpp} ignored (MIPS)
332
@item -nocpp
333
This option is ignored.  It is accepted for command-line compatibility with
334
other assemblers, which use it to turn off C style preprocessing.  With
335
@sc{gnu} @code{@value{AS}}, there is no need for @samp{-nocpp}, because the
336
@sc{gnu} assembler itself never runs the C preprocessor.
337
 
338
@item -msoft-float
339
@itemx -mhard-float
340
Disable or enable floating-point instructions.  Note that by default
341
floating-point instructions are always allowed even with CPU targets
342
that don't have support for these instructions.
343
 
344
@item -msingle-float
345
@itemx -mdouble-float
346
Disable or enable double-precision floating-point operations.  Note
347
that by default double-precision floating-point operations are always
348
allowed even with CPU targets that don't have support for these
349
operations.
350
 
351
@item --construct-floats
352
@itemx --no-construct-floats
353
The @code{--no-construct-floats} option disables the construction of
354
double width floating point constants by loading the two halves of the
355
value into the two single width floating point registers that make up
356
the double width register.  This feature is useful if the processor
357
support the FR bit in its status  register, and this bit is known (by
358
the programmer) to be set.  This bit prevents the aliasing of the double
359
width register by the single width registers.
360
 
361
By default @code{--construct-floats} is selected, allowing construction
362
of these floating point constants.
363
 
364
@item --trap
365
@itemx --no-break
366
@c FIXME!  (1) reflect these options (next item too) in option summaries;
367
@c         (2) stop teasing, say _which_ instructions expanded _how_.
368
@code{@value{AS}} automatically macro expands certain division and
369
multiplication instructions to check for overflow and division by zero.  This
370
option causes @code{@value{AS}} to generate code to take a trap exception
371
rather than a break exception when an error is detected.  The trap instructions
372
are only supported at Instruction Set Architecture level 2 and higher.
373
 
374
@item --break
375
@itemx --no-trap
376
Generate code to take a break exception rather than a trap exception when an
377
error is detected.  This is the default.
378
 
379
@item -mpdr
380
@itemx -mno-pdr
381
Control generation of @code{.pdr} sections.  Off by default on IRIX, on
382
elsewhere.
383
 
384
@item -mshared
385
@itemx -mno-shared
386
When generating code using the Unix calling conventions (selected by
387
@samp{-KPIC} or @samp{-mcall_shared}), gas will normally generate code
388
which can go into a shared library.  The @samp{-mno-shared} option
389
tells gas to generate code which uses the calling convention, but can
390
not go into a shared library.  The resulting code is slightly more
391
efficient.  This option only affects the handling of the
392
@samp{.cpload} and @samp{.cpsetup} pseudo-ops.
393
@end table
394
 
395
@node MIPS Object
396
@section MIPS ECOFF object code
397
 
398
@cindex ECOFF sections
399
@cindex MIPS ECOFF sections
400
Assembling for a @sc{mips} @sc{ecoff} target supports some additional sections
401
besides the usual @code{.text}, @code{.data} and @code{.bss}.  The
402
additional sections are @code{.rdata}, used for read-only data,
403
@code{.sdata}, used for small data, and @code{.sbss}, used for small
404
common objects.
405
 
406
@cindex small objects, MIPS ECOFF
407
@cindex @code{gp} register, MIPS
408
When assembling for @sc{ecoff}, the assembler uses the @code{$gp} (@code{$28})
409
register to form the address of a ``small object''.  Any object in the
410
@code{.sdata} or @code{.sbss} sections is considered ``small'' in this sense.
411
For external objects, or for objects in the @code{.bss} section, you can use
412
the @code{@value{GCC}} @samp{-G} option to control the size of objects addressed via
413
@code{$gp}; the default value is 8, meaning that a reference to any object
414
eight bytes or smaller uses @code{$gp}.  Passing @samp{-G 0} to
415
@code{@value{AS}} prevents it from using the @code{$gp} register on the basis
416
of object size (but the assembler uses @code{$gp} for objects in @code{.sdata}
417
or @code{sbss} in any case).  The size of an object in the @code{.bss} section
418
is set by the @code{.comm} or @code{.lcomm} directive that defines it.  The
419
size of an external object may be set with the @code{.extern} directive.  For
420
example, @samp{.extern sym,4} declares that the object at @code{sym} is 4 bytes
421
in length, whie leaving @code{sym} otherwise undefined.
422
 
423
Using small @sc{ecoff} objects requires linker support, and assumes that the
424
@code{$gp} register is correctly initialized (normally done automatically by
425
the startup code).  @sc{mips} @sc{ecoff} assembly code must not modify the
426
@code{$gp} register.
427
 
428
@node MIPS Stabs
429
@section Directives for debugging information
430
 
431
@cindex MIPS debugging directives
432
@sc{mips} @sc{ecoff} @code{@value{AS}} supports several directives used for
433
generating debugging information which are not support by traditional @sc{mips}
434
assemblers.  These are @code{.def}, @code{.endef}, @code{.dim}, @code{.file},
435
@code{.scl}, @code{.size}, @code{.tag}, @code{.type}, @code{.val},
436
@code{.stabd}, @code{.stabn}, and @code{.stabs}.  The debugging information
437
generated by the three @code{.stab} directives can only be read by @sc{gdb},
438
not by traditional @sc{mips} debuggers (this enhancement is required to fully
439
support C++ debugging).  These directives are primarily used by compilers, not
440
assembly language programmers!
441
 
442
@node MIPS symbol sizes
443
@section Directives to override the size of symbols
444
 
445
@cindex @code{.set sym32}
446
@cindex @code{.set nosym32}
447
The n64 ABI allows symbols to have any 64-bit value.  Although this
448
provides a great deal of flexibility, it means that some macros have
449
much longer expansions than their 32-bit counterparts.  For example,
450
the non-PIC expansion of @samp{dla $4,sym} is usually:
451
 
452
@smallexample
453
lui     $4,%highest(sym)
454
lui     $1,%hi(sym)
455
daddiu  $4,$4,%higher(sym)
456
daddiu  $1,$1,%lo(sym)
457
dsll32  $4,$4,0
458
daddu   $4,$4,$1
459
@end smallexample
460
 
461
whereas the 32-bit expansion is simply:
462
 
463
@smallexample
464
lui     $4,%hi(sym)
465
daddiu  $4,$4,%lo(sym)
466
@end smallexample
467
 
468
n64 code is sometimes constructed in such a way that all symbolic
469
constants are known to have 32-bit values, and in such cases, it's
470
preferable to use the 32-bit expansion instead of the 64-bit
471
expansion.
472
 
473
You can use the @code{.set sym32} directive to tell the assembler
474
that, from this point on, all expressions of the form
475
@samp{@var{symbol}} or @samp{@var{symbol} + @var{offset}}
476
have 32-bit values.  For example:
477
 
478
@smallexample
479
.set sym32
480
dla     $4,sym
481
lw      $4,sym+16
482
sw      $4,sym+0x8000($4)
483
@end smallexample
484
 
485
will cause the assembler to treat @samp{sym}, @code{sym+16} and
486
@code{sym+0x8000} as 32-bit values.  The handling of non-symbolic
487
addresses is not affected.
488
 
489
The directive @code{.set nosym32} ends a @code{.set sym32} block and
490
reverts to the normal behavior.  It is also possible to change the
491
symbol size using the command-line options @option{-msym32} and
492
@option{-mno-sym32}.
493
 
494
These options and directives are always accepted, but at present,
495
they have no effect for anything other than n64.
496
 
497
@node MIPS ISA
498
@section Directives to override the ISA level
499
 
500
@cindex MIPS ISA override
501
@kindex @code{.set mips@var{n}}
502
@sc{gnu} @code{@value{AS}} supports an additional directive to change
503
the @sc{mips} Instruction Set Architecture level on the fly: @code{.set
504
mips@var{n}}.  @var{n} should be a number from 0 to 5, or 32, 32r2, 64
505
or 64r2.
506
The values other than 0 make the assembler accept instructions
507
for the corresponding @sc{isa} level, from that point on in the
508
assembly.  @code{.set mips@var{n}} affects not only which instructions
509
are permitted, but also how certain macros are expanded.  @code{.set
510
mips0} restores the @sc{isa} level to its original level: either the
511
level you selected with command line options, or the default for your
512
configuration.  You can use this feature to permit specific @sc{mips3}
513
instructions while assembling in 32 bit mode.  Use this directive with
514
care!
515
 
516
@cindex MIPS CPU override
517
@kindex @code{.set arch=@var{cpu}}
518
The @code{.set arch=@var{cpu}} directive provides even finer control.
519
It changes the effective CPU target and allows the assembler to use
520
instructions specific to a particular CPU.  All CPUs supported by the
521
@samp{-march} command line option are also selectable by this directive.
522
The original value is restored by @code{.set arch=default}.
523
 
524
The directive @code{.set mips16} puts the assembler into MIPS 16 mode,
525
in which it will assemble instructions for the MIPS 16 processor.  Use
526
@code{.set nomips16} to return to normal 32 bit mode.
527
 
528
Traditional @sc{mips} assemblers do not support this directive.
529
 
530
@node MIPS autoextend
531
@section Directives for extending MIPS 16 bit instructions
532
 
533
@kindex @code{.set autoextend}
534
@kindex @code{.set noautoextend}
535
By default, MIPS 16 instructions are automatically extended to 32 bits
536
when necessary.  The directive @code{.set noautoextend} will turn this
537
off.  When @code{.set noautoextend} is in effect, any 32 bit instruction
538
must be explicitly extended with the @code{.e} modifier (e.g.,
539
@code{li.e $4,1000}).  The directive @code{.set autoextend} may be used
540
to once again automatically extend instructions when necessary.
541
 
542
This directive is only meaningful when in MIPS 16 mode.  Traditional
543
@sc{mips} assemblers do not support this directive.
544
 
545
@node MIPS insn
546
@section Directive to mark data as an instruction
547
 
548
@kindex @code{.insn}
549
The @code{.insn} directive tells @code{@value{AS}} that the following
550
data is actually instructions.  This makes a difference in MIPS 16 mode:
551
when loading the address of a label which precedes instructions,
552
@code{@value{AS}} automatically adds 1 to the value, so that jumping to
553
the loaded address will do the right thing.
554
 
555
@kindex @code{.global}
556
The @code{.global} and @code{.globl} directives supported by
557
@code{@value{AS}} will by default mark the symbol as pointing to a
558
region of data not code.  This means that, for example, any
559
instructions following such a symbol will not be disassembled by
560
@code{objdump} as it will regard them as data.  To change this
561
behaviour an optional section name can be placed after the symbol name
562
in the @code{.global} directive.  If this section exists and is known
563
to be a code section, then the symbol will be marked as poiting at
564
code not data.  Ie the syntax for the directive is:
565
 
566
  @code{.global @var{symbol}[ @var{section}][, @var{symbol}[ @var{section}]] ...},
567
 
568
Here is a short example:
569
 
570
@example
571
        .global foo .text, bar, baz .data
572
foo:
573
        nop
574
bar:
575
        .word 0x0
576
baz:
577
        .word 0x1
578
 
579
@end example
580
 
581
@node MIPS option stack
582
@section Directives to save and restore options
583
 
584
@cindex MIPS option stack
585
@kindex @code{.set push}
586
@kindex @code{.set pop}
587
The directives @code{.set push} and @code{.set pop} may be used to save
588
and restore the current settings for all the options which are
589
controlled by @code{.set}.  The @code{.set push} directive saves the
590
current settings on a stack.  The @code{.set pop} directive pops the
591
stack and restores the settings.
592
 
593
These directives can be useful inside an macro which must change an
594
option such as the ISA level or instruction reordering but does not want
595
to change the state of the code which invoked the macro.
596
 
597
Traditional @sc{mips} assemblers do not support these directives.
598
 
599
@node MIPS ASE instruction generation overrides
600
@section Directives to control generation of MIPS ASE instructions
601
 
602
@cindex MIPS MIPS-3D instruction generation override
603
@kindex @code{.set mips3d}
604
@kindex @code{.set nomips3d}
605
The directive @code{.set mips3d} makes the assembler accept instructions
606
from the MIPS-3D Application Specific Extension from that point on
607
in the assembly.  The @code{.set nomips3d} directive prevents MIPS-3D
608
instructions from being accepted.
609
 
610
@cindex SmartMIPS instruction generation override
611
@kindex @code{.set smartmips}
612
@kindex @code{.set nosmartmips}
613
The directive @code{.set smartmips} makes the assembler accept
614
instructions from the SmartMIPS Application Specific Extension to the
615
MIPS32 @sc{isa} from that point on in the assembly.  The
616
@code{.set nosmartmips} directive prevents SmartMIPS instructions from
617
being accepted.
618
 
619
@cindex MIPS MDMX instruction generation override
620
@kindex @code{.set mdmx}
621
@kindex @code{.set nomdmx}
622
The directive @code{.set mdmx} makes the assembler accept instructions
623
from the MDMX Application Specific Extension from that point on
624
in the assembly.  The @code{.set nomdmx} directive prevents MDMX
625
instructions from being accepted.
626
 
627
@cindex MIPS DSP Release 1 instruction generation override
628
@kindex @code{.set dsp}
629
@kindex @code{.set nodsp}
630
The directive @code{.set dsp} makes the assembler accept instructions
631
from the DSP Release 1 Application Specific Extension from that point
632
on in the assembly.  The @code{.set nodsp} directive prevents DSP
633
Release 1 instructions from being accepted.
634
 
635
@cindex MIPS DSP Release 2 instruction generation override
636
@kindex @code{.set dspr2}
637
@kindex @code{.set nodspr2}
638
The directive @code{.set dspr2} makes the assembler accept instructions
639
from the DSP Release 2 Application Specific Extension from that point
640
on in the assembly.  This dirctive implies @code{.set dsp}.  The
641
@code{.set nodspr2} directive prevents DSP Release 2 instructions from
642
being accepted.
643
 
644
@cindex MIPS MT instruction generation override
645
@kindex @code{.set mt}
646
@kindex @code{.set nomt}
647
The directive @code{.set mt} makes the assembler accept instructions
648
from the MT Application Specific Extension from that point on
649
in the assembly.  The @code{.set nomt} directive prevents MT
650
instructions from being accepted.
651
 
652
Traditional @sc{mips} assemblers do not support these directives.
653
 
654
@node MIPS floating-point
655
@section Directives to override floating-point options
656
 
657
@cindex Disable floating-point instructions
658
@kindex @code{.set softfloat}
659
@kindex @code{.set hardfloat}
660
The directives @code{.set softfloat} and @code{.set hardfloat} provide
661
finer control of disabling and enabling float-point instructions.
662
These directives always override the default (that hard-float
663
instructions are accepted) or the command-line options
664
(@samp{-msoft-float} and @samp{-mhard-float}).
665
 
666
@cindex Disable single-precision floating-point operations
667
@kindex @code{.set singlefloat}
668
@kindex @code{.set doublefloat}
669
The directives @code{.set singlefloat} and @code{.set doublefloat}
670
provide finer control of disabling and enabling double-precision
671
float-point operations.  These directives always override the default
672
(that double-precision operations are accepted) or the command-line
673
options (@samp{-msingle-float} and @samp{-mdouble-float}).
674
 
675
Traditional @sc{mips} assemblers do not support these directives.
676
 
677
@node MIPS Syntax
678
@section Syntactical considerations for the MIPS assembler
679
@menu
680
* MIPS-Chars::                Special Characters
681
@end menu
682
 
683
@node MIPS-Chars
684
@subsection Special Characters
685
 
686
@cindex line comment character, MIPS
687
@cindex MIPS line comment character
688
The presence of a @samp{#} on a line indicates the start of a comment
689
that extends to the end of the current line.
690
 
691
If a @samp{#} appears as the first character of a line, the whole line
692
is treated as a comment, but in this case the line can also be a
693
logical line number directive (@pxref{Comments}) or a
694
preprocessor control command (@pxref{Preprocessing}).
695
 
696
@cindex line separator, MIPS
697
@cindex statement separator, MIPS
698
@cindex MIPS line separator
699
The @samp{;} character can be used to separate statements on the same
700
line.

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