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<h4 class="subsection">9.27.1 Assembler options</h4>

<p>The MIPS configurations of <span class="sc">gnu</span> <code>as</code> support these
special options:

     
<a name="index-g_t_0040code_007b_002dG_007d-option-_0028MIPS_0029-1555"></a>
<dl><dt><code>-G </code><var>num</var><dd>Set the &ldquo;small data&rdquo; limit to <var>n</var> bytes.  The default limit is 8 bytes. 
See <a href="MIPS-Small-Data.html#MIPS-Small-Data">Controlling the use of small data accesses</a>.

     <p><a name="index-g_t_0040code_007b_002dEB_007d-option-_0028MIPS_0029-1556"></a><a name="index-g_t_0040code_007b_002dEL_007d-option-_0028MIPS_0029-1557"></a><a name="index-MIPS-big_002dendian-output-1558"></a><a name="index-MIPS-little_002dendian-output-1559"></a><a name="index-big_002dendian-output_002c-MIPS-1560"></a><a name="index-little_002dendian-output_002c-MIPS-1561"></a><br><dt><code>-EB</code><dt><code>-EL</code><dd>Any MIPS configuration of <code>as</code> can select big-endian or
little-endian output at run time (unlike the other <span class="sc">gnu</span> development
tools, which must be configured for one or the other).  Use &lsquo;<samp><span class="samp">-EB</span></samp>&rsquo;
to select big-endian output, and &lsquo;<samp><span class="samp">-EL</span></samp>&rsquo; for little-endian.

     <br><dt><code>-KPIC</code><dd><a name="index-PIC-selection_002c-MIPS-1562"></a><a name="index-g_t_0040option_007b_002dKPIC_007d-option_002c-MIPS-1563"></a>Generate SVR4-style PIC.  This option tells the assembler to generate
SVR4-style position-independent macro expansions.  It also tells the
assembler to mark the output file as PIC.

     <br><dt><code>-mvxworks-pic</code><dd><a name="index-g_t_0040option_007b_002dmvxworks_002dpic_007d-option_002c-MIPS-1564"></a>Generate VxWorks PIC.  This option tells the assembler to generate
VxWorks-style position-independent macro expansions.

     <p><a name="index-MIPS-architecture-options-1565"></a><br><dt><code>-mips1</code><dt><code>-mips2</code><dt><code>-mips3</code><dt><code>-mips4</code><dt><code>-mips5</code><dt><code>-mips32</code><dt><code>-mips32r2</code><dt><code>-mips32r3</code><dt><code>-mips32r5</code><dt><code>-mips32r6</code><dt><code>-mips64</code><dt><code>-mips64r2</code><dt><code>-mips64r3</code><dt><code>-mips64r5</code><dt><code>-mips64r6</code><dd>Generate code for a particular MIPS Instruction Set Architecture level. 
&lsquo;<samp><span class="samp">-mips1</span></samp>&rsquo; corresponds to the R2000 and R3000 processors,
&lsquo;<samp><span class="samp">-mips2</span></samp>&rsquo; to the R6000 processor, &lsquo;<samp><span class="samp">-mips3</span></samp>&rsquo; to the
R4000 processor, and &lsquo;<samp><span class="samp">-mips4</span></samp>&rsquo; to the R8000 and R10000 processors. 
&lsquo;<samp><span class="samp">-mips5</span></samp>&rsquo;, &lsquo;<samp><span class="samp">-mips32</span></samp>&rsquo;, &lsquo;<samp><span class="samp">-mips32r2</span></samp>&rsquo;, &lsquo;<samp><span class="samp">-mips32r3</span></samp>&rsquo;,
&lsquo;<samp><span class="samp">-mips32r5</span></samp>&rsquo;, &lsquo;<samp><span class="samp">-mips32r6</span></samp>&rsquo;, &lsquo;<samp><span class="samp">-mips64</span></samp>&rsquo;, &lsquo;<samp><span class="samp">-mips64r2</span></samp>&rsquo;,
&lsquo;<samp><span class="samp">-mips64r3</span></samp>&rsquo;, &lsquo;<samp><span class="samp">-mips64r5</span></samp>&rsquo;, and &lsquo;<samp><span class="samp">-mips64r6</span></samp>&rsquo; correspond to
generic MIPS V, MIPS32, MIPS32 Release 2, MIPS32 Release 3, MIPS32
Release 5, MIPS32 Release 6, MIPS64, and MIPS64 Release 2, MIPS64
Release 3, MIPS64 Release 5, and MIPS64 Release 6 ISA processors,
respectively.  You can also switch instruction sets during the assembly;
see <a href="MIPS-ISA.html#MIPS-ISA">Directives to override the ISA level</a>.

     <br><dt><code>-mgp32</code><dt><code>-mfp32</code><dd>Some macros have different expansions for 32-bit and 64-bit registers. 
The register sizes are normally inferred from the ISA and ABI, but these
flags force a certain group of registers to be treated as 32 bits wide at
all times.  &lsquo;<samp><span class="samp">-mgp32</span></samp>&rsquo; controls the size of general-purpose registers
and &lsquo;<samp><span class="samp">-mfp32</span></samp>&rsquo; controls the size of floating-point registers.

     <p>The <code>.set gp=32</code> and <code>.set fp=32</code> directives allow the size
of registers to be changed for parts of an object. The default value is
restored by <code>.set gp=default</code> and <code>.set fp=default</code>.

     <p>On some MIPS variants there is a 32-bit mode flag; when this flag is
set, 64-bit instructions generate a trap.  Also, some 32-bit OSes only
save the 32-bit registers on a context switch, so it is essential never
to use the 64-bit registers.

     <br><dt><code>-mgp64</code><dt><code>-mfp64</code><dd>Assume that 64-bit registers are available.  This is provided in the
interests of symmetry with &lsquo;<samp><span class="samp">-mgp32</span></samp>&rsquo; and &lsquo;<samp><span class="samp">-mfp32</span></samp>&rsquo;.

     <p>The <code>.set gp=64</code> and <code>.set fp=64</code> directives allow the size
of registers to be changed for parts of an object. The default value is
restored by <code>.set gp=default</code> and <code>.set fp=default</code>.

     <br><dt><code>-mfpxx</code><dd>Make no assumptions about whether 32-bit or 64-bit floating-point
registers are available. This is provided to support having modules
compatible with either &lsquo;<samp><span class="samp">-mfp32</span></samp>&rsquo; or &lsquo;<samp><span class="samp">-mfp64</span></samp>&rsquo;. This option can
only be used with MIPS II and above.

     <p>The <code>.set fp=xx</code> directive allows a part of an object to be marked
as not making assumptions about 32-bit or 64-bit FP registers.  The
default value is restored by <code>.set fp=default</code>.

     <br><dt><code>-modd-spreg</code><dt><code>-mno-odd-spreg</code><dd>Enable use of floating-point operations on odd-numbered single-precision
registers when supported by the ISA.  &lsquo;<samp><span class="samp">-mfpxx</span></samp>&rsquo; implies
&lsquo;<samp><span class="samp">-mno-odd-spreg</span></samp>&rsquo;, otherwise the default is &lsquo;<samp><span class="samp">-modd-spreg</span></samp>&rsquo;

     <br><dt><code>-mips16</code><dt><code>-no-mips16</code><dd>Generate code for the MIPS 16 processor.  This is equivalent to putting
<code>.module mips16</code> at the start of the assembly file.  &lsquo;<samp><span class="samp">-no-mips16</span></samp>&rsquo;
turns off this option.

     <br><dt><code>-mmips16e2</code><dt><code>-mno-mips16e2</code><dd>Enable the use of MIPS16e2 instructions in MIPS16 mode.  This is equivalent
to putting <code>.module mips16e2</code> at the start of the assembly file. 
&lsquo;<samp><span class="samp">-mno-mips16e2</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mmicromips</code><dt><code>-mno-micromips</code><dd>Generate code for the microMIPS processor.  This is equivalent to putting
<code>.module micromips</code> at the start of the assembly file. 
&lsquo;<samp><span class="samp">-mno-micromips</span></samp>&rsquo; turns off this option.  This is equivalent to putting
<code>.module nomicromips</code> at the start of the assembly file.

     <br><dt><code>-msmartmips</code><dt><code>-mno-smartmips</code><dd>Enables the SmartMIPS extensions to the MIPS32 instruction set, which
provides a number of new instructions which target smartcard and
cryptographic applications.  This is equivalent to putting
<code>.module smartmips</code> at the start of the assembly file. 
&lsquo;<samp><span class="samp">-mno-smartmips</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mips3d</code><dt><code>-no-mips3d</code><dd>Generate code for the MIPS-3D Application Specific Extension. 
This tells the assembler to accept MIPS-3D instructions. 
&lsquo;<samp><span class="samp">-no-mips3d</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mdmx</code><dt><code>-no-mdmx</code><dd>Generate code for the MDMX Application Specific Extension. 
This tells the assembler to accept MDMX instructions. 
&lsquo;<samp><span class="samp">-no-mdmx</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mdsp</code><dt><code>-mno-dsp</code><dd>Generate code for the DSP Release 1 Application Specific Extension. 
This tells the assembler to accept DSP Release 1 instructions. 
&lsquo;<samp><span class="samp">-mno-dsp</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mdspr2</code><dt><code>-mno-dspr2</code><dd>Generate code for the DSP Release 2 Application Specific Extension. 
This option implies &lsquo;<samp><span class="samp">-mdsp</span></samp>&rsquo;. 
This tells the assembler to accept DSP Release 2 instructions. 
&lsquo;<samp><span class="samp">-mno-dspr2</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mdspr3</code><dt><code>-mno-dspr3</code><dd>Generate code for the DSP Release 3 Application Specific Extension. 
This option implies &lsquo;<samp><span class="samp">-mdsp</span></samp>&rsquo; and &lsquo;<samp><span class="samp">-mdspr2</span></samp>&rsquo;. 
This tells the assembler to accept DSP Release 3 instructions. 
&lsquo;<samp><span class="samp">-mno-dspr3</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mmt</code><dt><code>-mno-mt</code><dd>Generate code for the MT Application Specific Extension. 
This tells the assembler to accept MT instructions. 
&lsquo;<samp><span class="samp">-mno-mt</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mmcu</code><dt><code>-mno-mcu</code><dd>Generate code for the MCU Application Specific Extension. 
This tells the assembler to accept MCU instructions. 
&lsquo;<samp><span class="samp">-mno-mcu</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mmsa</code><dt><code>-mno-msa</code><dd>Generate code for the MIPS SIMD Architecture Extension. 
This tells the assembler to accept MSA instructions. 
&lsquo;<samp><span class="samp">-mno-msa</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mxpa</code><dt><code>-mno-xpa</code><dd>Generate code for the MIPS eXtended Physical Address (XPA) Extension. 
This tells the assembler to accept XPA instructions. 
&lsquo;<samp><span class="samp">-mno-xpa</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mvirt</code><dt><code>-mno-virt</code><dd>Generate code for the Virtualization Application Specific Extension. 
This tells the assembler to accept Virtualization instructions. 
&lsquo;<samp><span class="samp">-mno-virt</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mcrc</code><dt><code>-mno-crc</code><dd>Generate code for the cyclic redundancy check (CRC) Application Specific
Extension.  This tells the assembler to accept CRC instructions. 
&lsquo;<samp><span class="samp">-mno-crc</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mginv</code><dt><code>-mno-ginv</code><dd>Generate code for the Global INValidate (GINV) Application Specific
Extension.  This tells the assembler to accept GINV instructions. 
&lsquo;<samp><span class="samp">-mno-ginv</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mloongson-mmi</code><dt><code>-mno-loongson-mmi</code><dd>Generate code for the Loongson MultiMedia extensions Instructions (MMI)
Application Specific Extension.  This tells the assembler to accept MMI
instructions. 
&lsquo;<samp><span class="samp">-mno-loongson-mmi</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mloongson-cam</code><dt><code>-mno-loongson-cam</code><dd>Generate code for the Loongson Content Address Memory (CAM)
Application Specific Extension.  This tells the assembler to accept CAM
instructions. 
&lsquo;<samp><span class="samp">-mno-loongson-cam</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mloongson-ext</code><dt><code>-mno-loongson-ext</code><dd>Generate code for the Loongson EXTensions (EXT) instructions
Application Specific Extension.  This tells the assembler to accept EXT
instructions. 
&lsquo;<samp><span class="samp">-mno-loongson-ext</span></samp>&rsquo; turns off this option.

     <br><dt><code>-mloongson-ext2</code><dt><code>-mno-loongson-ext2</code><dd>Generate code for the Loongson EXTensions R2 (EXT2) instructions
Application Specific Extension.  This tells the assembler to accept EXT2
instructions. 
&lsquo;<samp><span class="samp">-mno-loongson-ext2</span></samp>&rsquo; turns off this option.

     <br><dt><code>-minsn32</code><dt><code>-mno-insn32</code><dd>Only use 32-bit instruction encodings when generating code for the
microMIPS processor.  This option inhibits the use of any 16-bit
instructions.  This is equivalent to putting <code>.set insn32</code> at
the start of the assembly file.  &lsquo;<samp><span class="samp">-mno-insn32</span></samp>&rsquo; turns off this
option.  This is equivalent to putting <code>.set noinsn32</code> at the
start of the assembly file.  By default &lsquo;<samp><span class="samp">-mno-insn32</span></samp>&rsquo; is
selected, allowing all instructions to be used.

     <br><dt><code>-mfix7000</code><dt><code>-mno-fix7000</code><dd>Cause nops to be inserted if the read of the destination register
of an mfhi or mflo instruction occurs in the following two instructions.

     <br><dt><code>-mfix-rm7000</code><dt><code>-mno-fix-rm7000</code><dd>Cause nops to be inserted if a dmult or dmultu instruction is
followed by a load instruction.

     <br><dt><code>-mfix-loongson2f-jump</code><dt><code>-mno-fix-loongson2f-jump</code><dd>Eliminate instruction fetch from outside 256M region to work around the
Loongson2F &lsquo;<samp><span class="samp">jump</span></samp>&rsquo; instructions.  Without it, under extreme cases,
the kernel may crash.  The issue has been solved in latest processor
batches, but this fix has no side effect to them.

     <br><dt><code>-mfix-loongson2f-nop</code><dt><code>-mno-fix-loongson2f-nop</code><dd>Replace nops by <code>or at,at,zero</code> to work around the Loongson2F
&lsquo;<samp><span class="samp">nop</span></samp>&rsquo; errata.  Without it, under extreme cases, the CPU might
deadlock.  The issue has been solved in later Loongson2F batches, but
this fix has no side effect to them.

     <br><dt><code>-mfix-loongson3-llsc</code><dt><code>-mno-fix-loongson3-llsc</code><dd>Insert &lsquo;<samp><span class="samp">sync</span></samp>&rsquo; before &lsquo;<samp><span class="samp">ll</span></samp>&rsquo; and &lsquo;<samp><span class="samp">lld</span></samp>&rsquo; to work around
Loongson3 LLSC errata.  Without it, under extrame cases, the CPU might
deadlock. The default can be controlled by the
<samp><span class="option">--enable-mips-fix-loongson3-llsc=[yes|no]</span></samp> configure option.

     <br><dt><code>-mfix-vr4120</code><dt><code>-mno-fix-vr4120</code><dd>Insert nops to work around certain VR4120 errata.  This option is
intended to be used on GCC-generated code: it is not designed to catch
all problems in hand-written assembler code.

     <br><dt><code>-mfix-vr4130</code><dt><code>-mno-fix-vr4130</code><dd>Insert nops to work around the VR4130 &lsquo;<samp><span class="samp">mflo</span></samp>&rsquo;/&lsquo;<samp><span class="samp">mfhi</span></samp>&rsquo; errata.

     <br><dt><code>-mfix-24k</code><dt><code>-mno-fix-24k</code><dd>Insert nops to work around the 24K &lsquo;<samp><span class="samp">eret</span></samp>&rsquo;/&lsquo;<samp><span class="samp">deret</span></samp>&rsquo; errata.

     <br><dt><code>-mfix-cn63xxp1</code><dt><code>-mno-fix-cn63xxp1</code><dd>Replace <code>pref</code> hints 0 - 4 and 6 - 24 with hint 28 to work around
certain CN63XXP1 errata.

     <br><dt><code>-mfix-r5900</code><dt><code>-mno-fix-r5900</code><dd>Do not attempt to schedule the preceding instruction into the delay slot
of a branch instruction placed at the end of a short loop of six
instructions or fewer and always schedule a <code>nop</code> instruction there
instead.  The short loop bug under certain conditions causes loops to
execute only once or twice, due to a hardware bug in the R5900 chip.

     <br><dt><code>-m4010</code><dt><code>-no-m4010</code><dd>Generate code for the LSI R4010 chip.  This tells the assembler to
accept the R4010-specific instructions (&lsquo;<samp><span class="samp">addciu</span></samp>&rsquo;, &lsquo;<samp><span class="samp">ffc</span></samp>&rsquo;,
etc.), and to not schedule &lsquo;<samp><span class="samp">nop</span></samp>&rsquo; instructions around accesses to
the &lsquo;<samp><span class="samp">HI</span></samp>&rsquo; and &lsquo;<samp><span class="samp">LO</span></samp>&rsquo; registers.  &lsquo;<samp><span class="samp">-no-m4010</span></samp>&rsquo; turns off this
option.

     <br><dt><code>-m4650</code><dt><code>-no-m4650</code><dd>Generate code for the MIPS R4650 chip.  This tells the assembler to accept
the &lsquo;<samp><span class="samp">mad</span></samp>&rsquo; and &lsquo;<samp><span class="samp">madu</span></samp>&rsquo; instruction, and to not schedule &lsquo;<samp><span class="samp">nop</span></samp>&rsquo;
instructions around accesses to the &lsquo;<samp><span class="samp">HI</span></samp>&rsquo; and &lsquo;<samp><span class="samp">LO</span></samp>&rsquo; registers. 
&lsquo;<samp><span class="samp">-no-m4650</span></samp>&rsquo; turns off this option.

     <br><dt><code>-m3900</code><dt><code>-no-m3900</code><dt><code>-m4100</code><dt><code>-no-m4100</code><dd>For each option &lsquo;<samp><span class="samp">-m</span><var>nnnn</var></samp>&rsquo;, generate code for the MIPS
R<var>nnnn</var> chip.  This tells the assembler to accept instructions
specific to that chip, and to schedule for that chip's hazards.

     <br><dt><code>-march=</code><var>cpu</var><dd>Generate code for a particular MIPS CPU.  It is exactly equivalent to
&lsquo;<samp><span class="samp">-m</span><var>cpu</var></samp>&rsquo;, except that there are more value of <var>cpu</var>
understood.  Valid <var>cpu</var> value are:

     <blockquote>
2000,
3000,
3900,
4000,
4010,
4100,
4111,
vr4120,
vr4130,
vr4181,
4300,
4400,
4600,
4650,
5000,
rm5200,
rm5230,
rm5231,
rm5261,
rm5721,
vr5400,
vr5500,
6000,
rm7000,
8000,
rm9000,
10000,
12000,
14000,
16000,
4kc,
4km,
4kp,
4ksc,
4kec,
4kem,
4kep,
4ksd,
m4k,
m4kp,
m14k,
m14kc,
m14ke,
m14kec,
24kc,
24kf2_1,
24kf,
24kf1_1,
24kec,
24kef2_1,
24kef,
24kef1_1,
34kc,
34kf2_1,
34kf,
34kf1_1,
34kn,
74kc,
74kf2_1,
74kf,
74kf1_1,
74kf3_2,
1004kc,
1004kf2_1,
1004kf,
1004kf1_1,
interaptiv,
interaptiv-mr2,
m5100,
m5101,
p5600,
5kc,
5kf,
20kc,
25kf,
sb1,
sb1a,
i6400,
i6500,
p6600,
loongson2e,
loongson2f,
gs464,
gs464e,
gs264e,
octeon,
octeon+,
octeon2,
octeon3,
xlr,
xlp
</blockquote>

     <p>For compatibility reasons, &lsquo;<samp><var>n</var><span class="samp">x</span></samp>&rsquo; and &lsquo;<samp><var>b</var><span class="samp">fx</span></samp>&rsquo; are
accepted as synonyms for &lsquo;<samp><var>n</var><span class="samp">f1_1</span></samp>&rsquo;.  These values are
deprecated.

     <br><dt><code>-mtune=</code><var>cpu</var><dd>Schedule and tune for a particular MIPS CPU.  Valid <var>cpu</var> values are
identical to &lsquo;<samp><span class="samp">-march=</span><var>cpu</var></samp>&rsquo;.

     <br><dt><code>-mabi=</code><var>abi</var><dd>Record which ABI the source code uses.  The recognized arguments
are: &lsquo;<samp><span class="samp">32</span></samp>&rsquo;, &lsquo;<samp><span class="samp">n32</span></samp>&rsquo;, &lsquo;<samp><span class="samp">o64</span></samp>&rsquo;, &lsquo;<samp><span class="samp">64</span></samp>&rsquo; and &lsquo;<samp><span class="samp">eabi</span></samp>&rsquo;.

     <br><dt><code>-msym32</code><dt><code>-mno-sym32</code><dd><a name="index-g_t_002dmsym32-1566"></a><a name="index-g_t_002dmno_002dsym32-1567"></a>Equivalent to adding <code>.set sym32</code> or <code>.set nosym32</code> to
the beginning of the assembler input.  See <a href="MIPS-Symbol-Sizes.html#MIPS-Symbol-Sizes">MIPS Symbol Sizes</a>.

     <p><a name="index-g_t_0040code_007b_002dnocpp_007d-ignored-_0028MIPS_0029-1568"></a><br><dt><code>-nocpp</code><dd>This option is ignored.  It is accepted for command-line compatibility with
other assemblers, which use it to turn off C style preprocessing.  With
<span class="sc">gnu</span> <code>as</code>, there is no need for &lsquo;<samp><span class="samp">-nocpp</span></samp>&rsquo;, because the
<span class="sc">gnu</span> assembler itself never runs the C preprocessor.

     <br><dt><code>-msoft-float</code><dt><code>-mhard-float</code><dd>Disable or enable floating-point instructions.  Note that by default
floating-point instructions are always allowed even with CPU targets
that don't have support for these instructions.

     <br><dt><code>-msingle-float</code><dt><code>-mdouble-float</code><dd>Disable or enable double-precision floating-point operations.  Note
that by default double-precision floating-point operations are always
allowed even with CPU targets that don't have support for these
operations.

     <br><dt><code>--construct-floats</code><dt><code>--no-construct-floats</code><dd>The <code>--no-construct-floats</code> option disables the construction of
double width floating point constants by loading the two halves of the
value into the two single width floating point registers that make up
the double width register.  This feature is useful if the processor
support the FR bit in its status  register, and this bit is known (by
the programmer) to be set.  This bit prevents the aliasing of the double
width register by the single width registers.

     <p>By default <code>--construct-floats</code> is selected, allowing construction
of these floating point constants.

     <br><dt><code>--relax-branch</code><dt><code>--no-relax-branch</code><dd>The &lsquo;<samp><span class="samp">--relax-branch</span></samp>&rsquo; option enables the relaxation of out-of-range
branches.  Any branches whose target cannot be reached directly are
converted to a small instruction sequence including an inverse-condition
branch to the physically next instruction, and a jump to the original
target is inserted between the two instructions.  In PIC code the jump
will involve further instructions for address calculation.

     <p>The <code>BC1ANY2F</code>, <code>BC1ANY2T</code>, <code>BC1ANY4F</code>, <code>BC1ANY4T</code>,
<code>BPOSGE32</code> and <code>BPOSGE64</code> instructions are excluded from
relaxation, because they have no complementing counterparts.  They could
be relaxed with the use of a longer sequence involving another branch,
however this has not been implemented and if their target turns out of
reach, they produce an error even if branch relaxation is enabled.

     <p>Also no MIPS16 branches are ever relaxed.

     <p>By default &lsquo;<samp><span class="samp">--no-relax-branch</span></samp>&rsquo; is selected, causing any out-of-range
branches to produce an error.

     <br><dt><code>-mignore-branch-isa</code><dt><code>-mno-ignore-branch-isa</code><dd>Ignore branch checks for invalid transitions between ISA modes.

     <p>The semantics of branches does not provide for an ISA mode switch, so in
most cases the ISA mode a branch has been encoded for has to be the same
as the ISA mode of the branch's target label.  If the ISA modes do not
match, then such a branch, if taken, will cause the ISA mode to remain
unchanged and instructions that follow will be executed in the wrong ISA
mode causing the program to misbehave or crash.

     <p>In the case of the <code>BAL</code> instruction it may be possible to relax
it to an equivalent <code>JALX</code> instruction so that the ISA mode is
switched at the run time as required.  For other branches no relaxation
is possible and therefore GAS has checks implemented that verify in
branch assembly that the two ISA modes match, and report an error
otherwise so that the problem with code can be diagnosed at the assembly
time rather than at the run time.

     <p>However some assembly code, including generated code produced by some
versions of GCC, may incorrectly include branches to data labels, which
appear to require a mode switch but are either dead or immediately
followed by valid instructions encoded for the same ISA the branch has
been encoded for.  While not strictly correct at the source level such
code will execute as intended, so to help with these cases
&lsquo;<samp><span class="samp">-mignore-branch-isa</span></samp>&rsquo; is supported which disables ISA mode checks
for branches.

     <p>By default &lsquo;<samp><span class="samp">-mno-ignore-branch-isa</span></samp>&rsquo; is selected, causing any invalid
branch requiring a transition between ISA modes to produce an error.

     <p><a name="index-g_t_0040option_007b_002dmnan_003d_007d-command_002dline-option_002c-MIPS-1569"></a><br><dt><code>-mnan=</code><var>encoding</var><dd>This option indicates whether the source code uses the IEEE 2008
NaN encoding (<samp><span class="option">-mnan=2008</span></samp>) or the original MIPS encoding
(<samp><span class="option">-mnan=legacy</span></samp>).  It is equivalent to adding a <code>.nan</code>
directive to the beginning of the source file.  See <a href="MIPS-NaN-Encodings.html#MIPS-NaN-Encodings">MIPS NaN Encodings</a>.

     <p><samp><span class="option">-mnan=legacy</span></samp> is the default if no <samp><span class="option">-mnan</span></samp> option or
<code>.nan</code> directive is used.

     <br><dt><code>--trap</code><dt><code>--no-break</code><dd><!-- FIXME!  (1) reflect these options (next item too) in option summaries; -->
<!-- (2) stop teasing, say _which_ instructions expanded _how_. -->
<code>as</code> automatically macro expands certain division and
multiplication instructions to check for overflow and division by zero.  This
option causes <code>as</code> to generate code to take a trap exception
rather than a break exception when an error is detected.  The trap instructions
are only supported at Instruction Set Architecture level 2 and higher.

     <br><dt><code>--break</code><dt><code>--no-trap</code><dd>Generate code to take a break exception rather than a trap exception when an
error is detected.  This is the default.

     <br><dt><code>-mpdr</code><dt><code>-mno-pdr</code><dd>Control generation of <code>.pdr</code> sections.  Off by default on IRIX, on
elsewhere.

     <br><dt><code>-mshared</code><dt><code>-mno-shared</code><dd>When generating code using the Unix calling conventions (selected by
&lsquo;<samp><span class="samp">-KPIC</span></samp>&rsquo; or &lsquo;<samp><span class="samp">-mcall_shared</span></samp>&rsquo;), gas will normally generate code
which can go into a shared library.  The &lsquo;<samp><span class="samp">-mno-shared</span></samp>&rsquo; option
tells gas to generate code which uses the calling convention, but can
not go into a shared library.  The resulting code is slightly more
efficient.  This option only affects the handling of the
&lsquo;<samp><span class="samp">.cpload</span></samp>&rsquo; and &lsquo;<samp><span class="samp">.cpsetup</span></samp>&rsquo; pseudo-ops. 
</dl>

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