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<title>Using the GNU Compiler Collection (GCC): PowerPC Function Attributes</title>
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<a name="PowerPC-Function-Attributes"></a>
<div class="header">
<p>
Next: <a href="RL78-Function-Attributes.html#RL78-Function-Attributes" accesskey="n" rel="next">RL78 Function Attributes</a>, Previous: <a href="Nvidia-PTX-Function-Attributes.html#Nvidia-PTX-Function-Attributes" accesskey="p" rel="prev">Nvidia PTX Function Attributes</a>, Up: <a href="Function-Attributes.html#Function-Attributes" accesskey="u" rel="up">Function Attributes</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="PowerPC-Function-Attributes-1"></a>
<h4 class="subsection">6.31.23 PowerPC Function Attributes</h4>
<p>These function attributes are supported by the PowerPC back end:
</p>
<dl compact="compact">
<dt><code>longcall</code></dt>
<dt><code>shortcall</code></dt>
<dd><a name="index-indirect-calls_002c-PowerPC"></a>
<a name="index-longcall-function-attribute_002c-PowerPC"></a>
<a name="index-shortcall-function-attribute_002c-PowerPC"></a>
<p>The <code>longcall</code> attribute
indicates that the function might be far away from the call site and
require a different (more expensive) calling sequence. The
<code>shortcall</code> attribute indicates that the function is always close
enough for the shorter calling sequence to be used. These attributes
override both the <samp>-mlongcall</samp> switch and
the <code>#pragma longcall</code> setting.
</p>
<p>See <a href="RS_002f6000-and-PowerPC-Options.html#RS_002f6000-and-PowerPC-Options">RS/6000 and PowerPC Options</a>, for more information on whether long
calls are necessary.
</p>
</dd>
<dt><code>target (<var>options</var>)</code></dt>
<dd><a name="index-target-function-attribute-3"></a>
<p>As discussed in <a href="Common-Function-Attributes.html#Common-Function-Attributes">Common Function Attributes</a>, this attribute
allows specification of target-specific compilation options.
</p>
<p>On the PowerPC, the following options are allowed:
</p>
<dl compact="compact">
<dt>&lsquo;<samp>altivec</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-altivec</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022altivec_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) AltiVec instructions. In
32-bit code, you cannot enable AltiVec instructions unless
<samp>-mabi=altivec</samp> is used on the command line.
</p>
</dd>
<dt>&lsquo;<samp>cmpb</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-cmpb</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022cmpb_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the compare bytes instruction
implemented on the POWER6 processor and other processors that support
the PowerPC V2.05 architecture.
</p>
</dd>
<dt>&lsquo;<samp>dlmzb</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-dlmzb</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022dlmzb_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the string-search &lsquo;<samp>dlmzb</samp>&rsquo;
instruction on the IBM 405, 440, 464 and 476 processors. This instruction is
generated by default when targeting those processors.
</p>
</dd>
<dt>&lsquo;<samp>fprnd</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-fprnd</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022fprnd_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the FP round to integer
instructions implemented on the POWER5+ processor and other processors
that support the PowerPC V2.03 architecture.
</p>
</dd>
<dt>&lsquo;<samp>hard-dfp</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-hard-dfp</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022hard_002ddfp_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the decimal floating-point
instructions implemented on some POWER processors.
</p>
</dd>
<dt>&lsquo;<samp>isel</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-isel</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022isel_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) ISEL instruction.
</p>
</dd>
<dt>&lsquo;<samp>mfcrf</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-mfcrf</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022mfcrf_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the move from condition
register field instruction implemented on the POWER4 processor and
other processors that support the PowerPC V2.01 architecture.
</p>
</dd>
<dt>&lsquo;<samp>mfpgpr</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-mfpgpr</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022mfpgpr_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the FP move to/from general
purpose register instructions implemented on the POWER6X processor and
other processors that support the extended PowerPC V2.05 architecture.
</p>
</dd>
<dt>&lsquo;<samp>mulhw</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-mulhw</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022mulhw_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the half-word multiply and
multiply-accumulate instructions on the IBM 405, 440, 464 and 476 processors.
These instructions are generated by default when targeting those
processors.
</p>
</dd>
<dt>&lsquo;<samp>multiple</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-multiple</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022multiple_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the load multiple word
instructions and the store multiple word instructions.
</p>
</dd>
<dt>&lsquo;<samp>update</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-update</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022update_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the load or store instructions
that update the base register to the address of the calculated memory
location.
</p>
</dd>
<dt>&lsquo;<samp>popcntb</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-popcntb</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022popcntb_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the popcount and double-precision
FP reciprocal estimate instruction implemented on the POWER5
processor and other processors that support the PowerPC V2.02
architecture.
</p>
</dd>
<dt>&lsquo;<samp>popcntd</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-popcntd</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022popcntd_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the popcount instruction
implemented on the POWER7 processor and other processors that support
the PowerPC V2.06 architecture.
</p>
</dd>
<dt>&lsquo;<samp>powerpc-gfxopt</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-powerpc-gfxopt</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022powerpc_002dgfxopt_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the optional PowerPC
architecture instructions in the Graphics group, including
floating-point select.
</p>
</dd>
<dt>&lsquo;<samp>powerpc-gpopt</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-powerpc-gpopt</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022powerpc_002dgpopt_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the optional PowerPC
architecture instructions in the General Purpose group, including
floating-point square root.
</p>
</dd>
<dt>&lsquo;<samp>recip-precision</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-recip-precision</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022recip_002dprecision_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Assume (do not assume) that the reciprocal estimate instructions
provide higher-precision estimates than is mandated by the PowerPC
ABI.
</p>
</dd>
<dt>&lsquo;<samp>string</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-string</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022string_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the load string instructions
and the store string word instructions to save multiple registers and
do small block moves.
</p>
</dd>
<dt>&lsquo;<samp>vsx</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-vsx</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022vsx_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) vector/scalar (VSX)
instructions, and also enable the use of built-in functions that allow
more direct access to the VSX instruction set. In 32-bit code, you
cannot enable VSX or AltiVec instructions unless
<samp>-mabi=altivec</samp> is used on the command line.
</p>
</dd>
<dt>&lsquo;<samp>friz</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-friz</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022friz_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate (do not generate) the <code>friz</code> instruction when the
<samp>-funsafe-math-optimizations</samp> option is used to optimize
rounding a floating-point value to 64-bit integer and back to floating
point. The <code>friz</code> instruction does not return the same value if
the floating-point number is too large to fit in an integer.
</p>
</dd>
<dt>&lsquo;<samp>avoid-indexed-addresses</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-avoid-indexed-addresses</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022avoid_002dindexed_002daddresses_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that tries to avoid (not avoid) the use of indexed load
or store instructions.
</p>
</dd>
<dt>&lsquo;<samp>paired</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-paired</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022paired_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that uses (does not use) the generation of PAIRED simd
instructions.
</p>
</dd>
<dt>&lsquo;<samp>longcall</samp>&rsquo;</dt>
<dt>&lsquo;<samp>no-longcall</samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022longcall_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Generate code that assumes (does not assume) that all calls are far
away so that a longer more expensive calling sequence is required.
</p>
</dd>
<dt>&lsquo;<samp>cpu=<var>CPU</var></samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022cpu_003dCPU_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Specify the architecture to generate code for when compiling the
function. If you select the <code>target(&quot;cpu=power7&quot;)</code> attribute when
generating 32-bit code, VSX and AltiVec instructions are not generated
unless you use the <samp>-mabi=altivec</samp> option on the command line.
</p>
</dd>
<dt>&lsquo;<samp>tune=<var>TUNE</var></samp>&rsquo;</dt>
<dd><a name="index-target_0028_0022tune_003dTUNE_0022_0029-function-attribute_002c-PowerPC"></a>
<p>Specify the architecture to tune for when compiling the function. If
you do not specify the <code>target(&quot;tune=<var>TUNE</var>&quot;)</code> attribute and
you do specify the <code>target(&quot;cpu=<var>CPU</var>&quot;)</code> attribute,
compilation tunes for the <var>CPU</var> architecture, and not the
default tuning specified on the command line.
</p></dd>
</dl>
<p>On the PowerPC, the inliner does not inline a
function that has different target options than the caller, unless the
callee has a subset of the target options of the caller.
</p></dd>
</dl>
<hr>
<div class="header">
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Next: <a href="RL78-Function-Attributes.html#RL78-Function-Attributes" accesskey="n" rel="next">RL78 Function Attributes</a>, Previous: <a href="Nvidia-PTX-Function-Attributes.html#Nvidia-PTX-Function-Attributes" accesskey="p" rel="prev">Nvidia PTX Function Attributes</a>, Up: <a href="Function-Attributes.html#Function-Attributes" accesskey="u" rel="up">Function Attributes</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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