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<a name="Alignment-Output"></a>
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<hr>
<a name="Assembler-Commands-for-Alignment"></a>
<h4 class="subsection">17.20.10 Assembler Commands for Alignment</h4>

<p>This describes commands for alignment.
</p>
<dl>
<dt><a name="index-JUMP_005fALIGN"></a>Macro: <strong>JUMP_ALIGN</strong> <em>(<var>label</var>)</em></dt>
<dd><p>The alignment (log base 2) to put in front of <var>label</var>, which is
a common destination of jumps and has no fallthru incoming edge.
</p>
<p>This macro need not be defined if you don&rsquo;t want any special alignment
to be done at such a time.  Most machine descriptions do not currently
define the macro.
</p>
<p>Unless it&rsquo;s necessary to inspect the <var>label</var> parameter, it is better
to set the variable <var>align_jumps</var> in the target&rsquo;s
<code>TARGET_OPTION_OVERRIDE</code>.  Otherwise, you should try to honor the user&rsquo;s
selection in <var>align_jumps</var> in a <code>JUMP_ALIGN</code> implementation.
</p></dd></dl>

<dl>
<dt><a name="index-TARGET_005fASM_005fJUMP_005fALIGN_005fMAX_005fSKIP"></a>Target Hook: <em>int</em> <strong>TARGET_ASM_JUMP_ALIGN_MAX_SKIP</strong> <em>(rtx_insn *<var>label</var>)</em></dt>
<dd><p>The maximum number of bytes to skip before <var>label</var> when applying
<code>JUMP_ALIGN</code>.  This works only if
<code>ASM_OUTPUT_MAX_SKIP_ALIGN</code> is defined.
</p></dd></dl>

<dl>
<dt><a name="index-LABEL_005fALIGN_005fAFTER_005fBARRIER"></a>Macro: <strong>LABEL_ALIGN_AFTER_BARRIER</strong> <em>(<var>label</var>)</em></dt>
<dd><p>The alignment (log base 2) to put in front of <var>label</var>, which follows
a <code>BARRIER</code>.
</p>
<p>This macro need not be defined if you don&rsquo;t want any special alignment
to be done at such a time.  Most machine descriptions do not currently
define the macro.
</p></dd></dl>

<dl>
<dt><a name="index-TARGET_005fASM_005fLABEL_005fALIGN_005fAFTER_005fBARRIER_005fMAX_005fSKIP"></a>Target Hook: <em>int</em> <strong>TARGET_ASM_LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP</strong> <em>(rtx_insn *<var>label</var>)</em></dt>
<dd><p>The maximum number of bytes to skip before <var>label</var> when applying
<code>LABEL_ALIGN_AFTER_BARRIER</code>.  This works only if
<code>ASM_OUTPUT_MAX_SKIP_ALIGN</code> is defined.
</p></dd></dl>

<dl>
<dt><a name="index-LOOP_005fALIGN"></a>Macro: <strong>LOOP_ALIGN</strong> <em>(<var>label</var>)</em></dt>
<dd><p>The alignment (log base 2) to put in front of <var>label</var> that heads
a frequently executed basic block (usually the header of a loop).
</p>
<p>This macro need not be defined if you don&rsquo;t want any special alignment
to be done at such a time.  Most machine descriptions do not currently
define the macro.
</p>
<p>Unless it&rsquo;s necessary to inspect the <var>label</var> parameter, it is better
to set the variable <code>align_loops</code> in the target&rsquo;s
<code>TARGET_OPTION_OVERRIDE</code>.  Otherwise, you should try to honor the user&rsquo;s
selection in <code>align_loops</code> in a <code>LOOP_ALIGN</code> implementation.
</p></dd></dl>

<dl>
<dt><a name="index-TARGET_005fASM_005fLOOP_005fALIGN_005fMAX_005fSKIP"></a>Target Hook: <em>int</em> <strong>TARGET_ASM_LOOP_ALIGN_MAX_SKIP</strong> <em>(rtx_insn *<var>label</var>)</em></dt>
<dd><p>The maximum number of bytes to skip when applying <code>LOOP_ALIGN</code> to
<var>label</var>.  This works only if <code>ASM_OUTPUT_MAX_SKIP_ALIGN</code> is
defined.
</p></dd></dl>

<dl>
<dt><a name="index-LABEL_005fALIGN"></a>Macro: <strong>LABEL_ALIGN</strong> <em>(<var>label</var>)</em></dt>
<dd><p>The alignment (log base 2) to put in front of <var>label</var>.
If <code>LABEL_ALIGN_AFTER_BARRIER</code> / <code>LOOP_ALIGN</code> specify a different alignment,
the maximum of the specified values is used.
</p>
<p>Unless it&rsquo;s necessary to inspect the <var>label</var> parameter, it is better
to set the variable <code>align_labels</code> in the target&rsquo;s
<code>TARGET_OPTION_OVERRIDE</code>.  Otherwise, you should try to honor the user&rsquo;s
selection in <code>align_labels</code> in a <code>LABEL_ALIGN</code> implementation.
</p></dd></dl>

<dl>
<dt><a name="index-TARGET_005fASM_005fLABEL_005fALIGN_005fMAX_005fSKIP"></a>Target Hook: <em>int</em> <strong>TARGET_ASM_LABEL_ALIGN_MAX_SKIP</strong> <em>(rtx_insn *<var>label</var>)</em></dt>
<dd><p>The maximum number of bytes to skip when applying <code>LABEL_ALIGN</code>
to <var>label</var>.  This works only if <code>ASM_OUTPUT_MAX_SKIP_ALIGN</code>
is defined.
</p></dd></dl>

<dl>
<dt><a name="index-ASM_005fOUTPUT_005fSKIP"></a>Macro: <strong>ASM_OUTPUT_SKIP</strong> <em>(<var>stream</var>, <var>nbytes</var>)</em></dt>
<dd><p>A C statement to output to the stdio stream <var>stream</var> an assembler
instruction to advance the location counter by <var>nbytes</var> bytes.
Those bytes should be zero when loaded.  <var>nbytes</var> will be a C
expression of type <code>unsigned HOST_WIDE_INT</code>.
</p></dd></dl>

<dl>
<dt><a name="index-ASM_005fNO_005fSKIP_005fIN_005fTEXT"></a>Macro: <strong>ASM_NO_SKIP_IN_TEXT</strong></dt>
<dd><p>Define this macro if <code>ASM_OUTPUT_SKIP</code> should not be used in the
text section because it fails to put zeros in the bytes that are skipped.
This is true on many Unix systems, where the pseudo&ndash;op to skip bytes
produces no-op instructions rather than zeros when used in the text
section.
</p></dd></dl>

<dl>
<dt><a name="index-ASM_005fOUTPUT_005fALIGN"></a>Macro: <strong>ASM_OUTPUT_ALIGN</strong> <em>(<var>stream</var>, <var>power</var>)</em></dt>
<dd><p>A C statement to output to the stdio stream <var>stream</var> an assembler
command to advance the location counter to a multiple of 2 to the
<var>power</var> bytes.  <var>power</var> will be a C expression of type <code>int</code>.
</p></dd></dl>

<dl>
<dt><a name="index-ASM_005fOUTPUT_005fALIGN_005fWITH_005fNOP"></a>Macro: <strong>ASM_OUTPUT_ALIGN_WITH_NOP</strong> <em>(<var>stream</var>, <var>power</var>)</em></dt>
<dd><p>Like <code>ASM_OUTPUT_ALIGN</code>, except that the &ldquo;nop&rdquo; instruction is used
for padding, if necessary.
</p></dd></dl>

<dl>
<dt><a name="index-ASM_005fOUTPUT_005fMAX_005fSKIP_005fALIGN"></a>Macro: <strong>ASM_OUTPUT_MAX_SKIP_ALIGN</strong> <em>(<var>stream</var>, <var>power</var>, <var>max_skip</var>)</em></dt>
<dd><p>A C statement to output to the stdio stream <var>stream</var> an assembler
command to advance the location counter to a multiple of 2 to the
<var>power</var> bytes, but only if <var>max_skip</var> or fewer bytes are needed to
satisfy the alignment request.  <var>power</var> and <var>max_skip</var> will be
a C expression of type <code>int</code>.
</p></dd></dl>

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