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<h4 class="subsection">17.20.10 Assembler Commands for Alignment</h4>
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<p>This describes commands for alignment.
<div class="defun">
— Macro: <b>JUMP_ALIGN</b> (<var>label</var>)<var><a name="index-JUMP_005fALIGN-4737"></a></var><br>
<blockquote><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>This macro need not be defined if you don't want any special alignment
to be done at such a time. Most machine descriptions do not currently
define the macro.
<p>Unless it's necessary to inspect the <var>label</var> parameter, it is better
to set the variable <var>align_jumps</var> in the target's
<code>TARGET_OPTION_OVERRIDE</code>. Otherwise, you should try to honor the user's
selection in <var>align_jumps</var> in a <code>JUMP_ALIGN</code> implementation.
</p></blockquote></div>
<div class="defun">
— Target Hook: int <b>TARGET_ASM_JUMP_ALIGN_MAX_SKIP</b> (<var>rtx_insn *label</var>)<var><a name="index-TARGET_005fASM_005fJUMP_005fALIGN_005fMAX_005fSKIP-4738"></a></var><br>
<blockquote><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></blockquote></div>
<div class="defun">
— Macro: <b>LABEL_ALIGN_AFTER_BARRIER</b> (<var>label</var>)<var><a name="index-LABEL_005fALIGN_005fAFTER_005fBARRIER-4739"></a></var><br>
<blockquote><p>The alignment (log base 2) to put in front of <var>label</var>, which follows
a <code>BARRIER</code>.
<p>This macro need not be defined if you don't want any special alignment
to be done at such a time. Most machine descriptions do not currently
define the macro.
</p></blockquote></div>
<div class="defun">
— Target Hook: int <b>TARGET_ASM_LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP</b> (<var>rtx_insn *label</var>)<var><a name="index-TARGET_005fASM_005fLABEL_005fALIGN_005fAFTER_005fBARRIER_005fMAX_005fSKIP-4740"></a></var><br>
<blockquote><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></blockquote></div>
<div class="defun">
— Macro: <b>LOOP_ALIGN</b> (<var>label</var>)<var><a name="index-LOOP_005fALIGN-4741"></a></var><br>
<blockquote><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>This macro need not be defined if you don't want any special alignment
to be done at such a time. Most machine descriptions do not currently
define the macro.
<p>Unless it's necessary to inspect the <var>label</var> parameter, it is better
to set the variable <code>align_loops</code> in the target's
<code>TARGET_OPTION_OVERRIDE</code>. Otherwise, you should try to honor the user's
selection in <code>align_loops</code> in a <code>LOOP_ALIGN</code> implementation.
</p></blockquote></div>
<div class="defun">
— Target Hook: int <b>TARGET_ASM_LOOP_ALIGN_MAX_SKIP</b> (<var>rtx_insn *label</var>)<var><a name="index-TARGET_005fASM_005fLOOP_005fALIGN_005fMAX_005fSKIP-4742"></a></var><br>
<blockquote><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></blockquote></div>
<div class="defun">
— Macro: <b>LABEL_ALIGN</b> (<var>label</var>)<var><a name="index-LABEL_005fALIGN-4743"></a></var><br>
<blockquote><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>Unless it's necessary to inspect the <var>label</var> parameter, it is better
to set the variable <code>align_labels</code> in the target's
<code>TARGET_OPTION_OVERRIDE</code>. Otherwise, you should try to honor the user's
selection in <code>align_labels</code> in a <code>LABEL_ALIGN</code> implementation.
</p></blockquote></div>
<div class="defun">
— Target Hook: int <b>TARGET_ASM_LABEL_ALIGN_MAX_SKIP</b> (<var>rtx_insn *label</var>)<var><a name="index-TARGET_005fASM_005fLABEL_005fALIGN_005fMAX_005fSKIP-4744"></a></var><br>
<blockquote><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></blockquote></div>
<div class="defun">
— Macro: <b>ASM_OUTPUT_SKIP</b> (<var>stream, nbytes</var>)<var><a name="index-ASM_005fOUTPUT_005fSKIP-4745"></a></var><br>
<blockquote><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></blockquote></div>
<div class="defun">
— Macro: <b>ASM_NO_SKIP_IN_TEXT</b><var><a name="index-ASM_005fNO_005fSKIP_005fIN_005fTEXT-4746"></a></var><br>
<blockquote><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–op to skip bytes
produces no-op instructions rather than zeros when used in the text
section.
</p></blockquote></div>
<div class="defun">
— Macro: <b>ASM_OUTPUT_ALIGN</b> (<var>stream, power</var>)<var><a name="index-ASM_005fOUTPUT_005fALIGN-4747"></a></var><br>
<blockquote><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></blockquote></div>
<div class="defun">
— Macro: <b>ASM_OUTPUT_ALIGN_WITH_NOP</b> (<var>stream, power</var>)<var><a name="index-ASM_005fOUTPUT_005fALIGN_005fWITH_005fNOP-4748"></a></var><br>
<blockquote><p>Like <code>ASM_OUTPUT_ALIGN</code>, except that the “nop” instruction is used
for padding, if necessary.
</p></blockquote></div>
<div class="defun">
— Macro: <b>ASM_OUTPUT_MAX_SKIP_ALIGN</b> (<var>stream, power, max_skip</var>)<var><a name="index-ASM_005fOUTPUT_005fMAX_005fSKIP_005fALIGN-4749"></a></var><br>
<blockquote><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></blockquote></div>
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