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165 lines
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HTML
165 lines
8.3 KiB
HTML
4 years ago
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<html lang="en">
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<head>
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<title>Dispatch Tables - GNU Compiler Collection (GCC) Internals</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="GNU Compiler Collection (GCC) Internals">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Assembler-Format.html#Assembler-Format" title="Assembler Format">
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<link rel="prev" href="Instruction-Output.html#Instruction-Output" title="Instruction Output">
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<link rel="next" href="Exception-Region-Output.html#Exception-Region-Output" title="Exception Region Output">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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Copyright (C) 1988-2015 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being ``Funding Free Software'', the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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``GNU Free Documentation License''.
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development.-->
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<style type="text/css"><!--
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pre.display { font-family:inherit }
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--></style>
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</head>
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<body>
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<div class="node">
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<a name="Dispatch-Tables"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Exception-Region-Output.html#Exception-Region-Output">Exception Region Output</a>,
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Previous: <a rel="previous" accesskey="p" href="Instruction-Output.html#Instruction-Output">Instruction Output</a>,
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Up: <a rel="up" accesskey="u" href="Assembler-Format.html#Assembler-Format">Assembler Format</a>
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<hr>
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</div>
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<h4 class="subsection">17.20.8 Output of Dispatch Tables</h4>
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<!-- prevent bad page break with this line -->
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<p>This concerns dispatch tables.
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<p><a name="index-dispatch-table-4711"></a>
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<div class="defun">
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— Macro: <b>ASM_OUTPUT_ADDR_DIFF_ELT</b> (<var>stream, body, value, rel</var>)<var><a name="index-ASM_005fOUTPUT_005fADDR_005fDIFF_005fELT-4712"></a></var><br>
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<blockquote><p>A C statement to output to the stdio stream <var>stream</var> an assembler
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pseudo-instruction to generate a difference between two labels.
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<var>value</var> and <var>rel</var> are the numbers of two internal labels. The
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definitions of these labels are output using
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<code>(*targetm.asm_out.internal_label)</code>, and they must be printed in the same
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way here. For example,
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<pre class="smallexample"> fprintf (<var>stream</var>, "\t.word L%d-L%d\n",
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<var>value</var>, <var>rel</var>)
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</pre>
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<p>You must provide this macro on machines where the addresses in a
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dispatch table are relative to the table's own address. If defined, GCC
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will also use this macro on all machines when producing PIC.
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<var>body</var> is the body of the <code>ADDR_DIFF_VEC</code>; it is provided so that the
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mode and flags can be read.
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</p></blockquote></div>
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<div class="defun">
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— Macro: <b>ASM_OUTPUT_ADDR_VEC_ELT</b> (<var>stream, value</var>)<var><a name="index-ASM_005fOUTPUT_005fADDR_005fVEC_005fELT-4713"></a></var><br>
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<blockquote><p>This macro should be provided on machines where the addresses
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in a dispatch table are absolute.
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<p>The definition should be a C statement to output to the stdio stream
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<var>stream</var> an assembler pseudo-instruction to generate a reference to
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a label. <var>value</var> is the number of an internal label whose
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definition is output using <code>(*targetm.asm_out.internal_label)</code>.
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For example,
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<pre class="smallexample"> fprintf (<var>stream</var>, "\t.word L%d\n", <var>value</var>)
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</pre>
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</blockquote></div>
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<div class="defun">
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— Macro: <b>ASM_OUTPUT_CASE_LABEL</b> (<var>stream, prefix, num, table</var>)<var><a name="index-ASM_005fOUTPUT_005fCASE_005fLABEL-4714"></a></var><br>
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<blockquote><p>Define this if the label before a jump-table needs to be output
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specially. The first three arguments are the same as for
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<code>(*targetm.asm_out.internal_label)</code>; the fourth argument is the
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jump-table which follows (a <code>jump_table_data</code> containing an
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<code>addr_vec</code> or <code>addr_diff_vec</code>).
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<p>This feature is used on system V to output a <code>swbeg</code> statement
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for the table.
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<p>If this macro is not defined, these labels are output with
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<code>(*targetm.asm_out.internal_label)</code>.
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</p></blockquote></div>
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<div class="defun">
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— Macro: <b>ASM_OUTPUT_CASE_END</b> (<var>stream, num, table</var>)<var><a name="index-ASM_005fOUTPUT_005fCASE_005fEND-4715"></a></var><br>
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<blockquote><p>Define this if something special must be output at the end of a
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jump-table. The definition should be a C statement to be executed
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after the assembler code for the table is written. It should write
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the appropriate code to stdio stream <var>stream</var>. The argument
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<var>table</var> is the jump-table insn, and <var>num</var> is the label-number
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of the preceding label.
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<p>If this macro is not defined, nothing special is output at the end of
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the jump-table.
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</p></blockquote></div>
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<div class="defun">
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— Target Hook: void <b>TARGET_ASM_EMIT_UNWIND_LABEL</b> (<var>FILE *stream, tree decl, int for_eh, int empty</var>)<var><a name="index-TARGET_005fASM_005fEMIT_005fUNWIND_005fLABEL-4716"></a></var><br>
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<blockquote><p>This target hook emits a label at the beginning of each FDE. It
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should be defined on targets where FDEs need special labels, and it
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should write the appropriate label, for the FDE associated with the
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function declaration <var>decl</var>, to the stdio stream <var>stream</var>.
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The third argument, <var>for_eh</var>, is a boolean: true if this is for an
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exception table. The fourth argument, <var>empty</var>, is a boolean:
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true if this is a placeholder label for an omitted FDE.
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<p>The default is that FDEs are not given nonlocal labels.
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</p></blockquote></div>
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<div class="defun">
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— Target Hook: void <b>TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL</b> (<var>FILE *stream</var>)<var><a name="index-TARGET_005fASM_005fEMIT_005fEXCEPT_005fTABLE_005fLABEL-4717"></a></var><br>
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<blockquote><p>This target hook emits a label at the beginning of the exception table.
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It should be defined on targets where it is desirable for the table
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to be broken up according to function.
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<p>The default is that no label is emitted.
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</p></blockquote></div>
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<div class="defun">
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— Target Hook: void <b>TARGET_ASM_EMIT_EXCEPT_PERSONALITY</b> (<var>rtx personality</var>)<var><a name="index-TARGET_005fASM_005fEMIT_005fEXCEPT_005fPERSONALITY-4718"></a></var><br>
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<blockquote><p>If the target implements <code>TARGET_ASM_UNWIND_EMIT</code>, this hook may be used to emit a directive to install a personality hook into the unwind info. This hook should not be used if dwarf2 unwind info is used.
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</p></blockquote></div>
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<div class="defun">
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— Target Hook: void <b>TARGET_ASM_UNWIND_EMIT</b> (<var>FILE *stream, rtx_insn *insn</var>)<var><a name="index-TARGET_005fASM_005fUNWIND_005fEMIT-4719"></a></var><br>
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<blockquote><p>This target hook emits assembly directives required to unwind the
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given instruction. This is only used when <code>TARGET_EXCEPT_UNWIND_INFO</code>
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returns <code>UI_TARGET</code>.
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</p></blockquote></div>
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<div class="defun">
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— Target Hook: bool <b>TARGET_ASM_UNWIND_EMIT_BEFORE_INSN</b><var><a name="index-TARGET_005fASM_005fUNWIND_005fEMIT_005fBEFORE_005fINSN-4720"></a></var><br>
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<blockquote><p>True if the <code>TARGET_ASM_UNWIND_EMIT</code> hook should be called before the assembly for <var>insn</var> has been emitted, false if the hook should be called afterward.
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</p></blockquote></div>
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</body></html>
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