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204 lines
9.8 KiB
HTML
204 lines
9.8 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2018 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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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Library Calls (GNU Compiler Collection (GCC) Internals)</title>
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<meta name="description" content="Library Calls (GNU Compiler Collection (GCC) Internals)">
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<meta name="keywords" content="Library Calls (GNU Compiler Collection (GCC) Internals)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Target-Macros.html#Target-Macros" rel="up" title="Target Macros">
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<link href="Addressing-Modes.html#Addressing-Modes" rel="next" title="Addressing Modes">
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<link href="Trampolines.html#Trampolines" rel="prev" title="Trampolines">
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<style type="text/css">
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Library-Calls"></a>
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<div class="header">
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<p>
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Next: <a href="Addressing-Modes.html#Addressing-Modes" accesskey="n" rel="next">Addressing Modes</a>, Previous: <a href="Trampolines.html#Trampolines" accesskey="p" rel="prev">Trampolines</a>, Up: <a href="Target-Macros.html#Target-Macros" accesskey="u" rel="up">Target Macros</a> [<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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</div>
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<hr>
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<a name="Implicit-Calls-to-Library-Routines"></a>
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<h3 class="section">18.12 Implicit Calls to Library Routines</h3>
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<a name="index-library-subroutine-names"></a>
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<a name="index-libgcc_002ea"></a>
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<p>Here is an explanation of implicit calls to library routines.
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</p>
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<dl>
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<dt><a name="index-DECLARE_005fLIBRARY_005fRENAMES"></a>Macro: <strong>DECLARE_LIBRARY_RENAMES</strong></dt>
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<dd><p>This macro, if defined, should expand to a piece of C code that will get
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expanded when compiling functions for libgcc.a. It can be used to
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provide alternate names for GCC’s internal library functions if there
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are ABI-mandated names that the compiler should provide.
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</p></dd></dl>
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<a name="index-set_005foptab_005flibfunc"></a>
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<a name="index-init_005fone_005flibfunc"></a>
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<dl>
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<dt><a name="index-TARGET_005fINIT_005fLIBFUNCS"></a>Target Hook: <em>void</em> <strong>TARGET_INIT_LIBFUNCS</strong> <em>(void)</em></dt>
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<dd><p>This hook should declare additional library routines or rename
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existing ones, using the functions <code>set_optab_libfunc</code> and
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<code>init_one_libfunc</code> defined in <samp>optabs.c</samp>.
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<code>init_optabs</code> calls this macro after initializing all the normal
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library routines.
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</p>
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<p>The default is to do nothing. Most ports don’t need to define this hook.
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</p></dd></dl>
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<dl>
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<dt><a name="index-TARGET_005fLIBFUNC_005fGNU_005fPREFIX"></a>Target Hook: <em>bool</em> <strong>TARGET_LIBFUNC_GNU_PREFIX</strong></dt>
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<dd><p>If false (the default), internal library routines start with two
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underscores. If set to true, these routines start with <code>__gnu_</code>
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instead. E.g., <code>__muldi3</code> changes to <code>__gnu_muldi3</code>. This
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currently only affects functions defined in <samp>libgcc2.c</samp>. If this
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is set to true, the <samp>tm.h</samp> file must also
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<code>#define LIBGCC2_GNU_PREFIX</code>.
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</p></dd></dl>
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<dl>
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<dt><a name="index-FLOAT_005fLIB_005fCOMPARE_005fRETURNS_005fBOOL"></a>Macro: <strong>FLOAT_LIB_COMPARE_RETURNS_BOOL</strong> <em>(<var>mode</var>, <var>comparison</var>)</em></dt>
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<dd><p>This macro should return <code>true</code> if the library routine that
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implements the floating point comparison operator <var>comparison</var> in
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mode <var>mode</var> will return a boolean, and <var>false</var> if it will
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return a tristate.
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</p>
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<p>GCC’s own floating point libraries return tristates from the
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comparison operators, so the default returns false always. Most ports
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don’t need to define this macro.
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</p></dd></dl>
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<dl>
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<dt><a name="index-TARGET_005fLIB_005fINT_005fCMP_005fBIASED"></a>Macro: <strong>TARGET_LIB_INT_CMP_BIASED</strong></dt>
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<dd><p>This macro should evaluate to <code>true</code> if the integer comparison
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functions (like <code>__cmpdi2</code>) return 0 to indicate that the first
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operand is smaller than the second, 1 to indicate that they are equal,
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and 2 to indicate that the first operand is greater than the second.
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If this macro evaluates to <code>false</code> the comparison functions return
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-1, 0, and 1 instead of 0, 1, and 2. If the target uses the routines
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in <samp>libgcc.a</samp>, you do not need to define this macro.
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</p></dd></dl>
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<dl>
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<dt><a name="index-TARGET_005fHAS_005fNO_005fHW_005fDIVIDE"></a>Macro: <strong>TARGET_HAS_NO_HW_DIVIDE</strong></dt>
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<dd><p>This macro should be defined if the target has no hardware divide
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instructions. If this macro is defined, GCC will use an algorithm which
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make use of simple logical and arithmetic operations for 64-bit
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division. If the macro is not defined, GCC will use an algorithm which
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make use of a 64-bit by 32-bit divide primitive.
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</p></dd></dl>
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<a name="index-EDOM_002c-implicit-usage"></a>
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<a name="index-matherr"></a>
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<dl>
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<dt><a name="index-TARGET_005fEDOM"></a>Macro: <strong>TARGET_EDOM</strong></dt>
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<dd><p>The value of <code>EDOM</code> on the target machine, as a C integer constant
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expression. If you don’t define this macro, GCC does not attempt to
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deposit the value of <code>EDOM</code> into <code>errno</code> directly. Look in
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<samp>/usr/include/errno.h</samp> to find the value of <code>EDOM</code> on your
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system.
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</p>
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<p>If you do not define <code>TARGET_EDOM</code>, then compiled code reports
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domain errors by calling the library function and letting it report the
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error. If mathematical functions on your system use <code>matherr</code> when
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there is an error, then you should leave <code>TARGET_EDOM</code> undefined so
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that <code>matherr</code> is used normally.
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</p></dd></dl>
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<a name="index-errno_002c-implicit-usage"></a>
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<dl>
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<dt><a name="index-GEN_005fERRNO_005fRTX"></a>Macro: <strong>GEN_ERRNO_RTX</strong></dt>
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<dd><p>Define this macro as a C expression to create an rtl expression that
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refers to the global “variable” <code>errno</code>. (On certain systems,
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<code>errno</code> may not actually be a variable.) If you don’t define this
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macro, a reasonable default is used.
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</p></dd></dl>
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<dl>
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<dt><a name="index-TARGET_005fLIBC_005fHAS_005fFUNCTION"></a>Target Hook: <em>bool</em> <strong>TARGET_LIBC_HAS_FUNCTION</strong> <em>(enum function_class <var>fn_class</var>)</em></dt>
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<dd><p>This hook determines whether a function from a class of functions
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<var>fn_class</var> is present at the runtime.
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</p></dd></dl>
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<dl>
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<dt><a name="index-NEXT_005fOBJC_005fRUNTIME"></a>Macro: <strong>NEXT_OBJC_RUNTIME</strong></dt>
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<dd><p>Set this macro to 1 to use the "NeXT" Objective-C message sending conventions
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by default. This calling convention involves passing the object, the selector
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and the method arguments all at once to the method-lookup library function.
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This is the usual setting when targeting Darwin/Mac OS X systems, which have
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the NeXT runtime installed.
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</p>
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<p>If the macro is set to 0, the "GNU" Objective-C message sending convention
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will be used by default. This convention passes just the object and the
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selector to the method-lookup function, which returns a pointer to the method.
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</p>
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<p>In either case, it remains possible to select code-generation for the alternate
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scheme, by means of compiler command line switches.
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</p></dd></dl>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Addressing-Modes.html#Addressing-Modes" accesskey="n" rel="next">Addressing Modes</a>, Previous: <a href="Trampolines.html#Trampolines" accesskey="p" rel="prev">Trampolines</a>, Up: <a href="Target-Macros.html#Target-Macros" accesskey="u" rel="up">Target Macros</a> [<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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</div>
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</body>
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</html>
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