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175 lines
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175 lines
8.9 KiB
HTML
4 years ago
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<html lang="en">
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<head>
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<title>Library Calls - 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="Target-Macros.html#Target-Macros" title="Target Macros">
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<link rel="prev" href="Trampolines.html#Trampolines" title="Trampolines">
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<link rel="next" href="Addressing-Modes.html#Addressing-Modes" title="Addressing Modes">
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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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(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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funds for GNU development.-->
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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="Library-Calls"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Addressing-Modes.html#Addressing-Modes">Addressing Modes</a>,
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Previous: <a rel="previous" accesskey="p" href="Trampolines.html#Trampolines">Trampolines</a>,
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Up: <a rel="up" accesskey="u" href="Target-Macros.html#Target-Macros">Target Macros</a>
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<hr>
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</div>
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<h3 class="section">17.12 Implicit Calls to Library Routines</h3>
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<p><a name="index-library-subroutine-names-4353"></a><a name="index-g_t_0040file_007blibgcc_002ea_007d-4354"></a>
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<!-- prevent bad page break with this line -->
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Here is an explanation of implicit calls to library routines.
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<div class="defun">
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— Macro: <b>DECLARE_LIBRARY_RENAMES</b><var><a name="index-DECLARE_005fLIBRARY_005fRENAMES-4355"></a></var><br>
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<blockquote><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></blockquote></div>
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<p><a name="index-set_005foptab_005flibfunc-4356"></a><a name="index-init_005fone_005flibfunc-4357"></a>
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<div class="defun">
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— Target Hook: void <b>TARGET_INIT_LIBFUNCS</b> (<var>void</var>)<var><a name="index-TARGET_005fINIT_005fLIBFUNCS-4358"></a></var><br>
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<blockquote><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><span class="file">optabs.c</span></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>The default is to do nothing. Most ports don't need to define this hook.
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</p></blockquote></div>
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<div class="defun">
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— Target Hook: bool <b>TARGET_LIBFUNC_GNU_PREFIX</b><var><a name="index-TARGET_005fLIBFUNC_005fGNU_005fPREFIX-4359"></a></var><br>
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<blockquote><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><span class="file">libgcc2.c</span></samp>. If this
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is set to true, the <samp><span class="file">tm.h</span></samp> file must also
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<code>#define LIBGCC2_GNU_PREFIX</code>.
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</p></blockquote></div>
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<div class="defun">
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— Macro: <b>FLOAT_LIB_COMPARE_RETURNS_BOOL</b> (<var>mode, comparison</var>)<var><a name="index-FLOAT_005fLIB_005fCOMPARE_005fRETURNS_005fBOOL-4360"></a></var><br>
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<blockquote><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>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></blockquote></div>
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<div class="defun">
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— Macro: <b>TARGET_LIB_INT_CMP_BIASED</b><var><a name="index-TARGET_005fLIB_005fINT_005fCMP_005fBIASED-4361"></a></var><br>
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<blockquote><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><span class="file">libgcc.a</span></samp>, you do not need to define this macro.
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</p></blockquote></div>
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<div class="defun">
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— Macro: <b>TARGET_HAS_NO_HW_DIVIDE</b><var><a name="index-TARGET_005fHAS_005fNO_005fHW_005fDIVIDE-4362"></a></var><br>
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<blockquote><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></blockquote></div>
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<p><a name="index-g_t_0040code_007bEDOM_007d_002c-implicit-usage-4363"></a><a name="index-matherr-4364"></a>
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<div class="defun">
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— Macro: <b>TARGET_EDOM</b><var><a name="index-TARGET_005fEDOM-4365"></a></var><br>
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<blockquote><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><span class="file">/usr/include/errno.h</span></samp> to find the value of <code>EDOM</code> on your
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system.
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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></blockquote></div>
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<p><a name="index-g_t_0040code_007berrno_007d_002c-implicit-usage-4366"></a>
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<div class="defun">
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— Macro: <b>GEN_ERRNO_RTX</b><var><a name="index-GEN_005fERRNO_005fRTX-4367"></a></var><br>
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<blockquote><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></blockquote></div>
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<div class="defun">
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— Target Hook: bool <b>TARGET_LIBC_HAS_FUNCTION</b> (<var>enum function_class fn_class</var>)<var><a name="index-TARGET_005fLIBC_005fHAS_005fFUNCTION-4368"></a></var><br>
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<blockquote><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></blockquote></div>
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<div class="defun">
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— Macro: <b>NEXT_OBJC_RUNTIME</b><var><a name="index-NEXT_005fOBJC_005fRUNTIME-4369"></a></var><br>
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<blockquote><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>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>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></blockquote></div>
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</body></html>
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