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| <a name="Library-Calls"></a> |
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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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| <hr> |
| <a name="Implicit-Calls-to-Library-Routines"></a> |
| <h3 class="section">17.13 Implicit Calls to Library Routines</h3> |
| <a name="index-library-subroutine-names"></a> |
| <a name="index-libgcc_002ea"></a> |
| |
| <p>Here is an explanation of implicit calls to library routines. |
| </p> |
| <dl> |
| <dt><a name="index-DECLARE_005fLIBRARY_005fRENAMES"></a>Macro: <strong>DECLARE_LIBRARY_RENAMES</strong></dt> |
| <dd><p>This macro, if defined, should expand to a piece of C code that will get |
| expanded when compiling functions for libgcc.a. It can be used to |
| provide alternate names for GCC’s internal library functions if there |
| are ABI-mandated names that the compiler should provide. |
| </p></dd></dl> |
| |
| <a name="index-set_005foptab_005flibfunc"></a> |
| <a name="index-init_005fone_005flibfunc"></a> |
| <dl> |
| <dt><a name="index-TARGET_005fINIT_005fLIBFUNCS"></a>Target Hook: <em>void</em> <strong>TARGET_INIT_LIBFUNCS</strong> <em>(void)</em></dt> |
| <dd><p>This hook should declare additional library routines or rename |
| existing ones, using the functions <code>set_optab_libfunc</code> and |
| <code>init_one_libfunc</code> defined in <samp>optabs.c</samp>. |
| <code>init_optabs</code> calls this macro after initializing all the normal |
| library routines. |
| </p> |
| <p>The default is to do nothing. Most ports don’t need to define this hook. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fLIBFUNC_005fGNU_005fPREFIX"></a>Target Hook: <em>bool</em> <strong>TARGET_LIBFUNC_GNU_PREFIX</strong></dt> |
| <dd><p>If false (the default), internal library routines start with two |
| underscores. If set to true, these routines start with <code>__gnu_</code> |
| instead. E.g., <code>__muldi3</code> changes to <code>__gnu_muldi3</code>. This |
| currently only affects functions defined in <samp>libgcc2.c</samp>. If this |
| is set to true, the <samp>tm.h</samp> file must also |
| <code>#define LIBGCC2_GNU_PREFIX</code>. |
| </p></dd></dl> |
| |
| <dl> |
| <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> |
| <dd><p>This macro should return <code>true</code> if the library routine that |
| implements the floating point comparison operator <var>comparison</var> in |
| mode <var>mode</var> will return a boolean, and <var>false</var> if it will |
| return a tristate. |
| </p> |
| <p>GCC’s own floating point libraries return tristates from the |
| comparison operators, so the default returns false always. Most ports |
| don’t need to define this macro. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fLIB_005fINT_005fCMP_005fBIASED"></a>Macro: <strong>TARGET_LIB_INT_CMP_BIASED</strong></dt> |
| <dd><p>This macro should evaluate to <code>true</code> if the integer comparison |
| functions (like <code>__cmpdi2</code>) return 0 to indicate that the first |
| operand is smaller than the second, 1 to indicate that they are equal, |
| and 2 to indicate that the first operand is greater than the second. |
| If this macro evaluates to <code>false</code> the comparison functions return |
| -1, 0, and 1 instead of 0, 1, and 2. If the target uses the routines |
| in <samp>libgcc.a</samp>, you do not need to define this macro. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fHAS_005fNO_005fHW_005fDIVIDE"></a>Macro: <strong>TARGET_HAS_NO_HW_DIVIDE</strong></dt> |
| <dd><p>This macro should be defined if the target has no hardware divide |
| instructions. If this macro is defined, GCC will use an algorithm which |
| make use of simple logical and arithmetic operations for 64-bit |
| division. If the macro is not defined, GCC will use an algorithm which |
| make use of a 64-bit by 32-bit divide primitive. |
| </p></dd></dl> |
| |
| <a name="index-EDOM_002c-implicit-usage"></a> |
| <a name="index-matherr"></a> |
| <dl> |
| <dt><a name="index-TARGET_005fEDOM"></a>Macro: <strong>TARGET_EDOM</strong></dt> |
| <dd><p>The value of <code>EDOM</code> on the target machine, as a C integer constant |
| expression. If you don’t define this macro, GCC does not attempt to |
| deposit the value of <code>EDOM</code> into <code>errno</code> directly. Look in |
| <samp>/usr/include/errno.h</samp> to find the value of <code>EDOM</code> on your |
| system. |
| </p> |
| <p>If you do not define <code>TARGET_EDOM</code>, then compiled code reports |
| domain errors by calling the library function and letting it report the |
| error. If mathematical functions on your system use <code>matherr</code> when |
| there is an error, then you should leave <code>TARGET_EDOM</code> undefined so |
| that <code>matherr</code> is used normally. |
| </p></dd></dl> |
| |
| <a name="index-errno_002c-implicit-usage"></a> |
| <dl> |
| <dt><a name="index-GEN_005fERRNO_005fRTX"></a>Macro: <strong>GEN_ERRNO_RTX</strong></dt> |
| <dd><p>Define this macro as a C expression to create an rtl expression that |
| refers to the global “variable” <code>errno</code>. (On certain systems, |
| <code>errno</code> may not actually be a variable.) If you don’t define this |
| macro, a reasonable default is used. |
| </p></dd></dl> |
| |
| <dl> |
| <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> |
| <dd><p>This hook determines whether a function from a class of functions |
| <var>fn_class</var> is present at the runtime. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-NEXT_005fOBJC_005fRUNTIME"></a>Macro: <strong>NEXT_OBJC_RUNTIME</strong></dt> |
| <dd><p>Set this macro to 1 to use the "NeXT" Objective-C message sending conventions |
| by default. This calling convention involves passing the object, the selector |
| and the method arguments all at once to the method-lookup library function. |
| This is the usual setting when targeting Darwin/Mac OS X systems, which have |
| the NeXT runtime installed. |
| </p> |
| <p>If the macro is set to 0, the "GNU" Objective-C message sending convention |
| will be used by default. This convention passes just the object and the |
| selector to the method-lookup function, which returns a pointer to the method. |
| </p> |
| <p>In either case, it remains possible to select code-generation for the alternate |
| scheme, by means of compiler command line switches. |
| </p></dd></dl> |
| |
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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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