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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gccint/Run_002dtime-Target.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
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diff --git a/share/doc/gccint/Run_002dtime-Target.html b/share/doc/gccint/Run_002dtime-Target.html new file mode 100644 index 0000000..434ce9e --- /dev/null +++ b/share/doc/gccint/Run_002dtime-Target.html @@ -0,0 +1,321 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>GNU Compiler Collection (GCC) Internals: Run-time Target</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Run-time Target"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Run-time Target"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Target-Macros.html#Target-Macros" rel="up" title="Target Macros"> +<link href="Per_002dFunction-Data.html#Per_002dFunction-Data" rel="next" title="Per-Function Data"> +<link href="Driver.html#Driver" rel="previous" title="Driver"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Run_002dtime-Target"></a> +<div class="header"> +<p> +Next: <a href="Per_002dFunction-Data.html#Per_002dFunction-Data" accesskey="n" rel="next">Per-Function Data</a>, Previous: <a href="Driver.html#Driver" accesskey="p" rel="previous">Driver</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> +</div> +<hr> +<a name="Run_002dtime-Target-Specification"></a> +<h3 class="section">18.3 Run-time Target Specification</h3> +<a name="index-run_002dtime-target-specification"></a> +<a name="index-predefined-macros"></a> +<a name="index-target-specifications"></a> + +<p>Here are run-time target specifications. +</p> +<dl> +<dt><a name="index-TARGET_005fCPU_005fCPP_005fBUILTINS"></a>Macro: <strong>TARGET_CPU_CPP_BUILTINS</strong> <em>()</em></dt> +<dd><p>This function-like macro expands to a block of code that defines +built-in preprocessor macros and assertions for the target CPU, using +the functions <code>builtin_define</code>, <code>builtin_define_std</code> and +<code>builtin_assert</code>. When the front end +calls this macro it provides a trailing semicolon, and since it has +finished command line option processing your code can use those +results freely. +</p> +<p><code>builtin_assert</code> takes a string in the form you pass to the +command-line option <samp>-A</samp>, such as <code>cpu=mips</code>, and creates +the assertion. <code>builtin_define</code> takes a string in the form +accepted by option <samp>-D</samp> and unconditionally defines the macro. +</p> +<p><code>builtin_define_std</code> takes a string representing the name of an +object-like macro. If it doesn’t lie in the user’s namespace, +<code>builtin_define_std</code> defines it unconditionally. Otherwise, it +defines a version with two leading underscores, and another version +with two leading and trailing underscores, and defines the original +only if an ISO standard was not requested on the command line. For +example, passing <code>unix</code> defines <code>__unix</code>, <code>__unix__</code> +and possibly <code>unix</code>; passing <code>_mips</code> defines <code>__mips</code>, +<code>__mips__</code> and possibly <code>_mips</code>, and passing <code>_ABI64</code> +defines only <code>_ABI64</code>. +</p> +<p>You can also test for the C dialect being compiled. The variable +<code>c_language</code> is set to one of <code>clk_c</code>, <code>clk_cplusplus</code> +or <code>clk_objective_c</code>. Note that if we are preprocessing +assembler, this variable will be <code>clk_c</code> but the function-like +macro <code>preprocessing_asm_p()</code> will return true, so you might want +to check for that first. If you need to check for strict ANSI, the +variable <code>flag_iso</code> can be used. The function-like macro +<code>preprocessing_trad_p()</code> can be used to check for traditional +preprocessing. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOS_005fCPP_005fBUILTINS"></a>Macro: <strong>TARGET_OS_CPP_BUILTINS</strong> <em>()</em></dt> +<dd><p>Similarly to <code>TARGET_CPU_CPP_BUILTINS</code> but this macro is optional +and is used for the target operating system instead. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOBJFMT_005fCPP_005fBUILTINS"></a>Macro: <strong>TARGET_OBJFMT_CPP_BUILTINS</strong> <em>()</em></dt> +<dd><p>Similarly to <code>TARGET_CPU_CPP_BUILTINS</code> but this macro is optional +and is used for the target object format. <samp>elfos.h</samp> uses this +macro to define <code>__ELF__</code>, so you probably do not need to define +it yourself. +</p></dd></dl> + +<dl> +<dt><a name="index-target_005fflags"></a>Variable: <em>extern int</em> <strong>target_flags</strong></dt> +<dd><p>This variable is declared in <samp>options.h</samp>, which is included before +any target-specific headers. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fDEFAULT_005fTARGET_005fFLAGS"></a>Common Target Hook: <em>int</em> <strong>TARGET_DEFAULT_TARGET_FLAGS</strong></dt> +<dd><p>This variable specifies the initial value of <code>target_flags</code>. +Its default setting is 0. +</p></dd></dl> + +<a name="index-optional-hardware-or-system-features"></a> +<a name="index-features_002c-optional_002c-in-system-conventions"></a> + +<dl> +<dt><a name="index-TARGET_005fHANDLE_005fOPTION"></a>Common Target Hook: <em>bool</em> <strong>TARGET_HANDLE_OPTION</strong> <em>(struct gcc_options *<var>opts</var>, struct gcc_options *<var>opts_set</var>, const struct cl_decoded_option *<var>decoded</var>, location_t <var>loc</var>)</em></dt> +<dd><p>This hook is called whenever the user specifies one of the +target-specific options described by the <samp>.opt</samp> definition files +(see <a href="Options.html#Options">Options</a>). It has the opportunity to do some option-specific +processing and should return true if the option is valid. The default +definition does nothing but return true. +</p> +<p><var>decoded</var> specifies the option and its arguments. <var>opts</var> and +<var>opts_set</var> are the <code>gcc_options</code> structures to be used for +storing option state, and <var>loc</var> is the location at which the +option was passed (<code>UNKNOWN_LOCATION</code> except for options passed +via attributes). +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fHANDLE_005fC_005fOPTION"></a>C Target Hook: <em>bool</em> <strong>TARGET_HANDLE_C_OPTION</strong> <em>(size_t <var>code</var>, const char *<var>arg</var>, int <var>value</var>)</em></dt> +<dd><p>This target hook is called whenever the user specifies one of the +target-specific C language family options described by the <samp>.opt</samp> +definition files(see <a href="Options.html#Options">Options</a>). It has the opportunity to do some +option-specific processing and should return true if the option is +valid. The arguments are like for <code>TARGET_HANDLE_OPTION</code>. The +default definition does nothing but return false. +</p> +<p>In general, you should use <code>TARGET_HANDLE_OPTION</code> to handle +options. However, if processing an option requires routines that are +only available in the C (and related language) front ends, then you +should use <code>TARGET_HANDLE_C_OPTION</code> instead. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOBJC_005fCONSTRUCT_005fSTRING_005fOBJECT"></a>C Target Hook: <em>tree</em> <strong>TARGET_OBJC_CONSTRUCT_STRING_OBJECT</strong> <em>(tree <var>string</var>)</em></dt> +<dd><p>Targets may provide a string object type that can be used within +and between C, C++ and their respective Objective-C dialects. +A string object might, for example, embed encoding and length information. +These objects are considered opaque to the compiler and handled as references. +An ideal implementation makes the composition of the string object +match that of the Objective-C <code>NSString</code> (<code>NXString</code> for GNUStep), +allowing efficient interworking between C-only and Objective-C code. +If a target implements string objects then this hook should return a +reference to such an object constructed from the normal ‘C’ string +representation provided in <var>string</var>. +At present, the hook is used by Objective-C only, to obtain a + common-format string object when the target provides one. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOBJC_005fDECLARE_005fUNRESOLVED_005fCLASS_005fREFERENCE"></a>C Target Hook: <em>void</em> <strong>TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE</strong> <em>(const char *<var>classname</var>)</em></dt> +<dd><p>Declare that Objective C class <var>classname</var> is referenced +by the current TU. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOBJC_005fDECLARE_005fCLASS_005fDEFINITION"></a>C Target Hook: <em>void</em> <strong>TARGET_OBJC_DECLARE_CLASS_DEFINITION</strong> <em>(const char *<var>classname</var>)</em></dt> +<dd><p>Declare that Objective C class <var>classname</var> is defined +by the current TU. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fSTRING_005fOBJECT_005fREF_005fTYPE_005fP"></a>C Target Hook: <em>bool</em> <strong>TARGET_STRING_OBJECT_REF_TYPE_P</strong> <em>(const_tree <var>stringref</var>)</em></dt> +<dd><p>If a target implements string objects then this hook should return +<code>true</code> if <var>stringref</var> is a valid reference to such an object. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fCHECK_005fSTRING_005fOBJECT_005fFORMAT_005fARG"></a>C Target Hook: <em>void</em> <strong>TARGET_CHECK_STRING_OBJECT_FORMAT_ARG</strong> <em>(tree <var>format_arg</var>, tree <var>args_list</var>)</em></dt> +<dd><p>If a target implements string objects then this hook should +provide a facility to check the function arguments in <var>args_list</var> +against the format specifiers in <var>format_arg</var> where the type of +<var>format_arg</var> is one recognized as a valid string reference type. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOVERRIDE_005fOPTIONS_005fAFTER_005fCHANGE"></a>Target Hook: <em>void</em> <strong>TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE</strong> <em>(void)</em></dt> +<dd><p>This target function is similar to the hook <code>TARGET_OPTION_OVERRIDE</code> +but is called when the optimize level is changed via an attribute or +pragma or when it is reset at the end of the code affected by the +attribute or pragma. It is not called at the beginning of compilation +when <code>TARGET_OPTION_OVERRIDE</code> is called so if you want to perform these +actions then, you should have <code>TARGET_OPTION_OVERRIDE</code> call +<code>TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE</code>. +</p></dd></dl> + +<dl> +<dt><a name="index-C_005fCOMMON_005fOVERRIDE_005fOPTIONS"></a>Macro: <strong>C_COMMON_OVERRIDE_OPTIONS</strong></dt> +<dd><p>This is similar to the <code>TARGET_OPTION_OVERRIDE</code> hook +but is only used in the C +language frontends (C, Objective-C, C++, Objective-C++) and so can be +used to alter option flag variables which only exist in those +frontends. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOPTION_005fOPTIMIZATION_005fTABLE"></a>Common Target Hook: <em>const struct default_options *</em> <strong>TARGET_OPTION_OPTIMIZATION_TABLE</strong></dt> +<dd><p>Some machines may desire to change what optimizations are performed for +various optimization levels. This variable, if defined, describes +options to enable at particular sets of optimization levels. These +options are processed once +just after the optimization level is determined and before the remainder +of the command options have been parsed, so may be overridden by other +options passed explicitly. +</p> +<p>This processing is run once at program startup and when the optimization +options are changed via <code>#pragma GCC optimize</code> or by using the +<code>optimize</code> attribute. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOPTION_005fINIT_005fSTRUCT"></a>Common Target Hook: <em>void</em> <strong>TARGET_OPTION_INIT_STRUCT</strong> <em>(struct gcc_options *<var>opts</var>)</em></dt> +<dd><p>Set target-dependent initial values of fields in <var>opts</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fCOMPUTE_005fMULTILIB"></a>Common Target Hook: <em>const char *</em> <strong>TARGET_COMPUTE_MULTILIB</strong> <em>(const struct switchstr *<var>switches</var>, int <var>n_switches</var>, const char *<var>multilib_dir</var>, const char *<var>multilib_defaults</var>, const char *<var>multilib_select</var>, const char *<var>multilib_matches</var>, const char *<var>multilib_exclusions</var>, const char *<var>multilib_reuse</var>)</em></dt> +<dd><p>Some targets like RISC-V might have complicated multilib reuse rules which +are hard to implement with the current multilib scheme. This hook allows +targets to override the result from the built-in multilib mechanism. +<var>switches</var> is the raw option list with <var>n_switches</var> items; +<var>multilib_dir</var> is the multi-lib result which is computed by the built-in +multi-lib mechanism; +<var>multilib_defaults</var> is the default options list for multi-lib; +<var>multilib_select</var> is the string containing the list of supported +multi-libs, and the option checking list. +<var>multilib_matches</var>, <var>multilib_exclusions</var>, and <var>multilib_reuse</var> +are corresponding to <var>MULTILIB_MATCHES</var>, <var>MULTILIB_EXCLUSIONS</var>, +and <var>MULTILIB_REUSE</var>. +The default definition does nothing but return <var>multilib_dir</var> directly. +</p></dd></dl> + + +<dl> +<dt><a name="index-SWITCHABLE_005fTARGET"></a>Macro: <strong>SWITCHABLE_TARGET</strong></dt> +<dd><p>Some targets need to switch between substantially different subtargets +during compilation. For example, the MIPS target has one subtarget for +the traditional MIPS architecture and another for MIPS16. Source code +can switch between these two subarchitectures using the <code>mips16</code> +and <code>nomips16</code> attributes. +</p> +<p>Such subtargets can differ in things like the set of available +registers, the set of available instructions, the costs of various +operations, and so on. GCC caches a lot of this type of information +in global variables, and recomputing them for each subtarget takes a +significant amount of time. The compiler therefore provides a facility +for maintaining several versions of the global variables and quickly +switching between them; see <samp>target-globals.h</samp> for details. +</p> +<p>Define this macro to 1 if your target needs this facility. The default +is 0. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fFLOAT_005fEXCEPTIONS_005fROUNDING_005fSUPPORTED_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P</strong> <em>(void)</em></dt> +<dd><p>Returns true if the target supports IEEE 754 floating-point exceptions +and rounding modes, false otherwise. This is intended to relate to the +<code>float</code> and <code>double</code> types, but not necessarily <code>long double</code>. +By default, returns true if the <code>adddf3</code> instruction pattern is +available and false otherwise, on the assumption that hardware floating +point supports exceptions and rounding modes but software floating point +does not. +</p></dd></dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Per_002dFunction-Data.html#Per_002dFunction-Data" accesskey="n" rel="next">Per-Function Data</a>, Previous: <a href="Driver.html#Driver" accesskey="p" rel="previous">Driver</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> +</div> + + + +</body> +</html> |