diff options
| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
|---|---|---|
| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gccint/Target-Attributes.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
Diffstat (limited to 'share/doc/gccint/Target-Attributes.html')
| -rw-r--r-- | share/doc/gccint/Target-Attributes.html | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/share/doc/gccint/Target-Attributes.html b/share/doc/gccint/Target-Attributes.html new file mode 100644 index 0000000..87af23a --- /dev/null +++ b/share/doc/gccint/Target-Attributes.html @@ -0,0 +1,333 @@ +<!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: Target Attributes</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Target Attributes"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Target Attributes"> +<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="Emulated-TLS.html#Emulated-TLS" rel="next" title="Emulated TLS"> +<link href="Mode-Switching.html#Mode-Switching" rel="previous" title="Mode Switching"> +<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="Target-Attributes"></a> +<div class="header"> +<p> +Next: <a href="Emulated-TLS.html#Emulated-TLS" accesskey="n" rel="next">Emulated TLS</a>, Previous: <a href="Mode-Switching.html#Mode-Switching" accesskey="p" rel="previous">Mode Switching</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="Defining-target_002dspecific-uses-of-_005f_005fattribute_005f_005f"></a> +<h3 class="section">18.24 Defining target-specific uses of <code>__attribute__</code></h3> +<a name="index-target-attributes"></a> +<a name="index-machine-attributes"></a> +<a name="index-attributes_002c-target_002dspecific"></a> + +<p>Target-specific attributes may be defined for functions, data and types. +These are described using the following target hooks; they also need to +be documented in <samp>extend.texi</samp>. +</p> +<dl> +<dt><a name="index-TARGET_005fATTRIBUTE_005fTABLE"></a>Target Hook: <em>const struct attribute_spec *</em> <strong>TARGET_ATTRIBUTE_TABLE</strong></dt> +<dd><p>If defined, this target hook points to an array of ‘<samp>struct +attribute_spec</samp>’ (defined in <samp>tree-core.h</samp>) specifying the machine +specific attributes for this target and some of the restrictions on the +entities to which these attributes are applied and the arguments they +take. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fATTRIBUTE_005fTAKES_005fIDENTIFIER_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P</strong> <em>(const_tree <var>name</var>)</em></dt> +<dd><p>If defined, this target hook is a function which returns true if the +machine-specific attribute named <var>name</var> expects an identifier +given as its first argument to be passed on as a plain identifier, not +subjected to name lookup. If this is not defined, the default is +false for all machine-specific attributes. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fCOMP_005fTYPE_005fATTRIBUTES"></a>Target Hook: <em>int</em> <strong>TARGET_COMP_TYPE_ATTRIBUTES</strong> <em>(const_tree <var>type1</var>, const_tree <var>type2</var>)</em></dt> +<dd><p>If defined, this target hook is a function which returns zero if the attributes on +<var>type1</var> and <var>type2</var> are incompatible, one if they are compatible, +and two if they are nearly compatible (which causes a warning to be +generated). If this is not defined, machine-specific attributes are +supposed always to be compatible. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fSET_005fDEFAULT_005fTYPE_005fATTRIBUTES"></a>Target Hook: <em>void</em> <strong>TARGET_SET_DEFAULT_TYPE_ATTRIBUTES</strong> <em>(tree <var>type</var>)</em></dt> +<dd><p>If defined, this target hook is a function which assigns default attributes to +the newly defined <var>type</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fMERGE_005fTYPE_005fATTRIBUTES"></a>Target Hook: <em>tree</em> <strong>TARGET_MERGE_TYPE_ATTRIBUTES</strong> <em>(tree <var>type1</var>, tree <var>type2</var>)</em></dt> +<dd><p>Define this target hook if the merging of type attributes needs special +handling. If defined, the result is a list of the combined +<code>TYPE_ATTRIBUTES</code> of <var>type1</var> and <var>type2</var>. It is assumed +that <code>comptypes</code> has already been called and returned 1. This +function may call <code>merge_attributes</code> to handle machine-independent +merging. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fMERGE_005fDECL_005fATTRIBUTES"></a>Target Hook: <em>tree</em> <strong>TARGET_MERGE_DECL_ATTRIBUTES</strong> <em>(tree <var>olddecl</var>, tree <var>newdecl</var>)</em></dt> +<dd><p>Define this target hook if the merging of decl attributes needs special +handling. If defined, the result is a list of the combined +<code>DECL_ATTRIBUTES</code> of <var>olddecl</var> and <var>newdecl</var>. +<var>newdecl</var> is a duplicate declaration of <var>olddecl</var>. Examples of +when this is needed are when one attribute overrides another, or when an +attribute is nullified by a subsequent definition. This function may +call <code>merge_attributes</code> to handle machine-independent merging. +</p> +<a name="index-TARGET_005fDLLIMPORT_005fDECL_005fATTRIBUTES"></a> +<p>If the only target-specific handling you require is ‘<samp>dllimport</samp>’ +for Microsoft Windows targets, you should define the macro +<code>TARGET_DLLIMPORT_DECL_ATTRIBUTES</code> to <code>1</code>. The compiler +will then define a function called +<code>merge_dllimport_decl_attributes</code> which can then be defined as +the expansion of <code>TARGET_MERGE_DECL_ATTRIBUTES</code>. You can also +add <code>handle_dll_attribute</code> in the attribute table for your port +to perform initial processing of the ‘<samp>dllimport</samp>’ and +‘<samp>dllexport</samp>’ attributes. This is done in <samp>i386/cygwin.h</samp> and +<samp>i386/i386.cc</samp>, for example. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fVALID_005fDLLIMPORT_005fATTRIBUTE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_VALID_DLLIMPORT_ATTRIBUTE_P</strong> <em>(const_tree <var>decl</var>)</em></dt> +<dd><p><var>decl</var> is a variable or function with <code>__attribute__((dllimport))</code> +specified. Use this hook if the target needs to add extra validation +checks to <code>handle_dll_attribute</code>. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fDECLSPEC"></a>Macro: <strong>TARGET_DECLSPEC</strong></dt> +<dd><p>Define this macro to a nonzero value if you want to treat +<code>__declspec(X)</code> as equivalent to <code>__attribute((X))</code>. By +default, this behavior is enabled only for targets that define +<code>TARGET_DLLIMPORT_DECL_ATTRIBUTES</code>. The current implementation +of <code>__declspec</code> is via a built-in macro, but you should not rely +on this implementation detail. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fINSERT_005fATTRIBUTES"></a>Target Hook: <em>void</em> <strong>TARGET_INSERT_ATTRIBUTES</strong> <em>(tree <var>node</var>, tree *<var>attr_ptr</var>)</em></dt> +<dd><p>Define this target hook if you want to be able to add attributes to a decl +when it is being created. This is normally useful for back ends which +wish to implement a pragma by using the attributes which correspond to +the pragma’s effect. The <var>node</var> argument is the decl which is being +created. The <var>attr_ptr</var> argument is a pointer to the attribute list +for this decl. The list itself should not be modified, since it may be +shared with other decls, but attributes may be chained on the head of +the list and <code>*<var>attr_ptr</var></code> modified to point to the new +attributes, or a copy of the list may be made if further changes are +needed. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fHANDLE_005fGENERIC_005fATTRIBUTE"></a>Target Hook: <em>tree</em> <strong>TARGET_HANDLE_GENERIC_ATTRIBUTE</strong> <em>(tree *<var>node</var>, tree <var>name</var>, tree <var>args</var>, int <var>flags</var>, bool *<var>no_add_attrs</var>)</em></dt> +<dd><p>Define this target hook if you want to be able to perform additional +target-specific processing of an attribute which is handled generically +by a front end. The arguments are the same as those which are passed to +attribute handlers. So far this only affects the <var>noinit</var> and +<var>section</var> attribute. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fFUNCTION_005fATTRIBUTE_005fINLINABLE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P</strong> <em>(const_tree <var>fndecl</var>)</em></dt> +<dd><a name="index-inlining"></a> +<p>This target hook returns <code>true</code> if it is OK to inline <var>fndecl</var> +into the current function, despite its having target-specific +attributes, <code>false</code> otherwise. By default, if a function has a +target specific attribute attached to it, it will not be inlined. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOPTION_005fVALID_005fATTRIBUTE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_OPTION_VALID_ATTRIBUTE_P</strong> <em>(tree <var>fndecl</var>, tree <var>name</var>, tree <var>args</var>, int <var>flags</var>)</em></dt> +<dd><p>This hook is called to parse <code>attribute(target("..."))</code>, which +allows setting target-specific options on individual functions. +These function-specific options may differ +from the options specified on the command line. The hook should return +<code>true</code> if the options are valid. +</p> +<p>The hook should set the <code>DECL_FUNCTION_SPECIFIC_TARGET</code> field in +the function declaration to hold a pointer to a target-specific +<code>struct cl_target_option</code> structure. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOPTION_005fSAVE"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_SAVE</strong> <em>(struct cl_target_option *<var>ptr</var>, struct gcc_options *<var>opts</var>, struct gcc_options *<var>opts_set</var>)</em></dt> +<dd><p>This hook is called to save any additional target-specific information +in the <code>struct cl_target_option</code> structure for function-specific +options from the <code>struct gcc_options</code> structure. +See <a href="Option-file-format.html#Option-file-format">Option file format</a>. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOPTION_005fRESTORE"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_RESTORE</strong> <em>(struct gcc_options *<var>opts</var>, struct gcc_options *<var>opts_set</var>, struct cl_target_option *<var>ptr</var>)</em></dt> +<dd><p>This hook is called to restore any additional target-specific +information in the <code>struct cl_target_option</code> structure for +function-specific options to the <code>struct gcc_options</code> structure. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOPTION_005fPOST_005fSTREAM_005fIN"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_POST_STREAM_IN</strong> <em>(struct cl_target_option *<var>ptr</var>)</em></dt> +<dd><p>This hook is called to update target-specific information in the +<code>struct cl_target_option</code> structure after it is streamed in from +LTO bytecode. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOPTION_005fPRINT"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_PRINT</strong> <em>(FILE *<var>file</var>, int <var>indent</var>, struct cl_target_option *<var>ptr</var>)</em></dt> +<dd><p>This hook is called to print any additional target-specific +information in the <code>struct cl_target_option</code> structure for +function-specific options. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOPTION_005fPRAGMA_005fPARSE"></a>Target Hook: <em>bool</em> <strong>TARGET_OPTION_PRAGMA_PARSE</strong> <em>(tree <var>args</var>, tree <var>pop_target</var>)</em></dt> +<dd><p>This target hook parses the options for <code>#pragma GCC target</code>, which +sets the target-specific options for functions that occur later in the +input stream. The options accepted should be the same as those handled by the +<code>TARGET_OPTION_VALID_ATTRIBUTE_P</code> hook. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOPTION_005fOVERRIDE"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_OVERRIDE</strong> <em>(void)</em></dt> +<dd><p>Sometimes certain combinations of command options do not make sense on +a particular target machine. You can override the hook +<code>TARGET_OPTION_OVERRIDE</code> to take account of this. This hooks is called +once just after all the command options have been parsed. +</p> +<p>Don’t use this hook to turn on various extra optimizations for +<samp>-O</samp>. That is what <code>TARGET_OPTION_OPTIMIZATION</code> is for. +</p> +<p>If you need to do something whenever the optimization level is +changed via the optimize attribute or pragma, see +<code>TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE</code> +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fOPTION_005fFUNCTION_005fVERSIONS"></a>Target Hook: <em>bool</em> <strong>TARGET_OPTION_FUNCTION_VERSIONS</strong> <em>(tree <var>decl1</var>, tree <var>decl2</var>)</em></dt> +<dd><p>This target hook returns <code>true</code> if <var>DECL1</var> and <var>DECL2</var> are +versions of the same function. <var>DECL1</var> and <var>DECL2</var> are function +versions if and only if they have the same function signature and +different target specific attributes, that is, they are compiled for +different target machines. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fCAN_005fINLINE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_CAN_INLINE_P</strong> <em>(tree <var>caller</var>, tree <var>callee</var>)</em></dt> +<dd><p>This target hook returns <code>false</code> if the <var>caller</var> function +cannot inline <var>callee</var>, based on target specific information. By +default, inlining is not allowed if the callee function has function +specific target options and the caller does not use the same options. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fUPDATE_005fIPA_005fFN_005fTARGET_005fINFO"></a>Target Hook: <em>bool</em> <strong>TARGET_UPDATE_IPA_FN_TARGET_INFO</strong> <em>(unsigned int& <var>info</var>, const gimple* <var>stmt</var>)</em></dt> +<dd><p>Allow target to analyze all gimple statements for the given function to +record and update some target specific information for inlining. A typical +example is that a caller with one isa feature disabled is normally not +allowed to inline a callee with that same isa feature enabled even which is +attributed by always_inline, but with the conservative analysis on all +statements of the callee if we are able to guarantee the callee does not +exploit any instructions from the mismatch isa feature, it would be safe to +allow the caller to inline the callee. +<var>info</var> is one <code>unsigned int</code> value to record information in which +one set bit indicates one corresponding feature is detected in the analysis, +<var>stmt</var> is the statement being analyzed. Return true if target still +need to analyze the subsequent statements, otherwise return false to stop +subsequent analysis. +The default version of this hook returns false. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fNEED_005fIPA_005fFN_005fTARGET_005fINFO"></a>Target Hook: <em>bool</em> <strong>TARGET_NEED_IPA_FN_TARGET_INFO</strong> <em>(const_tree <var>decl</var>, unsigned int& <var>info</var>)</em></dt> +<dd><p>Allow target to check early whether it is necessary to analyze all gimple +statements in the given function to update target specific information for +inlining. See hook <code>update_ipa_fn_target_info</code> for usage example of +target specific information. This hook is expected to be invoked ahead of +the iterating with hook <code>update_ipa_fn_target_info</code>. +<var>decl</var> is the function being analyzed, <var>info</var> is the same as what +in hook <code>update_ipa_fn_target_info</code>, target can do one time update +into <var>info</var> without iterating for some case. Return true if target +decides to analyze all gimple statements to collect information, otherwise +return false. +The default version of this hook returns false. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fRELAYOUT_005fFUNCTION"></a>Target Hook: <em>void</em> <strong>TARGET_RELAYOUT_FUNCTION</strong> <em>(tree <var>fndecl</var>)</em></dt> +<dd><p>This target hook fixes function <var>fndecl</var> after attributes are processed. +Default does nothing. On ARM, the default function’s alignment is updated +with the attribute target. +</p></dd></dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Emulated-TLS.html#Emulated-TLS" accesskey="n" rel="next">Emulated TLS</a>, Previous: <a href="Mode-Switching.html#Mode-Switching" accesskey="p" rel="previous">Mode Switching</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> |