You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
248 lines
14 KiB
HTML
248 lines
14 KiB
HTML
4 years ago
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<title>Target Attributes - GNU Compiler Collection (GCC) Internals</title>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html">
|
||
|
|
<meta name="description" content="GNU Compiler Collection (GCC) Internals">
|
||
|
|
<meta name="generator" content="makeinfo 4.13">
|
||
|
|
<link title="Top" rel="start" href="index.html#Top">
|
||
|
|
<link rel="up" href="Target-Macros.html#Target-Macros" title="Target Macros">
|
||
|
|
<link rel="prev" href="Mode-Switching.html#Mode-Switching" title="Mode Switching">
|
||
|
|
<link rel="next" href="Emulated-TLS.html#Emulated-TLS" title="Emulated TLS">
|
||
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
||
|
|
<!--
|
||
|
|
Copyright (C) 1988-2015 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.-->
|
||
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
||
|
|
<style type="text/css"><!--
|
||
|
|
pre.display { font-family:inherit }
|
||
|
|
pre.format { font-family:inherit }
|
||
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallexample { font-size:smaller }
|
||
|
|
pre.smalllisp { font-size:smaller }
|
||
|
|
span.sc { font-variant:small-caps }
|
||
|
|
span.roman { font-family:serif; font-weight:normal; }
|
||
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
||
|
|
--></style>
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
<div class="node">
|
||
|
|
<a name="Target-Attributes"></a>
|
||
|
|
<p>
|
||
|
|
Next: <a rel="next" accesskey="n" href="Emulated-TLS.html#Emulated-TLS">Emulated TLS</a>,
|
||
|
|
Previous: <a rel="previous" accesskey="p" href="Mode-Switching.html#Mode-Switching">Mode Switching</a>,
|
||
|
|
Up: <a rel="up" accesskey="u" href="Target-Macros.html#Target-Macros">Target Macros</a>
|
||
|
|
<hr>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<h3 class="section">17.24 Defining target-specific uses of <code>__attribute__</code></h3>
|
||
|
|
|
||
|
|
<p><a name="index-target-attributes-4827"></a><a name="index-machine-attributes-4828"></a><a name="index-attributes_002c-target_002dspecific-4829"></a>
|
||
|
|
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><span class="file">extend.texi</span></samp>.
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: const struct attribute_spec * <b>TARGET_ATTRIBUTE_TABLE</b><var><a name="index-TARGET_005fATTRIBUTE_005fTABLE-4830"></a></var><br>
|
||
|
|
<blockquote><p>If defined, this target hook points to an array of ‘<samp><span class="samp">struct
|
||
|
|
attribute_spec</span></samp>’ (defined in <samp><span class="file">tree.h</span></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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: bool <b>TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P</b> (<var>const_tree name</var>)<var><a name="index-TARGET_005fATTRIBUTE_005fTAKES_005fIDENTIFIER_005fP-4831"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: int <b>TARGET_COMP_TYPE_ATTRIBUTES</b> (<var>const_tree type1, const_tree type2</var>)<var><a name="index-TARGET_005fCOMP_005fTYPE_005fATTRIBUTES-4832"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: void <b>TARGET_SET_DEFAULT_TYPE_ATTRIBUTES</b> (<var>tree type</var>)<var><a name="index-TARGET_005fSET_005fDEFAULT_005fTYPE_005fATTRIBUTES-4833"></a></var><br>
|
||
|
|
<blockquote><p>If defined, this target hook is a function which assigns default attributes to
|
||
|
|
the newly defined <var>type</var>.
|
||
|
|
</p></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: tree <b>TARGET_MERGE_TYPE_ATTRIBUTES</b> (<var>tree type1, tree type2</var>)<var><a name="index-TARGET_005fMERGE_005fTYPE_005fATTRIBUTES-4834"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: tree <b>TARGET_MERGE_DECL_ATTRIBUTES</b> (<var>tree olddecl, tree newdecl</var>)<var><a name="index-TARGET_005fMERGE_005fDECL_005fATTRIBUTES-4835"></a></var><br>
|
||
|
|
<blockquote><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-4836"></a>If the only target-specific handling you require is ‘<samp><span class="samp">dllimport</span></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><span class="samp">dllimport</span></samp>’ and
|
||
|
|
‘<samp><span class="samp">dllexport</span></samp>’ attributes. This is done in <samp><span class="file">i386/cygwin.h</span></samp> and
|
||
|
|
<samp><span class="file">i386/i386.c</span></samp>, for example.
|
||
|
|
</p></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: bool <b>TARGET_VALID_DLLIMPORT_ATTRIBUTE_P</b> (<var>const_tree decl</var>)<var><a name="index-TARGET_005fVALID_005fDLLIMPORT_005fATTRIBUTE_005fP-4837"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Macro: <b>TARGET_DECLSPEC</b><var><a name="index-TARGET_005fDECLSPEC-4838"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: void <b>TARGET_INSERT_ATTRIBUTES</b> (<var>tree node, tree *attr_ptr</var>)<var><a name="index-TARGET_005fINSERT_005fATTRIBUTES-4839"></a></var><br>
|
||
|
|
<blockquote><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>*</code><var>attr_ptr</var> modified to point to the new
|
||
|
|
attributes, or a copy of the list may be made if further changes are
|
||
|
|
needed.
|
||
|
|
</p></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: bool <b>TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P</b> (<var>const_tree fndecl</var>)<var><a name="index-TARGET_005fFUNCTION_005fATTRIBUTE_005fINLINABLE_005fP-4840"></a></var><br>
|
||
|
|
<blockquote><p><a name="index-inlining-4841"></a>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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: bool <b>TARGET_OPTION_VALID_ATTRIBUTE_P</b> (<var>tree fndecl, tree name, tree args, int flags</var>)<var><a name="index-TARGET_005fOPTION_005fVALID_005fATTRIBUTE_005fP-4842"></a></var><br>
|
||
|
|
<blockquote><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>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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: void <b>TARGET_OPTION_SAVE</b> (<var>struct cl_target_option *ptr, struct gcc_options *opts</var>)<var><a name="index-TARGET_005fOPTION_005fSAVE-4843"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: void <b>TARGET_OPTION_RESTORE</b> (<var>struct gcc_options *opts, struct cl_target_option *ptr</var>)<var><a name="index-TARGET_005fOPTION_005fRESTORE-4844"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: void <b>TARGET_OPTION_POST_STREAM_IN</b> (<var>struct cl_target_option *ptr</var>)<var><a name="index-TARGET_005fOPTION_005fPOST_005fSTREAM_005fIN-4845"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: void <b>TARGET_OPTION_PRINT</b> (<var>FILE *file, int indent, struct cl_target_option *ptr</var>)<var><a name="index-TARGET_005fOPTION_005fPRINT-4846"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: bool <b>TARGET_OPTION_PRAGMA_PARSE</b> (<var>tree args, tree pop_target</var>)<var><a name="index-TARGET_005fOPTION_005fPRAGMA_005fPARSE-4847"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: void <b>TARGET_OPTION_OVERRIDE</b> (<var>void</var>)<var><a name="index-TARGET_005fOPTION_005fOVERRIDE-4848"></a></var><br>
|
||
|
|
<blockquote><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>Don't use this hook to turn on various extra optimizations for
|
||
|
|
<samp><span class="option">-O</span></samp>. That is what <code>TARGET_OPTION_OPTIMIZATION</code> is for.
|
||
|
|
|
||
|
|
<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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: bool <b>TARGET_OPTION_FUNCTION_VERSIONS</b> (<var>tree decl1, tree decl2</var>)<var><a name="index-TARGET_005fOPTION_005fFUNCTION_005fVERSIONS-4849"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
<div class="defun">
|
||
|
|
— Target Hook: bool <b>TARGET_CAN_INLINE_P</b> (<var>tree caller, tree callee</var>)<var><a name="index-TARGET_005fCAN_005fINLINE_005fP-4850"></a></var><br>
|
||
|
|
<blockquote><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></blockquote></div>
|
||
|
|
|
||
|
|
</body></html>
|
||
|
|
|