📄 asm-labels.html
字号:
<html lang="en"><head><title>Using the GNU Compiler Collection (GCC)</title><meta http-equiv="Content-Type" content="text/html"><meta name="description" content="Using the GNU Compiler Collection (GCC)"><meta name="generator" content="makeinfo 4.6"><!--Copyright © 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. <p>Permission is granted to copy, distribute and/or modify this documentunder the terms of the GNU Free Documentation License, Version 1.2 orany later version published by the Free Software Foundation; with theInvariant Sections being "GNU General Public License" and "FundingFree Software", the Front-Cover texts being (a) (see below), and withthe Back-Cover Texts being (b) (see below). A copy of the license isincluded in the section entitled "GNU Free Documentation License". <p>(a) The FSF's Front-Cover Text is: <p>A GNU Manual <p>(b) The FSF's Back-Cover Text is: <p>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 }--></style></head><body><div class="node"><p>Node: <a name="Asm%20Labels">Asm Labels</a>,Next: <a rel="next" accesskey="n" href="Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>,Previous: <a rel="previous" accesskey="p" href="Constraints.html#Constraints">Constraints</a>,Up: <a rel="up" accesskey="u" href="C-Extensions.html#C%20Extensions">C Extensions</a><hr><br></div><h3 class="section">Controlling Names Used in Assembler Code</h3><p>You can specify the name to be used in the assembler code for a Cfunction or variable by writing the <code>asm</code> (or <code>__asm__</code>)keyword after the declarator as follows:<pre class="smallexample"> int foo asm ("myfoo") = 2; </pre><p>This specifies that the name to be used for the variable <code>foo</code> inthe assembler code should be <code>myfoo</code> rather than the usual<code>_foo</code>. <p>On systems where an underscore is normally prepended to the name of a Cfunction or variable, this feature allows you to define names for thelinker that do not start with an underscore. <p>It does not make sense to use this feature with a non-static localvariable since such variables do not have assembler names. If you aretrying to put the variable in a particular register, see <a href="Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>. GCC presently accepts such code with a warning, but willprobably be changed to issue an error, rather than a warning, in thefuture. <p>You cannot use <code>asm</code> in this way in a function <em>definition</em>; butyou can get the same effect by writing a declaration for the functionbefore its definition and putting <code>asm</code> there, like this:<pre class="smallexample"> extern func () asm ("FUNC"); func (x, y) int x, y; /* <small class="dots">...</small> */ </pre> <p>It is up to you to make sure that the assembler names you choose do notconflict with any other assembler symbols. Also, you must not use aregister name; that would produce completely invalid assembler code. GCCdoes not as yet have the ability to store static variables in registers. Perhaps that will be added. </body></html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -