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.
179 lines
8.0 KiB
HTML
179 lines
8.0 KiB
HTML
<html lang="en">
|
|
<head>
|
|
<title>CFI directives - Using as</title>
|
|
<meta http-equiv="Content-Type" content="text/html">
|
|
<meta name="description" content="Using as">
|
|
<meta name="generator" content="makeinfo 4.7">
|
|
<link title="Top" rel="start" href="index.html#Top">
|
|
<link rel="up" href="Pseudo-Ops.html#Pseudo-Ops" title="Pseudo Ops">
|
|
<link rel="prev" href="Comm.html#Comm" title="Comm">
|
|
<link rel="next" href="Data.html#Data" title="Data">
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
|
<!--
|
|
This file documents the GNU Assembler "as".
|
|
|
|
Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
|
|
2006, 2007 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 1.1
|
|
or any later version published by the Free Software Foundation;
|
|
with no Invariant Sections, with no Front-Cover Texts, and with no
|
|
Back-Cover Texts. A copy of the license is included in the
|
|
section entitled ``GNU Free Documentation License''.
|
|
|
|
man end-->
|
|
<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; }
|
|
--></style>
|
|
</head>
|
|
<body>
|
|
<div class="node">
|
|
<p>
|
|
<a name="CFI-directives"></a>Next: <a rel="next" accesskey="n" href="Data.html#Data">Data</a>,
|
|
Previous: <a rel="previous" accesskey="p" href="Comm.html#Comm">Comm</a>,
|
|
Up: <a rel="up" accesskey="u" href="Pseudo-Ops.html#Pseudo-Ops">Pseudo Ops</a>
|
|
<hr><br>
|
|
</div>
|
|
|
|
<h3 class="section">7.9 <code>.cfi_startproc [simple]</code></h3>
|
|
|
|
<p><a name="index-_0040code_007bcfi_005fstartproc_007d-directive-290"></a><code>.cfi_startproc</code> is used at the beginning of each function that
|
|
should have an entry in <code>.eh_frame</code>. It initializes some internal
|
|
data structures. Don't forget to close the function by
|
|
<code>.cfi_endproc</code>.
|
|
|
|
<p>Unless <code>.cfi_startproc</code> is used along with parameter <code>simple</code>
|
|
it also emits some architecture dependent initial CFI instructions.
|
|
|
|
<h3 class="section">7.10 <code>.cfi_endproc</code></h3>
|
|
|
|
<p><a name="index-_0040code_007bcfi_005fendproc_007d-directive-291"></a><code>.cfi_endproc</code> is used at the end of a function where it closes its
|
|
unwind entry previously opened by
|
|
<code>.cfi_startproc</code>, and emits it to <code>.eh_frame</code>.
|
|
|
|
<h3 class="section">7.11 <code>.cfi_personality </code><var>encoding</var><code> [, </code><var>exp</var><code>]</code></h3>
|
|
|
|
<p><code>.cfi_personality</code> defines personality routine and its encoding.
|
|
<var>encoding</var> must be a constant determining how the personality
|
|
should be encoded. If it is 255 (<code>DW_EH_PE_omit</code>), second
|
|
argument is not present, otherwise second argument should be
|
|
a constant or a symbol name. When using indirect encodings,
|
|
the symbol provided should be the location where personality
|
|
can be loaded from, not the personality routine itself.
|
|
The default after <code>.cfi_startproc</code> is <code>.cfi_personality 0xff</code>,
|
|
no personality routine.
|
|
|
|
<h3 class="section">7.12 <code>.cfi_lsda </code><var>encoding</var><code> [, </code><var>exp</var><code>]</code></h3>
|
|
|
|
<p><code>.cfi_lsda</code> defines LSDA and its encoding.
|
|
<var>encoding</var> must be a constant determining how the LSDA
|
|
should be encoded. If it is 255 (<code>DW_EH_PE_omit</code>), second
|
|
argument is not present, otherwise second argument should be a constant
|
|
or a symbol name. The default after <code>.cfi_startproc</code> is <code>.cfi_lsda 0xff</code>,
|
|
no LSDA.
|
|
|
|
<h3 class="section">7.13 <code>.cfi_def_cfa </code><var>register</var><code>, </code><var>offset</var></h3>
|
|
|
|
<p><code>.cfi_def_cfa</code> defines a rule for computing CFA as: <i>take
|
|
address from </i><var>register</var><i> and add </i><var>offset</var><i> to it</i>.
|
|
|
|
<h3 class="section">7.14 <code>.cfi_def_cfa_register </code><var>register</var></h3>
|
|
|
|
<p><code>.cfi_def_cfa_register</code> modifies a rule for computing CFA. From
|
|
now on <var>register</var> will be used instead of the old one. Offset
|
|
remains the same.
|
|
|
|
<h3 class="section">7.15 <code>.cfi_def_cfa_offset </code><var>offset</var></h3>
|
|
|
|
<p><code>.cfi_def_cfa_offset</code> modifies a rule for computing CFA. Register
|
|
remains the same, but <var>offset</var> is new. Note that it is the
|
|
absolute offset that will be added to a defined register to compute
|
|
CFA address.
|
|
|
|
<h3 class="section">7.16 <code>.cfi_adjust_cfa_offset </code><var>offset</var></h3>
|
|
|
|
<p>Same as <code>.cfi_def_cfa_offset</code> but <var>offset</var> is a relative
|
|
value that is added/substracted from the previous offset.
|
|
|
|
<h3 class="section">7.17 <code>.cfi_offset </code><var>register</var><code>, </code><var>offset</var></h3>
|
|
|
|
<p>Previous value of <var>register</var> is saved at offset <var>offset</var> from
|
|
CFA.
|
|
|
|
<h3 class="section">7.18 <code>.cfi_rel_offset </code><var>register</var><code>, </code><var>offset</var></h3>
|
|
|
|
<p>Previous value of <var>register</var> is saved at offset <var>offset</var> from
|
|
the current CFA register. This is transformed to <code>.cfi_offset</code>
|
|
using the known displacement of the CFA register from the CFA.
|
|
This is often easier to use, because the number will match the
|
|
code it's annotating.
|
|
|
|
<h3 class="section">7.19 <code>.cfi_register </code><var>register1</var><code>, </code><var>register2</var></h3>
|
|
|
|
<p>Previous value of <var>register1</var> is saved in register <var>register2</var>.
|
|
|
|
<h3 class="section">7.20 <code>.cfi_restore </code><var>register</var></h3>
|
|
|
|
<p><code>.cfi_restore</code> says that the rule for <var>register</var> is now the
|
|
same as it was at the beginning of the function, after all initial
|
|
instruction added by <code>.cfi_startproc</code> were executed.
|
|
|
|
<h3 class="section">7.21 <code>.cfi_undefined </code><var>register</var></h3>
|
|
|
|
<p>From now on the previous value of <var>register</var> can't be restored anymore.
|
|
|
|
<h3 class="section">7.22 <code>.cfi_same_value </code><var>register</var></h3>
|
|
|
|
<p>Current value of <var>register</var> is the same like in the previous frame,
|
|
i.e. no restoration needed.
|
|
|
|
<h3 class="section">7.23 <code>.cfi_remember_state</code>,</h3>
|
|
|
|
<p>First save all current rules for all registers by <code>.cfi_remember_state</code>,
|
|
then totally screw them up by subsequent <code>.cfi_*</code> directives and when
|
|
everything is hopelessly bad, use <code>.cfi_restore_state</code> to restore
|
|
the previous saved state.
|
|
|
|
<h3 class="section">7.24 <code>.cfi_return_column </code><var>register</var></h3>
|
|
|
|
<p>Change return column <var>register</var>, i.e. the return address is either
|
|
directly in <var>register</var> or can be accessed by rules for <var>register</var>.
|
|
|
|
<h3 class="section">7.25 <code>.cfi_signal_frame</code></h3>
|
|
|
|
<p>Mark current function as signal trampoline.
|
|
|
|
<h3 class="section">7.26 <code>.cfi_window_save</code></h3>
|
|
|
|
<p>SPARC register window has been saved.
|
|
|
|
<h3 class="section">7.27 <code>.cfi_escape</code> <var>expression</var>[, <small class="dots">...</small>]</h3>
|
|
|
|
<p>Allows the user to add arbitrary bytes to the unwind info. One
|
|
might use this to add OS-specific CFI opcodes, or generic CFI
|
|
opcodes that GAS does not yet support.
|
|
|
|
<h3 class="section">7.28 <code>.cfi_val_encoded_addr </code><var>register</var><code>, </code><var>encoding</var><code>, </code><var>label</var></h3>
|
|
|
|
<p>The current value of <var>register</var> is <var>label</var>. The value of <var>label</var>
|
|
will be encoded in the output file according to <var>encoding</var>; see the
|
|
description of <code>.cfi_personality</code> for details on this encoding.
|
|
|
|
<p>The usefulness of equating a register to a fixed label is probably
|
|
limited to the return address register. Here, it can be useful to
|
|
mark a code segment that has only one return address which is reached
|
|
by a direct branch and no copy of the return address exists in memory
|
|
or another register.
|
|
|
|
</body></html>
|
|
|