| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html> |
| <!-- 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 "Free Software" and "Free Software Needs |
| Free Documentation", with the Front-Cover Texts being "A GNU Manual," |
| and with the Back-Cover Texts as in (a) below. |
| |
| (a) The FSF's Back-Cover Text is: "You are free to copy and modify |
| this GNU Manual. Buying copies from GNU Press supports the FSF in |
| developing GNU and promoting software freedom." --> |
| <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ --> |
| <head> |
| <title>Debugging with GDB: JIT Interface</title> |
| |
| <meta name="description" content="Debugging with GDB: JIT Interface"> |
| <meta name="keywords" content="Debugging with GDB: JIT Interface"> |
| <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="Concept-Index.html#Concept-Index" rel="index" title="Concept Index"> |
| <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> |
| <link href="index.html#Top" rel="up" title="Top"> |
| <link href="Declarations.html#Declarations" rel="next" title="Declarations"> |
| <link href="Source-Annotations.html#Source-Annotations" rel="prev" title="Source Annotations"> |
| <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="JIT-Interface"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="In_002dProcess-Agent.html#In_002dProcess-Agent" accesskey="n" rel="next">In-Process Agent</a>, Previous: <a href="Annotations.html#Annotations" accesskey="p" rel="prev">Annotations</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <hr> |
| <a name="JIT-Compilation-Interface"></a> |
| <h2 class="chapter">29 JIT Compilation Interface</h2> |
| <a name="index-just_002din_002dtime-compilation"></a> |
| <a name="index-JIT-compilation-interface"></a> |
| |
| <p>This chapter documents <small>GDB</small>’s <em>just-in-time</em> (JIT) compilation |
| interface. A JIT compiler is a program or library that generates native |
| executable code at runtime and executes it, usually in order to achieve good |
| performance while maintaining platform independence. |
| </p> |
| <p>Programs that use JIT compilation are normally difficult to debug because |
| portions of their code are generated at runtime, instead of being loaded from |
| object files, which is where <small>GDB</small> normally finds the program’s symbols |
| and debug information. In order to debug programs that use JIT compilation, |
| <small>GDB</small> has an interface that allows the program to register in-memory |
| symbol files with <small>GDB</small> at runtime. |
| </p> |
| <p>If you are using <small>GDB</small> to debug a program that uses this interface, then |
| it should work transparently so long as you have not stripped the binary. If |
| you are developing a JIT compiler, then the interface is documented in the rest |
| of this chapter. At this time, the only known client of this interface is the |
| LLVM JIT. |
| </p> |
| <p>Broadly speaking, the JIT interface mirrors the dynamic loader interface. The |
| JIT compiler communicates with <small>GDB</small> by writing data into a global |
| variable and calling a fuction at a well-known symbol. When <small>GDB</small> |
| attaches, it reads a linked list of symbol files from the global variable to |
| find existing code, and puts a breakpoint in the function so that it can find |
| out about additional code. |
| </p> |
| <table class="menu" border="0" cellspacing="0"> |
| <tr><td align="left" valign="top">• <a href="Declarations.html#Declarations" accesskey="1">Declarations</a>:</td><td> </td><td align="left" valign="top">Relevant C struct declarations |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Registering-Code.html#Registering-Code" accesskey="2">Registering Code</a>:</td><td> </td><td align="left" valign="top">Steps to register code |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Unregistering-Code.html#Unregistering-Code" accesskey="3">Unregistering Code</a>:</td><td> </td><td align="left" valign="top">Steps to unregister code |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Custom-Debug-Info.html#Custom-Debug-Info" accesskey="4">Custom Debug Info</a>:</td><td> </td><td align="left" valign="top">Emit debug information in a custom format |
| </td></tr> |
| </table> |
| |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="In_002dProcess-Agent.html#In_002dProcess-Agent" accesskey="n" rel="next">In-Process Agent</a>, Previous: <a href="Annotations.html#Annotations" accesskey="p" rel="prev">Annotations</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> |
| </div> |
| |
| |
| |
| </body> |
| </html> |
