1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>3.7.�ARM Profiling Implementation</title><link rel="stylesheet" type="text/css" href="cs.css"><meta name="generator" content="DocBook XSL Stylesheets V1.78.0"><link rel="home" href="index.html" title="Sourcery CodeBench Lite"><link rel="up" href="chap-target.html" title="Chapter�3.�Sourcery CodeBench Lite for ARM EABI"><link rel="prev" href="ch03s06.html" title="3.6.�ABI Compatibility"><link rel="next" href="portable-objects.html" title="3.8.�Object File Portability"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">3.7.�ARM Profiling Implementation</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch03s06.html">Prev</a>�</td><th width="60%" align="center">Chapter�3.�Sourcery CodeBench Lite for ARM EABI</th><td width="20%" align="right">�<a accesskey="n" href="portable-objects.html">Next</a></td></tr></table><hr></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="arm-mcount"></a>3.7.�ARM Profiling Implementation</h2></div></div></div><p> 2 Profiling is enabled by means of the <code class="option">-pg</code> 3 compiler option. In this mode, the compiler inserts a call to 4 <code class="function">__gnu_mcount_nc</code> into every function prologue. 5 However, no implementation of <code class="function">__gnu_mcount_nc</code> 6 is provided (to do so would be impossible without knowledge of 7 the execution environment). 8 </p><p> 9 You must provide your own implementation of 10 <code class="function">__gnu_mcount_nc </code>. Here are the requirements: 11 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"> 12 On exit, pop the top value from the stack, and place it in the 13 <code class="code">lr</code> register. The <code class="code">sp</code> register should 14 be adjusted accordingly. For example, this is how to write it 15 as a stub function: 16 <div class="informalexample"><pre class="programlisting"> .globl __gnu_mcount_nc 17 .type __gnu_mcount_nc, %function 18__gnu_mcount_nc: 19 mov ip, lr 20 pop { lr } 21 bx ip</pre></div></li><li class="listitem"> 22 Preserve all other register state except for <code class="code">r12</code> 23 and the CPSR condition code bits. In particular all coprocessor 24 state and registers <code class="code">r0</code>-<code class="code">r3</code> must 25 be preserved. 26 </li><li class="listitem"> 27 Record and count all occurrences of the function calls 28 in the program. The caller can be determined from the 29 <code class="code">lr</code> value stored on the top of the stack (on entry 30 to <code class="function">__gnu_mcount_nc</code>), and the callee can 31 be determined from the current value of the <code class="code">lr</code> 32 register (i.e. the caller of this function). 33 </li><li class="listitem"> 34 Arrange for the data to be saved to a file named 35 <code class="filename">gmon.out</code> when the program exits 36 (via <code class="function">atexit</code>). Refer to the 37 <code class="command">gprof</code> profiler manual for more information. 38 </li></ul></div><p> 39 </p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch03s06.html">Prev</a>�</td><td width="20%" align="center"><a accesskey="u" href="chap-target.html">Up</a></td><td width="40%" align="right">�<a accesskey="n" href="portable-objects.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">3.6.�ABI Compatibility�</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">�3.8.�Object File Portability</td></tr></table></div></body></html> 40