update documentation

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daan 2020-04-20 12:00:39 -07:00
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commit bb6afb7efd
25 changed files with 106 additions and 97 deletions

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<td id="projectlogo"><img alt="Logo" src="mimalloc-logo.svg"/></td>
<td id="projectalign" style="padding-left: 0.5em;">
<div id="projectname">mi-malloc
&#160;<span id="projectnumber">1.4</span>
&#160;<span id="projectnumber">1.6</span>
</div>
</td>
<td> <div id="MSearchBox" class="MSearchBoxInactive">
@ -116,12 +116,13 @@ $(document).ready(function(){initNavTree('overrides.html','');});
<li><code>env DYLD_FORCE_FLAT_NAMESPACE=1 DYLD_INSERT_LIBRARIES=/usr/lib/libmimalloc.dylib myprogram</code></li>
</ul>
<p>Note that certain security restrictions may apply when doing this from the <a href="https://stackoverflow.com/questions/43941322/dyld-insert-libraries-ignored-when-calling-application-through-bash">shell</a>.</p>
<p>Note: unfortunately, at this time, dynamic overriding on macOS seems broken but it is actively worked on to fix this (see issue <a href="https://github.com/microsoft/mimalloc/issues/50"><code>#50</code></a>).</p>
<p>(Note: macOS support for dynamic overriding is recent, please report any issues.)</p>
<h3>Windows</h3>
<p>Overriding on Windows is robust but requires that you link your program explicitly with the mimalloc DLL and use the C-runtime library as a DLL (using the <code>/MD</code> or <code>/MDd</code> switch). Moreover, you need to ensure the <code>mimalloc-redirect.dll</code> (or <code>mimalloc-redirect32.dll</code>) is available in the same folder as the main <code>mimalloc-override.dll</code> at runtime (as it is a dependency). The redirection DLL ensures that all calls to the C runtime malloc API get redirected to mimalloc (in <code>mimalloc-override.dll</code>).</p>
<p>To ensure the mimalloc DLL is loaded at run-time it is easiest to insert some call to the mimalloc API in the <code>main</code> function, like <code>mi_version()</code> (or use the <code>/INCLUDE:mi_version</code> switch on the linker). See the <code>mimalloc-override-test</code> project for an example on how to use this. For best performance on Windows with C++, it is highly recommended to also override the <code>new</code>/<code>delete</code> operations (by including <a href="https://github.com/microsoft/mimalloc/blob/master/include/mimalloc-new-delete.h"><code>mimalloc-new-delete.h</code></a> a single(!) source file in your project).</p>
<p>Overriding on Windows is robust and has the particular advantage to be able to redirect all malloc/free calls that go through the (dynamic) C runtime allocator, including those from other DLL's or libraries.</p>
<p>The overriding on Windows requires that you link your program explicitly with the mimalloc DLL and use the C-runtime library as a DLL (using the <code>/MD</code> or <code>/MDd</code> switch). Also, the <code>mimalloc-redirect.dll</code> (or <code>mimalloc-redirect32.dll</code>) must be available in the same folder as the main <code>mimalloc-override.dll</code> at runtime (as it is a dependency). The redirection DLL ensures that all calls to the C runtime malloc API get redirected to mimalloc (in <code>mimalloc-override.dll</code>).</p>
<p>To ensure the mimalloc DLL is loaded at run-time it is easiest to insert some call to the mimalloc API in the <code>main</code> function, like <code>mi_version()</code> (or use the <code>/INCLUDE:mi_version</code> switch on the linker). See the <code>mimalloc-override-test</code> project for an example on how to use this. For best performance on Windows with C++, it is also recommended to also override the <code>new</code>/<code>delete</code> operations (by including <a href="https://github.com/microsoft/mimalloc/blob/master/include/mimalloc-new-delete.h"><code>mimalloc-new-delete.h</code></a> a single(!) source file in your project).</p>
<p>The environment variable <code>MIMALLOC_DISABLE_REDIRECT=1</code> can be used to disable dynamic overriding at run-time. Use <code>MIMALLOC_VERBOSE=1</code> to check if mimalloc was successfully redirected.</p>
<p>(Note: in principle, it is possible to patch existing executables that are linked with the dynamic C runtime (<code>ucrtbase.dll</code>) by just putting the <code>mimalloc-override.dll</code> into the import table (and putting <code>mimalloc-redirect.dll</code> in the same folder) Such patching can be done for example with <a href="https://ntcore.com/?page_id=388">CFF Explorer</a>).</p>
<p>(Note: in principle, it is possible to even patch existing executables without any recompilation if they are linked with the dynamic C runtime (<code>ucrtbase.dll</code>) &ndash; just put the <code>mimalloc-override.dll</code> into the import table (and put <code>mimalloc-redirect.dll</code> in the same folder) Such patching can be done for example with <a href="https://ntcore.com/?page_id=388">CFF Explorer</a>).</p>
<h2>Static override</h2>
<p>On Unix systems, you can also statically link with <em>mimalloc</em> to override the standard malloc interface. The recommended way is to link the final program with the <em>mimalloc</em> single object file (<code>mimalloc-override.o</code>). We use an object file instead of a library file as linkers give preference to that over archives to resolve symbols. To ensure that the standard malloc interface resolves to the <em>mimalloc</em> library, link it as the first object file. For example:</p>
<div class="fragment"><div class="line">gcc -o myprogram mimalloc-<span class="keyword">override</span>.o myfile1.c ...</div></div><!-- fragment --><h2>List of Overrides:</h2>