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Implement C23's free_sized and free_aligned_sized

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[N2699 - Sized Memory Deallocation](https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2699.htm)
introduced two new functions which were incorporated into the C23
standard, `free_sized` and `free_aligned_sized`. Both already have
analogues in Jemalloc, all we are doing here is adding the appropriate
wrappers.
This commit is contained in:
Kevin Svetlitski
2023-07-14 13:14:06 -07:00
committed by Qi Wang
parent 41e0b857be
commit cdb2c0e02f
5 changed files with 75 additions and 1 deletions
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42
doc/jemalloc.xml.in
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@@ -33,6 +33,8 @@
<refname>aligned_alloc</refname>
<refname>realloc</refname>
<refname>free</refname>
<refname>free_sized</refname>
<refname>free_aligned_sized</refname>
<refname>mallocx</refname>
<refname>rallocx</refname>
<refname>xallocx</refname>
@@ -89,6 +91,17 @@
<funcdef>void <function>free</function></funcdef>
<paramdef>void *<parameter>ptr</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>free_sized</function></funcdef>
<paramdef>void *<parameter>ptr</parameter></paramdef>
<paramdef>size_t <parameter>size</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>free_aligned_sized</function></funcdef>
<paramdef>void *<parameter>ptr</parameter></paramdef>
<paramdef>size_t <parameter>alignment</parameter></paramdef>
<paramdef>size_t <parameter>size</parameter></paramdef>
</funcprototype>
</refsect2>
<refsect2>
<title>Non-standard API</title>
@@ -227,6 +240,17 @@
allocated memory referenced by <parameter>ptr</parameter> to be made
available for future allocations. If <parameter>ptr</parameter> is
<constant>NULL</constant>, no action occurs.</para>
<para>The <function>free_sized()</function> function is an extension of
<function>free()</function> with a <parameter>size</parameter> parameter
to allow the caller to pass in the allocation size as an optimization.
</para>
<para>The <function>free_aligned_sized()</function> function accepts a
<parameter>ptr</parameter> which was allocated with a requested
<parameter>size</parameter> and <parameter>alignment</parameter>, causing
the allocated memory referenced by <parameter>ptr</parameter> to be made
available for future allocations.</para>
</refsect2>
<refsect2>
<title>Non-standard API</title>
@@ -451,6 +475,24 @@ for (i = 0; i < nbins; i++) {
depended on, since such behavior is entirely implementation-dependent.
</para>
</refsect2>
<refsect2>
<title>Interactions Between the Standard and Non-standard APIs</title>
<para>Generally speaking it is permissible to pass pointers obtained from
the standard API to the non-standard API and vice versa (e.g. calling
<function>free()</function> with a pointer returned by a call to
<function>mallocx()</function>, calling <function>sdallocx()</function>
with a pointer returned by a call to <function>calloc()</function>).
There are however a few exceptions. In keeping with the C23 standard –
which forbids calling <function>free_sized()</function> on a pointer
returned by <function>aligned_alloc()</function>, mandating that either
<function>free_aligned_sized()</function> or <function>free()</function>
be used instead – using any combination of the standard and non-standard
APIs in an equivalent fashion (i.e. taking a pointer which was allocated
with an explicitly requested alignment and attempting to free it via an
API that accepts a size hint, without also providing the alignment hint)
is likewise forbidden.
</para>
</refsect2>
</refsect1>
<refsect1 id="tuning">
<title>TUNING</title>