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Use present tense when talking about User layout. It is implemented now.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52699 91177308-0d34-0410-b5e6-96231b3b80d8
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Gabor Greif 2008-06-25 00:10:22 +00:00
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docs/ProgrammersManual.html
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@ -2265,18 +2265,18 @@ array from the <tt>User</tt> object and there may be a variable
number of them.</p>
</ul>
<p>
Initially each layout will possess a direct pointer to the
As of v2.4 each layout still possesses a direct pointer to the
start of the array of <tt>Use</tt>s. Though not mandatory for layout a),
we stick to this redundancy for the sake of simplicity.
The <tt>User</tt> object will also store the number of <tt>Use</tt> objects it
The <tt>User</tt> object also stores the number of <tt>Use</tt> objects it
has. (Theoretically this information can also be calculated
given the scheme presented below.)</p>
<p>
Special forms of allocation operators (<tt>operator new</tt>)
will enforce the following memory layouts:</p>
enforce the following memory layouts:</p>
<ul>
<li><p>Layout a) will be modelled by prepending the <tt>User</tt> object by the <tt>Use[]</tt> array.</p>
<li><p>Layout a) is modelled by prepending the <tt>User</tt> object by the <tt>Use[]</tt> array.</p>
<pre>
...---.---.---.---.-------...
@ -2284,7 +2284,7 @@ will enforce the following memory layouts:</p>
'''---'---'---'---'-------'''
</pre>
<li><p>Layout b) will be modelled by pointing at the Use[] array.</p>
<li><p>Layout b) is modelled by pointing at the <tt>Use[]</tt> array.</p>
<pre>
.-------...
| User
@ -2306,12 +2306,12 @@ will enforce the following memory layouts:</p>
<div class="doc_text">
<p>
Since the <tt>Use</tt> objects will be deprived of the direct pointer to
Since the <tt>Use</tt> objects are deprived of the direct (back)pointer to
their <tt>User</tt> objects, there must be a fast and exact method to
recover it. This is accomplished by the following scheme:</p>
</div>
A bit-encoding in the 2 LSBits (least significant bits) of the <tt>Use::Prev</tt> will allow to find the
A bit-encoding in the 2 LSBits (least significant bits) of the <tt>Use::Prev</tt> allows to find the
start of the <tt>User</tt> object:
<ul>
<li><tt>00</tt> &mdash;&gt; binary digit 0</li>
@ -2441,9 +2441,9 @@ never change after being set up, setters of <tt>Use::Prev</tt> must re-tag the
new <tt>Use**</tt> on every modification. Accordingly getters must strip the
tag bits.</p>
<p>
For layout b) instead of the <tt>User</tt> we will find a pointer (<tt>User*</tt> with LSBit set).
Following this pointer brings us to the <tt>User</tt>. A portable trick will ensure
that the first bytes of <tt>User</tt> (if interpreted as a pointer) will never have
For layout b) instead of the <tt>User</tt> we find a pointer (<tt>User*</tt> with LSBit set).
Following this pointer brings us to the <tt>User</tt>. A portable trick ensures
that the first bytes of <tt>User</tt> (if interpreted as a pointer) never has
the LSBit set.</p>
</div>