Gerald, Andi,
thanks for corrections. This is what I've comitted now.
Index: changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-4.7/changes.html,v
retrieving revision 1.33
diff -u -r1.33 changes.html
--- changes.html 25 Sep 2011 22:49:42 -0000 1.33
+++ changes.html 27 Sep 2011 13:50:13 -0000
@@ -58,6 +58,68 @@
was added to allow users to control the cutoff between doing switch
statements
as a series of if statements and using a jump table.
</li>
+ <li>Link-time optimization improvements:
+ <ul>
+ <li>Improved scalability and reduced memory usage. Link time
optimization
+ of Firefox now requires 3GB of RAM on a 64bit system, while over 8GB was
needed
+ previously. Linking time has been improved, too. The serial stage of
linking
+ Firefox binary has been sped up approximately by factor of 10.</li>
+ <li>Reduced size of object files and temporary storage used during
linking.</li>
+ <li>Streaming performance (both outbound and inbound) has been
improved.</li>
+ <li><code>ld -r</code> is now supported with LTO.</li>
+ <li>Several bug fixes, especially in symbol table handling and
merging.</li>
+ </ul>
+ <li>Interprocedural optimization improvements:
+ <li>Inliner heuristic can now take into account that after inlining
+ code will be optimized out because of known values (or properties) of
function parameters.
+ For example:
+ <pre>
+void foo(int a)
+{
+ if (a>10)
+ ... huge code ...
+}
+void bar (void)
+{
+ foo (0);
+}
+ </pre>
+ The call of <code>foo</code> will be inlined into <code>bar</code> even
when
+ optimizing for code size. Constructs based on
<code>__builtin_constant_p</code>
+ are now understood by the inliner and code size estimates are evaluated
a lot
+ more realistically.</li>
+ <li>The representation of C++ virtual thunks and aliases (both implicit
and defined
+ via <code>alias</code>attribute) has been re-engineered. The aliases no
+ longer pose optimization barriers and calls to an alias can be inlined
+ and otherwise optimized.</li>
+ <li>The inter-procedural constant propagation pass has been rewritten.
+ It now performs generic function specialization. For example when
+ compiling the following:
+ <pre>
+void foo(bool flag)
+{
+ if (flag)
+ ... do something ...
+ else
+ ... do something else ...
+}
+void bar (void)
+{
+ foo (false);
+ foo (true);
+ foo (false);
+ foo (true);
+ foo (false);
+ foo (true);
+}
+ </pre>
+ GCC will now produce two copies of <code>foo</code>. One with
<code>flag</code> being
+ <code>true</code>, while other with <code>flag</code> being
+ <code>false</code>. This leads to performance improvements previously
+ possibly only by inlining all calls. Cloning causes a lot less code size
+ growth.
+ <ul>
+ </ul>
</ul>
<h2>New Languages and Language specific improvements</h2>
