[wwwdocs] Add GCC10 IPA/LTO changes

[Jan Hubicka]

Hi,
here are some of changes of LTO/IPA done in GCC10.  There is also
recursive cloning and some other stuff I will add incrementally as well
as some data on overall compile time/memory use improvements as we
reported in past years. I am still running tests and fixing bugs in this
area.

Honza

diff --git a/htdocs/gcc-10/changes.html b/htdocs/gcc-10/changes.html
index aca76825..0f0fce18 100644
--- a/htdocs/gcc-10/changes.html
+++ b/htdocs/gcc-10/changes.html
@@ -50,12 +50,46 @@ a work-in-progress.</p>
 <!-- .................................................................. -->
 <h2 id="general">General Improvements</h2>
 
+<p>The following GCC command line options have been introduced or improved.</p>
+<ul>
+  <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Optimize-Options.html#index-fprofile-partial-training"><code>-fprofile-partial-training</code></a>
+      can now be used to inform compiler that code paths not covered by the
+      train run should not be optimized for size.</li>
+</ul>
 <p>The following built-in functions have been introduced.</p>
 <ul>
   <li><code>__builtin_roundeven</code> for the corresponding function from
     ISO/IEC TS 18661.
   </li>
 </ul>
+<p>A large number of improvements to code generation have been made, including
+   but not limited to the following.</p>
+<ul>
+  <li>Inter-procedural optimization improvements:
+   <ul>
+    <li>Inter-procedural scalar replacement for aggregates (IPA-SRA) pass was re-implemented to work at link-time.
+    </li>
+    <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Optimize-Options.html#index-finline-functions"><code>-finline-functions</code></a>
+	is now enabled at <code>-O2</code> and was retuned for better code size
+	versus runtime performance tradeofs.  Inliner heuristics was also
+	significantly sped up to avoid negativive impact to <code>-flto
+	-O2</code> compile times.
+    </li>
+    <li>Inliner heuristics and function clonning can now use value-range
+        information to predict effectivity of individual transformations.</li>
+    <li>Selected <code>--param</code> values can now be specified at
+        translation unit granuality. This includes all parameters controlling
+        inliner.</li>
+    <li>During link-time optimization the C++ One Definition Rule is used to
+        increase precision of type based alias analysis.</li>
+   </ul>
+  </li>
+  <li>Profile driven optimization improvements:
+   <ul>
+    <li>Profile maintenance during compilation was improved and hot/cold code partitioning improved.</li>
+   </ul>
+  </li>
+</ul>
 
 <!-- .................................................................. -->
 <h2 id="languages">New Languages and Language specific improvements</h2>