On Mon, 19 Mar 2018, Jan Hubicka wrote:
> Hi,
> this patch adds some documentation for what is new in IPA and x86.
> For lto we should mention early-debug. Richard, perhaps you can suggest
> wording?
I have committed the following (will happily edit if necessary).
Richard.
2018-03-20 Richard Biener <rguent...@suse.de>
* changes.html: Mention early LTO debug, -floop-nest-optimize
improvements, -floop-unroll-and-jam, -floop-interchange,
-fstack-clash-protection and adjust the -fno-strict-overflow
entry for the new -fwrapv-pointer.
Index: changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-8/changes.html,v
retrieving revision 1.45
diff -u -r1.45 changes.html
--- changes.html 19 Mar 2018 23:53:35 -0000 1.45
+++ changes.html 20 Mar 2018 08:17:45 -0000
@@ -68,6 +68,13 @@
bodies into hot and cold regions, is now enabled by default at
<code>-O2</code>
and higher for x86 and x86-64.</li>
</ul>
+ <li>Link-time optimization improvements:
+ <ul>
+ <li>On ELF targets using DWARF debug information has been significantly
+ improved in quality by properly preserving language-specific
+ debug information. This allows for example the libstdc++
+ pretty-printers to work with LTO optimized executables.</li>
+ </ul>
<li>
A new option <code>-fcf-protection=[full|branch|return|none]</code> is
introduced to perform code instrumentation to increase program security by
@@ -77,6 +84,25 @@
guide for further information about the option syntax and section "New
Targets
and Target Specific Improvements" for IA-32/x86-64 for more details.
</li>
+ <li>
+ The polyhedral-based loop nest optimization pass
+ <code>-floop-nest-optimize</code> has been overhauled. It's still
+ considered experimental and may not result in any runtime improvements.
+ </li>
+ <li>
+ Two new classical loop nest optimization passes have been added.
+ <code>-floop-unroll-and-jam</code> performs outer loop unrolling
+ and fusing of the inner loop copies. <code>-floop-interchange</code>
+ exchanges loops in a loop nest to improve data locality. Both passes
+ are enabled by default at <code>-O3</code> and above.
+ </li>
+ <li>
+ The new option <code>-fstack-clash-protection</code> causes the
+ compiler to insert probes whenever stack space is allocated
+ statically or dynamically to reliably detect stack overflows and
+ thus mitigate the attack vector that relies on jumping over
+ a stack guard page as provided by the operating system.
+ </li>
</ul>
@@ -139,8 +165,8 @@
</ul>
</li>
<li><code>-fno-strict-overflow</code> is now mapped to
- <code>-fwrapv</code> and signed integer overflow is now undefined by
- default at all optimization levels. Using
+ <code>-fwrapv -fwrapv-pointer</code> and signed integer overflow
+ is now undefined by default at all optimization levels. Using
<code>-fsanitize=signed-integer-overflow</code> is now the preferred
way to audit code, <code>-Wstrict-overflow</code> is deprecated.</li>
</ul>
