[wwwdocs,arm] Mention new -mcpu and -march extensions

Message ID 5A86ECDE.70803@foss.arm.com
State New
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  • [wwwdocs,arm] Mention new -mcpu and -march extensions
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Commit Message

Kyrill Tkachov Feb. 16, 2018, 2:38 p.m.
Hi all,

This patch adds Richard's march and mcpu option work to changes.html.
It is a helpful extension of the existing functionality and is certainly user-visible
so we want to advertise it.

Checked that it looks ok in Firefox.

Note that the link to the documentation will need to be updated once GCC 8 is released to point to
the GCC 8-specific documentation page rather than the trunk one.

Committing to CVS.



Index: htdocs/gcc-8/changes.html
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-8/changes.html,v
retrieving revision 1.33
diff -U 3 -r1.33 changes.html
--- htdocs/gcc-8/changes.html	26 Jan 2018 04:26:52 -0000	1.33
+++ htdocs/gcc-8/changes.html	16 Feb 2018 13:45:10 -0000
@@ -219,6 +219,24 @@ 
     <code>--with-fpu</code> option.
+    The <code>-march</code> and <code>-mcpu</code> options now accept optional
+    extensions to the architecture or CPU option, allowing the user to enable
+    or disable any such extensions supported by that architecture or CPU
+    such as (but not limited to) floating-point and AdvancedSIMD.
+    For example: the option
+    <code>-mcpu=cortex-a53+nofp</code> will generate code for the Cortex-A53
+    processor with no floating-point support.
+    This, in combination with the new <code>-mfpu=auto</code> option,
+    provides a straightforward way of specifying a valid build target through
+    a single <code>-mcpu</code> or <code>-march</code> option.
+    The <code>-mtune</code> option accepts the same arguments as
+    <code>-mcpu</code> but only the CPU name has an effect on tuning.
+    The architecture extensions do not have any effect.
+    For details of what extensions a particular architecture or CPU option
+    supports please refer to the
+    <a href="https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html#ARM-Options">documentation</a>.
+  </li>
+  <li>
     The <code>-mstructure-size-boundary</code> option has been deprecated and will be
     removed in a future release.