[wwwdocs] add gcc 9 changes

Attached is a patch with (mostly) my changes for GCC 9.  To make
things easier to find I grouped related changes together within
the sections I changed.  I put warnings under the same bullet,
built-ins, and attributes.

Martin

Ping: https://gcc.gnu.org/ml/gcc-patches/2019-03/msg00147.html

On 3/4/19 5:28 PM, Martin Sebor wrote:
> Attached is a patch with (mostly) my changes for GCC 9.  To make
> things easier to find I grouped related changes together within
> the sections I changed.  I put warnings under the same bullet,
> built-ins, and attributes.
> 
> Martin

On 3/4/19 5:28 PM, Martin Sebor wrote:
> Attached is a patch with (mostly) my changes for GCC 9.  To make
> things easier to find I grouped related changes together within
> the sections I changed.  I put warnings under the same bullet,
> built-ins, and attributes.

I have a few nit-picky comments...

s/command line option/command-line option/g
s/command line utilitly/command-line utility/  (typo, not just hyphen)
s/red-zones/red zones/g

Please try to reformat this to avoid lines longer than 80 characters, 
except where it's unavoidable in <a href="..."> markup.

-Sandra

On 3/17/19 11:24 AM, Sandra Loosemore wrote:
> On 3/4/19 5:28 PM, Martin Sebor wrote:
>> Attached is a patch with (mostly) my changes for GCC 9.  To make
>> things easier to find I grouped related changes together within
>> the sections I changed.  I put warnings under the same bullet,
>> built-ins, and attributes.
> 
> I have a few nit-picky comments...
> 
> s/command line option/command-line option/g
> s/command line utilitly/command-line utility/  (typo, not just hyphen)
> s/red-zones/red zones/g

Fixed.

> 
> Please try to reformat this to avoid lines longer than 80 characters, 
> except where it's unavoidable in <a href="..."> markup.

I spotted just a couple of lines in the diff that were exactly
80 characters long but I'm not sure where else this could be
done.  AFAICS, all the long lines I added are because of
the <a href="..."> tags.

There are a few lines in the file that the patch doesn't touch
that are a few characters over 80.  Because of the <a href...>
tags and the overall lack of consistency in indentation (two vs
four spaces) I don't think it matters enough here to spend time
changing.

Martin

PS We could fit most lines into 80 characters by introducing some
macro for all the <a href="gcc-option.html> tags.  That would make
it easier to insert these links too.  E.g.,
<option>-falign-functions</option> could be expanded by some
post-processing script into

<a 
href="https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Optimize-Options.html#index-falign-functions"><code>-falign-functions</code></a>

That way the option links would also continue to work even if
in some later release the options were removed or renamed.  (In
GCC 8 I made the links point at the gcc-8.1.0 docs but I haven't
done it here.)  I don't know enough about how these files are
processed to do this.
Index: gcc-9/changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-9/changes.html,v
retrieving revision 1.49
diff -u -r1.49 changes.html
--- gcc-9/changes.html	28 Feb 2019 21:49:05 -0000	1.49
+++ gcc-9/changes.html	5 Mar 2019 00:18:18 -0000
@@ -60,8 +60,17 @@
 
 <!-- .................................................................. -->
 <h2 id="general">General Improvements</h2>
+<p>The following GCC command line options have been introduced or improved.</p>
 <ul>
   <li>
+    All command line options that take a <i>byte-size</i> argument accept
+    64-bit integers as well as standard SI and IEC suffixes such as
+    <code>kb</code> and <code>KiB</code>, <code>MB</code> and <code>MiB</code>,
+    or <code>GB</code> and <code>GiB</code> denoting the corresponding
+    multiples of bytes.  See
+    <a href="https://gcc.gnu.org/onlinedocs/gcc/Invoking-GCC.html#Invoking-GCC">Invoking GCC</a> for more.
+  </li>
+  <li>
     A new option, <a href="https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-flive-patching"><code>-flive-patching=[inline-only-static|inline-clone]</code></a>, has been
     introduced to provide a safe compilation for live-patching. At the same
     time, provides multiple-level control on the enabled IPA optimizations.
@@ -79,9 +88,41 @@
       alignment (e.g. <code>-falign-loops=n:m:n2:m2</code>).
   </li>
   <li>
-      A new built-in function, <a href="https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005fexpect_005fwith_005fprobability"><code>__builtin_expect_with_probability</code></a>,
-      has been added.
+      New pair of profiling options (<a href="https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#index-fprofile-filter-files"><code>-fprofile-filter-files</code></a>
+      and <a href="https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#index-fprofile-exclude-files"><code>-fprofile-exclude-files</code></a>) has been added.
+      The options help to filter which source files are instrumented.
+  </li>
+  <li>
+      AddressSanitizer generates more compact red-zones for automatic variables.
+      That helps to reduce memory footprint of a sanitized binary.
   </li>
+</ul>
+<p>The following built-in functions have been introduced.</p>
+<ul>
+  <li>
+    <a href="https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005fexpect_005fwith_005fprobability"><code>__builtin_expect_with_probability</code></a> to provide branch prediction probability hints to
+    the optimizer.
+  </li>
+  <li>
+    <a href="https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005fhas_005fattribute-1"><code>__builtin_has_attribute</code></a> determines whether a function, type, or variable has been declared with some
+    attribute.
+  </li>
+  <li>
+    <a href="https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005fspeculation_005fsafe_005fvalue-1"><code>__builtin_speculation_safe_value</code></a> can be used to help mitigate against unsafe speculative
+    execution.
+  </li>
+</ul>
+<p>The following attributes have been introduced.</p>
+<ul>
+  <li>
+    The <a href="https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute"><code>copy</code></a> function attribute has been
+    added.  The attribute can also be applied to type definitions and to
+    variable declarations.
+  </li>
+</ul>
+<p>A large number of improvements to code generation have been made,
+  including but not limited to the following.</p>
+<ul>
   <li>
       Switch expansion has been improved by using a different strategy
       (jump table, bit test, decision tree) for a subset of switch cases.
@@ -106,6 +147,10 @@
       can be transformed into <code>100 * how + 5</code> (for values defined
       in the switch statement).
   </li>
+</ul>
+<p>The following improvements to the <tt>gcov</tt> command line utilitly
+  have been made.</p>
+<ul>
   <li>
       The gcov tool received a new option <a href="https://gcc.gnu.org/onlinedocs/gcc/Invoking-Gcov.html#Invoking-Gcov"><code>--use-hotness-colors</code></a>
       (<code>-q</code>) that can provide perf-like coloring of hot functions.
@@ -113,15 +158,6 @@
   <li>
       The gcov tool has changed its intermediate format to a new JSON format.
   </li>
-  <li>
-      New pair of profiling options (<a href="https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#index-fprofile-filter-files"><code>-fprofile-filter-files</code></a>
-      and <a href="https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#index-fprofile-exclude-files"><code>-fprofile-exclude-files</code></a>) has been added.
-      The options help to filter which source files are instrumented.
-  </li>
-  <li>
-      AddressSanitizer generates more compact red-zones for automatic variables.
-      That helps to reduce memory footprint of a sanitized binary.
-  </li>
 </ul>
 
 <!-- .................................................................. -->
@@ -139,7 +175,6 @@
       not supported in the GCC 9 release see
       <a href="https://gcc.gnu.org/ml/gcc-patches/2018-11/msg00628.html">this mail</a>.
   </li>
-
   <li>New extensions:
   <ul>
     <li><a href="https://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#index-_005f_005fbuiltin_005fconvertvector"><code>__builtin_convertvector</code></a> built-in for vector conversions
@@ -152,7 +187,40 @@
       warns about an unaligned pointer value from the address of a packed
       member of a struct or union.
       </li>
-  </ul></li>
+  </ul>
+
+  <li>Enhancements to existing warnings:
+    <ul>
+      <li>
+	<a href="https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Warray-bounds"><code>-Warray-bounds</code></a> detects more instances
+	of out-of-bounds indices.
+      </li>
+      <li>
+	<a href="https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wattribute-alias"><code>-Wattribute-alias</code></a> also detects attribute
+	mismatches between alias declarations and their targets, in addition
+	to mismatches between their types.
+      </li>
+      <li>
+	<a href="https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wformat-overflow"><code>-Wformat-overflow</code></a> and
+	<a href="https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wformat-truncation"><code>-Wformat-truncation</code></a> have been extended
+	to all formatted input/output functions (where applicable) and
+	enhanced to detect a subset of instances of reading past the end
+	of unterminated constant character arrays in <code>%s</code>
+	directives.
+      </li>
+      <li>
+	<a href="https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wmissing-attributes"><code>-Wmissing-attributes</code></a> detects instances
+	of missing function attributes on declarations of aliases and weak
+	references.
+      </li>
+      <li>
+	<a href="https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wstringop-truncation"><code>-Wstringop-truncation</code></a> also detects
+	a subset of instances of reading past the end of unterminated
+	constant character arrays,
+      </li>
+    </ul>
+  </li>
+  
 </ul>
 
 <h3 id="c">C</h3>

On 3/18/19 10:59 AM, Martin Sebor wrote:
> On 3/17/19 11:24 AM, Sandra Loosemore wrote:
>> On 3/4/19 5:28 PM, Martin Sebor wrote:
>>> Attached is a patch with (mostly) my changes for GCC 9.  To make
>>> things easier to find I grouped related changes together within
>>> the sections I changed.  I put warnings under the same bullet,
>>> built-ins, and attributes.
>>
>> I have a few nit-picky comments...
>>
>> s/command line option/command-line option/g
>> s/command line utilitly/command-line utility/  (typo, not just hyphen)
>> s/red-zones/red zones/g
> 
> Fixed.
> 
>>
>> Please try to reformat this to avoid lines longer than 80 characters,
>> except where it's unavoidable in <a href="..."> markup.
> 
> I spotted just a couple of lines in the diff that were exactly
> 80 characters long but I'm not sure where else this could be
> done.  AFAICS, all the long lines I added are because of
> the <a href="..."> tags.
> 
> There are a few lines in the file that the patch doesn't touch
> that are a few characters over 80.  Because of the <a href...>
> tags and the overall lack of consistency in indentation (two vs
> four spaces) I don't think it matters enough here to spend time
> changing.
> 
> Martin
> 
> PS We could fit most lines into 80 characters by introducing some
> macro for all the <a href="gcc-option.html> tags.  That would make
> it easier to insert these links too.  E.g.,
> <option>-falign-functions</option> could be expanded by some
> post-processing script into
> 
> <a
> href="https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Optimize-Options.html#index-falign-functions"><code>-falign-functions</code></a>
> 
> 
> That way the option links would also continue to work even if
> in some later release the options were removed or renamed.  (In
> GCC 8 I made the links point at the gcc-8.1.0 docs but I haven't
> done it here.)  I don't know enough about how these files are
> processed to do this.
> 
> gcc-9-changes.diff
OK
jeff