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[wwwdocs] add gcc 9 changes
- From: Martin Sebor <msebor at gmail dot com>
- To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 4 Mar 2019 17:28:26 -0700
- Subject: [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
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>