[gcc(refs/users/marxin/heads/sphinx-v2)] Update .rst files.

[gcc(refs/users/marxin/heads/sphinx-v2)] Update .rst files.

[Martin Liska]

https://gcc.gnu.org/g:5f3b654ab00ef6d519e6fd27e2daebf05719e0ef

commit 5f3b654ab00ef6d519e6fd27e2daebf05719e0ef
Author: Martin Liska <mliska@suse.cz>
Date:   Fri Jun 25 10:56:27 2021 +0200

    Update .rst files.

Diff:
---
 .../link-time-optimization/design-overview.rst     | 27 +++++++++++-----------
 .../standard-pattern-names-for-generation.rst      | 11 ++++++++-
 2 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/gcc/doc/gccint/link-time-optimization/design-overview.rst b/gcc/doc/gccint/link-time-optimization/design-overview.rst
index e99342b77fe..b58c29d2f0b 100644
--- a/gcc/doc/gccint/link-time-optimization/design-overview.rst
+++ b/gcc/doc/gccint/link-time-optimization/design-overview.rst
@@ -13,11 +13,18 @@ bytecode representation of GIMPLE that is emitted in special sections
 of ``.o`` files.  Currently, LTO support is enabled in most
 ELF-based systems, as well as darwin, cygwin and mingw systems.
 
-Since GIMPLE bytecode is saved alongside final object code, object
-files generated with LTO support are larger than regular object files.
-This 'fat' object format makes it easy to integrate LTO into
-existing build systems, as one can, for instance, produce archives of
-the files.  Additionally, one might be able to ship one set of fat
+By default, object files generated with LTO support contain only GIMPLE
+bytecode.  Such objects are called 'slim', and they require that
+tools like ``ar`` and ``nm`` understand symbol tables of LTO
+sections.  For most targets these tools have been extended to use the
+plugin infrastructure, so GCC can support 'slim' objects consisting
+of the intermediate code alone.
+
+GIMPLE bytecode could also be saved alongside final object code if
+the :option:`-ffat-lto-objects` option is passed, or if no plugin support
+is detected for ``ar`` and ``nm`` when GCC is configured.  It makes
+the object files generated with LTO support larger than regular object
+files.  This 'fat' object format allows to ship one set of fat
 objects which could be used both for development and the production of
 optimized builds.  A, perhaps surprising, side effect of this feature
 is that any mistake in the toolchain leads to LTO information not
@@ -26,14 +33,6 @@ This is both an advantage, as the system is more robust, and a
 disadvantage, as the user is not informed that the optimization has
 been disabled.
 
-The current implementation only produces 'fat' objects, effectively
-doubling compilation time and increasing file sizes up to 5x the
-original size.  This hides the problem that some tools, such as
-``ar`` and ``nm``, need to understand symbol tables of LTO
-sections.  These tools were extended to use the plugin infrastructure,
-and with these problems solved, GCC will also support 'slim' objects
-consisting of the intermediate code alone.
-
 At the highest level, LTO splits the compiler in two.  The first half
 (the 'writer') produces a streaming representation of all the
 internal data structures needed to optimize and generate code.  This
@@ -121,4 +120,4 @@ minimize the number of references which cross partition boundaries.
 The main advantage of WHOPR is to allow the parallel execution of
 LTRANS stages, which are the most time-consuming part of the
 compilation process.  Additionally, it avoids the need to load the
-whole program into memory.
\ No newline at end of file
+whole program into memory.
diff --git a/gcc/doc/gccint/machine-descriptions/standard-pattern-names-for-generation.rst b/gcc/doc/gccint/machine-descriptions/standard-pattern-names-for-generation.rst
index e5fa88ad633..73f202935c1 100644
--- a/gcc/doc/gccint/machine-descriptions/standard-pattern-names-for-generation.rst
+++ b/gcc/doc/gccint/machine-descriptions/standard-pattern-names-for-generation.rst
@@ -1080,6 +1080,15 @@ vec_pack_sbool_trunc_m
   1 and widen the resulting elements. Put the N/2 results of size 2\*S in the
   output vector (operand 0).
 
+  .. index:: vec_addsubm3 instruction pattern
+
+vec_addsubm3
+  Alternating subtract, add with even lanes doing subtract and odd
+  lanes doing addition.  Operands 1 and 2 and the outout operand are vectors
+  with mode :samp:`{m}`.
+
+  These instructions are not allowed to ``FAIL``.
+
   .. index:: mulhisi3 instruction pattern
 
 mulhisi3
@@ -3511,4 +3520,4 @@ clear_cache
 .. Each of the following nodes are wrapped in separate
    "@ifset INTERNALS" to work around memory limits for the default
    configuration in older tetex distributions.  Known to not work:
-   tetex-1.0.7, known to work: tetex-2.0.2.
\ No newline at end of file
+   tetex-1.0.7, known to work: tetex-2.0.2.