doc: update gccgo_contribute.html

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5673080

doc/gccgo_contribute.html

@@ -5,90 +5,95 @@
 <h2>Introduction</h2>
 
 <p>
-These are some notes on contributing to the <code>gccgo</code>
-frontend for GCC.  For information on contributing to parts of Go other
-than <code>gccgo</code>, see <a href="contribute.html">Contributing to
-the Go project</a>.  For information on building <code>gccgo</code>
-for yourself, see <a href="gccgo_install.html">Setting up and using
-gccgo</a>.
+These are some notes on contributing to the gccgo frontend for GCC.
+For information on contributing to parts of Go other than gccgo,
+see <a href="contribute.html">Contributing to the Go project</a>.  For
+information on building gccgo for yourself,
+see <a href="gccgo_install.html">Setting up and using gccgo</a>.
 </p>
 
 <h2>Legal Prerequisites</h2>
 
 <p>
 You must follow the <a href="contribute.html#copyright">Go copyright
-rules.</a>
+rules</a> for all changes to the gccgo frontend and the associated
+libgo library.  Code that is part of GCC rather than gccgo must follow
+the general <a href="http://gcc.gnu.org/contribute.html">GCC
+contribution rules</a>.
 </p>
 
 <h2>Code</h2>
 
 <p>
-The source code for the <code>gccgo</code> frontend may be found at
+The master sources for the gccgo frontend may be found at
 <a href="http://code.google.com/p/gofrontend">http://code.google.com/p/gofrontend</a>.
-Changes made to that project are routinely merged into the source code
-hosted at <code>gcc.gnu.org</code>.  The <code>gofrontend</code>
-project includes only the Go frontend proper.  These are the files
-which in the <code>gcc</code> sources may be found in the
-directories <code>gcc/go</code> and <code>libgo</code>.
-The <code>gcc</code> sources also include a copy of
-the <code>test</code> directory
-from <a href="http://code.google.com/p/go">the main Go repository</a>.
-
-<p>
-The frontend is written in C++ and as such the GNU coding standards do
-not entirely apply; in writing code for the frontend, follow the
-formatting of the surrounding code.  Although the frontend is
-currently closely tied to the rest of the <code>gcc</code> codebase,
-we plan to make it more independent.  Any new code that uses other
-parts of <code>gcc</code> should be placed in an appropriate file,
-such as <code>gogo-tree.cc</code>.  Eventually
-all <code>gcc</code>-specific code should migrate to
-a <code>gcc-interface</code> subdirectory.
+The master sources are not buildable by themselves, but only in
+conjunction with GCC (in the future, other compilers may be
+supported).  Changes made to the gccgo frontend are also applied to
+the GCC source code repository hosted at <code>gcc.gnu.org</code>.  In
+the <code>gofrontend</code> repository, the <code>go</code> directory
+is mirrored to the <code>gcc/go/gofrontend</code> directory in the GCC
+repository, and the <code>gofrontend</code> <code>libgo</code>
+directory is mirrored to the GCC <code>libgo</code> directory.  In
+addition, the <code>test</code> directory
+from <a href="http://code.google.com/p/go">the main Go repository</a>
+is mirrored to the <code>gcc/testsuite/go.test/test</code> directory
+in the GCC repository.
 </p>
 
 <p>
-The run-time library for <code>gccgo</code> is mostly the same as the
-library in <a href="http://code.google.com/p/go">the main Go
-repository</a>.  The library code in the Go repository is periodically
-copied into the <code>gofrontend</code> and the <code>gcc</code>
-repositories.  Accordingly, most library changes should be made in the
-main Go repository.  Changes to the few <code>gccgo</code>-specific
-parts of the library should follow the process described here.
-The <code>gccgo</code>-specific parts of the library are everything in
-the <code>libgo</code> directory except for the <code>libgo/go</code>
-subdirectory.
+Changes to these directories always flow from the master sources to
+the GCC repository.  The files should never be changed in the GCC
+repository except by changing them in the master sources and mirroring
+them.
+</p>
+
+<p>
+The gccgo frontend is written in C++.  It follows the GNU coding
+standards to the extent that they apply to C++.  In writing code for
+the frontend, follow the formatting of the surrounding code.  Although
+the frontend is currently tied to the rest of the GCC codebase, we
+plan to make it more independent.  Eventually all GCC-specific code
+will migrate out of the frontend proper and into GCC proper.  In the
+GCC sources this will generally mean moving code
+from <code>gcc/go/gofrontend</code> to <code>gcc/go</code>.
+</p>
+
+<p>
+The run-time library for gccgo is mostly the same as the library
+in <a href="http://code.google.com/p/go">the main Go repository</a>.
+The library code in the Go repository is periodically merged into
+the <code>libgo/go</code> directory of the <code>gofrontend</code> and
+then the GCC repositories, using the shell
+script <code>libgo/merge.sh</code>.  Accordingly, most library changes
+should be made in the main Go repository.  The files outside
+of <code>libgo/go</code> are gccgo-specific; that said, some of the
+files in <code>libgo/runtime</code> are based on files
+in <code>src/pkg/runtime</code> in the main Go repository.
 </p>
 
 <h2>Testing</h2>
 
 <p>
-All patches must be tested.  There are two test suites.  A patch that
-introduces new failures is not acceptable.
+All patches must be tested.  A patch that introduces new failures is
+not acceptable.
 </p>
 
 <p>
-To run the compiler test suite, run <code>make check-go</code> in the
-<code>gcc</code> subdirectory of your build directory.  This will run
-various tests underneath <code>gcc/testsuite/go.*</code>.  This
-includes a copy of the tests in the main Go repository, which are run
-using the DejaGNU script found in
-in <code>gcc/testsuite/go.test/go-test.exp</code>.  Many of the
-compiler tests may be run without the Go library, but some do require
-the library to built first.
+To run the gccgo test suite, run <code>make check-go</code> in your
+build directory.  This will run various tests
+under <code>gcc/testsuite/go.*</code> and will also run
+the <code>libgo</code> testsuite.  This copy of the tests from the
+main Go repository is run using the DejaGNU script found in
+in <code>gcc/testsuite/go.test/go-test.exp</code>.
 </p>
 
 <p>
-To run the library test suite, run <code>make
-check-target-libgo</code> in the top level of your build directory.
-</p>
-
-<p>
-Most new tests should be submitted to the main Go repository for
-copying into the <code>gccgo</code> repository.  If there is a need
-for specific tests for <code>gccgo</code>, they should go in
+Most new tests should be submitted to the main Go repository for later
+mirroring into the GCC repository.  If there is a need for specific
+tests for gccgo, they should go in
 the <code>gcc/testsuite/go.go-torture</code>
-or <code>gcc/testsuite/go.dg</code> directories in
-the <code>gcc.gnu.org</code> repository.
+or <code>gcc/testsuite/go.dg</code> directories in the GCC repository.
 </p>
 
 <h2>Submitting Changes</h2>
@@ -97,5 +102,5 @@ the <code>gcc.gnu.org</code> repository.
 Changes to the Go frontend should follow the same process as for the
 main Go repository, only for the <code>gofrontend</code> project
 rather than the <code>go</code> project.  Those changes will then be
-merged into the <code>gcc</code> sources.
+merged into the GCC sources.
 </p>