NaCl docs: update computed goto support

native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst

Index: native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
diff --git a/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst b/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
index b147cca150f2bae078811640da8915b85cb6536e..8ae4aaada11d0fd390808b18fe33983316aca9e7 100644
--- a/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
+++ b/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
@@ -225,6 +225,14 @@ mostly IEEE-754 compliant. There are a few caveats:
     currently doesn't, use hardware support if fast-math were provided
     in the *pexe*.
 
+Computed ``goto``
+=================
+
+PNaCl supports computed ``goto``, a non-standard extension to C used by

[Mark Seaborn, 2014/03/03 21:23:04]

You could be more specific and say "GCC extension".

ExpandIndirectBr.cpp has this extra advice that would be useful to put in the
docs:

// The resulting use of switches might not be as fast as the original
// indirectbrs.  If you are compiling a program that has a
// compile-time option for using computed gotos, it's possible that
// the program will run faster with the option turned off than with
// using computed gotos + ExpandIndirectBr (for example, if the
// program does extra work to take advantage of computed gotos).

[JF, 2014/03/03 21:30:32]

That's helpful, I added it. Thanks!

+some interpreters, by lowering them to ``switch`` statements.
+
+NaCl supports computed ``goto``.
+
 Future Directions
 =================
 
@@ -273,11 +281,3 @@ POSIX-style signal handling really consists of two different features:
 If PNaCl were to support either of these, the interaction of
 ``volatile`` and atomics with same-thread signal handling would need
 to be carefully detailed.
-
-Computed ``goto``
------------------
-
-PNaCl currently doesn't support computed ``goto``, a non-standard
-extension to C used by some interpreters.
-
-NaCl supports computed ``goto``.