[PATCH v4 5/5] Add documentation for musttail attribute

[Andi Kleen <ak@linux.intel.com>]

gcc/ChangeLog:

	* doc/extend.texi: Document [[musttail]]
---
 gcc/doc/extend.texi | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 142e41ab8fbf..866f6c4a9fed 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -9875,6 +9875,22 @@ foo (int x, int y)
 @code{y} is not actually incremented and the compiler can but does not
 have to optimize it to just @code{return 42 + 42;}.
 
+@cindex @code{musttail} statement attribute
+@item musttail
+
+The @code{gnu::musttail} or @code{clang::musttail} attribute
+can be applied to a return statement that returns the value
+of a call to indicate that the call must be a tail call
+that does not allocate extra stack space.
+
+@smallexample
+[[gnu::musttail]] return foo();
+@end smallexample
+
+If the compiler cannot generate a tail call it will generate
+an error. Tail calls generally require enabling optimization.
+On some targets they may not be supported.
+
 @end table
 
 @node Attribute Syntax
-- 
2.43.0