[llvm] r322786 - [LangRef] Clarify Varargs forwarding for musttail calls.

[Florian Hahn via llvm-commits]

Author: fhahn
Date: Wed Jan 17 15:29:25 2018
New Revision: 322786

URL: http://llvm.org/viewvc/llvm-project?rev=322786&view=rev
Log:
[LangRef] Clarify Varargs forwarding for musttail calls.

This clarification was suggested by @efriedma in D41335, which uses this
behavior to inline musttail calls with varargs.

Reviewers: hfinkel, efriedma, rnk

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D41861

Modified:
    llvm/trunk/docs/LangRef.rst

Modified: llvm/trunk/docs/LangRef.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.rst?rev=322786&r1=322785&r2=322786&view=diff
==============================================================================
--- llvm/trunk/docs/LangRef.rst (original)
+++ llvm/trunk/docs/LangRef.rst Wed Jan 17 15:29:25 2018
@@ -9033,9 +9033,11 @@ This instruction requires several argume
    #. Arguments with the :ref:`inalloca <attr_inalloca>` attribute are
       forwarded in place.
 
-   Both markers imply that the callee does not access allocas or varargs from
-   the caller. Calls marked ``musttail`` must obey the following additional
-   rules:
+   Both markers imply that the callee does not access allocas from the caller.
+   The ``tail`` marker additionally implies that the callee does not access
+   varargs from the caller, while ``musttail`` implies that varargs from the
+   caller are passed to the callee. Calls marked ``musttail`` must obey the
+   following additional  rules:
 
    - The call must immediately precede a :ref:`ret <i_ret>` instruction,
      or a pointer bitcast followed by a ret instruction.