r289455 - Bring back note about not supporting global register variables.

[Michael Kuperstein via cfe-commits]

Author: mkuper
Date: Mon Dec 12 13:11:39 2016
New Revision: 289455

URL: http://llvm.org/viewvc/llvm-project?rev=289455&view=rev
Log:
Bring back note about not supporting global register variables.

This was accidentally removed in r260506, even though we only support
non-allocatable global register variables. The general (allocatable) case
is explicitly not supported.

Differential Revision: https://reviews.llvm.org/D27473

Modified:
    cfe/trunk/docs/UsersManual.rst

Modified: cfe/trunk/docs/UsersManual.rst
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/docs/UsersManual.rst?rev=289455&r1=289454&r2=289455&view=diff
==============================================================================
--- cfe/trunk/docs/UsersManual.rst (original)
+++ cfe/trunk/docs/UsersManual.rst Mon Dec 12 13:11:39 2016
@@ -1830,6 +1830,10 @@ extensions are not implemented yet:
      ...
      local_function(1);
 
+-  clang only supports global register variables when the register specified
+   is non-allocatable (e.g. the stack pointer). Support for general global
+   register variables is unlikely to be implemented soon because it requires
+   additional LLVM backend support.
 -  clang does not support static initialization of flexible array
    members. This appears to be a rarely used extension, but could be
    implemented pending user demand.