Clarify that GlobalVariables definitions must have an initializer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193609 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/LangRef.rst b/docs/LangRef.rst
index 6bf141e..965858c 100644
--- a/docs/LangRef.rst
+++ b/docs/LangRef.rst
@@ -445,9 +445,13 @@
----------------
Global variables define regions of memory allocated at compilation time
-instead of run-time. Global variables may optionally be initialized, may
-have an explicit section to be placed in, and may have an optional
-explicit alignment specified.
+instead of run-time.
+
+Global variables definitions must be initialized, may have an explicit section
+to be placed in, and may have an optional explicit alignment specified.
+
+Global variables in other translation units can also be declared, in which
+case they don't have an initializer.
A variable may be defined as ``thread_local``, which means that it will
not be shared by threads (each thread will have a separated copy of the
@@ -529,6 +533,12 @@
@G = addrspace(5) constant float 1.0, section "foo", align 4
+The following example just declares a global variable
+
+.. code-block:: llvm
+
+ @G = external global i32
+
The following example defines a thread-local global with the
``initialexec`` TLS model: