Add a paragraph on prefix data layout.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191219 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/LangRef.rst b/docs/LangRef.rst
index 08874bf..4165a5b 100644
--- a/docs/LangRef.rst
+++ b/docs/LangRef.rst
@@ -780,6 +780,11 @@
definition without needing to reason about the prefix data. Obviously this
makes the format of the prefix data highly target dependent.
+Prefix data is laid out as if it were an initializer for a global variable
+of the prefix data's type. No padding is automatically placed between the
+prefix data and the function body. If padding is required, it must be part
+of the prefix data.
+
A trivial example of valid prefix data for the x86 architecture is ``i8 144``,
which encodes the ``nop`` instruction: