Add an 'inline hint' attribute to represent source

code hints that it would be a good idea to inline
a function ("inline" keyword).  No functional change
yet; FEs do not emit this and inliner does not use it.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80063 91177308-0d34-0410-b5e6-96231b3b80d8

docs/LangRef.html

@@ -1042,6 +1042,11 @@ define void @f() optsize
       function into callers whenever possible, ignoring any active inlining size
       threshold for this caller.</dd>
 
+  <dt><tt>inlinehint</tt></dt>
+  <dd>This attribute indicates that the source code contained a hint that inlining
+      this function is desirable (such as the "inline" keyword in C/C++).  It
+      is just a hint; it imposes no requirements on the inliner.</dd>
+
   <dt><tt>noinline</tt></dt>
   <dd>This attribute indicates that the inliner should never inline this
       function in any situation. This attribute may not be used together with