Make blockaddress(@func, null) be valid, and make 'deleting a basic 
block with a blockaddress still referring to it' replace the invalid 
blockaddress with a new blockaddress(@func, null) instead of a 
inttoptr(1).

This changes the bitcode encoding format, and still needs codegen 
support (this should produce a non-zero value, referring to the entry
block of the function would also be quite reasonable).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85678 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/LangRef.html b/docs/LangRef.html
index af0e564..23c07c7 100644
--- a/docs/LangRef.html
+++ b/docs/LangRef.html
@@ -2176,11 +2176,13 @@
     Blocks</a></div>
 <div class="doc_text">
 
-<p><b><tt>blockaddress(@function, %block)</tt></b></p>
+<p><b><tt>blockaddress(@function, %block)</tt></b><br>
+   <b><tt>blockaddress(@function, null)</tt></b></p>
 
 <p>The '<tt>blockaddress</tt>' constant computes the address of the specified
    basic block in the specified function, and always has an i8* type.  Taking
-   the address of the entry block is illegal.</p>
+   the address of the entry block is illegal.  The BasicBlock operand may also
+   be null.</p>
      
 <p>This value only has defined behavior when used as an operand to the
    '<a href="#i_indirectbr"><tt>indirectbr</tt></a>' instruction or for comparisons