Restore hasPostISelHook tblgen flag.

No functionality change. The hook makes it explicit which patterns
require "special" handling. i.e. it self-documents tblgen
deficiencies. I plan to add verification in ExpandISelPseudos and
Thumb2SizeReduce to catch any missing hasPostISelHooks. Otherwise it's
too fragile.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140160 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index eebf2b2..e2e906a 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -763,7 +763,8 @@
     }
 
   // Run post-isel target hook to adjust this instruction if needed.
-  TLI->AdjustInstrPostInstrSelection(MI, Node);
+  if (II.hasPostISelHook())
+    TLI->AdjustInstrPostInstrSelection(MI, Node);
 }
 
 /// EmitSpecialNode - Generate machine code for a target-independent node and