[llvm] r342851 - [DAGCombiner] Clarify a comment. NFC

[Craig Topper via llvm-commits]

Author: ctopper
Date: Sun Sep 23 14:17:56 2018
New Revision: 342851

URL: http://llvm.org/viewvc/llvm-project?rev=342851&view=rev
Log:
[DAGCombiner] Clarify a comment. NFC

This comment was misleading about why we were restricting to before legalize types. The reason given would only apply to before legalize ops. But there is a before legalize types reason that should also be listed.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=342851&r1=342850&r2=342851&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Sun Sep 23 14:17:56 2018
@@ -9843,8 +9843,10 @@ SDValue DAGCombiner::visitBITCAST(SDNode
     return DAG.getUNDEF(VT);
 
   // If the input is a BUILD_VECTOR with all constant elements, fold this now.
-  // Only do this before legalize, since afterward the target may be depending
-  // on the bitconvert.
+  // Only do this before legalize types, since we might create an illegal
+  // scalar type. Even if we knew we wouldn't create an illegal scalar type
+  // we can only do this before legalize ops, since the target maybe
+  // depending on the bitcast.
   // First check to see if this is all constant.
   if (!LegalTypes &&
       N0.getOpcode() == ISD::BUILD_VECTOR && N0.getNode()->hasOneUse() &&