[llvm] r362132 - [DAGCombine] Use FoldConstantArithmetic() to perform C2-(A+C1) -> (C2-C1)-A fold

[Roman Lebedev via llvm-commits]

Author: lebedevri
Date: Thu May 30 12:27:26 2019
New Revision: 362132

URL: http://llvm.org/viewvc/llvm-project?rev=362132&view=rev
Log:
[DAGCombine] Use FoldConstantArithmetic() to perform C2-(A+C1) -> (C2-C1)-A fold

Summary:
No tests change, and i'm not sure how to test this, but it's better safe than sorry.

Reviewers: spatel, RKSimon, craig.topper, t.p.northover

Reviewed By: craig.topper

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62663

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=362132&r1=362131&r2=362132&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Thu May 30 12:27:26 2019
@@ -2868,7 +2868,9 @@ SDValue DAGCombiner::visitSUB(SDNode *N)
     SDValue N11 = N1.getOperand(1);
     if (isConstantOrConstantVector(N0, /* NoOpaques */ true) &&
         isConstantOrConstantVector(N11, /* NoOpaques */ true)) {
-      SDValue NewC = DAG.getNode(ISD::SUB, DL, VT, N0, N11);
+      SDValue NewC = DAG.FoldConstantArithmetic(ISD::SUB, DL, VT, N0.getNode(),
+                                                N11.getNode());
+      assert(NewC && "Constant folding failed");
       return DAG.getNode(ISD::SUB, DL, VT, NewC, N1.getOperand(0));
     }
   }