Add Constant Hoisting Pass

Retry commit r200022 with a fix for the build bot errors. Constant expressions
have (unlike instructions) module scope use lists and therefore may have users
in different functions. The fix is to simply ignore these out-of-function uses.

llvm-svn: 200034

1 files changed, 6 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 69e2ce198e0..3fa2a32e868 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3212,11 +3212,14 @@ SDValue DAGCombiner::visitOR(SDNode *N) {
   if (N1C && N0.getOpcode() == ISD::AND && N0.getNode()->hasOneUse() &&
              isa<ConstantSDNode>(N0.getOperand(1))) {
     ConstantSDNode *C1 = cast<ConstantSDNode>(N0.getOperand(1));
-    if ((C1->getAPIntValue() & N1C->getAPIntValue()) != 0)
+    if ((C1->getAPIntValue() & N1C->getAPIntValue()) != 0) {
+      SDValue COR = DAG.FoldConstantArithmetic(ISD::OR, VT, N1C, C1);
+      if (!COR.getNode())
+        return SDValue();
       return DAG.getNode(ISD::AND, SDLoc(N), VT,
                          DAG.getNode(ISD::OR, SDLoc(N0), VT,
-                                     N0.getOperand(0), N1),
-                         DAG.FoldConstantArithmetic(ISD::OR, VT, N1C, C1));
+                                     N0.getOperand(0), N1), COR);
+    }
   }
   // fold (or (setcc x), (setcc y)) -> (setcc (or x, y))
   if (isSetCCEquivalent(N0, LL, LR, CC0) && isSetCCEquivalent(N1, RL, RR, CC1)){