[SystemZ] Be more careful about inverting CC masks (conditional loads)

Extend r187495 to conditional loads.  I split this out because the
easiest way seemed to be to force a particular operand order in
SystemZISelDAGToDAG.cpp.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187496 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 21 insertions, 0 deletions

diff --git a/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp b/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
index b7e966ff01..d9794b1d64 100644
--- a/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
+++ b/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
@@ -1012,6 +1012,27 @@ SDNode *SystemZDAGToDAGISel::Select(SDNode *Node) {
       }
     }
     break;
+
+  case SystemZISD::SELECT_CCMASK: {
+    SDValue Op0 = Node->getOperand(0);
+    SDValue Op1 = Node->getOperand(1);
+    // Prefer to put any load first, so that it can be matched as a
+    // conditional load.
+    if (Op1.getOpcode() == ISD::LOAD && Op0.getOpcode() != ISD::LOAD) {
+      SDValue CCValid = Node->getOperand(2);
+      SDValue CCMask = Node->getOperand(3);
+      uint64_t ConstCCValid =
+        cast<ConstantSDNode>(CCValid.getNode())->getZExtValue();
+      uint64_t ConstCCMask =
+        cast<ConstantSDNode>(CCMask.getNode())->getZExtValue();
+      // Invert the condition.
+      CCMask = CurDAG->getConstant(ConstCCValid ^ ConstCCMask,
+                                   CCMask.getValueType());
+      SDValue Op4 = Node->getOperand(4);
+      Node = CurDAG->UpdateNodeOperands(Node, Op1, Op0, CCValid, CCMask, Op4);
+    }
+    break;
+  }
   }
 
   // Select the default instruction