[Intrinsic] Signed Saturation Addition Intrinsic

Add an intrinsic that takes 2 integers and perform saturation addition on them.

This is a part of implementing fixed point arithmetic in clang where some of
the more complex operations will be implemented as intrinsics.

Differential Revision: https://reviews.llvm.org/D53053

llvm-svn: 344629

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 07a37a5092a..71d124c74ce 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1115,6 +1115,10 @@ void SelectionDAGLegalize::LegalizeOp(SDNode *Node) {
     Action = TLI.getStrictFPOperationAction(Node->getOpcode(),
                                             Node->getValueType(0));
     break;
+  case ISD::SADDSAT: {
+    Action = TLI.getOperationAction(Node->getOpcode(), Node->getValueType(0));
+    break;
+  }
   case ISD::MSCATTER:
     Action = TLI.getOperationAction(Node->getOpcode(),
                     cast<MaskedScatterSDNode>(Node)->getValue().getValueType());
@@ -3451,6 +3455,10 @@ bool SelectionDAGLegalize::ExpandNode(SDNode *Node) {
     }
     break;
   }
+  case ISD::SADDSAT: {
+    Results.push_back(TLI.getExpandedSignedSaturationAddition(Node, DAG));
+    break;
+  }
   case ISD::SADDO:
   case ISD::SSUBO: {
     SDValue LHS = Node->getOperand(0);