Add a new intrinsic: llvm.fmuladd. This intrinsic represents a multiply-add

expression (a * b + c) that can be implemented as a fused multiply-add (fma)
if the target determines that this will be more efficient. This intrinsic
will be used to implement FP_CONTRACT support and an aggressive FMA formation
mode.

If your target has a fast FMA instruction you should override the
isFMAFasterThanMulAndAdd method in TargetLowering to return true.

llvm-svn: 158014

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index ab3ce48aacb..4152aa1ae16 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4932,6 +4932,27 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
                              getValue(I.getArgOperand(1)),
                              getValue(I.getArgOperand(2))));
     return 0;
+  case Intrinsic::fmuladd: {
+    EVT VT = TLI.getValueType(I.getType());
+    if (TLI.isOperationLegal(ISD::FMA, VT) && TLI.isFMAFasterThanMulAndAdd(VT)){
+      setValue(&I, DAG.getNode(ISD::FMA, dl,
+                               getValue(I.getArgOperand(0)).getValueType(),
+                               getValue(I.getArgOperand(0)),
+                               getValue(I.getArgOperand(1)),
+                               getValue(I.getArgOperand(2))));
+    } else {
+      SDValue Mul = DAG.getNode(ISD::FMUL, dl,
+                                getValue(I.getArgOperand(0)).getValueType(),
+                                getValue(I.getArgOperand(0)),
+                                getValue(I.getArgOperand(1)));
+      SDValue Add = DAG.getNode(ISD::FADD, dl,
+                                getValue(I.getArgOperand(0)).getValueType(),
+                                Mul,
+                                getValue(I.getArgOperand(2)));
+      setValue(&I, Add);
+    }
+    return 0;
+  }
   case Intrinsic::convert_to_fp16:
     setValue(&I, DAG.getNode(ISD::FP32_TO_FP16, dl,
                              MVT::i16, getValue(I.getArgOperand(0))));