R600/SI: FMA is faster than fmul and fadd for f64

llvm-svn: 188136

2 files changed, 19 insertions, 0 deletions

diff --git a/llvm/lib/Target/R600/SIISelLowering.cpp b/llvm/lib/Target/R600/SIISelLowering.cpp
index b714fc19267..a76e6ee3145 100644
--- a/llvm/lib/Target/R600/SIISelLowering.cpp
+++ b/llvm/lib/Target/R600/SIISelLowering.cpp
@@ -338,6 +338,24 @@ MVT SITargetLowering::getScalarShiftAmountTy(EVT VT) const {
   return MVT::i32;
 }
 
+bool SITargetLowering::isFMAFasterThanFMulAndFAdd(EVT VT) const {
+  VT = VT.getScalarType();
+
+  if (!VT.isSimple())
+    return false;
+
+  switch (VT.getSimpleVT().SimpleTy) {
+  case MVT::f32:
+    return false; /* There is V_MAD_F32 for f32 */
+  case MVT::f64:
+    return true;
+  default:
+    break;
+  }
+
+  return false;
+}
+
 //===----------------------------------------------------------------------===//
 // Custom DAG Lowering Operations
 //===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Target/R600/SIISelLowering.h b/llvm/lib/Target/R600/SIISelLowering.h
index b4202c475d4..effbf1f85de 100644
--- a/llvm/lib/Target/R600/SIISelLowering.h
+++ b/llvm/lib/Target/R600/SIISelLowering.h
@@ -55,6 +55,7 @@ public:
                                               MachineBasicBlock * BB) const;
   virtual EVT getSetCCResultType(LLVMContext &Context, EVT VT) const;
   virtual MVT getScalarShiftAmountTy(EVT VT) const;
+  virtual bool isFMAFasterThanFMulAndFAdd(EVT VT) const;
   virtual SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const;
   virtual SDValue PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
   virtual SDNode *PostISelFolding(MachineSDNode *N, SelectionDAG &DAG) const;