Teach the AArch64 backend to handle f16

This allows the AArch64 backend to handle fadd, fsub, fmul and fdiv
operations on f16 (half-precision) types by promoting to f32.

llvm-svn: 215891

2 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 232cbd81f76..ea88264d95f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -4264,6 +4264,9 @@ void SelectionDAGLegalize::PromoteNode(SDNode *Node) {
                                   Tmp1, Tmp2, Node->getOperand(2)));
     break;
   }
+  case ISD::FADD:
+  case ISD::FSUB:
+  case ISD::FMUL:
   case ISD::FDIV:
   case ISD::FREM:
   case ISD::FPOW: {
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index e277a5e0780..49e0ed2e2ab 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -278,6 +278,15 @@ AArch64TargetLowering::AArch64TargetLowering(TargetMachine &TM)
   setOperationAction(ISD::FCOPYSIGN, MVT::f64, Custom);
   setOperationAction(ISD::FCOPYSIGN, MVT::f32, Custom);
 
+  // f16 is storage-only, so we promote operations to f32 if we know this is
+  // valid, and ignore them otherwise. The operations not mentioned here will
+  // fail to select, but this is not a major problem as no source language
+  // should be emitting native f16 operations yet.
+  setOperationAction(ISD::FADD, MVT::f16, Promote);
+  setOperationAction(ISD::FDIV, MVT::f16, Promote);
+  setOperationAction(ISD::FMUL, MVT::f16, Promote);
+  setOperationAction(ISD::FSUB, MVT::f16, Promote);
+
   // AArch64 has implementations of a lot of rounding-like FP operations.
   static MVT RoundingTypes[] = { MVT::f32, MVT::f64};
   for (unsigned I = 0; I < array_lengthof(RoundingTypes); ++I) {