[legalizetypes] Push fp16 -> fp32 extension node to worklist.

Summary:
This way, the type legalization machinery will take care of registering
the result of this node properly.

This patches fixes all failing fp16 test cases  with expensive checks.
(CodeGen/ARM/fp16-promote.ll, CodeGen/ARM/fp16.ll, CodeGen/X86/cvt16.ll
CodeGen/X86/soft-fp.ll) 


Reviewers: t.p.northover, baldrick, olista01, bogner, jmolloy, davidxl, ab, echristo, hfinkel

Reviewed By: hfinkel

Subscribers: mehdi_amini, hfinkel, davide, RKSimon, aemerson, llvm-commits

Differential Revision: https://reviews.llvm.org/D28195

llvm-svn: 293765

Author: fhahn

llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp

@@ -459,7 +459,7 @@ SDValue DAGTypeLegalizer::SoftenFloatRes_FP_EXTEND(SDNode *N) {
   if (Op.getValueType() == MVT::f16 && N->getValueType(0) != MVT::f32) {
     Op = DAG.getNode(ISD::FP_EXTEND, SDLoc(N), MVT::f32, Op);
     if (getTypeAction(MVT::f32) == TargetLowering::TypeSoftenFloat)
-      SoftenFloatResult(Op.getNode(), 0);
+      AddToWorklist(Op.getNode());
   }
 
   if (getTypeAction(Op.getValueType()) == TargetLowering::TypePromoteFloat) {
@@ -472,8 +472,6 @@ SDValue DAGTypeLegalizer::SoftenFloatRes_FP_EXTEND(SDNode *N) {
   }
 
   RTLIB::Libcall LC = RTLIB::getFPEXT(Op.getValueType(), N->getValueType(0));
-  if (getTypeAction(Op.getValueType()) == TargetLowering::TypeSoftenFloat)
-    Op = GetSoftenedFloat(Op);
   assert(LC != RTLIB::UNKNOWN_LIBCALL && "Unsupported FP_EXTEND!");
   return TLI.makeLibCall(DAG, LC, NVT, Op, false, SDLoc(N)).first;
 }

llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp

@@ -199,8 +199,7 @@ bool DAGTypeLegalizer::run() {
   // non-leaves.
   for (SDNode &Node : DAG.allnodes()) {
     if (Node.getNumOperands() == 0) {
-      Node.setNodeId(ReadyToProcess);
-      Worklist.push_back(&Node);
+      AddToWorklist(&Node);
     } else {
       Node.setNodeId(Unanalyzed);
     }

llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h

@@ -191,6 +191,11 @@ class LLVM_LIBRARY_VISIBILITY DAGTypeLegalizer {
   void SplitInteger(SDValue Op, EVT LoVT, EVT HiVT,
                     SDValue &Lo, SDValue &Hi);
 
+  void AddToWorklist(SDNode *N) {
+    N->setNodeId(ReadyToProcess);
+    Worklist.push_back(N);
+  }
+
   //===--------------------------------------------------------------------===//
   // Integer Promotion Support: LegalizeIntegerTypes.cpp
   //===--------------------------------------------------------------------===//