[PowerPC] custom lower `v2f64 fpext v2f32`

Reduces scalarization overhead via custom lowering of v2f64 fpext v2f32.

eg. For the following IR
  %0 = load <2 x float>, <2 x float>* %Ptr, align 8
  %1 = fpext <2 x float> %0 to <2 x double>
  ret <2 x double> %1

Pre custom lowering:
  ld r3, 0(r3)
  mtvsrd f0, r3
  xxswapd vs34, vs0
  xscvspdpn f0, vs0
  xxsldwi vs1, vs34, vs34, 3
  xscvspdpn f1, vs1
  xxmrghd vs34, vs0, vs1

After custom lowering:
  lfd f0, 0(r3)
  xxmrghw vs0, vs0, vs0
  xvcvspdp vs34, vs0

Differential Revision: https://reviews.llvm.org/D57857

llvm-svn: 360429

3 files changed, 84 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 9ff817e2f50..79be3265892 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -877,6 +877,7 @@ PPCTargetLowering::PPCTargetLowering(const PPCTargetMachine &TM,
         setOperationAction(ISD::FPOWI, MVT::f128, Expand);
         setOperationAction(ISD::FREM, MVT::f128, Expand);
       }
+      setOperationAction(ISD::FP_EXTEND, MVT::v2f32, Custom);
 
     }
 
@@ -1378,6 +1379,8 @@ const char *PPCTargetLowering::getTargetNodeName(unsigned Opcode) const {
   case PPCISD::QVLFSb:          return "PPCISD::QVLFSb";
   case PPCISD::BUILD_FP128:     return "PPCISD::BUILD_FP128";
   case PPCISD::EXTSWSLI:        return "PPCISD::EXTSWSLI";
+  case PPCISD::LD_VSX_LH:       return "PPCISD::LD_VSX_LH";
+  case PPCISD::FP_EXTEND_LH:    return "PPCISD::FP_EXTEND_LH";
   }
   return nullptr;
 }
@@ -9608,6 +9611,59 @@ SDValue PPCTargetLowering::LowerABS(SDValue Op, SelectionDAG &DAG) const {
   return BuildIntrinsicOp(BifID, X, Y, DAG, dl, VT);
 }
 
+// Custom lowering for fpext vf32 to v2f64
+SDValue PPCTargetLowering::LowerFP_EXTEND(SDValue Op, SelectionDAG &DAG) const {
+
+  assert(Op.getOpcode() == ISD::FP_EXTEND &&
+         "Should only be called for ISD::FP_EXTEND");
+
+  // We only want to custom lower an extend from v2f32 to v2f64.
+  if (Op.getValueType() != MVT::v2f64 ||
+      Op.getOperand(0).getValueType() != MVT::v2f32)
+    return SDValue();
+
+  SDLoc dl(Op);
+  SDValue Op0 = Op.getOperand(0);
+
+  switch (Op0.getOpcode()) {
+  default:
+    return SDValue();
+  case ISD::FADD:
+  case ISD::FMUL:
+  case ISD::FSUB: {
+    SDValue NewLoad[2];
+    for (unsigned i = 0, ie = Op0.getNumOperands(); i != ie; ++i) {
+      // Ensure both input are loads.
+      SDValue LdOp = Op0.getOperand(i);
+      if (LdOp.getOpcode() != ISD::LOAD)
+        return SDValue();
+      // Generate new load node.
+      LoadSDNode *LD = cast<LoadSDNode>(LdOp);
+      SDValue LoadOps[] = { LD->getChain(), LD->getBasePtr() };
+      NewLoad[i] =
+        DAG.getMemIntrinsicNode(PPCISD::LD_VSX_LH, dl,
+                                DAG.getVTList(MVT::v4f32, MVT::Other),
+                                LoadOps, LD->getMemoryVT(),
+                                LD->getMemOperand());
+    }
+    SDValue NewOp = DAG.getNode(Op0.getOpcode(), SDLoc(Op0), MVT::v4f32,
+                              NewLoad[0], NewLoad[1],
+                              Op0.getNode()->getFlags());
+    return DAG.getNode(PPCISD::FP_EXTEND_LH, dl, MVT::v2f64, NewOp);
+  }
+  case ISD::LOAD: {
+    LoadSDNode *LD = cast<LoadSDNode>(Op0);
+    SDValue LoadOps[] = { LD->getChain(), LD->getBasePtr() };
+    SDValue NewLd =
+      DAG.getMemIntrinsicNode(PPCISD::LD_VSX_LH, dl,
+                              DAG.getVTList(MVT::v4f32, MVT::Other),
+                              LoadOps, LD->getMemoryVT(), LD->getMemOperand());
+    return DAG.getNode(PPCISD::FP_EXTEND_LH, dl, MVT::v2f64, NewLd);
+  }
+  }
+  llvm_unreachable("ERROR:Should return for all cases within swtich.");
+}
+
 /// LowerOperation - Provide custom lowering hooks for some operations.
 ///
 SDValue PPCTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
@@ -9661,6 +9717,7 @@ SDValue PPCTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
   case ISD::INSERT_VECTOR_ELT:  return LowerINSERT_VECTOR_ELT(Op, DAG);
   case ISD::MUL:                return LowerMUL(Op, DAG);
   case ISD::ABS:                return LowerABS(Op, DAG);
+  case ISD::FP_EXTEND:          return LowerFP_EXTEND(Op, DAG);
 
   // For counter-based loop handling.
   case ISD::INTRINSIC_W_CHAIN:  return SDValue();
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index 208306c577e..cf812a25085 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -404,6 +404,9 @@ namespace llvm {
       /// representation.
       QBFLT,
 
+      /// Custom extend v4f32 to v2f64.
+      FP_EXTEND_LH,
+
       /// CHAIN = STBRX CHAIN, GPRC, Ptr, Type - This is a
       /// byte-swapping store instruction.  It byte-swaps the low "Type" bits of
       /// the GPRC input, then stores it through Ptr.  Type can be either i16 or
@@ -445,6 +448,10 @@ namespace llvm {
       /// an xxswapd.
       LXVD2X,
 
+      /// VSRC, CHAIN = LD_VSX_LH CHAIN, Ptr - This is a floating-point load of a
+      /// v2f32 value into the lower half of a VSR register.
+      LD_VSX_LH,
+
       /// CHAIN = STXVD2X CHAIN, VSRC, Ptr - Occurs only for little endian.
       /// Maps directly to an stxvd2x instruction that will be preceded by
       /// an xxswapd.
@@ -1021,6 +1028,7 @@ namespace llvm {
     SDValue LowerSIGN_EXTEND_INREG(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerMUL(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerABS(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerFP_EXTEND(SDValue Op, SelectionDAG &DAG) const;
 
     SDValue LowerVectorLoad(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerVectorStore(SDValue Op, SelectionDAG &DAG) const;
diff --git a/llvm/lib/Target/PowerPC/PPCInstrVSX.td b/llvm/lib/Target/PowerPC/PPCInstrVSX.td
index d874f30c7e8..6b97435527a 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrVSX.td
+++ b/llvm/lib/Target/PowerPC/PPCInstrVSX.td
@@ -53,6 +53,15 @@ def PPCRegSPILLTOVSRRCAsmOperand : AsmOperandClass {
 def spilltovsrrc : RegisterOperand<SPILLTOVSRRC> {
   let ParserMatchClass = PPCRegSPILLTOVSRRCAsmOperand;
 }
+
+def SDT_PPCldvsxlh : SDTypeProfile<1, 1, [
+  SDTCisVT<0, v4f32>, SDTCisPtrTy<1>
+]>;
+
+def SDT_PPCfpextlh : SDTypeProfile<1, 1, [
+  SDTCisVT<0, v2f64>, SDTCisVT<1, v4f32>
+]>;
+
 // Little-endian-specific nodes.
 def SDT_PPClxvd2x : SDTypeProfile<1, 1, [
   SDTCisVT<0, v2f64>, SDTCisPtrTy<1>
@@ -84,6 +93,10 @@ def PPCuvec2fp: SDNode<"PPCISD::UINT_VEC_TO_FP", SDTVecConv, []>;
 def PPCswapNoChain : SDNode<"PPCISD::SWAP_NO_CHAIN", SDT_PPCxxswapd>;
 def PPCvabsd : SDNode<"PPCISD::VABSD", SDTVabsd, []>;
 
+def PPCfpextlh : SDNode<"PPCISD::FP_EXTEND_LH", SDT_PPCfpextlh, []>;
+def PPCldvsxlh : SDNode<"PPCISD::LD_VSX_LH", SDT_PPCldvsxlh,
+                        [SDNPHasChain, SDNPMayLoad, SDNPMemOperand]>;
+
 multiclass XX3Form_Rcr<bits<6> opcode, bits<7> xo, string asmbase,
                     string asmstr, InstrItinClass itin, Intrinsic Int,
                     ValueType OutTy, ValueType InTy> {
@@ -1060,6 +1073,8 @@ def : Pat<(v2f64 (PPCuvec2fp v4i32:$C, 0)),
 def : Pat<(v2f64 (PPCuvec2fp v4i32:$C, 1)),
           (v2f64 (XVCVUXWDP (v2i64 (XXMRGLW $C, $C))))>;
 
+def : Pat<(v2f64 (PPCfpextlh v4f32:$C)), (XVCVSPDP (XXMRGHW $C, $C))>;
+
 // Loads.
 let Predicates = [HasVSX, HasOnlySwappingMemOps] in {
   def : Pat<(v2f64 (PPClxvd2x xoaddr:$src)), (LXVD2X xoaddr:$src)>;
@@ -3266,6 +3281,10 @@ let AddedComplexity = 400, Predicates = [HasP9Vector] in {
   def : Pat<(f32 (fpround (f64 (extloadf32 ixaddr:$src)))),
             (f32 (DFLOADf32 ixaddr:$src))>;
 
+  def : Pat<(v4f32 (PPCldvsxlh xaddr:$src)),
+            (COPY_TO_REGCLASS (XFLOADf64 xaddr:$src), VSRC)>;
+  def : Pat<(v4f32 (PPCldvsxlh ixaddr:$src)),
+            (COPY_TO_REGCLASS (DFLOADf64 ixaddr:$src), VSRC)>;
 
   let AddedComplexity = 400 in {
   // The following pseudoinstructions are used to ensure the utilization