[Hexagon] Implement HexagonTargetLowering::CanLowerReturn

Patch by Michael Wu.

Differential Revision: https://reviews.llvm.org/D32000

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300199 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Krzysztof Parzyszek

lib/Target/Hexagon/HexagonISelLowering.cpp

@@ -485,9 +485,7 @@ static bool RetCC_Hexagon32(unsigned ValNo, MVT ValVT,
     }
   }
 
-  unsigned Offset = State.AllocateStack(4, 4);
-  State.addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
-  return false;
+  return true;
 }
 
 static bool RetCC_Hexagon64(unsigned ValNo, MVT ValVT,
@@ -500,9 +498,7 @@ static bool RetCC_Hexagon64(unsigned ValNo, MVT ValVT,
     }
   }
 
-  unsigned Offset = State.AllocateStack(8, 8);
-  State.addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
-  return false;
+  return true;
 }
 
 static bool RetCC_HexagonVector(unsigned ValNo, MVT ValVT,
@@ -513,7 +509,6 @@ static bool RetCC_HexagonVector(unsigned ValNo, MVT ValVT,
   bool UseHVX = HST.useHVXOps();
   bool UseHVXDbl = HST.useHVXDblOps();
 
-  unsigned OffSiz = 64;
   if (LocVT == MVT::v16i32) {
     if (unsigned Reg = State.AllocateReg(Hexagon::V0)) {
       State.addLoc(CCValAssign::getReg(ValNo, ValVT, Reg, LocVT, LocInfo));
@@ -525,18 +520,14 @@ static bool RetCC_HexagonVector(unsigned ValNo, MVT ValVT,
       State.addLoc(CCValAssign::getReg(ValNo, ValVT, Reg, LocVT, LocInfo));
       return false;
     }
-    OffSiz = 128;
   } else if (LocVT == MVT::v64i32) {
     if (unsigned Reg = State.AllocateReg(Hexagon::W0)) {
       State.addLoc(CCValAssign::getReg(ValNo, ValVT, Reg, LocVT, LocInfo));
       return false;
     }
-    OffSiz = 256;
   }
 
-  unsigned Offset = State.AllocateStack(OffSiz, OffSiz);
-  State.addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
-  return false;
+  return true;
 }
 
 void HexagonTargetLowering::promoteLdStType(MVT VT, MVT PromotedLdStVT) {
@@ -592,6 +583,16 @@ static bool isHvxVectorType(MVT Ty) {
   }
 }
 
+bool
+HexagonTargetLowering::CanLowerReturn(
+    CallingConv::ID CallConv, MachineFunction &MF, bool isVarArg,
+    const SmallVectorImpl<ISD::OutputArg> &Outs,
+    LLVMContext &Context) const {
+  SmallVector<CCValAssign, 16> RVLocs;
+  CCState CCInfo(CallConv, isVarArg, MF, RVLocs, Context);
+  return CCInfo.CheckReturn(Outs, RetCC_Hexagon);
+}
+
 // LowerReturn - Lower ISD::RET. If a struct is larger than 8 bytes and is
 // passed by value, the function prototype is modified to return void and
 // the value is stored in memory pointed by a pointer passed by caller.

lib/Target/Hexagon/HexagonISelLowering.h

@@ -185,6 +185,11 @@ namespace HexagonISD {
     SDValue LowerRETURNADDR(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerLOAD(SDValue Op, SelectionDAG &DAG) const;
 
+    bool CanLowerReturn(CallingConv::ID CallConv,
+                        MachineFunction &MF, bool isVarArg,
+                        const SmallVectorImpl<ISD::OutputArg> &Outs,
+                        LLVMContext &Context) const override;
+
     SDValue LowerReturn(SDValue Chain, CallingConv::ID CallConv, bool isVarArg,
                         const SmallVectorImpl<ISD::OutputArg> &Outs,
                         const SmallVectorImpl<SDValue> &OutVals,