[X86] Make X86TargetLowering::BuildFILD return a std::pair of SDValues so we explicitly return the chain instead of calling getValue on the single SDValue.

We shouldn't assume that the returned result can be used to get
the other result.

This is prep-work for strict FP where we will also need to pass
the chain result along in more cases.

2 files changed, 12 insertions, 11 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index a50d30fca4d..4dc2ff48178 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -18557,10 +18557,10 @@ SDValue X86TargetLowering::LowerSINT_TO_FP(SDValue Op,
   SDValue Chain = DAG.getStore(
       DAG.getEntryNode(), dl, ValueToStore, StackSlot,
       MachinePointerInfo::getFixedStack(DAG.getMachineFunction(), SSFI));
-  return BuildFILD(Op, SrcVT, Chain, StackSlot, DAG);
+  return BuildFILD(Op, SrcVT, Chain, StackSlot, DAG).first;
 }
 
-SDValue X86TargetLowering::BuildFILD(SDValue Op, EVT SrcVT, SDValue Chain,
+std::pair<SDValue, SDValue> X86TargetLowering::BuildFILD(SDValue Op, EVT SrcVT, SDValue Chain,
                                      SDValue StackSlot,
                                      SelectionDAG &DAG) const {
   // Build the FILD
@@ -18589,9 +18589,9 @@ SDValue X86TargetLowering::BuildFILD(SDValue Op, EVT SrcVT, SDValue Chain,
   SDValue Result =
       DAG.getMemIntrinsicNode(useSSE ? X86ISD::FILD_FLAG : X86ISD::FILD, DL,
                               Tys, FILDOps, SrcVT, LoadMMO);
+  Chain = Result.getValue(1);
 
   if (useSSE) {
-    Chain = Result.getValue(1);
     SDValue InFlag = Result.getValue(2);
 
     // FIXME: Currently the FST is glued to the FILD_FLAG. This
@@ -18613,9 +18613,10 @@ SDValue X86TargetLowering::BuildFILD(SDValue Op, EVT SrcVT, SDValue Chain,
     Result = DAG.getLoad(
         Op.getValueType(), DL, Chain, StackSlot,
         MachinePointerInfo::getFixedStack(DAG.getMachineFunction(), SSFI));
+    Chain = Result.getValue(1);
   }
 
-  return Result;
+  return { Result, Chain };
 }
 
 /// Horizontal vector math instructions may be slower than normal math with
@@ -18927,8 +18928,7 @@ SDValue X86TargetLowering::LowerUINT_TO_FP(SDValue Op,
                                   StackSlot, MachinePointerInfo());
     SDValue Store2 = DAG.getStore(Store1, dl, DAG.getConstant(0, dl, MVT::i32),
                                   OffsetSlot, MachinePointerInfo());
-    SDValue Fild = BuildFILD(Op, MVT::i64, Store2, StackSlot, DAG);
-    return Fild;
+    return BuildFILD(Op, MVT::i64, Store2, StackSlot, DAG).first;
   }
 
   assert(SrcVT == MVT::i64 && "Unexpected type in UINT_TO_FP");
@@ -43480,10 +43480,10 @@ static SDValue combineSIntToFP(SDNode *N, SelectionDAG &DAG,
     if (Ld->isSimple() && !VT.isVector() &&
         ISD::isNON_EXTLoad(Op0.getNode()) && Op0.hasOneUse() &&
         !Subtarget.is64Bit() && LdVT == MVT::i64) {
-      SDValue FILDChain = Subtarget.getTargetLowering()->BuildFILD(
+      std::pair<SDValue, SDValue> Tmp = Subtarget.getTargetLowering()->BuildFILD(
           SDValue(N, 0), LdVT, Ld->getChain(), Op0, DAG);
-      DAG.ReplaceAllUsesOfValueWith(Op0.getValue(1), FILDChain.getValue(1));
-      return FILDChain;
+      DAG.ReplaceAllUsesOfValueWith(Op0.getValue(1), Tmp.second);
+      return Tmp.first;
     }
   }
 
diff --git a/llvm/lib/Target/X86/X86ISelLowering.h b/llvm/lib/Target/X86/X86ISelLowering.h
index 82f56f895a1..2bf4977449d 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.h
+++ b/llvm/lib/Target/X86/X86ISelLowering.h
@@ -1201,8 +1201,9 @@ namespace llvm {
     /// offset as appropriate.
     Value *getSafeStackPointerLocation(IRBuilder<> &IRB) const override;
 
-    SDValue BuildFILD(SDValue Op, EVT SrcVT, SDValue Chain, SDValue StackSlot,
-                      SelectionDAG &DAG) const;
+    std::pair<SDValue, SDValue> BuildFILD(SDValue Op, EVT SrcVT, SDValue Chain,
+                                          SDValue StackSlot,
+                                          SelectionDAG &DAG) const;
 
     bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const override;