Refactor to expose RTLIB calls to targets.

fp128 is almost but not quite completely illegal as a type on AArch64. As a
result it needs to have a register class (for argument passing mainly), but all
operations need to be lowered to runtime calls. Currently there's no way for
targets to do this (without duplicating code), as the relevant functions are
hidden in SelectionDAG. This patch changes that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171971 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 155 insertions, 0 deletions

diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 34f3bc9055..d2da9b728d 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1012,6 +1012,161 @@ MVT::SimpleValueType TargetLowering::getCmpLibcallReturnType() const {
   return MVT::i32; // return the default value
 }
 
+/// Check whether a given call node is in tail position within its function. If
+/// so, it sets Chain to the input chain of the tail call.
+bool TargetLowering::isInTailCallPosition(SelectionDAG &DAG, SDNode *Node,
+                                          SDValue &Chain) const {
+  const Function *F = DAG.getMachineFunction().getFunction();
+
+  // Conservatively require the attributes of the call to match those of
+  // the return. Ignore noalias because it doesn't affect the call sequence.
+  Attribute CallerRetAttr = F->getAttributes().getRetAttributes();
+  if (AttrBuilder(CallerRetAttr)
+      .removeAttribute(Attribute::NoAlias).hasAttributes())
+    return false;
+
+  // It's not safe to eliminate the sign / zero extension of the return value.
+  if (CallerRetAttr.hasAttribute(Attribute::ZExt) ||
+      CallerRetAttr.hasAttribute(Attribute::SExt))
+    return false;
+
+  // Check if the only use is a function return node.
+  return isUsedByReturnOnly(Node, Chain);
+}
+
+
+/// Generate a libcall taking the given operands as arguments and returning a
+/// result of type RetVT.
+SDValue TargetLowering::makeLibCall(SelectionDAG &DAG,
+                                    RTLIB::Libcall LC, EVT RetVT,
+                                    const SDValue *Ops, unsigned NumOps,
+                                    bool isSigned, DebugLoc dl) const {
+  TargetLowering::ArgListTy Args;
+  Args.reserve(NumOps);
+
+  TargetLowering::ArgListEntry Entry;
+  for (unsigned i = 0; i != NumOps; ++i) {
+    Entry.Node = Ops[i];
+    Entry.Ty = Entry.Node.getValueType().getTypeForEVT(*DAG.getContext());
+    Entry.isSExt = isSigned;
+    Entry.isZExt = !isSigned;
+    Args.push_back(Entry);
+  }
+  SDValue Callee = DAG.getExternalSymbol(getLibcallName(LC), getPointerTy());
+
+  Type *RetTy = RetVT.getTypeForEVT(*DAG.getContext());
+  TargetLowering::
+  CallLoweringInfo CLI(DAG.getEntryNode(), RetTy, isSigned, !isSigned, false,
+                    false, 0, getLibcallCallingConv(LC),
+                    /*isTailCall=*/false,
+                    /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
+                    Callee, Args, DAG, dl);
+  std::pair<SDValue,SDValue> CallInfo = LowerCallTo(CLI);
+
+  return CallInfo.first;
+}
+
+
+/// SoftenSetCCOperands - Soften the operands of a comparison.  This code is
+/// shared among BR_CC, SELECT_CC, and SETCC handlers.
+void TargetLowering::softenSetCCOperands(SelectionDAG &DAG, EVT VT,
+                                         SDValue &NewLHS, SDValue &NewRHS,
+                                         ISD::CondCode &CCCode,
+                                         DebugLoc dl) const {
+  assert((VT == MVT::f32 || VT == MVT::f64 || VT == MVT::f128)
+         && "Unsupported setcc type!");
+
+  // Expand into one or more soft-fp libcall(s).
+  RTLIB::Libcall LC1 = RTLIB::UNKNOWN_LIBCALL, LC2 = RTLIB::UNKNOWN_LIBCALL;
+  switch (CCCode) {
+  case ISD::SETEQ:
+  case ISD::SETOEQ:
+    LC1 = (VT == MVT::f32) ? RTLIB::OEQ_F32 :
+          (VT == MVT::f64) ? RTLIB::OEQ_F64 : RTLIB::OEQ_F128;
+    break;
+  case ISD::SETNE:
+  case ISD::SETUNE:
+    LC1 = (VT == MVT::f32) ? RTLIB::UNE_F32 :
+          (VT == MVT::f64) ? RTLIB::UNE_F64 : RTLIB::UNE_F128;
+    break;
+  case ISD::SETGE:
+  case ISD::SETOGE:
+    LC1 = (VT == MVT::f32) ? RTLIB::OGE_F32 :
+          (VT == MVT::f64) ? RTLIB::OGE_F64 : RTLIB::OGE_F128;
+    break;
+  case ISD::SETLT:
+  case ISD::SETOLT:
+    LC1 = (VT == MVT::f32) ? RTLIB::OLT_F32 :
+          (VT == MVT::f64) ? RTLIB::OLT_F64 : RTLIB::OLT_F128;
+    break;
+  case ISD::SETLE:
+  case ISD::SETOLE:
+    LC1 = (VT == MVT::f32) ? RTLIB::OLE_F32 :
+          (VT == MVT::f64) ? RTLIB::OLE_F64 : RTLIB::OLE_F128;
+    break;
+  case ISD::SETGT:
+  case ISD::SETOGT:
+    LC1 = (VT == MVT::f32) ? RTLIB::OGT_F32 :
+          (VT == MVT::f64) ? RTLIB::OGT_F64 : RTLIB::OGT_F128;
+    break;
+  case ISD::SETUO:
+    LC1 = (VT == MVT::f32) ? RTLIB::UO_F32 :
+          (VT == MVT::f64) ? RTLIB::UO_F64 : RTLIB::UO_F128;
+    break;
+  case ISD::SETO:
+    LC1 = (VT == MVT::f32) ? RTLIB::O_F32 :
+          (VT == MVT::f64) ? RTLIB::O_F64 : RTLIB::O_F128;
+    break;
+  default:
+    LC1 = (VT == MVT::f32) ? RTLIB::UO_F32 :
+          (VT == MVT::f64) ? RTLIB::UO_F64 : RTLIB::UO_F128;
+    switch (CCCode) {
+    case ISD::SETONE:
+      // SETONE = SETOLT | SETOGT
+      LC1 = (VT == MVT::f32) ? RTLIB::OLT_F32 :
+            (VT == MVT::f64) ? RTLIB::OLT_F64 : RTLIB::OLT_F128;
+      // Fallthrough
+    case ISD::SETUGT:
+      LC2 = (VT == MVT::f32) ? RTLIB::OGT_F32 :
+            (VT == MVT::f64) ? RTLIB::OGT_F64 : RTLIB::OGT_F128;
+      break;
+    case ISD::SETUGE:
+      LC2 = (VT == MVT::f32) ? RTLIB::OGE_F32 :
+            (VT == MVT::f64) ? RTLIB::OGE_F64 : RTLIB::OGE_F128;
+      break;
+    case ISD::SETULT:
+      LC2 = (VT == MVT::f32) ? RTLIB::OLT_F32 :
+            (VT == MVT::f64) ? RTLIB::OLT_F64 : RTLIB::OLT_F128;
+      break;
+    case ISD::SETULE:
+      LC2 = (VT == MVT::f32) ? RTLIB::OLE_F32 :
+            (VT == MVT::f64) ? RTLIB::OLE_F64 : RTLIB::OLE_F128;
+      break;
+    case ISD::SETUEQ:
+      LC2 = (VT == MVT::f32) ? RTLIB::OEQ_F32 :
+            (VT == MVT::f64) ? RTLIB::OEQ_F64 : RTLIB::OEQ_F128;
+      break;
+    default: llvm_unreachable("Do not know how to soften this setcc!");
+    }
+  }
+
+  // Use the target specific return value for comparions lib calls.
+  EVT RetVT = getCmpLibcallReturnType();
+  SDValue Ops[2] = { NewLHS, NewRHS };
+  NewLHS = makeLibCall(DAG, LC1, RetVT, Ops, 2, false/*sign irrelevant*/, dl);
+  NewRHS = DAG.getConstant(0, RetVT);
+  CCCode = getCmpLibcallCC(LC1);
+  if (LC2 != RTLIB::UNKNOWN_LIBCALL) {
+    SDValue Tmp = DAG.getNode(ISD::SETCC, dl, getSetCCResultType(RetVT),
+                              NewLHS, NewRHS, DAG.getCondCode(CCCode));
+    NewLHS = makeLibCall(DAG, LC2, RetVT, Ops, 2, false/*sign irrelevant*/, dl);
+    NewLHS = DAG.getNode(ISD::SETCC, dl, getSetCCResultType(RetVT), NewLHS,
+                         NewRHS, DAG.getCondCode(getCmpLibcallCC(LC2)));
+    NewLHS = DAG.getNode(ISD::OR, dl, Tmp.getValueType(), Tmp, NewLHS);
+    NewRHS = SDValue();
+  }
+}
+
 /// getVectorTypeBreakdown - Vector types are broken down into some number of
 /// legal first class types.  For example, MVT::v8f32 maps to 2 MVT::v4f32
 /// with Altivec or SSE1, or 8 promoted MVT::f64 values with the X86 FP stack.