[X86][CodeGen] Add base atan2 intrinsic lowering (p4)

tex3d · tex3d · commit 9b3ffe09a150 · 2024-10-11T15:32:51.000-07:00
This change is part of this proposal: https://discourse.llvm.org/t/rfc-all-the-math-intrinsics/78294 Based on example PR llvm#96222 and fix PR llvm#101268, with some differences due to 2-arg intrinsic and intermediate refactor (RuntimeLibCalls.cpp). - Add llvm.experimental.constrained.atan2 - Intrinsics.td, ConstrainedOps.def, LangRef.rst - Add to ISDOpcodes.h and TargetSelectionDAG.td, connect to intrinsic in BasicTTIImpl.h, and LibFunc_ in SelectionDAGBuilder.cpp, and map generic op in SelectionDAGCompat.td - Update LegalizeDAG.cpp, LegalizeFloatTypes.cpp, LegalizeVectorOps.cpp, and LegalizeVectorTypes.cpp - Update isKnownNeverNaN in SelectionDAG.cpp - Update SelectionDAGDumper.cpp - Update libcalls - RuntimeLibcalls.def, RuntimeLibcalls.cpp, LegalizerHelper.cpp - Update isKnownNeverNaN for generic opcode in GlobalISel/Utils.cpp - TargetLoweringBase.cpp - Expand for vectors, promote f16 - X86ISelLowering.cpp - Expand f80, promote f32 to f64 for MSVC
diff --git a/llvm/include/llvm/CodeGen/BasicTTIImpl.h b/llvm/include/llvm/CodeGen/BasicTTIImpl.h
@@ -1998,6 +1998,9 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
     case Intrinsic::atan:
       ISD = ISD::FATAN;
       break;
+    case Intrinsic::atan2:
+      ISD = ISD::FATAN2;
+      break;
     case Intrinsic::sinh:
       ISD = ISD::FSINH;
       break;
diff --git a/llvm/include/llvm/CodeGen/ISDOpcodes.h b/llvm/include/llvm/CodeGen/ISDOpcodes.h
@@ -425,6 +425,7 @@ enum NodeType {
   STRICT_FASIN,
   STRICT_FACOS,
   STRICT_FATAN,
+  STRICT_FATAN2,
   STRICT_FSINH,
   STRICT_FCOSH,
   STRICT_FTANH,
@@ -994,6 +995,8 @@ enum NodeType {
   FPOWI,
   /// FLDEXP - ldexp, inspired by libm (op0 * 2**op1).
   FLDEXP,
+  /// FATAN2 - atan2, inspired by libm.
+  FATAN2,
 
   /// FFREXP - frexp, extract fractional and exponent component of a
   /// floating-point value. Returns the two components as separate return
diff --git a/llvm/include/llvm/IR/ConstrainedOps.def b/llvm/include/llvm/IR/ConstrainedOps.def
@@ -72,6 +72,7 @@ CMP_INSTRUCTION(FCmp,         2, 0, experimental_constrained_fcmps,      FSETCCS
 DAG_FUNCTION(acos,            1, 1, experimental_constrained_acos,       FACOS)
 DAG_FUNCTION(asin,            1, 1, experimental_constrained_asin,       FASIN)
 DAG_FUNCTION(atan,            1, 1, experimental_constrained_atan,       FATAN)
+DAG_FUNCTION(atan2,           2, 1, experimental_constrained_atan2,      FATAN2)
 DAG_FUNCTION(ceil,            1, 0, experimental_constrained_ceil,       FCEIL)
 DAG_FUNCTION(cos,             1, 1, experimental_constrained_cos,        FCOS)
 DAG_FUNCTION(cosh,            1, 1, experimental_constrained_cosh,       FCOSH)
diff --git a/llvm/include/llvm/IR/Intrinsics.td b/llvm/include/llvm/IR/Intrinsics.td
@@ -1235,6 +1235,11 @@ let IntrProperties = [IntrInaccessibleMemOnly, IntrWillReturn, IntrStrictFP] in
                                                     [ LLVMMatchType<0>,
                                                       llvm_metadata_ty,
                                                       llvm_metadata_ty ]>;
+  def int_experimental_constrained_atan2 : DefaultAttrsIntrinsic<[ llvm_anyfloat_ty ],
+                                                    [ LLVMMatchType<0>,
+                                                      LLVMMatchType<0>,
+                                                      llvm_metadata_ty,
+                                                      llvm_metadata_ty ]>;
   def int_experimental_constrained_sin  : DefaultAttrsIntrinsic<[ llvm_anyfloat_ty ],
                                                     [ LLVMMatchType<0>,
                                                       llvm_metadata_ty,
diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.def b/llvm/include/llvm/IR/RuntimeLibcalls.def
@@ -232,6 +232,11 @@ HANDLE_LIBCALL(ATAN_F64, "atan")
 HANDLE_LIBCALL(ATAN_F80, "atanl")
 HANDLE_LIBCALL(ATAN_F128,"atanl")
 HANDLE_LIBCALL(ATAN_PPCF128, "atanl")
+HANDLE_LIBCALL(ATAN2_F32, "atan2f")
+HANDLE_LIBCALL(ATAN2_F64, "atan2")
+HANDLE_LIBCALL(ATAN2_F80, "atan2l")
+HANDLE_LIBCALL(ATAN2_F128,"atan2l")
+HANDLE_LIBCALL(ATAN2_PPCF128, "atan2l")
 HANDLE_LIBCALL(SINCOS_F32, nullptr)
 HANDLE_LIBCALL(SINCOS_F64, nullptr)
 HANDLE_LIBCALL(SINCOS_F80, nullptr)
diff --git a/llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td b/llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td
@@ -154,6 +154,7 @@ def : GINodeEquiv<G_FTAN, ftan>;
 def : GINodeEquiv<G_FACOS, facos>;
 def : GINodeEquiv<G_FASIN, fasin>;
 def : GINodeEquiv<G_FATAN, fatan>;
+def : GINodeEquiv<G_FATAN2, fatan2>;
 def : GINodeEquiv<G_FCOSH, fcosh>;
 def : GINodeEquiv<G_FSINH, fsinh>;
 def : GINodeEquiv<G_FTANH, ftanh>;
diff --git a/llvm/include/llvm/Target/TargetSelectionDAG.td b/llvm/include/llvm/Target/TargetSelectionDAG.td
@@ -534,6 +534,7 @@ def ftan       : SDNode<"ISD::FTAN"       , SDTFPUnaryOp>;
 def fasin      : SDNode<"ISD::FASIN"      , SDTFPUnaryOp>;
 def facos      : SDNode<"ISD::FACOS"      , SDTFPUnaryOp>;
 def fatan      : SDNode<"ISD::FATAN"      , SDTFPUnaryOp>;
+def fatan2     : SDNode<"ISD::FATAN2"     , SDTFPBinOp>;
 def fsinh      : SDNode<"ISD::FSINH"      , SDTFPUnaryOp>;
 def fcosh      : SDNode<"ISD::FCOSH"      , SDTFPUnaryOp>;
 def ftanh      : SDNode<"ISD::FTANH"      , SDTFPUnaryOp>;
@@ -602,6 +603,8 @@ def strict_facos      : SDNode<"ISD::STRICT_FACOS",
                                SDTFPUnaryOp, [SDNPHasChain]>;
 def strict_fatan      : SDNode<"ISD::STRICT_FATAN",
                                SDTFPUnaryOp, [SDNPHasChain]>;
+def strict_fatan2     : SDNode<"ISD::STRICT_FATAN2",
+                               SDTFPBinOp, [SDNPHasChain]>;
 def strict_fsinh      : SDNode<"ISD::STRICT_FSINH",
                                SDTFPUnaryOp, [SDNPHasChain]>;
 def strict_fcosh      : SDNode<"ISD::STRICT_FCOSH",
@@ -1588,6 +1591,9 @@ def any_facos      : PatFrags<(ops node:$src),
 def any_fatan      : PatFrags<(ops node:$src),
                               [(strict_fatan node:$src),
                                (fatan node:$src)]>;
+def any_fatan2      : PatFrags<(ops node:$src1, node:$src2),
+                              [(strict_fatan2 node:$src1, node:$src2),
+                               (fatan2 node:$src1, node:$src2)]>;
 def any_fsinh      : PatFrags<(ops node:$src),
                               [(strict_fsinh node:$src),
                                (fsinh node:$src)]>;
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -457,6 +457,8 @@ static RTLIB::Libcall getRTLibDesc(unsigned Opcode, unsigned Size) {
     RTLIBCASE(ACOS_F);
   case TargetOpcode::G_FATAN:
     RTLIBCASE(ATAN_F);
+  case TargetOpcode::G_FATAN2:
+    RTLIBCASE(ATAN2_F);
   case TargetOpcode::G_FSINH:
     RTLIBCASE(SINH_F);
   case TargetOpcode::G_FCOSH:
@@ -1202,6 +1204,7 @@ LegalizerHelper::libcall(MachineInstr &MI, LostDebugLocObserver &LocObserver) {
   case TargetOpcode::G_FACOS:
   case TargetOpcode::G_FASIN:
   case TargetOpcode::G_FATAN:
+  case TargetOpcode::G_FATAN2:
   case TargetOpcode::G_FCOSH:
   case TargetOpcode::G_FSINH:
   case TargetOpcode::G_FTANH:
@@ -3122,6 +3125,7 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
   case TargetOpcode::G_FACOS:
   case TargetOpcode::G_FASIN:
   case TargetOpcode::G_FATAN:
+  case TargetOpcode::G_FATAN2:
   case TargetOpcode::G_FCOSH:
   case TargetOpcode::G_FSINH:
   case TargetOpcode::G_FTANH:
diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -828,6 +828,7 @@ bool llvm::isKnownNeverNaN(Register Val, const MachineRegisterInfo &MRI,
   case TargetOpcode::G_FACOS:
   case TargetOpcode::G_FASIN:
   case TargetOpcode::G_FATAN:
+  case TargetOpcode::G_FATAN2:
   case TargetOpcode::G_FCOSH:
   case TargetOpcode::G_FSINH:
   case TargetOpcode::G_FTANH:
@@ -1715,6 +1716,7 @@ bool llvm::isPreISelGenericFloatingPointOpcode(unsigned Opc) {
   case TargetOpcode::G_FACOS:
   case TargetOpcode::G_FASIN:
   case TargetOpcode::G_FATAN:
+  case TargetOpcode::G_FATAN2:
   case TargetOpcode::G_FCOSH:
   case TargetOpcode::G_FSINH:
   case TargetOpcode::G_FTANH:
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -4600,6 +4600,11 @@ void SelectionDAGLegalize::ConvertNodeToLibcall(SDNode *Node) {
     ExpandFPLibCall(Node, RTLIB::ATAN_F32, RTLIB::ATAN_F64, RTLIB::ATAN_F80,
                     RTLIB::ATAN_F128, RTLIB::ATAN_PPCF128, Results);
     break;
+  case ISD::FATAN2:
+  case ISD::STRICT_FATAN2:
+    ExpandFPLibCall(Node, RTLIB::ATAN2_F32, RTLIB::ATAN2_F64, RTLIB::ATAN2_F80,
+                    RTLIB::ATAN2_F128, RTLIB::ATAN2_PPCF128, Results);
+    break;
   case ISD::FSINH:
   case ISD::STRICT_FSINH:
     ExpandFPLibCall(Node, RTLIB::SINH_F32, RTLIB::SINH_F64, RTLIB::SINH_F80,
@@ -5486,6 +5491,7 @@ void SelectionDAGLegalize::PromoteNode(SDNode *Node) {
   case ISD::FMINIMUMNUM:
   case ISD::FMAXIMUMNUM:
   case ISD::FPOW:
+  case ISD::FATAN2:
     Tmp1 = DAG.getNode(ISD::FP_EXTEND, dl, NVT, Node->getOperand(0));
     Tmp2 = DAG.getNode(ISD::FP_EXTEND, dl, NVT, Node->getOperand(1));
     Tmp3 = DAG.getNode(Node->getOpcode(), dl, NVT, Tmp1, Tmp2,
@@ -5502,6 +5508,7 @@ void SelectionDAGLegalize::PromoteNode(SDNode *Node) {
   case ISD::STRICT_FMAXNUM:
   case ISD::STRICT_FREM:
   case ISD::STRICT_FPOW:
+  case ISD::STRICT_FATAN2:
     Tmp1 = DAG.getNode(ISD::STRICT_FP_EXTEND, dl, {NVT, MVT::Other},
                        {Node->getOperand(0), Node->getOperand(1)});
     Tmp2 = DAG.getNode(ISD::STRICT_FP_EXTEND, dl, {NVT, MVT::Other},
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp
@@ -84,6 +84,8 @@ void DAGTypeLegalizer::SoftenFloatResult(SDNode *N, unsigned ResNo) {
     case ISD::FASIN:       R = SoftenFloatRes_FASIN(N); break;
     case ISD::STRICT_FATAN:
     case ISD::FATAN:       R = SoftenFloatRes_FATAN(N); break;
+    case ISD::STRICT_FATAN2:
+    case ISD::FATAN2:      R = SoftenFloatRes_FATAN2(N); break;
     case ISD::FCBRT:       R = SoftenFloatRes_FCBRT(N); break;
     case ISD::STRICT_FCEIL:
     case ISD::FCEIL:       R = SoftenFloatRes_FCEIL(N); break;
@@ -366,6 +368,13 @@ SDValue DAGTypeLegalizer::SoftenFloatRes_FATAN(SDNode *N) {
                       RTLIB::ATAN_F80, RTLIB::ATAN_F128, RTLIB::ATAN_PPCF128));
 }
 
+SDValue DAGTypeLegalizer::SoftenFloatRes_FATAN2(SDNode *N) {
+  return SoftenFloatRes_Binary(
+      N,
+      GetFPLibCall(N->getValueType(0), RTLIB::ATAN2_F32, RTLIB::ATAN2_F64,
+                   RTLIB::ATAN2_F80, RTLIB::ATAN2_F128, RTLIB::ATAN2_PPCF128));
+}
+
 SDValue DAGTypeLegalizer::SoftenFloatRes_FCBRT(SDNode *N) {
   return SoftenFloatRes_Unary(N, GetFPLibCall(N->getValueType(0),
                                            RTLIB::CBRT_F32,
@@ -1430,6 +1439,8 @@ void DAGTypeLegalizer::ExpandFloatResult(SDNode *N, unsigned ResNo) {
   case ISD::FASIN:      ExpandFloatRes_FASIN(N, Lo, Hi); break;
   case ISD::STRICT_FATAN:
   case ISD::FATAN:      ExpandFloatRes_FATAN(N, Lo, Hi); break;
+  case ISD::STRICT_FATAN2:
+  case ISD::FATAN2:     ExpandFloatRes_FATAN2(N, Lo, Hi); break;
   case ISD::FCBRT:      ExpandFloatRes_FCBRT(N, Lo, Hi); break;
   case ISD::STRICT_FCEIL:
   case ISD::FCEIL:      ExpandFloatRes_FCEIL(N, Lo, Hi); break;
@@ -1631,6 +1642,15 @@ void DAGTypeLegalizer::ExpandFloatRes_FATAN(SDNode *N, SDValue &Lo,
                        Lo, Hi);
 }
 
+void DAGTypeLegalizer::ExpandFloatRes_FATAN2(SDNode *N, SDValue &Lo,
+                                             SDValue &Hi) {
+  ExpandFloatRes_Binary(N,
+                        GetFPLibCall(N->getValueType(0), RTLIB::ATAN2_F32,
+                                     RTLIB::ATAN2_F64, RTLIB::ATAN2_F80,
+                                     RTLIB::ATAN2_F128, RTLIB::ATAN2_PPCF128),
+                        Lo, Hi);
+}
+
 void DAGTypeLegalizer::ExpandFloatRes_FCBRT(SDNode *N, SDValue &Lo,
                                             SDValue &Hi) {
   ExpandFloatRes_Unary(N, GetFPLibCall(N->getValueType(0), RTLIB::CBRT_F32,
@@ -2673,6 +2693,7 @@ void DAGTypeLegalizer::PromoteFloatResult(SDNode *N, unsigned ResNo) {
     case ISD::FMINNUM_IEEE:
     case ISD::FMUL:
     case ISD::FPOW:
+    case ISD::FATAN2:
     case ISD::FREM:
     case ISD::FSUB:       R = PromoteFloatRes_BinOp(N); break;
 
@@ -3115,6 +3136,7 @@ void DAGTypeLegalizer::SoftPromoteHalfResult(SDNode *N, unsigned ResNo) {
   case ISD::FMINNUM:
   case ISD::FMUL:
   case ISD::FPOW:
+  case ISD::FATAN2:
   case ISD::FREM:
   case ISD::FSUB:        R = SoftPromoteHalfRes_BinOp(N); break;
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
@@ -567,6 +567,7 @@ class LLVM_LIBRARY_VISIBILITY DAGTypeLegalizer {
   SDValue SoftenFloatRes_FACOS(SDNode *N);
   SDValue SoftenFloatRes_FASIN(SDNode *N);
   SDValue SoftenFloatRes_FATAN(SDNode *N);
+  SDValue SoftenFloatRes_FATAN2(SDNode *N);
   SDValue SoftenFloatRes_FMINNUM(SDNode *N);
   SDValue SoftenFloatRes_FMAXNUM(SDNode *N);
   SDValue SoftenFloatRes_FMINIMUMNUM(SDNode *N);
@@ -661,6 +662,7 @@ class LLVM_LIBRARY_VISIBILITY DAGTypeLegalizer {
   void ExpandFloatRes_FACOS     (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FASIN     (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FATAN     (SDNode *N, SDValue &Lo, SDValue &Hi);
+  void ExpandFloatRes_FATAN2    (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FMINNUM   (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FMAXNUM   (SDNode *N, SDValue &Lo, SDValue &Hi);
   void ExpandFloatRes_FMINIMUMNUM(SDNode *N, SDValue &Lo, SDValue &Hi);
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
@@ -410,6 +410,7 @@ SDValue VectorLegalizer::LegalizeOp(SDValue Op) {
   case ISD::FASIN:
   case ISD::FACOS:
   case ISD::FATAN:
+  case ISD::FATAN2:
   case ISD::FSINH:
   case ISD::FCOSH:
   case ISD::FTANH:
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -164,6 +164,7 @@ void DAGTypeLegalizer::ScalarizeVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::USHLSAT:
 
   case ISD::FPOW:
+  case ISD::FATAN2:
   case ISD::FREM:
   case ISD::FSUB:
   case ISD::MUL:
@@ -1293,6 +1294,7 @@ void DAGTypeLegalizer::SplitVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::UDIV: case ISD::VP_UDIV:
   case ISD::FDIV: case ISD::VP_FDIV:
   case ISD::FPOW:
+  case ISD::FATAN2:
   case ISD::AND: case ISD::VP_AND:
   case ISD::OR: case ISD::VP_OR:
   case ISD::XOR: case ISD::VP_XOR:
@@ -4581,6 +4583,7 @@ void DAGTypeLegalizer::WidenVectorResult(SDNode *N, unsigned ResNo) {
     break;
 
   case ISD::FPOW:
+  case ISD::FATAN2:
   case ISD::FREM:
     if (unrollExpandedOp())
       break;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5460,6 +5460,7 @@ bool SelectionDAG::isKnownNeverNaN(SDValue Op, bool SNaN, unsigned Depth) const
   case ISD::FASIN:
   case ISD::FACOS:
   case ISD::FATAN:
+  case ISD::FATAN2:
   case ISD::FSINH:
   case ISD::FCOSH:
   case ISD::FTANH:
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6866,6 +6866,12 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
                              getValue(I.getArgOperand(0)), Flags));
     return;
   }
+  case Intrinsic::atan2:
+    setValue(&I, DAG.getNode(ISD::FATAN2, sdl,
+                             getValue(I.getArgOperand(0)).getValueType(),
+                             getValue(I.getArgOperand(0)),
+                             getValue(I.getArgOperand(1)), Flags));
+    return;
   case Intrinsic::lround:
   case Intrinsic::llround:
   case Intrinsic::lrint:
@@ -9358,6 +9364,12 @@ void SelectionDAGBuilder::visitCall(const CallInst &I) {
         if (visitUnaryFloatCall(I, ISD::FATAN))
           return;
         break;
+      case LibFunc_atan2:
+      case LibFunc_atan2f:
+      case LibFunc_atan2l:
+        if (visitBinaryFloatCall(I, ISD::FATAN2))
+          return;
+        break;
       case LibFunc_sinh:
       case LibFunc_sinhf:
       case LibFunc_sinhl:
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -227,6 +227,8 @@ std::string SDNode::getOperationName(const SelectionDAG *G) const {
   case ISD::STRICT_FACOS:               return "strict_facos";
   case ISD::FATAN:                      return "fatan";
   case ISD::STRICT_FATAN:               return "strict_fatan";
+  case ISD::FATAN2:                     return "fatan2";
+  case ISD::STRICT_FATAN2:              return "strict_fatan2";
   case ISD::FSINH:                      return "fsinh";
   case ISD::STRICT_FSINH:               return "strict_fsinh";
   case ISD::FCOSH:                      return "fcosh";
diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -783,7 +783,7 @@ void TargetLoweringBase::initActions() {
            ISD::SIGN_EXTEND_VECTOR_INREG, ISD::ZERO_EXTEND_VECTOR_INREG,
            ISD::SPLAT_VECTOR, ISD::LRINT, ISD::LLRINT, ISD::LROUND,
            ISD::LLROUND, ISD::FTAN, ISD::FACOS, ISD::FASIN, ISD::FATAN,
-           ISD::FCOSH, ISD::FSINH, ISD::FTANH},
+           ISD::FCOSH, ISD::FSINH, ISD::FTANH, ISD::FATAN2},
           VT, Expand);
 
       // Constrained floating-point operations default to expand.
@@ -842,15 +842,16 @@ void TargetLoweringBase::initActions() {
                       ISD::FEXP,       ISD::FEXP2, ISD::FEXP10, ISD::FFLOOR,
                       ISD::FNEARBYINT, ISD::FCEIL, ISD::FRINT,  ISD::FTRUNC,
                       ISD::FROUNDEVEN, ISD::FTAN,  ISD::FACOS,  ISD::FASIN,
-                      ISD::FATAN,      ISD::FCOSH, ISD::FSINH,  ISD::FTANH},
+                      ISD::FATAN,      ISD::FCOSH, ISD::FSINH,  ISD::FTANH,
+                      ISD::FATAN2},
                      {MVT::f32, MVT::f64, MVT::f128}, Expand);
 
   // FIXME: Query RuntimeLibCalls to make the decision.
   setOperationAction({ISD::LRINT, ISD::LLRINT, ISD::LROUND, ISD::LLROUND},
                      {MVT::f32, MVT::f64, MVT::f128}, LibCall);
 
   setOperationAction({ISD::FTAN, ISD::FACOS, ISD::FASIN, ISD::FATAN, ISD::FCOSH,
-                      ISD::FSINH, ISD::FTANH},
+                      ISD::FSINH, ISD::FTANH, ISD::FATAN2},
                      MVT::f16, Promote);
   // Default ISD::TRAP to expand (which turns it into abort).
   setOperationAction(ISD::TRAP, MVT::Other, Expand);
diff --git a/llvm/lib/IR/RuntimeLibcalls.cpp b/llvm/lib/IR/RuntimeLibcalls.cpp
@@ -49,6 +49,7 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT) {
     setLibcallName(RTLIB::ASIN_F128, "asinf128");
     setLibcallName(RTLIB::ACOS_F128, "acosf128");
     setLibcallName(RTLIB::ATAN_F128, "atanf128");
+    setLibcallName(RTLIB::ATAN2_F128, "atan2f128");
     setLibcallName(RTLIB::SINH_F128, "sinhf128");
     setLibcallName(RTLIB::COSH_F128, "coshf128");
     setLibcallName(RTLIB::TANH_F128, "tanhf128");
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -858,6 +858,7 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
     setOperationAction(ISD::FASIN  , MVT::f80, Expand);
     setOperationAction(ISD::FACOS  , MVT::f80, Expand);
     setOperationAction(ISD::FATAN  , MVT::f80, Expand);
+    setOperationAction(ISD::FATAN2 , MVT::f80, Expand);
     setOperationAction(ISD::FSINH  , MVT::f80, Expand);
     setOperationAction(ISD::FCOSH  , MVT::f80, Expand);
     setOperationAction(ISD::FTANH  , MVT::f80, Expand);
@@ -2562,6 +2563,7 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
          {ISD::FACOS,  ISD::STRICT_FACOS,
           ISD::FASIN,  ISD::STRICT_FASIN,
           ISD::FATAN,  ISD::STRICT_FATAN,
+          ISD::FATAN2, ISD::STRICT_FATAN2,
           ISD::FCEIL,  ISD::STRICT_FCEIL,
           ISD::FCOS,   ISD::STRICT_FCOS,
           ISD::FCOSH,  ISD::STRICT_FCOSH,
diff --git a/llvm/test/Assembler/fp-intrinsics-attr.ll b/llvm/test/Assembler/fp-intrinsics-attr.ll
@@ -105,6 +105,11 @@ define void @func(double %a, double %b, double %c, i32 %i) strictfp {
                                                metadata !"round.dynamic",
                                                metadata !"fpexcept.strict")
 
+  %atan2 = call double @llvm.experimental.constrained.atan2.f64(
+                                               double %a, double %b,
+                                               metadata !"round.dynamic",
+                                               metadata !"fpexcept.strict")
+
   %cosh = call double @llvm.experimental.constrained.cosh.f64(
                                                double %a,
                                                metadata !"round.dynamic",
@@ -291,6 +296,9 @@ declare double @llvm.experimental.constrained.acos.f64(double, metadata, metadat
 declare double @llvm.experimental.constrained.atan.f64(double, metadata, metadata)
 ; CHECK: @llvm.experimental.constrained.atan.f64({{.*}}) #[[ATTR1]]
 
+declare double @llvm.experimental.constrained.atan2.f64(double, double, metadata, metadata)
+; CHECK: @llvm.experimental.constrained.atan2.f64({{.*}}) #[[ATTR1]]
+
 declare double @llvm.experimental.constrained.sinh.f64(double, metadata, metadata)
 ; CHECK: @llvm.experimental.constrained.sinh.f64({{.*}}) #[[ATTR1]]
 
diff --git a/llvm/test/CodeGen/X86/fp-intrinsics.ll b/llvm/test/CodeGen/X86/fp-intrinsics.ll
diff --git a/llvm/test/CodeGen/X86/fp128-libcalls-strict.ll b/llvm/test/CodeGen/X86/fp128-libcalls-strict.ll
diff --git a/llvm/test/CodeGen/X86/fp80-strict-libcalls.ll b/llvm/test/CodeGen/X86/fp80-strict-libcalls.ll
diff --git a/llvm/test/CodeGen/X86/llvm.atan2.ll b/llvm/test/CodeGen/X86/llvm.atan2.ll
diff --git a/llvm/test/CodeGen/X86/vector-constrained-fp-intrinsics.ll b/llvm/test/CodeGen/X86/vector-constrained-fp-intrinsics.ll
diff --git a/llvm/test/Feature/fp-intrinsics.ll b/llvm/test/Feature/fp-intrinsics.ll
