1 //===-- llvm/CodeGen/GlobalISel/CallLowering.h - Call lowering --*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 /// 10 /// \file 11 /// This file describes how to lower LLVM calls to machine code calls. 12 /// 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_CODEGEN_GLOBALISEL_CALLLOWERING_H 16 #define LLVM_CODEGEN_GLOBALISEL_CALLLOWERING_H 17 18 #include "llvm/ADT/SmallVector.h" 19 #include "llvm/CodeGen/CallingConvLower.h" 20 #include "llvm/CodeGen/ValueTypes.h" 21 #include "llvm/IR/Function.h" 22 #include "llvm/Target/TargetCallingConv.h" 23 24 namespace llvm { 25 // Forward declarations. 26 class MachineIRBuilder; 27 class MachineOperand; 28 class TargetLowering; 29 class Value; 30 31 class CallLowering { 32 const TargetLowering *TLI; 33 public: 34 struct ArgInfo { 35 unsigned Reg; 36 Type *Ty; 37 ISD::ArgFlagsTy Flags; 38 bool IsFixed; 39 40 ArgInfo(unsigned Reg, Type *Ty, ISD::ArgFlagsTy Flags = ISD::ArgFlagsTy{}, 41 bool IsFixed = true) 42 : Reg(Reg), Ty(Ty), Flags(Flags), IsFixed(IsFixed) {} 43 }; 44 45 /// Argument handling is mostly uniform between the four places that 46 /// make these decisions: function formal arguments, call 47 /// instruction args, call instruction returns and function 48 /// returns. However, once a decision has been made on where an 49 /// arugment should go, exactly what happens can vary slightly. This 50 /// class abstracts the differences. 51 struct ValueHandler { 52 /// Materialize a VReg containing the address of the specified 53 /// stack-based object. This is either based on a FrameIndex or 54 /// direct SP manipulation, depending on the context. \p MPO 55 /// should be initialized to an appropriate description of the 56 /// address created. 57 virtual unsigned getStackAddress(uint64_t Size, int64_t Offset, 58 MachinePointerInfo &MPO) = 0; 59 60 /// The specified value has been assigned to a physical register, 61 /// handle the appropriate COPY (either to or from) and mark any 62 /// relevant uses/defines as needed. 63 virtual void assignValueToReg(unsigned ValVReg, unsigned PhysReg, 64 CCValAssign &VA) = 0; 65 66 /// The specified value has been assigned to a stack 67 /// location. Load or store it there, with appropriate extension 68 /// if necessary. 69 virtual void assignValueToAddress(unsigned ValVReg, unsigned Addr, 70 uint64_t Size, MachinePointerInfo &MPO, 71 CCValAssign &VA) = 0; 72 73 /// Handle custom values, which may be passed into one or more of \p VAs. 74 /// \return The number of \p VAs that have been assigned after the first 75 /// one, and which should therefore be skipped from further 76 /// processing. 77 virtual unsigned assignCustomValue(const ArgInfo &Arg, 78 ArrayRef<CCValAssign> VAs) { 79 // This is not a pure virtual method because not all targets need to worry 80 // about custom values. 81 llvm_unreachable("Custom values not supported"); 82 } 83 84 unsigned extendRegister(unsigned ValReg, CCValAssign &VA); 85 86 virtual bool assignArg(unsigned ValNo, MVT ValVT, MVT LocVT, 87 CCValAssign::LocInfo LocInfo, const ArgInfo &Info, 88 CCState &State) { 89 return AssignFn(ValNo, ValVT, LocVT, LocInfo, Info.Flags, State); 90 } 91 92 ValueHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI, 93 CCAssignFn *AssignFn) 94 : MIRBuilder(MIRBuilder), MRI(MRI), AssignFn(AssignFn) {} 95 96 virtual ~ValueHandler() {} 97 98 MachineIRBuilder &MIRBuilder; 99 MachineRegisterInfo &MRI; 100 CCAssignFn *AssignFn; 101 }; 102 103 protected: 104 /// Getter for generic TargetLowering class. 105 const TargetLowering *getTLI() const { 106 return TLI; 107 } 108 109 /// Getter for target specific TargetLowering class. 110 template <class XXXTargetLowering> 111 const XXXTargetLowering *getTLI() const { 112 return static_cast<const XXXTargetLowering *>(TLI); 113 } 114 115 116 template <typename FuncInfoTy> 117 void setArgFlags(ArgInfo &Arg, unsigned OpNum, const DataLayout &DL, 118 const FuncInfoTy &FuncInfo) const; 119 120 /// Invoke Handler::assignArg on each of the given \p Args and then use 121 /// \p Callback to move them to the assigned locations. 122 /// 123 /// \return True if everything has succeeded, false otherwise. 124 bool handleAssignments(MachineIRBuilder &MIRBuilder, ArrayRef<ArgInfo> Args, 125 ValueHandler &Callback) const; 126 127 public: 128 CallLowering(const TargetLowering *TLI) : TLI(TLI) {} 129 virtual ~CallLowering() {} 130 131 /// This hook must be implemented to lower outgoing return values, described 132 /// by \p Val, into the specified virtual register \p VReg. 133 /// This hook is used by GlobalISel. 134 /// 135 /// \return True if the lowering succeeds, false otherwise. 136 virtual bool lowerReturn(MachineIRBuilder &MIRBuilder, 137 const Value *Val, unsigned VReg) const { 138 return false; 139 } 140 141 /// This hook must be implemented to lower the incoming (formal) 142 /// arguments, described by \p Args, for GlobalISel. Each argument 143 /// must end up in the related virtual register described by VRegs. 144 /// In other words, the first argument should end up in VRegs[0], 145 /// the second in VRegs[1], and so on. 146 /// \p MIRBuilder is set to the proper insertion for the argument 147 /// lowering. 148 /// 149 /// \return True if the lowering succeeded, false otherwise. 150 virtual bool lowerFormalArguments(MachineIRBuilder &MIRBuilder, 151 const Function &F, 152 ArrayRef<unsigned> VRegs) const { 153 return false; 154 } 155 156 /// This hook must be implemented to lower the given call instruction, 157 /// including argument and return value marshalling. 158 /// 159 /// \p CallConv is the calling convention to be used for the call. 160 /// 161 /// \p Callee is the destination of the call. It should be either a register, 162 /// globaladdress, or externalsymbol. 163 /// 164 /// \p ResTy is the type returned by the function 165 /// 166 /// \p ResReg is the generic virtual register that the returned 167 /// value should be lowered into. 168 /// 169 /// \p ArgTys is a list of the types each member of \p ArgRegs has; used by 170 /// the target to decide which register/stack slot should be allocated. 171 /// 172 /// \p ArgRegs is a list of virtual registers containing each argument that 173 /// needs to be passed. 174 /// 175 /// \return true if the lowering succeeded, false otherwise. 176 virtual bool lowerCall(MachineIRBuilder &MIRBuilder, CallingConv::ID CallConv, 177 const MachineOperand &Callee, const ArgInfo &OrigRet, 178 ArrayRef<ArgInfo> OrigArgs) const { 179 return false; 180 } 181 182 /// Lower the given call instruction, including argument and return value 183 /// marshalling. 184 /// 185 /// \p CI is the call/invoke instruction. 186 /// 187 /// \p ResReg is a register where the call's return value should be stored (or 188 /// 0 if there is no return value). 189 /// 190 /// \p ArgRegs is a list of virtual registers containing each argument that 191 /// needs to be passed. 192 /// 193 /// \p GetCalleeReg is a callback to materialize a register for the callee if 194 /// the target determines it cannot jump to the destination based purely on \p 195 /// CI. This might be because \p CI is indirect, or because of the limited 196 /// range of an immediate jump. 197 /// 198 /// \return true if the lowering succeeded, false otherwise. 199 bool lowerCall(MachineIRBuilder &MIRBuilder, ImmutableCallSite CS, 200 unsigned ResReg, ArrayRef<unsigned> ArgRegs, 201 std::function<unsigned()> GetCalleeReg) const; 202 }; 203 } // End namespace llvm. 204 205 #endif 206
