1 //===- llvm/CodeGen/GlobalISel/CallLowering.h - Call lowering ---*- C++ -*-===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
10 /// This file describes how to lower LLVM calls to machine code calls.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CODEGEN_GLOBALISEL_CALLLOWERING_H
15 #define LLVM_CODEGEN_GLOBALISEL_CALLLOWERING_H
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/CodeGen/CallingConvLower.h"
20 #include "llvm/CodeGen/TargetCallingConv.h"
21 #include "llvm/IR/CallSite.h"
22 #include "llvm/IR/CallingConv.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/MachineValueType.h"
33 class MachineIRBuilder;
35 struct MachinePointerInfo;
36 class MachineRegisterInfo;
42 const TargetLowering *TLI;
44 virtual void anchor();
47 SmallVector<Register, 4> Regs;
49 ISD::ArgFlagsTy Flags;
52 ArgInfo(ArrayRef<Register> Regs, Type *Ty,
53 ISD::ArgFlagsTy Flags = ISD::ArgFlagsTy{}, bool IsFixed = true)
54 : Regs(Regs.begin(), Regs.end()), Ty(Ty), Flags(Flags),
56 // FIXME: We should have just one way of saying "no register".
57 assert((Ty->isVoidTy() == (Regs.empty() || Regs[0] == 0)) &&
58 "only void types should have no register");
62 /// Argument handling is mostly uniform between the four places that
63 /// make these decisions: function formal arguments, call
64 /// instruction args, call instruction returns and function
65 /// returns. However, once a decision has been made on where an
66 /// arugment should go, exactly what happens can vary slightly. This
67 /// class abstracts the differences.
69 ValueHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
71 : MIRBuilder(MIRBuilder), MRI(MRI), AssignFn(AssignFn) {}
73 virtual ~ValueHandler() = default;
75 /// Returns true if the handler is dealing with formal arguments,
76 /// not with return values etc.
77 virtual bool isArgumentHandler() const { return false; }
79 /// Materialize a VReg containing the address of the specified
80 /// stack-based object. This is either based on a FrameIndex or
81 /// direct SP manipulation, depending on the context. \p MPO
82 /// should be initialized to an appropriate description of the
84 virtual Register getStackAddress(uint64_t Size, int64_t Offset,
85 MachinePointerInfo &MPO) = 0;
87 /// The specified value has been assigned to a physical register,
88 /// handle the appropriate COPY (either to or from) and mark any
89 /// relevant uses/defines as needed.
90 virtual void assignValueToReg(Register ValVReg, Register PhysReg,
93 /// The specified value has been assigned to a stack
94 /// location. Load or store it there, with appropriate extension
96 virtual void assignValueToAddress(Register ValVReg, Register Addr,
97 uint64_t Size, MachinePointerInfo &MPO,
100 /// Handle custom values, which may be passed into one or more of \p VAs.
101 /// \return The number of \p VAs that have been assigned after the first
102 /// one, and which should therefore be skipped from further
104 virtual unsigned assignCustomValue(const ArgInfo &Arg,
105 ArrayRef<CCValAssign> VAs) {
106 // This is not a pure virtual method because not all targets need to worry
107 // about custom values.
108 llvm_unreachable("Custom values not supported");
111 Register extendRegister(Register ValReg, CCValAssign &VA);
113 virtual bool assignArg(unsigned ValNo, MVT ValVT, MVT LocVT,
114 CCValAssign::LocInfo LocInfo, const ArgInfo &Info,
116 return AssignFn(ValNo, ValVT, LocVT, LocInfo, Info.Flags, State);
119 MachineIRBuilder &MIRBuilder;
120 MachineRegisterInfo &MRI;
121 CCAssignFn *AssignFn;
124 virtual void anchor();
128 /// Getter for generic TargetLowering class.
129 const TargetLowering *getTLI() const {
133 /// Getter for target specific TargetLowering class.
134 template <class XXXTargetLowering>
135 const XXXTargetLowering *getTLI() const {
136 return static_cast<const XXXTargetLowering *>(TLI);
139 template <typename FuncInfoTy>
140 void setArgFlags(ArgInfo &Arg, unsigned OpIdx, const DataLayout &DL,
141 const FuncInfoTy &FuncInfo) const;
143 /// Generate instructions for packing \p SrcRegs into one big register
144 /// corresponding to the aggregate type \p PackedTy.
146 /// \param SrcRegs should contain one virtual register for each base type in
147 /// \p PackedTy, as returned by computeValueLLTs.
149 /// \return The packed register.
150 Register packRegs(ArrayRef<Register> SrcRegs, Type *PackedTy,
151 MachineIRBuilder &MIRBuilder) const;
153 /// Generate instructions for unpacking \p SrcReg into the \p DstRegs
154 /// corresponding to the aggregate type \p PackedTy.
156 /// \param DstRegs should contain one virtual register for each base type in
157 /// \p PackedTy, as returned by computeValueLLTs.
158 void unpackRegs(ArrayRef<Register> DstRegs, Register SrcReg, Type *PackedTy,
159 MachineIRBuilder &MIRBuilder) const;
161 /// Invoke Handler::assignArg on each of the given \p Args and then use
162 /// \p Callback to move them to the assigned locations.
164 /// \return True if everything has succeeded, false otherwise.
165 bool handleAssignments(MachineIRBuilder &MIRBuilder, ArrayRef<ArgInfo> Args,
166 ValueHandler &Handler) const;
167 bool handleAssignments(CCState &CCState,
168 SmallVectorImpl<CCValAssign> &ArgLocs,
169 MachineIRBuilder &MIRBuilder, ArrayRef<ArgInfo> Args,
170 ValueHandler &Handler) const;
172 CallLowering(const TargetLowering *TLI) : TLI(TLI) {}
173 virtual ~CallLowering() = default;
175 /// \return true if the target is capable of handling swifterror values that
176 /// have been promoted to a specified register. The extended versions of
177 /// lowerReturn and lowerCall should be implemented.
178 virtual bool supportSwiftError() const {
182 /// This hook must be implemented to lower outgoing return values, described
183 /// by \p Val, into the specified virtual registers \p VRegs.
184 /// This hook is used by GlobalISel.
186 /// \p SwiftErrorVReg is non-zero if the function has a swifterror parameter
187 /// that needs to be implicitly returned.
189 /// \return True if the lowering succeeds, false otherwise.
190 virtual bool lowerReturn(MachineIRBuilder &MIRBuilder, const Value *Val,
191 ArrayRef<Register> VRegs,
192 Register SwiftErrorVReg) const {
193 if (!supportSwiftError()) {
194 assert(SwiftErrorVReg == 0 && "attempt to use unsupported swifterror");
195 return lowerReturn(MIRBuilder, Val, VRegs);
200 /// This hook behaves as the extended lowerReturn function, but for targets
201 /// that do not support swifterror value promotion.
202 virtual bool lowerReturn(MachineIRBuilder &MIRBuilder, const Value *Val,
203 ArrayRef<Register> VRegs) const {
207 /// This hook must be implemented to lower the incoming (formal)
208 /// arguments, described by \p VRegs, for GlobalISel. Each argument
209 /// must end up in the related virtual registers described by \p VRegs.
210 /// In other words, the first argument should end up in \c VRegs[0],
211 /// the second in \c VRegs[1], and so on. For each argument, there will be one
212 /// register for each non-aggregate type, as returned by \c computeValueLLTs.
213 /// \p MIRBuilder is set to the proper insertion for the argument
216 /// \return True if the lowering succeeded, false otherwise.
217 virtual bool lowerFormalArguments(MachineIRBuilder &MIRBuilder,
219 ArrayRef<ArrayRef<Register>> VRegs) const {
223 /// This hook must be implemented to lower the given call instruction,
224 /// including argument and return value marshalling.
226 /// \p CallConv is the calling convention to be used for the call.
228 /// \p Callee is the destination of the call. It should be either a register,
229 /// globaladdress, or externalsymbol.
231 /// \p OrigRet is a descriptor for the return type of the function.
233 /// \p OrigArgs is a list of descriptors of the arguments passed to the
236 /// \p SwiftErrorVReg is non-zero if the call has a swifterror inout
237 /// parameter, and contains the vreg that the swifterror should be copied into
240 /// \return true if the lowering succeeded, false otherwise.
241 virtual bool lowerCall(MachineIRBuilder &MIRBuilder, CallingConv::ID CallConv,
242 const MachineOperand &Callee, const ArgInfo &OrigRet,
243 ArrayRef<ArgInfo> OrigArgs,
244 Register SwiftErrorVReg) const {
245 if (!supportSwiftError()) {
246 assert(SwiftErrorVReg == 0 && "trying to use unsupported swifterror");
247 return lowerCall(MIRBuilder, CallConv, Callee, OrigRet, OrigArgs);
252 /// This hook behaves as the extended lowerCall function, but for targets that
253 /// do not support swifterror value promotion.
254 virtual bool lowerCall(MachineIRBuilder &MIRBuilder, CallingConv::ID CallConv,
255 const MachineOperand &Callee, const ArgInfo &OrigRet,
256 ArrayRef<ArgInfo> OrigArgs) const {
260 /// Lower the given call instruction, including argument and return value
263 /// \p CI is the call/invoke instruction.
265 /// \p ResRegs are the registers where the call's return value should be
266 /// stored (or 0 if there is no return value). There will be one register for
267 /// each non-aggregate type, as returned by \c computeValueLLTs.
269 /// \p ArgRegs is a list of lists of virtual registers containing each
270 /// argument that needs to be passed (argument \c i should be placed in \c
271 /// ArgRegs[i]). For each argument, there will be one register for each
272 /// non-aggregate type, as returned by \c computeValueLLTs.
274 /// \p SwiftErrorVReg is non-zero if the call has a swifterror inout
275 /// parameter, and contains the vreg that the swifterror should be copied into
278 /// \p GetCalleeReg is a callback to materialize a register for the callee if
279 /// the target determines it cannot jump to the destination based purely on \p
280 /// CI. This might be because \p CI is indirect, or because of the limited
281 /// range of an immediate jump.
283 /// \return true if the lowering succeeded, false otherwise.
284 bool lowerCall(MachineIRBuilder &MIRBuilder, ImmutableCallSite CS,
285 ArrayRef<Register> ResRegs,
286 ArrayRef<ArrayRef<Register>> ArgRegs, Register SwiftErrorVReg,
287 std::function<unsigned()> GetCalleeReg) const;
290 } // end namespace llvm
292 #endif // LLVM_CODEGEN_GLOBALISEL_CALLLOWERING_H