1 //==-- llvm/CodeGen/GlobalISel/Utils.h ---------------------------*- 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 //===----------------------------------------------------------------------===//
9 /// \file This file declares the API of helper functions used throughout the
10 /// GlobalISel pipeline.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CODEGEN_GLOBALISEL_UTILS_H
15 #define LLVM_CODEGEN_GLOBALISEL_UTILS_H
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/CodeGen/Register.h"
19 #include "llvm/Support/Alignment.h"
20 #include "llvm/Support/LowLevelTypeImpl.h"
21 #include "llvm/Support/MachineValueType.h"
26 class MachineFunction;
29 class MachineOptimizationRemarkEmitter;
30 class MachineOptimizationRemarkMissed;
31 struct MachinePointerInfo;
32 class MachineRegisterInfo;
34 class RegisterBankInfo;
35 class TargetInstrInfo;
36 class TargetPassConfig;
37 class TargetRegisterInfo;
38 class TargetRegisterClass;
43 /// Try to constrain Reg to the specified register class. If this fails,
44 /// create a new virtual register in the correct class.
46 /// \return The virtual register constrained to the right register class.
47 Register constrainRegToClass(MachineRegisterInfo &MRI,
48 const TargetInstrInfo &TII,
49 const RegisterBankInfo &RBI, Register Reg,
50 const TargetRegisterClass &RegClass);
52 /// Constrain the Register operand OpIdx, so that it is now constrained to the
53 /// TargetRegisterClass passed as an argument (RegClass).
54 /// If this fails, create a new virtual register in the correct class and
55 /// insert a COPY before \p InsertPt if it is a use or after if it is a
56 /// definition. The debug location of \p InsertPt is used for the new copy.
58 /// \return The virtual register constrained to the right register class.
59 Register constrainOperandRegClass(const MachineFunction &MF,
60 const TargetRegisterInfo &TRI,
61 MachineRegisterInfo &MRI,
62 const TargetInstrInfo &TII,
63 const RegisterBankInfo &RBI,
64 MachineInstr &InsertPt,
65 const TargetRegisterClass &RegClass,
66 const MachineOperand &RegMO);
68 /// Try to constrain Reg so that it is usable by argument OpIdx of the
69 /// provided MCInstrDesc \p II. If this fails, create a new virtual
70 /// register in the correct class and insert a COPY before \p InsertPt
71 /// if it is a use or after if it is a definition.
72 /// This is equivalent to constrainOperandRegClass(..., RegClass, ...)
73 /// with RegClass obtained from the MCInstrDesc. The debug location of \p
74 /// InsertPt is used for the new copy.
76 /// \return The virtual register constrained to the right register class.
77 Register constrainOperandRegClass(const MachineFunction &MF,
78 const TargetRegisterInfo &TRI,
79 MachineRegisterInfo &MRI,
80 const TargetInstrInfo &TII,
81 const RegisterBankInfo &RBI,
82 MachineInstr &InsertPt, const MCInstrDesc &II,
83 const MachineOperand &RegMO, unsigned OpIdx);
85 /// Mutate the newly-selected instruction \p I to constrain its (possibly
86 /// generic) virtual register operands to the instruction's register class.
87 /// This could involve inserting COPYs before (for uses) or after (for defs).
88 /// This requires the number of operands to match the instruction description.
89 /// \returns whether operand regclass constraining succeeded.
91 // FIXME: Not all instructions have the same number of operands. We should
92 // probably expose a constrain helper per operand and let the target selector
93 // constrain individual registers, like fast-isel.
94 bool constrainSelectedInstRegOperands(MachineInstr &I,
95 const TargetInstrInfo &TII,
96 const TargetRegisterInfo &TRI,
97 const RegisterBankInfo &RBI);
99 /// Check if DstReg can be replaced with SrcReg depending on the register
101 bool canReplaceReg(Register DstReg, Register SrcReg, MachineRegisterInfo &MRI);
103 /// Check whether an instruction \p MI is dead: it only defines dead virtual
104 /// registers, and doesn't have other side effects.
105 bool isTriviallyDead(const MachineInstr &MI, const MachineRegisterInfo &MRI);
107 /// Report an ISel error as a missed optimization remark to the LLVMContext's
108 /// diagnostic stream. Set the FailedISel MachineFunction property.
109 void reportGISelFailure(MachineFunction &MF, const TargetPassConfig &TPC,
110 MachineOptimizationRemarkEmitter &MORE,
111 MachineOptimizationRemarkMissed &R);
113 void reportGISelFailure(MachineFunction &MF, const TargetPassConfig &TPC,
114 MachineOptimizationRemarkEmitter &MORE,
115 const char *PassName, StringRef Msg,
116 const MachineInstr &MI);
118 /// Report an ISel warning as a missed optimization remark to the LLVMContext's
119 /// diagnostic stream.
120 void reportGISelWarning(MachineFunction &MF, const TargetPassConfig &TPC,
121 MachineOptimizationRemarkEmitter &MORE,
122 MachineOptimizationRemarkMissed &R);
124 /// If \p VReg is defined by a G_CONSTANT fits in int64_t
126 Optional<int64_t> getConstantVRegVal(Register VReg,
127 const MachineRegisterInfo &MRI);
128 /// Simple struct used to hold a constant integer value and a virtual
130 struct ValueAndVReg {
134 /// If \p VReg is defined by a statically evaluable chain of
135 /// instructions rooted on a G_F/CONSTANT (\p LookThroughInstrs == true)
136 /// and that constant fits in int64_t, returns its value as well as the
137 /// virtual register defined by this G_F/CONSTANT.
138 /// When \p LookThroughInstrs == false this function behaves like
139 /// getConstantVRegVal.
140 /// When \p HandleFConstants == false the function bails on G_FCONSTANTs.
141 Optional<ValueAndVReg>
142 getConstantVRegValWithLookThrough(Register VReg, const MachineRegisterInfo &MRI,
143 bool LookThroughInstrs = true,
144 bool HandleFConstants = true);
145 const ConstantFP* getConstantFPVRegVal(Register VReg,
146 const MachineRegisterInfo &MRI);
148 /// See if Reg is defined by an single def instruction that is
149 /// Opcode. Also try to do trivial folding if it's a COPY with
150 /// same types. Returns null otherwise.
151 MachineInstr *getOpcodeDef(unsigned Opcode, Register Reg,
152 const MachineRegisterInfo &MRI);
154 /// Find the def instruction for \p Reg, folding away any trivial copies. Note
155 /// it may still return a COPY, if it changes the type. May return nullptr if \p
156 /// Reg is not a generic virtual register.
157 MachineInstr *getDefIgnoringCopies(Register Reg,
158 const MachineRegisterInfo &MRI);
160 /// Find the source register for \p Reg, folding away any trivial copies. It
161 /// will be an output register of the instruction that getDefIgnoringCopies
162 /// returns. May return an invalid register if \p Reg is not a generic virtual
164 Register getSrcRegIgnoringCopies(Register Reg,
165 const MachineRegisterInfo &MRI);
167 /// Returns an APFloat from Val converted to the appropriate size.
168 APFloat getAPFloatFromSize(double Val, unsigned Size);
170 /// Modify analysis usage so it preserves passes required for the SelectionDAG
172 void getSelectionDAGFallbackAnalysisUsage(AnalysisUsage &AU);
174 Optional<APInt> ConstantFoldBinOp(unsigned Opcode, const Register Op1,
176 const MachineRegisterInfo &MRI);
178 Optional<APInt> ConstantFoldExtOp(unsigned Opcode, const Register Op1,
179 uint64_t Imm, const MachineRegisterInfo &MRI);
181 /// Returns true if \p Val can be assumed to never be a NaN. If \p SNaN is true,
182 /// this returns if \p Val can be assumed to never be a signaling NaN.
183 bool isKnownNeverNaN(Register Val, const MachineRegisterInfo &MRI,
186 /// Returns true if \p Val can be assumed to never be a signaling NaN.
187 inline bool isKnownNeverSNaN(Register Val, const MachineRegisterInfo &MRI) {
188 return isKnownNeverNaN(Val, MRI, true);
191 Align inferAlignFromPtrInfo(MachineFunction &MF, const MachinePointerInfo &MPO);
193 /// Return the least common multiple type of \p Ty0 and \p Ty1, by changing
194 /// the number of vector elements or scalar bitwidth. The intent is a
195 /// G_MERGE_VALUES can be constructed from \p Ty0 elements, and unmerged into
197 LLT getLCMType(LLT Ty0, LLT Ty1);
199 /// Return a type that is greatest common divisor of \p OrigTy and \p
200 /// TargetTy. This will either change the number of vector elements, or
201 /// bitwidth of scalars. The intent is the result type can be used as the
202 /// result of a G_UNMERGE_VALUES from \p OrigTy.
203 LLT getGCDType(LLT OrigTy, LLT TargetTy);
205 } // End namespace llvm.