1 //===- llvm/CodeGen/TargetSubtargetInfo.h - Target Information --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file describes the subtarget options of a Target machine.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CODEGEN_TARGETSUBTARGETINFO_H
15 #define LLVM_CODEGEN_TARGETSUBTARGETINFO_H
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/CodeGen/PBQPRAConstraint.h"
21 #include "llvm/CodeGen/ScheduleDAGMutation.h"
22 #include "llvm/CodeGen/SchedulerRegistry.h"
23 #include "llvm/MC/MCSubtargetInfo.h"
24 #include "llvm/Support/CodeGen.h"
32 class InstrItineraryData;
34 class InstructionSelector;
37 struct MachineSchedPolicy;
38 struct MCReadAdvanceEntry;
39 struct MCWriteLatencyEntry;
40 struct MCWriteProcResEntry;
41 class RegisterBankInfo;
43 class SelectionDAGTargetInfo;
44 struct SubtargetFeatureKV;
45 struct SubtargetInfoKV;
47 class TargetFrameLowering;
48 class TargetInstrInfo;
50 class TargetRegisterClass;
51 class TargetRegisterInfo;
52 class TargetSchedModel;
55 //===----------------------------------------------------------------------===//
57 /// TargetSubtargetInfo - Generic base class for all target subtargets. All
58 /// Target-specific options that control code generation and printing should
59 /// be exposed through a TargetSubtargetInfo-derived class.
61 class TargetSubtargetInfo : public MCSubtargetInfo {
62 protected: // Can only create subclasses...
63 TargetSubtargetInfo(const Triple &TT, StringRef CPU, StringRef FS,
64 ArrayRef<SubtargetFeatureKV> PF,
65 ArrayRef<SubtargetFeatureKV> PD,
66 const SubtargetInfoKV *ProcSched,
67 const MCWriteProcResEntry *WPR,
68 const MCWriteLatencyEntry *WL,
69 const MCReadAdvanceEntry *RA, const InstrStage *IS,
70 const unsigned *OC, const unsigned *FP);
73 // AntiDepBreakMode - Type of anti-dependence breaking that should
74 // be performed before post-RA scheduling.
75 using AntiDepBreakMode = enum { ANTIDEP_NONE, ANTIDEP_CRITICAL, ANTIDEP_ALL };
76 using RegClassVector = SmallVectorImpl<const TargetRegisterClass *>;
78 TargetSubtargetInfo() = delete;
79 TargetSubtargetInfo(const TargetSubtargetInfo &) = delete;
80 TargetSubtargetInfo &operator=(const TargetSubtargetInfo &) = delete;
81 ~TargetSubtargetInfo() override;
83 virtual bool isXRaySupported() const { return false; }
85 // Interfaces to the major aspects of target machine information:
87 // -- Instruction opcode and operand information
88 // -- Pipelines and scheduling information
89 // -- Stack frame information
90 // -- Selection DAG lowering information
91 // -- Call lowering information
93 // N.B. These objects may change during compilation. It's not safe to cache
94 // them between functions.
95 virtual const TargetInstrInfo *getInstrInfo() const { return nullptr; }
96 virtual const TargetFrameLowering *getFrameLowering() const {
99 virtual const TargetLowering *getTargetLowering() const { return nullptr; }
100 virtual const SelectionDAGTargetInfo *getSelectionDAGInfo() const {
103 virtual const CallLowering *getCallLowering() const { return nullptr; }
105 // FIXME: This lets targets specialize the selector by subtarget (which lets
106 // us do things like a dedicated avx512 selector). However, we might want
107 // to also specialize selectors by MachineFunction, which would let us be
108 // aware of optsize/optnone and such.
109 virtual const InstructionSelector *getInstructionSelector() const {
113 virtual unsigned getHwMode() const { return 0; }
115 /// Target can subclass this hook to select a different DAG scheduler.
116 virtual RegisterScheduler::FunctionPassCtor
117 getDAGScheduler(CodeGenOpt::Level) const {
121 virtual const LegalizerInfo *getLegalizerInfo() const { return nullptr; }
123 /// getRegisterInfo - If register information is available, return it. If
124 /// not, return null.
125 virtual const TargetRegisterInfo *getRegisterInfo() const { return nullptr; }
127 /// If the information for the register banks is available, return it.
128 /// Otherwise return nullptr.
129 virtual const RegisterBankInfo *getRegBankInfo() const { return nullptr; }
131 /// getInstrItineraryData - Returns instruction itinerary data for the target
132 /// or specific subtarget.
133 virtual const InstrItineraryData *getInstrItineraryData() const {
137 /// Resolve a SchedClass at runtime, where SchedClass identifies an
138 /// MCSchedClassDesc with the isVariant property. This may return the ID of
139 /// another variant SchedClass, but repeated invocation must quickly terminate
140 /// in a nonvariant SchedClass.
141 virtual unsigned resolveSchedClass(unsigned SchedClass,
142 const MachineInstr *MI,
143 const TargetSchedModel *SchedModel) const {
147 /// \brief True if the subtarget should run MachineScheduler after aggressive
150 /// This currently replaces the SelectionDAG scheduler with the "source" order
151 /// scheduler (though see below for an option to turn this off and use the
152 /// TargetLowering preference). It does not yet disable the postRA scheduler.
153 virtual bool enableMachineScheduler() const;
155 /// \brief Support printing of [latency:throughput] comment in output .S file.
156 virtual bool supportPrintSchedInfo() const { return false; }
158 /// \brief True if the machine scheduler should disable the TLI preference
159 /// for preRA scheduling with the source level scheduler.
160 virtual bool enableMachineSchedDefaultSched() const { return true; }
162 /// \brief True if the subtarget should enable joining global copies.
164 /// By default this is enabled if the machine scheduler is enabled, but
165 /// can be overridden.
166 virtual bool enableJoinGlobalCopies() const;
168 /// True if the subtarget should run a scheduler after register allocation.
170 /// By default this queries the PostRAScheduling bit in the scheduling model
171 /// which is the preferred way to influence this.
172 virtual bool enablePostRAScheduler() const;
174 /// \brief True if the subtarget should run the atomic expansion pass.
175 virtual bool enableAtomicExpand() const;
177 /// \brief Override generic scheduling policy within a region.
179 /// This is a convenient way for targets that don't provide any custom
180 /// scheduling heuristics (no custom MachineSchedStrategy) to make
181 /// changes to the generic scheduling policy.
182 virtual void overrideSchedPolicy(MachineSchedPolicy &Policy,
183 unsigned NumRegionInstrs) const {}
185 // \brief Perform target specific adjustments to the latency of a schedule
187 virtual void adjustSchedDependency(SUnit *def, SUnit *use, SDep &dep) const {}
189 // For use with PostRAScheduling: get the anti-dependence breaking that should
190 // be performed before post-RA scheduling.
191 virtual AntiDepBreakMode getAntiDepBreakMode() const { return ANTIDEP_NONE; }
193 // For use with PostRAScheduling: in CriticalPathRCs, return any register
194 // classes that should only be considered for anti-dependence breaking if they
195 // are on the critical path.
196 virtual void getCriticalPathRCs(RegClassVector &CriticalPathRCs) const {
197 return CriticalPathRCs.clear();
200 // \brief Provide an ordered list of schedule DAG mutations for the post-RA
202 virtual void getPostRAMutations(
203 std::vector<std::unique_ptr<ScheduleDAGMutation>> &Mutations) const {
206 // \brief Provide an ordered list of schedule DAG mutations for the machine
208 virtual void getSMSMutations(
209 std::vector<std::unique_ptr<ScheduleDAGMutation>> &Mutations) const {
212 // For use with PostRAScheduling: get the minimum optimization level needed
213 // to enable post-RA scheduling.
214 virtual CodeGenOpt::Level getOptLevelToEnablePostRAScheduler() const {
215 return CodeGenOpt::Default;
218 /// \brief True if the subtarget should run the local reassignment
219 /// heuristic of the register allocator.
220 /// This heuristic may be compile time intensive, \p OptLevel provides
221 /// a finer grain to tune the register allocator.
222 virtual bool enableRALocalReassignment(CodeGenOpt::Level OptLevel) const;
224 /// \brief True if the subtarget should consider the cost of local intervals
225 /// created by a split candidate when choosing the best split candidate. This
226 /// heuristic may be compile time intensive.
227 virtual bool enableAdvancedRASplitCost() const;
229 /// \brief Enable use of alias analysis during code generation (during MI
230 /// scheduling, DAGCombine, etc.).
231 virtual bool useAA() const;
233 /// \brief Enable the use of the early if conversion pass.
234 virtual bool enableEarlyIfConversion() const { return false; }
236 /// \brief Return PBQPConstraint(s) for the target.
238 /// Override to provide custom PBQP constraints.
239 virtual std::unique_ptr<PBQPRAConstraint> getCustomPBQPConstraints() const {
243 /// Enable tracking of subregister liveness in register allocator.
244 /// Please use MachineRegisterInfo::subRegLivenessEnabled() instead where
246 virtual bool enableSubRegLiveness() const { return false; }
248 /// Returns string representation of scheduler comment
249 std::string getSchedInfoStr(const MachineInstr &MI) const override;
250 std::string getSchedInfoStr(MCInst const &MCI) const override;
253 } // end namespace llvm
255 #endif // LLVM_CODEGEN_TARGETSUBTARGETINFO_H