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TargetSubtargetInfo.h
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1 //===- llvm/CodeGen/TargetSubtargetInfo.h - Target Information --*- C++ -*-===//
2 //
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
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file describes the subtarget options of a Target machine.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_CODEGEN_TARGETSUBTARGETINFO_H
14 #define LLVM_CODEGEN_TARGETSUBTARGETINFO_H
15 
16 #include "llvm/ADT/APInt.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringRef.h"
24 #include "llvm/Support/CodeGen.h"
25 #include <memory>
26 #include <vector>
27 
28 
29 namespace llvm {
30 
31 class CallLowering;
32 class InstrItineraryData;
33 struct InstrStage;
34 class InstructionSelector;
35 class LegalizerInfo;
36 class MachineInstr;
37 struct MachineSchedPolicy;
38 struct MCReadAdvanceEntry;
39 struct MCWriteLatencyEntry;
40 struct MCWriteProcResEntry;
41 class RegisterBankInfo;
42 class SDep;
43 class SelectionDAGTargetInfo;
44 struct SubtargetFeatureKV;
45 struct SubtargetSubTypeKV;
46 struct SubtargetInfoKV;
47 class SUnit;
48 class TargetFrameLowering;
49 class TargetInstrInfo;
50 class TargetLowering;
51 class TargetRegisterClass;
52 class TargetRegisterInfo;
53 class TargetSchedModel;
54 class Triple;
55 
56 //===----------------------------------------------------------------------===//
57 ///
58 /// TargetSubtargetInfo - Generic base class for all target subtargets. All
59 /// Target-specific options that control code generation and printing should
60 /// be exposed through a TargetSubtargetInfo-derived class.
61 ///
63 protected: // Can only create subclasses...
67  const MCWriteProcResEntry *WPR,
68  const MCWriteLatencyEntry *WL,
69  const MCReadAdvanceEntry *RA, const InstrStage *IS,
70  const unsigned *OC, const unsigned *FP);
71 
72 public:
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 };
77 
78  TargetSubtargetInfo() = delete;
79  TargetSubtargetInfo(const TargetSubtargetInfo &) = delete;
81  ~TargetSubtargetInfo() override;
82 
83  virtual bool isXRaySupported() const { return false; }
84 
85  // Interfaces to the major aspects of target machine information:
86  //
87  // -- Instruction opcode and operand information
88  // -- Pipelines and scheduling information
89  // -- Stack frame information
90  // -- Selection DAG lowering information
91  // -- Call lowering information
92  //
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 {
97  return nullptr;
98  }
99  virtual const TargetLowering *getTargetLowering() const { return nullptr; }
101  return nullptr;
102  }
103  virtual const CallLowering *getCallLowering() const { return nullptr; }
104 
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.
110  return nullptr;
111  }
112 
113  virtual unsigned getHwMode() const { return 0; }
114 
115  /// Target can subclass this hook to select a different DAG scheduler.
118  return nullptr;
119  }
120 
121  virtual const LegalizerInfo *getLegalizerInfo() const { return nullptr; }
122 
123  /// getRegisterInfo - If register information is available, return it. If
124  /// not, return null.
125  virtual const TargetRegisterInfo *getRegisterInfo() const { return nullptr; }
126 
127  /// If the information for the register banks is available, return it.
128  /// Otherwise return nullptr.
129  virtual const RegisterBankInfo *getRegBankInfo() const { return nullptr; }
130 
131  /// getInstrItineraryData - Returns instruction itinerary data for the target
132  /// or specific subtarget.
133  virtual const InstrItineraryData *getInstrItineraryData() const {
134  return nullptr;
135  }
136 
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 {
144  return 0;
145  }
146 
147  /// Returns true if MI is a dependency breaking zero-idiom instruction for the
148  /// subtarget.
149  ///
150  /// This function also sets bits in Mask related to input operands that
151  /// are not in a data dependency relationship. There is one bit for each
152  /// machine operand; implicit operands follow explicit operands in the bit
153  /// representation used for Mask. An empty (i.e. a mask with all bits
154  /// cleared) means: data dependencies are "broken" for all the explicit input
155  /// machine operands of MI.
156  virtual bool isZeroIdiom(const MachineInstr *MI, APInt &Mask) const {
157  return false;
158  }
159 
160  /// Returns true if MI is a dependency breaking instruction for the subtarget.
161  ///
162  /// Similar in behavior to `isZeroIdiom`. However, it knows how to identify
163  /// all dependency breaking instructions (i.e. not just zero-idioms).
164  ///
165  /// As for `isZeroIdiom`, this method returns a mask of "broken" dependencies.
166  /// (See method `isZeroIdiom` for a detailed description of Mask).
167  virtual bool isDependencyBreaking(const MachineInstr *MI, APInt &Mask) const {
168  return isZeroIdiom(MI, Mask);
169  }
170 
171  /// Returns true if MI is a candidate for move elimination.
172  ///
173  /// A candidate for move elimination may be optimized out at register renaming
174  /// stage. Subtargets can specify the set of optimizable moves by
175  /// instantiating tablegen class `IsOptimizableRegisterMove` (see
176  /// llvm/Target/TargetInstrPredicate.td).
177  ///
178  /// SubtargetEmitter is responsible for processing all the definitions of class
179  /// IsOptimizableRegisterMove, and auto-generate an override for this method.
180  virtual bool isOptimizableRegisterMove(const MachineInstr *MI) const {
181  return false;
182  }
183 
184  /// True if the subtarget should run MachineScheduler after aggressive
185  /// coalescing.
186  ///
187  /// This currently replaces the SelectionDAG scheduler with the "source" order
188  /// scheduler (though see below for an option to turn this off and use the
189  /// TargetLowering preference). It does not yet disable the postRA scheduler.
190  virtual bool enableMachineScheduler() const;
191 
192  /// True if the machine scheduler should disable the TLI preference
193  /// for preRA scheduling with the source level scheduler.
194  virtual bool enableMachineSchedDefaultSched() const { return true; }
195 
196  /// True if the subtarget should run MachinePipeliner
197  virtual bool enableMachinePipeliner() const { return true; };
198 
199  /// True if the subtarget should enable joining global copies.
200  ///
201  /// By default this is enabled if the machine scheduler is enabled, but
202  /// can be overridden.
203  virtual bool enableJoinGlobalCopies() const;
204 
205  /// True if the subtarget should run a scheduler after register allocation.
206  ///
207  /// By default this queries the PostRAScheduling bit in the scheduling model
208  /// which is the preferred way to influence this.
209  virtual bool enablePostRAScheduler() const;
210 
211  /// True if the subtarget should run the atomic expansion pass.
212  virtual bool enableAtomicExpand() const;
213 
214  /// True if the subtarget should run the indirectbr expansion pass.
215  virtual bool enableIndirectBrExpand() const;
216 
217  /// Override generic scheduling policy within a region.
218  ///
219  /// This is a convenient way for targets that don't provide any custom
220  /// scheduling heuristics (no custom MachineSchedStrategy) to make
221  /// changes to the generic scheduling policy.
223  unsigned NumRegionInstrs) const {}
224 
225  // Perform target specific adjustments to the latency of a schedule
226  // dependency.
227  virtual void adjustSchedDependency(SUnit *def, SUnit *use, SDep &dep) const {}
228 
229  // For use with PostRAScheduling: get the anti-dependence breaking that should
230  // be performed before post-RA scheduling.
231  virtual AntiDepBreakMode getAntiDepBreakMode() const { return ANTIDEP_NONE; }
232 
233  // For use with PostRAScheduling: in CriticalPathRCs, return any register
234  // classes that should only be considered for anti-dependence breaking if they
235  // are on the critical path.
236  virtual void getCriticalPathRCs(RegClassVector &CriticalPathRCs) const {
237  return CriticalPathRCs.clear();
238  }
239 
240  // Provide an ordered list of schedule DAG mutations for the post-RA
241  // scheduler.
242  virtual void getPostRAMutations(
243  std::vector<std::unique_ptr<ScheduleDAGMutation>> &Mutations) const {
244  }
245 
246  // Provide an ordered list of schedule DAG mutations for the machine
247  // pipeliner.
248  virtual void getSMSMutations(
249  std::vector<std::unique_ptr<ScheduleDAGMutation>> &Mutations) const {
250  }
251 
252  /// Default to DFA for resource management, return false when target will use
253  /// ProcResource in InstrSchedModel instead.
254  virtual bool useDFAforSMS() const { return true; }
255 
256  // For use with PostRAScheduling: get the minimum optimization level needed
257  // to enable post-RA scheduling.
259  return CodeGenOpt::Default;
260  }
261 
262  /// True if the subtarget should run the local reassignment
263  /// heuristic of the register allocator.
264  /// This heuristic may be compile time intensive, \p OptLevel provides
265  /// a finer grain to tune the register allocator.
266  virtual bool enableRALocalReassignment(CodeGenOpt::Level OptLevel) const;
267 
268  /// True if the subtarget should consider the cost of local intervals
269  /// created by a split candidate when choosing the best split candidate. This
270  /// heuristic may be compile time intensive.
271  virtual bool enableAdvancedRASplitCost() const;
272 
273  /// Enable use of alias analysis during code generation (during MI
274  /// scheduling, DAGCombine, etc.).
275  virtual bool useAA() const;
276 
277  /// Enable the use of the early if conversion pass.
278  virtual bool enableEarlyIfConversion() const { return false; }
279 
280  /// Return PBQPConstraint(s) for the target.
281  ///
282  /// Override to provide custom PBQP constraints.
283  virtual std::unique_ptr<PBQPRAConstraint> getCustomPBQPConstraints() const {
284  return nullptr;
285  }
286 
287  /// Enable tracking of subregister liveness in register allocator.
288  /// Please use MachineRegisterInfo::subRegLivenessEnabled() instead where
289  /// possible.
290  virtual bool enableSubRegLiveness() const { return false; }
291 
292  /// This is called after a .mir file was loaded.
293  virtual void mirFileLoaded(MachineFunction &MF) const;
294 
295  /// True if the register allocator should use the allocation orders exactly as
296  /// written in the tablegen descriptions, false if it should allocate
297  /// the specified physical register later if is it callee-saved.
299  unsigned PhysReg) const {
300  return false;
301  }
302 };
303 
304 } // end namespace llvm
305 
306 #endif // LLVM_CODEGEN_TARGETSUBTARGETINFO_H
virtual void getCriticalPathRCs(RegClassVector &CriticalPathRCs) const
virtual bool enableMachinePipeliner() const
True if the subtarget should run MachinePipeliner.
virtual bool isOptimizableRegisterMove(const MachineInstr *MI) const
Returns true if MI is a candidate for move elimination.
virtual bool enableJoinGlobalCopies() const
True if the subtarget should enable joining global copies.
This class represents lattice values for constants.
Definition: AllocatorList.h:23
virtual const TargetRegisterInfo * getRegisterInfo() const
getRegisterInfo - If register information is available, return it.
virtual const TargetLowering * getTargetLowering() const
virtual bool ignoreCSRForAllocationOrder(const MachineFunction &MF, unsigned PhysReg) const
True if the register allocator should use the allocation orders exactly as written in the tablegen de...
virtual const RegisterBankInfo * getRegBankInfo() const
If the information for the register banks is available, return it.
virtual unsigned resolveSchedClass(unsigned SchedClass, const MachineInstr *MI, const TargetSchedModel *SchedModel) const
Resolve a SchedClass at runtime, where SchedClass identifies an MCSchedClassDesc with the isVariant p...
virtual unsigned getHwMode() const
virtual void adjustSchedDependency(SUnit *def, SUnit *use, SDep &dep) const
virtual bool isXRaySupported() const
virtual bool enableEarlyIfConversion() const
Enable the use of the early if conversion pass.
SI optimize exec mask operations pre RA
virtual std::unique_ptr< PBQPRAConstraint > getCustomPBQPConstraints() const
Return PBQPConstraint(s) for the target.
virtual bool useDFAforSMS() const
Default to DFA for resource management, return false when target will use ProcResource in InstrSchedM...
Holds all the information related to register banks.
Provide an instruction scheduling machine model to CodeGen passes.
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:41
virtual bool enableMachineSchedDefaultSched() const
True if the machine scheduler should disable the TLI preference for preRA scheduling with the source ...
ScheduleDAGSDNodes *(*)(SelectionDAGISel *, CodeGenOpt::Level) FunctionPassCtor
This class defines information used to lower LLVM code to legal SelectionDAG operators that the targe...
virtual AntiDepBreakMode getAntiDepBreakMode() const
This file implements a class to represent arbitrary precision integral constant values and operations...
virtual void overrideSchedPolicy(MachineSchedPolicy &Policy, unsigned NumRegionInstrs) const
Override generic scheduling policy within a region.
virtual bool isZeroIdiom(const MachineInstr *MI, APInt &Mask) const
Returns true if MI is a dependency breaking zero-idiom instruction for the subtarget.
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:32
Itinerary data supplied by a subtarget to be used by a target.
virtual const TargetInstrInfo * getInstrInfo() const
virtual void mirFileLoaded(MachineFunction &MF) const
This is called after a .mir file was loaded.
virtual const InstrItineraryData * getInstrItineraryData() const
getInstrItineraryData - Returns instruction itinerary data for the target or specific subtarget...
TargetInstrInfo - Interface to description of machine instruction set.
Scheduling dependency.
Definition: ScheduleDAG.h:49
virtual bool enableSubRegLiveness() const
Enable tracking of subregister liveness in register allocator.
virtual const LegalizerInfo * getLegalizerInfo() const
Move duplicate certain instructions close to their use
Definition: Localizer.cpp:27
Identify one of the processor resource kinds consumed by a particular scheduling class for the specif...
Definition: MCSchedule.h:64
virtual void getSMSMutations(std::vector< std::unique_ptr< ScheduleDAGMutation >> &Mutations) const
virtual bool enableIndirectBrExpand() const
True if the subtarget should run the indirectbr expansion pass.
virtual bool isDependencyBreaking(const MachineInstr *MI, APInt &Mask) const
Returns true if MI is a dependency breaking instruction for the subtarget.
enum { ANTIDEP_NONE, ANTIDEP_CRITICAL, ANTIDEP_ALL } AntiDepBreakMode
virtual InstructionSelector * getInstructionSelector() const
virtual const CallLowering * getCallLowering() const
Targets can subclass this to parameterize the SelectionDAG lowering and instruction selection process...
TargetRegisterInfo base class - We assume that the target defines a static array of TargetRegisterDes...
virtual bool enableMachineScheduler() const
True if the subtarget should run MachineScheduler after aggressive coalescing.
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:43
Specify the latency in cpu cycles for a particular scheduling class and def index.
Definition: MCSchedule.h:78
Information about stack frame layout on the target.
Class for arbitrary precision integers.
Definition: APInt.h:69
RegisterBankInfo(RegisterBank **RegBanks, unsigned NumRegBanks)
Create a RegisterBankInfo that can accommodate up to NumRegBanks RegisterBank instances.
virtual bool enableAtomicExpand() const
True if the subtarget should run the atomic expansion pass.
Specify the number of cycles allowed after instruction issue before a particular use operand reads it...
Definition: MCSchedule.h:95
TargetSubtargetInfo - Generic base class for all target subtargets.
Provides the logic to select generic machine instructions.
Define a generic scheduling policy for targets that don&#39;t provide their own MachineSchedStrategy.
Representation of each machine instruction.
Definition: MachineInstr.h:64
virtual bool enableRALocalReassignment(CodeGenOpt::Level OptLevel) const
True if the subtarget should run the local reassignment heuristic of the register allocator...
These values represent a non-pipelined step in the execution of an instruction.
TargetSubtargetInfo & operator=(const TargetSubtargetInfo &)=delete
virtual void getPostRAMutations(std::vector< std::unique_ptr< ScheduleDAGMutation >> &Mutations) const
virtual const TargetFrameLowering * getFrameLowering() const
Generic base class for all target subtargets.
virtual bool enablePostRAScheduler() const
True if the subtarget should run a scheduler after register allocation.
virtual bool enableAdvancedRASplitCost() const
True if the subtarget should consider the cost of local intervals created by a split candidate when c...
std::underlying_type< E >::type Mask()
Get a bitmask with 1s in all places up to the high-order bit of E&#39;s largest value.
Definition: BitmaskEnum.h:80
IRTranslator LLVM IR MI
virtual bool useAA() const
Enable use of alias analysis during code generation (during MI scheduling, DAGCombine, etc.).
virtual const SelectionDAGTargetInfo * getSelectionDAGInfo() const
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
virtual CodeGenOpt::Level getOptLevelToEnablePostRAScheduler() const
virtual RegisterScheduler::FunctionPassCtor getDAGScheduler(CodeGenOpt::Level) const
Target can subclass this hook to select a different DAG scheduler.
Scheduling unit. This is a node in the scheduling DAG.
Definition: ScheduleDAG.h:242