1 //===-- llvm/Target/TargetInstrInfo.h - Instruction Info --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file describes the target machine instructions to the code generator.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_TARGET_TARGETINSTRINFO_H
15 #define LLVM_TARGET_TARGETINSTRINFO_H
17 #include "llvm/CodeGen/MachineBasicBlock.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/Support/DataTypes.h"
27 class MachineCodeForInstruction;
28 class TargetRegisterClass;
31 //---------------------------------------------------------------------------
32 // Data types used to define information about a single machine instruction
33 //---------------------------------------------------------------------------
35 typedef short MachineOpCode;
36 typedef unsigned InstrSchedClass;
38 //---------------------------------------------------------------------------
39 // struct TargetInstrDescriptor:
40 // Predefined information about each machine instruction.
41 // Designed to initialized statically.
44 const unsigned M_BRANCH_FLAG = 1 << 0;
45 const unsigned M_CALL_FLAG = 1 << 1;
46 const unsigned M_RET_FLAG = 1 << 2;
47 const unsigned M_BARRIER_FLAG = 1 << 3;
48 const unsigned M_DELAY_SLOT_FLAG = 1 << 4;
49 const unsigned M_LOAD_FLAG = 1 << 5;
50 const unsigned M_STORE_FLAG = 1 << 6;
52 // M_CONVERTIBLE_TO_3_ADDR - This is a 2-address instruction which can be
53 // changed into a 3-address instruction if the first two operands cannot be
54 // assigned to the same register. The target must implement the
55 // TargetInstrInfo::convertToThreeAddress method for this instruction.
56 const unsigned M_CONVERTIBLE_TO_3_ADDR = 1 << 7;
58 // This M_COMMUTABLE - is a 2- or 3-address instruction (of the form X = op Y,
59 // Z), which produces the same result if Y and Z are exchanged.
60 const unsigned M_COMMUTABLE = 1 << 8;
62 // M_TERMINATOR_FLAG - Is this instruction part of the terminator for a basic
63 // block? Typically this is things like return and branch instructions.
64 // Various passes use this to insert code into the bottom of a basic block, but
65 // before control flow occurs.
66 const unsigned M_TERMINATOR_FLAG = 1 << 9;
68 // M_USES_CUSTOM_DAG_SCHED_INSERTION - Set if this instruction requires custom
69 // insertion support when the DAG scheduler is inserting it into a machine basic
71 const unsigned M_USES_CUSTOM_DAG_SCHED_INSERTION = 1 << 10;
73 // M_VARIABLE_OPS - Set if this instruction can have a variable number of extra
74 // operands in addition to the minimum number operands specified.
75 const unsigned M_VARIABLE_OPS = 1 << 11;
77 // M_PREDICABLE - Set if this instruction has a predicate operand that
78 // controls execution. It may be set to 'always'.
79 const unsigned M_PREDICABLE = 1 << 12;
81 // M_REMATERIALIZIBLE - Set if this instruction can be trivally re-materialized
82 // at any time, e.g. constant generation, load from constant pool.
83 const unsigned M_REMATERIALIZIBLE = 1 << 13;
85 // M_CLOBBERS_PRED - Set if this instruction may clobbers the condition code
86 // register and / or registers that are used to predicate instructions.
87 const unsigned M_CLOBBERS_PRED = 1 << 14;
89 // M_NOT_DUPLICABLE - Set if this instruction cannot be safely duplicated.
90 // (e.g. instructions with unique labels attached).
91 const unsigned M_NOT_DUPLICABLE = 1 << 15;
93 // Machine operand flags
94 // M_LOOK_UP_PTR_REG_CLASS - Set if this operand is a pointer value and it
95 // requires a callback to look up its register class.
96 const unsigned M_LOOK_UP_PTR_REG_CLASS = 1 << 0;
98 /// M_PREDICATE_OPERAND - Set if this is one of the operands that made up of the
99 /// predicate operand that controls an M_PREDICATED instruction.
100 const unsigned M_PREDICATE_OPERAND = 1 << 1;
103 // Operand constraints: only "tied_to" for now.
104 enum OperandConstraint {
105 TIED_TO = 0 // Must be allocated the same register as.
109 /// TargetOperandInfo - This holds information about one operand of a machine
110 /// instruction, indicating the register class for register operands, etc.
112 class TargetOperandInfo {
114 /// RegClass - This specifies the register class enumeration of the operand
115 /// if the operand is a register. If not, this contains 0.
116 unsigned short RegClass;
117 unsigned short Flags;
118 /// Lower 16 bits are used to specify which constraints are set. The higher 16
119 /// bits are used to specify the value of constraints (4 bits each).
120 unsigned int Constraints;
121 /// Currently no other information.
125 class TargetInstrDescriptor {
127 MachineOpCode Opcode; // The opcode.
128 unsigned short numOperands; // Num of args (may be more if variable_ops).
129 const char * Name; // Assembly language mnemonic for the opcode.
130 InstrSchedClass schedClass; // enum identifying instr sched class
131 unsigned Flags; // flags identifying machine instr class
132 unsigned TSFlags; // Target Specific Flag values
133 const unsigned *ImplicitUses; // Registers implicitly read by this instr
134 const unsigned *ImplicitDefs; // Registers implicitly defined by this instr
135 const TargetOperandInfo *OpInfo; // 'numOperands' entries about operands.
137 /// getOperandConstraint - Returns the value of the specific constraint if
138 /// it is set. Returns -1 if it is not set.
139 int getOperandConstraint(unsigned OpNum,
140 TOI::OperandConstraint Constraint) const {
141 assert((OpNum < numOperands || (Flags & M_VARIABLE_OPS)) &&
142 "Invalid operand # of TargetInstrInfo");
143 if (OpNum < numOperands &&
144 (OpInfo[OpNum].Constraints & (1 << Constraint))) {
145 unsigned Pos = 16 + Constraint * 4;
146 return (int)(OpInfo[OpNum].Constraints >> Pos) & 0xf;
151 /// findTiedToSrcOperand - Returns the operand that is tied to the specified
152 /// dest operand. Returns -1 if there isn't one.
153 int findTiedToSrcOperand(unsigned OpNum) const;
157 //---------------------------------------------------------------------------
159 /// TargetInstrInfo - Interface to description of machine instructions
161 class TargetInstrInfo {
162 const TargetInstrDescriptor* desc; // raw array to allow static init'n
163 unsigned NumOpcodes; // number of entries in the desc array
164 unsigned numRealOpCodes; // number of non-dummy op codes
166 TargetInstrInfo(const TargetInstrInfo &); // DO NOT IMPLEMENT
167 void operator=(const TargetInstrInfo &); // DO NOT IMPLEMENT
169 TargetInstrInfo(const TargetInstrDescriptor *desc, unsigned NumOpcodes);
170 virtual ~TargetInstrInfo();
172 // Invariant opcodes: All instruction sets have these as their low opcodes.
179 unsigned getNumOpcodes() const { return NumOpcodes; }
181 /// get - Return the machine instruction descriptor that corresponds to the
182 /// specified instruction opcode.
184 const TargetInstrDescriptor& get(MachineOpCode Opcode) const {
185 assert((unsigned)Opcode < NumOpcodes);
189 const char *getName(MachineOpCode Opcode) const {
190 return get(Opcode).Name;
193 int getNumOperands(MachineOpCode Opcode) const {
194 return get(Opcode).numOperands;
197 InstrSchedClass getSchedClass(MachineOpCode Opcode) const {
198 return get(Opcode).schedClass;
201 const unsigned *getImplicitUses(MachineOpCode Opcode) const {
202 return get(Opcode).ImplicitUses;
205 const unsigned *getImplicitDefs(MachineOpCode Opcode) const {
206 return get(Opcode).ImplicitDefs;
211 // Query instruction class flags according to the machine-independent
212 // flags listed above.
214 bool isReturn(MachineOpCode Opcode) const {
215 return get(Opcode).Flags & M_RET_FLAG;
218 bool isCommutableInstr(MachineOpCode Opcode) const {
219 return get(Opcode).Flags & M_COMMUTABLE;
221 bool isTerminatorInstr(MachineOpCode Opcode) const {
222 return get(Opcode).Flags & M_TERMINATOR_FLAG;
225 bool isBranch(MachineOpCode Opcode) const {
226 return get(Opcode).Flags & M_BRANCH_FLAG;
229 /// isBarrier - Returns true if the specified instruction stops control flow
230 /// from executing the instruction immediately following it. Examples include
231 /// unconditional branches and return instructions.
232 bool isBarrier(MachineOpCode Opcode) const {
233 return get(Opcode).Flags & M_BARRIER_FLAG;
236 bool isCall(MachineOpCode Opcode) const {
237 return get(Opcode).Flags & M_CALL_FLAG;
239 bool isLoad(MachineOpCode Opcode) const {
240 return get(Opcode).Flags & M_LOAD_FLAG;
242 bool isStore(MachineOpCode Opcode) const {
243 return get(Opcode).Flags & M_STORE_FLAG;
246 /// hasDelaySlot - Returns true if the specified instruction has a delay slot
247 /// which must be filled by the code generator.
248 bool hasDelaySlot(MachineOpCode Opcode) const {
249 return get(Opcode).Flags & M_DELAY_SLOT_FLAG;
252 /// usesCustomDAGSchedInsertionHook - Return true if this instruction requires
253 /// custom insertion support when the DAG scheduler is inserting it into a
254 /// machine basic block.
255 bool usesCustomDAGSchedInsertionHook(MachineOpCode Opcode) const {
256 return get(Opcode).Flags & M_USES_CUSTOM_DAG_SCHED_INSERTION;
259 bool hasVariableOperands(MachineOpCode Opcode) const {
260 return get(Opcode).Flags & M_VARIABLE_OPS;
263 bool isPredicable(MachineOpCode Opcode) const {
264 return get(Opcode).Flags & M_PREDICABLE;
267 bool isReMaterializable(MachineOpCode Opcode) const {
268 return get(Opcode).Flags & M_REMATERIALIZIBLE;
271 bool clobbersPredicate(MachineOpCode Opcode) const {
272 return get(Opcode).Flags & M_CLOBBERS_PRED;
275 bool isNotDuplicable(MachineOpCode Opcode) const {
276 return get(Opcode).Flags & M_NOT_DUPLICABLE;
279 /// getOperandConstraint - Returns the value of the specific constraint if
280 /// it is set. Returns -1 if it is not set.
281 int getOperandConstraint(MachineOpCode Opcode, unsigned OpNum,
282 TOI::OperandConstraint Constraint) const {
283 return get(Opcode).getOperandConstraint(OpNum, Constraint);
286 /// Return true if the instruction is a register to register move
287 /// and leave the source and dest operands in the passed parameters.
288 virtual bool isMoveInstr(const MachineInstr& MI,
290 unsigned& destReg) const {
294 /// isLoadFromStackSlot - If the specified machine instruction is a direct
295 /// load from a stack slot, return the virtual or physical register number of
296 /// the destination along with the FrameIndex of the loaded stack slot. If
297 /// not, return 0. This predicate must return 0 if the instruction has
298 /// any side effects other than loading from the stack slot.
299 virtual unsigned isLoadFromStackSlot(MachineInstr *MI, int &FrameIndex) const{
303 /// isStoreToStackSlot - If the specified machine instruction is a direct
304 /// store to a stack slot, return the virtual or physical register number of
305 /// the source reg along with the FrameIndex of the loaded stack slot. If
306 /// not, return 0. This predicate must return 0 if the instruction has
307 /// any side effects other than storing to the stack slot.
308 virtual unsigned isStoreToStackSlot(MachineInstr *MI, int &FrameIndex) const {
312 /// isOtherReMaterializableLoad - If the specified machine instruction is a
313 /// direct load that is trivially rematerializable, not counting loads from
314 /// stack slots, return true. If not, return false. This predicate must
315 /// return false if the instruction has any side effects other than
316 /// producing the value from the load, or if it requres any address
317 /// registers that are not always available.
318 virtual bool isOtherReMaterializableLoad(MachineInstr *MI) const {
322 /// convertToThreeAddress - This method must be implemented by targets that
323 /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
324 /// may be able to convert a two-address instruction into one or moretrue
325 /// three-address instructions on demand. This allows the X86 target (for
326 /// example) to convert ADD and SHL instructions into LEA instructions if they
327 /// would require register copies due to two-addressness.
329 /// This method returns a null pointer if the transformation cannot be
330 /// performed, otherwise it returns the last new instruction.
332 virtual MachineInstr *
333 convertToThreeAddress(MachineFunction::iterator &MFI,
334 MachineBasicBlock::iterator &MBBI, LiveVariables &LV) const {
338 /// commuteInstruction - If a target has any instructions that are commutable,
339 /// but require converting to a different instruction or making non-trivial
340 /// changes to commute them, this method can overloaded to do this. The
341 /// default implementation of this method simply swaps the first two operands
342 /// of MI and returns it.
344 /// If a target wants to make more aggressive changes, they can construct and
345 /// return a new machine instruction. If an instruction cannot commute, it
346 /// can also return null.
348 virtual MachineInstr *commuteInstruction(MachineInstr *MI) const;
350 /// AnalyzeBranch - Analyze the branching code at the end of MBB, returning
351 /// true if it cannot be understood (e.g. it's a switch dispatch or isn't
352 /// implemented for a target). Upon success, this returns false and returns
353 /// with the following information in various cases:
355 /// 1. If this block ends with no branches (it just falls through to its succ)
356 /// just return false, leaving TBB/FBB null.
357 /// 2. If this block ends with only an unconditional branch, it sets TBB to be
358 /// the destination block.
359 /// 3. If this block ends with an conditional branch and it falls through to
360 /// an successor block, it sets TBB to be the branch destination block and a
361 /// list of operands that evaluate the condition. These
362 /// operands can be passed to other TargetInstrInfo methods to create new
364 /// 4. If this block ends with an conditional branch and an unconditional
365 /// block, it returns the 'true' destination in TBB, the 'false' destination
366 /// in FBB, and a list of operands that evaluate the condition. These
367 /// operands can be passed to other TargetInstrInfo methods to create new
370 /// Note that RemoveBranch and InsertBranch must be implemented to support
371 /// cases where this method returns success.
373 virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
374 MachineBasicBlock *&FBB,
375 std::vector<MachineOperand> &Cond) const {
379 /// RemoveBranch - Remove the branching code at the end of the specific MBB.
380 /// this is only invoked in cases where AnalyzeBranch returns success. It
381 /// returns the number of instructions that were removed.
382 virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const {
383 assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!");
387 /// InsertBranch - Insert a branch into the end of the specified
388 /// MachineBasicBlock. This operands to this method are the same as those
389 /// returned by AnalyzeBranch. This is invoked in cases where AnalyzeBranch
390 /// returns success and when an unconditional branch (TBB is non-null, FBB is
391 /// null, Cond is empty) needs to be inserted. It returns the number of
392 /// instructions inserted.
393 virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
394 MachineBasicBlock *FBB,
395 const std::vector<MachineOperand> &Cond) const {
396 assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!");
400 /// BlockHasNoFallThrough - Return true if the specified block does not
401 /// fall-through into its successor block. This is primarily used when a
402 /// branch is unanalyzable. It is useful for things like unconditional
403 /// indirect branches (jump tables).
404 virtual bool BlockHasNoFallThrough(MachineBasicBlock &MBB) const {
408 /// ReverseBranchCondition - Reverses the branch condition of the specified
409 /// condition list, returning false on success and true if it cannot be
411 virtual bool ReverseBranchCondition(std::vector<MachineOperand> &Cond) const {
415 /// insertNoop - Insert a noop into the instruction stream at the specified
417 virtual void insertNoop(MachineBasicBlock &MBB,
418 MachineBasicBlock::iterator MI) const {
419 assert(0 && "Target didn't implement insertNoop!");
423 /// isPredicated - Returns true if the instruction is already predicated.
425 virtual bool isPredicated(const MachineInstr *MI) const {
429 /// isUnpredicatedTerminator - Returns true if the instruction is a
430 /// terminator instruction that has not been predicated.
431 virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const;
433 /// PredicateInstruction - Convert the instruction into a predicated
434 /// instruction. It returns true if the operation was successful.
436 bool PredicateInstruction(MachineInstr *MI,
437 const std::vector<MachineOperand> &Pred) const;
439 /// SubsumesPredicate - Returns true if the first specified predicate
440 /// subsumes the second, e.g. GE subsumes GT.
442 bool SubsumesPredicate(const std::vector<MachineOperand> &Pred1,
443 const std::vector<MachineOperand> &Pred2) const {
447 /// getPointerRegClass - Returns a TargetRegisterClass used for pointer
449 virtual const TargetRegisterClass *getPointerRegClass() const {
450 assert(0 && "Target didn't implement getPointerRegClass!");
452 return 0; // Must return a value in order to compile with VS 2005
456 } // End llvm namespace