1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
|
#pragma once
#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
#endif
//===-- llvm/MC/MCInstrDesc.h - Instruction Descriptors -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the MCOperandInfo and MCInstrDesc classes, which
// are used to describe target instructions and their operands.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCINSTRDESC_H
#define LLVM_MC_MCINSTRDESC_H
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Support/DataTypes.h"
namespace llvm {
class MCInst;
//===----------------------------------------------------------------------===//
// Machine Operand Flags and Description
//===----------------------------------------------------------------------===//
namespace MCOI {
/// Operand constraints. These are encoded in 16 bits with one of the
/// low-order 3 bits specifying that a constraint is present and the
/// corresponding high-order hex digit specifying the constraint value.
/// This allows for a maximum of 3 constraints.
enum OperandConstraint {
TIED_TO = 0, // Must be allocated the same register as specified value.
EARLY_CLOBBER // If present, operand is an early clobber register.
};
// Define a macro to produce each constraint value.
#define MCOI_TIED_TO(op) \
((1 << MCOI::TIED_TO) | ((op) << (4 + MCOI::TIED_TO * 4)))
#define MCOI_EARLY_CLOBBER \
(1 << MCOI::EARLY_CLOBBER)
/// These are flags set on operands, but should be considered
/// private, all access should go through the MCOperandInfo accessors.
/// See the accessors for a description of what these are.
enum OperandFlags {
LookupPtrRegClass = 0,
Predicate,
OptionalDef,
BranchTarget
};
/// Operands are tagged with one of the values of this enum.
enum OperandType {
OPERAND_UNKNOWN = 0,
OPERAND_IMMEDIATE = 1,
OPERAND_REGISTER = 2,
OPERAND_MEMORY = 3,
OPERAND_PCREL = 4,
OPERAND_FIRST_GENERIC = 6,
OPERAND_GENERIC_0 = 6,
OPERAND_GENERIC_1 = 7,
OPERAND_GENERIC_2 = 8,
OPERAND_GENERIC_3 = 9,
OPERAND_GENERIC_4 = 10,
OPERAND_GENERIC_5 = 11,
OPERAND_LAST_GENERIC = 11,
OPERAND_FIRST_GENERIC_IMM = 12,
OPERAND_GENERIC_IMM_0 = 12,
OPERAND_LAST_GENERIC_IMM = 12,
OPERAND_FIRST_TARGET = 13,
};
} // namespace MCOI
/// This holds information about one operand of a machine instruction,
/// indicating the register class for register operands, etc.
class MCOperandInfo {
public:
/// This specifies the register class enumeration of the operand
/// if the operand is a register. If isLookupPtrRegClass is set, then this is
/// an index that is passed to TargetRegisterInfo::getPointerRegClass(x) to
/// get a dynamic register class.
int16_t RegClass;
/// These are flags from the MCOI::OperandFlags enum.
uint8_t Flags;
/// Information about the type of the operand.
uint8_t OperandType;
/// Operand constraints (see OperandConstraint enum).
uint16_t Constraints;
/// Set if this operand is a pointer value and it requires a callback
/// to look up its register class.
bool isLookupPtrRegClass() const {
return Flags & (1 << MCOI::LookupPtrRegClass);
}
/// Set if this is one of the operands that made up of the predicate
/// operand that controls an isPredicable() instruction.
bool isPredicate() const { return Flags & (1 << MCOI::Predicate); }
/// Set if this operand is a optional def.
bool isOptionalDef() const { return Flags & (1 << MCOI::OptionalDef); }
/// Set if this operand is a branch target.
bool isBranchTarget() const { return Flags & (1 << MCOI::BranchTarget); }
bool isGenericType() const {
return OperandType >= MCOI::OPERAND_FIRST_GENERIC &&
OperandType <= MCOI::OPERAND_LAST_GENERIC;
}
unsigned getGenericTypeIndex() const {
assert(isGenericType() && "non-generic types don't have an index");
return OperandType - MCOI::OPERAND_FIRST_GENERIC;
}
bool isGenericImm() const {
return OperandType >= MCOI::OPERAND_FIRST_GENERIC_IMM &&
OperandType <= MCOI::OPERAND_LAST_GENERIC_IMM;
}
unsigned getGenericImmIndex() const {
assert(isGenericImm() && "non-generic immediates don't have an index");
return OperandType - MCOI::OPERAND_FIRST_GENERIC_IMM;
}
};
//===----------------------------------------------------------------------===//
// Machine Instruction Flags and Description
//===----------------------------------------------------------------------===//
namespace MCID {
/// These should be considered private to the implementation of the
/// MCInstrDesc class. Clients should use the predicate methods on MCInstrDesc,
/// not use these directly. These all correspond to bitfields in the
/// MCInstrDesc::Flags field.
enum Flag {
PreISelOpcode = 0,
Variadic,
HasOptionalDef,
Pseudo,
Return,
EHScopeReturn,
Call,
Barrier,
Terminator,
Branch,
IndirectBranch,
Compare,
MoveImm,
MoveReg,
Bitcast,
Select,
DelaySlot,
FoldableAsLoad,
MayLoad,
MayStore,
MayRaiseFPException,
Predicable,
NotDuplicable,
UnmodeledSideEffects,
Commutable,
ConvertibleTo3Addr,
UsesCustomInserter,
HasPostISelHook,
Rematerializable,
CheapAsAMove,
ExtraSrcRegAllocReq,
ExtraDefRegAllocReq,
RegSequence,
ExtractSubreg,
InsertSubreg,
Convergent,
Add,
Trap,
VariadicOpsAreDefs,
Authenticated,
};
} // namespace MCID
/// Describe properties that are true of each instruction in the target
/// description file. This captures information about side effects, register
/// use and many other things. There is one instance of this struct for each
/// target instruction class, and the MachineInstr class points to this struct
/// directly to describe itself.
class MCInstrDesc {
public:
unsigned short Opcode; // The opcode number
unsigned short NumOperands; // Num of args (may be more if variable_ops)
unsigned char NumDefs; // Num of args that are definitions
unsigned char Size; // Number of bytes in encoding.
unsigned short SchedClass; // enum identifying instr sched class
uint64_t Flags; // Flags identifying machine instr class
uint64_t TSFlags; // Target Specific Flag values
const MCPhysReg *ImplicitUses; // Registers implicitly read by this instr
const MCPhysReg *ImplicitDefs; // Registers implicitly defined by this instr
const MCOperandInfo *OpInfo; // 'NumOperands' entries about operands
/// Returns the value of the specified operand constraint if
/// it is present. Returns -1 if it is not present.
int getOperandConstraint(unsigned OpNum,
MCOI::OperandConstraint Constraint) const {
if (OpNum < NumOperands &&
(OpInfo[OpNum].Constraints & (1 << Constraint))) {
unsigned ValuePos = 4 + Constraint * 4;
return (int)(OpInfo[OpNum].Constraints >> ValuePos) & 0x0f;
}
return -1;
}
/// Return the opcode number for this descriptor.
unsigned getOpcode() const { return Opcode; }
/// Return the number of declared MachineOperands for this
/// MachineInstruction. Note that variadic (isVariadic() returns true)
/// instructions may have additional operands at the end of the list, and note
/// that the machine instruction may include implicit register def/uses as
/// well.
unsigned getNumOperands() const { return NumOperands; }
using const_opInfo_iterator = const MCOperandInfo *;
const_opInfo_iterator opInfo_begin() const { return OpInfo; }
const_opInfo_iterator opInfo_end() const { return OpInfo + NumOperands; }
iterator_range<const_opInfo_iterator> operands() const {
return make_range(opInfo_begin(), opInfo_end());
}
/// Return the number of MachineOperands that are register
/// definitions. Register definitions always occur at the start of the
/// machine operand list. This is the number of "outs" in the .td file,
/// and does not include implicit defs.
unsigned getNumDefs() const { return NumDefs; }
/// Return flags of this instruction.
uint64_t getFlags() const { return Flags; }
/// \returns true if this instruction is emitted before instruction selection
/// and should be legalized/regbankselected/selected.
bool isPreISelOpcode() const { return Flags & (1ULL << MCID::PreISelOpcode); }
/// Return true if this instruction can have a variable number of
/// operands. In this case, the variable operands will be after the normal
/// operands but before the implicit definitions and uses (if any are
/// present).
bool isVariadic() const { return Flags & (1ULL << MCID::Variadic); }
/// Set if this instruction has an optional definition, e.g.
/// ARM instructions which can set condition code if 's' bit is set.
bool hasOptionalDef() const { return Flags & (1ULL << MCID::HasOptionalDef); }
/// Return true if this is a pseudo instruction that doesn't
/// correspond to a real machine instruction.
bool isPseudo() const { return Flags & (1ULL << MCID::Pseudo); }
/// Return true if the instruction is a return.
bool isReturn() const { return Flags & (1ULL << MCID::Return); }
/// Return true if the instruction is an add instruction.
bool isAdd() const { return Flags & (1ULL << MCID::Add); }
/// Return true if this instruction is a trap.
bool isTrap() const { return Flags & (1ULL << MCID::Trap); }
/// Return true if the instruction is a register to register move.
bool isMoveReg() const { return Flags & (1ULL << MCID::MoveReg); }
/// Return true if the instruction is a call.
bool isCall() const { return Flags & (1ULL << MCID::Call); }
/// Returns true if the specified instruction stops control flow
/// from executing the instruction immediately following it. Examples include
/// unconditional branches and return instructions.
bool isBarrier() const { return Flags & (1ULL << MCID::Barrier); }
/// Returns true if this instruction part of the terminator for
/// a basic block. Typically this is things like return and branch
/// instructions.
///
/// Various passes use this to insert code into the bottom of a basic block,
/// but before control flow occurs.
bool isTerminator() const { return Flags & (1ULL << MCID::Terminator); }
/// Returns true if this is a conditional, unconditional, or
/// indirect branch. Predicates below can be used to discriminate between
/// these cases, and the TargetInstrInfo::analyzeBranch method can be used to
/// get more information.
bool isBranch() const { return Flags & (1ULL << MCID::Branch); }
/// Return true if this is an indirect branch, such as a
/// branch through a register.
bool isIndirectBranch() const { return Flags & (1ULL << MCID::IndirectBranch); }
/// Return true if this is a branch which may fall
/// through to the next instruction or may transfer control flow to some other
/// block. The TargetInstrInfo::analyzeBranch method can be used to get more
/// information about this branch.
bool isConditionalBranch() const {
return isBranch() && !isBarrier() && !isIndirectBranch();
}
/// Return true if this is a branch which always
/// transfers control flow to some other block. The
/// TargetInstrInfo::analyzeBranch method can be used to get more information
/// about this branch.
bool isUnconditionalBranch() const {
return isBranch() && isBarrier() && !isIndirectBranch();
}
/// Return true if this is a branch or an instruction which directly
/// writes to the program counter. Considered 'may' affect rather than
/// 'does' affect as things like predication are not taken into account.
bool mayAffectControlFlow(const MCInst &MI, const MCRegisterInfo &RI) const;
/// Return true if this instruction has a predicate operand
/// that controls execution. It may be set to 'always', or may be set to other
/// values. There are various methods in TargetInstrInfo that can be used to
/// control and modify the predicate in this instruction.
bool isPredicable() const { return Flags & (1ULL << MCID::Predicable); }
/// Return true if this instruction is a comparison.
bool isCompare() const { return Flags & (1ULL << MCID::Compare); }
/// Return true if this instruction is a move immediate
/// (including conditional moves) instruction.
bool isMoveImmediate() const { return Flags & (1ULL << MCID::MoveImm); }
/// Return true if this instruction is a bitcast instruction.
bool isBitcast() const { return Flags & (1ULL << MCID::Bitcast); }
/// Return true if this is a select instruction.
bool isSelect() const { return Flags & (1ULL << MCID::Select); }
/// Return true if this instruction cannot be safely
/// duplicated. For example, if the instruction has a unique labels attached
/// to it, duplicating it would cause multiple definition errors.
bool isNotDuplicable() const { return Flags & (1ULL << MCID::NotDuplicable); }
/// Returns true if the specified instruction has a delay slot which
/// must be filled by the code generator.
bool hasDelaySlot() const { return Flags & (1ULL << MCID::DelaySlot); }
/// Return true for instructions that can be folded as memory operands
/// in other instructions. The most common use for this is instructions that
/// are simple loads from memory that don't modify the loaded value in any
/// way, but it can also be used for instructions that can be expressed as
/// constant-pool loads, such as V_SETALLONES on x86, to allow them to be
/// folded when it is beneficial. This should only be set on instructions
/// that return a value in their only virtual register definition.
bool canFoldAsLoad() const { return Flags & (1ULL << MCID::FoldableAsLoad); }
/// Return true if this instruction behaves
/// the same way as the generic REG_SEQUENCE instructions.
/// E.g., on ARM,
/// dX VMOVDRR rY, rZ
/// is equivalent to
/// dX = REG_SEQUENCE rY, ssub_0, rZ, ssub_1.
///
/// Note that for the optimizers to be able to take advantage of
/// this property, TargetInstrInfo::getRegSequenceLikeInputs has to be
/// override accordingly.
bool isRegSequenceLike() const { return Flags & (1ULL << MCID::RegSequence); }
/// Return true if this instruction behaves
/// the same way as the generic EXTRACT_SUBREG instructions.
/// E.g., on ARM,
/// rX, rY VMOVRRD dZ
/// is equivalent to two EXTRACT_SUBREG:
/// rX = EXTRACT_SUBREG dZ, ssub_0
/// rY = EXTRACT_SUBREG dZ, ssub_1
///
/// Note that for the optimizers to be able to take advantage of
/// this property, TargetInstrInfo::getExtractSubregLikeInputs has to be
/// override accordingly.
bool isExtractSubregLike() const {
return Flags & (1ULL << MCID::ExtractSubreg);
}
/// Return true if this instruction behaves
/// the same way as the generic INSERT_SUBREG instructions.
/// E.g., on ARM,
/// dX = VSETLNi32 dY, rZ, Imm
/// is equivalent to a INSERT_SUBREG:
/// dX = INSERT_SUBREG dY, rZ, translateImmToSubIdx(Imm)
///
/// Note that for the optimizers to be able to take advantage of
/// this property, TargetInstrInfo::getInsertSubregLikeInputs has to be
/// override accordingly.
bool isInsertSubregLike() const { return Flags & (1ULL << MCID::InsertSubreg); }
/// Return true if this instruction is convergent.
///
/// Convergent instructions may not be made control-dependent on any
/// additional values.
bool isConvergent() const { return Flags & (1ULL << MCID::Convergent); }
/// Return true if variadic operands of this instruction are definitions.
bool variadicOpsAreDefs() const {
return Flags & (1ULL << MCID::VariadicOpsAreDefs);
}
/// Return true if this instruction authenticates a pointer (e.g. LDRAx/BRAx
/// from ARMv8.3, which perform loads/branches with authentication).
///
/// An authenticated instruction may fail in an ABI-defined manner when
/// operating on an invalid signed pointer.
bool isAuthenticated() const {
return Flags & (1ULL << MCID::Authenticated);
}
//===--------------------------------------------------------------------===//
// Side Effect Analysis
//===--------------------------------------------------------------------===//
/// Return true if this instruction could possibly read memory.
/// Instructions with this flag set are not necessarily simple load
/// instructions, they may load a value and modify it, for example.
bool mayLoad() const { return Flags & (1ULL << MCID::MayLoad); }
/// Return true if this instruction could possibly modify memory.
/// Instructions with this flag set are not necessarily simple store
/// instructions, they may store a modified value based on their operands, or
/// may not actually modify anything, for example.
bool mayStore() const { return Flags & (1ULL << MCID::MayStore); }
/// Return true if this instruction may raise a floating-point exception.
bool mayRaiseFPException() const {
return Flags & (1ULL << MCID::MayRaiseFPException);
}
/// Return true if this instruction has side
/// effects that are not modeled by other flags. This does not return true
/// for instructions whose effects are captured by:
///
/// 1. Their operand list and implicit definition/use list. Register use/def
/// info is explicit for instructions.
/// 2. Memory accesses. Use mayLoad/mayStore.
/// 3. Calling, branching, returning: use isCall/isReturn/isBranch.
///
/// Examples of side effects would be modifying 'invisible' machine state like
/// a control register, flushing a cache, modifying a register invisible to
/// LLVM, etc.
bool hasUnmodeledSideEffects() const {
return Flags & (1ULL << MCID::UnmodeledSideEffects);
}
//===--------------------------------------------------------------------===//
// Flags that indicate whether an instruction can be modified by a method.
//===--------------------------------------------------------------------===//
/// Return true if this may be a 2- or 3-address instruction (of the
/// form "X = op Y, Z, ..."), which produces the same result if Y and Z are
/// exchanged. If this flag is set, then the
/// TargetInstrInfo::commuteInstruction method may be used to hack on the
/// instruction.
///
/// Note that this flag may be set on instructions that are only commutable
/// sometimes. In these cases, the call to commuteInstruction will fail.
/// Also note that some instructions require non-trivial modification to
/// commute them.
bool isCommutable() const { return Flags & (1ULL << MCID::Commutable); }
/// Return true if this is a 2-address instruction which can be changed
/// into a 3-address instruction if needed. Doing this transformation can be
/// profitable in the register allocator, because it means that the
/// instruction can use a 2-address form if possible, but degrade into a less
/// efficient form if the source and dest register cannot be assigned to the
/// same register. For example, this allows the x86 backend to turn a "shl
/// reg, 3" instruction into an LEA instruction, which is the same speed as
/// the shift but has bigger code size.
///
/// If this returns true, then the target must implement the
/// TargetInstrInfo::convertToThreeAddress method for this instruction, which
/// is allowed to fail if the transformation isn't valid for this specific
/// instruction (e.g. shl reg, 4 on x86).
///
bool isConvertibleTo3Addr() const {
return Flags & (1ULL << MCID::ConvertibleTo3Addr);
}
/// Return true if this instruction requires custom insertion support
/// when the DAG scheduler is inserting it into a machine basic block. If
/// this is true for the instruction, it basically means that it is a pseudo
/// instruction used at SelectionDAG time that is expanded out into magic code
/// by the target when MachineInstrs are formed.
///
/// If this is true, the TargetLoweringInfo::InsertAtEndOfBasicBlock method
/// is used to insert this into the MachineBasicBlock.
bool usesCustomInsertionHook() const {
return Flags & (1ULL << MCID::UsesCustomInserter);
}
/// Return true if this instruction requires *adjustment* after
/// instruction selection by calling a target hook. For example, this can be
/// used to fill in ARM 's' optional operand depending on whether the
/// conditional flag register is used.
bool hasPostISelHook() const { return Flags & (1ULL << MCID::HasPostISelHook); }
/// Returns true if this instruction is a candidate for remat. This
/// flag is only used in TargetInstrInfo method isTriviallyRematerializable.
///
/// If this flag is set, the isReallyTriviallyReMaterializable()
/// or isReallyTriviallyReMaterializableGeneric methods are called to verify
/// the instruction is really rematable.
bool isRematerializable() const {
return Flags & (1ULL << MCID::Rematerializable);
}
/// Returns true if this instruction has the same cost (or less) than a
/// move instruction. This is useful during certain types of optimizations
/// (e.g., remat during two-address conversion or machine licm) where we would
/// like to remat or hoist the instruction, but not if it costs more than
/// moving the instruction into the appropriate register. Note, we are not
/// marking copies from and to the same register class with this flag.
///
/// This method could be called by interface TargetInstrInfo::isAsCheapAsAMove
/// for different subtargets.
bool isAsCheapAsAMove() const { return Flags & (1ULL << MCID::CheapAsAMove); }
/// Returns true if this instruction source operands have special
/// register allocation requirements that are not captured by the operand
/// register classes. e.g. ARM::STRD's two source registers must be an even /
/// odd pair, ARM::STM registers have to be in ascending order. Post-register
/// allocation passes should not attempt to change allocations for sources of
/// instructions with this flag.
bool hasExtraSrcRegAllocReq() const {
return Flags & (1ULL << MCID::ExtraSrcRegAllocReq);
}
/// Returns true if this instruction def operands have special register
/// allocation requirements that are not captured by the operand register
/// classes. e.g. ARM::LDRD's two def registers must be an even / odd pair,
/// ARM::LDM registers have to be in ascending order. Post-register
/// allocation passes should not attempt to change allocations for definitions
/// of instructions with this flag.
bool hasExtraDefRegAllocReq() const {
return Flags & (1ULL << MCID::ExtraDefRegAllocReq);
}
/// Return a list of registers that are potentially read by any
/// instance of this machine instruction. For example, on X86, the "adc"
/// instruction adds two register operands and adds the carry bit in from the
/// flags register. In this case, the instruction is marked as implicitly
/// reading the flags. Likewise, the variable shift instruction on X86 is
/// marked as implicitly reading the 'CL' register, which it always does.
///
/// This method returns null if the instruction has no implicit uses.
const MCPhysReg *getImplicitUses() const { return ImplicitUses; }
/// Return the number of implicit uses this instruction has.
unsigned getNumImplicitUses() const {
if (!ImplicitUses)
return 0;
unsigned i = 0;
for (; ImplicitUses[i]; ++i) /*empty*/
;
return i;
}
/// Return a list of registers that are potentially written by any
/// instance of this machine instruction. For example, on X86, many
/// instructions implicitly set the flags register. In this case, they are
/// marked as setting the FLAGS. Likewise, many instructions always deposit
/// their result in a physical register. For example, the X86 divide
/// instruction always deposits the quotient and remainder in the EAX/EDX
/// registers. For that instruction, this will return a list containing the
/// EAX/EDX/EFLAGS registers.
///
/// This method returns null if the instruction has no implicit defs.
const MCPhysReg *getImplicitDefs() const { return ImplicitDefs; }
/// Return the number of implicit defs this instruct has.
unsigned getNumImplicitDefs() const {
if (!ImplicitDefs)
return 0;
unsigned i = 0;
for (; ImplicitDefs[i]; ++i) /*empty*/
;
return i;
}
/// Return true if this instruction implicitly
/// uses the specified physical register.
bool hasImplicitUseOfPhysReg(unsigned Reg) const {
if (const MCPhysReg *ImpUses = ImplicitUses)
for (; *ImpUses; ++ImpUses)
if (*ImpUses == Reg)
return true;
return false;
}
/// Return true if this instruction implicitly
/// defines the specified physical register.
bool hasImplicitDefOfPhysReg(unsigned Reg,
const MCRegisterInfo *MRI = nullptr) const;
/// Return the scheduling class for this instruction. The
/// scheduling class is an index into the InstrItineraryData table. This
/// returns zero if there is no known scheduling information for the
/// instruction.
unsigned getSchedClass() const { return SchedClass; }
/// Return the number of bytes in the encoding of this instruction,
/// or zero if the encoding size cannot be known from the opcode.
unsigned getSize() const { return Size; }
/// Find the index of the first operand in the
/// operand list that is used to represent the predicate. It returns -1 if
/// none is found.
int findFirstPredOperandIdx() const {
if (isPredicable()) {
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
if (OpInfo[i].isPredicate())
return i;
}
return -1;
}
/// Return true if this instruction defines the specified physical
/// register, either explicitly or implicitly.
bool hasDefOfPhysReg(const MCInst &MI, unsigned Reg,
const MCRegisterInfo &RI) const;
};
} // end namespace llvm
#endif
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif
|