1//===-- SIRegisterInfo.h - SI Register Info Interface ----------*- 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/// \file
10/// Interface definition for SIRegisterInfo
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_LIB_TARGET_AMDGPU_SIREGISTERINFO_H
15#define LLVM_LIB_TARGET_AMDGPU_SIREGISTERINFO_H
16
17#include "llvm/ADT/BitVector.h"
18
19#define GET_REGINFO_HEADER
20#include "AMDGPUGenRegisterInfo.inc"
21
22#include "SIDefines.h"
23
24namespace llvm {
25
26class GCNSubtarget;
27class LiveIntervals;
28class LiveRegUnits;
29class RegisterBank;
30struct SGPRSpillBuilder;
31
32class SIRegisterInfo final : public AMDGPUGenRegisterInfo {
33private:
34 const GCNSubtarget &ST;
35 bool SpillSGPRToVGPR;
36 bool isWave32;
37 BitVector RegPressureIgnoredUnits;
38
39 /// Sub reg indexes for getRegSplitParts.
40 /// First index represents subreg size from 1 to 16 DWORDs.
41 /// The inner vector is sorted by bit offset.
42 /// Provided a register can be fully split with given subregs,
43 /// all elements of the inner vector combined give a full lane mask.
44 static std::array<std::vector<int16_t>, 16> RegSplitParts;
45
46 // Table representing sub reg of given width and offset.
47 // First index is subreg size: 32, 64, 96, 128, 160, 192, 224, 256, 512.
48 // Second index is 32 different dword offsets.
49 static std::array<std::array<uint16_t, 32>, 9> SubRegFromChannelTable;
50
51 void reserveRegisterTuples(BitVector &, MCRegister Reg) const;
52
53public:
54 SIRegisterInfo(const GCNSubtarget &ST);
55
56 struct SpilledReg {
57 Register VGPR;
58 int Lane = -1;
59
60 SpilledReg() = default;
61 SpilledReg(Register R, int L) : VGPR(R), Lane(L) {}
62
63 bool hasLane() { return Lane != -1; }
64 bool hasReg() { return VGPR != 0; }
65 };
66
67 /// \returns the sub reg enum value for the given \p Channel
68 /// (e.g. getSubRegFromChannel(0) -> AMDGPU::sub0)
69 static unsigned getSubRegFromChannel(unsigned Channel, unsigned NumRegs = 1);
70
71 bool spillSGPRToVGPR() const {
72 return SpillSGPRToVGPR;
73 }
74
75 /// Return the largest available SGPR aligned to \p Align for the register
76 /// class \p RC.
77 MCRegister getAlignedHighSGPRForRC(const MachineFunction &MF,
78 const unsigned Align,
79 const TargetRegisterClass *RC) const;
80
81 /// Return the end register initially reserved for the scratch buffer in case
82 /// spilling is needed.
83 MCRegister reservedPrivateSegmentBufferReg(const MachineFunction &MF) const;
84
85 BitVector getReservedRegs(const MachineFunction &MF) const override;
86 bool isAsmClobberable(const MachineFunction &MF,
87 MCRegister PhysReg) const override;
88
89 const MCPhysReg *getCalleeSavedRegs(const MachineFunction *MF) const override;
90 const MCPhysReg *getCalleeSavedRegsViaCopy(const MachineFunction *MF) const;
91 const uint32_t *getCallPreservedMask(const MachineFunction &MF,
92 CallingConv::ID) const override;
93 const uint32_t *getNoPreservedMask() const override;
94
95 // Functions with the amdgpu_cs_chain or amdgpu_cs_chain_preserve calling
96 // conventions are free to use certain VGPRs without saving and restoring any
97 // lanes (not even inactive ones).
98 static bool isChainScratchRegister(Register VGPR);
99
100 // Stack access is very expensive. CSRs are also the high registers, and we
101 // want to minimize the number of used registers.
102 unsigned getCSRFirstUseCost() const override {
103 return 100;
104 }
105
106 const TargetRegisterClass *
107 getLargestLegalSuperClass(const TargetRegisterClass *RC,
108 const MachineFunction &MF) const override;
109
110 Register getFrameRegister(const MachineFunction &MF) const override;
111
112 bool hasBasePointer(const MachineFunction &MF) const;
113 Register getBaseRegister() const;
114
115 bool shouldRealignStack(const MachineFunction &MF) const override;
116 bool requiresRegisterScavenging(const MachineFunction &Fn) const override;
117
118 bool requiresFrameIndexScavenging(const MachineFunction &MF) const override;
119 bool requiresFrameIndexReplacementScavenging(
120 const MachineFunction &MF) const override;
121 bool requiresVirtualBaseRegisters(const MachineFunction &Fn) const override;
122
123 int64_t getScratchInstrOffset(const MachineInstr *MI) const;
124
125 int64_t getFrameIndexInstrOffset(const MachineInstr *MI,
126 int Idx) const override;
127
128 bool needsFrameBaseReg(MachineInstr *MI, int64_t Offset) const override;
129
130 Register materializeFrameBaseRegister(MachineBasicBlock *MBB, int FrameIdx,
131 int64_t Offset) const override;
132
133 void resolveFrameIndex(MachineInstr &MI, Register BaseReg,
134 int64_t Offset) const override;
135
136 bool isFrameOffsetLegal(const MachineInstr *MI, Register BaseReg,
137 int64_t Offset) const override;
138
139 const TargetRegisterClass *getPointerRegClass(
140 const MachineFunction &MF, unsigned Kind = 0) const override;
141
142 /// Returns a legal register class to copy a register in the specified class
143 /// to or from. If it is possible to copy the register directly without using
144 /// a cross register class copy, return the specified RC. Returns NULL if it
145 /// is not possible to copy between two registers of the specified class.
146 const TargetRegisterClass *
147 getCrossCopyRegClass(const TargetRegisterClass *RC) const override;
148
149 void buildVGPRSpillLoadStore(SGPRSpillBuilder &SB, int Index, int Offset,
150 bool IsLoad, bool IsKill = true) const;
151
152 /// If \p OnlyToVGPR is true, this will only succeed if this manages to find a
153 /// free VGPR lane to spill.
154 bool spillSGPR(MachineBasicBlock::iterator MI, int FI, RegScavenger *RS,
155 SlotIndexes *Indexes = nullptr, LiveIntervals *LIS = nullptr,
156 bool OnlyToVGPR = false,
157 bool SpillToPhysVGPRLane = false) const;
158
159 bool restoreSGPR(MachineBasicBlock::iterator MI, int FI, RegScavenger *RS,
160 SlotIndexes *Indexes = nullptr, LiveIntervals *LIS = nullptr,
161 bool OnlyToVGPR = false,
162 bool SpillToPhysVGPRLane = false) const;
163
164 bool spillEmergencySGPR(MachineBasicBlock::iterator MI,
165 MachineBasicBlock &RestoreMBB, Register SGPR,
166 RegScavenger *RS) const;
167
168 bool eliminateFrameIndex(MachineBasicBlock::iterator MI, int SPAdj,
169 unsigned FIOperandNum,
170 RegScavenger *RS) const override;
171
172 bool eliminateSGPRToVGPRSpillFrameIndex(
173 MachineBasicBlock::iterator MI, int FI, RegScavenger *RS,
174 SlotIndexes *Indexes = nullptr, LiveIntervals *LIS = nullptr,
175 bool SpillToPhysVGPRLane = false) const;
176
177 StringRef getRegAsmName(MCRegister Reg) const override;
178
179 // Pseudo regs are not allowed
180 unsigned getHWRegIndex(MCRegister Reg) const {
181 return getEncodingValue(RegNo: Reg) & 0xff;
182 }
183
184 LLVM_READONLY
185 const TargetRegisterClass *getVGPRClassForBitWidth(unsigned BitWidth) const;
186
187 LLVM_READONLY
188 const TargetRegisterClass *getAGPRClassForBitWidth(unsigned BitWidth) const;
189
190 LLVM_READONLY
191 const TargetRegisterClass *
192 getVectorSuperClassForBitWidth(unsigned BitWidth) const;
193
194 LLVM_READONLY
195 static const TargetRegisterClass *getSGPRClassForBitWidth(unsigned BitWidth);
196
197 /// \returns true if this class contains only SGPR registers
198 static bool isSGPRClass(const TargetRegisterClass *RC) {
199 return hasSGPRs(RC) && !hasVGPRs(RC) && !hasAGPRs(RC);
200 }
201
202 /// \returns true if this class ID contains only SGPR registers
203 bool isSGPRClassID(unsigned RCID) const {
204 return isSGPRClass(RC: getRegClass(RCID));
205 }
206
207 bool isSGPRReg(const MachineRegisterInfo &MRI, Register Reg) const;
208
209 /// \returns true if this class contains only VGPR registers
210 static bool isVGPRClass(const TargetRegisterClass *RC) {
211 return hasVGPRs(RC) && !hasAGPRs(RC) && !hasSGPRs(RC);
212 }
213
214 /// \returns true if this class contains only AGPR registers
215 static bool isAGPRClass(const TargetRegisterClass *RC) {
216 return hasAGPRs(RC) && !hasVGPRs(RC) && !hasSGPRs(RC);
217 }
218
219 /// \returns true only if this class contains both VGPR and AGPR registers
220 bool isVectorSuperClass(const TargetRegisterClass *RC) const {
221 return hasVGPRs(RC) && hasAGPRs(RC) && !hasSGPRs(RC);
222 }
223
224 /// \returns true only if this class contains both VGPR and SGPR registers
225 bool isVSSuperClass(const TargetRegisterClass *RC) const {
226 return hasVGPRs(RC) && hasSGPRs(RC) && !hasAGPRs(RC);
227 }
228
229 /// \returns true if this class contains VGPR registers.
230 static bool hasVGPRs(const TargetRegisterClass *RC) {
231 return RC->TSFlags & SIRCFlags::HasVGPR;
232 }
233
234 /// \returns true if this class contains AGPR registers.
235 static bool hasAGPRs(const TargetRegisterClass *RC) {
236 return RC->TSFlags & SIRCFlags::HasAGPR;
237 }
238
239 /// \returns true if this class contains SGPR registers.
240 static bool hasSGPRs(const TargetRegisterClass *RC) {
241 return RC->TSFlags & SIRCFlags::HasSGPR;
242 }
243
244 /// \returns true if this class contains any vector registers.
245 static bool hasVectorRegisters(const TargetRegisterClass *RC) {
246 return hasVGPRs(RC) || hasAGPRs(RC);
247 }
248
249 /// \returns A VGPR reg class with the same width as \p SRC
250 const TargetRegisterClass *
251 getEquivalentVGPRClass(const TargetRegisterClass *SRC) const;
252
253 /// \returns An AGPR reg class with the same width as \p SRC
254 const TargetRegisterClass *
255 getEquivalentAGPRClass(const TargetRegisterClass *SRC) const;
256
257 /// \returns A SGPR reg class with the same width as \p SRC
258 const TargetRegisterClass *
259 getEquivalentSGPRClass(const TargetRegisterClass *VRC) const;
260
261 /// Returns a register class which is compatible with \p SuperRC, such that a
262 /// subregister exists with class \p SubRC with subregister index \p
263 /// SubIdx. If this is impossible (e.g., an unaligned subregister index within
264 /// a register tuple), return null.
265 const TargetRegisterClass *
266 getCompatibleSubRegClass(const TargetRegisterClass *SuperRC,
267 const TargetRegisterClass *SubRC,
268 unsigned SubIdx) const;
269
270 bool shouldRewriteCopySrc(const TargetRegisterClass *DefRC,
271 unsigned DefSubReg,
272 const TargetRegisterClass *SrcRC,
273 unsigned SrcSubReg) const override;
274
275 /// \returns True if operands defined with this operand type can accept
276 /// a literal constant (i.e. any 32-bit immediate).
277 bool opCanUseLiteralConstant(unsigned OpType) const;
278
279 /// \returns True if operands defined with this operand type can accept
280 /// an inline constant. i.e. An integer value in the range (-16, 64) or
281 /// -4.0f, -2.0f, -1.0f, -0.5f, 0.0f, 0.5f, 1.0f, 2.0f, 4.0f.
282 bool opCanUseInlineConstant(unsigned OpType) const;
283
284 MCRegister findUnusedRegister(const MachineRegisterInfo &MRI,
285 const TargetRegisterClass *RC,
286 const MachineFunction &MF,
287 bool ReserveHighestVGPR = false) const;
288
289 const TargetRegisterClass *getRegClassForReg(const MachineRegisterInfo &MRI,
290 Register Reg) const;
291 const TargetRegisterClass *
292 getRegClassForOperandReg(const MachineRegisterInfo &MRI,
293 const MachineOperand &MO) const;
294
295 bool isVGPR(const MachineRegisterInfo &MRI, Register Reg) const;
296 bool isAGPR(const MachineRegisterInfo &MRI, Register Reg) const;
297 bool isVectorRegister(const MachineRegisterInfo &MRI, Register Reg) const {
298 return isVGPR(MRI, Reg) || isAGPR(MRI, Reg);
299 }
300
301 // FIXME: SGPRs are assumed to be uniform, but this is not true for i1 SGPRs
302 // (such as VCC) which hold a wave-wide vector of boolean values. Examining
303 // just the register class is not suffcient; it needs to be combined with a
304 // value type. The next predicate isUniformReg() does this correctly.
305 bool isDivergentRegClass(const TargetRegisterClass *RC) const override {
306 return !isSGPRClass(RC);
307 }
308
309 bool isUniformReg(const MachineRegisterInfo &MRI, const RegisterBankInfo &RBI,
310 Register Reg) const override;
311
312 ArrayRef<int16_t> getRegSplitParts(const TargetRegisterClass *RC,
313 unsigned EltSize) const;
314
315 bool shouldCoalesce(MachineInstr *MI,
316 const TargetRegisterClass *SrcRC,
317 unsigned SubReg,
318 const TargetRegisterClass *DstRC,
319 unsigned DstSubReg,
320 const TargetRegisterClass *NewRC,
321 LiveIntervals &LIS) const override;
322
323 unsigned getRegPressureLimit(const TargetRegisterClass *RC,
324 MachineFunction &MF) const override;
325
326 unsigned getRegPressureSetLimit(const MachineFunction &MF,
327 unsigned Idx) const override;
328
329 const int *getRegUnitPressureSets(unsigned RegUnit) const override;
330
331 MCRegister getReturnAddressReg(const MachineFunction &MF) const;
332
333 const TargetRegisterClass *
334 getRegClassForSizeOnBank(unsigned Size, const RegisterBank &Bank) const;
335
336 const TargetRegisterClass *
337 getRegClassForTypeOnBank(LLT Ty, const RegisterBank &Bank) const {
338 return getRegClassForSizeOnBank(Size: Ty.getSizeInBits(), Bank);
339 }
340
341 const TargetRegisterClass *
342 getConstrainedRegClassForOperand(const MachineOperand &MO,
343 const MachineRegisterInfo &MRI) const override;
344
345 const TargetRegisterClass *getBoolRC() const {
346 return isWave32 ? &AMDGPU::SReg_32RegClass
347 : &AMDGPU::SReg_64RegClass;
348 }
349
350 const TargetRegisterClass *getWaveMaskRegClass() const {
351 return isWave32 ? &AMDGPU::SReg_32_XM0_XEXECRegClass
352 : &AMDGPU::SReg_64_XEXECRegClass;
353 }
354
355 // Return the appropriate register class to use for 64-bit VGPRs for the
356 // subtarget.
357 const TargetRegisterClass *getVGPR64Class() const;
358
359 MCRegister getVCC() const;
360
361 MCRegister getExec() const;
362
363 const TargetRegisterClass *getRegClass(unsigned RCID) const;
364
365 // Find reaching register definition
366 MachineInstr *findReachingDef(Register Reg, unsigned SubReg,
367 MachineInstr &Use,
368 MachineRegisterInfo &MRI,
369 LiveIntervals *LIS) const;
370
371 const uint32_t *getAllVGPRRegMask() const;
372 const uint32_t *getAllAGPRRegMask() const;
373 const uint32_t *getAllVectorRegMask() const;
374 const uint32_t *getAllAllocatableSRegMask() const;
375
376 // \returns number of 32 bit registers covered by a \p LM
377 static unsigned getNumCoveredRegs(LaneBitmask LM) {
378 // The assumption is that every lo16 subreg is an even bit and every hi16
379 // is an adjacent odd bit or vice versa.
380 uint64_t Mask = LM.getAsInteger();
381 uint64_t Even = Mask & 0xAAAAAAAAAAAAAAAAULL;
382 Mask = (Even >> 1) | Mask;
383 uint64_t Odd = Mask & 0x5555555555555555ULL;
384 return llvm::popcount(Value: Odd);
385 }
386
387 // \returns a DWORD offset of a \p SubReg
388 unsigned getChannelFromSubReg(unsigned SubReg) const {
389 return SubReg ? (getSubRegIdxOffset(Idx: SubReg) + 31) / 32 : 0;
390 }
391
392 // \returns a DWORD size of a \p SubReg
393 unsigned getNumChannelsFromSubReg(unsigned SubReg) const {
394 return getNumCoveredRegs(LM: getSubRegIndexLaneMask(SubIdx: SubReg));
395 }
396
397 // For a given 16 bit \p Reg \returns a 32 bit register holding it.
398 // \returns \p Reg otherwise.
399 MCPhysReg get32BitRegister(MCPhysReg Reg) const;
400
401 // Returns true if a given register class is properly aligned for
402 // the subtarget.
403 bool isProperlyAlignedRC(const TargetRegisterClass &RC) const;
404
405 // Given \p RC returns corresponding aligned register class if required
406 // by the subtarget.
407 const TargetRegisterClass *
408 getProperlyAlignedRC(const TargetRegisterClass *RC) const;
409
410 /// Return all SGPR128 which satisfy the waves per execution unit requirement
411 /// of the subtarget.
412 ArrayRef<MCPhysReg> getAllSGPR128(const MachineFunction &MF) const;
413
414 /// Return all SGPR64 which satisfy the waves per execution unit requirement
415 /// of the subtarget.
416 ArrayRef<MCPhysReg> getAllSGPR64(const MachineFunction &MF) const;
417
418 /// Return all SGPR32 which satisfy the waves per execution unit requirement
419 /// of the subtarget.
420 ArrayRef<MCPhysReg> getAllSGPR32(const MachineFunction &MF) const;
421
422 // Insert spill or restore instructions.
423 // When lowering spill pseudos, the RegScavenger should be set.
424 // For creating spill instructions during frame lowering, where no scavenger
425 // is available, LiveUnits can be used.
426 void buildSpillLoadStore(MachineBasicBlock &MBB,
427 MachineBasicBlock::iterator MI, const DebugLoc &DL,
428 unsigned LoadStoreOp, int Index, Register ValueReg,
429 bool ValueIsKill, MCRegister ScratchOffsetReg,
430 int64_t InstrOffset, MachineMemOperand *MMO,
431 RegScavenger *RS,
432 LiveRegUnits *LiveUnits = nullptr) const;
433
434 // Return alignment in register file of first register in a register tuple.
435 unsigned getRegClassAlignmentNumBits(const TargetRegisterClass *RC) const {
436 return (RC->TSFlags & SIRCFlags::RegTupleAlignUnitsMask) * 32;
437 }
438
439 // Check if register class RC has required alignment.
440 bool isRegClassAligned(const TargetRegisterClass *RC,
441 unsigned AlignNumBits) const {
442 assert(AlignNumBits != 0);
443 unsigned RCAlign = getRegClassAlignmentNumBits(RC);
444 return RCAlign == AlignNumBits ||
445 (RCAlign > AlignNumBits && (RCAlign % AlignNumBits) == 0);
446 }
447
448 // Return alignment of a SubReg relative to start of a register in RC class.
449 // No check if the subreg is supported by the current RC is made.
450 unsigned getSubRegAlignmentNumBits(const TargetRegisterClass *RC,
451 unsigned SubReg) const;
452};
453
454namespace AMDGPU {
455/// Get the size in bits of a register from the register class \p RC.
456unsigned getRegBitWidth(const TargetRegisterClass &RC);
457} // namespace AMDGPU
458
459} // End namespace llvm
460
461#endif
462