1//===-- HexagonRegisterInfo.cpp - Hexagon Register Information ------------===//
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 contains the Hexagon implementation of the TargetRegisterInfo
10// class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "HexagonRegisterInfo.h"
15#include "Hexagon.h"
16#include "HexagonMachineFunctionInfo.h"
17#include "HexagonSubtarget.h"
18#include "HexagonTargetMachine.h"
19#include "llvm/ADT/BitVector.h"
20#include "llvm/ADT/SmallSet.h"
21#include "llvm/ADT/STLExtras.h"
22#include "llvm/CodeGen/LiveIntervals.h"
23#include "llvm/CodeGen/LiveRegUnits.h"
24#include "llvm/CodeGen/MachineFrameInfo.h"
25#include "llvm/CodeGen/MachineFunction.h"
26#include "llvm/CodeGen/MachineFunctionPass.h"
27#include "llvm/CodeGen/MachineInstrBuilder.h"
28#include "llvm/CodeGen/MachineRegisterInfo.h"
29#include "llvm/CodeGen/PseudoSourceValue.h"
30#include "llvm/CodeGen/RegisterScavenging.h"
31#include "llvm/CodeGen/TargetInstrInfo.h"
32#include "llvm/IR/Function.h"
33#include "llvm/IR/Type.h"
34#include "llvm/MC/MachineLocation.h"
35#include "llvm/Support/CommandLine.h"
36#include "llvm/Support/Debug.h"
37#include "llvm/Support/ErrorHandling.h"
38#include "llvm/Support/raw_ostream.h"
39#include "llvm/Target/TargetMachine.h"
40#include "llvm/Target/TargetOptions.h"
41
42#define GET_REGINFO_TARGET_DESC
43#include "HexagonGenRegisterInfo.inc"
44
45using namespace llvm;
46
47static cl::opt<unsigned> FrameIndexSearchRange(
48 "hexagon-frame-index-search-range", cl::init(32), cl::Hidden,
49 cl::desc("Limit on instruction search range in frame index elimination"));
50
51static cl::opt<unsigned> FrameIndexReuseLimit(
52 "hexagon-frame-index-reuse-limit", cl::init(Val: ~0), cl::Hidden,
53 cl::desc("Limit on the number of reused registers in frame index "
54 "elimination"));
55
56HexagonRegisterInfo::HexagonRegisterInfo(unsigned HwMode)
57 : HexagonGenRegisterInfo(Hexagon::R31, 0/*DwarfFlavor*/, 0/*EHFlavor*/,
58 0/*PC*/, HwMode) {}
59
60
61bool HexagonRegisterInfo::isEHReturnCalleeSaveReg(Register R) const {
62 return R == Hexagon::R0 || R == Hexagon::R1 || R == Hexagon::R2 ||
63 R == Hexagon::R3 || R == Hexagon::D0 || R == Hexagon::D1;
64}
65
66const MCPhysReg *
67HexagonRegisterInfo::getCallerSavedRegs(const MachineFunction *MF,
68 const TargetRegisterClass *RC) const {
69 using namespace Hexagon;
70
71 static const MCPhysReg Int32[] = {
72 R0, R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, 0
73 };
74 static const MCPhysReg Int64[] = {
75 D0, D1, D2, D3, D4, D5, D6, D7, 0
76 };
77 static const MCPhysReg Pred[] = {
78 P0, P1, P2, P3, 0
79 };
80 static const MCPhysReg VecSgl[] = {
81 V0, V1, V2, V3, V4, V5, V6, V7, V8, V9, V10, V11, V12, V13,
82 V14, V15, V16, V17, V18, V19, V20, V21, V22, V23, V24, V25, V26, V27,
83 V28, V29, V30, V31, 0
84 };
85 static const MCPhysReg VecDbl[] = {
86 W0, W1, W2, W3, W4, W5, W6, W7, W8, W9, W10, W11, W12, W13, W14, W15, 0
87 };
88 static const MCPhysReg VecPred[] = {
89 Q0, Q1, Q2, Q3, 0
90 };
91
92 switch (RC->getID()) {
93 case IntRegsRegClassID:
94 return Int32;
95 case DoubleRegsRegClassID:
96 return Int64;
97 case PredRegsRegClassID:
98 return Pred;
99 case HvxVRRegClassID:
100 return VecSgl;
101 case HvxWRRegClassID:
102 return VecDbl;
103 case HvxQRRegClassID:
104 return VecPred;
105 default:
106 break;
107 }
108
109 static const MCPhysReg Empty[] = { 0 };
110#ifndef NDEBUG
111 dbgs() << "Register class: " << getRegClassName(RC) << "\n";
112#endif
113 llvm_unreachable("Unexpected register class");
114 return Empty;
115}
116
117
118const MCPhysReg *
119HexagonRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
120 static const MCPhysReg CalleeSavedRegsV3[] = {
121 Hexagon::R16, Hexagon::R17, Hexagon::R18, Hexagon::R19,
122 Hexagon::R20, Hexagon::R21, Hexagon::R22, Hexagon::R23,
123 Hexagon::R24, Hexagon::R25, Hexagon::R26, Hexagon::R27, 0
124 };
125
126 // Functions that contain a call to __builtin_eh_return also save the first 4
127 // parameter registers.
128 static const MCPhysReg CalleeSavedRegsV3EHReturn[] = {
129 Hexagon::R0, Hexagon::R1, Hexagon::R2, Hexagon::R3,
130 Hexagon::R16, Hexagon::R17, Hexagon::R18, Hexagon::R19,
131 Hexagon::R20, Hexagon::R21, Hexagon::R22, Hexagon::R23,
132 Hexagon::R24, Hexagon::R25, Hexagon::R26, Hexagon::R27, 0
133 };
134
135 bool HasEHReturn = MF->getInfo<HexagonMachineFunctionInfo>()->hasEHReturn();
136
137 return HasEHReturn ? CalleeSavedRegsV3EHReturn : CalleeSavedRegsV3;
138}
139
140
141const uint32_t *HexagonRegisterInfo::getCallPreservedMask(
142 const MachineFunction &MF, CallingConv::ID) const {
143 return HexagonCSR_RegMask;
144}
145
146
147BitVector HexagonRegisterInfo::getReservedRegs(const MachineFunction &MF)
148 const {
149 BitVector Reserved(getNumRegs());
150 Reserved.set(Hexagon::R29);
151 Reserved.set(Hexagon::R30);
152 Reserved.set(Hexagon::R31);
153 Reserved.set(Hexagon::VTMP);
154
155 // Guest registers.
156 Reserved.set(Hexagon::GELR); // G0
157 Reserved.set(Hexagon::GSR); // G1
158 Reserved.set(Hexagon::GOSP); // G2
159 Reserved.set(Hexagon::G3); // G3
160
161 // Control registers.
162 Reserved.set(Hexagon::SA0); // C0
163 Reserved.set(Hexagon::LC0); // C1
164 Reserved.set(Hexagon::SA1); // C2
165 Reserved.set(Hexagon::LC1); // C3
166 Reserved.set(Hexagon::P3_0); // C4
167 Reserved.set(Hexagon::USR); // C8
168 Reserved.set(Hexagon::PC); // C9
169 Reserved.set(Hexagon::UGP); // C10
170 Reserved.set(Hexagon::GP); // C11
171 Reserved.set(Hexagon::CS0); // C12
172 Reserved.set(Hexagon::CS1); // C13
173 Reserved.set(Hexagon::UPCYCLELO); // C14
174 Reserved.set(Hexagon::UPCYCLEHI); // C15
175 Reserved.set(Hexagon::FRAMELIMIT); // C16
176 Reserved.set(Hexagon::FRAMEKEY); // C17
177 Reserved.set(Hexagon::PKTCOUNTLO); // C18
178 Reserved.set(Hexagon::PKTCOUNTHI); // C19
179 Reserved.set(Hexagon::UTIMERLO); // C30
180 Reserved.set(Hexagon::UTIMERHI); // C31
181 // Out of the control registers, only C8 is explicitly defined in
182 // HexagonRegisterInfo.td. If others are defined, make sure to add
183 // them here as well.
184 Reserved.set(Hexagon::C8);
185 Reserved.set(Hexagon::USR_OVF);
186
187 // Leveraging these registers will require more work to recognize
188 // the new semantics posed, Hi/LoVec patterns, etc.
189 // Note well: if enabled, they should be restricted to only
190 // where `HST.useHVXOps() && HST.hasV67Ops()` is true.
191 for (auto Reg : Hexagon_MC::GetVectRegRev())
192 Reserved.set(Reg);
193
194 if (MF.getSubtarget<HexagonSubtarget>().hasReservedR19())
195 Reserved.set(Hexagon::R19);
196
197 Register AP =
198 MF.getInfo<HexagonMachineFunctionInfo>()->getStackAlignBaseReg();
199 if (AP.isValid())
200 Reserved.set(AP);
201
202 for (int x = Reserved.find_first(); x >= 0; x = Reserved.find_next(Prev: x))
203 markSuperRegs(Reserved, x);
204
205 return Reserved;
206}
207
208bool HexagonRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
209 int SPAdj, unsigned FIOp,
210 RegScavenger *RS) const {
211 static unsigned ReuseCount = 0;
212 //
213 // Hexagon_TODO: Do we need to enforce this for Hexagon?
214 assert(SPAdj == 0 && "Unexpected");
215
216 MachineInstr &MI = *II;
217 MachineBasicBlock &MB = *MI.getParent();
218 MachineFunction &MF = *MB.getParent();
219 auto &HST = MF.getSubtarget<HexagonSubtarget>();
220 auto &HII = *HST.getInstrInfo();
221 auto &HFI = *HST.getFrameLowering();
222
223 Register BP;
224 int FI = MI.getOperand(i: FIOp).getIndex();
225 // Select the base pointer (BP) and calculate the actual offset from BP
226 // to the beginning of the object at index FI.
227 int Offset = HFI.getFrameIndexReference(MF, FI, FrameReg&: BP).getFixed();
228 // Add the offset from the instruction.
229 int RealOffset = Offset + MI.getOperand(i: FIOp+1).getImm();
230
231 unsigned Opc = MI.getOpcode();
232 switch (Opc) {
233 case Hexagon::PS_fia:
234 MI.setDesc(HII.get(Hexagon::A2_addi));
235 MI.getOperand(i: FIOp).ChangeToImmediate(ImmVal: RealOffset);
236 MI.removeOperand(OpNo: FIOp+1);
237 return false;
238 case Hexagon::PS_fi:
239 // Set up the instruction for updating below.
240 MI.setDesc(HII.get(Hexagon::A2_addi));
241 break;
242 }
243
244 if (!HII.isValidOffset(Opc, RealOffset, this)) {
245 // If the offset is not valid, calculate the address in a temporary
246 // register and use it with offset 0.
247 int InstOffset = 0;
248 // The actual base register (BP) is typically shared between many
249 // instructions where frame indices are being replaced. In scalar
250 // instructions the offset range is large, and the need for an extra
251 // add instruction is infrequent. Vector loads/stores, however, have
252 // a much smaller offset range: [-8, 7), or #s4. In those cases it
253 // makes sense to "standardize" the immediate in the "addi" instruction
254 // so that multiple loads/stores could be based on it.
255 bool IsPair = false;
256 switch (MI.getOpcode()) {
257 // All of these instructions have the same format: base+#s4.
258 case Hexagon::PS_vloadrw_ai:
259 case Hexagon::PS_vloadrw_nt_ai:
260 case Hexagon::PS_vstorerw_ai:
261 case Hexagon::PS_vstorerw_nt_ai:
262 IsPair = true;
263 [[fallthrough]];
264 case Hexagon::PS_vloadrv_ai:
265 case Hexagon::PS_vloadrv_nt_ai:
266 case Hexagon::PS_vstorerv_ai:
267 case Hexagon::PS_vstorerv_nt_ai:
268 case Hexagon::V6_vL32b_ai:
269 case Hexagon::V6_vS32b_ai: {
270 unsigned HwLen = HST.getVectorLength();
271 if (RealOffset % HwLen == 0) {
272 int VecOffset = RealOffset / HwLen;
273 // Rewrite the offset as "base + [-8, 7)".
274 VecOffset += 8;
275 // Pairs are expanded into two instructions: make sure that both
276 // can use the same base (i.e. VecOffset+1 is not a different
277 // multiple of 16 than VecOffset).
278 if (!IsPair || (VecOffset + 1) % 16 != 0) {
279 RealOffset = (VecOffset & -16) * HwLen;
280 InstOffset = (VecOffset % 16 - 8) * HwLen;
281 }
282 }
283 }
284 }
285
286 // Search backwards in the block for "Reg = A2_addi BP, RealOffset".
287 // This will give us a chance to avoid creating a new register.
288 Register ReuseBP;
289
290 if (ReuseCount < FrameIndexReuseLimit) {
291 unsigned SearchCount = 0, SearchRange = FrameIndexSearchRange;
292 SmallSet<Register,2> SeenVRegs;
293 bool PassedCall = false;
294 LiveRegUnits Defs(*this), Uses(*this);
295
296 for (auto I = std::next(x: II.getReverse()), E = MB.rend(); I != E; ++I) {
297 if (SearchCount == SearchRange)
298 break;
299 ++SearchCount;
300 const MachineInstr &BI = *I;
301 LiveRegUnits::accumulateUsedDefed(BI, Defs, Uses, this);
302 PassedCall |= BI.isCall();
303 for (const MachineOperand &Op : BI.operands()) {
304 if (SeenVRegs.size() > 1)
305 break;
306 if (Op.isReg() && Op.getReg().isVirtual())
307 SeenVRegs.insert(V: Op.getReg());
308 }
309 if (BI.getOpcode() != Hexagon::A2_addi)
310 continue;
311 if (BI.getOperand(i: 1).getReg() != BP)
312 continue;
313 const auto &Op2 = BI.getOperand(i: 2);
314 if (!Op2.isImm() || Op2.getImm() != RealOffset)
315 continue;
316
317 Register R = BI.getOperand(i: 0).getReg();
318 if (R.isPhysical()) {
319 if (Defs.available(Reg: R))
320 ReuseBP = R;
321 } else if (R.isVirtual()) {
322 // Extending a range of a virtual register can be dangerous,
323 // since the scavenger will need to find a physical register
324 // for it. Avoid extending the range past a function call,
325 // and avoid overlapping it with another virtual register.
326 if (!PassedCall && SeenVRegs.size() <= 1)
327 ReuseBP = R;
328 }
329 break;
330 }
331 if (ReuseBP)
332 ++ReuseCount;
333 }
334
335 auto &MRI = MF.getRegInfo();
336 if (!ReuseBP) {
337 ReuseBP = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
338 const DebugLoc &DL = MI.getDebugLoc();
339 BuildMI(MB, II, DL, HII.get(Hexagon::A2_addi), ReuseBP)
340 .addReg(BP)
341 .addImm(RealOffset);
342 }
343 BP = ReuseBP;
344 RealOffset = InstOffset;
345 }
346
347 MI.getOperand(i: FIOp).ChangeToRegister(Reg: BP, isDef: false, isImp: false, isKill: false);
348 MI.getOperand(i: FIOp+1).ChangeToImmediate(ImmVal: RealOffset);
349 return false;
350}
351
352
353bool HexagonRegisterInfo::shouldCoalesce(MachineInstr *MI,
354 const TargetRegisterClass *SrcRC, unsigned SubReg,
355 const TargetRegisterClass *DstRC, unsigned DstSubReg,
356 const TargetRegisterClass *NewRC, LiveIntervals &LIS) const {
357 // Coalescing will extend the live interval of the destination register.
358 // If the destination register is a vector pair, avoid introducing function
359 // calls into the interval, since it could result in a spilling of a pair
360 // instead of a single vector.
361 MachineFunction &MF = *MI->getParent()->getParent();
362 const HexagonSubtarget &HST = MF.getSubtarget<HexagonSubtarget>();
363 if (!HST.useHVXOps() || NewRC->getID() != Hexagon::HvxWRRegClass.getID())
364 return true;
365 bool SmallSrc = SrcRC->getID() == Hexagon::HvxVRRegClass.getID();
366 bool SmallDst = DstRC->getID() == Hexagon::HvxVRRegClass.getID();
367 if (!SmallSrc && !SmallDst)
368 return true;
369
370 Register DstReg = MI->getOperand(i: 0).getReg();
371 Register SrcReg = MI->getOperand(i: 1).getReg();
372 const SlotIndexes &Indexes = *LIS.getSlotIndexes();
373 auto HasCall = [&Indexes] (const LiveInterval::Segment &S) {
374 for (SlotIndex I = S.start.getBaseIndex(), E = S.end.getBaseIndex();
375 I != E; I = I.getNextIndex()) {
376 if (const MachineInstr *MI = Indexes.getInstructionFromIndex(index: I))
377 if (MI->isCall())
378 return true;
379 }
380 return false;
381 };
382
383 if (SmallSrc == SmallDst) {
384 // Both must be true, because the case for both being false was
385 // checked earlier. Both registers will be coalesced into a register
386 // of a wider class (HvxWR), and we don't want its live range to
387 // span over calls.
388 return !any_of(Range&: LIS.getInterval(Reg: DstReg), P: HasCall) &&
389 !any_of(Range&: LIS.getInterval(Reg: SrcReg), P: HasCall);
390 }
391
392 // If one register is large (HvxWR) and the other is small (HvxVR), then
393 // coalescing is ok if the large is already live across a function call,
394 // or if the small one is not.
395 Register SmallReg = SmallSrc ? SrcReg : DstReg;
396 Register LargeReg = SmallSrc ? DstReg : SrcReg;
397 return any_of(Range&: LIS.getInterval(Reg: LargeReg), P: HasCall) ||
398 !any_of(Range&: LIS.getInterval(Reg: SmallReg), P: HasCall);
399}
400
401
402Register HexagonRegisterInfo::getFrameRegister(const MachineFunction
403 &MF) const {
404 const HexagonFrameLowering *TFI = getFrameLowering(MF);
405 if (TFI->hasFP(MF))
406 return getFrameRegister();
407 return getStackRegister();
408}
409
410
411Register HexagonRegisterInfo::getFrameRegister() const {
412 return Hexagon::R30;
413}
414
415
416Register HexagonRegisterInfo::getStackRegister() const {
417 return Hexagon::R29;
418}
419
420
421unsigned HexagonRegisterInfo::getHexagonSubRegIndex(
422 const TargetRegisterClass &RC, unsigned GenIdx) const {
423 assert(GenIdx == Hexagon::ps_sub_lo || GenIdx == Hexagon::ps_sub_hi);
424
425 static const unsigned ISub[] = { Hexagon::isub_lo, Hexagon::isub_hi };
426 static const unsigned VSub[] = { Hexagon::vsub_lo, Hexagon::vsub_hi };
427 static const unsigned WSub[] = { Hexagon::wsub_lo, Hexagon::wsub_hi };
428
429 switch (RC.getID()) {
430 case Hexagon::CtrRegs64RegClassID:
431 case Hexagon::DoubleRegsRegClassID:
432 return ISub[GenIdx];
433 case Hexagon::HvxWRRegClassID:
434 return VSub[GenIdx];
435 case Hexagon::HvxVQRRegClassID:
436 return WSub[GenIdx];
437 }
438
439 if (const TargetRegisterClass *SuperRC = *RC.getSuperClasses())
440 return getHexagonSubRegIndex(RC: *SuperRC, GenIdx);
441
442 llvm_unreachable("Invalid register class");
443}
444
445bool HexagonRegisterInfo::useFPForScavengingIndex(const MachineFunction &MF)
446 const {
447 return MF.getSubtarget<HexagonSubtarget>().getFrameLowering()->hasFP(MF);
448}
449
450const TargetRegisterClass *
451HexagonRegisterInfo::getPointerRegClass(const MachineFunction &MF,
452 unsigned Kind) const {
453 return &Hexagon::IntRegsRegClass;
454}
455

source code of llvm/lib/Target/Hexagon/HexagonRegisterInfo.cpp