1 //===- Thumb2InstrInfo.cpp - Thumb-2 Instruction 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 Thumb-2 implementation of the TargetInstrInfo class.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "Thumb2InstrInfo.h"
14 #include "ARMMachineFunctionInfo.h"
15 #include "ARMSubtarget.h"
16 #include "MCTargetDesc/ARMAddressingModes.h"
17 #include "llvm/CodeGen/MachineBasicBlock.h"
18 #include "llvm/CodeGen/MachineFrameInfo.h"
19 #include "llvm/CodeGen/MachineFunction.h"
20 #include "llvm/CodeGen/MachineInstr.h"
21 #include "llvm/CodeGen/MachineInstrBuilder.h"
22 #include "llvm/CodeGen/MachineMemOperand.h"
23 #include "llvm/CodeGen/MachineOperand.h"
24 #include "llvm/CodeGen/MachineRegisterInfo.h"
25 #include "llvm/CodeGen/TargetRegisterInfo.h"
26 #include "llvm/IR/DebugLoc.h"
27 #include "llvm/MC/MCInst.h"
28 #include "llvm/MC/MCInstBuilder.h"
29 #include "llvm/MC/MCInstrDesc.h"
30 #include "llvm/Support/CommandLine.h"
31 #include "llvm/Support/ErrorHandling.h"
32 #include "llvm/Support/MathExtras.h"
33 #include "llvm/Target/TargetMachine.h"
34 #include <cassert>
35
36 using namespace llvm;
37
38 static cl::opt<bool>
39 OldT2IfCvt("old-thumb2-ifcvt", cl::Hidden,
40 cl::desc("Use old-style Thumb2 if-conversion heuristics"),
41 cl::init(false));
42
43 static cl::opt<bool>
44 PreferNoCSEL("prefer-no-csel", cl::Hidden,
45 cl::desc("Prefer predicated Move to CSEL"),
46 cl::init(false));
47
Thumb2InstrInfo(const ARMSubtarget & STI)48 Thumb2InstrInfo::Thumb2InstrInfo(const ARMSubtarget &STI)
49 : ARMBaseInstrInfo(STI) {}
50
51 /// Return the noop instruction to use for a noop.
getNop() const52 MCInst Thumb2InstrInfo::getNop() const {
53 return MCInstBuilder(ARM::tHINT).addImm(0).addImm(ARMCC::AL).addReg(0);
54 }
55
getUnindexedOpcode(unsigned Opc) const56 unsigned Thumb2InstrInfo::getUnindexedOpcode(unsigned Opc) const {
57 // FIXME
58 return 0;
59 }
60
61 void
ReplaceTailWithBranchTo(MachineBasicBlock::iterator Tail,MachineBasicBlock * NewDest) const62 Thumb2InstrInfo::ReplaceTailWithBranchTo(MachineBasicBlock::iterator Tail,
63 MachineBasicBlock *NewDest) const {
64 MachineBasicBlock *MBB = Tail->getParent();
65 ARMFunctionInfo *AFI = MBB->getParent()->getInfo<ARMFunctionInfo>();
66 if (!AFI->hasITBlocks() || Tail->isBranch()) {
67 TargetInstrInfo::ReplaceTailWithBranchTo(Tail, NewDest);
68 return;
69 }
70
71 // If the first instruction of Tail is predicated, we may have to update
72 // the IT instruction.
73 Register PredReg;
74 ARMCC::CondCodes CC = getInstrPredicate(*Tail, PredReg);
75 MachineBasicBlock::iterator MBBI = Tail;
76 if (CC != ARMCC::AL)
77 // Expecting at least the t2IT instruction before it.
78 --MBBI;
79
80 // Actually replace the tail.
81 TargetInstrInfo::ReplaceTailWithBranchTo(Tail, NewDest);
82
83 // Fix up IT.
84 if (CC != ARMCC::AL) {
85 MachineBasicBlock::iterator E = MBB->begin();
86 unsigned Count = 4; // At most 4 instructions in an IT block.
87 while (Count && MBBI != E) {
88 if (MBBI->isDebugInstr()) {
89 --MBBI;
90 continue;
91 }
92 if (MBBI->getOpcode() == ARM::t2IT) {
93 unsigned Mask = MBBI->getOperand(1).getImm();
94 if (Count == 4)
95 MBBI->eraseFromParent();
96 else {
97 unsigned MaskOn = 1 << Count;
98 unsigned MaskOff = ~(MaskOn - 1);
99 MBBI->getOperand(1).setImm((Mask & MaskOff) | MaskOn);
100 }
101 return;
102 }
103 --MBBI;
104 --Count;
105 }
106
107 // Ctrl flow can reach here if branch folding is run before IT block
108 // formation pass.
109 }
110 }
111
112 bool
isLegalToSplitMBBAt(MachineBasicBlock & MBB,MachineBasicBlock::iterator MBBI) const113 Thumb2InstrInfo::isLegalToSplitMBBAt(MachineBasicBlock &MBB,
114 MachineBasicBlock::iterator MBBI) const {
115 while (MBBI->isDebugInstr()) {
116 ++MBBI;
117 if (MBBI == MBB.end())
118 return false;
119 }
120
121 Register PredReg;
122 return getITInstrPredicate(*MBBI, PredReg) == ARMCC::AL;
123 }
124
125 MachineInstr *
optimizeSelect(MachineInstr & MI,SmallPtrSetImpl<MachineInstr * > & SeenMIs,bool PreferFalse) const126 Thumb2InstrInfo::optimizeSelect(MachineInstr &MI,
127 SmallPtrSetImpl<MachineInstr *> &SeenMIs,
128 bool PreferFalse) const {
129 // Try to use the base optimizeSelect, which uses canFoldIntoMOVCC to fold the
130 // MOVCC into another instruction. If that fails on 8.1-M fall back to using a
131 // CSEL.
132 MachineInstr *RV = ARMBaseInstrInfo::optimizeSelect(MI, SeenMIs, PreferFalse);
133 if (!RV && getSubtarget().hasV8_1MMainlineOps() && !PreferNoCSEL) {
134 Register DestReg = MI.getOperand(0).getReg();
135
136 if (!DestReg.isVirtual())
137 return nullptr;
138
139 MachineInstrBuilder NewMI = BuildMI(*MI.getParent(), MI, MI.getDebugLoc(),
140 get(ARM::t2CSEL), DestReg)
141 .add(MI.getOperand(2))
142 .add(MI.getOperand(1))
143 .add(MI.getOperand(3));
144 SeenMIs.insert(NewMI);
145 return NewMI;
146 }
147 return RV;
148 }
149
copyPhysReg(MachineBasicBlock & MBB,MachineBasicBlock::iterator I,const DebugLoc & DL,MCRegister DestReg,MCRegister SrcReg,bool KillSrc) const150 void Thumb2InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
151 MachineBasicBlock::iterator I,
152 const DebugLoc &DL, MCRegister DestReg,
153 MCRegister SrcReg, bool KillSrc) const {
154 // Handle SPR, DPR, and QPR copies.
155 if (!ARM::GPRRegClass.contains(DestReg, SrcReg))
156 return ARMBaseInstrInfo::copyPhysReg(MBB, I, DL, DestReg, SrcReg, KillSrc);
157
158 BuildMI(MBB, I, DL, get(ARM::tMOVr), DestReg)
159 .addReg(SrcReg, getKillRegState(KillSrc))
160 .add(predOps(ARMCC::AL));
161 }
162
storeRegToStackSlot(MachineBasicBlock & MBB,MachineBasicBlock::iterator I,Register SrcReg,bool isKill,int FI,const TargetRegisterClass * RC,const TargetRegisterInfo * TRI,Register VReg) const163 void Thumb2InstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
164 MachineBasicBlock::iterator I,
165 Register SrcReg, bool isKill, int FI,
166 const TargetRegisterClass *RC,
167 const TargetRegisterInfo *TRI,
168 Register VReg) const {
169 DebugLoc DL;
170 if (I != MBB.end()) DL = I->getDebugLoc();
171
172 MachineFunction &MF = *MBB.getParent();
173 MachineFrameInfo &MFI = MF.getFrameInfo();
174 MachineMemOperand *MMO = MF.getMachineMemOperand(
175 MachinePointerInfo::getFixedStack(MF, FI), MachineMemOperand::MOStore,
176 MFI.getObjectSize(FI), MFI.getObjectAlign(FI));
177
178 if (ARM::GPRRegClass.hasSubClassEq(RC)) {
179 BuildMI(MBB, I, DL, get(ARM::t2STRi12))
180 .addReg(SrcReg, getKillRegState(isKill))
181 .addFrameIndex(FI)
182 .addImm(0)
183 .addMemOperand(MMO)
184 .add(predOps(ARMCC::AL));
185 return;
186 }
187
188 if (ARM::GPRPairRegClass.hasSubClassEq(RC)) {
189 // Thumb2 STRD expects its dest-registers to be in rGPR. Not a problem for
190 // gsub_0, but needs an extra constraint for gsub_1 (which could be sp
191 // otherwise).
192 if (SrcReg.isVirtual()) {
193 MachineRegisterInfo *MRI = &MF.getRegInfo();
194 MRI->constrainRegClass(SrcReg, &ARM::GPRPairnospRegClass);
195 }
196
197 MachineInstrBuilder MIB = BuildMI(MBB, I, DL, get(ARM::t2STRDi8));
198 AddDReg(MIB, SrcReg, ARM::gsub_0, getKillRegState(isKill), TRI);
199 AddDReg(MIB, SrcReg, ARM::gsub_1, 0, TRI);
200 MIB.addFrameIndex(FI).addImm(0).addMemOperand(MMO).add(predOps(ARMCC::AL));
201 return;
202 }
203
204 ARMBaseInstrInfo::storeRegToStackSlot(MBB, I, SrcReg, isKill, FI, RC, TRI,
205 Register());
206 }
207
loadRegFromStackSlot(MachineBasicBlock & MBB,MachineBasicBlock::iterator I,Register DestReg,int FI,const TargetRegisterClass * RC,const TargetRegisterInfo * TRI,Register VReg) const208 void Thumb2InstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
209 MachineBasicBlock::iterator I,
210 Register DestReg, int FI,
211 const TargetRegisterClass *RC,
212 const TargetRegisterInfo *TRI,
213 Register VReg) const {
214 MachineFunction &MF = *MBB.getParent();
215 MachineFrameInfo &MFI = MF.getFrameInfo();
216 MachineMemOperand *MMO = MF.getMachineMemOperand(
217 MachinePointerInfo::getFixedStack(MF, FI), MachineMemOperand::MOLoad,
218 MFI.getObjectSize(FI), MFI.getObjectAlign(FI));
219 DebugLoc DL;
220 if (I != MBB.end()) DL = I->getDebugLoc();
221
222 if (ARM::GPRRegClass.hasSubClassEq(RC)) {
223 BuildMI(MBB, I, DL, get(ARM::t2LDRi12), DestReg)
224 .addFrameIndex(FI)
225 .addImm(0)
226 .addMemOperand(MMO)
227 .add(predOps(ARMCC::AL));
228 return;
229 }
230
231 if (ARM::GPRPairRegClass.hasSubClassEq(RC)) {
232 // Thumb2 LDRD expects its dest-registers to be in rGPR. Not a problem for
233 // gsub_0, but needs an extra constraint for gsub_1 (which could be sp
234 // otherwise).
235 if (DestReg.isVirtual()) {
236 MachineRegisterInfo *MRI = &MF.getRegInfo();
237 MRI->constrainRegClass(DestReg, &ARM::GPRPairnospRegClass);
238 }
239
240 MachineInstrBuilder MIB = BuildMI(MBB, I, DL, get(ARM::t2LDRDi8));
241 AddDReg(MIB, DestReg, ARM::gsub_0, RegState::DefineNoRead, TRI);
242 AddDReg(MIB, DestReg, ARM::gsub_1, RegState::DefineNoRead, TRI);
243 MIB.addFrameIndex(FI).addImm(0).addMemOperand(MMO).add(predOps(ARMCC::AL));
244
245 if (DestReg.isPhysical())
246 MIB.addReg(DestReg, RegState::ImplicitDefine);
247 return;
248 }
249
250 ARMBaseInstrInfo::loadRegFromStackSlot(MBB, I, DestReg, FI, RC, TRI,
251 Register());
252 }
253
expandLoadStackGuard(MachineBasicBlock::iterator MI) const254 void Thumb2InstrInfo::expandLoadStackGuard(
255 MachineBasicBlock::iterator MI) const {
256 MachineFunction &MF = *MI->getParent()->getParent();
257 Module &M = *MF.getFunction().getParent();
258
259 if (M.getStackProtectorGuard() == "tls") {
260 expandLoadStackGuardBase(MI, ARM::t2MRC, ARM::t2LDRi12);
261 return;
262 }
263
264 const auto *GV = cast<GlobalValue>((*MI->memoperands_begin())->getValue());
265 if (MF.getSubtarget<ARMSubtarget>().isTargetELF() && !GV->isDSOLocal())
266 expandLoadStackGuardBase(MI, ARM::t2LDRLIT_ga_pcrel, ARM::t2LDRi12);
267 else if (MF.getTarget().isPositionIndependent())
268 expandLoadStackGuardBase(MI, ARM::t2MOV_ga_pcrel, ARM::t2LDRi12);
269 else
270 expandLoadStackGuardBase(MI, ARM::t2MOVi32imm, ARM::t2LDRi12);
271 }
272
commuteInstructionImpl(MachineInstr & MI,bool NewMI,unsigned OpIdx1,unsigned OpIdx2) const273 MachineInstr *Thumb2InstrInfo::commuteInstructionImpl(MachineInstr &MI,
274 bool NewMI,
275 unsigned OpIdx1,
276 unsigned OpIdx2) const {
277 switch (MI.getOpcode()) {
278 case ARM::MVE_VMAXNMAf16:
279 case ARM::MVE_VMAXNMAf32:
280 case ARM::MVE_VMINNMAf16:
281 case ARM::MVE_VMINNMAf32:
282 // Don't allow predicated instructions to be commuted.
283 if (getVPTInstrPredicate(MI) != ARMVCC::None)
284 return nullptr;
285 }
286 return ARMBaseInstrInfo::commuteInstructionImpl(MI, NewMI, OpIdx1, OpIdx2);
287 }
288
emitT2RegPlusImmediate(MachineBasicBlock & MBB,MachineBasicBlock::iterator & MBBI,const DebugLoc & dl,Register DestReg,Register BaseReg,int NumBytes,ARMCC::CondCodes Pred,Register PredReg,const ARMBaseInstrInfo & TII,unsigned MIFlags)289 void llvm::emitT2RegPlusImmediate(MachineBasicBlock &MBB,
290 MachineBasicBlock::iterator &MBBI,
291 const DebugLoc &dl, Register DestReg,
292 Register BaseReg, int NumBytes,
293 ARMCC::CondCodes Pred, Register PredReg,
294 const ARMBaseInstrInfo &TII,
295 unsigned MIFlags) {
296 if (NumBytes == 0 && DestReg != BaseReg) {
297 BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), DestReg)
298 .addReg(BaseReg, RegState::Kill)
299 .addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
300 return;
301 }
302
303 bool isSub = NumBytes < 0;
304 if (isSub) NumBytes = -NumBytes;
305
306 // If profitable, use a movw or movt to materialize the offset.
307 // FIXME: Use the scavenger to grab a scratch register.
308 if (DestReg != ARM::SP && DestReg != BaseReg &&
309 NumBytes >= 4096 &&
310 ARM_AM::getT2SOImmVal(NumBytes) == -1) {
311 bool Fits = false;
312 if (NumBytes < 65536) {
313 // Use a movw to materialize the 16-bit constant.
314 BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVi16), DestReg)
315 .addImm(NumBytes)
316 .addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
317 Fits = true;
318 } else if ((NumBytes & 0xffff) == 0) {
319 // Use a movt to materialize the 32-bit constant.
320 BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVTi16), DestReg)
321 .addReg(DestReg)
322 .addImm(NumBytes >> 16)
323 .addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
324 Fits = true;
325 }
326
327 if (Fits) {
328 if (isSub) {
329 BuildMI(MBB, MBBI, dl, TII.get(ARM::t2SUBrr), DestReg)
330 .addReg(BaseReg)
331 .addReg(DestReg, RegState::Kill)
332 .add(predOps(Pred, PredReg))
333 .add(condCodeOp())
334 .setMIFlags(MIFlags);
335 } else {
336 // Here we know that DestReg is not SP but we do not
337 // know anything about BaseReg. t2ADDrr is an invalid
338 // instruction is SP is used as the second argument, but
339 // is fine if SP is the first argument. To be sure we
340 // do not generate invalid encoding, put BaseReg first.
341 BuildMI(MBB, MBBI, dl, TII.get(ARM::t2ADDrr), DestReg)
342 .addReg(BaseReg)
343 .addReg(DestReg, RegState::Kill)
344 .add(predOps(Pred, PredReg))
345 .add(condCodeOp())
346 .setMIFlags(MIFlags);
347 }
348 return;
349 }
350 }
351
352 while (NumBytes) {
353 unsigned ThisVal = NumBytes;
354 unsigned Opc = 0;
355 if (DestReg == ARM::SP && BaseReg != ARM::SP) {
356 // mov sp, rn. Note t2MOVr cannot be used.
357 BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), DestReg)
358 .addReg(BaseReg)
359 .setMIFlags(MIFlags)
360 .add(predOps(ARMCC::AL));
361 BaseReg = ARM::SP;
362 continue;
363 }
364
365 assert((DestReg != ARM::SP || BaseReg == ARM::SP) &&
366 "Writing to SP, from other register.");
367
368 // Try to use T1, as it smaller
369 if ((DestReg == ARM::SP) && (ThisVal < ((1 << 7) - 1) * 4)) {
370 assert((ThisVal & 3) == 0 && "Stack update is not multiple of 4?");
371 Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
372 BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
373 .addReg(BaseReg)
374 .addImm(ThisVal / 4)
375 .setMIFlags(MIFlags)
376 .add(predOps(ARMCC::AL));
377 break;
378 }
379 bool HasCCOut = true;
380 int ImmIsT2SO = ARM_AM::getT2SOImmVal(ThisVal);
381 bool ToSP = DestReg == ARM::SP;
382 unsigned t2SUB = ToSP ? ARM::t2SUBspImm : ARM::t2SUBri;
383 unsigned t2ADD = ToSP ? ARM::t2ADDspImm : ARM::t2ADDri;
384 unsigned t2SUBi12 = ToSP ? ARM::t2SUBspImm12 : ARM::t2SUBri12;
385 unsigned t2ADDi12 = ToSP ? ARM::t2ADDspImm12 : ARM::t2ADDri12;
386 Opc = isSub ? t2SUB : t2ADD;
387 // Prefer T2: sub rd, rn, so_imm | sub sp, sp, so_imm
388 if (ImmIsT2SO != -1) {
389 NumBytes = 0;
390 } else if (ThisVal < 4096) {
391 // Prefer T3 if can make it in a single go: subw rd, rn, imm12 | subw sp,
392 // sp, imm12
393 Opc = isSub ? t2SUBi12 : t2ADDi12;
394 HasCCOut = false;
395 NumBytes = 0;
396 } else {
397 // Use one T2 instruction to reduce NumBytes
398 // FIXME: Move this to ARMAddressingModes.h?
399 unsigned RotAmt = llvm::countl_zero(ThisVal);
400 ThisVal = ThisVal & llvm::rotr<uint32_t>(0xff000000U, RotAmt);
401 NumBytes &= ~ThisVal;
402 assert(ARM_AM::getT2SOImmVal(ThisVal) != -1 &&
403 "Bit extraction didn't work?");
404 }
405
406 // Build the new ADD / SUB.
407 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
408 .addReg(BaseReg, RegState::Kill)
409 .addImm(ThisVal)
410 .add(predOps(ARMCC::AL))
411 .setMIFlags(MIFlags);
412 if (HasCCOut)
413 MIB.add(condCodeOp());
414
415 BaseReg = DestReg;
416 }
417 }
418
419 static unsigned
negativeOffsetOpcode(unsigned opcode)420 negativeOffsetOpcode(unsigned opcode)
421 {
422 switch (opcode) {
423 case ARM::t2LDRi12: return ARM::t2LDRi8;
424 case ARM::t2LDRHi12: return ARM::t2LDRHi8;
425 case ARM::t2LDRBi12: return ARM::t2LDRBi8;
426 case ARM::t2LDRSHi12: return ARM::t2LDRSHi8;
427 case ARM::t2LDRSBi12: return ARM::t2LDRSBi8;
428 case ARM::t2STRi12: return ARM::t2STRi8;
429 case ARM::t2STRBi12: return ARM::t2STRBi8;
430 case ARM::t2STRHi12: return ARM::t2STRHi8;
431 case ARM::t2PLDi12: return ARM::t2PLDi8;
432 case ARM::t2PLDWi12: return ARM::t2PLDWi8;
433 case ARM::t2PLIi12: return ARM::t2PLIi8;
434
435 case ARM::t2LDRi8:
436 case ARM::t2LDRHi8:
437 case ARM::t2LDRBi8:
438 case ARM::t2LDRSHi8:
439 case ARM::t2LDRSBi8:
440 case ARM::t2STRi8:
441 case ARM::t2STRBi8:
442 case ARM::t2STRHi8:
443 case ARM::t2PLDi8:
444 case ARM::t2PLDWi8:
445 case ARM::t2PLIi8:
446 return opcode;
447
448 default:
449 llvm_unreachable("unknown thumb2 opcode.");
450 }
451 }
452
453 static unsigned
positiveOffsetOpcode(unsigned opcode)454 positiveOffsetOpcode(unsigned opcode)
455 {
456 switch (opcode) {
457 case ARM::t2LDRi8: return ARM::t2LDRi12;
458 case ARM::t2LDRHi8: return ARM::t2LDRHi12;
459 case ARM::t2LDRBi8: return ARM::t2LDRBi12;
460 case ARM::t2LDRSHi8: return ARM::t2LDRSHi12;
461 case ARM::t2LDRSBi8: return ARM::t2LDRSBi12;
462 case ARM::t2STRi8: return ARM::t2STRi12;
463 case ARM::t2STRBi8: return ARM::t2STRBi12;
464 case ARM::t2STRHi8: return ARM::t2STRHi12;
465 case ARM::t2PLDi8: return ARM::t2PLDi12;
466 case ARM::t2PLDWi8: return ARM::t2PLDWi12;
467 case ARM::t2PLIi8: return ARM::t2PLIi12;
468
469 case ARM::t2LDRi12:
470 case ARM::t2LDRHi12:
471 case ARM::t2LDRBi12:
472 case ARM::t2LDRSHi12:
473 case ARM::t2LDRSBi12:
474 case ARM::t2STRi12:
475 case ARM::t2STRBi12:
476 case ARM::t2STRHi12:
477 case ARM::t2PLDi12:
478 case ARM::t2PLDWi12:
479 case ARM::t2PLIi12:
480 return opcode;
481
482 default:
483 llvm_unreachable("unknown thumb2 opcode.");
484 }
485 }
486
487 static unsigned
immediateOffsetOpcode(unsigned opcode)488 immediateOffsetOpcode(unsigned opcode)
489 {
490 switch (opcode) {
491 case ARM::t2LDRs: return ARM::t2LDRi12;
492 case ARM::t2LDRHs: return ARM::t2LDRHi12;
493 case ARM::t2LDRBs: return ARM::t2LDRBi12;
494 case ARM::t2LDRSHs: return ARM::t2LDRSHi12;
495 case ARM::t2LDRSBs: return ARM::t2LDRSBi12;
496 case ARM::t2STRs: return ARM::t2STRi12;
497 case ARM::t2STRBs: return ARM::t2STRBi12;
498 case ARM::t2STRHs: return ARM::t2STRHi12;
499 case ARM::t2PLDs: return ARM::t2PLDi12;
500 case ARM::t2PLDWs: return ARM::t2PLDWi12;
501 case ARM::t2PLIs: return ARM::t2PLIi12;
502
503 case ARM::t2LDRi12:
504 case ARM::t2LDRHi12:
505 case ARM::t2LDRBi12:
506 case ARM::t2LDRSHi12:
507 case ARM::t2LDRSBi12:
508 case ARM::t2STRi12:
509 case ARM::t2STRBi12:
510 case ARM::t2STRHi12:
511 case ARM::t2PLDi12:
512 case ARM::t2PLDWi12:
513 case ARM::t2PLIi12:
514 case ARM::t2LDRi8:
515 case ARM::t2LDRHi8:
516 case ARM::t2LDRBi8:
517 case ARM::t2LDRSHi8:
518 case ARM::t2LDRSBi8:
519 case ARM::t2STRi8:
520 case ARM::t2STRBi8:
521 case ARM::t2STRHi8:
522 case ARM::t2PLDi8:
523 case ARM::t2PLDWi8:
524 case ARM::t2PLIi8:
525 return opcode;
526
527 default:
528 llvm_unreachable("unknown thumb2 opcode.");
529 }
530 }
531
rewriteT2FrameIndex(MachineInstr & MI,unsigned FrameRegIdx,Register FrameReg,int & Offset,const ARMBaseInstrInfo & TII,const TargetRegisterInfo * TRI)532 bool llvm::rewriteT2FrameIndex(MachineInstr &MI, unsigned FrameRegIdx,
533 Register FrameReg, int &Offset,
534 const ARMBaseInstrInfo &TII,
535 const TargetRegisterInfo *TRI) {
536 unsigned Opcode = MI.getOpcode();
537 const MCInstrDesc &Desc = MI.getDesc();
538 unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
539 bool isSub = false;
540
541 MachineFunction &MF = *MI.getParent()->getParent();
542 const TargetRegisterClass *RegClass =
543 TII.getRegClass(Desc, FrameRegIdx, TRI, MF);
544
545 // Memory operands in inline assembly always use AddrModeT2_i12.
546 if (Opcode == ARM::INLINEASM || Opcode == ARM::INLINEASM_BR)
547 AddrMode = ARMII::AddrModeT2_i12; // FIXME. mode for thumb2?
548
549 const bool IsSP = Opcode == ARM::t2ADDspImm12 || Opcode == ARM::t2ADDspImm;
550 if (IsSP || Opcode == ARM::t2ADDri || Opcode == ARM::t2ADDri12) {
551 Offset += MI.getOperand(FrameRegIdx+1).getImm();
552
553 Register PredReg;
554 if (Offset == 0 && getInstrPredicate(MI, PredReg) == ARMCC::AL &&
555 !MI.definesRegister(ARM::CPSR)) {
556 // Turn it into a move.
557 MI.setDesc(TII.get(ARM::tMOVr));
558 MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
559 // Remove offset and remaining explicit predicate operands.
560 do MI.removeOperand(FrameRegIdx+1);
561 while (MI.getNumOperands() > FrameRegIdx+1);
562 MachineInstrBuilder MIB(*MI.getParent()->getParent(), &MI);
563 MIB.add(predOps(ARMCC::AL));
564 return true;
565 }
566
567 bool HasCCOut = (Opcode != ARM::t2ADDspImm12 && Opcode != ARM::t2ADDri12);
568
569 if (Offset < 0) {
570 Offset = -Offset;
571 isSub = true;
572 MI.setDesc(IsSP ? TII.get(ARM::t2SUBspImm) : TII.get(ARM::t2SUBri));
573 } else {
574 MI.setDesc(IsSP ? TII.get(ARM::t2ADDspImm) : TII.get(ARM::t2ADDri));
575 }
576
577 // Common case: small offset, fits into instruction.
578 if (ARM_AM::getT2SOImmVal(Offset) != -1) {
579 MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
580 MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset);
581 // Add cc_out operand if the original instruction did not have one.
582 if (!HasCCOut)
583 MI.addOperand(MachineOperand::CreateReg(0, false));
584 Offset = 0;
585 return true;
586 }
587 // Another common case: imm12.
588 if (Offset < 4096 &&
589 (!HasCCOut || MI.getOperand(MI.getNumOperands()-1).getReg() == 0)) {
590 unsigned NewOpc = isSub ? IsSP ? ARM::t2SUBspImm12 : ARM::t2SUBri12
591 : IsSP ? ARM::t2ADDspImm12 : ARM::t2ADDri12;
592 MI.setDesc(TII.get(NewOpc));
593 MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
594 MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset);
595 // Remove the cc_out operand.
596 if (HasCCOut)
597 MI.removeOperand(MI.getNumOperands()-1);
598 Offset = 0;
599 return true;
600 }
601
602 // Otherwise, extract 8 adjacent bits from the immediate into this
603 // t2ADDri/t2SUBri.
604 unsigned RotAmt = llvm::countl_zero<unsigned>(Offset);
605 unsigned ThisImmVal = Offset & llvm::rotr<uint32_t>(0xff000000U, RotAmt);
606
607 // We will handle these bits from offset, clear them.
608 Offset &= ~ThisImmVal;
609
610 assert(ARM_AM::getT2SOImmVal(ThisImmVal) != -1 &&
611 "Bit extraction didn't work?");
612 MI.getOperand(FrameRegIdx+1).ChangeToImmediate(ThisImmVal);
613 // Add cc_out operand if the original instruction did not have one.
614 if (!HasCCOut)
615 MI.addOperand(MachineOperand::CreateReg(0, false));
616 } else {
617 // AddrMode4 and AddrMode6 cannot handle any offset.
618 if (AddrMode == ARMII::AddrMode4 || AddrMode == ARMII::AddrMode6)
619 return false;
620
621 // AddrModeT2_so cannot handle any offset. If there is no offset
622 // register then we change to an immediate version.
623 unsigned NewOpc = Opcode;
624 if (AddrMode == ARMII::AddrModeT2_so) {
625 Register OffsetReg = MI.getOperand(FrameRegIdx + 1).getReg();
626 if (OffsetReg != 0) {
627 MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
628 return Offset == 0;
629 }
630
631 MI.removeOperand(FrameRegIdx+1);
632 MI.getOperand(FrameRegIdx+1).ChangeToImmediate(0);
633 NewOpc = immediateOffsetOpcode(Opcode);
634 AddrMode = ARMII::AddrModeT2_i12;
635 }
636
637 unsigned NumBits = 0;
638 unsigned Scale = 1;
639 if (AddrMode == ARMII::AddrModeT2_i8neg ||
640 AddrMode == ARMII::AddrModeT2_i12) {
641 // i8 supports only negative, and i12 supports only positive, so
642 // based on Offset sign convert Opcode to the appropriate
643 // instruction
644 Offset += MI.getOperand(FrameRegIdx+1).getImm();
645 if (Offset < 0) {
646 NewOpc = negativeOffsetOpcode(Opcode);
647 NumBits = 8;
648 isSub = true;
649 Offset = -Offset;
650 } else {
651 NewOpc = positiveOffsetOpcode(Opcode);
652 NumBits = 12;
653 }
654 } else if (AddrMode == ARMII::AddrMode5) {
655 // VFP address mode.
656 const MachineOperand &OffOp = MI.getOperand(FrameRegIdx+1);
657 int InstrOffs = ARM_AM::getAM5Offset(OffOp.getImm());
658 if (ARM_AM::getAM5Op(OffOp.getImm()) == ARM_AM::sub)
659 InstrOffs *= -1;
660 NumBits = 8;
661 Scale = 4;
662 Offset += InstrOffs * 4;
663 assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!");
664 if (Offset < 0) {
665 Offset = -Offset;
666 isSub = true;
667 }
668 } else if (AddrMode == ARMII::AddrMode5FP16) {
669 // VFP address mode.
670 const MachineOperand &OffOp = MI.getOperand(FrameRegIdx+1);
671 int InstrOffs = ARM_AM::getAM5FP16Offset(OffOp.getImm());
672 if (ARM_AM::getAM5FP16Op(OffOp.getImm()) == ARM_AM::sub)
673 InstrOffs *= -1;
674 NumBits = 8;
675 Scale = 2;
676 Offset += InstrOffs * 2;
677 assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!");
678 if (Offset < 0) {
679 Offset = -Offset;
680 isSub = true;
681 }
682 } else if (AddrMode == ARMII::AddrModeT2_i7s4 ||
683 AddrMode == ARMII::AddrModeT2_i7s2 ||
684 AddrMode == ARMII::AddrModeT2_i7) {
685 Offset += MI.getOperand(FrameRegIdx + 1).getImm();
686 unsigned OffsetMask;
687 switch (AddrMode) {
688 case ARMII::AddrModeT2_i7s4: NumBits = 9; OffsetMask = 0x3; break;
689 case ARMII::AddrModeT2_i7s2: NumBits = 8; OffsetMask = 0x1; break;
690 default: NumBits = 7; OffsetMask = 0x0; break;
691 }
692 // MCInst operand expects already scaled value.
693 Scale = 1;
694 assert((Offset & OffsetMask) == 0 && "Can't encode this offset!");
695 (void)OffsetMask; // squash unused-variable warning at -NDEBUG
696 } else if (AddrMode == ARMII::AddrModeT2_i8s4) {
697 Offset += MI.getOperand(FrameRegIdx + 1).getImm();
698 NumBits = 8 + 2;
699 // MCInst operand expects already scaled value.
700 Scale = 1;
701 assert((Offset & 3) == 0 && "Can't encode this offset!");
702 } else if (AddrMode == ARMII::AddrModeT2_ldrex) {
703 Offset += MI.getOperand(FrameRegIdx + 1).getImm() * 4;
704 NumBits = 8; // 8 bits scaled by 4
705 Scale = 4;
706 assert((Offset & 3) == 0 && "Can't encode this offset!");
707 } else {
708 llvm_unreachable("Unsupported addressing mode!");
709 }
710
711 if (NewOpc != Opcode)
712 MI.setDesc(TII.get(NewOpc));
713
714 MachineOperand &ImmOp = MI.getOperand(FrameRegIdx+1);
715
716 // Attempt to fold address computation
717 // Common case: small offset, fits into instruction. We need to make sure
718 // the register class is correct too, for instructions like the MVE
719 // VLDRH.32, which only accepts low tGPR registers.
720 int ImmedOffset = Offset / Scale;
721 unsigned Mask = (1 << NumBits) - 1;
722 if ((unsigned)Offset <= Mask * Scale &&
723 (FrameReg.isVirtual() || RegClass->contains(FrameReg))) {
724 if (FrameReg.isVirtual()) {
725 // Make sure the register class for the virtual register is correct
726 MachineRegisterInfo *MRI = &MF.getRegInfo();
727 if (!MRI->constrainRegClass(FrameReg, RegClass))
728 llvm_unreachable("Unable to constrain virtual register class.");
729 }
730
731 // Replace the FrameIndex with fp/sp
732 MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
733 if (isSub) {
734 if (AddrMode == ARMII::AddrMode5 || AddrMode == ARMII::AddrMode5FP16)
735 // FIXME: Not consistent.
736 ImmedOffset |= 1 << NumBits;
737 else
738 ImmedOffset = -ImmedOffset;
739 }
740 ImmOp.ChangeToImmediate(ImmedOffset);
741 Offset = 0;
742 return true;
743 }
744
745 // Otherwise, offset doesn't fit. Pull in what we can to simplify
746 ImmedOffset = ImmedOffset & Mask;
747 if (isSub) {
748 if (AddrMode == ARMII::AddrMode5 || AddrMode == ARMII::AddrMode5FP16)
749 // FIXME: Not consistent.
750 ImmedOffset |= 1 << NumBits;
751 else {
752 ImmedOffset = -ImmedOffset;
753 if (ImmedOffset == 0)
754 // Change the opcode back if the encoded offset is zero.
755 MI.setDesc(TII.get(positiveOffsetOpcode(NewOpc)));
756 }
757 }
758 ImmOp.ChangeToImmediate(ImmedOffset);
759 Offset &= ~(Mask*Scale);
760 }
761
762 Offset = (isSub) ? -Offset : Offset;
763 return Offset == 0 && (FrameReg.isVirtual() || RegClass->contains(FrameReg));
764 }
765
getITInstrPredicate(const MachineInstr & MI,Register & PredReg)766 ARMCC::CondCodes llvm::getITInstrPredicate(const MachineInstr &MI,
767 Register &PredReg) {
768 unsigned Opc = MI.getOpcode();
769 if (Opc == ARM::tBcc || Opc == ARM::t2Bcc)
770 return ARMCC::AL;
771 return getInstrPredicate(MI, PredReg);
772 }
773
findFirstVPTPredOperandIdx(const MachineInstr & MI)774 int llvm::findFirstVPTPredOperandIdx(const MachineInstr &MI) {
775 const MCInstrDesc &MCID = MI.getDesc();
776
777 for (unsigned i = 0, e = MCID.getNumOperands(); i != e; ++i)
778 if (ARM::isVpred(MCID.operands()[i].OperandType))
779 return i;
780
781 return -1;
782 }
783
getVPTInstrPredicate(const MachineInstr & MI,Register & PredReg)784 ARMVCC::VPTCodes llvm::getVPTInstrPredicate(const MachineInstr &MI,
785 Register &PredReg) {
786 int PIdx = findFirstVPTPredOperandIdx(MI);
787 if (PIdx == -1) {
788 PredReg = 0;
789 return ARMVCC::None;
790 }
791
792 PredReg = MI.getOperand(PIdx+1).getReg();
793 return (ARMVCC::VPTCodes)MI.getOperand(PIdx).getImm();
794 }
795
recomputeVPTBlockMask(MachineInstr & Instr)796 void llvm::recomputeVPTBlockMask(MachineInstr &Instr) {
797 assert(isVPTOpcode(Instr.getOpcode()) && "Not a VPST or VPT Instruction!");
798
799 MachineOperand &MaskOp = Instr.getOperand(0);
800 assert(MaskOp.isImm() && "Operand 0 is not the block mask of the VPT/VPST?!");
801
802 MachineBasicBlock::iterator Iter = ++Instr.getIterator(),
803 End = Instr.getParent()->end();
804
805 while (Iter != End && Iter->isDebugInstr())
806 ++Iter;
807
808 // Verify that the instruction after the VPT/VPST is predicated (it should
809 // be), and skip it.
810 assert(Iter != End && "Expected some instructions in any VPT block");
811 assert(
812 getVPTInstrPredicate(*Iter) == ARMVCC::Then &&
813 "VPT/VPST should be followed by an instruction with a 'then' predicate!");
814 ++Iter;
815
816 // Iterate over the predicated instructions, updating the BlockMask as we go.
817 ARM::PredBlockMask BlockMask = ARM::PredBlockMask::T;
818 while (Iter != End) {
819 if (Iter->isDebugInstr()) {
820 ++Iter;
821 continue;
822 }
823 ARMVCC::VPTCodes Pred = getVPTInstrPredicate(*Iter);
824 if (Pred == ARMVCC::None)
825 break;
826 BlockMask = expandPredBlockMask(BlockMask, Pred);
827 ++Iter;
828 }
829
830 // Rewrite the BlockMask.
831 MaskOp.setImm((int64_t)(BlockMask));
832 }
833