LLVM  9.0.0svn
AArch64LoadStoreOptimizer.cpp
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1 //===- AArch64LoadStoreOptimizer.cpp - AArch64 load/store opt. pass -------===//
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 a pass that performs load / store related peephole
10 // optimizations. This pass should be run after register allocation.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "AArch64InstrInfo.h"
15 #include "AArch64Subtarget.h"
17 #include "llvm/ADT/BitVector.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/Statistic.h"
20 #include "llvm/ADT/StringRef.h"
30 #include "llvm/IR/DebugLoc.h"
31 #include "llvm/MC/MCRegisterInfo.h"
32 #include "llvm/Pass.h"
34 #include "llvm/Support/Debug.h"
37 #include <cassert>
38 #include <cstdint>
39 #include <iterator>
40 #include <limits>
41 
42 using namespace llvm;
43 
44 #define DEBUG_TYPE "aarch64-ldst-opt"
45 
46 STATISTIC(NumPairCreated, "Number of load/store pair instructions generated");
47 STATISTIC(NumPostFolded, "Number of post-index updates folded");
48 STATISTIC(NumPreFolded, "Number of pre-index updates folded");
49 STATISTIC(NumUnscaledPairCreated,
50  "Number of load/store from unscaled generated");
51 STATISTIC(NumZeroStoresPromoted, "Number of narrow zero stores promoted");
52 STATISTIC(NumLoadsFromStoresPromoted, "Number of loads from stores promoted");
53 
54 // The LdStLimit limits how far we search for load/store pairs.
55 static cl::opt<unsigned> LdStLimit("aarch64-load-store-scan-limit",
56  cl::init(20), cl::Hidden);
57 
58 // The UpdateLimit limits how far we search for update instructions when we form
59 // pre-/post-index instructions.
60 static cl::opt<unsigned> UpdateLimit("aarch64-update-scan-limit", cl::init(100),
61  cl::Hidden);
62 
63 #define AARCH64_LOAD_STORE_OPT_NAME "AArch64 load / store optimization pass"
64 
65 namespace {
66 
67 using LdStPairFlags = struct LdStPairFlags {
68  // If a matching instruction is found, MergeForward is set to true if the
69  // merge is to remove the first instruction and replace the second with
70  // a pair-wise insn, and false if the reverse is true.
71  bool MergeForward = false;
72 
73  // SExtIdx gives the index of the result of the load pair that must be
74  // extended. The value of SExtIdx assumes that the paired load produces the
75  // value in this order: (I, returned iterator), i.e., -1 means no value has
76  // to be extended, 0 means I, and 1 means the returned iterator.
77  int SExtIdx = -1;
78 
79  LdStPairFlags() = default;
80 
81  void setMergeForward(bool V = true) { MergeForward = V; }
82  bool getMergeForward() const { return MergeForward; }
83 
84  void setSExtIdx(int V) { SExtIdx = V; }
85  int getSExtIdx() const { return SExtIdx; }
86 };
87 
88 struct AArch64LoadStoreOpt : public MachineFunctionPass {
89  static char ID;
90 
91  AArch64LoadStoreOpt() : MachineFunctionPass(ID) {
93  }
94 
95  AliasAnalysis *AA;
96  const AArch64InstrInfo *TII;
97  const TargetRegisterInfo *TRI;
98  const AArch64Subtarget *Subtarget;
99 
100  // Track which register units have been modified and used.
101  LiveRegUnits ModifiedRegUnits, UsedRegUnits;
102 
103  void getAnalysisUsage(AnalysisUsage &AU) const override {
106  }
107 
108  // Scan the instructions looking for a load/store that can be combined
109  // with the current instruction into a load/store pair.
110  // Return the matching instruction if one is found, else MBB->end().
112  LdStPairFlags &Flags,
113  unsigned Limit,
114  bool FindNarrowMerge);
115 
116  // Scan the instructions looking for a store that writes to the address from
117  // which the current load instruction reads. Return true if one is found.
118  bool findMatchingStore(MachineBasicBlock::iterator I, unsigned Limit,
120 
121  // Merge the two instructions indicated into a wider narrow store instruction.
123  mergeNarrowZeroStores(MachineBasicBlock::iterator I,
125  const LdStPairFlags &Flags);
126 
127  // Merge the two instructions indicated into a single pair-wise instruction.
129  mergePairedInsns(MachineBasicBlock::iterator I,
131  const LdStPairFlags &Flags);
132 
133  // Promote the load that reads directly from the address stored to.
135  promoteLoadFromStore(MachineBasicBlock::iterator LoadI,
137 
138  // Scan the instruction list to find a base register update that can
139  // be combined with the current instruction (a load or store) using
140  // pre or post indexed addressing with writeback. Scan forwards.
142  findMatchingUpdateInsnForward(MachineBasicBlock::iterator I,
143  int UnscaledOffset, unsigned Limit);
144 
145  // Scan the instruction list to find a base register update that can
146  // be combined with the current instruction (a load or store) using
147  // pre or post indexed addressing with writeback. Scan backwards.
149  findMatchingUpdateInsnBackward(MachineBasicBlock::iterator I, unsigned Limit);
150 
151  // Find an instruction that updates the base register of the ld/st
152  // instruction.
153  bool isMatchingUpdateInsn(MachineInstr &MemMI, MachineInstr &MI,
154  unsigned BaseReg, int Offset);
155 
156  // Merge a pre- or post-index base register update into a ld/st instruction.
158  mergeUpdateInsn(MachineBasicBlock::iterator I,
159  MachineBasicBlock::iterator Update, bool IsPreIdx);
160 
161  // Find and merge zero store instructions.
162  bool tryToMergeZeroStInst(MachineBasicBlock::iterator &MBBI);
163 
164  // Find and pair ldr/str instructions.
165  bool tryToPairLdStInst(MachineBasicBlock::iterator &MBBI);
166 
167  // Find and promote load instructions which read directly from store.
168  bool tryToPromoteLoadFromStore(MachineBasicBlock::iterator &MBBI);
169 
170  // Find and merge a base register updates before or after a ld/st instruction.
171  bool tryToMergeLdStUpdate(MachineBasicBlock::iterator &MBBI);
172 
173  bool optimizeBlock(MachineBasicBlock &MBB, bool EnableNarrowZeroStOpt);
174 
175  bool runOnMachineFunction(MachineFunction &Fn) override;
176 
177  MachineFunctionProperties getRequiredProperties() const override {
180  }
181 
182  StringRef getPassName() const override { return AARCH64_LOAD_STORE_OPT_NAME; }
183 };
184 
185 char AArch64LoadStoreOpt::ID = 0;
186 
187 } // end anonymous namespace
188 
189 INITIALIZE_PASS(AArch64LoadStoreOpt, "aarch64-ldst-opt",
190  AARCH64_LOAD_STORE_OPT_NAME, false, false)
191 
192 static bool isNarrowStore(unsigned Opc) {
193  switch (Opc) {
194  default:
195  return false;
196  case AArch64::STRBBui:
197  case AArch64::STURBBi:
198  case AArch64::STRHHui:
199  case AArch64::STURHHi:
200  return true;
201  }
202 }
203 
204 // Scaling factor for unscaled load or store.
206  switch (MI.getOpcode()) {
207  default:
208  llvm_unreachable("Opcode has unknown scale!");
209  case AArch64::LDRBBui:
210  case AArch64::LDURBBi:
211  case AArch64::LDRSBWui:
212  case AArch64::LDURSBWi:
213  case AArch64::STRBBui:
214  case AArch64::STURBBi:
215  return 1;
216  case AArch64::LDRHHui:
217  case AArch64::LDURHHi:
218  case AArch64::LDRSHWui:
219  case AArch64::LDURSHWi:
220  case AArch64::STRHHui:
221  case AArch64::STURHHi:
222  return 2;
223  case AArch64::LDRSui:
224  case AArch64::LDURSi:
225  case AArch64::LDRSWui:
226  case AArch64::LDURSWi:
227  case AArch64::LDRWui:
228  case AArch64::LDURWi:
229  case AArch64::STRSui:
230  case AArch64::STURSi:
231  case AArch64::STRWui:
232  case AArch64::STURWi:
233  case AArch64::LDPSi:
234  case AArch64::LDPSWi:
235  case AArch64::LDPWi:
236  case AArch64::STPSi:
237  case AArch64::STPWi:
238  return 4;
239  case AArch64::LDRDui:
240  case AArch64::LDURDi:
241  case AArch64::LDRXui:
242  case AArch64::LDURXi:
243  case AArch64::STRDui:
244  case AArch64::STURDi:
245  case AArch64::STRXui:
246  case AArch64::STURXi:
247  case AArch64::LDPDi:
248  case AArch64::LDPXi:
249  case AArch64::STPDi:
250  case AArch64::STPXi:
251  return 8;
252  case AArch64::LDRQui:
253  case AArch64::LDURQi:
254  case AArch64::STRQui:
255  case AArch64::STURQi:
256  case AArch64::LDPQi:
257  case AArch64::STPQi:
258  return 16;
259  }
260 }
261 
262 static unsigned getMatchingNonSExtOpcode(unsigned Opc,
263  bool *IsValidLdStrOpc = nullptr) {
264  if (IsValidLdStrOpc)
265  *IsValidLdStrOpc = true;
266  switch (Opc) {
267  default:
268  if (IsValidLdStrOpc)
269  *IsValidLdStrOpc = false;
271  case AArch64::STRDui:
272  case AArch64::STURDi:
273  case AArch64::STRQui:
274  case AArch64::STURQi:
275  case AArch64::STRBBui:
276  case AArch64::STURBBi:
277  case AArch64::STRHHui:
278  case AArch64::STURHHi:
279  case AArch64::STRWui:
280  case AArch64::STURWi:
281  case AArch64::STRXui:
282  case AArch64::STURXi:
283  case AArch64::LDRDui:
284  case AArch64::LDURDi:
285  case AArch64::LDRQui:
286  case AArch64::LDURQi:
287  case AArch64::LDRWui:
288  case AArch64::LDURWi:
289  case AArch64::LDRXui:
290  case AArch64::LDURXi:
291  case AArch64::STRSui:
292  case AArch64::STURSi:
293  case AArch64::LDRSui:
294  case AArch64::LDURSi:
295  return Opc;
296  case AArch64::LDRSWui:
297  return AArch64::LDRWui;
298  case AArch64::LDURSWi:
299  return AArch64::LDURWi;
300  }
301 }
302 
303 static unsigned getMatchingWideOpcode(unsigned Opc) {
304  switch (Opc) {
305  default:
306  llvm_unreachable("Opcode has no wide equivalent!");
307  case AArch64::STRBBui:
308  return AArch64::STRHHui;
309  case AArch64::STRHHui:
310  return AArch64::STRWui;
311  case AArch64::STURBBi:
312  return AArch64::STURHHi;
313  case AArch64::STURHHi:
314  return AArch64::STURWi;
315  case AArch64::STURWi:
316  return AArch64::STURXi;
317  case AArch64::STRWui:
318  return AArch64::STRXui;
319  }
320 }
321 
322 static unsigned getMatchingPairOpcode(unsigned Opc) {
323  switch (Opc) {
324  default:
325  llvm_unreachable("Opcode has no pairwise equivalent!");
326  case AArch64::STRSui:
327  case AArch64::STURSi:
328  return AArch64::STPSi;
329  case AArch64::STRDui:
330  case AArch64::STURDi:
331  return AArch64::STPDi;
332  case AArch64::STRQui:
333  case AArch64::STURQi:
334  return AArch64::STPQi;
335  case AArch64::STRWui:
336  case AArch64::STURWi:
337  return AArch64::STPWi;
338  case AArch64::STRXui:
339  case AArch64::STURXi:
340  return AArch64::STPXi;
341  case AArch64::LDRSui:
342  case AArch64::LDURSi:
343  return AArch64::LDPSi;
344  case AArch64::LDRDui:
345  case AArch64::LDURDi:
346  return AArch64::LDPDi;
347  case AArch64::LDRQui:
348  case AArch64::LDURQi:
349  return AArch64::LDPQi;
350  case AArch64::LDRWui:
351  case AArch64::LDURWi:
352  return AArch64::LDPWi;
353  case AArch64::LDRXui:
354  case AArch64::LDURXi:
355  return AArch64::LDPXi;
356  case AArch64::LDRSWui:
357  case AArch64::LDURSWi:
358  return AArch64::LDPSWi;
359  }
360 }
361 
364  unsigned LdOpc = LoadInst.getOpcode();
365  unsigned StOpc = StoreInst.getOpcode();
366  switch (LdOpc) {
367  default:
368  llvm_unreachable("Unsupported load instruction!");
369  case AArch64::LDRBBui:
370  return StOpc == AArch64::STRBBui || StOpc == AArch64::STRHHui ||
371  StOpc == AArch64::STRWui || StOpc == AArch64::STRXui;
372  case AArch64::LDURBBi:
373  return StOpc == AArch64::STURBBi || StOpc == AArch64::STURHHi ||
374  StOpc == AArch64::STURWi || StOpc == AArch64::STURXi;
375  case AArch64::LDRHHui:
376  return StOpc == AArch64::STRHHui || StOpc == AArch64::STRWui ||
377  StOpc == AArch64::STRXui;
378  case AArch64::LDURHHi:
379  return StOpc == AArch64::STURHHi || StOpc == AArch64::STURWi ||
380  StOpc == AArch64::STURXi;
381  case AArch64::LDRWui:
382  return StOpc == AArch64::STRWui || StOpc == AArch64::STRXui;
383  case AArch64::LDURWi:
384  return StOpc == AArch64::STURWi || StOpc == AArch64::STURXi;
385  case AArch64::LDRXui:
386  return StOpc == AArch64::STRXui;
387  case AArch64::LDURXi:
388  return StOpc == AArch64::STURXi;
389  }
390 }
391 
392 static unsigned getPreIndexedOpcode(unsigned Opc) {
393  // FIXME: We don't currently support creating pre-indexed loads/stores when
394  // the load or store is the unscaled version. If we decide to perform such an
395  // optimization in the future the cases for the unscaled loads/stores will
396  // need to be added here.
397  switch (Opc) {
398  default:
399  llvm_unreachable("Opcode has no pre-indexed equivalent!");
400  case AArch64::STRSui:
401  return AArch64::STRSpre;
402  case AArch64::STRDui:
403  return AArch64::STRDpre;
404  case AArch64::STRQui:
405  return AArch64::STRQpre;
406  case AArch64::STRBBui:
407  return AArch64::STRBBpre;
408  case AArch64::STRHHui:
409  return AArch64::STRHHpre;
410  case AArch64::STRWui:
411  return AArch64::STRWpre;
412  case AArch64::STRXui:
413  return AArch64::STRXpre;
414  case AArch64::LDRSui:
415  return AArch64::LDRSpre;
416  case AArch64::LDRDui:
417  return AArch64::LDRDpre;
418  case AArch64::LDRQui:
419  return AArch64::LDRQpre;
420  case AArch64::LDRBBui:
421  return AArch64::LDRBBpre;
422  case AArch64::LDRHHui:
423  return AArch64::LDRHHpre;
424  case AArch64::LDRWui:
425  return AArch64::LDRWpre;
426  case AArch64::LDRXui:
427  return AArch64::LDRXpre;
428  case AArch64::LDRSWui:
429  return AArch64::LDRSWpre;
430  case AArch64::LDPSi:
431  return AArch64::LDPSpre;
432  case AArch64::LDPSWi:
433  return AArch64::LDPSWpre;
434  case AArch64::LDPDi:
435  return AArch64::LDPDpre;
436  case AArch64::LDPQi:
437  return AArch64::LDPQpre;
438  case AArch64::LDPWi:
439  return AArch64::LDPWpre;
440  case AArch64::LDPXi:
441  return AArch64::LDPXpre;
442  case AArch64::STPSi:
443  return AArch64::STPSpre;
444  case AArch64::STPDi:
445  return AArch64::STPDpre;
446  case AArch64::STPQi:
447  return AArch64::STPQpre;
448  case AArch64::STPWi:
449  return AArch64::STPWpre;
450  case AArch64::STPXi:
451  return AArch64::STPXpre;
452  }
453 }
454 
455 static unsigned getPostIndexedOpcode(unsigned Opc) {
456  switch (Opc) {
457  default:
458  llvm_unreachable("Opcode has no post-indexed wise equivalent!");
459  case AArch64::STRSui:
460  case AArch64::STURSi:
461  return AArch64::STRSpost;
462  case AArch64::STRDui:
463  case AArch64::STURDi:
464  return AArch64::STRDpost;
465  case AArch64::STRQui:
466  case AArch64::STURQi:
467  return AArch64::STRQpost;
468  case AArch64::STRBBui:
469  return AArch64::STRBBpost;
470  case AArch64::STRHHui:
471  return AArch64::STRHHpost;
472  case AArch64::STRWui:
473  case AArch64::STURWi:
474  return AArch64::STRWpost;
475  case AArch64::STRXui:
476  case AArch64::STURXi:
477  return AArch64::STRXpost;
478  case AArch64::LDRSui:
479  case AArch64::LDURSi:
480  return AArch64::LDRSpost;
481  case AArch64::LDRDui:
482  case AArch64::LDURDi:
483  return AArch64::LDRDpost;
484  case AArch64::LDRQui:
485  case AArch64::LDURQi:
486  return AArch64::LDRQpost;
487  case AArch64::LDRBBui:
488  return AArch64::LDRBBpost;
489  case AArch64::LDRHHui:
490  return AArch64::LDRHHpost;
491  case AArch64::LDRWui:
492  case AArch64::LDURWi:
493  return AArch64::LDRWpost;
494  case AArch64::LDRXui:
495  case AArch64::LDURXi:
496  return AArch64::LDRXpost;
497  case AArch64::LDRSWui:
498  return AArch64::LDRSWpost;
499  case AArch64::LDPSi:
500  return AArch64::LDPSpost;
501  case AArch64::LDPSWi:
502  return AArch64::LDPSWpost;
503  case AArch64::LDPDi:
504  return AArch64::LDPDpost;
505  case AArch64::LDPQi:
506  return AArch64::LDPQpost;
507  case AArch64::LDPWi:
508  return AArch64::LDPWpost;
509  case AArch64::LDPXi:
510  return AArch64::LDPXpost;
511  case AArch64::STPSi:
512  return AArch64::STPSpost;
513  case AArch64::STPDi:
514  return AArch64::STPDpost;
515  case AArch64::STPQi:
516  return AArch64::STPQpost;
517  case AArch64::STPWi:
518  return AArch64::STPWpost;
519  case AArch64::STPXi:
520  return AArch64::STPXpost;
521  }
522 }
523 
524 static bool isPairedLdSt(const MachineInstr &MI) {
525  switch (MI.getOpcode()) {
526  default:
527  return false;
528  case AArch64::LDPSi:
529  case AArch64::LDPSWi:
530  case AArch64::LDPDi:
531  case AArch64::LDPQi:
532  case AArch64::LDPWi:
533  case AArch64::LDPXi:
534  case AArch64::STPSi:
535  case AArch64::STPDi:
536  case AArch64::STPQi:
537  case AArch64::STPWi:
538  case AArch64::STPXi:
539  return true;
540  }
541 }
542 
544  unsigned PairedRegOp = 0) {
545  assert(PairedRegOp < 2 && "Unexpected register operand idx.");
546  unsigned Idx = isPairedLdSt(MI) ? PairedRegOp : 0;
547  return MI.getOperand(Idx);
548 }
549 
551  unsigned Idx = isPairedLdSt(MI) ? 2 : 1;
552  return MI.getOperand(Idx);
553 }
554 
556  unsigned Idx = isPairedLdSt(MI) ? 3 : 2;
557  return MI.getOperand(Idx);
558 }
559 
562  const AArch64InstrInfo *TII) {
563  assert(isMatchingStore(LoadInst, StoreInst) && "Expect only matched ld/st.");
564  int LoadSize = getMemScale(LoadInst);
565  int StoreSize = getMemScale(StoreInst);
566  int UnscaledStOffset = TII->isUnscaledLdSt(StoreInst)
567  ? getLdStOffsetOp(StoreInst).getImm()
568  : getLdStOffsetOp(StoreInst).getImm() * StoreSize;
569  int UnscaledLdOffset = TII->isUnscaledLdSt(LoadInst)
570  ? getLdStOffsetOp(LoadInst).getImm()
571  : getLdStOffsetOp(LoadInst).getImm() * LoadSize;
572  return (UnscaledStOffset <= UnscaledLdOffset) &&
573  (UnscaledLdOffset + LoadSize <= (UnscaledStOffset + StoreSize));
574 }
575 
577  unsigned Opc = MI.getOpcode();
578  return (Opc == AArch64::STRWui || Opc == AArch64::STURWi ||
579  isNarrowStore(Opc)) &&
580  getLdStRegOp(MI).getReg() == AArch64::WZR;
581 }
582 
584  switch (MI.getOpcode()) {
585  default:
586  return false;
587  // Scaled instructions.
588  case AArch64::LDRBBui:
589  case AArch64::LDRHHui:
590  case AArch64::LDRWui:
591  case AArch64::LDRXui:
592  // Unscaled instructions.
593  case AArch64::LDURBBi:
594  case AArch64::LDURHHi:
595  case AArch64::LDURWi:
596  case AArch64::LDURXi:
597  return true;
598  }
599 }
600 
602  unsigned Opc = MI.getOpcode();
603  switch (Opc) {
604  default:
605  return false;
606  // Scaled instructions.
607  case AArch64::STRSui:
608  case AArch64::STRDui:
609  case AArch64::STRQui:
610  case AArch64::STRXui:
611  case AArch64::STRWui:
612  case AArch64::STRHHui:
613  case AArch64::STRBBui:
614  case AArch64::LDRSui:
615  case AArch64::LDRDui:
616  case AArch64::LDRQui:
617  case AArch64::LDRXui:
618  case AArch64::LDRWui:
619  case AArch64::LDRHHui:
620  case AArch64::LDRBBui:
621  // Unscaled instructions.
622  case AArch64::STURSi:
623  case AArch64::STURDi:
624  case AArch64::STURQi:
625  case AArch64::STURWi:
626  case AArch64::STURXi:
627  case AArch64::LDURSi:
628  case AArch64::LDURDi:
629  case AArch64::LDURQi:
630  case AArch64::LDURWi:
631  case AArch64::LDURXi:
632  // Paired instructions.
633  case AArch64::LDPSi:
634  case AArch64::LDPSWi:
635  case AArch64::LDPDi:
636  case AArch64::LDPQi:
637  case AArch64::LDPWi:
638  case AArch64::LDPXi:
639  case AArch64::STPSi:
640  case AArch64::STPDi:
641  case AArch64::STPQi:
642  case AArch64::STPWi:
643  case AArch64::STPXi:
644  // Make sure this is a reg+imm (as opposed to an address reloc).
645  if (!getLdStOffsetOp(MI).isImm())
646  return false;
647 
648  return true;
649  }
650 }
651 
653 AArch64LoadStoreOpt::mergeNarrowZeroStores(MachineBasicBlock::iterator I,
655  const LdStPairFlags &Flags) {
657  "Expected promotable zero stores.");
658 
660  ++NextI;
661  // If NextI is the second of the two instructions to be merged, we need
662  // to skip one further. Either way we merge will invalidate the iterator,
663  // and we don't need to scan the new instruction, as it's a pairwise
664  // instruction, which we're not considering for further action anyway.
665  if (NextI == MergeMI)
666  ++NextI;
667 
668  unsigned Opc = I->getOpcode();
669  bool IsScaled = !TII->isUnscaledLdSt(Opc);
670  int OffsetStride = IsScaled ? 1 : getMemScale(*I);
671 
672  bool MergeForward = Flags.getMergeForward();
673  // Insert our new paired instruction after whichever of the paired
674  // instructions MergeForward indicates.
675  MachineBasicBlock::iterator InsertionPoint = MergeForward ? MergeMI : I;
676  // Also based on MergeForward is from where we copy the base register operand
677  // so we get the flags compatible with the input code.
678  const MachineOperand &BaseRegOp =
679  MergeForward ? getLdStBaseOp(*MergeMI) : getLdStBaseOp(*I);
680 
681  // Which register is Rt and which is Rt2 depends on the offset order.
682  MachineInstr *RtMI;
683  if (getLdStOffsetOp(*I).getImm() ==
684  getLdStOffsetOp(*MergeMI).getImm() + OffsetStride)
685  RtMI = &*MergeMI;
686  else
687  RtMI = &*I;
688 
689  int OffsetImm = getLdStOffsetOp(*RtMI).getImm();
690  // Change the scaled offset from small to large type.
691  if (IsScaled) {
692  assert(((OffsetImm & 1) == 0) && "Unexpected offset to merge");
693  OffsetImm /= 2;
694  }
695 
696  // Construct the new instruction.
697  DebugLoc DL = I->getDebugLoc();
698  MachineBasicBlock *MBB = I->getParent();
700  MIB = BuildMI(*MBB, InsertionPoint, DL, TII->get(getMatchingWideOpcode(Opc)))
701  .addReg(isNarrowStore(Opc) ? AArch64::WZR : AArch64::XZR)
702  .add(BaseRegOp)
703  .addImm(OffsetImm)
704  .cloneMergedMemRefs({&*I, &*MergeMI})
705  .setMIFlags(I->mergeFlagsWith(*MergeMI));
706  (void)MIB;
707 
708  LLVM_DEBUG(dbgs() << "Creating wider store. Replacing instructions:\n ");
709  LLVM_DEBUG(I->print(dbgs()));
710  LLVM_DEBUG(dbgs() << " ");
711  LLVM_DEBUG(MergeMI->print(dbgs()));
712  LLVM_DEBUG(dbgs() << " with instruction:\n ");
713  LLVM_DEBUG(((MachineInstr *)MIB)->print(dbgs()));
714  LLVM_DEBUG(dbgs() << "\n");
715 
716  // Erase the old instructions.
717  I->eraseFromParent();
718  MergeMI->eraseFromParent();
719  return NextI;
720 }
721 
723 AArch64LoadStoreOpt::mergePairedInsns(MachineBasicBlock::iterator I,
725  const LdStPairFlags &Flags) {
727  ++NextI;
728  // If NextI is the second of the two instructions to be merged, we need
729  // to skip one further. Either way we merge will invalidate the iterator,
730  // and we don't need to scan the new instruction, as it's a pairwise
731  // instruction, which we're not considering for further action anyway.
732  if (NextI == Paired)
733  ++NextI;
734 
735  int SExtIdx = Flags.getSExtIdx();
736  unsigned Opc =
737  SExtIdx == -1 ? I->getOpcode() : getMatchingNonSExtOpcode(I->getOpcode());
738  bool IsUnscaled = TII->isUnscaledLdSt(Opc);
739  int OffsetStride = IsUnscaled ? getMemScale(*I) : 1;
740 
741  bool MergeForward = Flags.getMergeForward();
742  // Insert our new paired instruction after whichever of the paired
743  // instructions MergeForward indicates.
744  MachineBasicBlock::iterator InsertionPoint = MergeForward ? Paired : I;
745  // Also based on MergeForward is from where we copy the base register operand
746  // so we get the flags compatible with the input code.
747  const MachineOperand &BaseRegOp =
748  MergeForward ? getLdStBaseOp(*Paired) : getLdStBaseOp(*I);
749 
750  int Offset = getLdStOffsetOp(*I).getImm();
751  int PairedOffset = getLdStOffsetOp(*Paired).getImm();
752  bool PairedIsUnscaled = TII->isUnscaledLdSt(Paired->getOpcode());
753  if (IsUnscaled != PairedIsUnscaled) {
754  // We're trying to pair instructions that differ in how they are scaled. If
755  // I is scaled then scale the offset of Paired accordingly. Otherwise, do
756  // the opposite (i.e., make Paired's offset unscaled).
757  int MemSize = getMemScale(*Paired);
758  if (PairedIsUnscaled) {
759  // If the unscaled offset isn't a multiple of the MemSize, we can't
760  // pair the operations together.
761  assert(!(PairedOffset % getMemScale(*Paired)) &&
762  "Offset should be a multiple of the stride!");
763  PairedOffset /= MemSize;
764  } else {
765  PairedOffset *= MemSize;
766  }
767  }
768 
769  // Which register is Rt and which is Rt2 depends on the offset order.
770  MachineInstr *RtMI, *Rt2MI;
771  if (Offset == PairedOffset + OffsetStride) {
772  RtMI = &*Paired;
773  Rt2MI = &*I;
774  // Here we swapped the assumption made for SExtIdx.
775  // I.e., we turn ldp I, Paired into ldp Paired, I.
776  // Update the index accordingly.
777  if (SExtIdx != -1)
778  SExtIdx = (SExtIdx + 1) % 2;
779  } else {
780  RtMI = &*I;
781  Rt2MI = &*Paired;
782  }
783  int OffsetImm = getLdStOffsetOp(*RtMI).getImm();
784  // Scale the immediate offset, if necessary.
785  if (TII->isUnscaledLdSt(RtMI->getOpcode())) {
786  assert(!(OffsetImm % getMemScale(*RtMI)) &&
787  "Unscaled offset cannot be scaled.");
788  OffsetImm /= getMemScale(*RtMI);
789  }
790 
791  // Construct the new instruction.
793  DebugLoc DL = I->getDebugLoc();
794  MachineBasicBlock *MBB = I->getParent();
795  MachineOperand RegOp0 = getLdStRegOp(*RtMI);
796  MachineOperand RegOp1 = getLdStRegOp(*Rt2MI);
797  // Kill flags may become invalid when moving stores for pairing.
798  if (RegOp0.isUse()) {
799  if (!MergeForward) {
800  // Clear kill flags on store if moving upwards. Example:
801  // STRWui %w0, ...
802  // USE %w1
803  // STRWui kill %w1 ; need to clear kill flag when moving STRWui upwards
804  RegOp0.setIsKill(false);
805  RegOp1.setIsKill(false);
806  } else {
807  // Clear kill flags of the first stores register. Example:
808  // STRWui %w1, ...
809  // USE kill %w1 ; need to clear kill flag when moving STRWui downwards
810  // STRW %w0
811  unsigned Reg = getLdStRegOp(*I).getReg();
812  for (MachineInstr &MI : make_range(std::next(I), Paired))
813  MI.clearRegisterKills(Reg, TRI);
814  }
815  }
816  MIB = BuildMI(*MBB, InsertionPoint, DL, TII->get(getMatchingPairOpcode(Opc)))
817  .add(RegOp0)
818  .add(RegOp1)
819  .add(BaseRegOp)
820  .addImm(OffsetImm)
821  .cloneMergedMemRefs({&*I, &*Paired})
822  .setMIFlags(I->mergeFlagsWith(*Paired));
823 
824  (void)MIB;
825 
826  LLVM_DEBUG(
827  dbgs() << "Creating pair load/store. Replacing instructions:\n ");
828  LLVM_DEBUG(I->print(dbgs()));
829  LLVM_DEBUG(dbgs() << " ");
830  LLVM_DEBUG(Paired->print(dbgs()));
831  LLVM_DEBUG(dbgs() << " with instruction:\n ");
832  if (SExtIdx != -1) {
833  // Generate the sign extension for the proper result of the ldp.
834  // I.e., with X1, that would be:
835  // %w1 = KILL %w1, implicit-def %x1
836  // %x1 = SBFMXri killed %x1, 0, 31
837  MachineOperand &DstMO = MIB->getOperand(SExtIdx);
838  // Right now, DstMO has the extended register, since it comes from an
839  // extended opcode.
840  unsigned DstRegX = DstMO.getReg();
841  // Get the W variant of that register.
842  unsigned DstRegW = TRI->getSubReg(DstRegX, AArch64::sub_32);
843  // Update the result of LDP to use the W instead of the X variant.
844  DstMO.setReg(DstRegW);
845  LLVM_DEBUG(((MachineInstr *)MIB)->print(dbgs()));
846  LLVM_DEBUG(dbgs() << "\n");
847  // Make the machine verifier happy by providing a definition for
848  // the X register.
849  // Insert this definition right after the generated LDP, i.e., before
850  // InsertionPoint.
851  MachineInstrBuilder MIBKill =
852  BuildMI(*MBB, InsertionPoint, DL, TII->get(TargetOpcode::KILL), DstRegW)
853  .addReg(DstRegW)
854  .addReg(DstRegX, RegState::Define);
855  MIBKill->getOperand(2).setImplicit();
856  // Create the sign extension.
857  MachineInstrBuilder MIBSXTW =
858  BuildMI(*MBB, InsertionPoint, DL, TII->get(AArch64::SBFMXri), DstRegX)
859  .addReg(DstRegX)
860  .addImm(0)
861  .addImm(31);
862  (void)MIBSXTW;
863  LLVM_DEBUG(dbgs() << " Extend operand:\n ");
864  LLVM_DEBUG(((MachineInstr *)MIBSXTW)->print(dbgs()));
865  } else {
866  LLVM_DEBUG(((MachineInstr *)MIB)->print(dbgs()));
867  }
868  LLVM_DEBUG(dbgs() << "\n");
869 
870  // Erase the old instructions.
871  I->eraseFromParent();
872  Paired->eraseFromParent();
873 
874  return NextI;
875 }
876 
878 AArch64LoadStoreOpt::promoteLoadFromStore(MachineBasicBlock::iterator LoadI,
880  MachineBasicBlock::iterator NextI = LoadI;
881  ++NextI;
882 
883  int LoadSize = getMemScale(*LoadI);
884  int StoreSize = getMemScale(*StoreI);
885  unsigned LdRt = getLdStRegOp(*LoadI).getReg();
886  const MachineOperand &StMO = getLdStRegOp(*StoreI);
887  unsigned StRt = getLdStRegOp(*StoreI).getReg();
888  bool IsStoreXReg = TRI->getRegClass(AArch64::GPR64RegClassID)->contains(StRt);
889 
890  assert((IsStoreXReg ||
891  TRI->getRegClass(AArch64::GPR32RegClassID)->contains(StRt)) &&
892  "Unexpected RegClass");
893 
894  MachineInstr *BitExtMI;
895  if (LoadSize == StoreSize && (LoadSize == 4 || LoadSize == 8)) {
896  // Remove the load, if the destination register of the loads is the same
897  // register for stored value.
898  if (StRt == LdRt && LoadSize == 8) {
899  for (MachineInstr &MI : make_range(StoreI->getIterator(),
900  LoadI->getIterator())) {
901  if (MI.killsRegister(StRt, TRI)) {
902  MI.clearRegisterKills(StRt, TRI);
903  break;
904  }
905  }
906  LLVM_DEBUG(dbgs() << "Remove load instruction:\n ");
907  LLVM_DEBUG(LoadI->print(dbgs()));
908  LLVM_DEBUG(dbgs() << "\n");
909  LoadI->eraseFromParent();
910  return NextI;
911  }
912  // Replace the load with a mov if the load and store are in the same size.
913  BitExtMI =
914  BuildMI(*LoadI->getParent(), LoadI, LoadI->getDebugLoc(),
915  TII->get(IsStoreXReg ? AArch64::ORRXrs : AArch64::ORRWrs), LdRt)
916  .addReg(IsStoreXReg ? AArch64::XZR : AArch64::WZR)
917  .add(StMO)
919  .setMIFlags(LoadI->getFlags());
920  } else {
921  // FIXME: Currently we disable this transformation in big-endian targets as
922  // performance and correctness are verified only in little-endian.
923  if (!Subtarget->isLittleEndian())
924  return NextI;
925  bool IsUnscaled = TII->isUnscaledLdSt(*LoadI);
926  assert(IsUnscaled == TII->isUnscaledLdSt(*StoreI) &&
927  "Unsupported ld/st match");
928  assert(LoadSize <= StoreSize && "Invalid load size");
929  int UnscaledLdOffset = IsUnscaled
930  ? getLdStOffsetOp(*LoadI).getImm()
931  : getLdStOffsetOp(*LoadI).getImm() * LoadSize;
932  int UnscaledStOffset = IsUnscaled
933  ? getLdStOffsetOp(*StoreI).getImm()
934  : getLdStOffsetOp(*StoreI).getImm() * StoreSize;
935  int Width = LoadSize * 8;
936  int Immr = 8 * (UnscaledLdOffset - UnscaledStOffset);
937  int Imms = Immr + Width - 1;
938  unsigned DestReg = IsStoreXReg
939  ? TRI->getMatchingSuperReg(LdRt, AArch64::sub_32,
940  &AArch64::GPR64RegClass)
941  : LdRt;
942 
943  assert((UnscaledLdOffset >= UnscaledStOffset &&
944  (UnscaledLdOffset + LoadSize) <= UnscaledStOffset + StoreSize) &&
945  "Invalid offset");
946 
947  Immr = 8 * (UnscaledLdOffset - UnscaledStOffset);
948  Imms = Immr + Width - 1;
949  if (UnscaledLdOffset == UnscaledStOffset) {
950  uint32_t AndMaskEncoded = ((IsStoreXReg ? 1 : 0) << 12) // N
951  | ((Immr) << 6) // immr
952  | ((Imms) << 0) // imms
953  ;
954 
955  BitExtMI =
956  BuildMI(*LoadI->getParent(), LoadI, LoadI->getDebugLoc(),
957  TII->get(IsStoreXReg ? AArch64::ANDXri : AArch64::ANDWri),
958  DestReg)
959  .add(StMO)
960  .addImm(AndMaskEncoded)
961  .setMIFlags(LoadI->getFlags());
962  } else {
963  BitExtMI =
964  BuildMI(*LoadI->getParent(), LoadI, LoadI->getDebugLoc(),
965  TII->get(IsStoreXReg ? AArch64::UBFMXri : AArch64::UBFMWri),
966  DestReg)
967  .add(StMO)
968  .addImm(Immr)
969  .addImm(Imms)
970  .setMIFlags(LoadI->getFlags());
971  }
972  }
973 
974  // Clear kill flags between store and load.
975  for (MachineInstr &MI : make_range(StoreI->getIterator(),
976  BitExtMI->getIterator()))
977  if (MI.killsRegister(StRt, TRI)) {
978  MI.clearRegisterKills(StRt, TRI);
979  break;
980  }
981 
982  LLVM_DEBUG(dbgs() << "Promoting load by replacing :\n ");
983  LLVM_DEBUG(StoreI->print(dbgs()));
984  LLVM_DEBUG(dbgs() << " ");
985  LLVM_DEBUG(LoadI->print(dbgs()));
986  LLVM_DEBUG(dbgs() << " with instructions:\n ");
987  LLVM_DEBUG(StoreI->print(dbgs()));
988  LLVM_DEBUG(dbgs() << " ");
989  LLVM_DEBUG((BitExtMI)->print(dbgs()));
990  LLVM_DEBUG(dbgs() << "\n");
991 
992  // Erase the old instructions.
993  LoadI->eraseFromParent();
994  return NextI;
995 }
996 
997 static bool inBoundsForPair(bool IsUnscaled, int Offset, int OffsetStride) {
998  // Convert the byte-offset used by unscaled into an "element" offset used
999  // by the scaled pair load/store instructions.
1000  if (IsUnscaled) {
1001  // If the byte-offset isn't a multiple of the stride, there's no point
1002  // trying to match it.
1003  if (Offset % OffsetStride)
1004  return false;
1005  Offset /= OffsetStride;
1006  }
1007  return Offset <= 63 && Offset >= -64;
1008 }
1009 
1010 // Do alignment, specialized to power of 2 and for signed ints,
1011 // avoiding having to do a C-style cast from uint_64t to int when
1012 // using alignTo from include/llvm/Support/MathExtras.h.
1013 // FIXME: Move this function to include/MathExtras.h?
1014 static int alignTo(int Num, int PowOf2) {
1015  return (Num + PowOf2 - 1) & ~(PowOf2 - 1);
1016 }
1017 
1018 static bool mayAlias(MachineInstr &MIa, MachineInstr &MIb,
1019  AliasAnalysis *AA) {
1020  // One of the instructions must modify memory.
1021  if (!MIa.mayStore() && !MIb.mayStore())
1022  return false;
1023 
1024  // Both instructions must be memory operations.
1025  if (!MIa.mayLoadOrStore() && !MIb.mayLoadOrStore())
1026  return false;
1027 
1028  return MIa.mayAlias(AA, MIb, /*UseTBAA*/false);
1029 }
1030 
1031 static bool mayAlias(MachineInstr &MIa,
1033  AliasAnalysis *AA) {
1034  for (MachineInstr *MIb : MemInsns)
1035  if (mayAlias(MIa, *MIb, AA))
1036  return true;
1037 
1038  return false;
1039 }
1040 
1041 bool AArch64LoadStoreOpt::findMatchingStore(
1042  MachineBasicBlock::iterator I, unsigned Limit,
1043  MachineBasicBlock::iterator &StoreI) {
1044  MachineBasicBlock::iterator B = I->getParent()->begin();
1046  MachineInstr &LoadMI = *I;
1047  unsigned BaseReg = getLdStBaseOp(LoadMI).getReg();
1048 
1049  // If the load is the first instruction in the block, there's obviously
1050  // not any matching store.
1051  if (MBBI == B)
1052  return false;
1053 
1054  // Track which register units have been modified and used between the first
1055  // insn and the second insn.
1056  ModifiedRegUnits.clear();
1057  UsedRegUnits.clear();
1058 
1059  unsigned Count = 0;
1060  do {
1061  --MBBI;
1062  MachineInstr &MI = *MBBI;
1063 
1064  // Don't count transient instructions towards the search limit since there
1065  // may be different numbers of them if e.g. debug information is present.
1066  if (!MI.isTransient())
1067  ++Count;
1068 
1069  // If the load instruction reads directly from the address to which the
1070  // store instruction writes and the stored value is not modified, we can
1071  // promote the load. Since we do not handle stores with pre-/post-index,
1072  // it's unnecessary to check if BaseReg is modified by the store itself.
1073  if (MI.mayStore() && isMatchingStore(LoadMI, MI) &&
1074  BaseReg == getLdStBaseOp(MI).getReg() &&
1075  isLdOffsetInRangeOfSt(LoadMI, MI, TII) &&
1076  ModifiedRegUnits.available(getLdStRegOp(MI).getReg())) {
1077  StoreI = MBBI;
1078  return true;
1079  }
1080 
1081  if (MI.isCall())
1082  return false;
1083 
1084  // Update modified / uses register units.
1085  LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits, UsedRegUnits, TRI);
1086 
1087  // Otherwise, if the base register is modified, we have no match, so
1088  // return early.
1089  if (!ModifiedRegUnits.available(BaseReg))
1090  return false;
1091 
1092  // If we encounter a store aliased with the load, return early.
1093  if (MI.mayStore() && mayAlias(LoadMI, MI, AA))
1094  return false;
1095  } while (MBBI != B && Count < Limit);
1096  return false;
1097 }
1098 
1099 // Returns true if FirstMI and MI are candidates for merging or pairing.
1100 // Otherwise, returns false.
1102  LdStPairFlags &Flags,
1103  const AArch64InstrInfo *TII) {
1104  // If this is volatile or if pairing is suppressed, not a candidate.
1105  if (MI.hasOrderedMemoryRef() || TII->isLdStPairSuppressed(MI))
1106  return false;
1107 
1108  // We should have already checked FirstMI for pair suppression and volatility.
1109  assert(!FirstMI.hasOrderedMemoryRef() &&
1110  !TII->isLdStPairSuppressed(FirstMI) &&
1111  "FirstMI shouldn't get here if either of these checks are true.");
1112 
1113  unsigned OpcA = FirstMI.getOpcode();
1114  unsigned OpcB = MI.getOpcode();
1115 
1116  // Opcodes match: nothing more to check.
1117  if (OpcA == OpcB)
1118  return true;
1119 
1120  // Try to match a sign-extended load/store with a zero-extended load/store.
1121  bool IsValidLdStrOpc, PairIsValidLdStrOpc;
1122  unsigned NonSExtOpc = getMatchingNonSExtOpcode(OpcA, &IsValidLdStrOpc);
1123  assert(IsValidLdStrOpc &&
1124  "Given Opc should be a Load or Store with an immediate");
1125  // OpcA will be the first instruction in the pair.
1126  if (NonSExtOpc == getMatchingNonSExtOpcode(OpcB, &PairIsValidLdStrOpc)) {
1127  Flags.setSExtIdx(NonSExtOpc == (unsigned)OpcA ? 1 : 0);
1128  return true;
1129  }
1130 
1131  // If the second instruction isn't even a mergable/pairable load/store, bail
1132  // out.
1133  if (!PairIsValidLdStrOpc)
1134  return false;
1135 
1136  // FIXME: We don't support merging narrow stores with mixed scaled/unscaled
1137  // offsets.
1138  if (isNarrowStore(OpcA) || isNarrowStore(OpcB))
1139  return false;
1140 
1141  // Try to match an unscaled load/store with a scaled load/store.
1142  return TII->isUnscaledLdSt(OpcA) != TII->isUnscaledLdSt(OpcB) &&
1144 
1145  // FIXME: Can we also match a mixed sext/zext unscaled/scaled pair?
1146 }
1147 
1148 /// Scan the instructions looking for a load/store that can be combined with the
1149 /// current instruction into a wider equivalent or a load/store pair.
1151 AArch64LoadStoreOpt::findMatchingInsn(MachineBasicBlock::iterator I,
1152  LdStPairFlags &Flags, unsigned Limit,
1153  bool FindNarrowMerge) {
1154  MachineBasicBlock::iterator E = I->getParent()->end();
1156  MachineInstr &FirstMI = *I;
1157  ++MBBI;
1158 
1159  bool MayLoad = FirstMI.mayLoad();
1160  bool IsUnscaled = TII->isUnscaledLdSt(FirstMI);
1161  unsigned Reg = getLdStRegOp(FirstMI).getReg();
1162  unsigned BaseReg = getLdStBaseOp(FirstMI).getReg();
1163  int Offset = getLdStOffsetOp(FirstMI).getImm();
1164  int OffsetStride = IsUnscaled ? getMemScale(FirstMI) : 1;
1165  bool IsPromotableZeroStore = isPromotableZeroStoreInst(FirstMI);
1166 
1167  // Track which register units have been modified and used between the first
1168  // insn (inclusive) and the second insn.
1169  ModifiedRegUnits.clear();
1170  UsedRegUnits.clear();
1171 
1172  // Remember any instructions that read/write memory between FirstMI and MI.
1174 
1175  for (unsigned Count = 0; MBBI != E && Count < Limit; ++MBBI) {
1176  MachineInstr &MI = *MBBI;
1177 
1178  // Don't count transient instructions towards the search limit since there
1179  // may be different numbers of them if e.g. debug information is present.
1180  if (!MI.isTransient())
1181  ++Count;
1182 
1183  Flags.setSExtIdx(-1);
1184  if (areCandidatesToMergeOrPair(FirstMI, MI, Flags, TII) &&
1185  getLdStOffsetOp(MI).isImm()) {
1186  assert(MI.mayLoadOrStore() && "Expected memory operation.");
1187  // If we've found another instruction with the same opcode, check to see
1188  // if the base and offset are compatible with our starting instruction.
1189  // These instructions all have scaled immediate operands, so we just
1190  // check for +1/-1. Make sure to check the new instruction offset is
1191  // actually an immediate and not a symbolic reference destined for
1192  // a relocation.
1193  unsigned MIBaseReg = getLdStBaseOp(MI).getReg();
1194  int MIOffset = getLdStOffsetOp(MI).getImm();
1195  bool MIIsUnscaled = TII->isUnscaledLdSt(MI);
1196  if (IsUnscaled != MIIsUnscaled) {
1197  // We're trying to pair instructions that differ in how they are scaled.
1198  // If FirstMI is scaled then scale the offset of MI accordingly.
1199  // Otherwise, do the opposite (i.e., make MI's offset unscaled).
1200  int MemSize = getMemScale(MI);
1201  if (MIIsUnscaled) {
1202  // If the unscaled offset isn't a multiple of the MemSize, we can't
1203  // pair the operations together: bail and keep looking.
1204  if (MIOffset % MemSize) {
1205  LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits,
1206  UsedRegUnits, TRI);
1207  MemInsns.push_back(&MI);
1208  continue;
1209  }
1210  MIOffset /= MemSize;
1211  } else {
1212  MIOffset *= MemSize;
1213  }
1214  }
1215 
1216  if (BaseReg == MIBaseReg && ((Offset == MIOffset + OffsetStride) ||
1217  (Offset + OffsetStride == MIOffset))) {
1218  int MinOffset = Offset < MIOffset ? Offset : MIOffset;
1219  if (FindNarrowMerge) {
1220  // If the alignment requirements of the scaled wide load/store
1221  // instruction can't express the offset of the scaled narrow input,
1222  // bail and keep looking. For promotable zero stores, allow only when
1223  // the stored value is the same (i.e., WZR).
1224  if ((!IsUnscaled && alignTo(MinOffset, 2) != MinOffset) ||
1225  (IsPromotableZeroStore && Reg != getLdStRegOp(MI).getReg())) {
1226  LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits,
1227  UsedRegUnits, TRI);
1228  MemInsns.push_back(&MI);
1229  continue;
1230  }
1231  } else {
1232  // Pairwise instructions have a 7-bit signed offset field. Single
1233  // insns have a 12-bit unsigned offset field. If the resultant
1234  // immediate offset of merging these instructions is out of range for
1235  // a pairwise instruction, bail and keep looking.
1236  if (!inBoundsForPair(IsUnscaled, MinOffset, OffsetStride)) {
1237  LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits,
1238  UsedRegUnits, TRI);
1239  MemInsns.push_back(&MI);
1240  continue;
1241  }
1242  // If the alignment requirements of the paired (scaled) instruction
1243  // can't express the offset of the unscaled input, bail and keep
1244  // looking.
1245  if (IsUnscaled && (alignTo(MinOffset, OffsetStride) != MinOffset)) {
1246  LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits,
1247  UsedRegUnits, TRI);
1248  MemInsns.push_back(&MI);
1249  continue;
1250  }
1251  }
1252  // If the destination register of the loads is the same register, bail
1253  // and keep looking. A load-pair instruction with both destination
1254  // registers the same is UNPREDICTABLE and will result in an exception.
1255  if (MayLoad && Reg == getLdStRegOp(MI).getReg()) {
1256  LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits, UsedRegUnits,
1257  TRI);
1258  MemInsns.push_back(&MI);
1259  continue;
1260  }
1261 
1262  // If the Rt of the second instruction was not modified or used between
1263  // the two instructions and none of the instructions between the second
1264  // and first alias with the second, we can combine the second into the
1265  // first.
1266  if (ModifiedRegUnits.available(getLdStRegOp(MI).getReg()) &&
1267  !(MI.mayLoad() &&
1268  !UsedRegUnits.available(getLdStRegOp(MI).getReg())) &&
1269  !mayAlias(MI, MemInsns, AA)) {
1270  Flags.setMergeForward(false);
1271  return MBBI;
1272  }
1273 
1274  // Likewise, if the Rt of the first instruction is not modified or used
1275  // between the two instructions and none of the instructions between the
1276  // first and the second alias with the first, we can combine the first
1277  // into the second.
1278  if (ModifiedRegUnits.available(getLdStRegOp(FirstMI).getReg()) &&
1279  !(MayLoad &&
1280  !UsedRegUnits.available(getLdStRegOp(FirstMI).getReg())) &&
1281  !mayAlias(FirstMI, MemInsns, AA)) {
1282  Flags.setMergeForward(true);
1283  return MBBI;
1284  }
1285  // Unable to combine these instructions due to interference in between.
1286  // Keep looking.
1287  }
1288  }
1289 
1290  // If the instruction wasn't a matching load or store. Stop searching if we
1291  // encounter a call instruction that might modify memory.
1292  if (MI.isCall())
1293  return E;
1294 
1295  // Update modified / uses register units.
1296  LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits, UsedRegUnits, TRI);
1297 
1298  // Otherwise, if the base register is modified, we have no match, so
1299  // return early.
1300  if (!ModifiedRegUnits.available(BaseReg))
1301  return E;
1302 
1303  // Update list of instructions that read/write memory.
1304  if (MI.mayLoadOrStore())
1305  MemInsns.push_back(&MI);
1306  }
1307  return E;
1308 }
1309 
1311 AArch64LoadStoreOpt::mergeUpdateInsn(MachineBasicBlock::iterator I,
1313  bool IsPreIdx) {
1314  assert((Update->getOpcode() == AArch64::ADDXri ||
1315  Update->getOpcode() == AArch64::SUBXri) &&
1316  "Unexpected base register update instruction to merge!");
1318  // Return the instruction following the merged instruction, which is
1319  // the instruction following our unmerged load. Unless that's the add/sub
1320  // instruction we're merging, in which case it's the one after that.
1321  if (++NextI == Update)
1322  ++NextI;
1323 
1324  int Value = Update->getOperand(2).getImm();
1325  assert(AArch64_AM::getShiftValue(Update->getOperand(3).getImm()) == 0 &&
1326  "Can't merge 1 << 12 offset into pre-/post-indexed load / store");
1327  if (Update->getOpcode() == AArch64::SUBXri)
1328  Value = -Value;
1329 
1330  unsigned NewOpc = IsPreIdx ? getPreIndexedOpcode(I->getOpcode())
1331  : getPostIndexedOpcode(I->getOpcode());
1332  MachineInstrBuilder MIB;
1333  if (!isPairedLdSt(*I)) {
1334  // Non-paired instruction.
1335  MIB = BuildMI(*I->getParent(), I, I->getDebugLoc(), TII->get(NewOpc))
1336  .add(getLdStRegOp(*Update))
1337  .add(getLdStRegOp(*I))
1338  .add(getLdStBaseOp(*I))
1339  .addImm(Value)
1340  .setMemRefs(I->memoperands())
1341  .setMIFlags(I->mergeFlagsWith(*Update));
1342  } else {
1343  // Paired instruction.
1344  int Scale = getMemScale(*I);
1345  MIB = BuildMI(*I->getParent(), I, I->getDebugLoc(), TII->get(NewOpc))
1346  .add(getLdStRegOp(*Update))
1347  .add(getLdStRegOp(*I, 0))
1348  .add(getLdStRegOp(*I, 1))
1349  .add(getLdStBaseOp(*I))
1350  .addImm(Value / Scale)
1351  .setMemRefs(I->memoperands())
1352  .setMIFlags(I->mergeFlagsWith(*Update));
1353  }
1354  (void)MIB;
1355 
1356  if (IsPreIdx) {
1357  ++NumPreFolded;
1358  LLVM_DEBUG(dbgs() << "Creating pre-indexed load/store.");
1359  } else {
1360  ++NumPostFolded;
1361  LLVM_DEBUG(dbgs() << "Creating post-indexed load/store.");
1362  }
1363  LLVM_DEBUG(dbgs() << " Replacing instructions:\n ");
1364  LLVM_DEBUG(I->print(dbgs()));
1365  LLVM_DEBUG(dbgs() << " ");
1366  LLVM_DEBUG(Update->print(dbgs()));
1367  LLVM_DEBUG(dbgs() << " with instruction:\n ");
1368  LLVM_DEBUG(((MachineInstr *)MIB)->print(dbgs()));
1369  LLVM_DEBUG(dbgs() << "\n");
1370 
1371  // Erase the old instructions for the block.
1372  I->eraseFromParent();
1373  Update->eraseFromParent();
1374 
1375  return NextI;
1376 }
1377 
1378 bool AArch64LoadStoreOpt::isMatchingUpdateInsn(MachineInstr &MemMI,
1379  MachineInstr &MI,
1380  unsigned BaseReg, int Offset) {
1381  switch (MI.getOpcode()) {
1382  default:
1383  break;
1384  case AArch64::SUBXri:
1385  case AArch64::ADDXri:
1386  // Make sure it's a vanilla immediate operand, not a relocation or
1387  // anything else we can't handle.
1388  if (!MI.getOperand(2).isImm())
1389  break;
1390  // Watch out for 1 << 12 shifted value.
1392  break;
1393 
1394  // The update instruction source and destination register must be the
1395  // same as the load/store base register.
1396  if (MI.getOperand(0).getReg() != BaseReg ||
1397  MI.getOperand(1).getReg() != BaseReg)
1398  break;
1399 
1400  bool IsPairedInsn = isPairedLdSt(MemMI);
1401  int UpdateOffset = MI.getOperand(2).getImm();
1402  if (MI.getOpcode() == AArch64::SUBXri)
1403  UpdateOffset = -UpdateOffset;
1404 
1405  // For non-paired load/store instructions, the immediate must fit in a
1406  // signed 9-bit integer.
1407  if (!IsPairedInsn && (UpdateOffset > 255 || UpdateOffset < -256))
1408  break;
1409 
1410  // For paired load/store instructions, the immediate must be a multiple of
1411  // the scaling factor. The scaled offset must also fit into a signed 7-bit
1412  // integer.
1413  if (IsPairedInsn) {
1414  int Scale = getMemScale(MemMI);
1415  if (UpdateOffset % Scale != 0)
1416  break;
1417 
1418  int ScaledOffset = UpdateOffset / Scale;
1419  if (ScaledOffset > 63 || ScaledOffset < -64)
1420  break;
1421  }
1422 
1423  // If we have a non-zero Offset, we check that it matches the amount
1424  // we're adding to the register.
1425  if (!Offset || Offset == UpdateOffset)
1426  return true;
1427  break;
1428  }
1429  return false;
1430 }
1431 
1432 MachineBasicBlock::iterator AArch64LoadStoreOpt::findMatchingUpdateInsnForward(
1433  MachineBasicBlock::iterator I, int UnscaledOffset, unsigned Limit) {
1434  MachineBasicBlock::iterator E = I->getParent()->end();
1435  MachineInstr &MemMI = *I;
1437 
1438  unsigned BaseReg = getLdStBaseOp(MemMI).getReg();
1439  int MIUnscaledOffset = getLdStOffsetOp(MemMI).getImm() * getMemScale(MemMI);
1440 
1441  // Scan forward looking for post-index opportunities. Updating instructions
1442  // can't be formed if the memory instruction doesn't have the offset we're
1443  // looking for.
1444  if (MIUnscaledOffset != UnscaledOffset)
1445  return E;
1446 
1447  // If the base register overlaps a destination register, we can't
1448  // merge the update.
1449  bool IsPairedInsn = isPairedLdSt(MemMI);
1450  for (unsigned i = 0, e = IsPairedInsn ? 2 : 1; i != e; ++i) {
1451  unsigned DestReg = getLdStRegOp(MemMI, i).getReg();
1452  if (DestReg == BaseReg || TRI->isSubRegister(BaseReg, DestReg))
1453  return E;
1454  }
1455 
1456  // Track which register units have been modified and used between the first
1457  // insn (inclusive) and the second insn.
1458  ModifiedRegUnits.clear();
1459  UsedRegUnits.clear();
1460  ++MBBI;
1461  for (unsigned Count = 0; MBBI != E && Count < Limit; ++MBBI) {
1462  MachineInstr &MI = *MBBI;
1463 
1464  // Don't count transient instructions towards the search limit since there
1465  // may be different numbers of them if e.g. debug information is present.
1466  if (!MI.isTransient())
1467  ++Count;
1468 
1469  // If we found a match, return it.
1470  if (isMatchingUpdateInsn(*I, MI, BaseReg, UnscaledOffset))
1471  return MBBI;
1472 
1473  // Update the status of what the instruction clobbered and used.
1474  LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits, UsedRegUnits, TRI);
1475 
1476  // Otherwise, if the base register is used or modified, we have no match, so
1477  // return early.
1478  if (!ModifiedRegUnits.available(BaseReg) ||
1479  !UsedRegUnits.available(BaseReg))
1480  return E;
1481  }
1482  return E;
1483 }
1484 
1485 MachineBasicBlock::iterator AArch64LoadStoreOpt::findMatchingUpdateInsnBackward(
1486  MachineBasicBlock::iterator I, unsigned Limit) {
1487  MachineBasicBlock::iterator B = I->getParent()->begin();
1488  MachineBasicBlock::iterator E = I->getParent()->end();
1489  MachineInstr &MemMI = *I;
1491 
1492  unsigned BaseReg = getLdStBaseOp(MemMI).getReg();
1493  int Offset = getLdStOffsetOp(MemMI).getImm();
1494 
1495  // If the load/store is the first instruction in the block, there's obviously
1496  // not any matching update. Ditto if the memory offset isn't zero.
1497  if (MBBI == B || Offset != 0)
1498  return E;
1499  // If the base register overlaps a destination register, we can't
1500  // merge the update.
1501  bool IsPairedInsn = isPairedLdSt(MemMI);
1502  for (unsigned i = 0, e = IsPairedInsn ? 2 : 1; i != e; ++i) {
1503  unsigned DestReg = getLdStRegOp(MemMI, i).getReg();
1504  if (DestReg == BaseReg || TRI->isSubRegister(BaseReg, DestReg))
1505  return E;
1506  }
1507 
1508  // Track which register units have been modified and used between the first
1509  // insn (inclusive) and the second insn.
1510  ModifiedRegUnits.clear();
1511  UsedRegUnits.clear();
1512  unsigned Count = 0;
1513  do {
1514  --MBBI;
1515  MachineInstr &MI = *MBBI;
1516 
1517  // Don't count transient instructions towards the search limit since there
1518  // may be different numbers of them if e.g. debug information is present.
1519  if (!MI.isTransient())
1520  ++Count;
1521 
1522  // If we found a match, return it.
1523  if (isMatchingUpdateInsn(*I, MI, BaseReg, Offset))
1524  return MBBI;
1525 
1526  // Update the status of what the instruction clobbered and used.
1527  LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits, UsedRegUnits, TRI);
1528 
1529  // Otherwise, if the base register is used or modified, we have no match, so
1530  // return early.
1531  if (!ModifiedRegUnits.available(BaseReg) ||
1532  !UsedRegUnits.available(BaseReg))
1533  return E;
1534  } while (MBBI != B && Count < Limit);
1535  return E;
1536 }
1537 
1538 bool AArch64LoadStoreOpt::tryToPromoteLoadFromStore(
1540  MachineInstr &MI = *MBBI;
1541  // If this is a volatile load, don't mess with it.
1542  if (MI.hasOrderedMemoryRef())
1543  return false;
1544 
1545  // Make sure this is a reg+imm.
1546  // FIXME: It is possible to extend it to handle reg+reg cases.
1547  if (!getLdStOffsetOp(MI).isImm())
1548  return false;
1549 
1550  // Look backward up to LdStLimit instructions.
1552  if (findMatchingStore(MBBI, LdStLimit, StoreI)) {
1553  ++NumLoadsFromStoresPromoted;
1554  // Promote the load. Keeping the iterator straight is a
1555  // pain, so we let the merge routine tell us what the next instruction
1556  // is after it's done mucking about.
1557  MBBI = promoteLoadFromStore(MBBI, StoreI);
1558  return true;
1559  }
1560  return false;
1561 }
1562 
1563 // Merge adjacent zero stores into a wider store.
1564 bool AArch64LoadStoreOpt::tryToMergeZeroStInst(
1566  assert(isPromotableZeroStoreInst(*MBBI) && "Expected narrow store.");
1567  MachineInstr &MI = *MBBI;
1569 
1570  if (!TII->isCandidateToMergeOrPair(MI))
1571  return false;
1572 
1573  // Look ahead up to LdStLimit instructions for a mergable instruction.
1574  LdStPairFlags Flags;
1575  MachineBasicBlock::iterator MergeMI =
1576  findMatchingInsn(MBBI, Flags, LdStLimit, /* FindNarrowMerge = */ true);
1577  if (MergeMI != E) {
1578  ++NumZeroStoresPromoted;
1579 
1580  // Keeping the iterator straight is a pain, so we let the merge routine tell
1581  // us what the next instruction is after it's done mucking about.
1582  MBBI = mergeNarrowZeroStores(MBBI, MergeMI, Flags);
1583  return true;
1584  }
1585  return false;
1586 }
1587 
1588 // Find loads and stores that can be merged into a single load or store pair
1589 // instruction.
1590 bool AArch64LoadStoreOpt::tryToPairLdStInst(MachineBasicBlock::iterator &MBBI) {
1591  MachineInstr &MI = *MBBI;
1593 
1594  if (!TII->isCandidateToMergeOrPair(MI))
1595  return false;
1596 
1597  // Early exit if the offset is not possible to match. (6 bits of positive
1598  // range, plus allow an extra one in case we find a later insn that matches
1599  // with Offset-1)
1600  bool IsUnscaled = TII->isUnscaledLdSt(MI);
1601  int Offset = getLdStOffsetOp(MI).getImm();
1602  int OffsetStride = IsUnscaled ? getMemScale(MI) : 1;
1603  // Allow one more for offset.
1604  if (Offset > 0)
1605  Offset -= OffsetStride;
1606  if (!inBoundsForPair(IsUnscaled, Offset, OffsetStride))
1607  return false;
1608 
1609  // Look ahead up to LdStLimit instructions for a pairable instruction.
1610  LdStPairFlags Flags;
1612  findMatchingInsn(MBBI, Flags, LdStLimit, /* FindNarrowMerge = */ false);
1613  if (Paired != E) {
1614  ++NumPairCreated;
1615  if (TII->isUnscaledLdSt(MI))
1616  ++NumUnscaledPairCreated;
1617  // Keeping the iterator straight is a pain, so we let the merge routine tell
1618  // us what the next instruction is after it's done mucking about.
1619  MBBI = mergePairedInsns(MBBI, Paired, Flags);
1620  return true;
1621  }
1622  return false;
1623 }
1624 
1625 bool AArch64LoadStoreOpt::tryToMergeLdStUpdate
1626  (MachineBasicBlock::iterator &MBBI) {
1627  MachineInstr &MI = *MBBI;
1630 
1631  // Look forward to try to form a post-index instruction. For example,
1632  // ldr x0, [x20]
1633  // add x20, x20, #32
1634  // merged into:
1635  // ldr x0, [x20], #32
1636  Update = findMatchingUpdateInsnForward(MBBI, 0, UpdateLimit);
1637  if (Update != E) {
1638  // Merge the update into the ld/st.
1639  MBBI = mergeUpdateInsn(MBBI, Update, /*IsPreIdx=*/false);
1640  return true;
1641  }
1642 
1643  // Don't know how to handle unscaled pre/post-index versions below, so bail.
1644  if (TII->isUnscaledLdSt(MI.getOpcode()))
1645  return false;
1646 
1647  // Look back to try to find a pre-index instruction. For example,
1648  // add x0, x0, #8
1649  // ldr x1, [x0]
1650  // merged into:
1651  // ldr x1, [x0, #8]!
1652  Update = findMatchingUpdateInsnBackward(MBBI, UpdateLimit);
1653  if (Update != E) {
1654  // Merge the update into the ld/st.
1655  MBBI = mergeUpdateInsn(MBBI, Update, /*IsPreIdx=*/true);
1656  return true;
1657  }
1658 
1659  // The immediate in the load/store is scaled by the size of the memory
1660  // operation. The immediate in the add we're looking for,
1661  // however, is not, so adjust here.
1662  int UnscaledOffset = getLdStOffsetOp(MI).getImm() * getMemScale(MI);
1663 
1664  // Look forward to try to find a post-index instruction. For example,
1665  // ldr x1, [x0, #64]
1666  // add x0, x0, #64
1667  // merged into:
1668  // ldr x1, [x0, #64]!
1669  Update = findMatchingUpdateInsnForward(MBBI, UnscaledOffset, UpdateLimit);
1670  if (Update != E) {
1671  // Merge the update into the ld/st.
1672  MBBI = mergeUpdateInsn(MBBI, Update, /*IsPreIdx=*/true);
1673  return true;
1674  }
1675 
1676  return false;
1677 }
1678 
1679 bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
1680  bool EnableNarrowZeroStOpt) {
1681  bool Modified = false;
1682  // Four tranformations to do here:
1683  // 1) Find loads that directly read from stores and promote them by
1684  // replacing with mov instructions. If the store is wider than the load,
1685  // the load will be replaced with a bitfield extract.
1686  // e.g.,
1687  // str w1, [x0, #4]
1688  // ldrh w2, [x0, #6]
1689  // ; becomes
1690  // str w1, [x0, #4]
1691  // lsr w2, w1, #16
1692  for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
1693  MBBI != E;) {
1694  if (isPromotableLoadFromStore(*MBBI) && tryToPromoteLoadFromStore(MBBI))
1695  Modified = true;
1696  else
1697  ++MBBI;
1698  }
1699  // 2) Merge adjacent zero stores into a wider store.
1700  // e.g.,
1701  // strh wzr, [x0]
1702  // strh wzr, [x0, #2]
1703  // ; becomes
1704  // str wzr, [x0]
1705  // e.g.,
1706  // str wzr, [x0]
1707  // str wzr, [x0, #4]
1708  // ; becomes
1709  // str xzr, [x0]
1710  if (EnableNarrowZeroStOpt)
1711  for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
1712  MBBI != E;) {
1713  if (isPromotableZeroStoreInst(*MBBI) && tryToMergeZeroStInst(MBBI))
1714  Modified = true;
1715  else
1716  ++MBBI;
1717  }
1718  // 3) Find loads and stores that can be merged into a single load or store
1719  // pair instruction.
1720  // e.g.,
1721  // ldr x0, [x2]
1722  // ldr x1, [x2, #8]
1723  // ; becomes
1724  // ldp x0, x1, [x2]
1725  for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
1726  MBBI != E;) {
1727  if (TII->isPairableLdStInst(*MBBI) && tryToPairLdStInst(MBBI))
1728  Modified = true;
1729  else
1730  ++MBBI;
1731  }
1732  // 4) Find base register updates that can be merged into the load or store
1733  // as a base-reg writeback.
1734  // e.g.,
1735  // ldr x0, [x2]
1736  // add x2, x2, #4
1737  // ; becomes
1738  // ldr x0, [x2], #4
1739  for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
1740  MBBI != E;) {
1741  if (isMergeableLdStUpdate(*MBBI) && tryToMergeLdStUpdate(MBBI))
1742  Modified = true;
1743  else
1744  ++MBBI;
1745  }
1746 
1747  return Modified;
1748 }
1749 
1750 bool AArch64LoadStoreOpt::runOnMachineFunction(MachineFunction &Fn) {
1751  if (skipFunction(Fn.getFunction()))
1752  return false;
1753 
1754  Subtarget = &static_cast<const AArch64Subtarget &>(Fn.getSubtarget());
1755  TII = static_cast<const AArch64InstrInfo *>(Subtarget->getInstrInfo());
1756  TRI = Subtarget->getRegisterInfo();
1757  AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
1758 
1759  // Resize the modified and used register unit trackers. We do this once
1760  // per function and then clear the register units each time we optimize a load
1761  // or store.
1762  ModifiedRegUnits.init(*TRI);
1763  UsedRegUnits.init(*TRI);
1764 
1765  bool Modified = false;
1766  bool enableNarrowZeroStOpt = !Subtarget->requiresStrictAlign();
1767  for (auto &MBB : Fn)
1768  Modified |= optimizeBlock(MBB, enableNarrowZeroStOpt);
1769 
1770  return Modified;
1771 }
1772 
1773 // FIXME: Do we need/want a pre-alloc pass like ARM has to try to keep loads and
1774 // stores near one another? Note: The pre-RA instruction scheduler already has
1775 // hooks to try and schedule pairable loads/stores together to improve pairing
1776 // opportunities. Thus, pre-RA pairing pass may not be worth the effort.
1777 
1778 // FIXME: When pairing store instructions it's very possible for this pass to
1779 // hoist a store with a KILL marker above another use (without a KILL marker).
1780 // The resulting IR is invalid, but nothing uses the KILL markers after this
1781 // pass, so it's never caused a problem in practice.
1782 
1783 /// createAArch64LoadStoreOptimizationPass - returns an instance of the
1784 /// load / store optimization pass.
1786  return new AArch64LoadStoreOpt();
1787 }
const MachineInstrBuilder & add(const MachineOperand &MO) const
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
GCNRegPressure max(const GCNRegPressure &P1, const GCNRegPressure &P2)
bool isCall(QueryType Type=AnyInBundle) const
Definition: MachineInstr.h:632
This class represents lattice values for constants.
Definition: AllocatorList.h:23
static bool mayAlias(MachineInstr &MIa, MachineInstr &MIb, AliasAnalysis *AA)
static void accumulateUsedDefed(const MachineInstr &MI, LiveRegUnits &ModifiedRegUnits, LiveRegUnits &UsedRegUnits, const TargetRegisterInfo *TRI)
For a machine instruction MI, adds all register units used in UsedRegUnits and defined or clobbered i...
Definition: LiveRegUnits.h:47
void initializeAArch64LoadStoreOptPass(PassRegistry &)
void push_back(const T &Elt)
Definition: SmallVector.h:211
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
unsigned getReg() const
getReg - Returns the register number.
unsigned Reg
bool mayLoadOrStore(QueryType Type=AnyInBundle) const
Return true if this instruction could possibly read or modify memory.
Definition: MachineInstr.h:829
static bool inBoundsForPair(bool IsUnscaled, int Offset, int OffsetStride)
bool isTransient() const
Return true if this is a transient instruction that is either very likely to be eliminated during reg...
STATISTIC(NumFunctions, "Total number of functions")
unsigned const TargetRegisterInfo * TRI
A debug info location.
Definition: DebugLoc.h:33
uint64_t alignTo(uint64_t Value, uint64_t Align, uint64_t Skew=0)
Returns the next integer (mod 2**64) that is greater than or equal to Value and is a multiple of Alig...
Definition: MathExtras.h:684
An instruction for reading from memory.
Definition: Instructions.h:167
static bool isLdOffsetInRangeOfSt(MachineInstr &LoadInst, MachineInstr &StoreInst, const AArch64InstrInfo *TII)
bool isImm() const
isImm - Tests if this is a MO_Immediate operand.
static bool isLdStPairSuppressed(const MachineInstr &MI)
Return true if pairing the given load or store is hinted to be unprofitable.
static bool isUnscaledLdSt(unsigned Opc)
Return true if this is an unscaled load/store.
static bool isPromotableLoadFromStore(MachineInstr &MI)
AnalysisUsage & addRequired()
MachineFunctionPass - This class adapts the FunctionPass interface to allow convenient creation of pa...
static unsigned getMatchingPairOpcode(unsigned Opc)
const HexagonInstrInfo * TII
void setImplicit(bool Val=true)
unsigned getOpcode() const
Returns the opcode of this MachineInstr.
Definition: MachineInstr.h:408
static bool isPairedLdSt(const MachineInstr &MI)
static unsigned isMatchingStore(MachineInstr &LoadInst, MachineInstr &StoreInst)
An instruction for storing to memory.
Definition: Instructions.h:320
FunctionPass * createAArch64LoadStoreOptimizationPass()
createAArch64LoadStoreOptimizationPass - returns an instance of the load / store optimization pass...
bool mayAlias(AliasAnalysis *AA, MachineInstr &Other, bool UseTBAA)
Returns true if this instruction&#39;s memory access aliases the memory access of Other.
static unsigned getShifterImm(AArch64_AM::ShiftExtendType ST, unsigned Imm)
getShifterImm - Encode the shift type and amount: imm: 6-bit shift amount shifter: 000 ==> lsl 001 ==...
static unsigned getShiftValue(unsigned Imm)
getShiftValue - Extract the shift value.
static int getMemScale(MachineInstr &MI)
MachineInstrBuilder BuildMI(MachineFunction &MF, const DebugLoc &DL, const MCInstrDesc &MCID)
Builder interface. Specify how to create the initial instruction itself.
bool mayStore(QueryType Type=AnyInBundle) const
Return true if this instruction could possibly modify memory.
Definition: MachineInstr.h:819
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:422
#define AARCH64_LOAD_STORE_OPT_NAME
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
static unsigned getMatchingNonSExtOpcode(unsigned Opc, bool *IsValidLdStrOpc=nullptr)
const TargetSubtargetInfo & getSubtarget() const
getSubtarget - Return the subtarget for which this machine code is being compiled.
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - Subclasses that override getAnalysisUsage must call this.
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
Represent the analysis usage information of a pass.
static unsigned getMatchingWideOpcode(unsigned Opc)
static cl::opt< unsigned > LdStLimit("aarch64-load-store-scan-limit", cl::init(20), cl::Hidden)
static bool isMergeableLdStUpdate(MachineInstr &MI)
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:284
static void print(raw_ostream &Out, object::Archive::Kind Kind, T Val)
self_iterator getIterator()
Definition: ilist_node.h:81
TargetRegisterInfo base class - We assume that the target defines a static array of TargetRegisterDes...
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
void setIsKill(bool Val=true)
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
static const MachineOperand & getLdStBaseOp(const MachineInstr &MI)
MachineOperand class - Representation of each machine instruction operand.
static bool isPromotableZeroStoreInst(MachineInstr &MI)
bool hasOrderedMemoryRef() const
Return true if this instruction may have an ordered or volatile memory reference, or if the informati...
int64_t getImm() const
const Function & getFunction() const
Return the LLVM function that this machine code represents.
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
static unsigned getReg(const void *D, unsigned RC, unsigned RegNo)
const MachineBasicBlock * getParent() const
Definition: MachineInstr.h:253
MachineFunctionProperties & set(Property P)
Representation of each machine instruction.
Definition: MachineInstr.h:63
const MachineInstrBuilder & addImm(int64_t Val) const
Add a new immediate operand.
const MachineInstrBuilder & setMIFlags(unsigned Flags) const
void setReg(unsigned Reg)
Change the register this operand corresponds to.
#define I(x, y, z)
Definition: MD5.cpp:58
static const MachineOperand & getLdStRegOp(const MachineInstr &MI, unsigned PairedRegOp=0)
const MachineInstrBuilder & addReg(unsigned RegNo, unsigned flags=0, unsigned SubReg=0) const
Add a new virtual register operand.
static unsigned getPreIndexedOpcode(unsigned Opc)
A set of register units used to track register liveness.
Definition: LiveRegUnits.h:30
static const MachineOperand & getLdStOffsetOp(const MachineInstr &MI)
bool mayLoad(QueryType Type=AnyInBundle) const
Return true if this instruction could possibly read memory.
Definition: MachineInstr.h:806
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
static unsigned getPostIndexedOpcode(unsigned Opc)
LLVM Value Representation.
Definition: Value.h:72
static bool areCandidatesToMergeOrPair(MachineInstr &FirstMI, MachineInstr &MI, LdStPairFlags &Flags, const AArch64InstrInfo *TII)
IRTranslator LLVM IR MI
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
A wrapper pass to provide the legacy pass manager access to a suitably prepared AAResults object...
INITIALIZE_PASS(AArch64LoadStoreOpt, "aarch64-ldst-opt", AARCH64_LOAD_STORE_OPT_NAME, false, false) static bool isNarrowStore(unsigned Opc)
#define LLVM_DEBUG(X)
Definition: Debug.h:122
const MachineOperand & getOperand(unsigned i) const
Definition: MachineInstr.h:413
static cl::opt< unsigned > UpdateLimit("aarch64-update-scan-limit", cl::init(100), cl::Hidden)
Properties which a MachineFunction may have at a given point in time.