1//===- HexagonStoreWidening.cpp -------------------------------------------===//
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// Replace sequences of "narrow" stores to adjacent memory locations with
9// a fewer "wide" stores that have the same effect.
10// For example, replace:
11// S4_storeirb_io %100, 0, 0 ; store-immediate-byte
12// S4_storeirb_io %100, 1, 0 ; store-immediate-byte
13// with
14// S4_storeirh_io %100, 0, 0 ; store-immediate-halfword
15// The above is the general idea. The actual cases handled by the code
16// may be a bit more complex.
17// The purpose of this pass is to reduce the number of outstanding stores,
18// or as one could say, "reduce store queue pressure". Also, wide stores
19// mean fewer stores, and since there are only two memory instructions allowed
20// per packet, it also means fewer packets, and ultimately fewer cycles.
21//===---------------------------------------------------------------------===//
22
23#include "HexagonInstrInfo.h"
24#include "HexagonRegisterInfo.h"
25#include "HexagonSubtarget.h"
26#include "llvm/ADT/SmallPtrSet.h"
27#include "llvm/Analysis/AliasAnalysis.h"
28#include "llvm/Analysis/MemoryLocation.h"
29#include "llvm/CodeGen/MachineBasicBlock.h"
30#include "llvm/CodeGen/MachineFunction.h"
31#include "llvm/CodeGen/MachineFunctionPass.h"
32#include "llvm/CodeGen/MachineInstr.h"
33#include "llvm/CodeGen/MachineInstrBuilder.h"
34#include "llvm/CodeGen/MachineMemOperand.h"
35#include "llvm/CodeGen/MachineOperand.h"
36#include "llvm/CodeGen/MachineRegisterInfo.h"
37#include "llvm/IR/DebugLoc.h"
38#include "llvm/InitializePasses.h"
39#include "llvm/MC/MCInstrDesc.h"
40#include "llvm/Pass.h"
41#include "llvm/Support/Debug.h"
42#include "llvm/Support/ErrorHandling.h"
43#include "llvm/Support/MathExtras.h"
44#include "llvm/Support/raw_ostream.h"
45#include <algorithm>
46#include <cassert>
47#include <cstdint>
48#include <iterator>
49#include <vector>
50
51#define DEBUG_TYPE "hexagon-widen-stores"
52
53using namespace llvm;
54
55namespace llvm {
56
57FunctionPass *createHexagonStoreWidening();
58void initializeHexagonStoreWideningPass(PassRegistry&);
59
60} // end namespace llvm
61
62namespace {
63
64 struct HexagonStoreWidening : public MachineFunctionPass {
65 const HexagonInstrInfo *TII;
66 const HexagonRegisterInfo *TRI;
67 const MachineRegisterInfo *MRI;
68 AliasAnalysis *AA;
69 MachineFunction *MF;
70
71 public:
72 static char ID;
73
74 HexagonStoreWidening() : MachineFunctionPass(ID) {
75 initializeHexagonStoreWideningPass(*PassRegistry::getPassRegistry());
76 }
77
78 bool runOnMachineFunction(MachineFunction &MF) override;
79
80 StringRef getPassName() const override { return "Hexagon Store Widening"; }
81
82 void getAnalysisUsage(AnalysisUsage &AU) const override {
83 AU.addRequired<AAResultsWrapperPass>();
84 AU.addPreserved<AAResultsWrapperPass>();
85 MachineFunctionPass::getAnalysisUsage(AU);
86 }
87
88 static bool handledStoreType(const MachineInstr *MI);
89
90 private:
91 static const int MaxWideSize = 4;
92
93 using InstrGroup = std::vector<MachineInstr *>;
94 using InstrGroupList = std::vector<InstrGroup>;
95
96 bool instrAliased(InstrGroup &Stores, const MachineMemOperand &MMO);
97 bool instrAliased(InstrGroup &Stores, const MachineInstr *MI);
98 void createStoreGroup(MachineInstr *BaseStore, InstrGroup::iterator Begin,
99 InstrGroup::iterator End, InstrGroup &Group);
100 void createStoreGroups(MachineBasicBlock &MBB,
101 InstrGroupList &StoreGroups);
102 bool processBasicBlock(MachineBasicBlock &MBB);
103 bool processStoreGroup(InstrGroup &Group);
104 bool selectStores(InstrGroup::iterator Begin, InstrGroup::iterator End,
105 InstrGroup &OG, unsigned &TotalSize, unsigned MaxSize);
106 bool createWideStores(InstrGroup &OG, InstrGroup &NG, unsigned TotalSize);
107 bool replaceStores(InstrGroup &OG, InstrGroup &NG);
108 bool storesAreAdjacent(const MachineInstr *S1, const MachineInstr *S2);
109 };
110
111} // end anonymous namespace
112
113char HexagonStoreWidening::ID = 0;
114
115INITIALIZE_PASS_BEGIN(HexagonStoreWidening, "hexagon-widen-stores",
116 "Hexason Store Widening", false, false)
117INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
118INITIALIZE_PASS_END(HexagonStoreWidening, "hexagon-widen-stores",
119 "Hexagon Store Widening", false, false)
120
121// Some local helper functions...
122static unsigned getBaseAddressRegister(const MachineInstr *MI) {
123 const MachineOperand &MO = MI->getOperand(i: 0);
124 assert(MO.isReg() && "Expecting register operand");
125 return MO.getReg();
126}
127
128static int64_t getStoreOffset(const MachineInstr *MI) {
129 unsigned OpC = MI->getOpcode();
130 assert(HexagonStoreWidening::handledStoreType(MI) && "Unhandled opcode");
131
132 switch (OpC) {
133 case Hexagon::S4_storeirb_io:
134 case Hexagon::S4_storeirh_io:
135 case Hexagon::S4_storeiri_io: {
136 const MachineOperand &MO = MI->getOperand(i: 1);
137 assert(MO.isImm() && "Expecting immediate offset");
138 return MO.getImm();
139 }
140 }
141 dbgs() << *MI;
142 llvm_unreachable("Store offset calculation missing for a handled opcode");
143 return 0;
144}
145
146static const MachineMemOperand &getStoreTarget(const MachineInstr *MI) {
147 assert(!MI->memoperands_empty() && "Expecting memory operands");
148 return **MI->memoperands_begin();
149}
150
151// Filtering function: any stores whose opcodes are not "approved" of by
152// this function will not be subjected to widening.
153inline bool HexagonStoreWidening::handledStoreType(const MachineInstr *MI) {
154 // For now, only handle stores of immediate values.
155 // Also, reject stores to stack slots.
156 unsigned Opc = MI->getOpcode();
157 switch (Opc) {
158 case Hexagon::S4_storeirb_io:
159 case Hexagon::S4_storeirh_io:
160 case Hexagon::S4_storeiri_io:
161 // Base address must be a register. (Implement FI later.)
162 return MI->getOperand(i: 0).isReg();
163 default:
164 return false;
165 }
166}
167
168// Check if the machine memory operand MMO is aliased with any of the
169// stores in the store group Stores.
170bool HexagonStoreWidening::instrAliased(InstrGroup &Stores,
171 const MachineMemOperand &MMO) {
172 if (!MMO.getValue())
173 return true;
174
175 MemoryLocation L(MMO.getValue(), MMO.getSize(), MMO.getAAInfo());
176
177 for (auto *SI : Stores) {
178 const MachineMemOperand &SMO = getStoreTarget(MI: SI);
179 if (!SMO.getValue())
180 return true;
181
182 MemoryLocation SL(SMO.getValue(), SMO.getSize(), SMO.getAAInfo());
183 if (!AA->isNoAlias(LocA: L, LocB: SL))
184 return true;
185 }
186
187 return false;
188}
189
190// Check if the machine instruction MI accesses any storage aliased with
191// any store in the group Stores.
192bool HexagonStoreWidening::instrAliased(InstrGroup &Stores,
193 const MachineInstr *MI) {
194 for (auto &I : MI->memoperands())
195 if (instrAliased(Stores, MMO: *I))
196 return true;
197 return false;
198}
199
200// Inspect a machine basic block, and generate store groups out of stores
201// encountered in the block.
202//
203// A store group is a group of stores that use the same base register,
204// and which can be reordered within that group without altering the
205// semantics of the program. A single store group could be widened as
206// a whole, if there existed a single store instruction with the same
207// semantics as the entire group. In many cases, a single store group
208// may need more than one wide store.
209void HexagonStoreWidening::createStoreGroups(MachineBasicBlock &MBB,
210 InstrGroupList &StoreGroups) {
211 InstrGroup AllInsns;
212
213 // Copy all instruction pointers from the basic block to a temporary
214 // list. This will allow operating on the list, and modifying its
215 // elements without affecting the basic block.
216 for (auto &I : MBB)
217 AllInsns.push_back(x: &I);
218
219 // Traverse all instructions in the AllInsns list, and if we encounter
220 // a store, then try to create a store group starting at that instruction
221 // i.e. a sequence of independent stores that can be widened.
222 for (auto I = AllInsns.begin(), E = AllInsns.end(); I != E; ++I) {
223 MachineInstr *MI = *I;
224 // Skip null pointers (processed instructions).
225 if (!MI || !handledStoreType(MI))
226 continue;
227
228 // Found a store. Try to create a store group.
229 InstrGroup G;
230 createStoreGroup(BaseStore: MI, Begin: I+1, End: E, Group&: G);
231 if (G.size() > 1)
232 StoreGroups.push_back(x: G);
233 }
234}
235
236// Create a single store group. The stores need to be independent between
237// themselves, and also there cannot be other instructions between them
238// that could read or modify storage being stored into.
239void HexagonStoreWidening::createStoreGroup(MachineInstr *BaseStore,
240 InstrGroup::iterator Begin, InstrGroup::iterator End, InstrGroup &Group) {
241 assert(handledStoreType(BaseStore) && "Unexpected instruction");
242 unsigned BaseReg = getBaseAddressRegister(MI: BaseStore);
243 InstrGroup Other;
244
245 Group.push_back(x: BaseStore);
246
247 for (auto I = Begin; I != End; ++I) {
248 MachineInstr *MI = *I;
249 if (!MI)
250 continue;
251
252 if (handledStoreType(MI)) {
253 // If this store instruction is aliased with anything already in the
254 // group, terminate the group now.
255 if (instrAliased(Stores&: Group, MMO: getStoreTarget(MI)))
256 return;
257 // If this store is aliased to any of the memory instructions we have
258 // seen so far (that are not a part of this group), terminate the group.
259 if (instrAliased(Stores&: Other, MMO: getStoreTarget(MI)))
260 return;
261
262 unsigned BR = getBaseAddressRegister(MI);
263 if (BR == BaseReg) {
264 Group.push_back(x: MI);
265 *I = nullptr;
266 continue;
267 }
268 }
269
270 // Assume calls are aliased to everything.
271 if (MI->isCall() || MI->hasUnmodeledSideEffects())
272 return;
273
274 if (MI->mayLoadOrStore()) {
275 if (MI->hasOrderedMemoryRef() || instrAliased(Stores&: Group, MI))
276 return;
277 Other.push_back(x: MI);
278 }
279 } // for
280}
281
282// Check if store instructions S1 and S2 are adjacent. More precisely,
283// S2 has to access memory immediately following that accessed by S1.
284bool HexagonStoreWidening::storesAreAdjacent(const MachineInstr *S1,
285 const MachineInstr *S2) {
286 if (!handledStoreType(MI: S1) || !handledStoreType(MI: S2))
287 return false;
288
289 const MachineMemOperand &S1MO = getStoreTarget(MI: S1);
290
291 // Currently only handling immediate stores.
292 int Off1 = S1->getOperand(i: 1).getImm();
293 int Off2 = S2->getOperand(i: 1).getImm();
294
295 return (Off1 >= 0) ? Off1 + S1MO.getSize().getValue() == unsigned(Off2)
296 : int(Off1 + S1MO.getSize().getValue()) == Off2;
297}
298
299/// Given a sequence of adjacent stores, and a maximum size of a single wide
300/// store, pick a group of stores that can be replaced by a single store
301/// of size not exceeding MaxSize. The selected sequence will be recorded
302/// in OG ("old group" of instructions).
303/// OG should be empty on entry, and should be left empty if the function
304/// fails.
305bool HexagonStoreWidening::selectStores(InstrGroup::iterator Begin,
306 InstrGroup::iterator End, InstrGroup &OG, unsigned &TotalSize,
307 unsigned MaxSize) {
308 assert(Begin != End && "No instructions to analyze");
309 assert(OG.empty() && "Old group not empty on entry");
310
311 if (std::distance(first: Begin, last: End) <= 1)
312 return false;
313
314 MachineInstr *FirstMI = *Begin;
315 assert(!FirstMI->memoperands_empty() && "Expecting some memory operands");
316 const MachineMemOperand &FirstMMO = getStoreTarget(MI: FirstMI);
317 unsigned Alignment = FirstMMO.getAlign().value();
318 unsigned SizeAccum = FirstMMO.getSize().getValue();
319 unsigned FirstOffset = getStoreOffset(MI: FirstMI);
320
321 // The initial value of SizeAccum should always be a power of 2.
322 assert(isPowerOf2_32(SizeAccum) && "First store size not a power of 2");
323
324 // If the size of the first store equals to or exceeds the limit, do nothing.
325 if (SizeAccum >= MaxSize)
326 return false;
327
328 // If the size of the first store is greater than or equal to the address
329 // stored to, then the store cannot be made any wider.
330 if (SizeAccum >= Alignment)
331 return false;
332
333 // The offset of a store will put restrictions on how wide the store can be.
334 // Offsets in stores of size 2^n bytes need to have the n lowest bits be 0.
335 // If the first store already exhausts the offset limits, quit. Test this
336 // by checking if the next wider size would exceed the limit.
337 if ((2*SizeAccum-1) & FirstOffset)
338 return false;
339
340 OG.push_back(x: FirstMI);
341 MachineInstr *S1 = FirstMI;
342
343 // Pow2Num will be the largest number of elements in OG such that the sum
344 // of sizes of stores 0...Pow2Num-1 will be a power of 2.
345 unsigned Pow2Num = 1;
346 unsigned Pow2Size = SizeAccum;
347
348 // Be greedy: keep accumulating stores as long as they are to adjacent
349 // memory locations, and as long as the total number of bytes stored
350 // does not exceed the limit (MaxSize).
351 // Keep track of when the total size covered is a power of 2, since
352 // this is a size a single store can cover.
353 for (InstrGroup::iterator I = Begin + 1; I != End; ++I) {
354 MachineInstr *S2 = *I;
355 // Stores are sorted, so if S1 and S2 are not adjacent, there won't be
356 // any other store to fill the "hole".
357 if (!storesAreAdjacent(S1, S2))
358 break;
359
360 unsigned S2Size = getStoreTarget(MI: S2).getSize().getValue();
361 if (SizeAccum + S2Size > std::min(a: MaxSize, b: Alignment))
362 break;
363
364 OG.push_back(x: S2);
365 SizeAccum += S2Size;
366 if (isPowerOf2_32(Value: SizeAccum)) {
367 Pow2Num = OG.size();
368 Pow2Size = SizeAccum;
369 }
370 if ((2*Pow2Size-1) & FirstOffset)
371 break;
372
373 S1 = S2;
374 }
375
376 // The stores don't add up to anything that can be widened. Clean up.
377 if (Pow2Num <= 1) {
378 OG.clear();
379 return false;
380 }
381
382 // Only leave the stored being widened.
383 OG.resize(new_size: Pow2Num);
384 TotalSize = Pow2Size;
385 return true;
386}
387
388/// Given an "old group" OG of stores, create a "new group" NG of instructions
389/// to replace them. Ideally, NG would only have a single instruction in it,
390/// but that may only be possible for store-immediate.
391bool HexagonStoreWidening::createWideStores(InstrGroup &OG, InstrGroup &NG,
392 unsigned TotalSize) {
393 // XXX Current limitations:
394 // - only expect stores of immediate values in OG,
395 // - only handle a TotalSize of up to 4.
396
397 if (TotalSize > 4)
398 return false;
399
400 unsigned Acc = 0; // Value accumulator.
401 unsigned Shift = 0;
402
403 for (MachineInstr *MI : OG) {
404 const MachineMemOperand &MMO = getStoreTarget(MI);
405 MachineOperand &SO = MI->getOperand(i: 2); // Source.
406 assert(SO.isImm() && "Expecting an immediate operand");
407
408 unsigned NBits = MMO.getSize().getValue() * 8;
409 unsigned Mask = (0xFFFFFFFFU >> (32-NBits));
410 unsigned Val = (SO.getImm() & Mask) << Shift;
411 Acc |= Val;
412 Shift += NBits;
413 }
414
415 MachineInstr *FirstSt = OG.front();
416 DebugLoc DL = OG.back()->getDebugLoc();
417 const MachineMemOperand &OldM = getStoreTarget(MI: FirstSt);
418 MachineMemOperand *NewM =
419 MF->getMachineMemOperand(PtrInfo: OldM.getPointerInfo(), F: OldM.getFlags(),
420 Size: TotalSize, BaseAlignment: OldM.getAlign(), AAInfo: OldM.getAAInfo());
421
422 if (Acc < 0x10000) {
423 // Create mem[hw] = #Acc
424 unsigned WOpc = (TotalSize == 2) ? Hexagon::S4_storeirh_io :
425 (TotalSize == 4) ? Hexagon::S4_storeiri_io : 0;
426 assert(WOpc && "Unexpected size");
427
428 int Val = (TotalSize == 2) ? int16_t(Acc) : int(Acc);
429 const MCInstrDesc &StD = TII->get(Opcode: WOpc);
430 MachineOperand &MR = FirstSt->getOperand(i: 0);
431 int64_t Off = FirstSt->getOperand(i: 1).getImm();
432 MachineInstr *StI =
433 BuildMI(MF&: *MF, MIMD: DL, MCID: StD)
434 .addReg(RegNo: MR.getReg(), flags: getKillRegState(B: MR.isKill()), SubReg: MR.getSubReg())
435 .addImm(Val: Off)
436 .addImm(Val);
437 StI->addMemOperand(MF&: *MF, MO: NewM);
438 NG.push_back(x: StI);
439 } else {
440 // Create vreg = A2_tfrsi #Acc; mem[hw] = vreg
441 const MCInstrDesc &TfrD = TII->get(Opcode: Hexagon::A2_tfrsi);
442 const TargetRegisterClass *RC = TII->getRegClass(MCID: TfrD, OpNum: 0, TRI, MF: *MF);
443 Register VReg = MF->getRegInfo().createVirtualRegister(RegClass: RC);
444 MachineInstr *TfrI = BuildMI(MF&: *MF, MIMD: DL, MCID: TfrD, DestReg: VReg)
445 .addImm(Val: int(Acc));
446 NG.push_back(x: TfrI);
447
448 unsigned WOpc = (TotalSize == 2) ? Hexagon::S2_storerh_io :
449 (TotalSize == 4) ? Hexagon::S2_storeri_io : 0;
450 assert(WOpc && "Unexpected size");
451
452 const MCInstrDesc &StD = TII->get(Opcode: WOpc);
453 MachineOperand &MR = FirstSt->getOperand(i: 0);
454 int64_t Off = FirstSt->getOperand(i: 1).getImm();
455 MachineInstr *StI =
456 BuildMI(MF&: *MF, MIMD: DL, MCID: StD)
457 .addReg(RegNo: MR.getReg(), flags: getKillRegState(B: MR.isKill()), SubReg: MR.getSubReg())
458 .addImm(Val: Off)
459 .addReg(RegNo: VReg, flags: RegState::Kill);
460 StI->addMemOperand(MF&: *MF, MO: NewM);
461 NG.push_back(x: StI);
462 }
463
464 return true;
465}
466
467// Replace instructions from the old group OG with instructions from the
468// new group NG. Conceptually, remove all instructions in OG, and then
469// insert all instructions in NG, starting at where the first instruction
470// from OG was (in the order in which they appeared in the basic block).
471// (The ordering in OG does not have to match the order in the basic block.)
472bool HexagonStoreWidening::replaceStores(InstrGroup &OG, InstrGroup &NG) {
473 LLVM_DEBUG({
474 dbgs() << "Replacing:\n";
475 for (auto I : OG)
476 dbgs() << " " << *I;
477 dbgs() << "with\n";
478 for (auto I : NG)
479 dbgs() << " " << *I;
480 });
481
482 MachineBasicBlock *MBB = OG.back()->getParent();
483 MachineBasicBlock::iterator InsertAt = MBB->end();
484
485 // Need to establish the insertion point. The best one is right before
486 // the first store in the OG, but in the order in which the stores occur
487 // in the program list. Since the ordering in OG does not correspond
488 // to the order in the program list, we need to do some work to find
489 // the insertion point.
490
491 // Create a set of all instructions in OG (for quick lookup).
492 SmallPtrSet<MachineInstr*, 4> InstrSet;
493 for (auto *I : OG)
494 InstrSet.insert(Ptr: I);
495
496 // Traverse the block, until we hit an instruction from OG.
497 for (auto &I : *MBB) {
498 if (InstrSet.count(Ptr: &I)) {
499 InsertAt = I;
500 break;
501 }
502 }
503
504 assert((InsertAt != MBB->end()) && "Cannot locate any store from the group");
505
506 bool AtBBStart = false;
507
508 // InsertAt points at the first instruction that will be removed. We need
509 // to move it out of the way, so it remains valid after removing all the
510 // old stores, and so we are able to recover it back to the proper insertion
511 // position.
512 if (InsertAt != MBB->begin())
513 --InsertAt;
514 else
515 AtBBStart = true;
516
517 for (auto *I : OG)
518 I->eraseFromParent();
519
520 if (!AtBBStart)
521 ++InsertAt;
522 else
523 InsertAt = MBB->begin();
524
525 for (auto *I : NG)
526 MBB->insert(I: InsertAt, MI: I);
527
528 return true;
529}
530
531// Break up the group into smaller groups, each of which can be replaced by
532// a single wide store. Widen each such smaller group and replace the old
533// instructions with the widened ones.
534bool HexagonStoreWidening::processStoreGroup(InstrGroup &Group) {
535 bool Changed = false;
536 InstrGroup::iterator I = Group.begin(), E = Group.end();
537 InstrGroup OG, NG; // Old and new groups.
538 unsigned CollectedSize;
539
540 while (I != E) {
541 OG.clear();
542 NG.clear();
543
544 bool Succ = selectStores(Begin: I++, End: E, OG, TotalSize&: CollectedSize, MaxSize: MaxWideSize) &&
545 createWideStores(OG, NG, TotalSize: CollectedSize) &&
546 replaceStores(OG, NG);
547 if (!Succ)
548 continue;
549
550 assert(OG.size() > 1 && "Created invalid group");
551 assert(distance(I, E)+1 >= int(OG.size()) && "Too many elements");
552 I += OG.size()-1;
553
554 Changed = true;
555 }
556
557 return Changed;
558}
559
560// Process a single basic block: create the store groups, and replace them
561// with the widened stores, if possible. Processing of each basic block
562// is independent from processing of any other basic block. This transfor-
563// mation could be stopped after having processed any basic block without
564// any ill effects (other than not having performed widening in the unpro-
565// cessed blocks). Also, the basic blocks can be processed in any order.
566bool HexagonStoreWidening::processBasicBlock(MachineBasicBlock &MBB) {
567 InstrGroupList SGs;
568 bool Changed = false;
569
570 createStoreGroups(MBB, StoreGroups&: SGs);
571
572 auto Less = [] (const MachineInstr *A, const MachineInstr *B) -> bool {
573 return getStoreOffset(MI: A) < getStoreOffset(MI: B);
574 };
575 for (auto &G : SGs) {
576 assert(G.size() > 1 && "Store group with fewer than 2 elements");
577 llvm::sort(C&: G, Comp: Less);
578
579 Changed |= processStoreGroup(Group&: G);
580 }
581
582 return Changed;
583}
584
585bool HexagonStoreWidening::runOnMachineFunction(MachineFunction &MFn) {
586 if (skipFunction(F: MFn.getFunction()))
587 return false;
588
589 MF = &MFn;
590 auto &ST = MFn.getSubtarget<HexagonSubtarget>();
591 TII = ST.getInstrInfo();
592 TRI = ST.getRegisterInfo();
593 MRI = &MFn.getRegInfo();
594 AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
595
596 bool Changed = false;
597
598 for (auto &B : MFn)
599 Changed |= processBasicBlock(MBB&: B);
600
601 return Changed;
602}
603
604FunctionPass *llvm::createHexagonStoreWidening() {
605 return new HexagonStoreWidening();
606}
607