aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/llvm14/utils/TableGen/DAGISelMatcherOpt.cpp
blob: 4273bd69b87d3d138b85ce1d0dbb138da4379aaa (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
//===- DAGISelMatcherOpt.cpp - Optimize a DAG Matcher ---------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the DAG Matcher optimizer.
//
//===----------------------------------------------------------------------===//

#include "DAGISelMatcher.h"
#include "CodeGenDAGPatterns.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;

#define DEBUG_TYPE "isel-opt"

/// ContractNodes - Turn multiple matcher node patterns like 'MoveChild+Record'
/// into single compound nodes like RecordChild.
static void ContractNodes(std::unique_ptr<Matcher> &MatcherPtr,
                          const CodeGenDAGPatterns &CGP) {
  // If we reached the end of the chain, we're done.
  Matcher *N = MatcherPtr.get();
  if (!N) return;
  
  // If we have a scope node, walk down all of the children.
  if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
    for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
      std::unique_ptr<Matcher> Child(Scope->takeChild(i));
      ContractNodes(Child, CGP);
      Scope->resetChild(i, Child.release());
    }
    return;
  }
  
  // If we found a movechild node with a node that comes in a 'foochild' form,
  // transform it.
  if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N)) {
    Matcher *New = nullptr;
    if (RecordMatcher *RM = dyn_cast<RecordMatcher>(MC->getNext()))
      if (MC->getChildNo() < 8)  // Only have RecordChild0...7
        New = new RecordChildMatcher(MC->getChildNo(), RM->getWhatFor(),
                                     RM->getResultNo());

    if (CheckTypeMatcher *CT = dyn_cast<CheckTypeMatcher>(MC->getNext()))
      if (MC->getChildNo() < 8 &&  // Only have CheckChildType0...7
          CT->getResNo() == 0)     // CheckChildType checks res #0
        New = new CheckChildTypeMatcher(MC->getChildNo(), CT->getType());

    if (CheckSameMatcher *CS = dyn_cast<CheckSameMatcher>(MC->getNext()))
      if (MC->getChildNo() < 4)  // Only have CheckChildSame0...3
        New = new CheckChildSameMatcher(MC->getChildNo(), CS->getMatchNumber());

    if (CheckIntegerMatcher *CI = dyn_cast<CheckIntegerMatcher>(MC->getNext()))
      if (MC->getChildNo() < 5)  // Only have CheckChildInteger0...4
        New = new CheckChildIntegerMatcher(MC->getChildNo(), CI->getValue());

    if (auto *CCC = dyn_cast<CheckCondCodeMatcher>(MC->getNext()))
      if (MC->getChildNo() == 2)  // Only have CheckChild2CondCode
        New = new CheckChild2CondCodeMatcher(CCC->getCondCodeName());

    if (New) {
      // Insert the new node.
      New->setNext(MatcherPtr.release());
      MatcherPtr.reset(New);
      // Remove the old one.
      MC->setNext(MC->getNext()->takeNext());
      return ContractNodes(MatcherPtr, CGP);
    }
  }
  
  // Zap movechild -> moveparent.
  if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N))
    if (MoveParentMatcher *MP = 
          dyn_cast<MoveParentMatcher>(MC->getNext())) {
      MatcherPtr.reset(MP->takeNext());
      return ContractNodes(MatcherPtr, CGP);
    }

  // Turn EmitNode->CompleteMatch into MorphNodeTo if we can.
  if (EmitNodeMatcher *EN = dyn_cast<EmitNodeMatcher>(N))
    if (CompleteMatchMatcher *CM =
          dyn_cast<CompleteMatchMatcher>(EN->getNext())) {
      // We can only use MorphNodeTo if the result values match up.
      unsigned RootResultFirst = EN->getFirstResultSlot();
      bool ResultsMatch = true;
      for (unsigned i = 0, e = CM->getNumResults(); i != e; ++i)
        if (CM->getResult(i) != RootResultFirst+i)
          ResultsMatch = false;
      
      // If the selected node defines a subset of the glue/chain results, we
      // can't use MorphNodeTo.  For example, we can't use MorphNodeTo if the
      // matched pattern has a chain but the root node doesn't.
      const PatternToMatch &Pattern = CM->getPattern();
      
      if (!EN->hasChain() &&
          Pattern.getSrcPattern()->NodeHasProperty(SDNPHasChain, CGP))
        ResultsMatch = false;

      // If the matched node has glue and the output root doesn't, we can't
      // use MorphNodeTo.
      //
      // NOTE: Strictly speaking, we don't have to check for glue here
      // because the code in the pattern generator doesn't handle it right.  We
      // do it anyway for thoroughness.
      if (!EN->hasOutFlag() &&
          Pattern.getSrcPattern()->NodeHasProperty(SDNPOutGlue, CGP))
        ResultsMatch = false;
      
      
      // If the root result node defines more results than the source root node
      // *and* has a chain or glue input, then we can't match it because it
      // would end up replacing the extra result with the chain/glue.
#if 0
      if ((EN->hasGlue() || EN->hasChain()) &&
          EN->getNumNonChainGlueVTs() > ... need to get no results reliably ...)
        ResultMatch = false;
#endif
          
      if (ResultsMatch) {
        const SmallVectorImpl<MVT::SimpleValueType> &VTs = EN->getVTList();
        const SmallVectorImpl<unsigned> &Operands = EN->getOperandList();
        MatcherPtr.reset(new MorphNodeToMatcher(EN->getOpcodeName(),
                                                VTs, Operands,
                                                EN->hasChain(), EN->hasInFlag(),
                                                EN->hasOutFlag(),
                                                EN->hasMemRefs(),
                                                EN->getNumFixedArityOperands(),
                                                Pattern));
        return;
      }

      // FIXME2: Kill off all the SelectionDAG::SelectNodeTo and getMachineNode
      // variants.
    }
  
  ContractNodes(N->getNextPtr(), CGP);
  
  
  // If we have a CheckType/CheckChildType/Record node followed by a
  // CheckOpcode, invert the two nodes.  We prefer to do structural checks
  // before type checks, as this opens opportunities for factoring on targets
  // like X86 where many operations are valid on multiple types.
  if ((isa<CheckTypeMatcher>(N) || isa<CheckChildTypeMatcher>(N) ||
       isa<RecordMatcher>(N)) &&
      isa<CheckOpcodeMatcher>(N->getNext())) {
    // Unlink the two nodes from the list.
    Matcher *CheckType = MatcherPtr.release();
    Matcher *CheckOpcode = CheckType->takeNext();
    Matcher *Tail = CheckOpcode->takeNext();
    
    // Relink them.
    MatcherPtr.reset(CheckOpcode);
    CheckOpcode->setNext(CheckType);
    CheckType->setNext(Tail);
    return ContractNodes(MatcherPtr, CGP);
  }
}

/// FindNodeWithKind - Scan a series of matchers looking for a matcher with a
/// specified kind.  Return null if we didn't find one otherwise return the
/// matcher.
static Matcher *FindNodeWithKind(Matcher *M, Matcher::KindTy Kind) {
  for (; M; M = M->getNext())
    if (M->getKind() == Kind)
      return M;
  return nullptr;
}


/// FactorNodes - Turn matches like this:
///   Scope
///     OPC_CheckType i32
///       ABC
///     OPC_CheckType i32
///       XYZ
/// into:
///   OPC_CheckType i32
///     Scope
///       ABC
///       XYZ
///
static void FactorNodes(std::unique_ptr<Matcher> &InputMatcherPtr) {
  // Look for a push node. Iterates instead of recurses to reduce stack usage.
  ScopeMatcher *Scope = nullptr;
  std::unique_ptr<Matcher> *RebindableMatcherPtr = &InputMatcherPtr;
  while (!Scope) {
    // If we reached the end of the chain, we're done.
    Matcher *N = RebindableMatcherPtr->get();
    if (!N) return;

    // If this is not a push node, just scan for one.
    Scope = dyn_cast<ScopeMatcher>(N);
    if (!Scope)
      RebindableMatcherPtr = &(N->getNextPtr());
  }
  std::unique_ptr<Matcher> &MatcherPtr = *RebindableMatcherPtr;
  
  // Okay, pull together the children of the scope node into a vector so we can
  // inspect it more easily.
  SmallVector<Matcher*, 32> OptionsToMatch;
  
  for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
    // Factor the subexpression.
    std::unique_ptr<Matcher> Child(Scope->takeChild(i));
    FactorNodes(Child);
    
    if (Child) {
      // If the child is a ScopeMatcher we can just merge its contents.
      if (auto *SM = dyn_cast<ScopeMatcher>(Child.get())) {
        for (unsigned j = 0, e = SM->getNumChildren(); j != e; ++j)
          OptionsToMatch.push_back(SM->takeChild(j));
      } else {
        OptionsToMatch.push_back(Child.release());
      }
    }
  }
  
  SmallVector<Matcher*, 32> NewOptionsToMatch;
  
  // Loop over options to match, merging neighboring patterns with identical
  // starting nodes into a shared matcher.
  for (unsigned OptionIdx = 0, e = OptionsToMatch.size(); OptionIdx != e;) {
    // Find the set of matchers that start with this node.
    Matcher *Optn = OptionsToMatch[OptionIdx++];

    if (OptionIdx == e) {
      NewOptionsToMatch.push_back(Optn);
      continue;
    }
    
    // See if the next option starts with the same matcher.  If the two
    // neighbors *do* start with the same matcher, we can factor the matcher out
    // of at least these two patterns.  See what the maximal set we can merge
    // together is.
    SmallVector<Matcher*, 8> EqualMatchers;
    EqualMatchers.push_back(Optn);
    
    // Factor all of the known-equal matchers after this one into the same
    // group.
    while (OptionIdx != e && OptionsToMatch[OptionIdx]->isEqual(Optn))
      EqualMatchers.push_back(OptionsToMatch[OptionIdx++]);

    // If we found a non-equal matcher, see if it is contradictory with the
    // current node.  If so, we know that the ordering relation between the
    // current sets of nodes and this node don't matter.  Look past it to see if
    // we can merge anything else into this matching group.
    unsigned Scan = OptionIdx;
    while (true) {
      // If we ran out of stuff to scan, we're done.
      if (Scan == e) break;
      
      Matcher *ScanMatcher = OptionsToMatch[Scan];
      
      // If we found an entry that matches out matcher, merge it into the set to
      // handle.
      if (Optn->isEqual(ScanMatcher)) {
        // If is equal after all, add the option to EqualMatchers and remove it
        // from OptionsToMatch.
        EqualMatchers.push_back(ScanMatcher);
        OptionsToMatch.erase(OptionsToMatch.begin()+Scan);
        --e;
        continue;
      }
      
      // If the option we're checking for contradicts the start of the list,
      // skip over it.
      if (Optn->isContradictory(ScanMatcher)) {
        ++Scan;
        continue;
      }

      // If we're scanning for a simple node, see if it occurs later in the
      // sequence.  If so, and if we can move it up, it might be contradictory
      // or the same as what we're looking for.  If so, reorder it.
      if (Optn->isSimplePredicateOrRecordNode()) {
        Matcher *M2 = FindNodeWithKind(ScanMatcher, Optn->getKind());
        if (M2 && M2 != ScanMatcher &&
            M2->canMoveBefore(ScanMatcher) &&
            (M2->isEqual(Optn) || M2->isContradictory(Optn))) {
          Matcher *MatcherWithoutM2 = ScanMatcher->unlinkNode(M2);
          M2->setNext(MatcherWithoutM2);
          OptionsToMatch[Scan] = M2;
          continue;
        }
      }
      
      // Otherwise, we don't know how to handle this entry, we have to bail.
      break;
    }
      
    if (Scan != e &&
        // Don't print it's obvious nothing extra could be merged anyway.
        Scan+1 != e) {
      LLVM_DEBUG(errs() << "Couldn't merge this:\n"; Optn->print(errs(), 4);
                 errs() << "into this:\n";
                 OptionsToMatch[Scan]->print(errs(), 4);
                 if (Scan + 1 != e) OptionsToMatch[Scan + 1]->printOne(errs());
                 if (Scan + 2 < e) OptionsToMatch[Scan + 2]->printOne(errs());
                 errs() << "\n");
    }
    
    // If we only found one option starting with this matcher, no factoring is
    // possible.
    if (EqualMatchers.size() == 1) {
      NewOptionsToMatch.push_back(EqualMatchers[0]);
      continue;
    }
    
    // Factor these checks by pulling the first node off each entry and
    // discarding it.  Take the first one off the first entry to reuse.
    Matcher *Shared = Optn;
    Optn = Optn->takeNext();
    EqualMatchers[0] = Optn;

    // Remove and delete the first node from the other matchers we're factoring.
    for (unsigned i = 1, e = EqualMatchers.size(); i != e; ++i) {
      Matcher *Tmp = EqualMatchers[i]->takeNext();
      delete EqualMatchers[i];
      EqualMatchers[i] = Tmp;
    }
    
    Shared->setNext(new ScopeMatcher(EqualMatchers));

    // Recursively factor the newly created node.
    FactorNodes(Shared->getNextPtr());
    
    NewOptionsToMatch.push_back(Shared);
  }
  
  // If we're down to a single pattern to match, then we don't need this scope
  // anymore.
  if (NewOptionsToMatch.size() == 1) {
    MatcherPtr.reset(NewOptionsToMatch[0]);
    return;
  }
  
  if (NewOptionsToMatch.empty()) {
    MatcherPtr.reset();
    return;
  }
  
  // If our factoring failed (didn't achieve anything) see if we can simplify in
  // other ways.
  
  // Check to see if all of the leading entries are now opcode checks.  If so,
  // we can convert this Scope to be a OpcodeSwitch instead.
  bool AllOpcodeChecks = true, AllTypeChecks = true;
  for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
    // Check to see if this breaks a series of CheckOpcodeMatchers.
    if (AllOpcodeChecks &&
        !isa<CheckOpcodeMatcher>(NewOptionsToMatch[i])) {
#if 0
      if (i > 3) {
        errs() << "FAILING OPC #" << i << "\n";
        NewOptionsToMatch[i]->dump();
      }
#endif
      AllOpcodeChecks = false;
    }

    // Check to see if this breaks a series of CheckTypeMatcher's.
    if (AllTypeChecks) {
      CheckTypeMatcher *CTM =
        cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
                                                        Matcher::CheckType));
      if (!CTM ||
          // iPTR checks could alias any other case without us knowing, don't
          // bother with them.
          CTM->getType() == MVT::iPTR ||
          // SwitchType only works for result #0.
          CTM->getResNo() != 0 ||
          // If the CheckType isn't at the start of the list, see if we can move
          // it there.
          !CTM->canMoveBefore(NewOptionsToMatch[i])) {
#if 0
        if (i > 3 && AllTypeChecks) {
          errs() << "FAILING TYPE #" << i << "\n";
          NewOptionsToMatch[i]->dump();
        }
#endif
        AllTypeChecks = false;
      }
    }
  }
  
  // If all the options are CheckOpcode's, we can form the SwitchOpcode, woot.
  if (AllOpcodeChecks) {
    StringSet<> Opcodes;
    SmallVector<std::pair<const SDNodeInfo*, Matcher*>, 8> Cases;
    for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
      CheckOpcodeMatcher *COM = cast<CheckOpcodeMatcher>(NewOptionsToMatch[i]);
      assert(Opcodes.insert(COM->getOpcode().getEnumName()).second &&
             "Duplicate opcodes not factored?");
      Cases.push_back(std::make_pair(&COM->getOpcode(), COM->takeNext()));
      delete COM;
    }
    
    MatcherPtr.reset(new SwitchOpcodeMatcher(Cases));
    return;
  }
  
  // If all the options are CheckType's, we can form the SwitchType, woot.
  if (AllTypeChecks) {
    DenseMap<unsigned, unsigned> TypeEntry;
    SmallVector<std::pair<MVT::SimpleValueType, Matcher*>, 8> Cases;
    for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
      Matcher* M = FindNodeWithKind(NewOptionsToMatch[i], Matcher::CheckType);
      assert(M && isa<CheckTypeMatcher>(M) && "Unknown Matcher type");

      auto *CTM = cast<CheckTypeMatcher>(M);
      Matcher *MatcherWithoutCTM = NewOptionsToMatch[i]->unlinkNode(CTM);
      MVT::SimpleValueType CTMTy = CTM->getType();
      delete CTM;

      unsigned &Entry = TypeEntry[CTMTy];
      if (Entry != 0) {
        // If we have unfactored duplicate types, then we should factor them.
        Matcher *PrevMatcher = Cases[Entry-1].second;
        if (ScopeMatcher *SM = dyn_cast<ScopeMatcher>(PrevMatcher)) {
          SM->setNumChildren(SM->getNumChildren()+1);
          SM->resetChild(SM->getNumChildren()-1, MatcherWithoutCTM);
          continue;
        }
        
        Matcher *Entries[2] = { PrevMatcher, MatcherWithoutCTM };
        Cases[Entry-1].second = new ScopeMatcher(Entries);
        continue;
      }
      
      Entry = Cases.size()+1;
      Cases.push_back(std::make_pair(CTMTy, MatcherWithoutCTM));
    }
    
    // Make sure we recursively factor any scopes we may have created.
    for (auto &M : Cases) {
      if (ScopeMatcher *SM = dyn_cast<ScopeMatcher>(M.second)) {
        std::unique_ptr<Matcher> Scope(SM);
        FactorNodes(Scope);
        M.second = Scope.release();
        assert(M.second && "null matcher");
      }
    }

    if (Cases.size() != 1) {
      MatcherPtr.reset(new SwitchTypeMatcher(Cases));
    } else {
      // If we factored and ended up with one case, create it now.
      MatcherPtr.reset(new CheckTypeMatcher(Cases[0].first, 0));
      MatcherPtr->setNext(Cases[0].second);
    }
    return;
  }
  

  // Reassemble the Scope node with the adjusted children.
  Scope->setNumChildren(NewOptionsToMatch.size());
  for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i)
    Scope->resetChild(i, NewOptionsToMatch[i]);
}

void
llvm::OptimizeMatcher(std::unique_ptr<Matcher> &MatcherPtr,
                      const CodeGenDAGPatterns &CGP) {
  ContractNodes(MatcherPtr, CGP);
  FactorNodes(MatcherPtr);
}