aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/llvm16/lib/CodeGen/LexicalScopes.cpp
blob: 47c19c3d8ec45054a7d0b49904811596339b6f08 (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
//===- LexicalScopes.cpp - Collecting lexical scope info ------------------===//
//
// 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 LexicalScopes analysis.
//
// This pass collects lexical scope information and maps machine instructions
// to respective lexical scopes.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/LexicalScopes.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Metadata.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <string>
#include <tuple>
#include <utility>

using namespace llvm;

#define DEBUG_TYPE "lexicalscopes"

/// reset - Reset the instance so that it's prepared for another function.
void LexicalScopes::reset() {
  MF = nullptr;
  CurrentFnLexicalScope = nullptr;
  LexicalScopeMap.clear();
  AbstractScopeMap.clear();
  InlinedLexicalScopeMap.clear();
  AbstractScopesList.clear();
  DominatedBlocks.clear();
}

/// initialize - Scan machine function and constuct lexical scope nest.
void LexicalScopes::initialize(const MachineFunction &Fn) {
  reset();
  // Don't attempt any lexical scope creation for a NoDebug compile unit.
  if (Fn.getFunction().getSubprogram()->getUnit()->getEmissionKind() ==
      DICompileUnit::NoDebug)
    return;
  MF = &Fn;
  SmallVector<InsnRange, 4> MIRanges;
  DenseMap<const MachineInstr *, LexicalScope *> MI2ScopeMap;
  extractLexicalScopes(MIRanges, MI2ScopeMap);
  if (CurrentFnLexicalScope) {
    constructScopeNest(CurrentFnLexicalScope);
    assignInstructionRanges(MIRanges, MI2ScopeMap);
  }
}

/// extractLexicalScopes - Extract instruction ranges for each lexical scopes
/// for the given machine function.
void LexicalScopes::extractLexicalScopes(
    SmallVectorImpl<InsnRange> &MIRanges,
    DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
  // Scan each instruction and create scopes. First build working set of scopes.
  for (const auto &MBB : *MF) {
    const MachineInstr *RangeBeginMI = nullptr;
    const MachineInstr *PrevMI = nullptr;
    const DILocation *PrevDL = nullptr;
    for (const auto &MInsn : MBB) {
      // Ignore DBG_VALUE and similar instruction that do not contribute to any
      // instruction in the output.
      if (MInsn.isMetaInstruction())
        continue;

      // Check if instruction has valid location information.
      const DILocation *MIDL = MInsn.getDebugLoc();
      if (!MIDL) {
        PrevMI = &MInsn;
        continue;
      }

      // If scope has not changed then skip this instruction.
      if (MIDL == PrevDL) {
        PrevMI = &MInsn;
        continue;
      }

      if (RangeBeginMI) {
        // If we have already seen a beginning of an instruction range and
        // current instruction scope does not match scope of first instruction
        // in this range then create a new instruction range.
        InsnRange R(RangeBeginMI, PrevMI);
        MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
        MIRanges.push_back(R);
      }

      // This is a beginning of a new instruction range.
      RangeBeginMI = &MInsn;

      // Reset previous markers.
      PrevMI = &MInsn;
      PrevDL = MIDL;
    }

    // Create last instruction range.
    if (RangeBeginMI && PrevMI && PrevDL) {
      InsnRange R(RangeBeginMI, PrevMI);
      MIRanges.push_back(R);
      MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
    }
  }
}

/// findLexicalScope - Find lexical scope, either regular or inlined, for the
/// given DebugLoc. Return NULL if not found.
LexicalScope *LexicalScopes::findLexicalScope(const DILocation *DL) {
  DILocalScope *Scope = DL->getScope();
  if (!Scope)
    return nullptr;

  // The scope that we were created with could have an extra file - which
  // isn't what we care about in this case.
  Scope = Scope->getNonLexicalBlockFileScope();

  if (auto *IA = DL->getInlinedAt()) {
    auto I = InlinedLexicalScopeMap.find(std::make_pair(Scope, IA));
    return I != InlinedLexicalScopeMap.end() ? &I->second : nullptr;
  }
  return findLexicalScope(Scope);
}

/// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
/// not available then create new lexical scope.
LexicalScope *LexicalScopes::getOrCreateLexicalScope(const DILocalScope *Scope,
                                                     const DILocation *IA) {
  if (IA) {
    // Skip scopes inlined from a NoDebug compile unit.
    if (Scope->getSubprogram()->getUnit()->getEmissionKind() ==
        DICompileUnit::NoDebug)
      return getOrCreateLexicalScope(IA);
    // Create an abstract scope for inlined function.
    getOrCreateAbstractScope(Scope);
    // Create an inlined scope for inlined function.
    return getOrCreateInlinedScope(Scope, IA);
  }

  return getOrCreateRegularScope(Scope);
}

/// getOrCreateRegularScope - Find or create a regular lexical scope.
LexicalScope *
LexicalScopes::getOrCreateRegularScope(const DILocalScope *Scope) {
  assert(Scope && "Invalid Scope encoding!");
  Scope = Scope->getNonLexicalBlockFileScope();

  auto I = LexicalScopeMap.find(Scope);
  if (I != LexicalScopeMap.end())
    return &I->second;

  // FIXME: Should the following dyn_cast be DILexicalBlock?
  LexicalScope *Parent = nullptr;
  if (auto *Block = dyn_cast<DILexicalBlockBase>(Scope))
    Parent = getOrCreateLexicalScope(Block->getScope());
  I = LexicalScopeMap.emplace(std::piecewise_construct,
                              std::forward_as_tuple(Scope),
                              std::forward_as_tuple(Parent, Scope, nullptr,
                                                    false)).first;

  if (!Parent) {
    assert(cast<DISubprogram>(Scope)->describes(&MF->getFunction()));
    assert(!CurrentFnLexicalScope);
    CurrentFnLexicalScope = &I->second;
  }

  return &I->second;
}

/// getOrCreateInlinedScope - Find or create an inlined lexical scope.
LexicalScope *
LexicalScopes::getOrCreateInlinedScope(const DILocalScope *Scope,
                                       const DILocation *InlinedAt) {
  assert(Scope && "Invalid Scope encoding!");
  Scope = Scope->getNonLexicalBlockFileScope();
  std::pair<const DILocalScope *, const DILocation *> P(Scope, InlinedAt);
  auto I = InlinedLexicalScopeMap.find(P);
  if (I != InlinedLexicalScopeMap.end())
    return &I->second;

  LexicalScope *Parent;
  if (auto *Block = dyn_cast<DILexicalBlockBase>(Scope))
    Parent = getOrCreateInlinedScope(Block->getScope(), InlinedAt);
  else
    Parent = getOrCreateLexicalScope(InlinedAt);

  I = InlinedLexicalScopeMap
          .emplace(std::piecewise_construct, std::forward_as_tuple(P),
                   std::forward_as_tuple(Parent, Scope, InlinedAt, false))
          .first;
  return &I->second;
}

/// getOrCreateAbstractScope - Find or create an abstract lexical scope.
LexicalScope *
LexicalScopes::getOrCreateAbstractScope(const DILocalScope *Scope) {
  assert(Scope && "Invalid Scope encoding!");
  Scope = Scope->getNonLexicalBlockFileScope();
  auto I = AbstractScopeMap.find(Scope);
  if (I != AbstractScopeMap.end())
    return &I->second;

  // FIXME: Should the following isa be DILexicalBlock?
  LexicalScope *Parent = nullptr;
  if (auto *Block = dyn_cast<DILexicalBlockBase>(Scope))
    Parent = getOrCreateAbstractScope(Block->getScope());

  I = AbstractScopeMap.emplace(std::piecewise_construct,
                               std::forward_as_tuple(Scope),
                               std::forward_as_tuple(Parent, Scope,
                                                     nullptr, true)).first;
  if (isa<DISubprogram>(Scope))
    AbstractScopesList.push_back(&I->second);
  return &I->second;
}

/// constructScopeNest - Traverse the Scope tree depth-first, storing
/// traversal state in WorkStack and recording the depth-first
/// numbering (setDFSIn, setDFSOut) for edge classification.
void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
  assert(Scope && "Unable to calculate scope dominance graph!");
  SmallVector<std::pair<LexicalScope *, size_t>, 4> WorkStack;
  WorkStack.push_back(std::make_pair(Scope, 0));
  unsigned Counter = 0;
  while (!WorkStack.empty()) {
    auto &ScopePosition = WorkStack.back();
    LexicalScope *WS = ScopePosition.first;
    size_t ChildNum = ScopePosition.second++;
    const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
    if (ChildNum < Children.size()) {
      auto &ChildScope = Children[ChildNum];
      WorkStack.push_back(std::make_pair(ChildScope, 0));
      ChildScope->setDFSIn(++Counter);
    } else {
      WorkStack.pop_back();
      WS->setDFSOut(++Counter);
    }
  }
}

/// assignInstructionRanges - Find ranges of instructions covered by each
/// lexical scope.
void LexicalScopes::assignInstructionRanges(
    SmallVectorImpl<InsnRange> &MIRanges,
    DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
  LexicalScope *PrevLexicalScope = nullptr;
  for (const auto &R : MIRanges) {
    LexicalScope *S = MI2ScopeMap.lookup(R.first);
    assert(S && "Lost LexicalScope for a machine instruction!");
    if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
      PrevLexicalScope->closeInsnRange(S);
    S->openInsnRange(R.first);
    S->extendInsnRange(R.second);
    PrevLexicalScope = S;
  }

  if (PrevLexicalScope)
    PrevLexicalScope->closeInsnRange();
}

/// getMachineBasicBlocks - Populate given set using machine basic blocks which
/// have machine instructions that belong to lexical scope identified by
/// DebugLoc.
void LexicalScopes::getMachineBasicBlocks(
    const DILocation *DL, SmallPtrSetImpl<const MachineBasicBlock *> &MBBs) {
  assert(MF && "Method called on a uninitialized LexicalScopes object!");
  MBBs.clear();

  LexicalScope *Scope = getOrCreateLexicalScope(DL);
  if (!Scope)
    return;

  if (Scope == CurrentFnLexicalScope) {
    for (const auto &MBB : *MF)
      MBBs.insert(&MBB);
    return;
  }

  // The scope ranges can cover multiple basic blocks in each span. Iterate over
  // all blocks (in the order they are in the function) until we reach the one
  // containing the end of the span.
  SmallVectorImpl<InsnRange> &InsnRanges = Scope->getRanges();
  for (auto &R : InsnRanges)
    for (auto CurMBBIt = R.first->getParent()->getIterator(),
              EndBBIt = std::next(R.second->getParent()->getIterator());
         CurMBBIt != EndBBIt; CurMBBIt++)
      MBBs.insert(&*CurMBBIt);
}

bool LexicalScopes::dominates(const DILocation *DL, MachineBasicBlock *MBB) {
  assert(MF && "Unexpected uninitialized LexicalScopes object!");
  LexicalScope *Scope = getOrCreateLexicalScope(DL);
  if (!Scope)
    return false;

  // Current function scope covers all basic blocks in the function.
  if (Scope == CurrentFnLexicalScope && MBB->getParent() == MF)
    return true;

  // Fetch all the blocks in DLs scope. Because the range / block list also
  // contain any subscopes, any instruction that DL dominates can be found in
  // the block set.
  //
  // Cache the set of fetched blocks to avoid repeatedly recomputing the set in
  // the LiveDebugValues pass.
  std::unique_ptr<BlockSetT> &Set = DominatedBlocks[DL];
  if (!Set) {
    Set = std::make_unique<BlockSetT>();
    getMachineBasicBlocks(DL, *Set);
  }
  return Set->contains(MBB);
}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void LexicalScope::dump(unsigned Indent) const {
  raw_ostream &err = dbgs();
  err.indent(Indent);
  err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
  const MDNode *N = Desc;
  err.indent(Indent);
  N->dump();
  if (AbstractScope)
    err << std::string(Indent, ' ') << "Abstract Scope\n";

  if (!Children.empty())
    err << std::string(Indent + 2, ' ') << "Children ...\n";
  for (unsigned i = 0, e = Children.size(); i != e; ++i)
    if (Children[i] != this)
      Children[i]->dump(Indent + 2);
}
#endif