aboutsummaryrefslogtreecommitdiff
path: root/clang/lib/AST/ByteCode/EvalEmitter.cpp
blob: 81ebc5694d6f002bbed0cbb6088c902350699ced (plain)
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
//===--- EvalEmitter.cpp - Instruction emitter for the VM -------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//

#include "EvalEmitter.h"
#include "Context.h"
#include "IntegralAP.h"
#include "Interp.h"
#include "clang/AST/DeclCXX.h"

using namespace clang;
using namespace clang::interp;

EvalEmitter::EvalEmitter(Context &Ctx, Program &P, State &Parent,
                         InterpStack &Stk)
    : Ctx(Ctx), P(P), S(Parent, P, Stk, Ctx, this), EvalResult(&Ctx) {}

EvalEmitter::~EvalEmitter() {
  for (auto &V : Locals) {
    Block *B = reinterpret_cast<Block *>(V.get());
    if (B->isInitialized())
      B->invokeDtor();
  }
}

/// Clean up all our resources. This needs to done in failed evaluations before
/// we call InterpStack::clear(), because there might be a Pointer on the stack
/// pointing into a Block in the EvalEmitter.
void EvalEmitter::cleanup() { S.cleanup(); }

EvaluationResult EvalEmitter::interpretExpr(const Expr *E,
                                            bool ConvertResultToRValue,
                                            bool DestroyToplevelScope) {
  S.setEvalLocation(E->getExprLoc());
  this->ConvertResultToRValue = ConvertResultToRValue && !isa<ConstantExpr>(E);
  this->CheckFullyInitialized = isa<ConstantExpr>(E);
  EvalResult.setSource(E);

  if (!this->visitExpr(E, DestroyToplevelScope)) {
    // EvalResult may already have a result set, but something failed
    // after that (e.g. evaluating destructors).
    EvalResult.setInvalid();
  }

  return std::move(this->EvalResult);
}

EvaluationResult EvalEmitter::interpretDecl(const VarDecl *VD,
                                            bool CheckFullyInitialized) {
  this->CheckFullyInitialized = CheckFullyInitialized;
  S.EvaluatingDecl = VD;
  EvalResult.setSource(VD);

  if (const Expr *Init = VD->getAnyInitializer()) {
    QualType T = VD->getType();
    this->ConvertResultToRValue = !Init->isGLValue() && !T->isPointerType() &&
                                  !T->isObjCObjectPointerType();
  } else
    this->ConvertResultToRValue = false;

  EvalResult.setSource(VD);

  if (!this->visitDeclAndReturn(VD, S.inConstantContext()))
    EvalResult.setInvalid();

  S.EvaluatingDecl = nullptr;
  updateGlobalTemporaries();
  return std::move(this->EvalResult);
}

EvaluationResult EvalEmitter::interpretAsPointer(const Expr *E,
                                                 PtrCallback PtrCB) {

  S.setEvalLocation(E->getExprLoc());
  this->ConvertResultToRValue = false;
  this->CheckFullyInitialized = false;
  this->PtrCB = PtrCB;
  EvalResult.setSource(E);

  if (!this->visitExpr(E, /*DestroyToplevelScope=*/true)) {
    // EvalResult may already have a result set, but something failed
    // after that (e.g. evaluating destructors).
    EvalResult.setInvalid();
  }

  return std::move(this->EvalResult);
}

bool EvalEmitter::interpretCall(const FunctionDecl *FD, const Expr *E) {
  // Add parameters to the parameter map. The values in the ParamOffset don't
  // matter in this case as reading from them can't ever work.
  for (const ParmVarDecl *PD : FD->parameters()) {
    this->Params.insert({PD, {0, false}});
  }

  if (!this->visit(E))
    return false;
  PrimType T = Ctx.classify(E).value_or(PT_Ptr);
  return this->emitPop(T, E);
}

void EvalEmitter::emitLabel(LabelTy Label) { CurrentLabel = Label; }

EvalEmitter::LabelTy EvalEmitter::getLabel() { return NextLabel++; }

Scope::Local EvalEmitter::createLocal(Descriptor *D) {
  // Allocate memory for a local.
  auto Memory = std::make_unique<char[]>(sizeof(Block) + D->getAllocSize());
  auto *B = new (Memory.get()) Block(Ctx.getEvalID(), D, /*isStatic=*/false);
  B->invokeCtor();

  // Initialize local variable inline descriptor.
  InlineDescriptor &Desc = *reinterpret_cast<InlineDescriptor *>(B->rawData());
  Desc.Desc = D;
  Desc.Offset = sizeof(InlineDescriptor);
  Desc.IsActive = true;
  Desc.IsBase = false;
  Desc.IsFieldMutable = false;
  Desc.IsConst = false;
  Desc.IsInitialized = false;

  // Register the local.
  unsigned Off = Locals.size();
  Locals.push_back(std::move(Memory));
  return {Off, D};
}

bool EvalEmitter::jumpTrue(const LabelTy &Label) {
  if (isActive()) {
    if (S.Stk.pop<bool>())
      ActiveLabel = Label;
  }
  return true;
}

bool EvalEmitter::jumpFalse(const LabelTy &Label) {
  if (isActive()) {
    if (!S.Stk.pop<bool>())
      ActiveLabel = Label;
  }
  return true;
}

bool EvalEmitter::jump(const LabelTy &Label) {
  if (isActive())
    CurrentLabel = ActiveLabel = Label;
  return true;
}

bool EvalEmitter::fallthrough(const LabelTy &Label) {
  if (isActive())
    ActiveLabel = Label;
  CurrentLabel = Label;
  return true;
}

bool EvalEmitter::speculate(const CallExpr *E, const LabelTy &EndLabel) {
  size_t StackSizeBefore = S.Stk.size();
  const Expr *Arg = E->getArg(0);
  if (!this->visit(Arg)) {
    S.Stk.clearTo(StackSizeBefore);

    if (S.inConstantContext() || Arg->HasSideEffects(S.getASTContext()))
      return this->emitBool(false, E);
    return Invalid(S, OpPC);
  }

  PrimType T = Ctx.classify(Arg->getType()).value_or(PT_Ptr);
  if (T == PT_Ptr) {
    const auto &Ptr = S.Stk.pop<Pointer>();
    return this->emitBool(CheckBCPResult(S, Ptr), E);
  }

  // Otherwise, this is fine!
  if (!this->emitPop(T, E))
    return false;
  return this->emitBool(true, E);
}

template <PrimType OpType> bool EvalEmitter::emitRet(const SourceInfo &Info) {
  if (!isActive())
    return true;

  using T = typename PrimConv<OpType>::T;
  EvalResult.setValue(S.Stk.pop<T>().toAPValue(Ctx.getASTContext()));
  return true;
}

template <> bool EvalEmitter::emitRet<PT_Ptr>(const SourceInfo &Info) {
  if (!isActive())
    return true;

  const Pointer &Ptr = S.Stk.pop<Pointer>();

  if (Ptr.isFunctionPointer()) {
    EvalResult.setValue(Ptr.toAPValue(Ctx.getASTContext()));
    return true;
  }

  // If we're returning a raw pointer, call our callback.
  if (this->PtrCB)
    return (*this->PtrCB)(Ptr);

  if (!EvalResult.checkReturnValue(S, Ctx, Ptr, Info))
    return false;
  if (CheckFullyInitialized && !EvalResult.checkFullyInitialized(S, Ptr))
    return false;

  // Implicitly convert lvalue to rvalue, if requested.
  if (ConvertResultToRValue) {
    if (!Ptr.isZero() && !Ptr.isDereferencable())
      return false;

    if (S.getLangOpts().CPlusPlus11 && Ptr.isBlockPointer() &&
        !CheckFinalLoad(S, OpPC, Ptr)) {
      return false;
    }

    // Never allow reading from a non-const pointer, unless the memory
    // has been created in this evaluation.
    if (!Ptr.isZero() && !Ptr.isConst() && Ptr.isBlockPointer() &&
        Ptr.block()->getEvalID() != Ctx.getEvalID())
      return false;

    if (std::optional<APValue> V =
            Ptr.toRValue(Ctx, EvalResult.getSourceType())) {
      EvalResult.setValue(*V);
    } else {
      return false;
    }
  } else {
    if (!Ptr.isLive() && !Ptr.isTemporary())
      return false;

    EvalResult.setValue(Ptr.toAPValue(Ctx.getASTContext()));
  }

  return true;
}

bool EvalEmitter::emitRetVoid(const SourceInfo &Info) {
  EvalResult.setValid();
  return true;
}

bool EvalEmitter::emitRetValue(const SourceInfo &Info) {
  const auto &Ptr = S.Stk.pop<Pointer>();

  if (!EvalResult.checkReturnValue(S, Ctx, Ptr, Info))
    return false;
  if (CheckFullyInitialized && !EvalResult.checkFullyInitialized(S, Ptr))
    return false;

  if (std::optional<APValue> APV =
          Ptr.toRValue(S.getASTContext(), EvalResult.getSourceType())) {
    EvalResult.setValue(*APV);
    return true;
  }

  EvalResult.setInvalid();
  return false;
}

bool EvalEmitter::emitGetPtrLocal(uint32_t I, const SourceInfo &Info) {
  if (!isActive())
    return true;

  Block *B = getLocal(I);
  S.Stk.push<Pointer>(B, sizeof(InlineDescriptor));
  return true;
}

template <PrimType OpType>
bool EvalEmitter::emitGetLocal(uint32_t I, const SourceInfo &Info) {
  if (!isActive())
    return true;

  using T = typename PrimConv<OpType>::T;

  Block *B = getLocal(I);
  S.Stk.push<T>(*reinterpret_cast<T *>(B->data()));
  return true;
}

template <PrimType OpType>
bool EvalEmitter::emitSetLocal(uint32_t I, const SourceInfo &Info) {
  if (!isActive())
    return true;

  using T = typename PrimConv<OpType>::T;

  Block *B = getLocal(I);
  *reinterpret_cast<T *>(B->data()) = S.Stk.pop<T>();
  InlineDescriptor &Desc = *reinterpret_cast<InlineDescriptor *>(B->rawData());
  Desc.IsInitialized = true;

  return true;
}

bool EvalEmitter::emitDestroy(uint32_t I, const SourceInfo &Info) {
  if (!isActive())
    return true;

  for (auto &Local : Descriptors[I]) {
    Block *B = getLocal(Local.Offset);
    S.deallocate(B);
  }

  return true;
}

/// Global temporaries (LifetimeExtendedTemporary) carry their value
/// around as an APValue, which codegen accesses.
/// We set their value once when creating them, but we don't update it
/// afterwards when code changes it later.
/// This is what we do here.
void EvalEmitter::updateGlobalTemporaries() {
  for (const auto &[E, Temp] : S.SeenGlobalTemporaries) {
    if (std::optional<unsigned> GlobalIndex = P.getGlobal(E)) {
      const Pointer &Ptr = P.getPtrGlobal(*GlobalIndex);
      APValue *Cached = Temp->getOrCreateValue(true);

      if (OptPrimType T = Ctx.classify(E->getType())) {
        TYPE_SWITCH(
            *T, { *Cached = Ptr.deref<T>().toAPValue(Ctx.getASTContext()); });
      } else {
        if (std::optional<APValue> APV =
                Ptr.toRValue(Ctx, Temp->getTemporaryExpr()->getType()))
          *Cached = *APV;
      }
    }
  }
  S.SeenGlobalTemporaries.clear();
}

//===----------------------------------------------------------------------===//
// Opcode evaluators
//===----------------------------------------------------------------------===//

#define GET_EVAL_IMPL
#include "Opcodes.inc"
#undef GET_EVAL_IMPL