1//===--- EvalEmitter.cpp - Instruction emitter for the VM -------*- C++ -*-===//
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#include "EvalEmitter.h"
10#include "Context.h"
11#include "IntegralAP.h"
12#include "Interp.h"
13#include "Opcode.h"
14#include "clang/AST/DeclCXX.h"
15
16using namespace clang;
17using namespace clang::interp;
18
19EvalEmitter::EvalEmitter(Context &Ctx, Program &P, State &Parent,
20 InterpStack &Stk)
21 : Ctx(Ctx), P(P), S(Parent, P, Stk, Ctx, this), EvalResult(&Ctx) {
22 // Create a dummy frame for the interpreter which does not have locals.
23 S.Current =
24 new InterpFrame(S, /*Func=*/nullptr, /*Caller=*/nullptr, CodePtr(), 0);
25}
26
27EvalEmitter::~EvalEmitter() {
28 for (auto &[K, V] : Locals) {
29 Block *B = reinterpret_cast<Block *>(V.get());
30 if (B->isInitialized())
31 B->invokeDtor();
32 }
33}
34
35/// Clean up all our resources. This needs to done in failed evaluations before
36/// we call InterpStack::clear(), because there might be a Pointer on the stack
37/// pointing into a Block in the EvalEmitter.
38void EvalEmitter::cleanup() { S.cleanup(); }
39
40EvaluationResult EvalEmitter::interpretExpr(const Expr *E,
41 bool ConvertResultToRValue) {
42 S.setEvalLocation(E->getExprLoc());
43 this->ConvertResultToRValue = ConvertResultToRValue && !isa<ConstantExpr>(Val: E);
44 this->CheckFullyInitialized = isa<ConstantExpr>(Val: E);
45 EvalResult.setSource(E);
46
47 if (!this->visitExpr(E)) {
48 // EvalResult may already have a result set, but something failed
49 // after that (e.g. evaluating destructors).
50 EvalResult.setInvalid();
51 }
52
53 return std::move(this->EvalResult);
54}
55
56EvaluationResult EvalEmitter::interpretDecl(const VarDecl *VD,
57 bool CheckFullyInitialized) {
58 this->CheckFullyInitialized = CheckFullyInitialized;
59 S.EvaluatingDecl = VD;
60 EvalResult.setSource(VD);
61
62 if (const Expr *Init = VD->getAnyInitializer()) {
63 QualType T = VD->getType();
64 this->ConvertResultToRValue = !Init->isGLValue() && !T->isPointerType() &&
65 !T->isObjCObjectPointerType();
66 } else
67 this->ConvertResultToRValue = false;
68
69 EvalResult.setSource(VD);
70
71 if (!this->visitDeclAndReturn(VD, ConstantContext: S.inConstantContext()))
72 EvalResult.setInvalid();
73
74 S.EvaluatingDecl = nullptr;
75 updateGlobalTemporaries();
76 return std::move(this->EvalResult);
77}
78
79void EvalEmitter::emitLabel(LabelTy Label) {
80 CurrentLabel = Label;
81}
82
83EvalEmitter::LabelTy EvalEmitter::getLabel() { return NextLabel++; }
84
85Scope::Local EvalEmitter::createLocal(Descriptor *D) {
86 // Allocate memory for a local.
87 auto Memory = std::make_unique<char[]>(num: sizeof(Block) + D->getAllocSize());
88 auto *B = new (Memory.get()) Block(Ctx.getEvalID(), D, /*isStatic=*/false);
89 B->invokeCtor();
90
91 // Initialize local variable inline descriptor.
92 InlineDescriptor &Desc = *reinterpret_cast<InlineDescriptor *>(B->rawData());
93 Desc.Desc = D;
94 Desc.Offset = sizeof(InlineDescriptor);
95 Desc.IsActive = true;
96 Desc.IsBase = false;
97 Desc.IsFieldMutable = false;
98 Desc.IsConst = false;
99 Desc.IsInitialized = false;
100
101 // Register the local.
102 unsigned Off = Locals.size();
103 Locals.insert(KV: {Off, std::move(Memory)});
104 return {.Offset: Off, .Desc: D};
105}
106
107bool EvalEmitter::jumpTrue(const LabelTy &Label) {
108 if (isActive()) {
109 if (S.Stk.pop<bool>())
110 ActiveLabel = Label;
111 }
112 return true;
113}
114
115bool EvalEmitter::jumpFalse(const LabelTy &Label) {
116 if (isActive()) {
117 if (!S.Stk.pop<bool>())
118 ActiveLabel = Label;
119 }
120 return true;
121}
122
123bool EvalEmitter::jump(const LabelTy &Label) {
124 if (isActive())
125 CurrentLabel = ActiveLabel = Label;
126 return true;
127}
128
129bool EvalEmitter::fallthrough(const LabelTy &Label) {
130 if (isActive())
131 ActiveLabel = Label;
132 CurrentLabel = Label;
133 return true;
134}
135
136static bool checkReturnState(InterpState &S) {
137 return S.maybeDiagnoseDanglingAllocations();
138}
139
140template <PrimType OpType> bool EvalEmitter::emitRet(const SourceInfo &Info) {
141 if (!isActive())
142 return true;
143
144 if (!checkReturnState(S))
145 return false;
146
147 using T = typename PrimConv<OpType>::T;
148 EvalResult.setValue(S.Stk.pop<T>().toAPValue(Ctx.getASTContext()));
149 return true;
150}
151
152template <> bool EvalEmitter::emitRet<PT_Ptr>(const SourceInfo &Info) {
153 if (!isActive())
154 return true;
155
156 const Pointer &Ptr = S.Stk.pop<Pointer>();
157
158 if (!EvalResult.checkReturnValue(S, Ctx, Ptr, Info))
159 return false;
160 if (CheckFullyInitialized && !EvalResult.checkFullyInitialized(S, Ptr))
161 return false;
162
163 if (!checkReturnState(S))
164 return false;
165
166 // Implicitly convert lvalue to rvalue, if requested.
167 if (ConvertResultToRValue) {
168 if (!Ptr.isZero() && !Ptr.isDereferencable())
169 return false;
170 // Never allow reading from a non-const pointer, unless the memory
171 // has been created in this evaluation.
172 if (!Ptr.isZero() && Ptr.isBlockPointer() &&
173 Ptr.block()->getEvalID() != Ctx.getEvalID() &&
174 (!CheckLoad(S, OpPC, Ptr, AK: AK_Read) || !Ptr.isConst()))
175 return false;
176
177 if (std::optional<APValue> V =
178 Ptr.toRValue(Ctx, ResultType: EvalResult.getSourceType())) {
179 EvalResult.setValue(*V);
180 } else {
181 return false;
182 }
183 } else {
184 EvalResult.setValue(Ptr.toAPValue(ASTCtx: Ctx.getASTContext()));
185 }
186
187 return true;
188}
189template <> bool EvalEmitter::emitRet<PT_FnPtr>(const SourceInfo &Info) {
190 if (!isActive())
191 return true;
192
193 if (!checkReturnState(S))
194 return false;
195 // Function pointers cannot be converted to rvalues.
196 EvalResult.setFunctionPointer(S.Stk.pop<FunctionPointer>());
197 return true;
198}
199
200bool EvalEmitter::emitRetVoid(const SourceInfo &Info) {
201 if (!checkReturnState(S))
202 return false;
203 EvalResult.setValid();
204 return true;
205}
206
207bool EvalEmitter::emitRetValue(const SourceInfo &Info) {
208 const auto &Ptr = S.Stk.pop<Pointer>();
209
210 if (!EvalResult.checkReturnValue(S, Ctx, Ptr, Info))
211 return false;
212 if (CheckFullyInitialized && !EvalResult.checkFullyInitialized(S, Ptr))
213 return false;
214
215 if (!checkReturnState(S))
216 return false;
217
218 if (std::optional<APValue> APV =
219 Ptr.toRValue(Ctx: S.getCtx(), ResultType: EvalResult.getSourceType())) {
220 EvalResult.setValue(*APV);
221 return true;
222 }
223
224 EvalResult.setInvalid();
225 return false;
226}
227
228bool EvalEmitter::emitGetPtrLocal(uint32_t I, const SourceInfo &Info) {
229 if (!isActive())
230 return true;
231
232 Block *B = getLocal(Index: I);
233 S.Stk.push<Pointer>(Args&: B, Args: sizeof(InlineDescriptor));
234 return true;
235}
236
237template <PrimType OpType>
238bool EvalEmitter::emitGetLocal(uint32_t I, const SourceInfo &Info) {
239 if (!isActive())
240 return true;
241
242 using T = typename PrimConv<OpType>::T;
243
244 Block *B = getLocal(Index: I);
245 S.Stk.push<T>(*reinterpret_cast<T *>(B->data()));
246 return true;
247}
248
249template <PrimType OpType>
250bool EvalEmitter::emitSetLocal(uint32_t I, const SourceInfo &Info) {
251 if (!isActive())
252 return true;
253
254 using T = typename PrimConv<OpType>::T;
255
256 Block *B = getLocal(Index: I);
257 *reinterpret_cast<T *>(B->data()) = S.Stk.pop<T>();
258 InlineDescriptor &Desc = *reinterpret_cast<InlineDescriptor *>(B->rawData());
259 Desc.IsInitialized = true;
260
261 return true;
262}
263
264bool EvalEmitter::emitDestroy(uint32_t I, const SourceInfo &Info) {
265 if (!isActive())
266 return true;
267
268 for (auto &Local : Descriptors[I]) {
269 Block *B = getLocal(Index: Local.Offset);
270 S.deallocate(B);
271 }
272
273 return true;
274}
275
276/// Global temporaries (LifetimeExtendedTemporary) carry their value
277/// around as an APValue, which codegen accesses.
278/// We set their value once when creating them, but we don't update it
279/// afterwards when code changes it later.
280/// This is what we do here.
281void EvalEmitter::updateGlobalTemporaries() {
282 for (const auto &[E, Temp] : S.SeenGlobalTemporaries) {
283 if (std::optional<unsigned> GlobalIndex = P.getGlobal(E)) {
284 const Pointer &Ptr = P.getPtrGlobal(Idx: *GlobalIndex);
285 APValue *Cached = Temp->getOrCreateValue(MayCreate: true);
286
287 if (std::optional<PrimType> T = Ctx.classify(T: E->getType())) {
288 TYPE_SWITCH(
289 *T, { *Cached = Ptr.deref<T>().toAPValue(Ctx.getASTContext()); });
290 } else {
291 if (std::optional<APValue> APV =
292 Ptr.toRValue(Ctx, ResultType: Temp->getTemporaryExpr()->getType()))
293 *Cached = *APV;
294 }
295 }
296 }
297 S.SeenGlobalTemporaries.clear();
298}
299
300//===----------------------------------------------------------------------===//
301// Opcode evaluators
302//===----------------------------------------------------------------------===//
303
304#define GET_EVAL_IMPL
305#include "Opcodes.inc"
306#undef GET_EVAL_IMPL
307