xref: /freebsd/contrib/llvm-project/clang/lib/AST/Interp/Context.cpp (revision 7ef62cebc2f965b0f640263e179276928885e33d)
1 //===--- Context.cpp - Context for the constexpr 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 "Context.h"
10 #include "ByteCodeEmitter.h"
11 #include "ByteCodeExprGen.h"
12 #include "ByteCodeStmtGen.h"
13 #include "EvalEmitter.h"
14 #include "Interp.h"
15 #include "InterpFrame.h"
16 #include "InterpStack.h"
17 #include "PrimType.h"
18 #include "Program.h"
19 #include "clang/AST/Expr.h"
20 #include "clang/Basic/TargetInfo.h"
21 
22 using namespace clang;
23 using namespace clang::interp;
24 
25 Context::Context(ASTContext &Ctx) : Ctx(Ctx), P(new Program(*this)) {}
26 
27 Context::~Context() {}
28 
29 bool Context::isPotentialConstantExpr(State &Parent, const FunctionDecl *FD) {
30   assert(Stk.empty());
31   Function *Func = P->getFunction(FD);
32   if (!Func || !Func->hasBody()) {
33     if (auto R = ByteCodeStmtGen<ByteCodeEmitter>(*this, *P).compileFunc(FD)) {
34       Func = *R;
35     } else {
36       handleAllErrors(R.takeError(), [&Parent](ByteCodeGenError &Err) {
37         Parent.FFDiag(Err.getRange().getBegin(),
38                       diag::err_experimental_clang_interp_failed)
39             << Err.getRange();
40       });
41       return false;
42     }
43   }
44 
45   return Func->isConstexpr();
46 }
47 
48 bool Context::evaluateAsRValue(State &Parent, const Expr *E, APValue &Result) {
49   assert(Stk.empty());
50   ByteCodeExprGen<EvalEmitter> C(*this, *P, Parent, Stk, Result);
51   if (Check(Parent, C.interpretExpr(E))) {
52     assert(Stk.empty());
53     return true;
54   }
55 
56   Stk.clear();
57   return false;
58 }
59 
60 bool Context::evaluateAsInitializer(State &Parent, const VarDecl *VD,
61                                     APValue &Result) {
62   assert(Stk.empty());
63   ByteCodeExprGen<EvalEmitter> C(*this, *P, Parent, Stk, Result);
64   if (Check(Parent, C.interpretDecl(VD))) {
65     assert(Stk.empty());
66     return true;
67   }
68 
69   Stk.clear();
70   return false;
71 }
72 
73 const LangOptions &Context::getLangOpts() const { return Ctx.getLangOpts(); }
74 
75 std::optional<PrimType> Context::classify(QualType T) const {
76   if (T->isReferenceType() || T->isPointerType()) {
77     return PT_Ptr;
78   }
79 
80   if (T->isBooleanType())
81     return PT_Bool;
82 
83   if (T->isSignedIntegerOrEnumerationType()) {
84     switch (Ctx.getIntWidth(T)) {
85     case 64:
86       return PT_Sint64;
87     case 32:
88       return PT_Sint32;
89     case 16:
90       return PT_Sint16;
91     case 8:
92       return PT_Sint8;
93     default:
94       return {};
95     }
96   }
97 
98   if (T->isUnsignedIntegerOrEnumerationType()) {
99     switch (Ctx.getIntWidth(T)) {
100     case 64:
101       return PT_Uint64;
102     case 32:
103       return PT_Uint32;
104     case 16:
105       return PT_Uint16;
106     case 8:
107       return PT_Uint8;
108     default:
109       return {};
110     }
111   }
112 
113   if (T->isNullPtrType())
114     return PT_Ptr;
115 
116   if (auto *AT = dyn_cast<AtomicType>(T))
117     return classify(AT->getValueType());
118 
119   return {};
120 }
121 
122 unsigned Context::getCharBit() const {
123   return Ctx.getTargetInfo().getCharWidth();
124 }
125 
126 bool Context::Run(State &Parent, Function *Func, APValue &Result) {
127   InterpState State(Parent, *P, Stk, *this);
128   State.Current = new InterpFrame(State, Func, /*Caller=*/nullptr, {});
129   if (Interpret(State, Result))
130     return true;
131   Stk.clear();
132   return false;
133 }
134 
135 bool Context::Check(State &Parent, llvm::Expected<bool> &&Flag) {
136   if (Flag)
137     return *Flag;
138   handleAllErrors(Flag.takeError(), [&Parent](ByteCodeGenError &Err) {
139     Parent.FFDiag(Err.getRange().getBegin(),
140                   diag::err_experimental_clang_interp_failed)
141         << Err.getRange();
142   });
143   return false;
144 }
145