1//===--- ByteCodeEmitter.h - 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// Defines the instruction emitters.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_CLANG_AST_INTERP_LINKEMITTER_H
14#define LLVM_CLANG_AST_INTERP_LINKEMITTER_H
15
16#include "Context.h"
17#include "PrimType.h"
18#include "Program.h"
19#include "Source.h"
20
21namespace clang {
22namespace interp {
23enum Opcode : uint32_t;
24
25/// An emitter which links the program to bytecode for later use.
26class ByteCodeEmitter {
27protected:
28 using LabelTy = uint32_t;
29 using AddrTy = uintptr_t;
30 using Local = Scope::Local;
31
32public:
33 /// Compiles the function into the module.
34 void compileFunc(const FunctionDecl *FuncDecl, Function *Func = nullptr);
35
36protected:
37 ByteCodeEmitter(Context &Ctx, Program &P) : Ctx(Ctx), P(P) {}
38
39 virtual ~ByteCodeEmitter() {}
40
41 /// Define a label.
42 void emitLabel(LabelTy Label);
43 /// Create a label.
44 LabelTy getLabel() { return ++NextLabel; }
45
46 /// Methods implemented by the compiler.
47 virtual bool visitFunc(const FunctionDecl *E) = 0;
48 virtual bool visitExpr(const Expr *E, bool DestroyToplevelScope) = 0;
49 virtual bool visitDeclAndReturn(const VarDecl *E, bool ConstantContext) = 0;
50 virtual bool visit(const Expr *E) = 0;
51 virtual bool emitBool(bool V, const Expr *E) = 0;
52
53 /// Emits jumps.
54 bool jumpTrue(const LabelTy &Label);
55 bool jumpFalse(const LabelTy &Label);
56 bool jump(const LabelTy &Label);
57 bool fallthrough(const LabelTy &Label);
58 /// Speculative execution.
59 bool speculate(const CallExpr *E, const LabelTy &EndLabel);
60
61 /// We're always emitting bytecode.
62 bool isActive() const { return true; }
63 bool checkingForUndefinedBehavior() const { return false; }
64
65 /// Callback for local registration.
66 Local createLocal(Descriptor *D);
67
68 /// Parameter indices.
69 llvm::DenseMap<const ParmVarDecl *, ParamOffset> Params;
70 /// Lambda captures.
71 llvm::DenseMap<const ValueDecl *, ParamOffset> LambdaCaptures;
72 /// Offset of the This parameter in a lambda record.
73 ParamOffset LambdaThisCapture{.Offset: 0, .IsPtr: false};
74 /// Local descriptors.
75 llvm::SmallVector<SmallVector<Local, 8>, 2> Descriptors;
76
77private:
78 /// Current compilation context.
79 Context &Ctx;
80 /// Program to link to.
81 Program &P;
82 /// Index of the next available label.
83 LabelTy NextLabel = 0;
84 /// Offset of the next local variable.
85 unsigned NextLocalOffset = 0;
86 /// Label information for linker.
87 llvm::DenseMap<LabelTy, unsigned> LabelOffsets;
88 /// Location of label relocations.
89 llvm::DenseMap<LabelTy, llvm::SmallVector<unsigned, 5>> LabelRelocs;
90 /// Program code.
91 std::vector<std::byte> Code;
92 /// Opcode to expression mapping.
93 SourceMap SrcMap;
94
95 /// Returns the offset for a jump or records a relocation.
96 int32_t getOffset(LabelTy Label);
97
98 /// Emits an opcode.
99 template <typename... Tys>
100 bool emitOp(Opcode Op, const Tys &...Args, const SourceInfo &L);
101
102protected:
103#define GET_LINK_PROTO
104#include "Opcodes.inc"
105#undef GET_LINK_PROTO
106};
107
108} // namespace interp
109} // namespace clang
110
111#endif
112