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 "ByteCodeGenError.h"
17#include "Context.h"
18#include "InterpStack.h"
19#include "InterpState.h"
20#include "PrimType.h"
21#include "Program.h"
22#include "Source.h"
23#include "llvm/Support/Error.h"
24
25namespace clang {
26namespace interp {
27class Context;
28class SourceInfo;
29enum Opcode : uint32_t;
30
31/// An emitter which links the program to bytecode for later use.
32class ByteCodeEmitter {
33protected:
34  using LabelTy = uint32_t;
35  using AddrTy = uintptr_t;
36  using Local = Scope::Local;
37
38public:
39  /// Compiles the function into the module.
40  llvm::Expected<Function *> compileFunc(const FunctionDecl *F);
41
42protected:
43  ByteCodeEmitter(Context &Ctx, Program &P) : Ctx(Ctx), P(P) {}
44
45  virtual ~ByteCodeEmitter() {}
46
47  /// Define a label.
48  void emitLabel(LabelTy Label);
49  /// Create a label.
50  LabelTy getLabel() { return ++NextLabel; }
51
52  /// Methods implemented by the compiler.
53  virtual bool visitFunc(const FunctionDecl *E) = 0;
54  virtual bool visitExpr(const Expr *E) = 0;
55  virtual bool visitDecl(const VarDecl *E) = 0;
56
57  /// Bails out if a given node cannot be compiled.
58  bool bail(const Stmt *S) { return bail(S->getBeginLoc()); }
59  bool bail(const Decl *D) { return bail(D->getBeginLoc()); }
60  bool bail(const SourceLocation &Loc);
61
62  /// Emits jumps.
63  bool jumpTrue(const LabelTy &Label);
64  bool jumpFalse(const LabelTy &Label);
65  bool jump(const LabelTy &Label);
66  bool fallthrough(const LabelTy &Label);
67
68  /// Callback for local registration.
69  Local createLocal(Descriptor *D);
70
71  /// Parameter indices.
72  llvm::DenseMap<const ParmVarDecl *, unsigned> Params;
73  /// Local descriptors.
74  llvm::SmallVector<SmallVector<Local, 8>, 2> Descriptors;
75
76private:
77  /// Current compilation context.
78  Context &Ctx;
79  /// Program to link to.
80  Program &P;
81  /// Index of the next available label.
82  LabelTy NextLabel = 0;
83  /// Offset of the next local variable.
84  unsigned NextLocalOffset = 0;
85  /// Location of a failure.
86  llvm::Optional<SourceLocation> BailLocation;
87  /// Label information for linker.
88  llvm::DenseMap<LabelTy, unsigned> LabelOffsets;
89  /// Location of label relocations.
90  llvm::DenseMap<LabelTy, llvm::SmallVector<unsigned, 5>> LabelRelocs;
91  /// Program code.
92  std::vector<char> Code;
93  /// Opcode to expression mapping.
94  SourceMap SrcMap;
95
96  /// Returns the offset for a jump or records a relocation.
97  int32_t getOffset(LabelTy Label);
98
99  /// Emits an opcode.
100  template <typename... Tys>
101  bool emitOp(Opcode Op, const Tys &... Args, const SourceInfo &L);
102
103protected:
104#define GET_LINK_PROTO
105#include "Opcodes.inc"
106#undef GET_LINK_PROTO
107};
108
109} // namespace interp
110} // namespace clang
111
112#endif
113