clang/lib/AST/Interp/ByteCodeEmitter.h

   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 #include "llvm/Support/Error.h"
  21
  22 namespace clang {
  23 namespace interp {
  24 enum Opcode : uint32_t;
  25
  26 /// An emitter which links the program to bytecode for later use.
  27 class ByteCodeEmitter {
  28 protected:
  29   using LabelTy = uint32_t;
  30   using AddrTy = uintptr_t;
  31   using Local = Scope::Local;
  32
  33 public:
  34   /// Compiles the function into the module.
  35   llvm::Expected<Function *> compileFunc(const FunctionDecl *FuncDecl);
  36
  37 protected:
  38   ByteCodeEmitter(Context &Ctx, Program &P) : Ctx(Ctx), P(P) {}
  39
  40   virtual ~ByteCodeEmitter() {}
  41
  42   /// Define a label.
  43   void emitLabel(LabelTy Label);
  44   /// Create a label.
  45   LabelTy getLabel() { return ++NextLabel; }
  46
  47   /// Methods implemented by the compiler.
  48   virtual bool visitFunc(const FunctionDecl *E) = 0;
  49   virtual bool visitExpr(const Expr *E) = 0;
  50   virtual bool visitDecl(const VarDecl *E) = 0;
  51
  52   /// Bails out if a given node cannot be compiled.
  53   bool bail(const Stmt *S) { return bail(S->getBeginLoc()); }
  54   bool bail(const Decl *D) { return bail(D->getBeginLoc()); }
  55   bool bail(const SourceLocation &Loc);
  56
  57   /// Emits jumps.
  58   bool jumpTrue(const LabelTy &Label);
  59   bool jumpFalse(const LabelTy &Label);
  60   bool jump(const LabelTy &Label);
  61   bool fallthrough(const LabelTy &Label);
  62
  63   /// Callback for local registration.
  64   Local createLocal(Descriptor *D);
  65
  66   /// Parameter indices.
  67   llvm::DenseMap<const ParmVarDecl *, ParamOffset> Params;
  68   /// Lambda captures.
  69   llvm::DenseMap<const ValueDecl *, ParamOffset> LambdaCaptures;
  70   /// Offset of the This parameter in a lambda record.
  71   unsigned LambdaThisCapture = 0;
  72   /// Local descriptors.
  73   llvm::SmallVector<SmallVector<Local, 8>, 2> Descriptors;
  74
  75 private:
  76   /// Current compilation context.
  77   Context &Ctx;
  78   /// Program to link to.
  79   Program &P;
  80   /// Index of the next available label.
  81   LabelTy NextLabel = 0;
  82   /// Offset of the next local variable.
  83   unsigned NextLocalOffset = 0;
  84   /// Location of a failure.
  85   std::optional<SourceLocation> BailLocation;
  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
 102 protected:
 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