Source.h

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//===--- Source.h - Source location provider for the VM  --------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Defines a program which organises and links multiple bytecode functions.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_CLANG_AST_INTERP_SOURCE_H
#define LLVM_CLANG_AST_INTERP_SOURCE_H
 
#include "PrimType.h"
#include "clang/AST/DeclBase.h"
#include "clang/AST/Stmt.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Endian.h"
 
namespace clang {
class Expr;
class SourceLocation;
class SourceRange;
namespace interp {
class Function;
 
/// Pointer into the code segment.
class CodePtr final {
public:
  CodePtr() = default;
 
  CodePtr &operator+=(int32_t Offset) {
    Ptr += Offset;
    return *this;
  }
 
  CodePtr operator+(int32_t Offset) { return CodePtr(Ptr + Offset); }
 
  int32_t operator-(const CodePtr &RHS) const {
    assert(Ptr != nullptr && RHS.Ptr != nullptr && "Invalid code pointer");
    return Ptr - RHS.Ptr;
  }
 
  CodePtr operator-(size_t RHS) const {
    assert(Ptr != nullptr && "Invalid code pointer");
    return CodePtr(Ptr - RHS);
  }
 
  bool operator!=(const CodePtr &RHS) const { return Ptr != RHS.Ptr; }
  const std::byte *operator*() const { return Ptr; }
  explicit operator bool() const { return Ptr; }
  bool operator<=(const CodePtr &RHS) const { return Ptr <= RHS.Ptr; }
  bool operator>=(const CodePtr &RHS) const { return Ptr >= RHS.Ptr; }
  bool operator==(const CodePtr RHS) const { return Ptr == RHS.Ptr; }
 
  /// Reads data and advances the pointer.
  template <typename T> std::enable_if_t<!std::is_pointer<T>::value, T> read() {
    assert(aligned(Ptr));
    using namespace llvm::support;
    T Value = endian::read<T, llvm::endianness::native>(Ptr);
    Ptr += align(sizeof(T));
    return Value;
  }
 
private:
  friend class Function;
  /// Constructor used by Function to generate pointers.
  CodePtr(const std::byte *Ptr) : Ptr(Ptr) {}
  /// Pointer into the code owned by a function.
  const std::byte *Ptr = nullptr;
};
 
/// Describes the statement/declaration an opcode was generated from.
class SourceInfo final {
public:
  SourceInfo() {}
  SourceInfo(const Stmt *E) : Source(E) {}
  SourceInfo(const Decl *D) : Source(D) {}
 
  SourceLocation getLoc() const;
  SourceRange getRange() const;
 
  const Stmt *asStmt() const {
    return dyn_cast_if_present<const Stmt *>(Source);
  }
  const Decl *asDecl() const {
    return dyn_cast_if_present<const Decl *>(Source);
  }
  const Expr *asExpr() const { return dyn_cast_if_present<Expr>(asStmt()); }
 
  operator bool() const { return !Source.isNull(); }
 
private:
  llvm::PointerUnion<const Decl *, const Stmt *> Source;
};
static_assert(sizeof(SourceInfo) == sizeof(void *));
 
// A map from byte code offset to source information.
// This is used to get the location in the input source file for diagnostics.
class SourceMap final {
private:
  llvm::SmallVector<uint32_t> Offsets;
  llvm::SmallVector<SourceInfo> Infos;
 
public:
  SourceMap() = default;
  void push(uint32_t Offset, SourceInfo Info) {
    Offsets.push_back(Offset);
    Infos.push_back(Info);
  }
 
  SourceInfo findSourceForOffset(uint32_t Offset) const {
    assert(!Offsets.empty());
    assert(Offsets.size() == Infos.size());
#ifndef NDEBUG
    assert(llvm::is_sorted(Offsets));
#endif
    const auto *It = llvm::lower_bound(Offsets, Offset);
    return Infos[It - Offsets.begin()];
  }
};
 
/// Interface for classes which map locations to sources.
class SourceMapper {
public:
  virtual ~SourceMapper() {}
 
  /// Returns source information for a given PC in a function.
  virtual SourceInfo getSource(CodePtr PC) const = 0;
 
  /// Returns the expression if an opcode belongs to one, null otherwise.
  const Expr *getExpr(CodePtr PC) const;
  /// Returns the location from which an opcode originates.
  SourceLocation getLocation(CodePtr PC) const;
  SourceRange getRange(CodePtr PC) const;
};
 
} // namespace interp
} // namespace clang
 
#endif