APNumericStorage.h

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//===--- APNumericStorage.h - Store APInt/APFloat in ASTContext -*- 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
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_CLANG_AST_APNUMERICSTORAGE_H
#define LLVM_CLANG_AST_APNUMERICSTORAGE_H
 
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
 
namespace clang {
class ASTContext;
 
/// Used by IntegerLiteral/FloatingLiteral/EnumConstantDecl to store the
/// numeric without leaking memory.
///
/// For large floats/integers, APFloat/APInt will allocate memory from the heap
/// to represent these numbers.  Unfortunately, when we use a BumpPtrAllocator
/// to allocate IntegerLiteral/FloatingLiteral nodes the memory associated with
/// the APFloat/APInt values will never get freed. APNumericStorage uses
/// ASTContext's allocator for memory allocation.
class APNumericStorage {
  union {
    uint64_t VAL;   ///< Used to store the <= 64 bits integer value.
    uint64_t *pVal; ///< Used to store the >64 bits integer value.
  };
 
  bool hasAllocation() const { return llvm::APInt::getNumWords(BitWidth) > 1; }
 
  APNumericStorage(const APNumericStorage &) = delete;
  void operator=(const APNumericStorage &) = delete;
 
protected:
  unsigned BitWidth;
  APNumericStorage() : VAL(0), BitWidth(0) {}
 
  llvm::APInt getIntValue() const {
    unsigned NumWords = llvm::APInt::getNumWords(BitWidth);
    if (NumWords > 1)
      return llvm::APInt(BitWidth, llvm::ArrayRef(pVal, NumWords));
    return llvm::APInt(BitWidth, VAL);
  }
  void setIntValue(const ASTContext &C, const llvm::APInt &Val);
};
 
class APIntStorage : private APNumericStorage {
public:
  llvm::APInt getValue() const { return getIntValue(); }
  unsigned getBitWidth() const { return BitWidth; }
  void setValue(const ASTContext &C, const llvm::APInt &Val) {
    setIntValue(C, Val);
  }
};
 
class APFloatStorage : private APNumericStorage {
public:
  llvm::APFloat getValue(const llvm::fltSemantics &Semantics) const {
    return llvm::APFloat(Semantics, getIntValue());
  }
  void setValue(const ASTContext &C, const llvm::APFloat &Val) {
    setIntValue(C, Val.bitcastToAPInt());
  }
};
 
} // end namespace clang
 
#endif // LLVM_CLANG_AST_APNUMERICSTORAGE_H