1 //===-- Scalar.h ------------------------------------------------*- 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 #ifndef LLDB_UTILITY_SCALAR_H
10 #define LLDB_UTILITY_SCALAR_H
11 
12 #include "lldb/Utility/LLDBAssert.h"
13 #include "lldb/Utility/Status.h"
14 #include "lldb/lldb-enumerations.h"
15 #include "lldb/lldb-private-types.h"
16 #include "llvm/ADT/APFloat.h"
17 #include "llvm/ADT/APSInt.h"
18 #include <cstddef>
19 #include <cstdint>
20 #include <utility>
21 
22 namespace lldb_private {
23 
24 class DataExtractor;
25 class Stream;
26 
27 #define NUM_OF_WORDS_INT128 2
28 #define BITWIDTH_INT128 128
29 
30 // A class designed to hold onto values and their corresponding types.
31 // Operators are defined and Scalar objects will correctly promote their types
32 // and values before performing these operations. Type promotion currently
33 // follows the ANSI C type promotion rules.
34 class Scalar {
35   template<typename T>
36   static llvm::APSInt MakeAPSInt(T v) {
37     static_assert(std::is_integral<T>::value);
38     static_assert(sizeof(T) <= sizeof(uint64_t), "Conversion loses precision!");
39     return llvm::APSInt(
40         llvm::APInt(sizeof(T) * 8, uint64_t(v), std::is_signed<T>::value),
41         std::is_unsigned<T>::value);
42   }
43 
44 public:
45   enum Type {
46     e_void = 0,
47     e_int,
48     e_float,
49   };
50 
51   // Constructors and Destructors
52   Scalar() : m_float(0.0f) {}
53   Scalar(int v) : m_type(e_int), m_integer(MakeAPSInt(v)), m_float(0.0f) {}
54   Scalar(unsigned int v)
55       : m_type(e_int), m_integer(MakeAPSInt(v)), m_float(0.0f) {}
56   Scalar(long v) : m_type(e_int), m_integer(MakeAPSInt(v)), m_float(0.0f) {}
57   Scalar(unsigned long v)
58       : m_type(e_int), m_integer(MakeAPSInt(v)), m_float(0.0f) {}
59   Scalar(long long v)
60       : m_type(e_int), m_integer(MakeAPSInt(v)), m_float(0.0f) {}
61   Scalar(unsigned long long v)
62       : m_type(e_int), m_integer(MakeAPSInt(v)), m_float(0.0f) {}
63   Scalar(float v) : m_type(e_float), m_float(v) {}
64   Scalar(double v) : m_type(e_float), m_float(v) {}
65   Scalar(long double v) : m_type(e_float), m_float(double(v)) {
66     bool ignore;
67     m_float.convert(llvm::APFloat::x87DoubleExtended(),
68                     llvm::APFloat::rmNearestTiesToEven, &ignore);
69   }
70   Scalar(llvm::APInt v)
71       : m_type(e_int), m_integer(std::move(v), false), m_float(0.0f) {}
72   Scalar(llvm::APSInt v)
73       : m_type(e_int), m_integer(std::move(v)), m_float(0.0f) {}
74 
75   bool SignExtend(uint32_t bit_pos);
76 
77   bool ExtractBitfield(uint32_t bit_size, uint32_t bit_offset);
78 
79   bool SetBit(uint32_t bit);
80 
81   bool ClearBit(uint32_t bit);
82 
83   /// Store the binary representation of this value into the given storage.
84   /// Exactly GetByteSize() bytes will be stored, and the buffer must be large
85   /// enough to hold this data.
86   void GetBytes(llvm::MutableArrayRef<uint8_t> storage) const;
87 
88   size_t GetByteSize() const;
89 
90   bool GetData(DataExtractor &data, size_t limit_byte_size = UINT32_MAX) const;
91 
92   size_t GetAsMemoryData(void *dst, size_t dst_len,
93                          lldb::ByteOrder dst_byte_order, Status &error) const;
94 
95   bool IsZero() const;
96 
97   void Clear() {
98     m_type = e_void;
99     m_integer.clearAllBits();
100   }
101 
102   const char *GetTypeAsCString() const { return GetValueTypeAsCString(m_type); }
103 
104   void GetValue(Stream *s, bool show_type) const;
105 
106   bool IsValid() const { return (m_type >= e_int) && (m_type <= e_float); }
107 
108   /// Convert to an integer with \p bits and the given signedness.
109   void TruncOrExtendTo(uint16_t bits, bool sign);
110 
111   bool IntegralPromote(uint16_t bits, bool sign);
112   bool FloatPromote(const llvm::fltSemantics &semantics);
113 
114   bool IsSigned() const;
115   bool MakeSigned();
116 
117   bool MakeUnsigned();
118 
119   static const char *GetValueTypeAsCString(Scalar::Type value_type);
120 
121   // All operators can benefits from the implicit conversions that will happen
122   // automagically by the compiler, so no temporary objects will need to be
123   // created. As a result, we currently don't need a variety of overloaded set
124   // value accessors.
125   Scalar &operator+=(Scalar rhs);
126   Scalar &operator<<=(const Scalar &rhs); // Shift left
127   Scalar &operator>>=(const Scalar &rhs); // Shift right (arithmetic)
128   Scalar &operator&=(const Scalar &rhs);
129 
130   // Shifts the current value to the right without maintaining the current sign
131   // of the value (if it is signed).
132   bool ShiftRightLogical(const Scalar &rhs); // Returns true on success
133 
134   // Takes the absolute value of the current value if it is signed, else the
135   // value remains unchanged. Returns false if the contained value has a void
136   // type.
137   bool AbsoluteValue(); // Returns true on success
138   // Negates the current value (even for unsigned values). Returns false if the
139   // contained value has a void type.
140   bool UnaryNegate(); // Returns true on success
141   // Inverts all bits in the current value as long as it isn't void or a
142   // float/double/long double type. Returns false if the contained value has a
143   // void/float/double/long double type, else the value is inverted and true is
144   // returned.
145   bool OnesComplement(); // Returns true on success
146 
147   // Access the type of the current value.
148   Scalar::Type GetType() const { return m_type; }
149 
150   // Returns a casted value of the current contained data without modifying the
151   // current value. FAIL_VALUE will be returned if the type of the value is
152   // void or invalid.
153   int SInt(int fail_value = 0) const;
154 
155   unsigned char UChar(unsigned char fail_value = 0) const;
156 
157   signed char SChar(signed char fail_value = 0) const;
158 
159   unsigned short UShort(unsigned short fail_value = 0) const;
160 
161   short SShort(short fail_value = 0) const;
162 
163   unsigned int UInt(unsigned int fail_value = 0) const;
164 
165   long SLong(long fail_value = 0) const;
166 
167   unsigned long ULong(unsigned long fail_value = 0) const;
168 
169   long long SLongLong(long long fail_value = 0) const;
170 
171   unsigned long long ULongLong(unsigned long long fail_value = 0) const;
172 
173   llvm::APInt SInt128(const llvm::APInt &fail_value) const;
174 
175   llvm::APInt UInt128(const llvm::APInt &fail_value) const;
176 
177   float Float(float fail_value = 0.0f) const;
178 
179   double Double(double fail_value = 0.0) const;
180 
181   long double LongDouble(long double fail_value = 0.0) const;
182 
183   Status SetValueFromCString(const char *s, lldb::Encoding encoding,
184                              size_t byte_size);
185 
186   Status SetValueFromData(const DataExtractor &data, lldb::Encoding encoding,
187                           size_t byte_size);
188 
189 protected:
190   Scalar::Type m_type = e_void;
191   llvm::APSInt m_integer;
192   llvm::APFloat m_float;
193 
194   template <typename T> T GetAs(T fail_value) const;
195 
196   static Type PromoteToMaxType(Scalar &lhs, Scalar &rhs);
197 
198   using PromotionKey = std::tuple<Type, unsigned, bool>;
199   PromotionKey GetPromoKey() const;
200 
201   static PromotionKey GetFloatPromoKey(const llvm::fltSemantics &semantics);
202 
203 private:
204   friend const Scalar operator+(const Scalar &lhs, const Scalar &rhs);
205   friend const Scalar operator-(Scalar lhs, Scalar rhs);
206   friend const Scalar operator/(Scalar lhs, Scalar rhs);
207   friend const Scalar operator*(Scalar lhs, Scalar rhs);
208   friend const Scalar operator&(Scalar lhs, Scalar rhs);
209   friend const Scalar operator|(Scalar lhs, Scalar rhs);
210   friend const Scalar operator%(Scalar lhs, Scalar rhs);
211   friend const Scalar operator^(Scalar lhs, Scalar rhs);
212   friend const Scalar operator<<(const Scalar &lhs, const Scalar &rhs);
213   friend const Scalar operator>>(const Scalar &lhs, const Scalar &rhs);
214   friend bool operator==(Scalar lhs, Scalar rhs);
215   friend bool operator!=(const Scalar &lhs, const Scalar &rhs);
216   friend bool operator<(Scalar lhs, Scalar rhs);
217   friend bool operator<=(const Scalar &lhs, const Scalar &rhs);
218   friend bool operator>(const Scalar &lhs, const Scalar &rhs);
219   friend bool operator>=(const Scalar &lhs, const Scalar &rhs);
220 };
221 
222 // Split out the operators into a format where the compiler will be able to
223 // implicitly convert numbers into Scalar objects.
224 //
225 // This allows code like:
226 //      Scalar two(2);
227 //      Scalar four = two * 2;
228 //      Scalar eight = 2 * four;    // This would cause an error if the
229 //                                  // operator* was implemented as a
230 //                                  // member function.
231 // SEE:
232 //  Item 19 of "Effective C++ Second Edition" by Scott Meyers
233 //  Differentiate among members functions, non-member functions, and
234 //  friend functions
235 const Scalar operator+(const Scalar &lhs, const Scalar &rhs);
236 const Scalar operator-(Scalar lhs, Scalar rhs);
237 const Scalar operator/(Scalar lhs, Scalar rhs);
238 const Scalar operator*(Scalar lhs, Scalar rhs);
239 const Scalar operator&(Scalar lhs, Scalar rhs);
240 const Scalar operator|(Scalar lhs, Scalar rhs);
241 const Scalar operator%(Scalar lhs, Scalar rhs);
242 const Scalar operator^(Scalar lhs, Scalar rhs);
243 const Scalar operator<<(const Scalar &lhs, const Scalar &rhs);
244 const Scalar operator>>(const Scalar &lhs, const Scalar &rhs);
245 bool operator==(Scalar lhs, Scalar rhs);
246 bool operator!=(const Scalar &lhs, const Scalar &rhs);
247 bool operator<(Scalar lhs, Scalar rhs);
248 bool operator<=(const Scalar &lhs, const Scalar &rhs);
249 bool operator>(const Scalar &lhs, const Scalar &rhs);
250 bool operator>=(const Scalar &lhs, const Scalar &rhs);
251 
252 llvm::raw_ostream &operator<<(llvm::raw_ostream &os, const Scalar &scalar);
253 
254 } // namespace lldb_private
255 
256 #endif // LLDB_UTILITY_SCALAR_H
257