1 //===--- Integral.h - Wrapper for numeric types 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 VM types and helpers operating on types.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #ifndef LLVM_CLANG_AST_INTERP_INTEGRAL_H
14 #define LLVM_CLANG_AST_INTERP_INTEGRAL_H
15
16 #include "clang/AST/ComparisonCategories.h"
17 #include "clang/AST/APValue.h"
18 #include "llvm/ADT/APSInt.h"
19 #include "llvm/Support/MathExtras.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include <cstddef>
22 #include <cstdint>
23
24 namespace clang {
25 namespace interp {
26
27 using APInt = llvm::APInt;
28 using APSInt = llvm::APSInt;
29
30 /// Helper to compare two comparable types.
31 template <typename T>
Compare(const T & X,const T & Y)32 ComparisonCategoryResult Compare(const T &X, const T &Y) {
33 if (X < Y)
34 return ComparisonCategoryResult::Less;
35 if (X > Y)
36 return ComparisonCategoryResult::Greater;
37 return ComparisonCategoryResult::Equal;
38 }
39
40 // Helper structure to select the representation.
41 template <unsigned Bits, bool Signed> struct Repr;
42 template <> struct Repr<8, false> { using Type = uint8_t; };
43 template <> struct Repr<16, false> { using Type = uint16_t; };
44 template <> struct Repr<32, false> { using Type = uint32_t; };
45 template <> struct Repr<64, false> { using Type = uint64_t; };
46 template <> struct Repr<8, true> { using Type = int8_t; };
47 template <> struct Repr<16, true> { using Type = int16_t; };
48 template <> struct Repr<32, true> { using Type = int32_t; };
49 template <> struct Repr<64, true> { using Type = int64_t; };
50
51 /// Wrapper around numeric types.
52 ///
53 /// These wrappers are required to shared an interface between APSint and
54 /// builtin primitive numeral types, while optimising for storage and
55 /// allowing methods operating on primitive type to compile to fast code.
56 template <unsigned Bits, bool Signed> class Integral {
57 private:
58 template <unsigned OtherBits, bool OtherSigned> friend class Integral;
59
60 // The primitive representing the integral.
61 using T = typename Repr<Bits, Signed>::Type;
62 T V;
63
64 /// Primitive representing limits.
65 static const auto Min = std::numeric_limits<T>::min();
66 static const auto Max = std::numeric_limits<T>::max();
67
68 /// Construct an integral from anything that is convertible to storage.
69 template <typename T> explicit Integral(T V) : V(V) {}
70
71 public:
72 /// Zero-initializes an integral.
73 Integral() : V(0) {}
74
75 /// Constructs an integral from another integral.
76 template <unsigned SrcBits, bool SrcSign>
77 explicit Integral(Integral<SrcBits, SrcSign> V) : V(V.V) {}
78
79 /// Construct an integral from a value based on signedness.
80 explicit Integral(const APSInt &V)
81 : V(V.isSigned() ? V.getSExtValue() : V.getZExtValue()) {}
82
83 bool operator<(Integral RHS) const { return V < RHS.V; }
84 bool operator>(Integral RHS) const { return V > RHS.V; }
85 bool operator<=(Integral RHS) const { return V <= RHS.V; }
86 bool operator>=(Integral RHS) const { return V >= RHS.V; }
87 bool operator==(Integral RHS) const { return V == RHS.V; }
88 bool operator!=(Integral RHS) const { return V != RHS.V; }
89
90 bool operator>(unsigned RHS) const {
91 return V >= 0 && static_cast<unsigned>(V) > RHS;
92 }
93
94 Integral operator-() const { return Integral(-V); }
95 Integral operator~() const { return Integral(~V); }
96
97 template <unsigned DstBits, bool DstSign>
98 explicit operator Integral<DstBits, DstSign>() const {
99 return Integral<DstBits, DstSign>(V);
100 }
101
102 explicit operator unsigned() const { return V; }
103 explicit operator int64_t() const { return V; }
104 explicit operator uint64_t() const { return V; }
105
106 APSInt toAPSInt() const {
107 return APSInt(APInt(Bits, static_cast<uint64_t>(V), Signed), !Signed);
108 }
109 APSInt toAPSInt(unsigned NumBits) const {
110 if (Signed)
111 return APSInt(toAPSInt().sextOrTrunc(NumBits), !Signed);
112 else
113 return APSInt(toAPSInt().zextOrTrunc(NumBits), !Signed);
114 }
115 APValue toAPValue() const { return APValue(toAPSInt()); }
116
117 Integral<Bits, false> toUnsigned() const {
118 return Integral<Bits, false>(*this);
119 }
120
121 constexpr static unsigned bitWidth() { return Bits; }
122
123 bool isZero() const { return !V; }
124
125 bool isMin() const { return *this == min(bitWidth()); }
126
127 bool isMinusOne() const { return Signed && V == T(-1); }
128
129 constexpr static bool isSigned() { return Signed; }
130
131 bool isNegative() const { return V < T(0); }
132 bool isPositive() const { return !isNegative(); }
133
134 ComparisonCategoryResult compare(const Integral &RHS) const {
135 return Compare(V, RHS.V);
136 }
137
138 unsigned countLeadingZeros() const { return llvm::countLeadingZeros<T>(V); }
139
140 Integral truncate(unsigned TruncBits) const {
141 if (TruncBits >= Bits)
142 return *this;
143 const T BitMask = (T(1) << T(TruncBits)) - 1;
144 const T SignBit = T(1) << (TruncBits - 1);
145 const T ExtMask = ~BitMask;
146 return Integral((V & BitMask) | (Signed && (V & SignBit) ? ExtMask : 0));
147 }
148
149 void print(llvm::raw_ostream &OS) const { OS << V; }
150
151 static Integral min(unsigned NumBits) {
152 return Integral(Min);
153 }
154 static Integral max(unsigned NumBits) {
155 return Integral(Max);
156 }
157
158 template <typename T>
159 static std::enable_if_t<std::is_integral<T>::value, Integral> from(T Value) {
160 return Integral(Value);
161 }
162
163 template <unsigned SrcBits, bool SrcSign>
164 static std::enable_if_t<SrcBits != 0, Integral>
165 from(Integral<SrcBits, SrcSign> Value) {
166 return Integral(Value.V);
167 }
168
169 template <bool SrcSign> static Integral from(Integral<0, SrcSign> Value) {
170 if (SrcSign)
171 return Integral(Value.V.getSExtValue());
172 else
173 return Integral(Value.V.getZExtValue());
174 }
175
176 static Integral zero() { return from(0); }
177
178 template <typename T> static Integral from(T Value, unsigned NumBits) {
179 return Integral(Value);
180 }
181
182 static bool inRange(int64_t Value, unsigned NumBits) {
183 return CheckRange<T, Min, Max>(Value);
184 }
185
186 static bool increment(Integral A, Integral *R) {
187 return add(A, Integral(T(1)), A.bitWidth(), R);
188 }
189
190 static bool decrement(Integral A, Integral *R) {
191 return sub(A, Integral(T(1)), A.bitWidth(), R);
192 }
193
194 static bool add(Integral A, Integral B, unsigned OpBits, Integral *R) {
195 return CheckAddUB(A.V, B.V, R->V);
196 }
197
198 static bool sub(Integral A, Integral B, unsigned OpBits, Integral *R) {
199 return CheckSubUB(A.V, B.V, R->V);
200 }
201
202 static bool mul(Integral A, Integral B, unsigned OpBits, Integral *R) {
203 return CheckMulUB(A.V, B.V, R->V);
204 }
205
206 private:
207 template <typename T>
208 static std::enable_if_t<std::is_signed<T>::value, bool> CheckAddUB(T A, T B,
209 T &R) {
210 return llvm::AddOverflow<T>(A, B, R);
211 }
212
213 template <typename T>
214 static std::enable_if_t<std::is_unsigned<T>::value, bool> CheckAddUB(T A, T B,
215 T &R) {
216 R = A + B;
217 return false;
218 }
219
220 template <typename T>
221 static std::enable_if_t<std::is_signed<T>::value, bool> CheckSubUB(T A, T B,
222 T &R) {
223 return llvm::SubOverflow<T>(A, B, R);
224 }
225
226 template <typename T>
227 static std::enable_if_t<std::is_unsigned<T>::value, bool> CheckSubUB(T A, T B,
228 T &R) {
229 R = A - B;
230 return false;
231 }
232
233 template <typename T>
234 static std::enable_if_t<std::is_signed<T>::value, bool> CheckMulUB(T A, T B,
235 T &R) {
236 return llvm::MulOverflow<T>(A, B, R);
237 }
238
239 template <typename T>
240 static std::enable_if_t<std::is_unsigned<T>::value, bool> CheckMulUB(T A, T B,
241 T &R) {
242 R = A * B;
243 return false;
244 }
245
246 template <typename T, T Min, T Max>
247 static std::enable_if_t<std::is_signed<T>::value, bool>
248 CheckRange(int64_t V) {
249 return Min <= V && V <= Max;
250 }
251
252 template <typename T, T Min, T Max>
253 static std::enable_if_t<std::is_unsigned<T>::value, bool>
254 CheckRange(int64_t V) {
255 return V >= 0 && static_cast<uint64_t>(V) <= Max;
256 }
257 };
258
259 template <unsigned Bits, bool Signed>
260 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, Integral<Bits, Signed> I) {
261 I.print(OS);
262 return OS;
263 }
264
265 } // namespace interp
266 } // namespace clang
267
268 #endif
269