xref: /freebsd/contrib/llvm-project/clang/lib/AST/Interp/Integral.h (revision cccdaf507eee8fb34494b4624eb85bb951e323c8) 
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>
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 final {
57 private:
58   template <unsigned OtherBits, bool OtherSigned> friend class Integral;
59 
60   // The primitive representing the integral.
61   using ReprT = typename Repr<Bits, Signed>::Type;
62   ReprT V;
63 
64   /// Primitive representing limits.
65   static const auto Min = std::numeric_limits<ReprT>::min();
66   static const auto Max = std::numeric_limits<ReprT>::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 constexpr (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 == ReprT(-1); }
128 
129   constexpr static bool isSigned() { return Signed; }
130 
131   bool isNegative() const { return V < ReprT(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 {
139     return llvm::countLeadingZeros<ReprT>(V);
140   }
141 
142   Integral truncate(unsigned TruncBits) const {
143     if (TruncBits >= Bits)
144       return *this;
145     const ReprT BitMask = (ReprT(1) << ReprT(TruncBits)) - 1;
146     const ReprT SignBit = ReprT(1) << (TruncBits - 1);
147     const ReprT ExtMask = ~BitMask;
148     return Integral((V & BitMask) | (Signed && (V & SignBit) ? ExtMask : 0));
149   }
150 
151   void print(llvm::raw_ostream &OS) const { OS << V; }
152 
153   static Integral min(unsigned NumBits) {
154     return Integral(Min);
155   }
156   static Integral max(unsigned NumBits) {
157     return Integral(Max);
158   }
159 
160   template <typename ValT> static Integral from(ValT Value) {
161     if constexpr (std::is_integral<ValT>::value)
162       return Integral(Value);
163     else
164       return Integral::from(static_cast<Integral::ReprT>(Value));
165   }
166 
167   template <unsigned SrcBits, bool SrcSign>
168   static std::enable_if_t<SrcBits != 0, Integral>
169   from(Integral<SrcBits, SrcSign> Value) {
170     return Integral(Value.V);
171   }
172 
173   template <bool SrcSign> static Integral from(Integral<0, SrcSign> Value) {
174     if constexpr (SrcSign)
175       return Integral(Value.V.getSExtValue());
176     else
177       return Integral(Value.V.getZExtValue());
178   }
179 
180   static Integral zero() { return from(0); }
181 
182   template <typename T> static Integral from(T Value, unsigned NumBits) {
183     return Integral(Value);
184   }
185 
186   static bool inRange(int64_t Value, unsigned NumBits) {
187     return CheckRange<ReprT, Min, Max>(Value);
188   }
189 
190   static bool increment(Integral A, Integral *R) {
191     return add(A, Integral(ReprT(1)), A.bitWidth(), R);
192   }
193 
194   static bool decrement(Integral A, Integral *R) {
195     return sub(A, Integral(ReprT(1)), A.bitWidth(), R);
196   }
197 
198   static bool add(Integral A, Integral B, unsigned OpBits, Integral *R) {
199     return CheckAddUB(A.V, B.V, R->V);
200   }
201 
202   static bool sub(Integral A, Integral B, unsigned OpBits, Integral *R) {
203     return CheckSubUB(A.V, B.V, R->V);
204   }
205 
206   static bool mul(Integral A, Integral B, unsigned OpBits, Integral *R) {
207     return CheckMulUB(A.V, B.V, R->V);
208   }
209 
210   static bool rem(Integral A, Integral B, unsigned OpBits, Integral *R) {
211     *R = Integral(A.V % B.V);
212     return false;
213   }
214 
215   static bool div(Integral A, Integral B, unsigned OpBits, Integral *R) {
216     *R = Integral(A.V / B.V);
217     return false;
218   }
219 
220   static bool bitAnd(Integral A, Integral B, unsigned OpBits, Integral *R) {
221     *R = Integral(A.V & B.V);
222     return false;
223   }
224 
225   static bool bitOr(Integral A, Integral B, unsigned OpBits, Integral *R) {
226     *R = Integral(A.V | B.V);
227     return false;
228   }
229 
230   static bool bitXor(Integral A, Integral B, unsigned OpBits, Integral *R) {
231     *R = Integral(A.V ^ B.V);
232     return false;
233   }
234 
235   static bool neg(Integral A, Integral *R) {
236     *R = -A;
237     return false;
238   }
239 
240   static bool comp(Integral A, Integral *R) {
241     *R = Integral(~A.V);
242     return false;
243   }
244 
245 private:
246   template <typename T> static bool CheckAddUB(T A, T B, T &R) {
247     if constexpr (std::is_signed_v<T>) {
248       return llvm::AddOverflow<T>(A, B, R);
249     } else {
250       R = A + B;
251       return false;
252     }
253   }
254 
255   template <typename T> static bool CheckSubUB(T A, T B, T &R) {
256     if constexpr (std::is_signed_v<T>) {
257       return llvm::SubOverflow<T>(A, B, R);
258     } else {
259       R = A - B;
260       return false;
261     }
262   }
263 
264   template <typename T> static bool CheckMulUB(T A, T B, T &R) {
265     if constexpr (std::is_signed_v<T>) {
266       return llvm::MulOverflow<T>(A, B, R);
267     } else {
268       R = A * B;
269       return false;
270     }
271   }
272   template <typename T, T Min, T Max> static bool CheckRange(int64_t V) {
273     if constexpr (std::is_signed_v<T>) {
274       return Min <= V && V <= Max;
275     } else {
276       return V >= 0 && static_cast<uint64_t>(V) <= Max;
277     }
278   }
279 };
280 
281 template <unsigned Bits, bool Signed>
282 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, Integral<Bits, Signed> I) {
283   I.print(OS);
284   return OS;
285 }
286 
287 } // namespace interp
288 } // namespace clang
289 
290 #endif
291