1 //===-- lib/Evaluate/fold-logical.cpp -------------------------------------===//
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 #include "fold-implementation.h"
10 #include "fold-reduction.h"
11 #include "flang/Evaluate/check-expression.h"
12 
13 namespace Fortran::evaluate {
14 
15 template <typename T>
ZeroExtend(const Constant<T> & c)16 static std::optional<Expr<SomeType>> ZeroExtend(const Constant<T> &c) {
17   std::vector<Scalar<LargestInt>> exts;
18   for (const auto &v : c.values()) {
19     exts.push_back(Scalar<LargestInt>::ConvertUnsigned(v).value);
20   }
21   return AsGenericExpr(
22       Constant<LargestInt>(std::move(exts), ConstantSubscripts(c.shape())));
23 }
24 
25 // for ALL & ANY
26 template <typename T>
FoldAllAny(FoldingContext & context,FunctionRef<T> && ref,Scalar<T> (Scalar<T>::* operation)(const Scalar<T> &)const,Scalar<T> identity)27 static Expr<T> FoldAllAny(FoldingContext &context, FunctionRef<T> &&ref,
28     Scalar<T> (Scalar<T>::*operation)(const Scalar<T> &) const,
29     Scalar<T> identity) {
30   static_assert(T::category == TypeCategory::Logical);
31   using Element = Scalar<T>;
32   std::optional<int> dim;
33   if (std::optional<Constant<T>> array{
34           ProcessReductionArgs<T>(context, ref.arguments(), dim, identity,
35               /*ARRAY(MASK)=*/0, /*DIM=*/1)}) {
36     auto accumulator{[&](Element &element, const ConstantSubscripts &at) {
37       element = (element.*operation)(array->At(at));
38     }};
39     return Expr<T>{DoReduction<T>(*array, dim, identity, accumulator)};
40   }
41   return Expr<T>{std::move(ref)};
42 }
43 
44 template <int KIND>
FoldIntrinsicFunction(FoldingContext & context,FunctionRef<Type<TypeCategory::Logical,KIND>> && funcRef)45 Expr<Type<TypeCategory::Logical, KIND>> FoldIntrinsicFunction(
46     FoldingContext &context,
47     FunctionRef<Type<TypeCategory::Logical, KIND>> &&funcRef) {
48   using T = Type<TypeCategory::Logical, KIND>;
49   ActualArguments &args{funcRef.arguments()};
50   auto *intrinsic{std::get_if<SpecificIntrinsic>(&funcRef.proc().u)};
51   CHECK(intrinsic);
52   std::string name{intrinsic->name};
53   using SameInt = Type<TypeCategory::Integer, KIND>;
54   if (name == "all") {
55     return FoldAllAny(
56         context, std::move(funcRef), &Scalar<T>::AND, Scalar<T>{true});
57   } else if (name == "any") {
58     return FoldAllAny(
59         context, std::move(funcRef), &Scalar<T>::OR, Scalar<T>{false});
60   } else if (name == "associated") {
61     bool gotConstant{true};
62     const Expr<SomeType> *firstArgExpr{args[0]->UnwrapExpr()};
63     if (!firstArgExpr || !IsNullPointer(*firstArgExpr)) {
64       gotConstant = false;
65     } else if (args[1]) { // There's a second argument
66       const Expr<SomeType> *secondArgExpr{args[1]->UnwrapExpr()};
67       if (!secondArgExpr || !IsNullPointer(*secondArgExpr)) {
68         gotConstant = false;
69       }
70     }
71     return gotConstant ? Expr<T>{false} : Expr<T>{std::move(funcRef)};
72   } else if (name == "bge" || name == "bgt" || name == "ble" || name == "blt") {
73     static_assert(std::is_same_v<Scalar<LargestInt>, BOZLiteralConstant>);
74 
75     // The arguments to these intrinsics can be of different types. In that
76     // case, the shorter of the two would need to be zero-extended to match
77     // the size of the other. If at least one of the operands is not a constant,
78     // the zero-extending will be done during lowering. Otherwise, the folding
79     // must be done here.
80     std::optional<Expr<SomeType>> constArgs[2];
81     for (int i{0}; i <= 1; i++) {
82       if (BOZLiteralConstant * x{UnwrapExpr<BOZLiteralConstant>(args[i])}) {
83         constArgs[i] = AsGenericExpr(Constant<LargestInt>{std::move(*x)});
84       } else if (auto *x{UnwrapExpr<Expr<SomeInteger>>(args[i])}) {
85         common::visit(
86             [&](const auto &ix) {
87               using IntT = typename std::decay_t<decltype(ix)>::Result;
88               if (auto *c{UnwrapConstantValue<IntT>(ix)}) {
89                 constArgs[i] = ZeroExtend(*c);
90               }
91             },
92             x->u);
93       }
94     }
95 
96     if (constArgs[0] && constArgs[1]) {
97       auto fptr{&Scalar<LargestInt>::BGE};
98       if (name == "bge") { // done in fptr declaration
99       } else if (name == "bgt") {
100         fptr = &Scalar<LargestInt>::BGT;
101       } else if (name == "ble") {
102         fptr = &Scalar<LargestInt>::BLE;
103       } else if (name == "blt") {
104         fptr = &Scalar<LargestInt>::BLT;
105       } else {
106         common::die("missing case to fold intrinsic function %s", name.c_str());
107       }
108 
109       for (int i{0}; i <= 1; i++) {
110         *args[i] = std::move(constArgs[i].value());
111       }
112 
113       return FoldElementalIntrinsic<T, LargestInt, LargestInt>(context,
114           std::move(funcRef),
115           ScalarFunc<T, LargestInt, LargestInt>(
116               [&fptr](
117                   const Scalar<LargestInt> &i, const Scalar<LargestInt> &j) {
118                 return Scalar<T>{std::invoke(fptr, i, j)};
119               }));
120     } else {
121       return Expr<T>{std::move(funcRef)};
122     }
123   } else if (name == "btest") {
124     if (const auto *ix{UnwrapExpr<Expr<SomeInteger>>(args[0])}) {
125       return common::visit(
126           [&](const auto &x) {
127             using IT = ResultType<decltype(x)>;
128             return FoldElementalIntrinsic<T, IT, SameInt>(context,
129                 std::move(funcRef),
130                 ScalarFunc<T, IT, SameInt>(
131                     [&](const Scalar<IT> &x, const Scalar<SameInt> &pos) {
132                       auto posVal{pos.ToInt64()};
133                       if (posVal < 0 || posVal >= x.bits) {
134                         context.messages().Say(
135                             "POS=%jd out of range for BTEST"_err_en_US,
136                             static_cast<std::intmax_t>(posVal));
137                       }
138                       return Scalar<T>{x.BTEST(posVal)};
139                     }));
140           },
141           ix->u);
142     }
143   } else if (name == "extends_type_of") {
144     // Type extension testing with EXTENDS_TYPE_OF() ignores any type
145     // parameters. Returns a constant truth value when the result is known now.
146     if (args[0] && args[1]) {
147       auto t0{args[0]->GetType()};
148       auto t1{args[1]->GetType()};
149       if (t0 && t1) {
150         if (auto result{t0->ExtendsTypeOf(*t1)}) {
151           return Expr<T>{*result};
152         }
153       }
154     }
155   } else if (name == "isnan" || name == "__builtin_ieee_is_nan") {
156     // A warning about an invalid argument is discarded from converting
157     // the argument of isnan() / IEEE_IS_NAN().
158     auto restorer{context.messages().DiscardMessages()};
159     using DefaultReal = Type<TypeCategory::Real, 4>;
160     return FoldElementalIntrinsic<T, DefaultReal>(context, std::move(funcRef),
161         ScalarFunc<T, DefaultReal>([](const Scalar<DefaultReal> &x) {
162           return Scalar<T>{x.IsNotANumber()};
163         }));
164   } else if (name == "__builtin_ieee_is_negative") {
165     auto restorer{context.messages().DiscardMessages()};
166     using DefaultReal = Type<TypeCategory::Real, 4>;
167     return FoldElementalIntrinsic<T, DefaultReal>(context, std::move(funcRef),
168         ScalarFunc<T, DefaultReal>([](const Scalar<DefaultReal> &x) {
169           return Scalar<T>{x.IsNegative()};
170         }));
171   } else if (name == "__builtin_ieee_is_normal") {
172     auto restorer{context.messages().DiscardMessages()};
173     using DefaultReal = Type<TypeCategory::Real, 4>;
174     return FoldElementalIntrinsic<T, DefaultReal>(context, std::move(funcRef),
175         ScalarFunc<T, DefaultReal>([](const Scalar<DefaultReal> &x) {
176           return Scalar<T>{x.IsNormal()};
177         }));
178   } else if (name == "is_contiguous") {
179     if (args.at(0)) {
180       if (auto *expr{args[0]->UnwrapExpr()}) {
181         if (IsSimplyContiguous(*expr, context)) {
182           return Expr<T>{true};
183         }
184       }
185     }
186   } else if (name == "lge" || name == "lgt" || name == "lle" || name == "llt") {
187     // Rewrite LGE/LGT/LLE/LLT into ASCII character relations
188     auto *cx0{UnwrapExpr<Expr<SomeCharacter>>(args[0])};
189     auto *cx1{UnwrapExpr<Expr<SomeCharacter>>(args[1])};
190     if (cx0 && cx1) {
191       return Fold(context,
192           ConvertToType<T>(
193               PackageRelation(name == "lge" ? RelationalOperator::GE
194                       : name == "lgt"       ? RelationalOperator::GT
195                       : name == "lle"       ? RelationalOperator::LE
196                                             : RelationalOperator::LT,
197                   ConvertToType<Ascii>(std::move(*cx0)),
198                   ConvertToType<Ascii>(std::move(*cx1)))));
199     }
200   } else if (name == "logical") {
201     if (auto *expr{UnwrapExpr<Expr<SomeLogical>>(args[0])}) {
202       return Fold(context, ConvertToType<T>(std::move(*expr)));
203     }
204   } else if (name == "merge") {
205     return FoldMerge<T>(context, std::move(funcRef));
206   } else if (name == "same_type_as") {
207     // Type equality testing with SAME_TYPE_AS() ignores any type parameters.
208     // Returns a constant truth value when the result is known now.
209     if (args[0] && args[1]) {
210       auto t0{args[0]->GetType()};
211       auto t1{args[1]->GetType()};
212       if (t0 && t1) {
213         if (auto result{t0->SameTypeAs(*t1)}) {
214           return Expr<T>{*result};
215         }
216       }
217     }
218   } else if (name == "__builtin_ieee_support_datatype" ||
219       name == "__builtin_ieee_support_denormal" ||
220       name == "__builtin_ieee_support_divide" ||
221       name == "__builtin_ieee_support_divide" ||
222       name == "__builtin_ieee_support_inf" ||
223       name == "__builtin_ieee_support_io" ||
224       name == "__builtin_ieee_support_nan" ||
225       name == "__builtin_ieee_support_sqrt" ||
226       name == "__builtin_ieee_support_standard" ||
227       name == "__builtin_ieee_support_subnormal" ||
228       name == "__builtin_ieee_support_underflow_control") {
229     return Expr<T>{true};
230   }
231   // TODO: dot_product, is_iostat_end,
232   // is_iostat_eor, logical, matmul, out_of_range,
233   // parity
234   return Expr<T>{std::move(funcRef)};
235 }
236 
237 template <typename T>
FoldOperation(FoldingContext & context,Relational<T> && relation)238 Expr<LogicalResult> FoldOperation(
239     FoldingContext &context, Relational<T> &&relation) {
240   if (auto array{ApplyElementwise(context, relation,
241           std::function<Expr<LogicalResult>(Expr<T> &&, Expr<T> &&)>{
242               [=](Expr<T> &&x, Expr<T> &&y) {
243                 return Expr<LogicalResult>{Relational<SomeType>{
244                     Relational<T>{relation.opr, std::move(x), std::move(y)}}};
245               }})}) {
246     return *array;
247   }
248   if (auto folded{OperandsAreConstants(relation)}) {
249     bool result{};
250     if constexpr (T::category == TypeCategory::Integer) {
251       result =
252           Satisfies(relation.opr, folded->first.CompareSigned(folded->second));
253     } else if constexpr (T::category == TypeCategory::Real) {
254       result = Satisfies(relation.opr, folded->first.Compare(folded->second));
255     } else if constexpr (T::category == TypeCategory::Complex) {
256       result = (relation.opr == RelationalOperator::EQ) ==
257           folded->first.Equals(folded->second);
258     } else if constexpr (T::category == TypeCategory::Character) {
259       result = Satisfies(relation.opr, Compare(folded->first, folded->second));
260     } else {
261       static_assert(T::category != TypeCategory::Logical);
262     }
263     return Expr<LogicalResult>{Constant<LogicalResult>{result}};
264   }
265   return Expr<LogicalResult>{Relational<SomeType>{std::move(relation)}};
266 }
267 
FoldOperation(FoldingContext & context,Relational<SomeType> && relation)268 Expr<LogicalResult> FoldOperation(
269     FoldingContext &context, Relational<SomeType> &&relation) {
270   return common::visit(
271       [&](auto &&x) {
272         return Expr<LogicalResult>{FoldOperation(context, std::move(x))};
273       },
274       std::move(relation.u));
275 }
276 
277 template <int KIND>
FoldOperation(FoldingContext & context,Not<KIND> && x)278 Expr<Type<TypeCategory::Logical, KIND>> FoldOperation(
279     FoldingContext &context, Not<KIND> &&x) {
280   if (auto array{ApplyElementwise(context, x)}) {
281     return *array;
282   }
283   using Ty = Type<TypeCategory::Logical, KIND>;
284   auto &operand{x.left()};
285   if (auto value{GetScalarConstantValue<Ty>(operand)}) {
286     return Expr<Ty>{Constant<Ty>{!value->IsTrue()}};
287   }
288   return Expr<Ty>{x};
289 }
290 
291 template <int KIND>
FoldOperation(FoldingContext & context,LogicalOperation<KIND> && operation)292 Expr<Type<TypeCategory::Logical, KIND>> FoldOperation(
293     FoldingContext &context, LogicalOperation<KIND> &&operation) {
294   using LOGICAL = Type<TypeCategory::Logical, KIND>;
295   if (auto array{ApplyElementwise(context, operation,
296           std::function<Expr<LOGICAL>(Expr<LOGICAL> &&, Expr<LOGICAL> &&)>{
297               [=](Expr<LOGICAL> &&x, Expr<LOGICAL> &&y) {
298                 return Expr<LOGICAL>{LogicalOperation<KIND>{
299                     operation.logicalOperator, std::move(x), std::move(y)}};
300               }})}) {
301     return *array;
302   }
303   if (auto folded{OperandsAreConstants(operation)}) {
304     bool xt{folded->first.IsTrue()}, yt{folded->second.IsTrue()}, result{};
305     switch (operation.logicalOperator) {
306     case LogicalOperator::And:
307       result = xt && yt;
308       break;
309     case LogicalOperator::Or:
310       result = xt || yt;
311       break;
312     case LogicalOperator::Eqv:
313       result = xt == yt;
314       break;
315     case LogicalOperator::Neqv:
316       result = xt != yt;
317       break;
318     case LogicalOperator::Not:
319       DIE("not a binary operator");
320     }
321     return Expr<LOGICAL>{Constant<LOGICAL>{result}};
322   }
323   return Expr<LOGICAL>{std::move(operation)};
324 }
325 
326 #ifdef _MSC_VER // disable bogus warning about missing definitions
327 #pragma warning(disable : 4661)
328 #endif
329 FOR_EACH_LOGICAL_KIND(template class ExpressionBase, )
330 template class ExpressionBase<SomeLogical>;
331 } // namespace Fortran::evaluate
332