1 //===-- FIRBuilder.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 "flang/Optimizer/Builder/FIRBuilder.h"
10 #include "flang/Lower/Todo.h"
11 #include "flang/Optimizer/Builder/BoxValue.h"
12 #include "flang/Optimizer/Builder/Character.h"
13 #include "flang/Optimizer/Builder/Complex.h"
14 #include "flang/Optimizer/Builder/MutableBox.h"
15 #include "flang/Optimizer/Builder/Runtime/Assign.h"
16 #include "flang/Optimizer/Dialect/FIRAttr.h"
17 #include "flang/Optimizer/Dialect/FIROpsSupport.h"
18 #include "flang/Optimizer/Support/FatalError.h"
19 #include "flang/Optimizer/Support/InternalNames.h"
20 #include "mlir/Dialect/OpenMP/OpenMPDialect.h"
21 #include "llvm/ADT/ArrayRef.h"
22 #include "llvm/ADT/StringExtras.h"
23 #include "llvm/Support/CommandLine.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/MD5.h"
26 
27 static constexpr std::size_t nameLengthHashSize = 32;
28 
29 mlir::FuncOp fir::FirOpBuilder::createFunction(mlir::Location loc,
30                                                mlir::ModuleOp module,
31                                                llvm::StringRef name,
32                                                mlir::FunctionType ty) {
33   return fir::createFuncOp(loc, module, name, ty);
34 }
35 
36 mlir::FuncOp fir::FirOpBuilder::getNamedFunction(mlir::ModuleOp modOp,
37                                                  llvm::StringRef name) {
38   return modOp.lookupSymbol<mlir::FuncOp>(name);
39 }
40 
41 mlir::FuncOp fir::FirOpBuilder::getNamedFunction(mlir::ModuleOp modOp,
42                                                  mlir::SymbolRefAttr symbol) {
43   return modOp.lookupSymbol<mlir::FuncOp>(symbol);
44 }
45 
46 fir::GlobalOp fir::FirOpBuilder::getNamedGlobal(mlir::ModuleOp modOp,
47                                                 llvm::StringRef name) {
48   return modOp.lookupSymbol<fir::GlobalOp>(name);
49 }
50 
51 mlir::Type fir::FirOpBuilder::getRefType(mlir::Type eleTy) {
52   assert(!eleTy.isa<fir::ReferenceType>() && "cannot be a reference type");
53   return fir::ReferenceType::get(eleTy);
54 }
55 
56 mlir::Type fir::FirOpBuilder::getVarLenSeqTy(mlir::Type eleTy, unsigned rank) {
57   fir::SequenceType::Shape shape(rank, fir::SequenceType::getUnknownExtent());
58   return fir::SequenceType::get(shape, eleTy);
59 }
60 
61 mlir::Type fir::FirOpBuilder::getRealType(int kind) {
62   switch (kindMap.getRealTypeID(kind)) {
63   case llvm::Type::TypeID::HalfTyID:
64     return mlir::FloatType::getF16(getContext());
65   case llvm::Type::TypeID::FloatTyID:
66     return mlir::FloatType::getF32(getContext());
67   case llvm::Type::TypeID::DoubleTyID:
68     return mlir::FloatType::getF64(getContext());
69   case llvm::Type::TypeID::X86_FP80TyID:
70     return mlir::FloatType::getF80(getContext());
71   case llvm::Type::TypeID::FP128TyID:
72     return mlir::FloatType::getF128(getContext());
73   default:
74     fir::emitFatalError(UnknownLoc::get(getContext()),
75                         "unsupported type !fir.real<kind>");
76   }
77 }
78 
79 mlir::Value fir::FirOpBuilder::createNullConstant(mlir::Location loc,
80                                                   mlir::Type ptrType) {
81   auto ty = ptrType ? ptrType : getRefType(getNoneType());
82   return create<fir::ZeroOp>(loc, ty);
83 }
84 
85 mlir::Value fir::FirOpBuilder::createIntegerConstant(mlir::Location loc,
86                                                      mlir::Type ty,
87                                                      std::int64_t cst) {
88   return create<mlir::arith::ConstantOp>(loc, ty, getIntegerAttr(ty, cst));
89 }
90 
91 mlir::Value
92 fir::FirOpBuilder::createRealConstant(mlir::Location loc, mlir::Type fltTy,
93                                       llvm::APFloat::integerPart val) {
94   auto apf = [&]() -> llvm::APFloat {
95     if (auto ty = fltTy.dyn_cast<fir::RealType>())
96       return llvm::APFloat(kindMap.getFloatSemantics(ty.getFKind()), val);
97     if (fltTy.isF16())
98       return llvm::APFloat(llvm::APFloat::IEEEhalf(), val);
99     if (fltTy.isBF16())
100       return llvm::APFloat(llvm::APFloat::BFloat(), val);
101     if (fltTy.isF32())
102       return llvm::APFloat(llvm::APFloat::IEEEsingle(), val);
103     if (fltTy.isF64())
104       return llvm::APFloat(llvm::APFloat::IEEEdouble(), val);
105     if (fltTy.isF80())
106       return llvm::APFloat(llvm::APFloat::x87DoubleExtended(), val);
107     if (fltTy.isF128())
108       return llvm::APFloat(llvm::APFloat::IEEEquad(), val);
109     llvm_unreachable("unhandled MLIR floating-point type");
110   };
111   return createRealConstant(loc, fltTy, apf());
112 }
113 
114 mlir::Value fir::FirOpBuilder::createRealConstant(mlir::Location loc,
115                                                   mlir::Type fltTy,
116                                                   const llvm::APFloat &value) {
117   if (fltTy.isa<mlir::FloatType>()) {
118     auto attr = getFloatAttr(fltTy, value);
119     return create<mlir::arith::ConstantOp>(loc, fltTy, attr);
120   }
121   llvm_unreachable("should use builtin floating-point type");
122 }
123 
124 static llvm::SmallVector<mlir::Value>
125 elideExtentsAlreadyInType(mlir::Type type, mlir::ValueRange shape) {
126   auto arrTy = type.dyn_cast<fir::SequenceType>();
127   if (shape.empty() || !arrTy)
128     return {};
129   // elide the constant dimensions before construction
130   assert(shape.size() == arrTy.getDimension());
131   llvm::SmallVector<mlir::Value> dynamicShape;
132   auto typeShape = arrTy.getShape();
133   for (unsigned i = 0, end = arrTy.getDimension(); i < end; ++i)
134     if (typeShape[i] == fir::SequenceType::getUnknownExtent())
135       dynamicShape.push_back(shape[i]);
136   return dynamicShape;
137 }
138 
139 static llvm::SmallVector<mlir::Value>
140 elideLengthsAlreadyInType(mlir::Type type, mlir::ValueRange lenParams) {
141   if (lenParams.empty())
142     return {};
143   if (auto arrTy = type.dyn_cast<fir::SequenceType>())
144     type = arrTy.getEleTy();
145   if (fir::hasDynamicSize(type))
146     return lenParams;
147   return {};
148 }
149 
150 /// Allocate a local variable.
151 /// A local variable ought to have a name in the source code.
152 mlir::Value fir::FirOpBuilder::allocateLocal(
153     mlir::Location loc, mlir::Type ty, llvm::StringRef uniqName,
154     llvm::StringRef name, bool pinned, llvm::ArrayRef<mlir::Value> shape,
155     llvm::ArrayRef<mlir::Value> lenParams, bool asTarget) {
156   // Convert the shape extents to `index`, as needed.
157   llvm::SmallVector<mlir::Value> indices;
158   llvm::SmallVector<mlir::Value> elidedShape =
159       elideExtentsAlreadyInType(ty, shape);
160   llvm::SmallVector<mlir::Value> elidedLenParams =
161       elideLengthsAlreadyInType(ty, lenParams);
162   auto idxTy = getIndexType();
163   llvm::for_each(elidedShape, [&](mlir::Value sh) {
164     indices.push_back(createConvert(loc, idxTy, sh));
165   });
166   // Add a target attribute, if needed.
167   llvm::SmallVector<mlir::NamedAttribute> attrs;
168   if (asTarget)
169     attrs.emplace_back(
170         mlir::StringAttr::get(getContext(), fir::getTargetAttrName()),
171         getUnitAttr());
172   // Create the local variable.
173   if (name.empty()) {
174     if (uniqName.empty())
175       return create<fir::AllocaOp>(loc, ty, pinned, elidedLenParams, indices,
176                                    attrs);
177     return create<fir::AllocaOp>(loc, ty, uniqName, pinned, elidedLenParams,
178                                  indices, attrs);
179   }
180   return create<fir::AllocaOp>(loc, ty, uniqName, name, pinned, elidedLenParams,
181                                indices, attrs);
182 }
183 
184 mlir::Value fir::FirOpBuilder::allocateLocal(
185     mlir::Location loc, mlir::Type ty, llvm::StringRef uniqName,
186     llvm::StringRef name, llvm::ArrayRef<mlir::Value> shape,
187     llvm::ArrayRef<mlir::Value> lenParams, bool asTarget) {
188   return allocateLocal(loc, ty, uniqName, name, /*pinned=*/false, shape,
189                        lenParams, asTarget);
190 }
191 
192 /// Get the block for adding Allocas.
193 mlir::Block *fir::FirOpBuilder::getAllocaBlock() {
194   // auto iface =
195   //     getRegion().getParentOfType<mlir::omp::OutlineableOpenMPOpInterface>();
196   // return iface ? iface.getAllocaBlock() : getEntryBlock();
197   return getEntryBlock();
198 }
199 
200 /// Create a temporary variable on the stack. Anonymous temporaries have no
201 /// `name` value. Temporaries do not require a uniqued name.
202 mlir::Value
203 fir::FirOpBuilder::createTemporary(mlir::Location loc, mlir::Type type,
204                                    llvm::StringRef name, mlir::ValueRange shape,
205                                    mlir::ValueRange lenParams,
206                                    llvm::ArrayRef<mlir::NamedAttribute> attrs) {
207   llvm::SmallVector<mlir::Value> dynamicShape =
208       elideExtentsAlreadyInType(type, shape);
209   llvm::SmallVector<mlir::Value> dynamicLength =
210       elideLengthsAlreadyInType(type, lenParams);
211   InsertPoint insPt;
212   const bool hoistAlloc = dynamicShape.empty() && dynamicLength.empty();
213   if (hoistAlloc) {
214     insPt = saveInsertionPoint();
215     setInsertionPointToStart(getAllocaBlock());
216   }
217 
218   // If the alloca is inside an OpenMP Op which will be outlined then pin the
219   // alloca here.
220   const bool pinned =
221       getRegion().getParentOfType<mlir::omp::OutlineableOpenMPOpInterface>();
222   assert(!type.isa<fir::ReferenceType>() && "cannot be a reference");
223   auto ae =
224       create<fir::AllocaOp>(loc, type, /*unique_name=*/llvm::StringRef{}, name,
225                             pinned, dynamicLength, dynamicShape, attrs);
226   if (hoistAlloc)
227     restoreInsertionPoint(insPt);
228   return ae;
229 }
230 
231 /// Create a global variable in the (read-only) data section. A global variable
232 /// must have a unique name to identify and reference it.
233 fir::GlobalOp
234 fir::FirOpBuilder::createGlobal(mlir::Location loc, mlir::Type type,
235                                 llvm::StringRef name, mlir::StringAttr linkage,
236                                 mlir::Attribute value, bool isConst) {
237   auto module = getModule();
238   auto insertPt = saveInsertionPoint();
239   if (auto glob = module.lookupSymbol<fir::GlobalOp>(name))
240     return glob;
241   setInsertionPoint(module.getBody(), module.getBody()->end());
242   auto glob = create<fir::GlobalOp>(loc, name, isConst, type, value, linkage);
243   restoreInsertionPoint(insertPt);
244   return glob;
245 }
246 
247 fir::GlobalOp fir::FirOpBuilder::createGlobal(
248     mlir::Location loc, mlir::Type type, llvm::StringRef name, bool isConst,
249     std::function<void(FirOpBuilder &)> bodyBuilder, mlir::StringAttr linkage) {
250   auto module = getModule();
251   auto insertPt = saveInsertionPoint();
252   if (auto glob = module.lookupSymbol<fir::GlobalOp>(name))
253     return glob;
254   setInsertionPoint(module.getBody(), module.getBody()->end());
255   auto glob = create<fir::GlobalOp>(loc, name, isConst, type, mlir::Attribute{},
256                                     linkage);
257   auto &region = glob.getRegion();
258   region.push_back(new mlir::Block);
259   auto &block = glob.getRegion().back();
260   setInsertionPointToStart(&block);
261   bodyBuilder(*this);
262   restoreInsertionPoint(insertPt);
263   return glob;
264 }
265 
266 mlir::Value
267 fir::FirOpBuilder::convertWithSemantics(mlir::Location loc, mlir::Type toTy,
268                                         mlir::Value val,
269                                         bool allowCharacterConversion) {
270   assert(toTy && "store location must be typed");
271   auto fromTy = val.getType();
272   if (fromTy == toTy)
273     return val;
274   fir::factory::Complex helper{*this, loc};
275   if ((fir::isa_real(fromTy) || fir::isa_integer(fromTy)) &&
276       fir::isa_complex(toTy)) {
277     // imaginary part is zero
278     auto eleTy = helper.getComplexPartType(toTy);
279     auto cast = createConvert(loc, eleTy, val);
280     llvm::APFloat zero{
281         kindMap.getFloatSemantics(toTy.cast<fir::ComplexType>().getFKind()), 0};
282     auto imag = createRealConstant(loc, eleTy, zero);
283     return helper.createComplex(toTy, cast, imag);
284   }
285   if (fir::isa_complex(fromTy) &&
286       (fir::isa_integer(toTy) || fir::isa_real(toTy))) {
287     // drop the imaginary part
288     auto rp = helper.extractComplexPart(val, /*isImagPart=*/false);
289     return createConvert(loc, toTy, rp);
290   }
291   if (allowCharacterConversion) {
292     if (fromTy.isa<fir::BoxCharType>()) {
293       // Extract the address of the character string and pass it
294       fir::factory::CharacterExprHelper charHelper{*this, loc};
295       std::pair<mlir::Value, mlir::Value> unboxchar =
296           charHelper.createUnboxChar(val);
297       return createConvert(loc, toTy, unboxchar.first);
298     }
299     if (auto boxType = toTy.dyn_cast<fir::BoxCharType>()) {
300       // Extract the address of the actual argument and create a boxed
301       // character value with an undefined length
302       // TODO: We should really calculate the total size of the actual
303       // argument in characters and use it as the length of the string
304       auto refType = getRefType(boxType.getEleTy());
305       mlir::Value charBase = createConvert(loc, refType, val);
306       mlir::Value unknownLen = create<fir::UndefOp>(loc, getIndexType());
307       fir::factory::CharacterExprHelper charHelper{*this, loc};
308       return charHelper.createEmboxChar(charBase, unknownLen);
309     }
310   }
311   if (fir::isa_ref_type(toTy) && fir::isa_box_type(fromTy)) {
312     // Call is expecting a raw data pointer, not a box. Get the data pointer out
313     // of the box and pass that.
314     assert((fir::unwrapRefType(toTy) ==
315                 fir::unwrapRefType(fir::unwrapPassByRefType(fromTy)) &&
316             "element types expected to match"));
317     return create<fir::BoxAddrOp>(loc, toTy, val);
318   }
319 
320   return createConvert(loc, toTy, val);
321 }
322 
323 mlir::Value fir::FirOpBuilder::createConvert(mlir::Location loc,
324                                              mlir::Type toTy, mlir::Value val) {
325   if (val.getType() != toTy) {
326     assert(!fir::isa_derived(toTy));
327     return create<fir::ConvertOp>(loc, toTy, val);
328   }
329   return val;
330 }
331 
332 fir::StringLitOp fir::FirOpBuilder::createStringLitOp(mlir::Location loc,
333                                                       llvm::StringRef data) {
334   auto type = fir::CharacterType::get(getContext(), 1, data.size());
335   auto strAttr = mlir::StringAttr::get(getContext(), data);
336   auto valTag = mlir::StringAttr::get(getContext(), fir::StringLitOp::value());
337   mlir::NamedAttribute dataAttr(valTag, strAttr);
338   auto sizeTag = mlir::StringAttr::get(getContext(), fir::StringLitOp::size());
339   mlir::NamedAttribute sizeAttr(sizeTag, getI64IntegerAttr(data.size()));
340   llvm::SmallVector<mlir::NamedAttribute> attrs{dataAttr, sizeAttr};
341   return create<fir::StringLitOp>(loc, llvm::ArrayRef<mlir::Type>{type},
342                                   llvm::None, attrs);
343 }
344 
345 mlir::Value fir::FirOpBuilder::genShape(mlir::Location loc,
346                                         llvm::ArrayRef<mlir::Value> exts) {
347   auto shapeType = fir::ShapeType::get(getContext(), exts.size());
348   return create<fir::ShapeOp>(loc, shapeType, exts);
349 }
350 
351 mlir::Value fir::FirOpBuilder::genShape(mlir::Location loc,
352                                         llvm::ArrayRef<mlir::Value> shift,
353                                         llvm::ArrayRef<mlir::Value> exts) {
354   auto shapeType = fir::ShapeShiftType::get(getContext(), exts.size());
355   llvm::SmallVector<mlir::Value> shapeArgs;
356   auto idxTy = getIndexType();
357   for (auto [lbnd, ext] : llvm::zip(shift, exts)) {
358     auto lb = createConvert(loc, idxTy, lbnd);
359     shapeArgs.push_back(lb);
360     shapeArgs.push_back(ext);
361   }
362   return create<fir::ShapeShiftOp>(loc, shapeType, shapeArgs);
363 }
364 
365 mlir::Value fir::FirOpBuilder::genShape(mlir::Location loc,
366                                         const fir::AbstractArrayBox &arr) {
367   if (arr.lboundsAllOne())
368     return genShape(loc, arr.getExtents());
369   return genShape(loc, arr.getLBounds(), arr.getExtents());
370 }
371 
372 mlir::Value fir::FirOpBuilder::createShape(mlir::Location loc,
373                                            const fir::ExtendedValue &exv) {
374   return exv.match(
375       [&](const fir::ArrayBoxValue &box) { return genShape(loc, box); },
376       [&](const fir::CharArrayBoxValue &box) { return genShape(loc, box); },
377       [&](const fir::BoxValue &box) -> mlir::Value {
378         if (!box.getLBounds().empty()) {
379           auto shiftType =
380               fir::ShiftType::get(getContext(), box.getLBounds().size());
381           return create<fir::ShiftOp>(loc, shiftType, box.getLBounds());
382         }
383         return {};
384       },
385       [&](const fir::MutableBoxValue &) -> mlir::Value {
386         // MutableBoxValue must be read into another category to work with them
387         // outside of allocation/assignment contexts.
388         fir::emitFatalError(loc, "createShape on MutableBoxValue");
389       },
390       [&](auto) -> mlir::Value { fir::emitFatalError(loc, "not an array"); });
391 }
392 
393 mlir::Value fir::FirOpBuilder::createSlice(mlir::Location loc,
394                                            const fir::ExtendedValue &exv,
395                                            mlir::ValueRange triples,
396                                            mlir::ValueRange path) {
397   if (triples.empty()) {
398     // If there is no slicing by triple notation, then take the whole array.
399     auto fullShape = [&](const llvm::ArrayRef<mlir::Value> lbounds,
400                          llvm::ArrayRef<mlir::Value> extents) -> mlir::Value {
401       llvm::SmallVector<mlir::Value> trips;
402       auto idxTy = getIndexType();
403       auto one = createIntegerConstant(loc, idxTy, 1);
404       if (lbounds.empty()) {
405         for (auto v : extents) {
406           trips.push_back(one);
407           trips.push_back(v);
408           trips.push_back(one);
409         }
410         return create<fir::SliceOp>(loc, trips, path);
411       }
412       for (auto [lbnd, extent] : llvm::zip(lbounds, extents)) {
413         auto lb = createConvert(loc, idxTy, lbnd);
414         auto ext = createConvert(loc, idxTy, extent);
415         auto shift = create<mlir::arith::SubIOp>(loc, lb, one);
416         auto ub = create<mlir::arith::AddIOp>(loc, ext, shift);
417         trips.push_back(lb);
418         trips.push_back(ub);
419         trips.push_back(one);
420       }
421       return create<fir::SliceOp>(loc, trips, path);
422     };
423     return exv.match(
424         [&](const fir::ArrayBoxValue &box) {
425           return fullShape(box.getLBounds(), box.getExtents());
426         },
427         [&](const fir::CharArrayBoxValue &box) {
428           return fullShape(box.getLBounds(), box.getExtents());
429         },
430         [&](const fir::BoxValue &box) {
431           auto extents = fir::factory::readExtents(*this, loc, box);
432           return fullShape(box.getLBounds(), extents);
433         },
434         [&](const fir::MutableBoxValue &) -> mlir::Value {
435           // MutableBoxValue must be read into another category to work with
436           // them outside of allocation/assignment contexts.
437           fir::emitFatalError(loc, "createSlice on MutableBoxValue");
438         },
439         [&](auto) -> mlir::Value { fir::emitFatalError(loc, "not an array"); });
440   }
441   return create<fir::SliceOp>(loc, triples, path);
442 }
443 
444 mlir::Value fir::FirOpBuilder::createBox(mlir::Location loc,
445                                          const fir::ExtendedValue &exv) {
446   mlir::Value itemAddr = fir::getBase(exv);
447   if (itemAddr.getType().isa<fir::BoxType>())
448     return itemAddr;
449   auto elementType = fir::dyn_cast_ptrEleTy(itemAddr.getType());
450   if (!elementType) {
451     mlir::emitError(loc, "internal: expected a memory reference type ")
452         << itemAddr.getType();
453     llvm_unreachable("not a memory reference type");
454   }
455   mlir::Type boxTy = fir::BoxType::get(elementType);
456   return exv.match(
457       [&](const fir::ArrayBoxValue &box) -> mlir::Value {
458         mlir::Value s = createShape(loc, exv);
459         return create<fir::EmboxOp>(loc, boxTy, itemAddr, s);
460       },
461       [&](const fir::CharArrayBoxValue &box) -> mlir::Value {
462         mlir::Value s = createShape(loc, exv);
463         if (fir::factory::CharacterExprHelper::hasConstantLengthInType(exv))
464           return create<fir::EmboxOp>(loc, boxTy, itemAddr, s);
465 
466         mlir::Value emptySlice;
467         llvm::SmallVector<mlir::Value> lenParams{box.getLen()};
468         return create<fir::EmboxOp>(loc, boxTy, itemAddr, s, emptySlice,
469                                     lenParams);
470       },
471       [&](const fir::CharBoxValue &box) -> mlir::Value {
472         if (fir::factory::CharacterExprHelper::hasConstantLengthInType(exv))
473           return create<fir::EmboxOp>(loc, boxTy, itemAddr);
474         mlir::Value emptyShape, emptySlice;
475         llvm::SmallVector<mlir::Value> lenParams{box.getLen()};
476         return create<fir::EmboxOp>(loc, boxTy, itemAddr, emptyShape,
477                                     emptySlice, lenParams);
478       },
479       [&](const fir::MutableBoxValue &x) -> mlir::Value {
480         return create<fir::LoadOp>(
481             loc, fir::factory::getMutableIRBox(*this, loc, x));
482       },
483       // UnboxedValue, ProcBoxValue or BoxValue.
484       [&](const auto &) -> mlir::Value {
485         return create<fir::EmboxOp>(loc, boxTy, itemAddr);
486       });
487 }
488 
489 static mlir::Value
490 genNullPointerComparison(fir::FirOpBuilder &builder, mlir::Location loc,
491                          mlir::Value addr,
492                          mlir::arith::CmpIPredicate condition) {
493   auto intPtrTy = builder.getIntPtrType();
494   auto ptrToInt = builder.createConvert(loc, intPtrTy, addr);
495   auto c0 = builder.createIntegerConstant(loc, intPtrTy, 0);
496   return builder.create<mlir::arith::CmpIOp>(loc, condition, ptrToInt, c0);
497 }
498 
499 mlir::Value fir::FirOpBuilder::genIsNotNull(mlir::Location loc,
500                                             mlir::Value addr) {
501   return genNullPointerComparison(*this, loc, addr,
502                                   mlir::arith::CmpIPredicate::ne);
503 }
504 
505 mlir::Value fir::FirOpBuilder::genIsNull(mlir::Location loc, mlir::Value addr) {
506   return genNullPointerComparison(*this, loc, addr,
507                                   mlir::arith::CmpIPredicate::eq);
508 }
509 
510 //===--------------------------------------------------------------------===//
511 // ExtendedValue inquiry helper implementation
512 //===--------------------------------------------------------------------===//
513 
514 mlir::Value fir::factory::readCharLen(fir::FirOpBuilder &builder,
515                                       mlir::Location loc,
516                                       const fir::ExtendedValue &box) {
517   return box.match(
518       [&](const fir::CharBoxValue &x) -> mlir::Value { return x.getLen(); },
519       [&](const fir::CharArrayBoxValue &x) -> mlir::Value {
520         return x.getLen();
521       },
522       [&](const fir::BoxValue &x) -> mlir::Value {
523         assert(x.isCharacter());
524         if (!x.getExplicitParameters().empty())
525           return x.getExplicitParameters()[0];
526         return fir::factory::CharacterExprHelper{builder, loc}
527             .readLengthFromBox(x.getAddr());
528       },
529       [&](const fir::MutableBoxValue &) -> mlir::Value {
530         // MutableBoxValue must be read into another category to work with them
531         // outside of allocation/assignment contexts.
532         fir::emitFatalError(loc, "readCharLen on MutableBoxValue");
533       },
534       [&](const auto &) -> mlir::Value {
535         fir::emitFatalError(
536             loc, "Character length inquiry on a non-character entity");
537       });
538 }
539 
540 mlir::Value fir::factory::readExtent(fir::FirOpBuilder &builder,
541                                      mlir::Location loc,
542                                      const fir::ExtendedValue &box,
543                                      unsigned dim) {
544   assert(box.rank() > dim);
545   return box.match(
546       [&](const fir::ArrayBoxValue &x) -> mlir::Value {
547         return x.getExtents()[dim];
548       },
549       [&](const fir::CharArrayBoxValue &x) -> mlir::Value {
550         return x.getExtents()[dim];
551       },
552       [&](const fir::BoxValue &x) -> mlir::Value {
553         if (!x.getExplicitExtents().empty())
554           return x.getExplicitExtents()[dim];
555         auto idxTy = builder.getIndexType();
556         auto dimVal = builder.createIntegerConstant(loc, idxTy, dim);
557         return builder
558             .create<fir::BoxDimsOp>(loc, idxTy, idxTy, idxTy, x.getAddr(),
559                                     dimVal)
560             .getResult(1);
561       },
562       [&](const fir::MutableBoxValue &x) -> mlir::Value {
563         // MutableBoxValue must be read into another category to work with them
564         // outside of allocation/assignment contexts.
565         fir::emitFatalError(loc, "readExtents on MutableBoxValue");
566       },
567       [&](const auto &) -> mlir::Value {
568         fir::emitFatalError(loc, "extent inquiry on scalar");
569       });
570 }
571 
572 mlir::Value fir::factory::readLowerBound(fir::FirOpBuilder &builder,
573                                          mlir::Location loc,
574                                          const fir::ExtendedValue &box,
575                                          unsigned dim,
576                                          mlir::Value defaultValue) {
577   assert(box.rank() > dim);
578   auto lb = box.match(
579       [&](const fir::ArrayBoxValue &x) -> mlir::Value {
580         return x.getLBounds().empty() ? mlir::Value{} : x.getLBounds()[dim];
581       },
582       [&](const fir::CharArrayBoxValue &x) -> mlir::Value {
583         return x.getLBounds().empty() ? mlir::Value{} : x.getLBounds()[dim];
584       },
585       [&](const fir::BoxValue &x) -> mlir::Value {
586         return x.getLBounds().empty() ? mlir::Value{} : x.getLBounds()[dim];
587       },
588       [&](const fir::MutableBoxValue &x) -> mlir::Value {
589         return readLowerBound(builder, loc,
590                               fir::factory::genMutableBoxRead(builder, loc, x),
591                               dim, defaultValue);
592       },
593       [&](const auto &) -> mlir::Value {
594         fir::emitFatalError(loc, "lower bound inquiry on scalar");
595       });
596   if (lb)
597     return lb;
598   return defaultValue;
599 }
600 
601 llvm::SmallVector<mlir::Value>
602 fir::factory::readExtents(fir::FirOpBuilder &builder, mlir::Location loc,
603                           const fir::BoxValue &box) {
604   llvm::SmallVector<mlir::Value> result;
605   auto explicitExtents = box.getExplicitExtents();
606   if (!explicitExtents.empty()) {
607     result.append(explicitExtents.begin(), explicitExtents.end());
608     return result;
609   }
610   auto rank = box.rank();
611   auto idxTy = builder.getIndexType();
612   for (decltype(rank) dim = 0; dim < rank; ++dim) {
613     auto dimVal = builder.createIntegerConstant(loc, idxTy, dim);
614     auto dimInfo = builder.create<fir::BoxDimsOp>(loc, idxTy, idxTy, idxTy,
615                                                   box.getAddr(), dimVal);
616     result.emplace_back(dimInfo.getResult(1));
617   }
618   return result;
619 }
620 
621 llvm::SmallVector<mlir::Value>
622 fir::factory::getExtents(fir::FirOpBuilder &builder, mlir::Location loc,
623                          const fir::ExtendedValue &box) {
624   return box.match(
625       [&](const fir::ArrayBoxValue &x) -> llvm::SmallVector<mlir::Value> {
626         return {x.getExtents().begin(), x.getExtents().end()};
627       },
628       [&](const fir::CharArrayBoxValue &x) -> llvm::SmallVector<mlir::Value> {
629         return {x.getExtents().begin(), x.getExtents().end()};
630       },
631       [&](const fir::BoxValue &x) -> llvm::SmallVector<mlir::Value> {
632         return fir::factory::readExtents(builder, loc, x);
633       },
634       [&](const fir::MutableBoxValue &x) -> llvm::SmallVector<mlir::Value> {
635         auto load = fir::factory::genMutableBoxRead(builder, loc, x);
636         return fir::factory::getExtents(builder, loc, load);
637       },
638       [&](const auto &) -> llvm::SmallVector<mlir::Value> { return {}; });
639 }
640 
641 fir::ExtendedValue fir::factory::readBoxValue(fir::FirOpBuilder &builder,
642                                               mlir::Location loc,
643                                               const fir::BoxValue &box) {
644   assert(!box.isUnlimitedPolymorphic() && !box.hasAssumedRank() &&
645          "cannot read unlimited polymorphic or assumed rank fir.box");
646   auto addr =
647       builder.create<fir::BoxAddrOp>(loc, box.getMemTy(), box.getAddr());
648   if (box.isCharacter()) {
649     auto len = fir::factory::readCharLen(builder, loc, box);
650     if (box.rank() == 0)
651       return fir::CharBoxValue(addr, len);
652     return fir::CharArrayBoxValue(addr, len,
653                                   fir::factory::readExtents(builder, loc, box),
654                                   box.getLBounds());
655   }
656   if (box.isDerivedWithLengthParameters())
657     TODO(loc, "read fir.box with length parameters");
658   if (box.rank() == 0)
659     return addr;
660   return fir::ArrayBoxValue(addr, fir::factory::readExtents(builder, loc, box),
661                             box.getLBounds());
662 }
663 
664 std::string fir::factory::uniqueCGIdent(llvm::StringRef prefix,
665                                         llvm::StringRef name) {
666   // For "long" identifiers use a hash value
667   if (name.size() > nameLengthHashSize) {
668     llvm::MD5 hash;
669     hash.update(name);
670     llvm::MD5::MD5Result result;
671     hash.final(result);
672     llvm::SmallString<32> str;
673     llvm::MD5::stringifyResult(result, str);
674     std::string hashName = prefix.str();
675     hashName.append(".").append(str.c_str());
676     return fir::NameUniquer::doGenerated(hashName);
677   }
678   // "Short" identifiers use a reversible hex string
679   std::string nm = prefix.str();
680   return fir::NameUniquer::doGenerated(
681       nm.append(".").append(llvm::toHex(name)));
682 }
683 
684 mlir::Value fir::factory::locationToFilename(fir::FirOpBuilder &builder,
685                                              mlir::Location loc) {
686   if (auto flc = loc.dyn_cast<mlir::FileLineColLoc>()) {
687     // must be encoded as asciiz, C string
688     auto fn = flc.getFilename().str() + '\0';
689     return fir::getBase(createStringLiteral(builder, loc, fn));
690   }
691   return builder.createNullConstant(loc);
692 }
693 
694 mlir::Value fir::factory::locationToLineNo(fir::FirOpBuilder &builder,
695                                            mlir::Location loc,
696                                            mlir::Type type) {
697   if (auto flc = loc.dyn_cast<mlir::FileLineColLoc>())
698     return builder.createIntegerConstant(loc, type, flc.getLine());
699   return builder.createIntegerConstant(loc, type, 0);
700 }
701 
702 fir::ExtendedValue fir::factory::createStringLiteral(fir::FirOpBuilder &builder,
703                                                      mlir::Location loc,
704                                                      llvm::StringRef str) {
705   std::string globalName = fir::factory::uniqueCGIdent("cl", str);
706   auto type = fir::CharacterType::get(builder.getContext(), 1, str.size());
707   auto global = builder.getNamedGlobal(globalName);
708   if (!global)
709     global = builder.createGlobalConstant(
710         loc, type, globalName,
711         [&](fir::FirOpBuilder &builder) {
712           auto stringLitOp = builder.createStringLitOp(loc, str);
713           builder.create<fir::HasValueOp>(loc, stringLitOp);
714         },
715         builder.createLinkOnceLinkage());
716   auto addr = builder.create<fir::AddrOfOp>(loc, global.resultType(),
717                                             global.getSymbol());
718   auto len = builder.createIntegerConstant(
719       loc, builder.getCharacterLengthType(), str.size());
720   return fir::CharBoxValue{addr, len};
721 }
722 
723 llvm::SmallVector<mlir::Value>
724 fir::factory::createExtents(fir::FirOpBuilder &builder, mlir::Location loc,
725                             fir::SequenceType seqTy) {
726   llvm::SmallVector<mlir::Value> extents;
727   auto idxTy = builder.getIndexType();
728   for (auto ext : seqTy.getShape())
729     extents.emplace_back(
730         ext == fir::SequenceType::getUnknownExtent()
731             ? builder.create<fir::UndefOp>(loc, idxTy).getResult()
732             : builder.createIntegerConstant(loc, idxTy, ext));
733   return extents;
734 }
735 
736 // FIXME: This needs some work. To correctly determine the extended value of a
737 // component, one needs the base object, its type, and its type parameters. (An
738 // alternative would be to provide an already computed address of the final
739 // component rather than the base object's address, the point being the result
740 // will require the address of the final component to create the extended
741 // value.) One further needs the full path of components being applied. One
742 // needs to apply type-based expressions to type parameters along this said
743 // path. (See applyPathToType for a type-only derivation.) Finally, one needs to
744 // compose the extended value of the terminal component, including all of its
745 // parameters: array lower bounds expressions, extents, type parameters, etc.
746 // Any of these properties may be deferred until runtime in Fortran. This
747 // operation may therefore generate a sizeable block of IR, including calls to
748 // type-based helper functions, so caching the result of this operation in the
749 // client would be advised as well.
750 fir::ExtendedValue fir::factory::componentToExtendedValue(
751     fir::FirOpBuilder &builder, mlir::Location loc, mlir::Value component) {
752   auto fieldTy = component.getType();
753   if (auto ty = fir::dyn_cast_ptrEleTy(fieldTy))
754     fieldTy = ty;
755   if (fieldTy.isa<fir::BoxType>()) {
756     llvm::SmallVector<mlir::Value> nonDeferredTypeParams;
757     auto eleTy = fir::unwrapSequenceType(fir::dyn_cast_ptrOrBoxEleTy(fieldTy));
758     if (auto charTy = eleTy.dyn_cast<fir::CharacterType>()) {
759       auto lenTy = builder.getCharacterLengthType();
760       if (charTy.hasConstantLen())
761         nonDeferredTypeParams.emplace_back(
762             builder.createIntegerConstant(loc, lenTy, charTy.getLen()));
763       // TODO: Starting, F2003, the dynamic character length might be dependent
764       // on a PDT length parameter. There is no way to make a difference with
765       // deferred length here yet.
766     }
767     if (auto recTy = eleTy.dyn_cast<fir::RecordType>())
768       if (recTy.getNumLenParams() > 0)
769         TODO(loc, "allocatable and pointer components non deferred length "
770                   "parameters");
771 
772     return fir::MutableBoxValue(component, nonDeferredTypeParams,
773                                 /*mutableProperties=*/{});
774   }
775   llvm::SmallVector<mlir::Value> extents;
776   if (auto seqTy = fieldTy.dyn_cast<fir::SequenceType>()) {
777     fieldTy = seqTy.getEleTy();
778     auto idxTy = builder.getIndexType();
779     for (auto extent : seqTy.getShape()) {
780       if (extent == fir::SequenceType::getUnknownExtent())
781         TODO(loc, "array component shape depending on length parameters");
782       extents.emplace_back(builder.createIntegerConstant(loc, idxTy, extent));
783     }
784   }
785   if (auto charTy = fieldTy.dyn_cast<fir::CharacterType>()) {
786     auto cstLen = charTy.getLen();
787     if (cstLen == fir::CharacterType::unknownLen())
788       TODO(loc, "get character component length from length type parameters");
789     auto len = builder.createIntegerConstant(
790         loc, builder.getCharacterLengthType(), cstLen);
791     if (!extents.empty())
792       return fir::CharArrayBoxValue{component, len, extents};
793     return fir::CharBoxValue{component, len};
794   }
795   if (auto recordTy = fieldTy.dyn_cast<fir::RecordType>())
796     if (recordTy.getNumLenParams() != 0)
797       TODO(loc,
798            "lower component ref that is a derived type with length parameter");
799   if (!extents.empty())
800     return fir::ArrayBoxValue{component, extents};
801   return component;
802 }
803 
804 fir::ExtendedValue fir::factory::arrayElementToExtendedValue(
805     fir::FirOpBuilder &builder, mlir::Location loc,
806     const fir::ExtendedValue &array, mlir::Value element) {
807   return array.match(
808       [&](const fir::CharBoxValue &cb) -> fir::ExtendedValue {
809         return cb.clone(element);
810       },
811       [&](const fir::CharArrayBoxValue &bv) -> fir::ExtendedValue {
812         return bv.cloneElement(element);
813       },
814       [&](const fir::BoxValue &box) -> fir::ExtendedValue {
815         if (box.isCharacter()) {
816           auto len = fir::factory::readCharLen(builder, loc, box);
817           return fir::CharBoxValue{element, len};
818         }
819         if (box.isDerivedWithLengthParameters())
820           TODO(loc, "get length parameters from derived type BoxValue");
821         return element;
822       },
823       [&](const auto &) -> fir::ExtendedValue { return element; });
824 }
825 
826 fir::ExtendedValue fir::factory::arraySectionElementToExtendedValue(
827     fir::FirOpBuilder &builder, mlir::Location loc,
828     const fir::ExtendedValue &array, mlir::Value element, mlir::Value slice) {
829   if (!slice)
830     return arrayElementToExtendedValue(builder, loc, array, element);
831   auto sliceOp = mlir::dyn_cast_or_null<fir::SliceOp>(slice.getDefiningOp());
832   assert(sliceOp && "slice must be a sliceOp");
833   if (sliceOp.getFields().empty())
834     return arrayElementToExtendedValue(builder, loc, array, element);
835   // For F95, using componentToExtendedValue will work, but when PDTs are
836   // lowered. It will be required to go down the slice to propagate the length
837   // parameters.
838   return fir::factory::componentToExtendedValue(builder, loc, element);
839 }
840 
841 mlir::TupleType
842 fir::factory::getRaggedArrayHeaderType(fir::FirOpBuilder &builder) {
843   mlir::IntegerType i64Ty = builder.getIntegerType(64);
844   auto arrTy = fir::SequenceType::get(builder.getIntegerType(8), 1);
845   auto buffTy = fir::HeapType::get(arrTy);
846   auto extTy = fir::SequenceType::get(i64Ty, 1);
847   auto shTy = fir::HeapType::get(extTy);
848   return mlir::TupleType::get(builder.getContext(), {i64Ty, buffTy, shTy});
849 }
850 
851 mlir::Value fir::factory::createZeroValue(fir::FirOpBuilder &builder,
852                                           mlir::Location loc, mlir::Type type) {
853   mlir::Type i1 = builder.getIntegerType(1);
854   if (type.isa<fir::LogicalType>() || type == i1)
855     return builder.createConvert(loc, type, builder.createBool(loc, false));
856   if (fir::isa_integer(type))
857     return builder.createIntegerConstant(loc, type, 0);
858   if (fir::isa_real(type))
859     return builder.createRealZeroConstant(loc, type);
860   if (fir::isa_complex(type)) {
861     fir::factory::Complex complexHelper(builder, loc);
862     mlir::Type partType = complexHelper.getComplexPartType(type);
863     mlir::Value zeroPart = builder.createRealZeroConstant(loc, partType);
864     return complexHelper.createComplex(type, zeroPart, zeroPart);
865   }
866   fir::emitFatalError(loc, "internal: trying to generate zero value of non "
867                            "numeric or logical type");
868 }
869 
870 void fir::factory::genScalarAssignment(fir::FirOpBuilder &builder,
871                                        mlir::Location loc,
872                                        const fir::ExtendedValue &lhs,
873                                        const fir::ExtendedValue &rhs) {
874   assert(lhs.rank() == 0 && rhs.rank() == 0 && "must be scalars");
875   auto type = fir::unwrapSequenceType(
876       fir::unwrapPassByRefType(fir::getBase(lhs).getType()));
877   if (type.isa<fir::CharacterType>()) {
878     const fir::CharBoxValue *toChar = lhs.getCharBox();
879     const fir::CharBoxValue *fromChar = rhs.getCharBox();
880     assert(toChar && fromChar);
881     fir::factory::CharacterExprHelper helper{builder, loc};
882     helper.createAssign(fir::ExtendedValue{*toChar},
883                         fir::ExtendedValue{*fromChar});
884   } else if (type.isa<fir::RecordType>()) {
885     fir::factory::genRecordAssignment(builder, loc, lhs, rhs);
886   } else {
887     assert(!fir::hasDynamicSize(type));
888     auto rhsVal = fir::getBase(rhs);
889     if (fir::isa_ref_type(rhsVal.getType()))
890       rhsVal = builder.create<fir::LoadOp>(loc, rhsVal);
891     mlir::Value lhsAddr = fir::getBase(lhs);
892     rhsVal = builder.createConvert(loc, fir::unwrapRefType(lhsAddr.getType()),
893                                    rhsVal);
894     builder.create<fir::StoreOp>(loc, rhsVal, lhsAddr);
895   }
896 }
897 
898 static void genComponentByComponentAssignment(fir::FirOpBuilder &builder,
899                                               mlir::Location loc,
900                                               const fir::ExtendedValue &lhs,
901                                               const fir::ExtendedValue &rhs) {
902   auto baseType = fir::unwrapPassByRefType(fir::getBase(lhs).getType());
903   auto lhsType = baseType.dyn_cast<fir::RecordType>();
904   assert(lhsType && "lhs must be a scalar record type");
905   auto fieldIndexType = fir::FieldType::get(lhsType.getContext());
906   for (auto [fieldName, fieldType] : lhsType.getTypeList()) {
907     assert(!fir::hasDynamicSize(fieldType));
908     mlir::Value field = builder.create<fir::FieldIndexOp>(
909         loc, fieldIndexType, fieldName, lhsType, fir::getTypeParams(lhs));
910     auto fieldRefType = builder.getRefType(fieldType);
911     mlir::Value fromCoor = builder.create<fir::CoordinateOp>(
912         loc, fieldRefType, fir::getBase(rhs), field);
913     mlir::Value toCoor = builder.create<fir::CoordinateOp>(
914         loc, fieldRefType, fir::getBase(lhs), field);
915     llvm::Optional<fir::DoLoopOp> outerLoop;
916     if (auto sequenceType = fieldType.dyn_cast<fir::SequenceType>()) {
917       // Create loops to assign array components elements by elements.
918       // Note that, since these are components, they either do not overlap,
919       // or are the same and exactly overlap. They also have compile time
920       // constant shapes.
921       mlir::Type idxTy = builder.getIndexType();
922       llvm::SmallVector<mlir::Value> indices;
923       mlir::Value zero = builder.createIntegerConstant(loc, idxTy, 0);
924       mlir::Value one = builder.createIntegerConstant(loc, idxTy, 1);
925       for (auto extent : llvm::reverse(sequenceType.getShape())) {
926         // TODO: add zero size test !
927         mlir::Value ub = builder.createIntegerConstant(loc, idxTy, extent - 1);
928         auto loop = builder.create<fir::DoLoopOp>(loc, zero, ub, one);
929         if (!outerLoop)
930           outerLoop = loop;
931         indices.push_back(loop.getInductionVar());
932         builder.setInsertionPointToStart(loop.getBody());
933       }
934       // Set indices in column-major order.
935       std::reverse(indices.begin(), indices.end());
936       auto elementRefType = builder.getRefType(sequenceType.getEleTy());
937       toCoor = builder.create<fir::CoordinateOp>(loc, elementRefType, toCoor,
938                                                  indices);
939       fromCoor = builder.create<fir::CoordinateOp>(loc, elementRefType,
940                                                    fromCoor, indices);
941     }
942     auto fieldElementType = fir::unwrapSequenceType(fieldType);
943     if (fieldElementType.isa<fir::BoxType>()) {
944       assert(fieldElementType.cast<fir::BoxType>()
945                  .getEleTy()
946                  .isa<fir::PointerType>() &&
947              "allocatable require deep copy");
948       auto fromPointerValue = builder.create<fir::LoadOp>(loc, fromCoor);
949       builder.create<fir::StoreOp>(loc, fromPointerValue, toCoor);
950     } else {
951       auto from =
952           fir::factory::componentToExtendedValue(builder, loc, fromCoor);
953       auto to = fir::factory::componentToExtendedValue(builder, loc, toCoor);
954       fir::factory::genScalarAssignment(builder, loc, to, from);
955     }
956     if (outerLoop)
957       builder.setInsertionPointAfter(*outerLoop);
958   }
959 }
960 
961 /// Can the assignment of this record type be implement with a simple memory
962 /// copy (it requires no deep copy or user defined assignment of components )?
963 static bool recordTypeCanBeMemCopied(fir::RecordType recordType) {
964   if (fir::hasDynamicSize(recordType))
965     return false;
966   for (auto [_, fieldType] : recordType.getTypeList()) {
967     // Derived type component may have user assignment (so far, we cannot tell
968     // in FIR, so assume it is always the case, TODO: get the actual info).
969     if (fir::unwrapSequenceType(fieldType).isa<fir::RecordType>())
970       return false;
971     // Allocatable components need deep copy.
972     if (auto boxType = fieldType.dyn_cast<fir::BoxType>())
973       if (boxType.getEleTy().isa<fir::HeapType>())
974         return false;
975   }
976   // Constant size components without user defined assignment and pointers can
977   // be memcopied.
978   return true;
979 }
980 
981 void fir::factory::genRecordAssignment(fir::FirOpBuilder &builder,
982                                        mlir::Location loc,
983                                        const fir::ExtendedValue &lhs,
984                                        const fir::ExtendedValue &rhs) {
985   assert(lhs.rank() == 0 && rhs.rank() == 0 && "assume scalar assignment");
986   auto baseTy = fir::dyn_cast_ptrOrBoxEleTy(fir::getBase(lhs).getType());
987   assert(baseTy && "must be a memory type");
988   // Box operands may be polymorphic, it is not entirely clear from 10.2.1.3
989   // if the assignment is performed on the dynamic of declared type. Use the
990   // runtime assuming it is performed on the dynamic type.
991   bool hasBoxOperands = fir::getBase(lhs).getType().isa<fir::BoxType>() ||
992                         fir::getBase(rhs).getType().isa<fir::BoxType>();
993   auto recTy = baseTy.dyn_cast<fir::RecordType>();
994   assert(recTy && "must be a record type");
995   if (hasBoxOperands || !recordTypeCanBeMemCopied(recTy)) {
996     auto to = fir::getBase(builder.createBox(loc, lhs));
997     auto from = fir::getBase(builder.createBox(loc, rhs));
998     // The runtime entry point may modify the LHS descriptor if it is
999     // an allocatable. Allocatable assignment is handle elsewhere in lowering,
1000     // so just create a fir.ref<fir.box<>> from the fir.box to comply with the
1001     // runtime interface, but assume the fir.box is unchanged.
1002     // TODO: does this holds true with polymorphic entities ?
1003     auto toMutableBox = builder.createTemporary(loc, to.getType());
1004     builder.create<fir::StoreOp>(loc, to, toMutableBox);
1005     fir::runtime::genAssign(builder, loc, toMutableBox, from);
1006     return;
1007   }
1008   // Otherwise, the derived type has compile time constant size and for which
1009   // the component by component assignment can be replaced by a memory copy.
1010   // Since we do not know the size of the derived type in lowering, do a
1011   // component by component assignment. Note that a single fir.load/fir.store
1012   // could be used on "small" record types, but as the type size grows, this
1013   // leads to issues in LLVM (long compile times, long IR files, and even
1014   // asserts at some point). Since there is no good size boundary, just always
1015   // use component by component assignment here.
1016   genComponentByComponentAssignment(builder, loc, lhs, rhs);
1017 }
1018 
1019 mlir::Value fir::factory::genLenOfCharacter(
1020     fir::FirOpBuilder &builder, mlir::Location loc, fir::ArrayLoadOp arrLoad,
1021     llvm::ArrayRef<mlir::Value> path, llvm::ArrayRef<mlir::Value> substring) {
1022   llvm::SmallVector<mlir::Value> typeParams(arrLoad.getTypeparams());
1023   return genLenOfCharacter(builder, loc,
1024                            arrLoad.getType().cast<fir::SequenceType>(),
1025                            arrLoad.getMemref(), typeParams, path, substring);
1026 }
1027 
1028 mlir::Value fir::factory::genLenOfCharacter(
1029     fir::FirOpBuilder &builder, mlir::Location loc, fir::SequenceType seqTy,
1030     mlir::Value memref, llvm::ArrayRef<mlir::Value> typeParams,
1031     llvm::ArrayRef<mlir::Value> path, llvm::ArrayRef<mlir::Value> substring) {
1032   auto idxTy = builder.getIndexType();
1033   auto zero = builder.createIntegerConstant(loc, idxTy, 0);
1034   auto saturatedDiff = [&](mlir::Value lower, mlir::Value upper) {
1035     auto diff = builder.create<mlir::arith::SubIOp>(loc, upper, lower);
1036     auto one = builder.createIntegerConstant(loc, idxTy, 1);
1037     auto size = builder.create<mlir::arith::AddIOp>(loc, diff, one);
1038     auto cmp = builder.create<mlir::arith::CmpIOp>(
1039         loc, mlir::arith::CmpIPredicate::sgt, size, zero);
1040     return builder.create<mlir::arith::SelectOp>(loc, cmp, size, zero);
1041   };
1042   if (substring.size() == 2) {
1043     auto upper = builder.createConvert(loc, idxTy, substring.back());
1044     auto lower = builder.createConvert(loc, idxTy, substring.front());
1045     return saturatedDiff(lower, upper);
1046   }
1047   auto lower = zero;
1048   if (substring.size() == 1)
1049     lower = builder.createConvert(loc, idxTy, substring.front());
1050   auto eleTy = fir::applyPathToType(seqTy, path);
1051   if (!fir::hasDynamicSize(eleTy)) {
1052     if (auto charTy = eleTy.dyn_cast<fir::CharacterType>()) {
1053       // Use LEN from the type.
1054       return builder.createIntegerConstant(loc, idxTy, charTy.getLen());
1055     }
1056     // Do we need to support !fir.array<!fir.char<k,n>>?
1057     fir::emitFatalError(loc,
1058                         "application of path did not result in a !fir.char");
1059   }
1060   if (fir::isa_box_type(memref.getType())) {
1061     if (memref.getType().isa<fir::BoxCharType>())
1062       return builder.create<fir::BoxCharLenOp>(loc, idxTy, memref);
1063     if (memref.getType().isa<fir::BoxType>())
1064       return CharacterExprHelper(builder, loc).readLengthFromBox(memref);
1065     fir::emitFatalError(loc, "memref has wrong type");
1066   }
1067   if (typeParams.empty()) {
1068     fir::emitFatalError(loc, "array_load must have typeparams");
1069   }
1070   if (fir::isa_char(seqTy.getEleTy())) {
1071     assert(typeParams.size() == 1 && "too many typeparams");
1072     return typeParams.front();
1073   }
1074   TODO(loc, "LEN of character must be computed at runtime");
1075 }
1076