[clang-reorder-fields] Support designated initializers

clang-tools-extra/clang-reorder-fields/CMakeLists.txt

@@ -4,6 +4,7 @@ set(LLVM_LINK_COMPONENTS
 )
 
 add_clang_library(clangReorderFields STATIC
+  Designator.cpp
   ReorderFieldsAction.cpp
 
   DEPENDS

clang-tools-extra/clang-reorder-fields/Designator.cpp

@@ -0,0 +1,219 @@
+//===-- tools/extra/clang-reorder-fields/utils/Designator.cpp ---*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains the definition of the Designator and Designators utility
+/// classes.
+///
+//===----------------------------------------------------------------------===//
+
+#include "Designator.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Expr.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace clang {
+namespace reorder_fields {
+
+void Designator::advanceToNextField() {
+  assert(!isFinished() && "Iterator is already finished");
+  switch (Tag) {
+  case STRUCT:
+    if (StructIt.Record->isUnion()) {
+      // Union always finishes on first increment.
+      StructIt.Field = StructIt.Record->field_end();
+      Type = QualType();
+      break;
+    }
+    ++StructIt.Field;
+    if (StructIt.Field != StructIt.Record->field_end()) {
+      Type = StructIt.Field->getType();
+    } else {
+      Type = QualType();
+    }
+    break;
+  case ARRAY:
+    ++ArrayIt.Index;
+    break;
+  case ARRAY_RANGE:
+    ArrayIt.Index = ArrayRangeIt.End + 1;
+    ArrayIt.Size = ArrayRangeIt.Size;
+    Tag = ARRAY;
+    break;
+  }
+}
+
+bool Designator::isFinished() {
+  switch (Tag) {
+  case STRUCT:
+    return StructIt.Field == StructIt.Record->field_end();
+  case ARRAY:
+    return ArrayIt.Index == ArrayIt.Size;
+  case ARRAY_RANGE:
+    return ArrayRangeIt.End == ArrayRangeIt.Size;
+  }
+  return false;
+}
+
+Designators::Designators(const Expr *Init, const InitListExpr *ILE,
+                         const ASTContext *Context)
+    : ILE(ILE), Context(Context) {
+  if (ILE->getType()->isArrayType()) {
+    const ConstantArrayType *CAT =
+        Context->getAsConstantArrayType(ILE->getType());
+    // Only constant size arrays are supported.
+    if (!CAT) {
+      DesignatorList.clear();
+      return;
+    }
+    DesignatorList.push_back(
+        {CAT->getElementType(), 0, CAT->getSize().getZExtValue()});
+  } else {
+    const RecordDecl *DesignatorRD = ILE->getType()->getAsRecordDecl();
+    DesignatorList.push_back({DesignatorRD->field_begin()->getType(),
+                              DesignatorRD->field_begin(), DesignatorRD});
+  }
+
+  // If the designator list is empty at this point, then there must be excess
+  // elements in the initializer list. They are not currently supported.
+  if (DesignatorList.empty())
+    return;
+
+  if (!enterImplicitInitLists(Init))
+    DesignatorList.clear();
+}
+
+Designators::Designators(const DesignatedInitExpr *DIE, const InitListExpr *ILE,
+                         const ASTContext *Context)
+    : ILE(ILE), Context(Context) {
+  for (const auto &D : DIE->designators()) {
+    if (D.isFieldDesignator()) {
+      RecordDecl *DesignatorRecord = D.getFieldDecl()->getParent();
+      for (auto FieldIt = DesignatorRecord->field_begin();
+           FieldIt != DesignatorRecord->field_end(); ++FieldIt) {
+        if (*FieldIt == D.getFieldDecl()) {
+          DesignatorList.push_back(
+              {FieldIt->getType(), FieldIt, DesignatorRecord});
+          break;
+        }
+      }
+    } else {
+      const QualType CurrentType = DesignatorList.empty()
+                                       ? ILE->getType()
+                                       : DesignatorList.back().getType();
+      const ConstantArrayType *CAT =
+          Context->getAsConstantArrayType(CurrentType);
+      if (!CAT) {
+        // Non-constant-sized arrays are not supported.
+        DesignatorList.clear();
+        return;
+      }
+      if (D.isArrayDesignator()) {
+        DesignatorList.push_back({CAT->getElementType(),
+                                  DIE->getArrayIndex(D)
+                                      ->EvaluateKnownConstInt(*Context)
+                                      .getZExtValue(),
+                                  CAT->getSize().getZExtValue()});
+      } else if (D.isArrayRangeDesignator()) {
+        DesignatorList.push_back({CAT->getElementType(),
+                                  DIE->getArrayRangeStart(D)
+                                      ->EvaluateKnownConstInt(*Context)
+                                      .getZExtValue(),
+                                  DIE->getArrayRangeEnd(D)
+                                      ->EvaluateKnownConstInt(*Context)
+                                      .getZExtValue(),
+                                  CAT->getSize().getZExtValue()});
+      } else {
+        llvm_unreachable("Unexpected designator kind");
+      }
+    }
+  }
+}
+
+bool Designators::advanceToNextField(const Expr *Init) {
+  // Remove all designators that refer to the last field of a struct or final
+  // element of the array.
+  while (!DesignatorList.empty()) {
+    auto &CurrentDesignator = DesignatorList.back();
+    CurrentDesignator.advanceToNextField();
+    if (CurrentDesignator.isFinished()) {
+      DesignatorList.pop_back();
+      continue;
+    }
+    break;
+  }
+
+  // If the designator list is empty at this point, then there must be excess
+  // elements in the initializer list. They are not currently supported.
+  if (DesignatorList.empty())
+    return false;
+
+  if (!enterImplicitInitLists(Init)) {
+    DesignatorList.clear();
+    return false;
+  }
+
+  return true;
+}
+
+bool Designators::enterImplicitInitLists(const Expr *Init) {
+  // Check for missing braces by comparing the type of the last designator and
+  // type of Init.
+  while (true) {
+    const QualType T = DesignatorList.back().getType();
+    // If the types match, there are no missing braces.
+    if (Init->getType() == T)
+      break;
+
+    // If the current type is a struct, then get its first field.
+    if (T->isRecordType()) {
+      DesignatorList.push_back({T->getAsRecordDecl()->field_begin()->getType(),
+                                T->getAsRecordDecl()->field_begin(),
+                                T->getAsRecordDecl()});
+      continue;
+    }
+    // If the current type is an array, then get its first element.
+    if (T->isArrayType()) {
+      DesignatorList.push_back(
+          {Context->getAsArrayType(T)->getElementType(), 0,
+           Context->getAsConstantArrayType(T)->getSize().getZExtValue()});
+      continue;
+    }
+
+    // The initializer doesn't match the expected type. The initializer list is
+    // invalid.
+    return false;
+  }
+
+  return true;
+}
+
+std::string Designators::toString() const {
+  if (DesignatorList.empty())
+    return "";
+  std::string Designator;
+  llvm::raw_string_ostream OS(Designator);
+  for (auto &I : DesignatorList) {
+    switch (I.getTag()) {
+    case Designator::STRUCT:
+      OS << '.' << I.getStructIter()->getName();
+      break;
+    case Designator::ARRAY:
+      OS << '[' << I.getArrayIndex() << ']';
+      break;
+    case Designator::ARRAY_RANGE:
+      OS << '[' << I.getArrayRangeStart() << "..." << I.getArrayRangeEnd()
+         << ']';
+    }
+  }
+  OS << " = ";
+  return Designator;
+}
+
+} // namespace reorder_fields
+} // namespace clang

clang-tools-extra/clang-reorder-fields/Designator.h

@@ -0,0 +1,165 @@
+//===-- tools/extra/clang-reorder-fields/utils/Designator.h -----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains the declarations of the Designator and Designators
+/// utility classes.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_REORDER_FIELDS_UTILS_DESIGNATOR_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_REORDER_FIELDS_UTILS_DESIGNATOR_H
+
+#include "clang/AST/Decl.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/Type.h"
+
+namespace clang {
+namespace reorder_fields {
+
+/// Represents a part of a designation in a C99/C++20 designated initializer. It
+/// is a tagged union of different kinds of designators: struct, array and array
+/// range. Holds enough information to be able to advance to the next field and
+/// to know when all fields have been iterated through.
+class Designator {
+public:
+  enum Kind { STRUCT, ARRAY, ARRAY_RANGE };
+
+  Designator(const QualType Type, RecordDecl::field_iterator Field,
+             const RecordDecl *RD)
+      : Tag(STRUCT), Type(Type), StructIt({Field, RD}) {}
+
+  Designator(const QualType Type, uint64_t Idx, uint64_t Size)
+      : Tag(ARRAY), Type(Type), ArrayIt({Idx, Size}) {}
+
+  Designator(const QualType Type, uint64_t Start, uint64_t End, uint64_t Size)
+      : Tag(ARRAY_RANGE), Type(Type), ArrayRangeIt({Start, End, Size}) {}
+
+  /// Moves the iterator to the next element.
+  void advanceToNextField();
+
+  /// Checks if the iterator has iterated through all elements.
+  bool isFinished();
+
+  Kind getTag() const { return Tag; }
+  QualType getType() const { return Type; }
+
+  const RecordDecl::field_iterator getStructIter() const {
+    assert(Tag == STRUCT && "Must be a field designator");
+    return StructIt.Field;
+  }
+
+  const RecordDecl *getStructDecl() const {
+    assert(Tag == STRUCT && "Must be a field designator");
+    return StructIt.Record;
+  }
+
+  uint64_t getArrayIndex() const {
+    assert(Tag == ARRAY && "Must be an array designator");
+    return ArrayIt.Index;
+  }
+
+  uint64_t getArrayRangeStart() const {
+    assert(Tag == ARRAY_RANGE && "Must be an array range designator");
+    return ArrayRangeIt.Start;
+  }
+
+  uint64_t getArrayRangeEnd() const {
+    assert(Tag == ARRAY_RANGE && "Must be an array range designator");
+    return ArrayRangeIt.End;
+  }
+
+  uint64_t getArraySize() const {
+    assert((Tag == ARRAY || Tag == ARRAY_RANGE) &&
+           "Must be an array or range designator");
+    if (Tag == ARRAY)
+      return ArrayIt.Size;
+    return ArrayRangeIt.Size;
+  }
+
+private:
+  /// Type of the designator.
+  Kind Tag;
+
+  /// Type of the designated entry. For arrays this is the type of the element.
+  QualType Type;
+
+  /// Field designator has the iterator to the field and the record the field
+  /// is declared in.
+  struct StructIter {
+    RecordDecl::field_iterator Field;
+    const RecordDecl *Record;
+  };
+
+  /// Array designator has an index and size of the array.
+  struct ArrayIter {
+    uint64_t Index;
+    uint64_t Size;
+  };
+
+  /// Array range designator has a start and end index and size of the array.
+  struct ArrayRangeIter {
+    uint64_t Start;
+    uint64_t End;
+    uint64_t Size;
+  };
+
+  union {
+    StructIter StructIt;
+    ArrayIter ArrayIt;
+    ArrayRangeIter ArrayRangeIt;
+  };
+};
+
+/// List of designators.
+class Designators {
+public:
+  /// Initialize to the first member of the struct/array. Enters implicit
+  /// initializer lists until a type that matches Init is found.
+  Designators(const Expr *Init, const InitListExpr *ILE,
+              const ASTContext *Context);
+
+  /// Initialize to the designators of the given expression.
+  Designators(const DesignatedInitExpr *DIE, const InitListExpr *ILE,
+              const ASTContext *Context);
+
+  /// Return whether this designator list is valid.
+  bool isValid() const { return !DesignatorList.empty(); }
+
+  /// Moves the designators to the next initializer in the struct/array. If the
+  /// type of next initializer doesn't match the expected type then there are
+  /// omitted braces and we add new designators to reflect that.
+  bool advanceToNextField(const Expr *Init);
+
+  /// Gets a string representation from a list of designators. This string will
+  /// be inserted before an initializer expression to make it designated.
+  std::string toString() const;
+
+  size_t size() const { return DesignatorList.size(); }
+
+  SmallVector<Designator>::const_iterator begin() const {
+    return DesignatorList.begin();
+  }
+  SmallVector<Designator>::const_iterator end() const {
+    return DesignatorList.end();
+  }
+
+private:
+  /// Enters any implicit initializer lists until a type that matches the given
+  /// expression is found.
+  bool enterImplicitInitLists(const Expr *Init);
+
+  const InitListExpr *ILE;
+  const ASTContext *Context;
+  SmallVector<Designator, 1> DesignatorList;
+};
+
+} // namespace reorder_fields
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_REORDER_FIELDS_UTILS_DESIGNATOR_H