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diff --git a/src/analysis/cfg-impl.h b/src/analysis/cfg-impl.h
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+/*
+ * Copyright 2023 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_analysis_cfg_impl_h
+#define wasm_analysis_cfg_impl_h
+
+#include "cfg.h"
+
+namespace wasm::analysis {
+
+// An iterator over a sequence of contiguous pointers (represented as a pointer
+// to a pointer in the sequence) that dereferences the pointed-to pointer.
+// TODO: Move this to its own public header if there is ever another use for it.
+template<typename T> struct _indirect_ptr_iterator {
+  using iterator_category = std::random_access_iterator_tag;
+  using value_type = T;
+  using different_type = off_t;
+  using reference = const T&;
+  using pointer = const T*;
+
+  const T* const* ptr;
+
+  const T& operator*() const { return **ptr; }
+
+  const T& operator[](int n) const { return **(ptr + n); }
+
+  _indirect_ptr_iterator& operator+=(int n) {
+    ptr += n;
+    return *this;
+  }
+
+  _indirect_ptr_iterator& operator-=(int n) {
+    ptr -= n;
+    return *this;
+  }
+
+  _indirect_ptr_iterator& operator++() { return *this += 1; }
+
+  _indirect_ptr_iterator operator++(int) {
+    _indirect_ptr_iterator it = *this;
+    ++(*this);
+    return it;
+  }
+
+  _indirect_ptr_iterator& operator--() { return *this -= 1; }
+
+  _indirect_ptr_iterator operator--(int) {
+    _indirect_ptr_iterator it = *this;
+    --(*this);
+    return it;
+  }
+
+  _indirect_ptr_iterator operator+(int n) const {
+    _indirect_ptr_iterator it = *this;
+    it += n;
+    return it;
+  }
+
+  _indirect_ptr_iterator operator-(int n) const {
+    _indirect_ptr_iterator it = *this;
+    it -= n;
+    return it;
+  }
+
+  bool operator==(const _indirect_ptr_iterator& other) const {
+    return ptr == other.ptr;
+  }
+
+  bool operator!=(const _indirect_ptr_iterator& other) const {
+    return !(*this == other);
+  }
+
+  bool operator<(const _indirect_ptr_iterator& other) const {
+    return ptr < other.ptr;
+  }
+
+  bool operator>(const _indirect_ptr_iterator& other) const {
+    return ptr > other.ptr;
+  }
+
+  bool operator<=(const _indirect_ptr_iterator& other) const {
+    return ptr <= other.ptr;
+  }
+
+  bool operator>=(const _indirect_ptr_iterator& other) const {
+    return ptr >= other.ptr;
+  }
+};
+
+template<typename T>
+_indirect_ptr_iterator<T> operator+(int n,
+                                    const _indirect_ptr_iterator<T>& it) {
+  return it + n;
+}
+
+// Wraps a vector of pointers and provides dereferencing iterators for it.
+template<typename T> struct _indirect_ptr_vec {
+  using iterator = _indirect_ptr_iterator<T>;
+
+  const std::vector<T*>& vec;
+
+  _indirect_ptr_vec(const std::vector<T*>& vec) : vec(vec) {}
+
+  iterator begin() const { return {&vec.data()[0]}; }
+  iterator end() const { return {&vec.data()[vec.size()]}; }
+};
+
+struct BasicBlock::Predecessors : _indirect_ptr_vec<BasicBlock> {
+  Predecessors(const BasicBlock& block)
+    : _indirect_ptr_vec(block.predecessors) {}
+};
+
+struct BasicBlock::Successors : _indirect_ptr_vec<BasicBlock> {
+  Successors(const BasicBlock& block) : _indirect_ptr_vec(block.successors) {}
+};
+
+inline BasicBlock::Predecessors BasicBlock::preds() const {
+  return Predecessors(*this);
+}
+
+inline BasicBlock::Successors BasicBlock::succs() const {
+  return Successors(*this);
+}
+
+} // namespace wasm::analysis
+
+#endif // wasm_analysis_cfg_impl_h