[clang] [clang][ssaf] Add UnsafeBufferUsage summary data structures (PR #181067)

[Ziqing Luo via cfe-commits]

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+//===- UnsafeBufferUsage.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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_ANALYSIS_SCALABLE_ANALYSES_UNSAFEBUFFERUSAGE_H
+#define LLVM_CLANG_ANALYSIS_SCALABLE_ANALYSES_UNSAFEBUFFERUSAGE_H
+
+#include "clang/Analysis/Scalable/Model/EntityId.h"
+#include "clang/Analysis/Scalable/Model/SummaryName.h"
+#include "clang/Analysis/Scalable/TUSummary/EntitySummary.h"
+#include "llvm/ADT/iterator_range.h"
+#include <set>
+
+namespace clang::ssaf {
+
+/// An EntityPointerLevel represents a level of the declared pointer
+/// type of an entity.  In the fully-expanded spelling of the declared type, a
+/// EntityPointerLevel is associated with a '*' in that declaration.
+///
+/// For example, for 'int **p;', there are two EntityPointerLevels. One
+/// is associated with 'int **' of 'p' and the other is associated with 'int *'
+/// of 'p'.
+///
+/// An EntityPointerLevel can be identified by an EntityId and an unsigned
+/// integer indicating the pointer level: '(EntityId, PointerLevel)'.  A
+/// EntityPointerLevel 'P' is valid iff
+///   - 'P.EntityId' has a pointer type with at least 'P.PointerLevel' levels
+///     (This implies 'P.PointerLevel > 0');
+///   - 'P.EntityId' identifies an lvalue object and 'P.PointerLevel == 0'.
+/// The latter case represents address-of expressions.
+///
+/// For the same example 'int **p;', the EntityPointerLevels below are valid:
+/// '(p, 1)' is associated with 'int **' of 'p';
+/// '(p, 2)' is associated with 'int *' of 'p';
+/// '(p, 0)' represents '&p'.
+class EntityPointerLevel {
+  EntityId Entity;
+  unsigned PointerLevel;
+
+  friend class UnsafeBufferUsageTUSummaryBuilder;
+  friend class UnsafeBufferUsageEntitySummary;
+
+  EntityPointerLevel(EntityId Entity, unsigned PointerLevel)
+      : Entity(Entity), PointerLevel(PointerLevel) {}
+
+public:
+  EntityId getEntity() const { return Entity; }
+  unsigned getPointerLevel() const { return PointerLevel; }
+
+  bool operator==(const EntityPointerLevel &Other) const {
+    return Entity == Other.Entity && PointerLevel == Other.PointerLevel;
+  }
+
+  bool operator!=(const EntityPointerLevel &Other) const {
+    return !(*this == Other);
+  }
+
+  bool operator<(const EntityPointerLevel &Other) const {
+    return std::tie(Entity, PointerLevel) <
+           std::tie(Other.Entity, Other.PointerLevel);
+  }
+
+  // Comparator supporting partial comparison against EntityId:
+  struct Comparator {
+    using is_transparent = void;
+    bool operator()(const EntityPointerLevel &L,
+                    const EntityPointerLevel &R) const {
+      return L < R;
+    }
+    bool operator()(const EntityId &L, const EntityPointerLevel &R) const {
+      return L < R.getEntity();
+    }
+    bool operator()(const EntityPointerLevel &L, const EntityId &R) const {
+      return L.getEntity() < R;
+    }
+  };
+};
+
+using EntityPointerLevelSet =
+    std::set<EntityPointerLevel, EntityPointerLevel::Comparator>;
+
+/// An UnsafeBufferUsageEntitySummary is an immutable set of unsafe buffers, in
+/// the form of EntityPointerLevel.
+class UnsafeBufferUsageEntitySummary final : public EntitySummary {
+  const EntityPointerLevelSet UnsafeBuffers;
+
+  friend class UnsafeBufferUsageTUSummaryBuilder;
+
+  UnsafeBufferUsageEntitySummary(EntityPointerLevelSet &&UnsafeBuffers)
+      : EntitySummary(), UnsafeBuffers(std::move(UnsafeBuffers)) {}
+
+public:
+  using const_iterator = EntityPointerLevelSet::const_iterator;
+
+  const_iterator begin() const { return UnsafeBuffers.begin(); }
+  const_iterator end() const { return UnsafeBuffers.end(); }
+
+  const_iterator find(const EntityPointerLevel &V) const {
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ziqingluo-90 wrote:

Aren't `EntitySummary`s eventually read by some component?

https://github.com/llvm/llvm-project/pull/181067