DenseMapInfo: support std::optional<T>

[elijahkin]

No description provided.

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[llvmbot]

@llvm/pr-subscribers-llvm-adt

Author: Elijah Kin (elijahkin)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/147851.diff

2 Files Affected:

• (modified) llvm/include/llvm/ADT/DenseMapInfo.h (+29)
• (modified) llvm/unittests/ADT/DenseMapTest.cpp (+4-1)

diff --git a/llvm/include/llvm/ADT/DenseMapInfo.h b/llvm/include/llvm/ADT/DenseMapInfo.h
index 07c37e353a40b..65c607910d089 100644
--- a/llvm/include/llvm/ADT/DenseMapInfo.h
+++ b/llvm/include/llvm/ADT/DenseMapInfo.h
@@ -320,6 +320,35 @@ struct DenseMapInfo<Enum, std::enable_if_t<std::is_enum_v<Enum>>> {
 
   static bool isEqual(const Enum &LHS, const Enum &RHS) { return LHS == RHS; }
 };
+
+template <typename T>
+struct DenseMapInfo<std::optional<T>> {
+  using Optional = std::optional<T>;
+  using Info = DenseMapInfo<T>;
+
+  static inline Optional getEmptyKey() {
+    return std::make_optional(Info::getEmptyKey());
+  }
+
+  static inline Optional getTombstoneKey() {
+    return std::make_optional(Info::getTombstoneKey());
+  }
+
+  static unsigned getHashValue(const Optional &OptionalVal) {
+    return detail::combineHashValue(
+        OptionalVal.has_value(),
+        Info::getHashValue(OptionalVal.value_or(Info::getEmptyKey())));
+  }
+
+  static bool isEqual(const Optional &LHS, const Optional &RHS) {
+    if (LHS.has_value() && RHS.has_value()) {
+      return Info::isEqual(LHS.value(), RHS.value());
+    } else if (!LHS.has_value() && !RHS.has_value()) {
+      return true;
+    }
+    return false;
+  }
+};
 } // end namespace llvm
 
 #endif // LLVM_ADT_DENSEMAPINFO_H
diff --git a/llvm/unittests/ADT/DenseMapTest.cpp b/llvm/unittests/ADT/DenseMapTest.cpp
index c95f96c4bb3c6..ca04dc055fd11 100644
--- a/llvm/unittests/ADT/DenseMapTest.cpp
+++ b/llvm/unittests/ADT/DenseMapTest.cpp
@@ -15,6 +15,7 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include <map>
+#include <optional>
 #include <set>
 #include <utility>
 #include <variant>
@@ -117,11 +118,13 @@ typedef ::testing::Types<DenseMap<uint32_t, uint32_t>,
                          DenseMap<uint32_t *, uint32_t *>,
                          DenseMap<CtorTester, CtorTester, CtorTesterMapInfo>,
                          DenseMap<EnumClass, uint32_t>,
+                         DenseMap<std::optional<uint32_t>, uint32_t>,
                          SmallDenseMap<uint32_t, uint32_t>,
                          SmallDenseMap<uint32_t *, uint32_t *>,
                          SmallDenseMap<CtorTester, CtorTester, 4,
                                        CtorTesterMapInfo>,
-                         SmallDenseMap<EnumClass, uint32_t>
+                         SmallDenseMap<EnumClass, uint32_t>,
+                         SmallDenseMap<std::optional<uint32_t>, uint32_t>
                          > DenseMapTestTypes;
 // clang-format on
 

[elijahkin]

@nikic @kuhar @phisiart

[dwblaikie]

One minor thing, otherwise looks good.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[kuhar]

Do we need to use make_optional here? I'd think a simple return {foo}; or return Optional{foo}; should work. Also below.