[llvm] 9e932e0 - [ADT] Fix DenseMapInfo<variant>::isEqual to delegate to DenseMapInfo, not ==
Sam McCall via llvm-commits
llvm-commits at lists.llvm.org
Tue Jun 6 09:36:59 PDT 2023
Author: Sam McCall
Date: 2023-06-06T18:36:37+02:00
New Revision: 9e932e08a8300f3366ace04ba8fda4946db406b9
URL: https://github.com/llvm/llvm-project/commit/9e932e08a8300f3366ace04ba8fda4946db406b9
DIFF: https://github.com/llvm/llvm-project/commit/9e932e08a8300f3366ace04ba8fda4946db406b9.diff
LOG: [ADT] Fix DenseMapInfo<variant>::isEqual to delegate to DenseMapInfo, not ==
Differential Revision: https://reviews.llvm.org/D151557
Added:
Modified:
llvm/include/llvm/ADT/DenseMapInfo.h
llvm/unittests/ADT/DenseMapTest.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/ADT/DenseMapInfo.h b/llvm/include/llvm/ADT/DenseMapInfo.h
index 1c00fb699cc22..2c227be0082ab 100644
--- a/llvm/include/llvm/ADT/DenseMapInfo.h
+++ b/llvm/include/llvm/ADT/DenseMapInfo.h
@@ -318,7 +318,22 @@ template <typename... Ts> struct DenseMapInfo<std::variant<Ts...>> {
}
static bool isEqual(const Variant &LHS, const Variant &RHS) {
- return LHS == RHS;
+ if (LHS.index() != RHS.index())
+ return false;
+ if (LHS.valueless_by_exception())
+ return true;
+ // We want to dispatch to DenseMapInfo<T>::isEqual(LHS.get(I), RHS.get(I))
+ // We know the types are the same, but std::visit(V, LHS, RHS) doesn't.
+ // We erase the type held in LHS to void*, and dispatch over RHS.
+ const void *ErasedLHS =
+ std::visit([](const auto &LHS) -> const void * { return &LHS; }, LHS);
+ return std::visit(
+ [&](const auto &RHS) -> bool {
+ using T = std::remove_cv_t<std::remove_reference_t<decltype(RHS)>>;
+ return DenseMapInfo<T>::isEqual(*static_cast<const T *>(ErasedLHS),
+ RHS);
+ },
+ RHS);
}
};
} // end namespace llvm
diff --git a/llvm/unittests/ADT/DenseMapTest.cpp b/llvm/unittests/ADT/DenseMapTest.cpp
index 79d57d35265c2..ba5cd4c4fca4d 100644
--- a/llvm/unittests/ADT/DenseMapTest.cpp
+++ b/llvm/unittests/ADT/DenseMapTest.cpp
@@ -690,6 +690,10 @@ struct A {
struct B : public A {
using A::A;
};
+
+struct AlwaysEqType {
+ bool operator==(const AlwaysEqType &RHS) const { return true; }
+};
} // namespace
namespace llvm {
@@ -702,6 +706,16 @@ struct DenseMapInfo<T, std::enable_if_t<std::is_base_of_v<A, T>>> {
return LHS.value == RHS.value;
}
};
+
+template <> struct DenseMapInfo<AlwaysEqType> {
+ using T = AlwaysEqType;
+ static inline T getEmptyKey() { return {}; }
+ static inline T getTombstoneKey() { return {}; }
+ static unsigned getHashValue(const T &Val) { return 0; }
+ static bool isEqual(const T &LHS, const T &RHS) {
+ return false;
+ }
+};
} // namespace llvm
namespace {
@@ -725,16 +739,20 @@ TEST(DenseMapCustomTest, SFINAEMapInfo) {
}
TEST(DenseMapCustomTest, VariantSupport) {
- using variant = std::variant<int, int>;
+ using variant = std::variant<int, int, AlwaysEqType>;
DenseMap<variant, int> Map;
variant Keys[] = {
variant(std::in_place_index<0>, 1),
variant(std::in_place_index<1>, 1),
+ variant(std::in_place_index<2>),
};
Map.try_emplace(Keys[0], 0);
Map.try_emplace(Keys[1], 1);
EXPECT_THAT(Map, testing::SizeIs(2));
EXPECT_NE(DenseMapInfo<variant>::getHashValue(Keys[0]),
DenseMapInfo<variant>::getHashValue(Keys[1]));
+ // Check that isEqual dispatches to isEqual of underlying type, and not to
+ // operator==.
+ EXPECT_FALSE(DenseMapInfo<variant>::isEqual(Keys[2], Keys[2]));
}
} // namespace
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