[Support] Extend ExtensibleRTTI utility to support basic multiple inheritance. #112643
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@llvm/pr-subscribers-llvm-support Author: Lang Hames (lhames) ChangesClients can now pass multiple parent classes to RTTIExtends. Each parent class will be inherited from publicly (and non-virtually). The isa, cast, and dyn_cast methods will now work as expected for types with multiple inheritance. Full diff: https://github.com/llvm/llvm-project/pull/112643.diff 2 Files Affected:
diff --git a/llvm/include/llvm/Support/ExtensibleRTTI.h b/llvm/include/llvm/Support/ExtensibleRTTI.h
index d3193be6f529e1..6b8f5efd6bd81a 100644
--- a/llvm/include/llvm/Support/ExtensibleRTTI.h
+++ b/llvm/include/llvm/Support/ExtensibleRTTI.h
@@ -81,10 +81,6 @@ class RTTIRoot {
return ClassID == classID();
}
- /// Check whether this instance is a subclass of QueryT.
- template <typename QueryT>
- bool isA() const { return isA(QueryT::classID()); }
-
private:
virtual void anchor();
@@ -110,21 +106,37 @@ class RTTIRoot {
/// static char ID;
/// };
///
-template <typename ThisT, typename ParentT>
-class RTTIExtends : public ParentT {
+template <typename ThisT, typename... ParentTs>
+class RTTIExtends : public ParentTs... {
public:
// Inherit constructors from ParentT.
- using ParentT::ParentT;
+ using ParentTs::ParentTs...;
static const void *classID() { return &ThisT::ID; }
const void *dynamicClassID() const override { return &ThisT::ID; }
+ /// Check whether this instance is a subclass of QueryT.
+ template <typename QueryT>
+ bool isA() const { return isA(QueryT::classID()); }
+
bool isA(const void *const ClassID) const override {
- return ClassID == classID() || ParentT::isA(ClassID);
+ return ClassID == classID() || parentsAreA<ParentTs...>(ClassID);
+ }
+
+ template <typename T>
+ static bool classof(const T *R) { return R->template isA<ThisT>(); }
+private:
+
+ template <typename T>
+ bool parentsAreA(const void *const ClassID) const {
+ return T::isA(ClassID);
}
- static bool classof(const RTTIRoot *R) { return R->isA<ThisT>(); }
+ template <typename T, typename T2, typename... Ts>
+ bool parentsAreA(const void *const ClassID) const {
+ return T::isA(ClassID) || parentsAreA<T2, Ts...>(ClassID);
+ }
};
} // end namespace llvm
diff --git a/llvm/unittests/Support/ExtensibleRTTITest.cpp b/llvm/unittests/Support/ExtensibleRTTITest.cpp
index 9715d26a9de297..4d781066903e88 100644
--- a/llvm/unittests/Support/ExtensibleRTTITest.cpp
+++ b/llvm/unittests/Support/ExtensibleRTTITest.cpp
@@ -36,15 +36,24 @@ class MyDeeperDerivedType
static char ID;
};
+class MyMultipleInheritanceType
+ : public RTTIExtends<MyMultipleInheritanceType,
+ MyDerivedType, MyOtherDerivedType> {
+public:
+ static char ID;
+};
+
char MyBaseType::ID = 0;
char MyDerivedType::ID = 0;
char MyOtherDerivedType::ID = 0;
char MyDeeperDerivedType::ID = 0;
+char MyMultipleInheritanceType::ID = 0;
TEST(ExtensibleRTTI, isa) {
MyBaseType B;
MyDerivedType D;
MyDeeperDerivedType DD;
+ MyMultipleInheritanceType MI;
EXPECT_TRUE(isa<MyBaseType>(B));
EXPECT_FALSE(isa<MyDerivedType>(B));
@@ -60,26 +69,53 @@ TEST(ExtensibleRTTI, isa) {
EXPECT_TRUE(isa<MyDerivedType>(DD));
EXPECT_FALSE(isa<MyOtherDerivedType>(DD));
EXPECT_TRUE(isa<MyDeeperDerivedType>(DD));
+
+ EXPECT_TRUE(isa<MyBaseType>(MI));
+ EXPECT_TRUE(isa<MyDerivedType>(MI));
+ EXPECT_TRUE(isa<MyOtherDerivedType>(MI));
+ EXPECT_FALSE(isa<MyDeeperDerivedType>(MI));
+ EXPECT_TRUE(isa<MyMultipleInheritanceType>(MI));
}
TEST(ExtensibleRTTI, cast) {
- MyDerivedType D;
- MyBaseType &BD = D;
-
- (void)cast<MyBaseType>(D);
- (void)cast<MyBaseType>(BD);
- (void)cast<MyDerivedType>(BD);
+ MyMultipleInheritanceType MI;
+ MyDerivedType &D = MI;
+ MyOtherDerivedType &OD = MI;
+ MyBaseType &B = D;
+
+ EXPECT_EQ(&cast<MyBaseType>(D), &B);
+ EXPECT_EQ(&cast<MyDerivedType>(MI), &D);
+ EXPECT_EQ(&cast<MyOtherDerivedType>(MI), &OD);
+ EXPECT_EQ(&cast<MyMultipleInheritanceType>(MI), &MI);
}
TEST(ExtensibleRTTI, dyn_cast) {
- MyBaseType B;
- MyDerivedType D;
+ MyMultipleInheritanceType MI;
+ MyDerivedType &D = MI;
+ MyOtherDerivedType &OD = MI;
MyBaseType &BD = D;
+ MyBaseType &BOD = OD;
- EXPECT_EQ(dyn_cast<MyDerivedType>(&B), nullptr);
- EXPECT_EQ(dyn_cast<MyDerivedType>(&D), &D);
EXPECT_EQ(dyn_cast<MyBaseType>(&BD), &BD);
EXPECT_EQ(dyn_cast<MyDerivedType>(&BD), &D);
+
+ EXPECT_EQ(dyn_cast<MyBaseType>(&BOD), &BOD);
+ EXPECT_EQ(dyn_cast<MyOtherDerivedType>(&BOD), &OD);
+
+ EXPECT_EQ(dyn_cast<MyBaseType>(&D), &BD);
+ EXPECT_EQ(dyn_cast<MyDerivedType>(&D), &D);
+ EXPECT_EQ(dyn_cast<MyMultipleInheritanceType>(&D), &MI);
+
+ EXPECT_EQ(dyn_cast<MyBaseType>(&OD), &BOD);
+ EXPECT_EQ(dyn_cast<MyOtherDerivedType>(&OD), &OD);
+ EXPECT_EQ(dyn_cast<MyMultipleInheritanceType>(&OD), &MI);
+
+ EXPECT_EQ(dyn_cast<MyDerivedType>(&MI), &D);
+ EXPECT_EQ(dyn_cast<MyMultipleInheritanceType>(&MI), &MI);
+
+ EXPECT_EQ(dyn_cast<MyDerivedType>(&MI), &D);
+ EXPECT_EQ(dyn_cast<MyOtherDerivedType>(&MI), &OD);
+ EXPECT_EQ(dyn_cast<MyMultipleInheritanceType>(&MI), &MI);
}
} // namespace
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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The motivating use-case is ORC memory management: We want |
…eritance. Clients can now pass multiple parent classes to RTTIExtends. Each parent class will be inherited from publicly (and non-virtually). The isa, cast, and dyn_cast methods will now work as expected for types with multiple inheritance.
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dwblaikie
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Oct 17, 2024
| public: | ||
| // Inherit constructors from ParentT. | ||
| using ParentT::ParentT; | ||
| using ParentTs::ParentTs...; |
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Does this still apply - I guess it only works if you want to call one of the base ctors and all the other bases support default construction?
Probably OK as a first step - but maybe needs a FIXME to add something like std::pair's piecewise construct (though interesting that tuple doesn't have that... )
dwblaikie
reviewed
Oct 17, 2024
| bool isA(const void *const ClassID) const override { | ||
| return ClassID == classID() || ParentT::isA(ClassID); | ||
| return ClassID == classID() || parentsAreA<ParentTs...>(ClassID); |
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Might be able to skip the parentsAreA helper:
return ClassId == classId() || (ParentTs::isA(ClassID) || ...);
(here's at least a little proof of concept I did: https://godbolt.org/z/vGca7jYbT )
benlangmuir
approved these changes
Oct 21, 2024
dwblaikie
approved these changes
Oct 24, 2024
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/88/builds/3856 Here is the relevant piece of the build log for the reference |
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NoumanAmir657
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Nov 4, 2024
…eritance. (llvm#112643) Clients can now pass multiple parent classes to RTTIExtends. Each parent class will be inherited from publicly (and non-virtually). The isa, cast, and dyn_cast methods will now work as expected for types with multiple inheritance.
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Clients can now pass multiple parent classes to RTTIExtends. Each parent class will be inherited from publicly (and non-virtually). The isa, cast, and dyn_cast methods will now work as expected for types with multiple inheritance.