oydale created this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
A placeholder instruction for use in generation of cleanup code for an
initializer list would not be emitted if the base class contained a
non-trivial destructor and the class contains no fields of its own. This
would be the case when using CTAD to deduce the template arguments for a
struct with an overloaded call operator, e.g.
template <class... Ts> struct ctad : Ts... {};
template <class... Ts> ctad(Ts...)->ctad<Ts...>;
and this class was initialized with a list of lambdas capturing by copy,
e.g.
ctad c {[s](short){}, [s](long){}};
In a release build the bug would manifest itself as a crash in the SROA
pass, however, in a debug build the following assert in CGCleanup.cpp
would fail:
assert(dominatingIP && "no existing variable and no dominating IP!");
By ensuring that a placeholder instruction is emitted even if there's no
fields in the class, neither the assert nor the crash is reproducible.
See https://bugs.llvm.org/show_bug.cgi?id=40771
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D64656
Files:
clang/lib/CodeGen/CGExprAgg.cpp
Index: clang/lib/CodeGen/CGExprAgg.cpp
===================================================================
--- clang/lib/CodeGen/CGExprAgg.cpp
+++ clang/lib/CodeGen/CGExprAgg.cpp
@@ -1618,6 +1618,14 @@
GEP->eraseFromParent();
}
+ // Base class has a destructor and there's no fields in the class itself,
+ // create a placeholder here since we did not create one earlier.
+ if (!cleanupDominator && !cleanups.empty())
+ cleanupDominator = CGF.Builder.CreateAlignedLoad(
+ CGF.Int8Ty,
+ llvm::Constant::getNullValue(CGF.Int8PtrTy),
+ CharUnits::One()); // placeholder
+
// Deactivate all the partial cleanups in reverse order, which
// generally means popping them.
for (unsigned i = cleanups.size(); i != 0; --i)
Index: clang/lib/CodeGen/CGExprAgg.cpp
===================================================================
--- clang/lib/CodeGen/CGExprAgg.cpp
+++ clang/lib/CodeGen/CGExprAgg.cpp
@@ -1618,6 +1618,14 @@
GEP->eraseFromParent();
}
+ // Base class has a destructor and there's no fields in the class itself,
+ // create a placeholder here since we did not create one earlier.
+ if (!cleanupDominator && !cleanups.empty())
+ cleanupDominator = CGF.Builder.CreateAlignedLoad(
+ CGF.Int8Ty,
+ llvm::Constant::getNullValue(CGF.Int8PtrTy),
+ CharUnits::One()); // placeholder
+
// Deactivate all the partial cleanups in reverse order, which
// generally means popping them.
for (unsigned i = cleanups.size(); i != 0; --i)
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