3e25ae605e
Previously, Itanium ABI guard variables were set after initialization was
complete for non-block declared variables with static and thread storage
duration. That resulted in initialization of such variables being restarted
in cases where the variable was referenced while it was still under
construction. Per C++20 [class.cdtor]p2, such references are permitted
(though the value obtained by such an access is unspecified). The late
initialization resulted in recursive reinitialization loops for cases like
this:
template<typename T>
struct ct {
struct mc {
mc() { ct<T>::smf(); }
void mf() const {}
};
thread_local static mc tlsdm;
static void smf() { tlsdm.mf(); }
};
template<typename T>
thread_local typename ct<T>::mc ct<T>::tlsdm;
int main() {
ct<int>::smf();
}
With this change, guard variables are set before initialization is started
so as to avoid such reinitialization loops.
Fixes https://github.com/llvm/llvm-project/issues/57828
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D135919
49 lines
1.8 KiB
C++
49 lines
1.8 KiB
C++
// RUN: %clang_cc1 -std=c++1y -triple x86_64-linux-gnu -emit-llvm -o - %s | FileCheck %s
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// Check that we keep the 'extern' when we instantiate the definition of this
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// variable template specialization.
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template<typename T> extern const int extern_redecl;
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template<typename T> const int extern_redecl = 5;
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template const int extern_redecl<int>;
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// CHECK: @_Z13extern_redeclIiE = weak_odr constant
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template<typename T> struct Outer {
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template<typename U> struct Inner {
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template<typename V> static int arr[];
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};
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};
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Outer<char[100]> outer_int;
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int init_arr();
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template<typename T> template<typename U> template<typename V> int Outer<T>::Inner<U>::arr[sizeof(T) + sizeof(U) + sizeof(V)] = { init_arr() };
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int *p = Outer<char[100]>::Inner<char[20]>::arr<char[3]>;
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namespace PR35456 {
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// CHECK: @_ZN7PR354561nILi0EEE = linkonce_odr global i32 0
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template<int> int n;
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int *p = &n<0>;
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}
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// CHECK: @_ZN5OuterIA100_cE5InnerIA20_cE3arrIA3_cEE = linkonce_odr global [123 x i32] zeroinitializer
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// CHECK: @_ZGVN5OuterIA100_cE5InnerIA20_cE3arrIA3_cEE = linkonce_odr global
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// CHECK: @_ZTHN7PR4211112_GLOBAL__N_11nILi0EEE = internal alias {{.*}} @[[PR42111_CTOR:.*]]
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// CHECK: call {{.*}}@_Z8init_arrv
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// Ensure that we use guarded initialization for an instantiated thread_local
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// variable with internal linkage.
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namespace PR42111 {
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int f();
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namespace { template <int = 0> thread_local int n = f(); }
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// CHECK: define {{.*}}@[[PR42111_CTOR]](
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// CHECK: load {{.*}} @_ZGVN7PR4211112_GLOBAL__N_11nILi0EEE
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// CHECK: icmp eq i8 {{.*}}, 0
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// CHECK: br i1
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// CHECK: store i8 1, ptr @_ZGVN7PR4211112_GLOBAL__N_11nILi0EEE
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// CHECK: call noundef i32 @_ZN7PR421111fEv(
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// CHECK: [[N_ADDR:%.+]] = call align 4 ptr @llvm.threadlocal.address.p0(ptr align 4 @_ZN7PR4211112_GLOBAL__N_11nILi0EEE)
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// CHECK: store i32 {{.*}}, ptr [[N_ADDR]]
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int g() { return n<> + n<>; }
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}
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