[Bug c++/83730] Unnecessary generation of guard variables with -fno-threadsafe-statics
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83730 Andrew Pinski changed: What|Removed |Added Resolution|--- |DUPLICATE Status|NEW |RESOLVED --- Comment #8 from Andrew Pinski --- Dup, and fixed already. *** This bug has been marked as a duplicate of bug 78940 ***
[Bug c++/83730] Unnecessary generation of guard variables with -fno-threadsafe-statics
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83730 --- Comment #7 from Jonathan Wakely --- As I noted at https://gcc.gnu.org/ml/gcc-help/2019-10/msg00038.html the guard variable is emitted, but appears to be unused when compiled with -fno-threadsafe-statics.
[Bug c++/83730] Unnecessary generation of guard variables with -fno-threadsafe-statics
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83730
--- Comment #6 from Wilhelm M ---
This is still true for local statics as shown below:
// Test für guard variable
struct A {
inline A(int v = 0) {} // without user-defined ctors, guards are omitted
int m1() const {
return m;
}
private:
int m = 0;
};
//namespace { // without anon-ns guards, are generated
template
struct X {
static int foo() {
static T m; // even as local-static and -fno-threadsafe-statics,
guards are generated
return m.m1();
}
//inline static T m;
};
//}
int main() {
return X::foo();
}
[Bug c++/83730] Unnecessary generation of guard variables with -fno-threadsafe-statics
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83730
--- Comment #5 from Wilhelm M ---
Only for completeness: if you write the following, no guards are produced:
struct A {
A() = default; // if commented out, no guards are allocated
void foo() {}
};
template
struct B {
static void foo() {
mTop.foo();
}
inline static T mTop{};
};
int main() {
B::foo();
}
So the c++14 an c++17 variants produce the same guards if
default-initialization is used. But produce no guards if value-initialization
ist used or the defaulted ctor is removed. Thats strange ...
[Bug c++/83730] Unnecessary generation of guard variables with -fno-threadsafe-statics
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83730
Wilhelm M changed:
What|Removed |Added
Keywords|wrong-code |
--- Comment #4 from Wilhelm M ---
If you change the example as below, you still get guards.
struct A {
A() = default;
void foo() {}
};
template
struct B {
static void foo() {
mTop.foo();
}
static T mTop;
};
template T B::mTop; // change
int main() {
B::foo();
}
[Bug c++/83730] Unnecessary generation of guard variables with -fno-threadsafe-statics
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83730
Jonathan Wakely changed:
What|Removed |Added
Keywords||wrong-code
Target|avr |
Status|UNCONFIRMED |NEW
Last reconfirmed||2018-01-08
Ever confirmed|0 |1
--- Comment #3 from Jonathan Wakely ---
This happens on all targets, but only for a C++17 inline static member
variable.
There's no guard variable for the C++14 equivalent:
struct A {
A() = default;
void foo() {}
};
template
struct B {
static void foo() {
mTop.foo();
}
static T mTop;
};
template T B::mTop{};
int main() {
B::foo();
}
[Bug c++/83730] Unnecessary generation of guard variables with -fno-threadsafe-statics
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83730 --- Comment #2 from Wilhelm M --- Additionally: if one only uses a global variable of type A, no guards are creates at all. But this should be conceptually equivalent to the above use case.
[Bug c++/83730] Unnecessary generation of guard variables with -fno-threadsafe-statics
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83730 --- Comment #1 from Wilhelm M --- If the defaulted ctor is commented out, the guards aren't generated. Still is even stranger ...
