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#define ANNOTATE(property) __attribute__((tag(property)))
struct Cell { int f; } ANNOTATE("GC Thing");
extern void GC() ANNOTATE("GC Call");
void GC()
{
// If the implementation is too trivial, the function body won't be emitted at all.
asm("");
}
class RAII_GC {
public:
RAII_GC() {}
~RAII_GC() { GC(); }
};
// ~AutoSomething calls GC because of the RAII_GC field. The constructor,
// though, should *not* GC -- unless it throws an exception. Which is not
// possible when compiled with -fno-exceptions.
class AutoSomething {
RAII_GC gc;
public:
AutoSomething() : gc() {
asm(""); // Ooh, scary, this might throw an exception
}
~AutoSomething() {
asm("");
}
};
extern void usevar(Cell* cell);
void f() {
Cell* thing = nullptr; // Live range starts here
{
AutoSomething smth; // Constructor can GC only if exceptions are enabled
usevar(thing); // Live range ends here
} // In particular, 'thing' is dead at the destructor, so no hazard
}
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