Attachment 704602 Details for Bug 917378 – minimal example

minimal example

gcc-4.1.2-O2-bug.cc (text/plain), 1.39 KB, created by Kamil Dudka on 2013-03-03 17:26:45 UTC

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Creator: Kamil Dudka

Created: 2013-03-03 17:26:45 UTC

Size: 1.39 KB

patch

obsolete

>#if 0
>set -x
>g++ $0 -g -O2 -DWORK_AROUND_OPTIMIZATION_BUG && valgrind ./a.out
>g++ $0 -g -O2 && valgrind ./a.out
>exit $?
>#endif
>
>#include <vector>
>
>struct RefCnt {
>    int cnt_;
>
>    RefCnt(): cnt_(1) { }
>
>    bool /* needCloning */ enter() {
>        ++cnt_;
>        return false;
>    }
>
>    bool /* wasLast */ leave() {
>        return !(--cnt_);
>    }
>};
>
>struct RefCntLib {
>    template <class T> static void enter(T *&ptr) {
>        if (ptr->refCnt.enter())
>            ptr = new T(*ptr);
>    }
>
>    template <class T> static void leave(T *&ptr) {
>        if (ptr->refCnt.leave())
>            delete ptr;
>
>        ptr = 0;
>    }
>};
>
>struct RefItem {
>    RefCnt refCnt;
>};
>
>struct RStore {
>    typedef std::vector<RefItem *> T;
>    T ents_;
>
>    ~RStore() {
>        // NOTE: this never iterates because ents_ is always empty
>        for (T::iterator it = ents_.begin(); it != ents_.end(); ++it)
>            RefCntLib::leave(*it);
>    }
>};
>
>struct RClass {
>    RClass(): d(new Private) { }
>
>    ~RClass() {
>        RefCntLib::leave(d);
>    }
>
>    RClass& operator=(const RClass &);
>
>    struct Private {
>        RefCnt refCnt;
>        RStore rStore;
>    } *d;
>};
>
>RClass& RClass::operator=(const RClass &ref)
>{
>    RefCntLib::leave(d);
>    d = ref.d;
>#ifdef WORK_AROUND_OPTIMIZATION_BUG
>    asm volatile("" ::: "memory");
>#endif
>    RefCntLib::enter(d);
>    return *this;
>}
>
>int main()
>{
>    RClass rc1, rc2;
>    rc1 = rc2;
>}

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Attachments on bug 917378: 704602