Bug#491137: [g++/s390 only] optimization causes errornous behavior

[Michael Tautschnig]

Package: g++-4.3
Version: 4.3.1-4

[I leave it to the gcc maintainers to judge about the severity, because it
actually breaks otherwise running programs, but those cases seem extremely rare]

When rebuilding diagnostics, it failed on s390 during the selftests [0]. The
failing piece of code is attached. This is not actually a tiny example, but all
attempts of reducing this further failed to reproduce the error. This is a
regression because it does not fail on g++-4.2. The compiler command lines to
reproduce are:

g++ -O -fgcse -DDEBUG__LEVEL__=2 invariance_annotation.t.cpp -ldiagnostics -o 
invbuggy
./invbuggy run "/*" 2

whereat we would expect to see no failure, instead of a MISSING_EXCEPTION [TES]:
...

Please note that replacing -O by
-fomit-frame-pointer \
-fauto-inc-dec \
-fcprop-registers \
-fdce \
-fdefer-pop \
-fdelayed-branch \
-fdse \
-fguess-branch-probability \
-fif-conversion2 \
-fif-conversion \
-finline-small-functions \
-fipa-pure-const \
-fipa-reference \
-fmerge-constants \
-fsplit-wide-types \
-ftree-ccp \
-ftree-ch \
-ftree-copyrename \
-ftree-dce \
-ftree-dominator-opts \
-ftree-dse \
-ftree-fre \
-ftree-sra \
-ftree-ter \
-funit-at-a-time
 
(all controllable options enabled by -O) does _not_ yield the errornous
behavior, and dropping -fgcse also stops the runtime failure.

Attached please find the cleaned source file.  All attempts of reproducing the
error were made on raptor.d.o. If there is anything more that I could do to
debug this issue, please contact me.

Best,
Michael

[0] 
http://buildd.debian.org/fetch.cgi?&pkg=diagnostics&ver=0.2.2%2Bb1&arch=s390&stamp=1214648343&file=log



#include <diagnostics/unittest.hpp>

// component
#include <diagnostics/macros/invariance_annotation.hpp>

#define TEST_COMPONENT_NAME invariance_annotation
#define TEST_COMPONENT_NAMESPACE diagnostics


DIAGNOSTICS_NAMESPACE_BEGIN;
TEST_NAMESPACE_BEGIN;
TEST_COMPONENT_TEST_NAMESPACE_BEGIN;
using namespace unittest;

class Dummy_Class_With_Invariance
{
    typedef Dummy_Class_With_Invariance Self;
public:
    Dummy_Class_With_Invariance() 
        : m_class_invariance_called(0),
          m_throw(false)
    {
    }

    void method_with_guard(bool const t1, 
                           bool const t2)
    {
        m_class_invariance_called=0;
        m_throw=t1;
        ::diagnostics::internal::Class_Invariance_Guard_Throw<Self> g(this); 
        m_throw=t2;
    }
    

    void m_class_invariance() const
    {
        ++m_class_invariance_called;
        if(m_throw) throw Test_Exception("Invariance throwing");
    }

    int class_invariance_called() const
    {
        return m_class_invariance_called;
    }
    
private:
    mutable int m_class_invariance_called;

    bool m_throw;
};


void guard(Test_Data & data)
{
    Dummy_Class_With_Invariance d;

    TEST_EXCEPTIONLESS_BLOCK_ENTER;
    d.method_with_guard(false,false);
    TEST_EXCEPTIONLESS_BLOCK_EXIT;
    TEST_ASSERT(d.class_invariance_called()==2);
    
    TEST_THROWING_BLOCK_ENTER;
    d.method_with_guard(true,true);
    TEST_THROWING_BLOCK_EXIT1(Test_Exception,::std::string("Invariance 
throwing").c_str());
    TEST_ASSERT(d.class_invariance_called()==1);

    TEST_THROWING_BLOCK_ENTER;
    d.method_with_guard(false,true);
    TEST_THROWING_BLOCK_EXIT1(Test_Exception,::std::string("Invariance 
throwing").c_str());
    TEST_ASSERT(d.class_invariance_called()==2);

}

TEST_COMPONENT_TEST_NAMESPACE_END;
TEST_NAMESPACE_END;
DIAGNOSTICS_NAMESPACE_END;

TEST_SUITE_BEGIN;
TEST_NORMAL_CASE(&guard,LEVEL_PROD);
TEST_SUITE_END;

STREAM_TEST_SYSTEM_MAIN;

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