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Re: Gold Patch to fix ICF bug.
On Fri, Apr 23, 2010 at 10:41 AM, Ian Lance Taylor <iant@google.com> wrote:
> Sriraman Tallam <tmsriram@google.com> writes:
>
>>> When I look at this test I don't understand what it is testing. ?It
>>> seems like the program is always going to run successfully, and you
>>> aren't testing anything else here. ?What is the point of this test?
>>
>> In this test, fn1 is folded into fn2 but still the linker must
>> generate a dynamic relocation for the vtable entry for fn1 as it is a
>> pie executable and fn1 is virtual. Otherwise, the program segfaults. I
>> am simply testing this. Is this alright ? I had
>> icf_virtual_function_folding_test run using a shell script before and
>> I realized that was not necessary.
>
> If it segfaults before your patch and stops segfaulting after your
> patch then this test is fine. ?I guess I don't yet see why it
> segfaults before your patch, but I haven't tried running it myself.
Yes, this was the test case used to expose the bug. Not checking for
section folding was causing the linker to omit the dynamic reloc
corresponding to fn1 and this caused the virtual call to crash as it
was not dynamically relocated.
>
> Ian
>