Re: ipa-icf::merge TLC

[Christophe Lyon <christophe.lyon@linaro.org>]

On 2 March 2015 at 21:21, Jan Hubicka <hubicka@ucw.cz> wrote:
>>
>>
>> On 01/03/15 16:47, Christophe Lyon wrote:
>> >On 27 February 2015 at 21:49, Jan Hubicka <hubicka@ucw.cz> wrote:
>> >>>
>> >>>../sysdeps/gnu/siglist.c:72:1: internal compiler error: in address_matters_p, at symtab.c:1908
>> >>>  versioned_symbol (libc, __new_sys_sigabbrev, sys_sigabbrev, GLIBC_2_3_3);
>> >>>  ^
>> >>>0x66a080 symtab_node::address_matters_p()
>> >>>         /scratch/sellcey/repos/bootstrap/src/gcc/gcc/symtab.c:1908
>> >>>0xe7cbe5 ipa_icf::sem_variable::merge(ipa_icf::sem_item*)
>> >>>         /scratch/sellcey/repos/bootstrap/src/gcc/gcc/ipa-icf.c:1443
>> >>
>> >>Indeed, the ipa-icf should not try to analyze aliases - just prove ekvialence of
>> >>definitions they are attached to.  It already does that for functions (bit by accident;
>> >>it gives up when there is no gimple body), but it does not do that for variables because
>> >>it gets into ctor_for_folding. For that reason it sometimes decides to try to make two
>> >>variable aliases alias of each other that is not a good idea, because of possible creation
>> >>of loops.
>> >>
>> >>I am just discussing with Martin the fix.
>> >>
>> >>Honza
>> >
>> >For the record, I have noticed similar errors on ARM and AArch64
>> >targets, when building glibc.
>> >
>> >Christophe.
>> >
>>
>> I confirm ARM and AArch64 failing to build with this patch:
>> chmod a-w /work/build-aarch64-none-linux-gnu/obj/glibc/stdio-common/errlist-compat.cT
>> 0x6b9100 symtab_node::address_matters_p()
>>       /work/src/gcc/gcc/symtab.c:1908
>> 0xedb4e5 ipa_icf::sem_variable::merge(ipa_icf::sem_item*)
>>       /work/src/gcc/gcc/ipa-icf.c:1723
>> 0xee03f9 ipa_icf::sem_item_optimizer::merge_classes(unsigned int)
>>       /work/src/gcc/gcc/ipa-icf.c:2955
>> 0xee6d31 ipa_icf::sem_item_optimizer::execute()
>>       /work/src/gcc/gcc/ipa-icf.c:2217
>> 0xee8df1 ipa_icf_driver
>>       /work/src/gcc/gcc/ipa-icf.c:3034
>> 0xee8df1 ipa_icf::pass_ipa_icf::execute(function*)
>>       /work/src/gcc/gcc/ipa-icf.c:3081
>
> I commited patch for the alias merging yesterda night, so it should be fixed
> now.  If it still fails, please fill in a PR with preprocessed testcase so I
> can reproduce it in a cross.
>

On my side, I saw builds complete again starting with r221090, I guess
that's the commit you are referring to?

Thanks,

Christophe.

> Honza
>> Please submit a full bug report,
>> with preprocessed source if appropriate.
>> Please include the complete backtrace with any bug report.
>> See <http://gcc.gnu.org/bugs.html> for instructions.
>> make[2]: ***
>> [/work/build-aarch64-none-linux-gnu/obj/glibc/stdio-common/siglist.o]
>> Error 1
>> make[2]: *** Waiting for unfinished jobs....
>> mv -f /work/build-aarch64-none-linux-gnu/obj/glibc/stdio-common/errlist-compat.cT /work/build-aarch64-none-linux-gnu/obj/glibc/stdio-common/errlist-compat.c
>>
>> Regards,
>> Alex