From: Matt <matt@use.net>
To: Ian Lance Taylor <iant@google.com>
Cc: gcc-help@gcc.gnu.org
Subject: Re: bootstrap comparison failure with bootstrap-lto
Date: Fri, 18 Nov 2011 06:35:00 -0000 [thread overview]
Message-ID: <Pine.NEB.4.64.1111171544560.23588@cesium.clock.org> (raw)
In-Reply-To: <mcr8vnfvil6.fsf@dhcp-172-18-216-180.mtv.corp.google.com>
On Wed, 16 Nov 2011, Ian Lance Taylor wrote:
> Matt <matt@use.net> writes:
>
>> On Mon, 14 Nov 2011, Ian Lance Taylor wrote:
>>
>>> Matt <matt@use.net> writes:
>>>
>>>> libcpp/lex.o differs
>>>
>>> What are the differences between stage2-libcpp/lex.o and
>>> stage3-libcpp/lex.o? Ignore the fact that one will have debug info and
>>> the other will not. Look at the readelf -S output for both files, and
>>> see if there are any differences in sections whose names do not start
>>> with ".debug".
>>
>> in stage2-libcpp/lex.o:
>> [79] .init_array INIT_ARRAY 0000000000000000 00021280
>> 0000000000000008 0000000000000000 WA 0 0 8
>> [80] .rela.init_array RELA 0000000000000000 0003a8e8
>> 0000000000000018 0000000000000018 101 79 8
>>
>>
>>
>> in stage3-libcpp/lex.o:
>> [79] .ctors PROGBITS 0000000000000000 00021280
>> 0000000000000008 0000000000000000 WA 0 0 8
>> [80] .rela.ctors RELA 0000000000000000 0003a8e0
>> 0000000000000018 0000000000000018 101 79 8
>>
> Thanks. It appears that for some reason your stage2 build is using
> --enable-initfini-array while your stage3 build is using
> --disable-initfini-array. The default value for this configure option
> is set by the configure script.
>
> grep for gcc_cv_initfini_array in stage1-gcc/config.log and
> stage2-gcc/config.log. I am guessing that they will have different
> values.
yup. stage1 succeeds and stage2 fails, as you predicted.
> Look in stage1-gcc/config.log and stage2-gcc/config.log. Look for
> "checking for .preinit_array/.init_array/.fini_array support". It
> should be followed by a compile and run of conftest. I'm guessing that
> one of those runs succeeded and one failed. See if config.log says why.
It *kind of* says why. I've pasted the output below. Unfortunately, when
the full build is finished, the prev-gcc/xgcc no longer exists. When I
test the conftest.c (copied and pasted from the log), the stage1-gcc/xgcc
and stage2-gcc/xgcc have no problem with it (of course).
I did run valgrind on stage1's xgcc and stage2's xgcc, but the only thing
interesting I saw was some branching on unconditional values from data fed
to libz via lto.c:
==9766== Conditional jump or move depends on uninitialised value(s)
==9766== at 0x7035510: inflateReset2 (in
/lib/x86_64-linux-gnu/libz.so.1.2.3.4)
==9766== by 0x7035605: inflateInit2_ (in
/lib/x86_64-linux-gnu/libz.so.1.2.3.4)
==9766== by 0x12C0805: lto_end_uncompression (lto-compress.c:277)
==9766== by 0x1223FBF: lto_get_section_data (lto-section-in.c:172)
==9766== by 0x507019: lto_file_finalize (lto.c:1134)
==9766== by 0x5070A6: lto_create_files_from_ids (lto.c:1150)
==9766== by 0x5071BF: lto_file_read (lto.c:1190)
Regardless, here's the output. I'll try another build and "catch" the
build before it removes the prev-gcc/xgcc and try to reproduce the error
there. If you have some ideas in the meantime, let me know.
configure:10965: checking for .preinit_array/.init_array/.fini_array
support
configure:11084: /home/matt/src/gcc-trunk/obj/./prev-gcc/xgcc
-B/home/matt/src/gcc-trunk/obj/./prev-gcc/
-B/home/matt/x86_64-unknown-linux-gnu/bin/
-B/home/matt/x86_64-unknown-linux-gnu/bin/
-B/home/matt/x86_64-unknown-linux-gnu/lib/ -isystem
/home/matt/x86_64-unknown-linux-gnu/include -isystem
/home/matt/x86_64-unknown-linux-gnu/sys-include -o conftest -g -O2
-flto=jobserver -frandom-seed=1 -static-libstdc++ -static-libgcc
conftest.c >&5
configure:11084: $? = 0
configure:11084: ./conftest
/home/matt/src/gcc-trunk/gcc/configure: line 1997: 4819 Aborted
./conftest$ac_exeext
configure:11084: $? = 134
configure: program exited with status 134
configure: failed program was:
[...]
PS: I imagine anyone with an Ubuntu 11.10/amd64 installation (or something
similar) would have the same issue. I'll try and reproduce on 11.04 and a
fresh 11.10, as I have time, as well.
--
tangled strands of DNA explain the way that I behave.
http://www.clock.org/~matt
next prev parent reply other threads:[~2011-11-17 23:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-14 22:23 Matt
2011-11-15 5:56 ` Ian Lance Taylor
2011-11-16 21:55 ` Matt
2011-11-17 5:43 ` Ian Lance Taylor
2011-11-18 6:35 ` Matt [this message]
2011-11-18 13:47 ` Ian Lance Taylor
2011-11-18 21:08 ` Matt
2011-11-19 1:11 ` Ian Lance Taylor
2011-11-19 2:41 ` Matt
2011-11-19 15:37 ` Ian Lance Taylor
2011-11-20 6:51 ` Matt
2011-11-20 7:32 ` Ian Lance Taylor
2011-11-20 20:23 ` Matt Hargett
2011-11-21 17:27 ` Ian Lance Taylor
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