[debbugs-tracker] bug#28213: closed ([bootstrap] Error 2 with -Os with gcc (GCC) 7.1.1)

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Your message dated Tue, 29 Aug 2017 15:07:29 -0700
with message-id <address@hidden>
and subject line Re: [bootstrap] Error 2 with -Os with gcc (GCC) 7.1.1
has caused the debbugs.gnu.org bug report #28213,
regarding [bootstrap] Error 2 with -Os with gcc (GCC) 7.1.1
to be marked as done.

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28213: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=28213
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> --- Begin Message ---
>
>
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> Subject: 
>
> [bootstrap] Error 2 with -Os with gcc (GCC) 7.1.1
>
>
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> Date: 
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> 24 Aug 2017 07:38:15 -0000
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>
> Hi,
>
> CFLAGS="-march=native -ffast-math -Os"
> -Os fails with gcc(GCC) 7.1.1 20170622 (Red Hat 7.1.1-3)
> sed -i 's/Os/O3/g' build or any other -Ox (unlike -Os)
> works.
>      ./configure                               \
>             --prefix=$deploy_folder               \
>             --sysconfdir=$sysconfdir              \
>             --enable-locallisppath=$locallisppath \
>             --libexecdir=$libexecdir              \
>             --localstatedir=$localstatedir        \
>             --enable-largefile                    \
>             --with-x-toolkit=gtk3                 \
>             --with-sound=yes                      \
>             --with-modules                        \
>             --with-xwidgets                       \
>             --without-pop                         \
>             --with-file-notification=yes          \
>             --enable-link-time-optimization
>
>
> Dumping under the name emacs
> 10678816 of 33554432 static heap bytes used
> 2437614 pure bytes used
> Adding name emacs-26.0.50.1
> ln -f emacs bootstrap-emacs
> make[2]: Leaving directory '/usr/local/src/sdm/emacs/trunk/src'
> make -C lisp all
> make[2]: Entering directory '/usr/local/src/sdm/emacs/trunk/lisp'
> make -C ../leim all EMACS="../src/emacs"
> make[3]: Entering directory '/usr/local/src/sdm/emacs/trunk/leim'
> make[3]: Nothing to be done for 'all'.
> make[3]: Leaving directory '/usr/local/src/sdm/emacs/trunk/leim'
> make -C ../admin/grammars all EMACS="../../src/emacs"
> make[3]: Entering directory '/usr/local/src/sdm/emacs/trunk/admin/grammars'
> make[3]: Nothing to be done for 'all'.
> make[3]: Leaving directory '/usr/local/src/sdm/emacs/trunk/admin/grammars'
> make[3]: Entering directory '/usr/local/src/sdm/emacs/trunk/lisp'
>   ELC      align.elc
>   ELC      allout.elc
> Eager macro-expansion failure: (invalid-function [])
> Eager macro-expansion failure: (invalid-function [])
> Eager macro-expansion failure: (invalid-function [])
> >>Error occurred processing allout.el: Invalid function (([]))
> make[3]: *** [Makefile:297: allout.elc] Error 1
> make[3]: Leaving directory '/usr/local/src/sdm/emacs/trunk/lisp'
> make[2]: *** [Makefile:320: compile-main] Error 2
> make[2]: Leaving directory '/usr/local/src/sdm/emacs/trunk/lisp'
> make[1]: *** [Makefile:403: lisp] Error 2
> make[1]: Leaving directory '/usr/local/src/sdm/emacs/trunk'
> make: *** [Makefile:1099: bootstrap] Error 2
>
>  
>
> --- End Message ---

--- Begin Message --- Subject: Re: [bootstrap] Error 2 with -Os with gcc (GCC) 7.1.1 Date: Tue, 29 Aug 2017 15:07:29 -0700 User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 Thanks for the bug report, which led to an entertaining and hair-raising trip through Emacs's garbage collector and let me brush up on my machine-level debugging skills. I installed the attached patches, which fix the problem for me, and I am closing the bug.

This bug report underscores that --enable-link-time-optimization is experimental and should not yet be recommended for production use with Emacs. When used, even with the attached patches I can easily get Emacs to dump core by exploiting bugs in GCC's code generator. The commit message in the last of the attached patches contains more detail about this.

0001-Align-stack-bottom-properly.patch
Description: Text Data

0002-Improve-stack-top-heuristic.patch
Description: Text Data

0003-Make-garbage-collection-more-conservative.patch
Description: Text Data

0004-Be-more-conservative-in-link-time-optimization-doc.patch
Description: Text Data

--- End Message ---