bug#52376: 28.0.90; libdir is missing from native-comp-eln-load-path with GTK3 build

[Bhavin Gandhi]

On Fri, 10 Dec 2021 at 01:44, Andrea Corallo <akrl@sdf.org> wrote:
> >> I suggest to set a breakpoint at pdumper.c:5321 and print 'fndata' to
> >> see where we do expect to find the installed eln we don't find.
> >
> > It did not reach that breakpoint, and Emacs just started as usual. Seems
> > like the RELOC_NATIVE_COMP_UNIT case is not getting matched.
>
> Actually this is very bizarre.  A native compiled Emacs that has been
> dumped has to go through there to startup so either:
>
> 1- we are debugging temacs and non emacs
> 2- emacs was compiled with native compilation
> 3- the breakpoint is not working as expected, maybe because it's an
> optimized build.
>
> I guess most likely we are looking at case 3 here.  Could you try in
> this case building pdumper.c (or all Emacs) with -O0 -g3?

Emacs was indeed compiled with -O0 -g3, but to rule out that possibility,
I compiled it again with these two flags. And still it is showing same
behaviour, it goes ahead without stopping at the breakpoint.

> Just to be 100% sure, one mine src/pdumper.c. from emacs28 line 5321 is:
>
>            if (file_access_p (fndata, F_OK))

In my case that line is at pdumper.c:5319

When I test the same breakpoint with the Lucid build I get the
following, it is able to find the correct paths here.

--8<---------------cut here---------------start------------->8---
$ gdb  --args /usr/bin/emacs-28.0.90-lucid -Q
Reading symbols from /usr/bin/emacs-28.0.90-lucid...
Reading symbols from
/usr/lib/debug/usr/bin/emacs-28.0.90-lucid-28.0.90-1.fc35.x86_64.debug...
(gdb) break pdumper.c:5319
Breakpoint 3 at 0x692487: file ../../src/pdumper.c, line 5319.
(gdb) run
Starting program: /usr/bin/emacs-28.0.90-lucid -Q

Breakpoint 3, dump_do_dump_relocation (dump_base=140737265905664,
reloc=...) at ../../src/pdumper.c:5319
5319            if (file_access_p (fndata, F_OK))
(gdb) p *comp_u
$3 = {
  header = {
    size = 4611686018830053383
  },
  file = XIL(0x7ffff3295623),
  optimize_qualities = XIL(0x7ffff3295593),
  lambda_gc_guard_h = XIL(0xe4d5f5),
  lambda_c_name_idx_h = XIL(0x7ffff3292625),
  data_fdoc_v = XIL(0),
  data_vec = XIL(0x7ffff328dc4d),
  data_impure_vec = XIL(0x7ffff2beb415),
  data_imp_relocs = 0x0,
  loaded_once = false,
  load_ongoing = false,
  handle = 0x0
}
(gdb) p comp_u->file
$4 = XIL(0x7ffff3295623)
(gdb) pr
("../lib64/emacs/28.0.90/native-lisp/28.0.90-be2fc0ab/preloaded/window-0d1b8b93-41a00537.eln"
. "../native-lisp/28.0.90-be2fc0ab/preloaded/window-0d1b8b93-41a00537.eln")
(gdb) p cu_file1
$5 = XIL(0x7ffff3295654)
(gdb) pr
"../lib64/emacs/28.0.90/native-lisp/28.0.90-be2fc0ab/preloaded/window-0d1b8b93-41a00537.eln"
(gdb) p cu_file2
$6 = XIL(0x7ffff3295634)
(gdb) pr
"../native-lisp/28.0.90-be2fc0ab/preloaded/window-0d1b8b93-41a00537.eln"
 --8<---------------cut here---------------end--------------->8---

>From the GTK3 build:

Configured using:
 'configure --build=x86_64-redhat-linux-gnu
 --host=x86_64-redhat-linux-gnu --program-prefix=
 --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
 --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
 --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
 --libexecdir=/usr/libexec --localstatedir=/var
 --sharedstatedir=/var/lib --mandir=/usr/share/man
 --infodir=/usr/share/info --with-dbus --with-gif --with-jpeg --with-png
 --with-rsvg --with-tiff --with-xft --with-xpm --with-x-toolkit=gtk3
 --with-gpm=no --with-xwidgets --with-modules --with-harfbuzz
 --with-cairo --with-json --with-native-compilation
 --enable-checking=yes,glyphs --enable-check-lisp-object-type
 build_alias=x86_64-redhat-linux-gnu host_alias=x86_64-redhat-linux-gnu
 CC=gcc 'CFLAGS=-DMAIL_USE_LOCKF -flto=auto -ffat-lto-objects
 -fexceptions -grecord-gcc-switches -pipe -Wall -Werror=format-security
 -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS
 -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong
 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic
 -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection
 -O0 -g3' LDFLAGS=-Wl,-z,relro
 PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'


>From the Lucid build:
Configured using:
 'configure --build=x86_64-redhat-linux-gnu
 --host=x86_64-redhat-linux-gnu --program-prefix=
 --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
 --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
 --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
 --libexecdir=/usr/libexec --localstatedir=/var
 --sharedstatedir=/var/lib --mandir=/usr/share/man
 --infodir=/usr/share/info --with-dbus --with-gif --with-jpeg --with-png
 --with-rsvg --with-tiff --with-xft --with-xpm --with-x-toolkit=lucid
 --with-gpm=no --with-modules --with-harfbuzz --with-cairo --with-json
 --with-native-compilation build_alias=x86_64-redhat-linux-gnu
 host_alias=x86_64-redhat-linux-gnu CC=gcc 'CFLAGS=-DMAIL_USE_LOCKF -O2
 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches
 -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2
 -Wp,-D_GLIBCXX_ASSERTIONS
 -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong
 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic
 -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection'
 LDFLAGS=-Wl,-z,relro
 PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'