1364597 - link fails with GCC 7.1

Status: RESOLVED WORKSFORME

(Core :: General, defect)

Description

[:aceman]

I tried GCC 7.1 on Linux now and linking of libxul fails for me with errors like these: 
toolkit/library/../../gfx/skia/GrGLBuffer.o(.debug_addr+0x4a0): error: undefined reference to 'GrFragmentProcessor::coordTransform(int) const''
toolkit/library/../../dom/canvas/Unified_cpp_dom_canvas3.o(.debug_addr+0x52c8): error: undefined reference to 'gfxPrefs::GetAPZEnlargeDisplayPortWhenClippedPrefName()'

Similar errors repeat multiple times for many object files.

On the same tree, when I went back to GCC 5.4 the build+link works fine again.

Is there some change in symbol visibility with GCC 7?

Comment 1

[Sylvestre Ledru [:Sylvestre]]

I don't experience this issue. Which distro do you use ?

Comment 2

[:aceman]

Slackware. Which aims to keep packages close to upstream without modifications.
It introduced gcc 7.1 in the -current branch ('unstable/nightly') so I tried it as a drop in replacement for gcc 5.4. Going back to 5.4 after that makes the error go away again.

Comment 3

[:aceman]

This still happens. It happens regardless whether I use ld.bfd or gold linker.

I'm using these gcc flags:
export CFLAGS="-march=native -ggdb -gsplit-dwarf -O2 -fstack-protector-strong -fno-lto -fno-fat-lto-objects -fno-ipa-icf"

Interestingly, the main app binary is created fine, it is just libxul.so that fails to link.

Comment 4

[:aceman]

It appears others have also observed this problem so it is not only my system (it still may be distro specific).
See http://www.slackware.com/~alien/slackbuilds/ChangeLog.txt:
Wed Jun 21 17:29:12 UTC 2017
gcc5: added a package for gcc-5.4.0 which can be installed alongside
  the gcc-7.1.0 of Slackware-current.  Some applications will not compile
  with gcc7 (like Pale Moon) so in those cases, install gcc5 on the side.

I assume Pale Moon being based on Firefox code may indicate something.

Comment 5

[nulldomain]

I'm also see a failure during linking with gcc 7.1.0 (whether it's using bfd or gold linker), but only when doing a PGO build.  Firefox builds fine without PGO.  I'm using default optimizations with no extra CFLAGS.  This is the error I get with gold: 

../../build/unix/gold/ld: error: /home/user/desktop-src/applications/firefox-build/toolkit/library/../../gfx/thebes/Unified_cpp_gfx_thebes1.o: requires dynamic R_X86_64_PC32 reloc against '_ZN7gfxFont13GetShapedWordIhEEP13gfxShapedWordPN7mozilla3gfx10DrawTargetEPKT_jjNS3_7unicode6ScriptEbiNS4_15ShapedTextFlagsEN13gfxFontShaper13RoundingFlagsEP18gfxTextPerfMetrics' which may overflow at runtime; recompile with -fPIC
../../build/unix/gold/ld: error: read-only segment has dynamic relocations
/home/user/desktop-src/applications/firefox-55.0.1/gfx/thebes/gfxTextRun.cpp:1627: error: undefined reference to 'gfxShapedWord* gfxFont::GetShapedWord<unsigned char>(mozilla::gfx::DrawTarget*, unsigned char const*, unsigned int, unsigned int, mozilla::unicode::Script, bool, int, mozilla::gfx::ShapedTextFlags, gfxFontShaper::RoundingFlags, gfxTextPerfMetrics*)'
collect2: error: ld returned 1 exit status

Comment 6

[nulldomain]

I can build Firefox 57.0 fine now with PGO on gcc 7.2.0.  One thing I have to do to build stylo to make it find system headers for nspr and pixman is set BINDGEN_CFLAGS=$(pkg-config --cflags nspr pixman-1).

Comment 7

[:aceman]

It seems this is fixed for me with the recent gcc 7.3 release. I get successful builds now.
Possibly fixed by https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81993 (I do use -gsplit-dwarf as stated in comment 3).

Comment 8

[Sylvestre Ledru [:Sylvestre]]

I wasn't expecting this bug on gcc to affect also firefox devs ;)