[Bug c++/67834] New: [5 Regression] Local references inside comdat groups

[Bug c++/67834] New: [5 Regression] Local references inside comdat groups

[danglin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67834

            Bug ID: 67834
           Summary: [5 Regression] Local references inside comdat groups
           Product: gcc
           Version: 5.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: danglin at gcc dot gnu.org
  Target Milestone: ---
              Host: hppa-unknown-linux-gnu
            Target: hppa-unknown-linux-gnu
             Build: hppa-unknown-linux-gnu

Created attachment 36442
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36442&action=edit
Preprocessed source

With the switch to gcc-5 on Debian, we are seeing a number of c++ packages
fail to build with the following error:

_ZXXX referenced in section `.data.rel.ro.local' of YYY: defined in discarded
section `.text._ZXXX

Here is the assembler code for _ZN3uhd9transport3sphL19handle_overflow_nopEv:

       .section       
.text._ZN3uhd9transport3sphL19handle_overflow_nopEv,"axG",@progbits,_ZN3uhd9transport3sph19recv_packet_handler6resizeEj,comdat
       .align 4        .type   _ZN3uhd9transport3sphL19handle_overflow_nopEv,
@function
.LFB8296:
       .file 6
"/home/dave/debian/uhd/uhd-3.9.1/host/lib/usrp/usrp1/../../transport/super_recv_packet_handler.hpp"
       .loc 6 61 0
       .cfi_startproc
_ZN3uhd9transport3sphL19handle_overflow_nopEv:
       .PROC
       .CALLINFO FRAME=0,NO_CALLS
       .ENTRY
       bv,n %r0(%r2)
       .EXIT
       .PROCEND        .cfi_endproc
.LFE8296:
       .size   _ZN3uhd9transport3sphL19handle_overflow_nopEv,
.-_ZN3uhd9transport3sphL19handle_overflow_nopEv

Subsequently, there is a reference from a plabel in .data.rel.ro.local:

       .section        .data.rel.ro.local
       .align 4
.LC135:
       .word   P%_ZN3uhd9transport3sphL19handle_overflow_nopEv

COMDAT group section [   10] `.group'
[_ZN3uhd9transport3sph19recv_packet_handler6resizeEj] contains 2 sections:
   [Index]    Name
   [  581]   .text._ZN3uhd9transport3sphL19handle_overflow_nopEv
   [ 1282]   .text._ZN3uhd9transport3sph19recv_packet_handler6resizeEj

It is my understanding that local references into COMDAT groups are not
allowed.
HPPA is probably particularly sensitive to this because of the "P" PLABEL32
reloc.

Compile command:
/usr/bin/c++   -DHAVE_CONFIG_H -DIHEX_USE_STDBOOL -DUHD_DLL_EXPORTS
-DUHD_IMAGES_DIR=OFF -DUHD_VERSION=30901 -g -O2 -Wformat
-Werror=format-security -D_FORTIFY_SOURCE=2  -fvisibility=hidden
-fvisibility-inlines-hidden -fPIC
-I/home/dave/debian/uhd/uhd-3.9.1/build/include
-I/home/dave/debian/uhd/uhd-3.9.1/host/include
-I/home/dave/debian/uhd/uhd-3.9.1/build/lib/ic_reg_maps
-I/home/dave/debian/uhd/uhd-3.9.1/host/lib/convert
-I/home/dave/debian/uhd/uhd-3.9.1/build/lib/convert
-I/home/dave/debian/uhd/uhd-3.9.1/build/lib/transport/nirio/lvbitx
-I/usr/include/libusb-1.0 -I/home/dave/debian/uhd/uhd-3.9.1/host/lib/usrp
-I/home/dave/debian/uhd/uhd-3.9.1/host/lib/usrp/cores
-I/home/dave/debian/uhd/uhd-3.9.1/host/../firmware/fx2/common
-I/home/dave/debian/uhd/uhd-3.9.1/host/lib/usrp/common
-I/home/dave/debian/uhd/uhd-3.9.1/host/lib/usrp/common/ad9361_driver    -Wall
-Wextra -Wsign-compare -o CMakeFiles/uhd.dir/usrp/usrp1/io_impl.cpp.o -c
/home/dave/debian/uhd/uhd-3.9.1/host/lib/usrp/usrp1/io_impl.cpp

[Bug c++/67834] [5 Regression] Local references inside comdat groups

[danglin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67834

--- Comment #1 from John David Anglin <danglin at gcc dot gnu.org> ---
This issue now breaks gcc build:

`.LC2' referenced in section
`.gnu.linkonce.t._ZN21mem_alloc_descriptionI9mem_us
ageED1Ev' of build/hash-table.o: defined in discarded section
`.gnu.linkonce.r._
ZN10hash_tableIN8hash_mapIPKv14mem_usage_pairI9mem_usageE21simple_hashmap_traits
I19default_hash_traitsIS2_EEE10hash_entryE11xcallocatorE6expandEv.str1.4' of
bui
ld/hash-table.o

This is with trunk revision 228461.  Occurs in stage2.

[Bug c++/67834] [5 Regression] Local references inside comdat groups

[danglin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67834

--- Comment #2 from John David Anglin <danglin at gcc dot gnu.org> ---
Re comment #2, this is with --disable-comdat added to configure command:

../gcc/configure --with-gnu-as --with-gnu-ld --enable-shared --enable-multiarch
--enable-linker-build-id --build=hppa-linux-gnu --host=hppa-linux-gnu
--target=hppa-linux-gnu --prefix=/home/dave/opt/gnu/gcc/gcc-6
--with-local-prefix=/home/dave/opt/gnu --disable-comdat --enable-threads=posix
--enable-__cxa_atexit --build=hppa-linux-gnu --enable-clocale=gnu
--enable-java-gc=boehm
--enable-languages="c,c++,objc,fortran,obj-c++,java,ada,lto"

[Bug c++/67834] [5 Regression] Local references inside comdat groups

[danglin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67834

John David Anglin <danglin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org

--- Comment #3 from John David Anglin <danglin at gcc dot gnu.org> ---
The ELF specification says "To facilitate removing a group without leaving
dangling references and with only minimal processing of the symbol table, the
following rules are followed.

    References to the sections comprising a group from sections outside of the
group must be made through symbol table entries with STB_GLOBAL or STB_WEAK
binding and section index SHN_UNDEF."

The label _ZN3uhd9transport3sphL19handle_overflow_nopEv is not globalized.

Probably, TREE_PUBLIC is not being set or there needs to be an addition
check added to assemble_start_function to globalize COMDAT functions.  Jason,
could you take a look?

[Bug c++/67834] [5 Regression] Local references inside comdat groups

[danglin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67834

--- Comment #4 from John David Anglin <danglin at gcc dot gnu.org> ---
I suppose this is a package bug but it is present in a number
of packages:

static inline void handle_overflow_nop(void){}

class recv_packet_handler{
public:
  ...
private:
    vrt_unpacker_type _vrt_unpacker;
    size_t _header_offset_words32;
    double _tick_rate, _samp_rate;
    bool _queue_error_for_next_call;
    size_t _alignment_faulure_threshold;
    rx_metadata_t _queue_metadata;
    struct xport_chan_props_type{
        xport_chan_props_type(void):
            packet_count(0),
            handle_overflow(&handle_overflow_nop),
            fc_update_window(0)
        {}
        get_buff_type get_buff;
        issue_stream_cmd_type issue_stream_cmd;
        size_t packet_count;
        handle_overflow_type handle_overflow;
        handle_flowctrl_type handle_flowctrl;
        size_t fc_update_window;
    };
    ...
};

Should there be a warning about a potential dangling reference?

[Bug c++/67834] [5 Regression] Local references inside comdat groups

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67834

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |5.3