[GHC] #10779: .so files in 64-bit Debian builds are 4% larger than they have to be

[GHC]

#10779: .so files in 64-bit Debian builds are 4% larger than they have to be
-------------------------------------+-------------------------------------
        Reporter:  thomie            |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  low               |               Milestone:
       Component:  Build System      |                 Version:  7.10.2
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by thomie):

 Below, filepath-ubuntu.so is from hvr's ppa build of ghc-7.10.2 (exact
 file mentioned above), filepath-debian.so is from the Debian download.

 {{{
 $ size -A filepath-ubuntu.so filepath-debian.so
 filepath-ubuntu.so  :
 section                size      addr
 .note.gnu.build-id       36       400
 .gnu.hash              2564       440
 .dynsym                8976      3008
 .dynstr               26101     11984
 .gnu.version            748     38086
 .gnu.version_r           32     38840
 .rela.dyn             12816     38872
 .rela.plt                96     51688
 .init                    26     51784
 .plt                     80     51824
 .text                 60569     51904
 .fini                     9    112476
 .rodata                 278    112488
 .eh_frame                 4    112768
 .init_array               8   2210792
 .fini_array               8   2210800
 .jcr                      8   2210808
 .dynamic                624   2210816
 .got                    400   2211440
 .got.plt                 56   2211840
 .data                  6624   2211896
 .bss                      8   2218520
 Total                120071

 filepath-debian.so  :
 section                size      addr
 .note.gnu.build-id       36       400
 .hash                  2556       440
 .gnu.hash              2564      3000
 .dynsym                8976      5568
 .dynstr               26101     14544
 .gnu.version            748     40646
 .gnu.version_r           32     41400
 .rela.dyn             12816     41432
 .rela.plt                72     54248
 .init                    14     54320
 .plt                     64     54336
 .text                 60596     54400
 .fini                     9    114996
 .rodata                 278    115008
 .eh_frame_hdr            20    115288
 .eh_frame                68    115312
 .init_array               8   2215936
 .fini_array               8   2215944
 .jcr                      8   2215952
 .dynamic                640   2215960
 .got                    400   2216600
 .got.plt                 48   2217000
 .data                  6624   2217048
 .bss                      8   2223672
 .comment                 39         0
 Total                122733
 }}}

 filepath-debian.so contains additional `.hash`, `.eh_frame_hdr` and
 `.comment` sections. After removing those, the `size` utility reports a
 similar file size as it does for filepath-ubuntu.so:

 {{{
 $ strip -R .hash -R .eh_frame_hdr -R .comment filepath-debian.so

 $ size filepath-debian.so
    text    data     bss     dec     hex filename
  112394    7736       8  120138   1d54a filepath-debian.so
 }}}

 But the file did not get much smaller. I don't understand why not.
 {{{
 $ wc -c filepath-debian.so
 128456 filepath-debian.so
 }}}

 My system:
 {{{
 $ ld --version   # Binutils also provides `size` and `strip`.
 GNU ld (GNU Binutils for Ubuntu) 2.24

 $ gcc --version
 gcc (Ubuntu 4.8.4-2ubuntu1~14.04) 4.8.4
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10779#comment:2>
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