[Bug c/54303] New: -fdata-sections -ffunction-sections and -fmerge-constants do not work well together

["tom.rini at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54303

             Bug #: 54303
           Summary: -fdata-sections -ffunction-sections and
                    -fmerge-constants do not work well together
    Classification: Unclassified
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: tom.rini@gmail.com


Created attachment 28045
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28045
Testcase for the issue

The attached test-case demonstrates the problem I see:
$ arm-linux-gnueabi-gcc -Wall -fdata-sections -ffunction-sections -o
non-collected-strings.o -c non-collected-strings.c
$ arm-linux-gnueabi-gcc -Wl,--gc-sections -o non-collected-strings
non-collected-strings.o
$ strings non-collected-strings | grep here
This string should not be here
This string should be here
$ arm-linux-gnueabi-nm non-collected-strings| grep me
00000000004004d0 t frame_dummy
00000000004004f2 T keep_me
$ arm-linux-gnueabi-nm non-collected-strings.o | grep me
0000000000000000 T garbage_collect_me
0000000000000000 T keep_me
$ arm-linux-gnueabi-objdump -h non-collected-strings.o | grep str
non-collected-strings.o:     file format elf32-littlearm
  3 .rodata.str1.4 0000003c  00000000  00000000  00000034  2**2

And all strings in the object file are coalesced into a single section.

Note that on x86-64 this works as expected as the last step shows instead:
$ objdump -h non-collected-strings.o  | grep str
non-collected-strings.o:     file format elf64-x86-64
  3 .rodata.str1.8 0000001f  0000000000000000  0000000000000000  00000040  2**3
  5 .rodata.str1.1 0000001b  0000000000000000  0000000000000000  0000006f  2**0

I've verified this with a few different arm-linux-gnueabi toolchains (ELDK 4.2,
ELDK 5.2.1, Linaro (4:4.6.2-7 in Ubuntu) and this seems like a long-standing
thing, not Linaro-patch specific.