[Bug ld/12614] New: mingw ld omits needed jump stubs in link involving --start/end-group

[dklprogramming at web dot de]

http://sourceware.org/bugzilla/show_bug.cgi?id=12614

           Summary: mingw ld omits needed jump stubs in link involving
                    --start/end-group
           Product: binutils
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ld
        AssignedTo: address@hidden
        ReportedBy: address@hidden


Created attachment 5337
  --> http://sourceware.org/bugzilla/attachment.cgi?id=5337
Example with makefile

Related to a patch that was applied to ld between binutils 2.17 and 2.18:
    "Eliminate redundant jump stubs on windows/cygwin/MinGW"
    <http://sourceware.org/ml/binutils/2007-01/msg00162.html>

See also:
<http://sourceware.org/cgi-bin/cvsweb.cgi/src/ld/pe-dll.c?cvsroot=src#rev1.95>
<http://sourceware.org/git/?p=binutils.git;a=commit;h=6fd5362b96f51a2763e1a55e6cc78e604f369957>


It appears that ld accidentally excludes jump stubs from an import library,
when linking like this:
    main.o -( libfoo.dll.a test.o -)
where main.o references a symbol from the import library, and test.o uses
a second symbol from the import library. In that case the jump stub for the
second symbol (referenced only by test.o) is not included into the executable.

If only test.o but not main.o reference a symbol in the import library, the
problem does not occur. (Using __declspec(dllimport) on the symbol referenced
in test.o prevents running into this issue completely.)

Here is an example; it requires a toolchain targetting mingw32:

    $ cat main.c
    void test();
    void bar();
    void mainCRTStartup() {
        test();
        bar();
    }
    $ cat test.c
    void foo();
    void test() {
        foo();
    }
    $ cat foo.def
    LIBRARY foo.dll
    EXPORTS
    foo
    bar
    $ i586-mingw32msvc-gcc -Wall -c main.c -o main.o
    $ i586-mingw32msvc-gcc -Wall -c test.c -o test.o
    $ i586-mingw32msvc-dlltool --input-def foo.def --output-lib libfoo.dll.a
    $ i586-mingw32msvc-ld -o good.exe main.o test.o libfoo.dll.a
    $ i586-mingw32msvc-ld -o bad.exe main.o "-(" libfoo.dll.a test.o "-)"
    $ i586-mingw32msvc-objdump -D good.exe > good-disasm.txt
    $ i586-mingw32msvc-objdump -D bad.exe > bad-disasm.txt

Excerpt from good-disasm.txt:

    00401000 <_mainCRTStartup>:
      401000:    55                       push   %ebp
      401001:    89 e5                    mov    %esp,%ebp
      401003:    83 ec 08                 sub    $0x8,%esp
      401006:    e8 09 00 00 00           call   401014 <_test>
      40100b:    e8 14 00 00 00           call   401024 <_bar>
      401010:    c9                       leave  
      401011:    c3                       ret    
      401012:    90                       nop
      401013:    90                       nop

    00401014 <_test>:
      401014:    55                       push   %ebp
      401015:    89 e5                    mov    %esp,%ebp
      401017:    83 ec 08                 sub    $0x8,%esp
      40101a:    e8 0d 00 00 00           call   40102c <_foo>
      40101f:    c9                       leave  
      401020:    c3                       ret    
      401021:    90                       nop
      401022:    90                       nop
      401023:    90                       nop

    00401024 <_bar>:
      401024:    ff 25 34 20 40 00        jmp    *0x402034
      40102a:    90                       nop
      40102b:    90                       nop

    0040102c <_foo>:
      40102c:    ff 25 38 20 40 00        jmp    *0x402038
      401032:    90                       nop
      401033:    90                       nop

Excerpt from bad-disasm.txt:

    00401000 <_mainCRTStartup>:
      401000:    55                       push   %ebp
      401001:    89 e5                    mov    %esp,%ebp
      401003:    83 ec 08                 sub    $0x8,%esp
      401006:    e8 11 00 00 00           call   40101c <_test>
      40100b:    e8 04 00 00 00           call   401014 <_bar>
      401010:    c9                       leave  
      401011:    c3                       ret    
      401012:    90                       nop
      401013:    90                       nop

    00401014 <_bar>:
      401014:    ff 25 34 20 40 00        jmp    *0x402034
      40101a:    90                       nop
      40101b:    90                       nop

    0040101c <_test>:
      40101c:    55                       push   %ebp
      40101d:    89 e5                    mov    %esp,%ebp
      40101f:    83 ec 08                 sub    $0x8,%esp
      401022:    e8 d9 ef bf ff           call   0 <_foo>
      401027:    c9                       leave  
      401028:    c3                       ret    
      401029:    90                       nop
      40102a:    90                       nop
      40102b:    90                       nop

Notice that in bad.exe the <_foo> stub is not present, and there is a 'call 0'
in <_test>.

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