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On 05/23/11 09:21, Nick Clifton wrote:
> Hi Alex, Hi Jeff, Hi Richard,
>
> Consider the following small test case:
>
> % cat test1.c
> extern int g (void) __attribute__ ((visibility("protected")));
> int f (void) { return g (); }
>
> % cat test2.c
> extern int g(void) __attribute__ ((visibility("protected")));
> int i;
> int g (void) { return i; }
>
> % gcc -fPIC -c test1.c test2.c
> % gcc -shared -o libtest_protected.so test1.o test2.o
>
> When compiled with a MN10300 toolchain based on the current FSF GCC
> and binutils sources the final link will fail with:
>
> test1.o: In function `f':
> test1.c:(.text+0x7): warning: error: inappropriate relocation type for
> shared library (did you forget -fpic?)
>
> The problem here is that GCC has decided that since "g" is protected
> it does not need a PLT entry. But the linker has decided that since
> "g" is a function it does need a PLT entry (even though it is
> protected) so that function pointer comparison will work. (See the
> definition of SYMBOL_REFERENCES_LOCAL in bfd/elf-bfd.h for more
> information on this).
>
> I have a small patch that fixes this problem (see below), but I am not
> sure if this is the correct solution. As far as I can see, this is
> not an MN10300 specific problem however, so surely other targets ought
> to have similar problems ? (But other targets do not seem to use
> targetm.binds_local_p to decide if a symbol is global or local. cf/
> mn10300_encode_section_info).
>
> Anyway any advice or comments on the situation would be appreciated.
This isn't something I have much experience with; presumably we must
have the PLT entry even though "g" is considered protected? If so, then
ISTM GCC will need to cope/adapt and your approach seems as good as any
other to me -- unless we wanted to move the code into a more generic
location.
jeff
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