On Wed, Nov 19, 2008 at 09:32:10AM +0100, Daniel Veillard <[EMAIL PROTECTED]>
wrote:
> On Sat, Nov 15, 2008 at 06:24:48PM +0100, Mike Hommey wrote:
> > Hi,
> >
> > Have you considered using -Bsymbolic linker option instead of the
> > elfgcchack.h hack ?
>
> Hum, no ... I don't know -Bsymbolic, but I fail to see how the
> linker could solve the problem I tried to solve (bypass costly ELF
> lookup when doing internal library calls). Could you explain ?
My understanding of what elfgcchack.h tries to achieve is to remove
indirect calls (through the PLT) for function calls within the library.
-Bsymbolic just does that:
$ cat test.c
int foo(int a)
{
return a;
}
int bar(void)
{
return foo(0);
}
$ gcc -shared -fPIC -o test.so test.c
$ objdump -d test.so |less
$ objdump -d test.so| grep foo
000003c8 <[EMAIL PROTECTED]>:
000004bc <foo>:
4dd: e8 e6 fe ff ff call 3c8 <[EMAIL PROTECTED]>
$ gcc -Wl,-Bsymbolic -shared -fPIC -o test.so test.c
$ objdump -d test.so| grep foo
0000049c <foo>:
4bd: e8 da ff ff ff call 49c <foo>
-Bsymbolic is supposed to do that for most symbols. -Bsymbolic-functions
is specialized to function calls.
Mike
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