There are

[hjl@gnu-20 hjl]$ readelf -s /usr/lib/libm.a | grep " coshf"
     5: 00000000   145 FUNC    WEAK   DEFAULT    1 coshf

on ia32 and x86_64, but

[hjl@gnu-2 kernel]$ readelf -s /usr/lib/libm.a | grep " coshf"
    13: 0000000000000000  1616 FUNC    GLOBAL DEFAULT    1 coshf

on ia64. As the result, people can't override math functions in libm.a on
ia64 since other internal math functions in libm.a, like __ieee754_coshf,
are needed by glibc, which leads to symbol multiple definition error.