[Bug optimization/11960] New: "can't find a register in class..." when using glibc 2.2.5 fmod() with -O2

[alexander at malmberg dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11960

           Summary: "can't find a register in class..." when using glibc
                    2.2.5 fmod() with -O2
           Product: gcc
           Version: 3.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: alexander at malmberg dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu

Using fmod() from glibc 2.2.5 with function calls as arguments gives the
following error when compiling with -O2:

test11_i.c:6: error: can't find a register in class `FP_TOP_REG' while reloading
`asm'

With -O0, it compiles ok. This is on objc-improvements-branch, but it doesn't
seem to be a branch-specific issue.

Preprocessed (and cleaned) source:

extern double fmod (double __x, double __y);

extern __inline double fmod (double __x, double __y)
{
  register long double __value;
  __asm __volatile__
  ("1:  fprem\n\t" "fnstsw      %%ax\n\t" "sahf\n\t" "jp        1b"
    : "=t" (__value)
    : "0" (__x), "u" (__y)
    : "ax", "cc");
  return __value; }

double quux(void);

int main(int argc,char **argv)
{
    double d=fmod(quux(),quux());

    return 0;
}

double quux(void)
{
    return 1.2;
}