[PATCH]: Integrate gfortran with MPC

[Tobias Burnus]

Summary: Try the C program with and without -fcx-fortran-rules; for
details, see below.

Tobias


Steve Kargl wrote:
> There appears to be a middle-end issue here as well.  Consider,
> the following program:
>   
[...]
> troutmask:sgk[205] ./z
>      NaN     NaN     NaN     NaN
>      NaN     NaN     NaN     NaN
>   
I tried a couple of other Fortran compilers - and the result is:

Intel Fortran Compiler 11.1:
NaN NaN NaN NaN
NaN NaN (NaN,NaN)
InfinityInfinity NaN NaN

g95, openf95:
NaN NaN NaN NaN
NaN NaN (NaN,NaN)
NaN NaN NaN NaN

Sunf95:
InfinityInfinityInfinityInfinity
Inf Inf (Inf,Inf)
InfinityInfinityInfinityInfinity

NAG f95 (with IEEE_SET_HALTING_MODE set to .false. and with compile-time
foldings removed):
NaN NaN
NaN NaN (NaN,NaN)
InfinityInfinity


* * *

However, more interesting is the following C program. The equivalent
Fortran program produces NaN (with gfortran) but in C one gets with GCC:
inf + inf i
inf + inf i
inf + inf i
and with Intel's icc (9.1):
nan + nan i
nan + nan i
nan + nan i

And here is something interesting: "gcc -fcx-fortran-rules" (!!!!!) gives:

inf + inf i
nan + nan i
nan + nan i

which hints at the problem.


Here is the C code:

#include <stdio.h>
#include <complex.h>

int main()
{
complex double z1, z2, z3;
z1 = 0.0;
z2 = 1.0 + 2.0*I;
z3 = (1.0 + 2.0*I)/0.0;
printf("%f + %f i\n", __real__ (z3), __imag__ (z3));
printf("%f + %f i\n", __real__ (z2/z1), __imag__ (z2/z1));
z3 = z2/z1;
printf("%f + %f i\n", __real__ (z3), __imag__ (z3));
}


And here the Fortran code:

Program test
complex(kind=8) z1, z2, z3;
z1 = 0.0
z2 = cmplx(1.0d0,2.0d0)
z3 = cmplx(1.0d0 + 2.0d0)/0.0d0;
print *, real(z3,kind=8),aimag(z3)
print *, real(z2/z1,kind=8),aimag(z2)
z3 = z2/z1;
print *, real(z3,kind=8),aimag(z3)
end program test