I have had a bug report from people who tested my gfortran binaries for
mingw-w64 that the float variants of math functions aren't working properly.
The proper report that was sent to me has this example:
C:\gfortran\test\single_bug>type table.f90
program table
real x
integer i
write(*,*) ' x sin(x) cos(x) tan(x)'
do i = 0, 10
x = i
write(*,*) x, sin(x), cos(x), tan(x)
end do
end program table
C:\gfortran\test\single_bug>c:\gfortran\win64\bin\x86_64-pc-mingw32-gfortran
table.f90 -o table
C:\gfortran\test\single_bug>table
x sin(x) cos(x) tan(x)
0.000000 0.000000 0.000000 0.000000
1.000000 1.000000 1.000000 1.000000
2.000000 2.0000 2.0000 2.0000
3.000000 3.0000 3.0000 3.0000
4.000000 4.0000 4.0000 4.0000
5.000000 5.0000 5.0000 5.0000
6.000000 6.0000 6.0000 6.0000
7.000000 7.0000 7.0000 7.0000
8.000000 8.0000 8.0000 8.0000
9.000000 9.0000 9.0000 9.0000
10.00000 10.0000 10.0000 10.0000
Indeed, there is a difference between a C function that calls sinf():
#include <math.h>
float foo(float *x) { return sinf(*x); }
which is compiled into:
_foo:
LFB47:
pushq %rbp
LCFI0:
movq %rsp, %rbp
LCFI1:
subq $32, %rsp
LCFI2:
movq %rcx, 16(%rbp)
movq 16(%rbp), %rax
movss (%rax), %xmm0
call _sinf
leave
ret
and the equivalent Fortran function:
real function foo(x)
real x
foo = sin(x)
end function foo
that is compiled into:
_foo_:
LFB2:
pushq %rbp
LCFI0:
movq %rsp, %rbp
LCFI1:
subq $64, %rsp
LCFI2:
movq %rcx, 16(%rbp)
movq 16(%rbp), %rax
movss (%rax), %xmm0
call _sinf
movss %xmm0, -4(%rbp)
movl -4(%rbp), %eax
movl %eax, -20(%rbp)
movss -20(%rbp), %xmm0
leave
ret
(Notice the extra lines between the call to _sinf and the leave.)
--
Summary: Wrong code for single precision math functions on
x86_64-pc-mingw32
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: fxcoudert at gcc dot gnu dot org
GCC build triplet: i386-pc-mingw32
GCC host triplet: i386-pc-mingw32
GCC target triplet: x86_64-pc-mingw32
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33561
