------- Comment #3 from rguenth at gcc dot gnu dot org 2010-03-31 11:08 -------
fsin/fcos are known to get wrong results for certain values and their precision
is nowhere near acceptable. Note that when emitting fsin/fcos GCC omits
necessary range reduction for large arguments - fsin/fcos only work
correctly for a limited range.
Proper code is in libm for example:
ENTRY(__sinf)
flds 4(%esp)
fxam
fstsw %ax
movb $0x45, %dh
andb %ah, %dh
cmpb $0x05, %dh
je 3f
4: fsin
fnstsw %ax
testl $0x400,%eax
jnz 1f
ret
.align ALIGNARG(4)
1: fldpi
fadd %st(0)
fxch %st(1)
2: fprem1
fnstsw %ax
testl $0x400,%eax
jnz 2b
fstp %st(1)
fsin
ret
3:
#ifdef PIC
pushl %ebx
cfi_adjust_cfa_offset (4)
cfi_rel_offset (ebx, 0)
LOAD_PIC_REG (bx)
call __errno_locat...@plt
movl $EDOM, (%eax)
popl %ebx
cfi_adjust_cfa_offset (-4)
cfi_restore (ebx)
#else
call __errno_locat...@plt
movl $EDOM, (%eax)
#endif
jmp 4b
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43599
