github.com/afumu/libc@v0.0.6/musl/src/math/i386/acosl.s (about)

     1  .global acosl
     2  .type acosl,@function
     3  acosl:
     4  	fldt 4(%esp)
     5  	fld %st(0)
     6  	fld1
     7  	fsub %st(0),%st(1)
     8  	fadd %st(2)
     9  	fmulp
    10  	fsqrt
    11  	fabs         # fix sign of zero (matters in downward rounding mode)
    12  	fxch %st(1)
    13  	fpatan
    14  	ret