github.com/afumu/libc@v0.0.6/musl/src/math/i386/atan2.s (about)

     1  .global atan2
     2  .type atan2,@function
     3  atan2:
     4  	fldl 4(%esp)
     5  	fldl 12(%esp)
     6  	fpatan
     7  	fstpl 4(%esp)
     8  	fldl 4(%esp)
     9  	mov 8(%esp),%eax
    10  	add %eax,%eax
    11  	cmp $0x00200000,%eax
    12  	jae 1f
    13  		# subnormal x, return x with underflow
    14  	fsts 4(%esp)
    15  1:	ret