func BtoF(b uint64) int {
b &= 0xFFFF0000
if b == 0 {
return 0
}
return gc.Bitno(b) - 16 + x86.REG_X0
}
func BtoR(b uint64) int {
b &= 0xffff
if gc.Nacl {
b &^= (1<<(x86.REG_BP-x86.REG_AX) | 1<<(x86.REG_R15-x86.REG_AX))
} else if obj.Framepointer_enabled != 0 {
// BP is part of the calling convention if framepointer_enabled.
b &^= (1 << (x86.REG_BP - x86.REG_AX))
}
if b == 0 {
return 0
}
return gc.Bitno(b) + x86.REG_AX
}