[Complexity] Optimize get_min_scalefactor()
# Basic info
This is a subtask of #1009 - it splits off the complexity optimization of the function L_norm_arr(). This optimization is BE.
# Bug description
Avoid `IF()`-operators. The `IF()` operator has a complexity count of 3; instead, `if()` can be used if it conditions only one basic operator (control operators excluded).
```
Word16 get_min_scalefactor( Word32 x, Word32 y )
{
#ifndef PATCH
Word16 scf = Q31;
move16();
test();
IF( x == 0 && y == 0 )
{
return 0;
}
IF( x != 0 )
{
scf = s_min( scf, norm_l( x ) );
}
IF( y != 0 )
{
scf = s_min( scf, norm_l( y ) );
}
return scf;
#else
Word16 scf_y;
Word16 scf = Q31;
move16();
test();
if ( x == 0 && y == 0 )
{
scf = 0;
move16();
}
if ( x != 0 )
{
scf = norm_l( x );
}
scf_y = norm_l( y );
if ( y != 0 )
{
scf = s_min( scf_y, scf );
}
return scf;
#endif
}
```
The propsed patch saves 7-8 cycles per function call.
# Ways to reproduce
See #1009 for commandline.
issue