Re: [avr-gcc-list] multiply by constant always expands to int

[Ben Jackson]

On Tue, Dec 06, 2005 at 07:33:51PM +0000, Paulo Marques wrote:
> 
> I thought this would just happen with any multiply operation, and tried 
> to build a simple test case, and to my surprise everything was just fine.

I just did the same thing.  Turns out there are at least two things
required for my version:  one of the operands has to be `const', and
you must use `-Os':

        void
        g(void)
        {
                extern char f(char);
                const char y = 20;
                char x, z;

                z = f(x * y);
        }

Turn off `const' or `-Os' and you get __mulqi3, else __mulhi3

You can probably also just move the literal '20' in for y;

-- 
Ben Jackson
<address@hidden>
http://www.ben.com/