long conversion of short expression.

[Paul Guthrie]

Here is a case where 68000 compilers don't seem to agree. 
In the following code segment, the two shorts multiplied together
exceed the size of a short, but the question is, is the result
of the multiplication really a short to be converted to a
long, or a long already?

        main()
        {

                short x=0x18,y=0x588;
                long z=0x100000;
                printf("%lx\n",z+(x*y));
        }
 
Should the compiler generate
	move -2(fp),d0
	muls -4(fp),d0
	extl d0
	addl -8(fp),d0
or should the extl instruction be left out?  muls has already
generated a long result.  Both the Sun and GNU compilers
do not use the extl, but I have seen other compilers that
would.

-- 
Paul Guthrie
chinet!nsacray!paul