Re: Multiple jumps in one instruction

[Toshi Morita <tm2 at best dot com>]

> 
> This may seem odd, but I am looking to port gcc to a new processor
> architecture. I have spend the last week or so reading the documentation
> but there is still one question left that I can not answer for definate.
> 
> For example if I had a line like
> 
>        a = func1(n)+func2(n);
> 
> I would want to compile this into a single jump instruction that goes
> to two places. Think of it as hardware multi-threading and you should
> get the idea.
> 
> The problem is if gcc makes sufficient assumptions about the way that
> processors work that this is going to be mighty hard to implement then
> I might have to look at a new compiler from scratch. Obviously I want
> to avoid this at all possible costs.
> 
> JAB.
> 
> -- 
> Jonathan A. Buzzard                 Email: jonathan@buzzard.org.uk
> Northumberland, United Kingdom.       Tel: +44(0)1661-832195

This scheme has huge problems.

Consider this:

static int a = 5;

void func1(void)
{
	return a *= 5;
}

void func2(void)
{
	return a *= 3;
}

void main(void)
{
	printf("%d\n", func1() + func2());
}

This program semi-randomly print either 90 or 100 depending
on the timing between threads.

Toshi