Andrew Haley wrote:
Chris Jefferson writes:
> One thing which comes up regularly in various C and C++
> messageboards is that statements like "f() + g()" and "a(f(), g())"
> do not declare which order f() and g() will be executed in.
>
> How hard would it be to fix the order of execution in gcc/g++?
> Could someone point me to the piece of code which must change, or
> if it is only a very small change, the actual change required? I
> would very much like to be able to benchmark this, as I can find no
> previous case where someone has tried fixing the order of execution
> to see if it actually makes any measureable difference.
The easiest way is during gimplification: you'd walk over the arglist
from left to right, calling
gimplify_expr (&arg, pre_p, post_p,
is_gimple_formal_tmp_var, fb_rvalue);
on each arg.
But would it be sufficient?
I guess you would also have to make sure that further passes (i.e.
out-of-ssa) do not revert what you have just done.
> Would anyone be interested in this being added as a command line argument?
That would be a Bad Thing.
Good that a bad thing is hard to implement, that's morality.
Cheers,
Roberto
