I have this function:

function Compare(v1, v2: Integer): Integer;

And called like this:

Result := Compare(stack.Pop, stack.Pop);

The behavior is that the second Pop is evaluated first, thus reversed the meaning of the function.

Is it true that all parameter evaluation goes from right to left?

Thanks!
Xiangrong

Xiangrong Fang wrote

Is it true that all parameter evaluation goes from right to left?

The order in which parameters are evaluated is unrelated to the calling convention. This order has always been undefined in FPC, and it is also undefined in recent versions of Delphi.

Jonas

Nope, calling convention only specifies parameter passing order, not parameter evaluation order. If you want to specify exactly how the parameters are evaluated, put each in a local variable first, according to your order needs.

Jonas Maebe wrote

The order in which parameters are evaluated is unrelated to the calling convention. This order has always been undefined in FPC, and it is also undefined in recent versions of Delphi.

I am wondering what the advantage is to *not* garantee a left to right order. I can't think of a situation where changing this order makes any sense.

In our previous episode, J?rgen Hestermann said:

I am wondering what the advantage is to *not* garantee a left to right order.

Undefined order allows to do the evaluation that needs the most temps first I guess, which reduces spilling.

Jürgen Hestermann wrote

I am wondering what the advantage is to *not* garantee a left to right order.

http://svn.freepascal.org/cgi-bin/viewvc.cgi/trunk/compiler/ncal.pas?view=markup#l3268

Jonas

Jonas Maebe wrote

On 07 Dec 2013, at 18:50, Jürgen Hestermann wrote: > I am wondering what the advantage is to *not* garantee a left to right order. http://svn.freepascal.org/cgi-bin/viewvc.cgi/trunk/compiler/ncal.pas?view=markup#l3268

Thanks Jonas.
Interesting what complex things happen behind the scene...