Re: [Tinycc-devel] [PATCH] tcc: remove buggy nodata_wanted optimization

[Michael Matz]

Hi,

On Thu, 22 Feb 2018, grischka wrote:

> However NODATA_WANTED does more than that, for example it also suppresses
> the "hello" with
>         if (0) puts("hello");
>
> Therefor I'd suggest a less radical change, such as:
>
> @@ -6916,7 +6916,7 @@ static void decl_initializer_alloc(CType *type, 
> AttributeDef *ad, int r,
>         align = 1;
>     }
>
> -    if (NODATA_WANTED)
> +    if (!v && NODATA_WANTED)
>         size = 0, align = 1;
>
>     if ((r & VT_VALMASK) == VT_LOCAL) {
>
>
> Thus variable space will be allocated always but initializers are
> still suppressed.  (Bypassing initializers with goto is not allowed).

For statics it is.  E.g. the following program is valid and must print 
42:

#include <stdio.h>
int main() {
  goto doit;
  if (0) {
    static int a = 42;
doit:
    printf ("%d\n", a);
  }
}

But the idea of supressing only nameless entities is a good one I think.


Ciao,
Michael.