On Sun, Aug 29, 2021 at 10:07 AM Tobias Burnus <tob...@codesourcery.com> wrote:
>
> Hi all, hi Richard,
>
> On 27.08.21 21:48, Richard Biener wrote:
> >> It looks really nice with "-O1 -fno-inline" :-)
> >> The callee 'rank_p()' is mostly optimized and in the
> >> caller only those struct elements are set, which are used:
> >>
> >> integer(kind=4) rank_p (struct CFI_cdesc_t & _this)
> >> {
> >> _1 = _this_11(D)->base_addr;
> >> _2 = _this_11(D)->rank;
> >> ...
> >> rnk_13 = (integer(kind=4)) _2;
> >> return rnk_13;
> >> }
> >>
> >> void selr_p ()
> >> {
> >> ...
> >> struct CFI_cdesc_t01 cfi.7;
> >> ...
> >> <bb 2> [local count: 537730764]:
> >> cfi.7.rank = 1;
> >> cfi.7.base_addr = 0B;
> > You need to do the accesses above using the generic 't' type as well,
> > otherwise they are non-conflicting TBAA wise.
>
> First, I wonder why the following works with C:
>
> struct gen_t { int n; int dim[]; }
>
> int f (struct gen_t *x) {
> if (x->n > 1) x->dim[0] = 5;
> return x->n;
> }
>
> void test() {
> struct { int n; int dim[2]; } y;
> y.n = 2;
> f ((struct gen_t*) &y);
> }
>
> Or doesn't it?
It probably doesn't and suffers from the same issue as your
original fortran code.
>In any case, that's how it is suggested
> and 'y.n' is not accessed using 'gen_t' – there is only
> a cast in the function call. (Which is not sufficient
> in the Fortran FE-code generated code – as tried)
>
> * * *
>
> Otherwise, I can confirm that the following works.
> Does this original dump now looks fine?
>
> struct CFI_cdesc_t01 cfi.2;
> ...
> ((struct CFI_cdesc_t *) &cfi.2)->version = 1;
> ((struct CFI_cdesc_t *) &cfi.2)->rank = 1;
> ((struct CFI_cdesc_t *) &cfi.2)->type = 1025;
> ((struct CFI_cdesc_t *) &cfi.2)->attribute = 0;
> ((struct CFI_cdesc_t *) &cfi.2)->base_addr = intp.data;
> ((struct CFI_cdesc_t *) &cfi.2)->elem_len = 4;
> ...
> irnk = rank_p ((struct CFI_cdesc_t *) &cfi.2);
Yes, that looks OK now. The idea is you can use the complete
types for storage allocation but you _always_ have to use the
incomplete (with flexarray member) type for all accesses.
Richard.
> Thanks,
>
> Tobias
>
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