Some really strange GIMPLE

[David Malcolm]

On Tue, 2021-04-27 at 20:10 +0000, Gary Oblock via Gcc wrote:
> I'm chasing a bug and I used Creduce to produce a
> reduced test case. However, that's really beside to
> point.
> 
> I this file:
> --------------------------------
> typedef struct basket {
> } a;
> long b;
> a *basket;
> int d, c, e;
> a *flake[2];
> void primal_bea_mpp();
> void primal_net_simplex() {
>   flake[1] = &basket[1];
>   primal_bea_mpp(d, d, d, b, flake, 0, e, c, c, d);
> }
> --------------------------------
> Produces this GIMPLE:
> ---------------------------------
> ;; Function primal_net_simplex (primal_net_simplex, funcdef_no=3,
> decl_uid=4447, cgraph_uid=16, symbol_order=41) (executed once)
> 
> primal_net_simplex ()
> {
>   <bb 2> [local count: 1073741824]:
>   _1 = basket;
>   static struct a * flake[2];
> struct a *[2]
>   flake[1] = _1;
>   _2 = d;
>   _3 = c;
>   _4 = e;
>   _5 = b;
>   primal_bea_mpp (_2, _2, _2, _5, &flake, 0, _4, _3, _3, _2);
>   return;
> 
> }
> --------------------------------------
> These standard calls were used to dump this:
> 
>   FOR_EACH_FUNCTION_WITH_GIMPLE_BODY ( node)
>   {
>     struct function *func = DECL_STRUCT_FUNCTION ( node->decl);
>     dump_function_header ( file, func->decl, (dump_flags_t)0);
>     dump_function_to_file ( func->decl, file, (dump_flags_t)0);
>   }
> 
> The GIMPLE above looks malformed to me. Is that the case
> or am I not grasping what's going on here?

What about it looks malformed to you?

The declaration of primal_bea_mpp and primal_net_simplex could probably
use some parameters, rather than being empty, which might make things
look more sane [1].  I think -Wstrict-prototypes will catch this.

Dave

[1] https://wiki.sei.cmu.edu/confluence/display/c/DCL20-C.+Explicitly+specify+void+when+a+function+accepts+no+arguments