Re: [PATCH, PR 67133] Always change gimple fntype in cgraph_edge::redirect_call_stmt_to_callee

[Jan Hubicka <hubicka@ucw.cz>]

> Hi,
> 
> even though PR 67133 has been avoided by a different patch, I believe
> the patch below is the correct fix.  It modifies the function that
> changes call statements according to call graph edges so that it
> changes the fntype of the call statements also when
> combined_args_to_skip is NULL.  This code path is taken for example
> when a call is redirected to __builtin_unreachable and then the type
> of the callee function is likely to mismatch with fntype of the
> statement, which can confuse the compiler later on.
> 
> If we agree it is a good idea, I'd like to also propose a patch
> making the gimple verifier check whether fntypes of direct call
> statements match the types of the callee (or at least that they have
> the same number of same-typed arguments).
> 
> The patch has been bootstrapped and tested on x86_64-linux, the
> testcase is already checked in.  OK for trunk?
> 
> Thanks,
> 
> Martin
> 
> 
> 2015-08-17  Martin Jambor  <mjambor@suse.cz>
> 
> 	PR middle-end/67133
> 	* cgraph.c (redirect_call_stmt_to_callee): Set gimple call fntype also
> 	when redirecting without removing any parameters.

This makes sense in the case of __builtin_unreachable.  I wonder if we have
some problems in cases where LTO or indirect call code places in incompatible
declaration.

Patch is fine with me, but I would like Richi to have final word on this one.

Honza
> 
> diff --git a/gcc/cgraph.c b/gcc/cgraph.c
> index 22a9852..5e5b308 100644
> --- a/gcc/cgraph.c
> +++ b/gcc/cgraph.c
> @@ -1461,6 +1461,7 @@ cgraph_edge::redirect_call_stmt_to_callee (void)
>      {
>        new_stmt = e->call_stmt;
>        gimple_call_set_fndecl (new_stmt, e->callee->decl);
> +      gimple_call_set_fntype (new_stmt, TREE_TYPE (e->callee->decl));
>        update_stmt_fn (DECL_STRUCT_FUNCTION (e->caller->decl), new_stmt);
>      }
>