c++: Fix ICEs with OBJ_TYPE_REF pretty printing [PR101597]

  Hi!

The following testcase ICEs, because middle-end uses the C++ FE pretty
printing code through langhooks in the diagnostics.
The FE expects OBJ_TYPE_REF_OBJECT's type to be useful (pointer to the
class type it is called on), but in the middle-end conversions between
pointer types are useless, so the actual type can be some random
unrelated pointer type (in the testcase void * pointer).  The pretty
printing code then ICEs on it.

The following patch fixes that by sticking the original
OBJ_TYPE_REF_OBJECT's also as type of OBJ_TYPE_REF_TOKEN operand.
That one must be an INTEGER_CST, all the current uses of
OBJ_TYPE_REF_TOKEN just use tree_to_uhwi or tree_to_shwi on it,
and because it is constant, there is no risk of the middle-end propagating
into it some other pointer type.  So, approach similar to how MEM_REF
treats its second operand or a couple of internal functions (e.g.
IFN_VA_ARG) some of its parameters.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2021-12-30  Jakub Jelinek  <jakub@redhat.com>

	PR c++/101597
gcc/cp/
	* class.c (build_vfn_ref): Build OBJ_TYPE_REF with INTEGER_CST
	OBJ_TYPE_REF_TOKEN with type equal to OBJ_TYPE_REF_OBJECT type.
	* error.c (resolve_virtual_fun_from_obj_type_ref): Use type of
	OBJ_TYPE_REF_TOKEN rather than type of OBJ_TYPE_REF_OBJECT as
	obj_type.
gcc/objc/
	* objc-act.c (objc_rewrite_function_call): Build OBJ_TYPE_REF
	with INTEGER_CST OBJ_TYPE_REF_TOKEN with type equal to
	OBJ_TYPE_REF_OBJECT type.
	* objc-next-runtime-abi-01.c (build_objc_method_call): Likewise.
	* objc-gnu-runtime-abi-01.c (build_objc_method_call): Likewise.
	* objc-next-runtime-abi-02.c (build_v2_objc_method_fixup_call,
	build_v2_build_objc_method_call): Likewise.
gcc/testsuite/
	* g++.dg/opt/pr101597.C: New test.


	Jakub
  

On 12/31/21 04:13, Jakub Jelinek wrote:
> Hi!
> 
> The following testcase ICEs, because middle-end uses the C++ FE pretty
> printing code through langhooks in the diagnostics.
> The FE expects OBJ_TYPE_REF_OBJECT's type to be useful (pointer to the
> class type it is called on), but in the middle-end conversions between
> pointer types are useless, so the actual type can be some random
> unrelated pointer type (in the testcase void * pointer).  The pretty
> printing code then ICEs on it.
> 
> The following patch fixes that by sticking the original
> OBJ_TYPE_REF_OBJECT's also as type of OBJ_TYPE_REF_TOKEN operand.
> That one must be an INTEGER_CST, all the current uses of
> OBJ_TYPE_REF_TOKEN just use tree_to_uhwi or tree_to_shwi on it,
> and because it is constant, there is no risk of the middle-end propagating
> into it some other pointer type.  So, approach similar to how MEM_REF
> treats its second operand or a couple of internal functions (e.g.
> IFN_VA_ARG) some of its parameters.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

This new expectation needs to be documented in tree.def.  OK with that 
change.

> 2021-12-30  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR c++/101597
> gcc/cp/
> 	* class.c (build_vfn_ref): Build OBJ_TYPE_REF with INTEGER_CST
> 	OBJ_TYPE_REF_TOKEN with type equal to OBJ_TYPE_REF_OBJECT type.
> 	* error.c (resolve_virtual_fun_from_obj_type_ref): Use type of
> 	OBJ_TYPE_REF_TOKEN rather than type of OBJ_TYPE_REF_OBJECT as
> 	obj_type.
> gcc/objc/
> 	* objc-act.c (objc_rewrite_function_call): Build OBJ_TYPE_REF
> 	with INTEGER_CST OBJ_TYPE_REF_TOKEN with type equal to
> 	OBJ_TYPE_REF_OBJECT type.
> 	* objc-next-runtime-abi-01.c (build_objc_method_call): Likewise.
> 	* objc-gnu-runtime-abi-01.c (build_objc_method_call): Likewise.
> 	* objc-next-runtime-abi-02.c (build_v2_objc_method_fixup_call,
> 	build_v2_build_objc_method_call): Likewise.
> gcc/testsuite/
> 	* g++.dg/opt/pr101597.C: New test.
> 
> --- gcc/cp/class.c.jj	2021-12-30 15:12:42.706157630 +0100
> +++ gcc/cp/class.c	2021-12-30 17:16:23.567589120 +0100
> @@ -778,7 +778,8 @@ build_vfn_ref (tree instance_ptr, tree i
>   		   cp_build_addr_expr (aref, tf_warning_or_error));
>   
>     /* Remember this as a method reference, for later devirtualization.  */
> -  aref = build3 (OBJ_TYPE_REF, TREE_TYPE (aref), aref, instance_ptr, idx);
> +  aref = build3 (OBJ_TYPE_REF, TREE_TYPE (aref), aref, instance_ptr,
> +		 fold_convert (TREE_TYPE (instance_ptr), idx));
>   
>     return aref;
>   }
> --- gcc/cp/error.c.jj	2021-12-30 15:12:42.714157519 +0100
> +++ gcc/cp/error.c	2021-12-30 17:16:23.568589106 +0100
> @@ -2149,7 +2149,7 @@ dump_expr_init_vec (cxx_pretty_printer *
>   static tree
>   resolve_virtual_fun_from_obj_type_ref (tree ref)
>   {
> -  tree obj_type = TREE_TYPE (OBJ_TYPE_REF_OBJECT (ref));
> +  tree obj_type = TREE_TYPE (OBJ_TYPE_REF_TOKEN (ref));
>     HOST_WIDE_INT index = tree_to_uhwi (OBJ_TYPE_REF_TOKEN (ref));
>     tree fun = BINFO_VIRTUALS (TYPE_BINFO (TREE_TYPE (obj_type)));
>     while (index)
> --- gcc/objc/objc-act.c.jj	2021-12-30 15:12:43.159151319 +0100
> +++ gcc/objc/objc-act.c	2021-12-30 17:16:23.569589092 +0100
> @@ -9644,11 +9644,9 @@ objc_rewrite_function_call (tree functio
>         && TREE_CODE (TREE_OPERAND (function, 0)) == ADDR_EXPR
>         && TREE_CODE (TREE_OPERAND (TREE_OPERAND (function, 0), 0))
>   	 == FUNCTION_DECL)
> -    {
> -      function = build3 (OBJ_TYPE_REF, TREE_TYPE (function),
> -			 TREE_OPERAND (function, 0),
> -			 first_param, size_zero_node);
> -    }
> +    function = build3 (OBJ_TYPE_REF, TREE_TYPE (function),
> +		       TREE_OPERAND (function, 0), first_param,
> +		       build_int_cst (TREE_TYPE (first_param), 0));
>   
>     return function;
>   }
> --- gcc/objc/objc-next-runtime-abi-01.c.jj	2021-12-30 15:12:43.159151319 +0100
> +++ gcc/objc/objc-next-runtime-abi-01.c	2021-12-30 17:16:23.569589092 +0100
> @@ -883,7 +883,7 @@ build_objc_method_call (location_t loc,
>   
>     /* Build an obj_type_ref, with the correct cast for the method call.  */
>     t = build3 (OBJ_TYPE_REF, sender_cast, method,
> -			    lookup_object, size_zero_node);
> +	      lookup_object, build_int_cst (TREE_TYPE (lookup_object), 0));
>     t = build_function_call_vec (loc, vNULL, t, parms, NULL);
>     vec_free (parms);
>     return t;
> --- gcc/objc/objc-gnu-runtime-abi-01.c.jj	2021-12-30 14:16:42.837908238 +0100
> +++ gcc/objc/objc-gnu-runtime-abi-01.c	2021-12-30 17:16:23.569589092 +0100
> @@ -725,7 +725,8 @@ build_objc_method_call (location_t loc,
>         parms->quick_push (TREE_VALUE (method_params));
>   
>     /* Build an obj_type_ref, with the correct cast for the method call.  */
> -  t = build3 (OBJ_TYPE_REF, sender_cast, method, lookup_object, size_zero_node);
> +  t = build3 (OBJ_TYPE_REF, sender_cast, method, lookup_object,
> +	      build_int_cst (TREE_TYPE (lookup_object), 0));
>     t = build_function_call_vec (loc, vNULL, t, parms, NULL);
>     vec_free (parms);
>     return t;
> --- gcc/objc/objc-next-runtime-abi-02.c.jj	2021-12-30 15:12:43.159151319 +0100
> +++ gcc/objc/objc-next-runtime-abi-02.c	2021-12-30 17:16:23.570589078 +0100
> @@ -1663,7 +1663,8 @@ build_v2_objc_method_fixup_call (int sup
>     method_params = tree_cons (NULL_TREE, lookup_object,
>                                tree_cons (NULL_TREE, selector,
>                                           method_params));
> -  t = build3 (OBJ_TYPE_REF, sender_cast, sender, lookup_object, size_zero_node);
> +  t = build3 (OBJ_TYPE_REF, sender_cast, sender, lookup_object,
> +	      build_int_cst (TREE_TYPE (lookup_object), 0));
>     ret_val =  build_function_call (input_location, t, method_params);
>     if (check_for_nil)
>       {
> @@ -1772,7 +1773,7 @@ build_v2_build_objc_method_call (int sup
>   
>     /* Build an obj_type_ref, with the correct cast for the method call.  */
>     t = build3 (OBJ_TYPE_REF, sender_cast, method,
> -			    lookup_object, size_zero_node);
> +	      lookup_object, build_int_cst (TREE_TYPE (lookup_object), 0));
>     tree ret_val = build_function_call_vec (loc, vNULL, t, parms, NULL);
>     vec_free (parms);
>     if (check_for_nil)
> --- gcc/testsuite/g++.dg/opt/pr101597.C.jj	2021-12-30 17:10:59.606117614 +0100
> +++ gcc/testsuite/g++.dg/opt/pr101597.C	2021-12-30 17:10:33.856477558 +0100
> @@ -0,0 +1,13 @@
> +// PR c++/101597
> +// { dg-do compile }
> +// { dg-options "-O2 -Warray-bounds" }
> +
> +typedef __SIZE_TYPE__ size_t;
> +struct S { virtual void *foo (size_t) __attribute__((alloc_size (2))); };
> +
> +int
> +foo (void *p)
> +{
> +  char *q = static_cast<char *> (static_cast<S *> (p)->foo (32));
> +  return q[64];		// { dg-warning "array subscript 64 is outside array bounds of" }
> +}
> 
> 	Jakub
>