On Sat, Dec 18, 2021 at 06:05:09PM +0530, Siddhesh Poyarekar wrote:
> @@ -1440,6 +1441,53 @@ cond_expr_object_size (struct object_size_info *osi,
> tree var, gimple *stmt)
> return reexamine;
> }
>
> +/* Find size of an object passed as a parameter to the function. */
> +
> +static void
> +parm_object_size (struct object_size_info *osi, tree var)
> +{
> + int object_size_type = osi->object_size_type;
> + tree parm = SSA_NAME_VAR (var);
> +
> + if (!(object_size_type & OST_DYNAMIC) || !POINTER_TYPE_P (TREE_TYPE
> (parm)))
> + expr_object_size (osi, var, parm);
This looks very suspicious. Didn't you mean { expr_object_size (...); return;
} here?
Because the code below e.g. certainly assumes OST_DYNAMIC and that TREE_TYPE
(parm)
is a pointer type (otherwise TREE_TYPE (TREE_TYPE (...) wouldn't work.
> +
> + /* Look for access attribute. */
> + rdwr_map rdwr_idx;
> +
> + tree fndecl = cfun->decl;
> + const attr_access *access = get_parm_access (rdwr_idx, parm, fndecl);
> + tree typesize = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (parm)));
> + tree sz = NULL_TREE;
> +
> + if (access && access->sizarg != UINT_MAX)
Perhaps && typesize here? It makes no sense to e.g. create ssa default def
when you aren't going to use it in any way.
> + {
> + tree fnargs = DECL_ARGUMENTS (fndecl);
> + tree arg = NULL_TREE;
> + unsigned argpos = 0;
> +
> + /* Walk through the parameters to pick the size parameter and safely
> + scale it by the type size. */
> + for (arg = fnargs; argpos != access->sizarg && arg;
> + arg = TREE_CHAIN (arg), ++argpos);
Instead of a loop with empty body wouldn't it be better to
do the work in that for loop?
I.e. take argpos != access->sizarg && from the condition,
replace arg != NULL_TREE with that argpos == access->sizarg
and add a break;?
> +
> + if (arg != NULL_TREE && INTEGRAL_TYPE_P (TREE_TYPE (arg)))
> + {
> + sz = get_or_create_ssa_default_def (cfun, arg);
Also, I must say I'm little bit worried about this
get_or_create_ssa_default_def call. If the SSA_NAME doesn't exist,
so you create it and then attempt to use it but in the end don't
because e.g. some PHI's another argument was unknown etc., will
that SSA_NAME be released through release_ssa_name?
I think GIMPLE is fairly unhappy if there are SSA_NAMEs created and not
released that don't appear in the IL anywhere.
> + if (sz != NULL_TREE)
> + {
> + sz = fold_convert (sizetype, sz);
> + if (typesize)
> + sz = size_binop (MULT_EXPR, sz, typesize);
> + }
> + }
> + }
Jakub
