Hi Cupertino,
On 4/18/24 13:58, Cupertino Miranda wrote:
> Hi David, everyone,
>
> Following Davids last review I decided to properly detect error cases,
> as suggested.
> The error however should be reported earlier in compilation in
> pack_enum_valud function, where all the errors are reported.
>
> Thanks for the quick and detailed reviews.
>
> Regards,
> Cupertino
Thanks for taking the time on this.
This version is nice, just one little comment:
>
> The BPF backend was allocating an unnecessarily large string when
> constructing CO-RE relocations for enum types.
> This patch further verifies if an enumerator is valid for CO-RE
> representability and returns an error in those cases.
The second sentence is a little awkward and seems to imply the error is
returned when the enumerator is valid :)
Perhaps "...verifies that an enumerator is valid for CO-RE, and returns
an error if it is not" or similar would be more clear?
Otherwise, OK.
Thanks!
>
> gcc/ChangeLog:
> * config/bpf/core-builtins.cc (get_index_for_enum_value): Create
> function.
> (pack_enum_value): Check for enumerator and error out.
> (process_enum_value): Correct string allocation.
> ---
> gcc/config/bpf/core-builtins.cc | 57 ++++++++++++++++++++++-----------
> 1 file changed, 38 insertions(+), 19 deletions(-)
>
> diff --git a/gcc/config/bpf/core-builtins.cc b/gcc/config/bpf/core-builtins.cc
> index e03e986e2c1..829acea98f7 100644
> --- a/gcc/config/bpf/core-builtins.cc
> +++ b/gcc/config/bpf/core-builtins.cc
> @@ -795,6 +795,23 @@ process_field_expr (struct cr_builtins *data)
> static GTY(()) hash_map<tree, tree> *bpf_enum_mappings;
> tree enum_value_type = NULL_TREE;
>
> +static int
> +get_index_for_enum_value (tree type, tree expr)
> +{
> + gcc_assert (TREE_CODE (expr) == CONST_DECL
> + && TREE_CODE (type) == ENUMERAL_TYPE);
> +
> + unsigned int index = 0;
> + for (tree l = TYPE_VALUES (type); l; l = TREE_CHAIN (l))
> + {
> + gcc_assert (index < (1 << 16));
> + if (TREE_VALUE (l) == expr)
> + return index;
> + index++;
> + }
> + return -1;
> +}
> +
> /* Pack helper for the __builtin_preserve_enum_value. */
>
> static struct cr_local
> @@ -846,6 +863,16 @@ pack_enum_value_fail:
> ret.reloc_data.default_value = integer_one_node;
> }
>
> + if (ret.fail == false )
> + {
> + int index = get_index_for_enum_value (type, tmp);
> + if (index == -1 || index >= (1 << 16))
> + {
> + bpf_error ("enum value in CO-RE builtin cannot be represented");
> + ret.fail = true;
> + }
> + }
> +
> ret.reloc_data.type = type;
> ret.reloc_data.kind = kind;
> return ret;
> @@ -864,25 +891,17 @@ process_enum_value (struct cr_builtins *data)
>
> struct cr_final ret = { NULL, type, data->kind };
>
> - if (TREE_CODE (expr) == CONST_DECL
> - && TREE_CODE (type) == ENUMERAL_TYPE)
> - {
> - unsigned int index = 0;
> - for (tree l = TYPE_VALUES (type); l; l = TREE_CHAIN (l))
> - {
> - if (TREE_VALUE (l) == expr)
> - {
> - char *tmp = (char *) ggc_alloc_atomic ((index / 10) + 1);
> - sprintf (tmp, "%d", index);
> - ret.str = (const char *) tmp;
> -
> - break;
> - }
> - index++;
> - }
> - }
> - else
> - gcc_unreachable ();
> + gcc_assert (TREE_CODE (expr) == CONST_DECL
> + && TREE_CODE (type) == ENUMERAL_TYPE);
> +
> + int index = get_index_for_enum_value (type, expr);
> + gcc_assert (index != -1 && index < (1 << 16));
> +
> + /* Index can only be a value up to 2^16. Should always fit
> + in 6 chars. */
> + char tmp[6];
> + sprintf (tmp, "%u", index);
> + ret.str = CONST_CAST (char *, ggc_strdup(tmp));
>
> return ret;
> }
