Re: [patch for gcc12 stage1][version 2] add -ftrivial-auto-var-init and variable attribute "uninitialized" to gcc

[Qing Zhao <QING.ZHAO@ORACLE.COM>]

Ping

> On Mar 24, 2021, at 4:21 PM, Qing Zhao via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> 
> Hi, 
> 
> This is the 2nd version of the patch for the new security feature for GCC.
> 
> Could you please take a look at it and let me know any comments and issues.
> 
> Thanks.
> 
> Qing
> 
> ******compared to Version 1, this version added the following new features to address Kees’s comments:
> 
> 1.  correctly handle VLA inside a structure for pattern initialization.
> In tree.c (build_pattern_cst):
> 
> +           /* if the field is a variable length array, it should be the last
> +              field of the record, and no need to initialize.  */
> +           if (TREE_CODE (TREE_TYPE (field)) == ARRAY_TYPE
> +               && TYPE_SIZE (TREE_TYPE (field)) == NULL_TREE
> +               && ((TYPE_DOMAIN (TREE_TYPE (field)) != NULL_TREE
> +                   && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (field)))
> +                                      == NULL_TREE)
> +                  || TYPE_DOMAIN (TREE_TYPE (field)) == NULL_TREE))
> +             continue;
> 
> 2.  initialize all paddings to zero when -ftrivial-auto-var-init is present.
> In expr.c (store_constructor):
> 
>         Clear the whole structure when
>         -ftrivial-auto-var-init and the structure has paddings.
> 
> In gimplify.c (gimplify_init_constructor):
> 
>         Clear the whole structure when
>         -ftrivial-auto-var-init and the structure has paddings.
> 
> As agreed with Kees, treat the issue related to auto variables outside of the cases and inside the switch as a low priority one. 
> 
> 3. Add  the following new testing cases for the above 1 and 2:
> 
>         * c-c++-common/auto-init-13.c: New test.
>         * c-c++-common/auto-init-14.c: New test. 
> 
>         * gcc.target/aarch64/auto-init-9.c: New test.
>         * gcc.target/aarch64/auto-init-10.c: New test.
>         * gcc.target/aarch64/auto-init-11.c: New test.
>         * gcc.target/aarch64/auto-init-12.c: New test.
>         * gcc.target/aarch64/auto-init-13.c: New test.
>         * gcc.target/aarch64/auto-init-14.c: New test.
>         * gcc.target/aarch64/auto-init-15.c: New test.
>         * gcc.target/aarch64/auto-init-16.c: New test.
>         * gcc.target/aarch64/auto-init-17.c: New test.
>         * gcc.target/aarch64/auto-init-18.c: New test.
>         * gcc.target/aarch64/auto-init-19.c: New test.
>         * gcc.target/aarch64/auto-init-20.c: New test.
> 
>         * gcc.target/i386/auto-init-9.c: New test.
>         * gcc.target/i386/auto-init-10.c: New test.
>         * gcc.target/i386/auto-init-11.c: New test.
>         * gcc.target/i386/auto-init-12.c: New test.
>         * gcc.target/i386/auto-init-13.c: New test.
>         * gcc.target/i386/auto-init-14.c: New test.
>         * gcc.target/i386/auto-init-15.c: New test.
>         * gcc.target/i386/auto-init-16.c: New test.
>         * gcc.target/i386/auto-init-17.c: New test.
>         * gcc.target/i386/auto-init-18.c: New test.
>         * gcc.target/i386/auto-init-19.c: New test.
>         * gcc.target/i386/auto-init-20.c: New test.
> 
> 4. Update the default approach as D,  then when specify -ftrivial-auto-var-init,  the default approach is the “.DEFERRED_INIT” 
> Approach. No need to add -fauto-var-init-approach=D anymore.
> 
> If we need to compare approach A and D, we can add -fauto-var-init-approach=A to get that implementation. 
> 
> 5.  Delete all -fauto-var-init-approach=D in the testing cases. 
> 
> ****** others are the same as Version 1, please see the version 1 description at:
> 
> https://gcc.gnu.org/pipermail/gcc-patches/2021-February/565581.html <https://gcc.gnu.org/pipermail/gcc-patches/2021-February/565581.html>
> 
> 
> *******Changelog:
> 
> gcc/:
> 
> 2021-03-24  qing zhao  <qing.zhao@oracle.com>
> 
>         * common.opt (ftrivial-auto-var-init=): New.
>         (fauto-var-init-approach=): Likewise.
>         * doc/extend.texi: Document the uninitialized attribute.
>         * doc/invoke.texi: Document -ftrivial-auto-var-init.
>         * expr.c (store_constructor): Clear the whole structure when
>         -ftrivial-auto-var-init and the structure has paddings.
>         * flag-types.h (enum auto_init_type): New enumerated type
>         auto_init_type.
>         (enum auto_init_approach): New enumerated type auto_init_approach.
>         * gimple.h (enum gf_mask): Add GF_CALL_MEMSET_FOR_UNINIT case.
>         (gimple_call_set_memset_for_uninit): New function.
>         (gimple_call_memset_for_uninit_p): Likewise.
>         * gimplify.c (gimplify_vla_decl): Add initialization to vla per users'
>         requests. 
>         (build_deferred_init): New function.
>         (gimple_add_init_for_auto_var): Likewise.
>         (gimplify_decl_expr): Add initialization to automatic variables per
>         users' requests.
>         (gimplify_init_constructor): Clear the whole structure when
>         -ftrivial-auto-var-init and the structure has paddings.
>         * internal-fn.c (expand_DEFERRED_INIT): New function.
>         * internal-fn.def (DEFERRED_INIT): New internal function.
>         * tree-cfg.c (verify_gimple_call): Skip calls to DEFERRED_INIT.
>         * tree-core.h (tree_decl_with_vis): Add uninitialized field.
>         * tree-sra.c (sra_stats): Add two new fields deferred_init and
>         subtree_deferred_init.
>         (generate_subtree_deferred_init): New function.
>         (sra_modify_deferred_init): Likewise.
>         (sra_modify_function_body): Handle calls to DEFERRED_INIT specially.
>         * tree-ssa-structalias.c (find_func_aliases_for_deferred_init): New
>         function.
>         (find_func_aliases_for_call): Handle calls to DEFERRED_INIT specially.
>         * tree-ssa-uninit.c (warn_uninit): Handle calls to DEFERRED_INIT
>         specially.
>         (check_defs): Handle calls to DEFERRED_INIT and MEMSET for uninitialized
>         variable specially.
>         (warn_uninitialized_vars): Handle calls to DEFERRED_INIT specially.
>         * tree-ssa.c (ssa_undefined_value_p): Handle calls to DEFERRED_INIT
>         specially.
>         * tree.c (build_pattern_cst): New function.
>         (type_has_padding): Likewise.
>         * tree.h (DECL_UNINITIALIZED): New macro.
>         (build_pattern_cst): New declaration.
>         (type_has_padding): Likewise.
> 
> gcc/c-family/:
> 
> 2021-03-24  qing zhao  <qing.zhao@oracle.com>
> 
>         * c-attribs.c (handle_uninitialized_attribute): New function.
>         (c_common_attribute_table): Add "uninitialized" attribute.
> 
> gcc/testsuite/:
> 
> 2021-03-24  qing zhao  <qing.zhao@oracle.com>
> 
>         * c-c++-common/auto-init-1.c: New test.
>         * c-c++-common/auto-init-10.c: New test.
>         * c-c++-common/auto-init-11.c: New test.
>         * c-c++-common/auto-init-12.c: New test.
>         * c-c++-common/auto-init-13.c: New test.
>         * c-c++-common/auto-init-14.c: New test.
>         * c-c++-common/auto-init-2.c: New test.
>         * c-c++-common/auto-init-3.c: New test.
>         * c-c++-common/auto-init-4.c: New test.
>         * c-c++-common/auto-init-5.c: New test.
>         * c-c++-common/auto-init-6.c: New test.
>         * c-c++-common/auto-init-7.c: New test.
>         * c-c++-common/auto-init-8.c: New test.
>         * c-c++-common/auto-init-9.c: New test.
>         * c-c++-common/auto-init-esra.c: New test.
>         * g++.dg/auto-init-uninit-pred-1_a.C: New test.
>         * g++.dg/auto-init-uninit-pred-1_b.C: New test.
>         * g++.dg/auto-init-uninit-pred-2_a.C: New test.
>         * g++.dg/auto-init-uninit-pred-2_b.C: New test.
>         * g++.dg/auto-init-uninit-pred-3_a.C: New test.
>         * g++.dg/auto-init-uninit-pred-3_b.C: New test.
>         * g++.dg/auto-init-uninit-pred-4.C: New test.
>         * g++.dg/auto-init-uninit-pred-loop-1_a.cc: New test.
>         * g++.dg/auto-init-uninit-pred-loop-1_b.cc: New test.
>         * g++.dg/auto-init-uninit-pred-loop-1_c.cc: New test.
>         * g++.dg/auto-init-uninit-pred-loop_1.cc: New test.
>         * gcc.dg/auto-init-uninit-1.c: New test.
>         * gcc.dg/auto-init-uninit-11.c: New test.
>         * gcc.dg/auto-init-uninit-12.c: New test.
>         * gcc.dg/auto-init-uninit-13.c: New test.
>         * gcc.dg/auto-init-uninit-14.c: New test.
>         * gcc.dg/auto-init-uninit-15.c: New test.
>         * gcc.dg/auto-init-uninit-16.c: New test.
>         * gcc.dg/auto-init-uninit-17.c: New test.
>         * gcc.dg/auto-init-uninit-18.c: New test.
>         * gcc.dg/auto-init-uninit-19.c: New test.
>         * gcc.dg/auto-init-uninit-2.c: New test.
>         * gcc.dg/auto-init-uninit-20.c: New test.
>         * gcc.dg/auto-init-uninit-21.c: New test.
>         * gcc.dg/auto-init-uninit-22.c: New test.
>         * gcc.dg/auto-init-uninit-23.c: New test.
>         * gcc.dg/auto-init-uninit-24.c: New test.
>         * gcc.dg/auto-init-uninit-25.c: New test.
>         * gcc.dg/auto-init-uninit-26.c: New test.
>         * gcc.dg/auto-init-uninit-3.c: New test.
>         * gcc.dg/auto-init-uninit-34.c: New test.
>         * gcc.dg/auto-init-uninit-36.c: New test.
>         * gcc.dg/auto-init-uninit-37.c: New test.
>         * gcc.dg/auto-init-uninit-4.c: New test.
>         * gcc.dg/auto-init-uninit-5.c: New test.
>         * gcc.dg/auto-init-uninit-6.c: New test.
>         * gcc.dg/auto-init-uninit-8.c: New test.
>         * gcc.dg/auto-init-uninit-9.c: New test.
>         * gcc.dg/auto-init-uninit-A.c: New test.
>         * gcc.dg/auto-init-uninit-B.c: New test.
>         * gcc.dg/auto-init-uninit-C.c: New test.
>         * gcc.dg/auto-init-uninit-H.c: New test.
>         * gcc.dg/auto-init-uninit-I.c: New test.
>         * gcc.target/aarch64/auto-init-1.c: New test.
>         * gcc.target/aarch64/auto-init-10.c: New test.
>         * gcc.target/aarch64/auto-init-11.c: New test.
>         * gcc.target/aarch64/auto-init-12.c: New test.
>         * gcc.target/aarch64/auto-init-13.c: New test.
>         * gcc.target/aarch64/auto-init-14.c: New test.
>         * gcc.target/aarch64/auto-init-15.c: New test.
>         * gcc.target/aarch64/auto-init-16.c: New test.
>         * gcc.target/aarch64/auto-init-17.c: New test.
>         * gcc.target/aarch64/auto-init-18.c: New test.
>         * gcc.target/aarch64/auto-init-19.c: New test.
>         * gcc.target/aarch64/auto-init-2.c: New test.
>         * gcc.target/aarch64/auto-init-20.c: New test.
>         * gcc.target/aarch64/auto-init-3.c: New test.
>         * gcc.target/aarch64/auto-init-4.c: New test.
>         * gcc.target/aarch64/auto-init-5.c: New test.
>         * gcc.target/aarch64/auto-init-6.c: New test.
>         * gcc.target/aarch64/auto-init-7.c: New test.
>         * gcc.target/aarch64/auto-init-8.c: New test.
>         * gcc.target/aarch64/auto-init-9.c: New test.
>         * gcc.target/i386/auto-init-1.c: New test.
>         * gcc.target/i386/auto-init-10.c: New test.
>         * gcc.target/i386/auto-init-11.c: New test.
>         * gcc.target/i386/auto-init-12.c: New test.
>         * gcc.target/i386/auto-init-13.c: New test.
>         * gcc.target/i386/auto-init-14.c: New test.
>         * gcc.target/i386/auto-init-15.c: New test.
>         * gcc.target/i386/auto-init-16.c: New test.
>         * gcc.target/i386/auto-init-17.c: New test.
>         * gcc.target/i386/auto-init-18.c: New test.
>         * gcc.target/i386/auto-init-19.c: New test.
>         * gcc.target/i386/auto-init-2.c: New test.
>         * gcc.target/i386/auto-init-20.c: New test.
>         * gcc.target/i386/auto-init-3.c: New test.
>         * gcc.target/i386/auto-init-4.c: New test.
>         * gcc.target/i386/auto-init-5.c: New test.
>         * gcc.target/i386/auto-init-6.c: New test.
>         * gcc.target/i386/auto-init-7.c: New test.
>         * gcc.target/i386/auto-init-8.c: New test.
>         * gcc.target/i386/auto-init-9.c: New test.
> 
> ******The complete patch is attached as following:
> 
> 
> 
> <0001-add-ftrivial-auto-var-init-and-variable-attribute-un.patch>