Hi, Richard, This is the second patch, which is mainly the change for "Enable -Wuninitialized + -ftrivial-auto-var-init for address taken variables”.
Please see the detailed description below for the problem and solution of this patch. This patch has been bootstrapped and regressing tested on both X86 and aarch64. Okay for GCC12? thanks. Qing. ============================= Enable -Wuninitialized + -ftrivial-auto-var-init for address taken variables. With -ftrivial-auto-var-init, the address taken auto variable is replaced with a temporary variable during gimplification, and the original auto variable might be eliminated by compiler optimization completely. As a result, the current uninitialized warning analysis cannot get enough information from the IR, therefore the uninitialized warnings for address taken variable cannot be issued based on the current implemenation of -ftrival-auto-var-init. For more info please refer to: https://gcc.gnu.org/pipermail/gcc-patches/2021-August/577431.html In order to improve this situation, we can improve uninitialized analysis for address taken auto variables with -ftrivial-auto-var-init as following: for the following stmt: _1 = .DEFERRED_INIT (4, 2, &"alt_reloc"[0]); The original user variable has been eliminated from the IR, the LHS is the temporary variable that was created to replace it. we will get the necessary information from this stmt for reportinng the warning message: A. the name of the DECL from the 3rd parameter of the call; B. the location of the DECL from the location of the call; C. the LHS is used to hold the information on whether the warning has been issued or not to suppress warning messages when needed; The current testing cases for uninitialized warnings + -ftrivial-auto-var-init are adjusted to reflect the fact that we can issue warnings for address taken variables. gcc/ChangeLog: 2022-01-10 qing zhao <qing.z...@oracle.com> * tree-ssa-uninit.c (warn_uninit): Handle .DEFERRED_INIT call with an anonymous SSA_NAME specially. (check_defs): Likewise. (warn_uninit_phi_uses): Adjust the message format for warn_uninit. (warn_uninitialized_vars): Likewise. (warn_uninitialized_phi): Likewise. gcc/testsuite/ChangeLog: 2022-01-10 qing zhao <qing.z...@oracle.com> * gcc.dg/auto-init-uninit-16.c (testfunc): Delete xfail to reflect the fact that address taken variable can be warned. * gcc.dg/auto-init-uninit-34.c (warn_scalar_1): Likewise. (warn_scalar_2): Likewise. * gcc.dg/auto-init-uninit-37.c (T1): Likewise. (T2): Likewise. * gcc.dg/auto-init-uninit-B.c (baz): Likewise. — ********The complete patch is attached:
0002-Enable-Wuninitialized-ftrivial-auto-var-init-for-add.patch
Description: 0002-Enable-Wuninitialized-ftrivial-auto-var-init-for-add.patch
