https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113010
--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:901e7bdab70e2275723ac31dacbbce0b6f68f4f4 commit r14-9304-g901e7bdab70e2275723ac31dacbbce0b6f68f4f4 Author: Jakub Jelinek <ja...@redhat.com> Date: Mon Mar 4 19:23:02 2024 +0100 combine: Fix recent WORD_REGISTER_OPERATIONS check [PR113010] On Mon, Mar 04, 2024 at 05:18:39PM +0100, Rainer Orth wrote: > unfortunately, the patch broke Solaris/SPARC bootstrap > (sparc-sun-solaris2.11): > > .../gcc/combine.cc: In function 'rtx_code simplify_comparison(rtx_code, rtx_def**, rtx_def**)': > .../gcc/combine.cc:12101:25: error: '*(unsigned int*)((char*)&inner_mode + offsetof(scalar_int_mode, scalar_int_mode::m_mode))' may be used uninitialized [-Werror=maybe-uninitialized] > 12101 | scalar_int_mode mode, inner_mode, tmode; > | ^~~~~~~~~~ I don't see how it could ever work properly, inner_mode in that spot is just uninitialized. I think we shouldn't worry about paradoxical subregs of non-scalar_int_mode REGs/MEMs and for the scalar_int_mode ones should initialize inner_mode before we use it. Another option would be to use maybe_lt (GET_MODE_PRECISION (GET_MODE (SUBREG_REG (op0))), BITS_PER_WORD) and load_extend_op (GET_MODE (SUBREG_REG (op0))) == ZERO_EXTEND, or set machine_mode smode = GET_MODE (SUBREG_REG (op0)); and use it in those two spots. 2024-03-04 Jakub Jelinek <ja...@redhat.com> PR rtl-optimization/113010 * combine.cc (simplify_comparison): Guard the WORD_REGISTER_OPERATIONS check on scalar_int_mode of SUBREG_REG and initialize inner_mode.
