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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/101062] [10/11/12 Regression] wrong code with "-O2 -fno-toplevel-reorder -frename-registers" Date: Fri, 18 Jun 2021 09:21:57 +0000 [thread overview] Message-ID: <bug-101062-4-uFy1Y9y59P@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-101062-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101062 --- Comment #16 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>: https://gcc.gnu.org/g:76e990fd211cbb20bf74ce074eb8b2d7b096d3b7 commit r12-1640-g76e990fd211cbb20bf74ce074eb8b2d7b096d3b7 Author: Jakub Jelinek <jakub@redhat.com> Date: Fri Jun 18 11:20:40 2021 +0200 stor-layout: Don't create DECL_BIT_FIELD_REPRESENTATIVE for QUAL_UNION_TYPE [PR101062] > The following patch does create them, but treats all such bitfields as if > they were in a structure where the particular bitfield is the only field. While the patch passed bootstrap/regtest on the trunk, when trying to backport it to 11 branch the bootstrap failed with atree.ads:3844:34: size for "Node_Record" too small errors. Turns out the error is not about size being too small, but actually about size being non-constant, and comes from: /* In a FIELD_DECL of a RECORD_TYPE, this is a pointer to the storage representative FIELD_DECL. */ #define DECL_BIT_FIELD_REPRESENTATIVE(NODE) \ (FIELD_DECL_CHECK (NODE)->field_decl.qualifier) /* For a FIELD_DECL in a QUAL_UNION_TYPE, records the expression, which if nonzero, indicates that the field occupies the type. */ #define DECL_QUALIFIER(NODE) (FIELD_DECL_CHECK (NODE)->field_decl.qualifier) so by setting up DECL_BIT_FIELD_REPRESENTATIVE in QUAL_UNION_TYPE we actually set or modify DECL_QUALIFIER and then construct size as COND_EXPRs with those bit field representatives (e.g. with array type) as conditions which doesn't fold into constant. The following patch fixes it by not creating DECL_BIT_FIELD_REPRESENTATIVEs for QUAL_UNION_TYPE as there is nowhere to store them, Shall we change tree.h to document that DECL_BIT_FIELD_REPRESENTATIVE is valid also on UNION_TYPE? I see: tree-ssa-alias.c- if (TREE_CODE (type1) == RECORD_TYPE tree-ssa-alias.c: && DECL_BIT_FIELD_REPRESENTATIVE (field1)) tree-ssa-alias.c: field1 = DECL_BIT_FIELD_REPRESENTATIVE (field1); tree-ssa-alias.c- if (TREE_CODE (type2) == RECORD_TYPE tree-ssa-alias.c: && DECL_BIT_FIELD_REPRESENTATIVE (field2)) tree-ssa-alias.c: field2 = DECL_BIT_FIELD_REPRESENTATIVE (field2); Shall we change that to || == UNION_TYPE or do we assume all fields are overlapping in a UNION_TYPE already? At other spots (asan, ubsan, expr.c) it is unclear what will happen if they see a QUAL_UNION_TYPE with a DECL_QUALIFIER (or does the Ada FE lower that somehow)? 2021-06-18 Jakub Jelinek <jakub@redhat.com> PR middle-end/101062 * stor-layout.c (finish_bitfield_layout): Don't add bitfield representatives in QUAL_UNION_TYPE.
next prev parent reply other threads:[~2021-06-18 9:21 UTC|newest] Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-14 11:05 [Bug tree-optimization/101062] New: " suochenyao at 163 dot com 2021-06-14 18:04 ` [Bug tree-optimization/101062] [10/11/12 Regression] " jakub at gcc dot gnu.org 2021-06-14 18:08 ` jakub at gcc dot gnu.org 2021-06-14 18:35 ` jakub at gcc dot gnu.org 2021-06-14 18:59 ` jakub at gcc dot gnu.org 2021-06-14 20:20 ` jakub at gcc dot gnu.org 2021-06-14 21:46 ` ebotcazou at gcc dot gnu.org 2021-06-15 7:42 ` rguenth at gcc dot gnu.org 2021-06-15 8:15 ` jakub at gcc dot gnu.org 2021-06-15 8:56 ` [Bug middle-end/101062] " rguenther at suse dot de 2021-06-15 9:05 ` jakub at gcc dot gnu.org 2021-06-15 9:21 ` rguenth at gcc dot gnu.org 2021-06-16 10:18 ` cvs-commit at gcc dot gnu.org 2021-06-17 8:20 ` jakub at gcc dot gnu.org 2021-06-17 8:22 ` jakub at gcc dot gnu.org 2021-06-17 9:13 ` ebotcazou at gcc dot gnu.org 2021-06-18 9:21 ` cvs-commit at gcc dot gnu.org [this message] 2021-06-18 9:23 ` cvs-commit at gcc dot gnu.org 2021-06-18 9:23 ` cvs-commit at gcc dot gnu.org 2021-07-13 13:13 ` [Bug middle-end/101062] [10 " jakub at gcc dot gnu.org 2022-05-10 8:18 ` cvs-commit at gcc dot gnu.org 2022-05-10 8:19 ` cvs-commit at gcc dot gnu.org 2022-05-11 6:20 ` cvs-commit at gcc dot gnu.org 2022-05-11 6:20 ` cvs-commit at gcc dot gnu.org 2022-05-11 6:36 ` jakub at gcc dot gnu.org
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