From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2153) id B7B383898505; Mon, 29 Nov 2021 08:49:42 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B7B383898505 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Jakub Jelinek To: gcc-cvs@gcc.gnu.org Subject: [gcc r11-9330] dwarf2out: Fix up field_byte_offset [PR101378] X-Act-Checkin: gcc X-Git-Author: Jakub Jelinek X-Git-Refname: refs/heads/releases/gcc-11 X-Git-Oldrev: 04d786a7add8f824af3b0c0d29884770810f7001 X-Git-Newrev: c479d98137fb589718570258547c6bea4f27d1d5 Message-Id: <20211129084942.B7B383898505@sourceware.org> Date: Mon, 29 Nov 2021 08:49:42 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 29 Nov 2021 08:49:42 -0000 https://gcc.gnu.org/g:c479d98137fb589718570258547c6bea4f27d1d5 commit r11-9330-gc479d98137fb589718570258547c6bea4f27d1d5 Author: Jakub Jelinek Date: Thu Nov 11 10:14:04 2021 +0100 dwarf2out: Fix up field_byte_offset [PR101378] For PCC_BITFIELD_TYPE_MATTERS field_byte_offset has quite large code to deal with it since many years ago (see it e.g. in GCC 3.2, although it used to be on HOST_WIDE_INTs, then on double_ints, now on offset_ints). But that code apparently isn't able to cope with members with empty class types with [[no_unique_address]] attribute, because the empty classes have non-zero type size but zero decl size and so one can end up from the computation with negative offset or offset 1 byte smaller than it should be. For !PCC_BITFIELD_TYPE_MATTERS, we just use tree_result = byte_position (decl); which seems exactly right even for the empty classes or anything which is not a bitfield (and for which we don't add DW_AT_bit_offset attribute). So, instead of trying to handle those no_unique_address members in the current already very complicated code, this limits it to bitfields. stor-layout.c PCC_BITFIELD_TYPE_MATTERS handling also affects only bitfields, twice it checks DECL_BIT_FIELD and once DECL_BIT_FIELD_TYPE. As discussed, this patch uses DECL_BIT_FIELD_TYPE check, because DECL_BIT_FIELD might be cleared for some bitfields with bitsizes multiple of BITS_PER_UNIT and e.g. struct S { int e; int a : 1, b : 7, c : 8, d : 16; } s; struct T { int a : 1, b : 7; long long c : 8; int d : 16; } t; int main () { s.c = 0x55; s.d = 0xaaaa; t.c = 0x55; t.d = 0xaaaa; s.e++; } has different debug info with DECL_BIT_FIELD check. 2021-11-11 Jakub Jelinek PR debug/101378 * dwarf2out.c (field_byte_offset): Do the PCC_BITFIELD_TYPE_MATTERS handling only for DECL_BIT_FIELD_TYPE decls. * g++.dg/debug/dwarf2/pr101378.C: New test. (cherry picked from commit 10db7573014008ff867098206f51012d501ab57b) Diff: --- gcc/dwarf2out.c | 1 + gcc/testsuite/g++.dg/debug/dwarf2/pr101378.C | 13 +++++++++++++ 2 files changed, 14 insertions(+) diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c index ae25eaccf70..d74c8e3867f 100644 --- a/gcc/dwarf2out.c +++ b/gcc/dwarf2out.c @@ -19443,6 +19443,7 @@ field_byte_offset (const_tree decl, struct vlr_context *ctx, properly dynamic byte offsets only when PCC bitfield type doesn't matter. */ if (PCC_BITFIELD_TYPE_MATTERS + && DECL_BIT_FIELD_TYPE (decl) && TREE_CODE (DECL_FIELD_OFFSET (decl)) == INTEGER_CST) { offset_int object_offset_in_bits; diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/pr101378.C b/gcc/testsuite/g++.dg/debug/dwarf2/pr101378.C new file mode 100644 index 00000000000..ec5e44df804 --- /dev/null +++ b/gcc/testsuite/g++.dg/debug/dwarf2/pr101378.C @@ -0,0 +1,13 @@ +// PR debug/101378 +// { dg-do compile { target c++11 } } +// { dg-options "-gdwarf-5 -dA" } +// { dg-final { scan-assembler-times "0\[^0-9x\\r\\n\]* DW_AT_data_member_location" 1 } } +// { dg-final { scan-assembler-times "1\[^0-9x\\r\\n\]* DW_AT_data_member_location" 1 } } +// { dg-final { scan-assembler-times "2\[^0-9x\\r\\n\]* DW_AT_data_member_location" 1 } } +// { dg-final { scan-assembler-not "-1\[^0-9x\\r\\n\]* DW_AT_data_member_location" } } + +struct E {}; +struct S +{ + [[no_unique_address]] E e, f, g; +} s;