From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 24969 invoked by alias); 4 Jul 2014 12:02:15 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 24847 invoked by uid 48); 4 Jul 2014 12:02:08 -0000 From: "ubizjak at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/61656] Undefined behavior in classify_argument Date: Fri, 04 Jul 2014 12:02:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Version: 4.10.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: ubizjak at gmail dot com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-07/txt/msg00268.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D61656 --- Comment #1 from Uro=C5=A1 Bizjak --- (In reply to Jakub Jelinek from comment #0) > /usr/src/gcc/obj052/gcc/xgcc -B/usr/src/gcc/obj052/gcc/ > -fno-diagnostics-show-caret -fdiagnostics-color=3Dnever -O0 -w -c -o pr4 > 2025-2.o /usr/src/gcc/gcc/testsuite/gcc.c-torture/compile/pr42025-2.c > ../../gcc/config/i386/i386.c:6583:60: runtime error: mload of value 32669, > which is not a valid value for type 'x86_64_reg_class' >=20 > This is on passing > typedef struct { void *p; } Ptr; > struct A { int i; union { Ptr p; char *q; } u; }; > by value and the problem is that when processing the union with bit_offset > 64, > words is 1 (u is DImode 64-bit field), but when we recurse, we are called > with > 64-bit scalar DImode q and bit_offset 64, that is size (128-1)&0x7f and so > it is the size < 64+64 case where we return 2 and { X86_64_INTEGER_CLASS, > X86_64_INTEGER_CLASS }; in subclauses. But words is 1 and we merge class= es > up to num (2). A simple fix could be: > if (!num) > return 0; > - for (i =3D 0; i < num; i++) > + for (i =3D 0; i < num && i < words; i++) > classes[i] =3D merge_classes (subclasses[i], classes[i]); > in the UNION_TYPE case, as it seems the caller will not care about classes > above returned number (words). I'd hope such a patch should not change t= he > ABI even. > I don't know whether there isn't an ABI problem related to this though, s= ay > if at bit_offset 64 we have just SImode field in the union rather than > DImode, > then I'd guess the recursive call would give us { X86_64_INTEGER_CLASS, > X86_64_INTEGERSI_CLASS }; but we'd use X86_64_INTEGER_CLASS anyway, as we > are looking at position 0, not 1. X86_64_INTEGER_CLASS and X86_64_INTEGERSI_CLASS are handled in the same way, the only difference is that the later class allows/uses cheaper movl insn. = So, if a SImode value lives at bit_offset 64, the change from INTEGER_CLASS to INTEGERSI_CLASS does NOT introduce an ABI change - movl just narrows memory load and sets "don't care" high bits to zero. >>From gcc-bugs-return-455678-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Fri Jul 04 12:21:58 2014 Return-Path: Delivered-To: listarch-gcc-bugs@gcc.gnu.org Received: (qmail 13185 invoked by alias); 4 Jul 2014 12:21:57 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Delivered-To: mailing list gcc-bugs@gcc.gnu.org Received: (qmail 13092 invoked by uid 48); 4 Jul 2014 12:21:47 -0000 From: "matz at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/61203] [4.8/4.9/4.10 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline Date: Fri, 04 Jul 2014 12:21:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 4.10.0 X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: matz at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.8.4 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-07/txt/msg00269.txt.bz2 Content-length: 917 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61203 --- Comment #3 from Michael Matz --- (In reply to Jakub Jelinek from comment #2) > same spot. No idea what to do against this though, treating a CLOBBER as a > barrier for propagation of addresses to other local variables would penalize > stuff way too much. Conceptually this should be the right thing. The clobber says the object doesn't exist anymore, so also forming its address should be invalid/implementation defined. Either the clobber should move or it should be a barrier also for addresses of the clobbered object. I'm not sure if that really would penalize much. > And giving up on stack slot sharing because of such an > artificial testcase is not useful either. Perhaps expansion could detect the situation (address of clobbered object leaked after the clobber) and disable sharing just for such problematic objects.