From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 4D7E83858D1E; Tue, 26 Apr 2022 12:08:30 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4D7E83858D1E From: "364961 at mail dot ru" To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/105393] New: A simple for loop becomes an infinite when -O1/2/3 used Date: Tue, 26 Apr 2022 12:08:29 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: c++ X-Bugzilla-Version: 10.2.1 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: 364961 at mail dot ru X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: 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: bug_id short_desc product version bug_status bug_severity priority component assigned_to reporter target_milestone attachments.created Message-ID: 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-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 26 Apr 2022 12:08:30 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105393 Bug ID: 105393 Summary: A simple for loop becomes an infinite when -O1/2/3 used Product: gcc Version: 10.2.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: 364961 at mail dot ru Target Milestone: --- Created attachment 52884 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D52884&action=3Dedit the preprocessed bug's source file The main function calls a function with a for loop inside. The called funct= ion is declared like boolean, but in fact doesn't return any result. In this ca= se the for=20 loop becomes infinite when any optimisation used. But if: - disable an optimisation; - return boolean result; - declare the function as void. The behaviour will become correct. It looks like the bug 49218, but a litt= le bit different.=20 build row: g++ -O2 -std=3Dc++11 -c main.cpp main.o the compiler output: main.cpp: In function =E2=80=98bool initAllBuffers()=E2=80=99:=20=20=20=20= =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= =20=20=20=20 =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= =20=20=20=20 =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20 aleksandr@workHost:~/work/multaleksandr@workHost:~/work/multex/ main.cpp:47:1: warning: no return statement in function returning non-void [-Wreturn-type]=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20 =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= =20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20 aleksandr@workHost:~/work/mulaleksandr@workHost:~/work/multex/a 47 | }=20=20=20=20=20=20=20=20=20=20=20=20=20=20 g++ -v Using built-in specs. COLLECT_GCC=3Dg++ COLLECT_LTO_WRAPPER=3D/usr/lib/gcc/x86_64-linux-gnu/10/lto-wrapper OFFLOAD_TARGET_NAMES=3Dnvptx-none:amdgcn-amdhsa:hsa OFFLOAD_TARGET_DEFAULT=3D1 Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion=3D'Debian 10.2.1-6' --with-bugurl=3Dfile:///usr/share/doc/gcc-10/README.Bugs --enable-languages=3Dc,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix= =3D/usr --with-gcc-major-version-only --program-suffix=3D-10 --program-prefix=3Dx86_64-linux-gnu- --enable-shared --enable-linker-build= -id --libexecdir=3D/usr/lib --without-included-gettext --enable-threads=3Dposix --libdir=3D/usr/lib --enable-nls --enable-bootstrap --enable-clocale=3Dgnu --enable-libstdcxx-debug --enable-libstdcxx-time=3Dyes --with-default-libstdcxx-abi=3Dnew --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=3Drelease --with-target-system-zlib=3Dauto --enable-objc-gc=3Dauto --enable-multiarch --disable-werror --with-arch-32= =3Di686 --with-abi=3Dm64 --with-multilib-list=3Dm32,m64,mx32 --enable-multilib --with-tune=3Dgeneric --enable-offload-targets=3Dnvptx-none=3D/build/gcc-10-Km9U7s/gcc-10-10.2.1/= debian/tmp-nvptx/usr,amdgcn-amdhsa=3D/build/gcc-10-Km9U7s/gcc-10-10.2.1/deb= ian/tmp-gcn/usr,hsa --without-cuda-driver --enable-checking=3Drelease --build=3Dx86_64-linux-g= nu --host=3Dx86_64-linux-gnu --target=3Dx86_64-linux-gnu --with-build-config=3Dbootstrap-lto-lean --enable-link-mutex Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 10.2.1 20210110 (Debian 10.2.1-6)=