From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id D939A3858D33; Fri, 3 Mar 2023 06:40:57 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org D939A3858D33 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1677825657; bh=HCeW5744st8k+XnagVO1NVJbGnbP1mu8oo4l6Q7Ords=; h=From:To:Subject:Date:From; b=vPfQjaDP8IKXrn6MOquV8WKrG45v9JHYU4ZbZD+R76a+nVU58begR4uSAL5QJViRo rH72Ukwg64W5tDElqECgyB6/MlzQK7GCA/o/6zrf1uSgqaPVszBciUMwQYFzMFyGw7 rEpZddD2gRBjtkHp2bYRBAMB72zUL5kQio1dJW7k= From: "akihiko.odaki at daynix dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/109002] New: -O1 -ftree-pre -ftree-partial-pre results in stall value Date: Fri, 03 Mar 2023 06:40:57 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 13.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: akihiko.odaki at daynix dot com 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 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 List-Id: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109002 Bug ID: 109002 Summary: -O1 -ftree-pre -ftree-partial-pre results in stall value Product: gcc Version: 13.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: akihiko.odaki at daynix dot com Target Milestone: --- The following should emit an executable which prints "a" forever, but the actual compiled executable prints nothing and just hangs. It seems the code sees a stall value of variable g. gcc -O1 -ftree-pre -ftree-partial-pre -x c - < int g; int h; int main(void) { for (int i =3D 0; ; i++) { for (int j =3D 0; j < g; j++); if (i & 1) { if (h) continue; if (g) puts("a"); g =3D 1; } } } EOF I reproduced this bug with the current master. gcc -v says: Using built-in specs. COLLECT_GCC=3D/home/alarm/gcc-installation/usr/local/bin/gcc COLLECT_LTO_WRAPPER=3D/home/alarm/gcc-installation/usr/local/bin/../libexec= /gcc/aarch64-unknown-linux-gnu/13.0.1/lto-wrapper Target: aarch64-unknown-linux-gnu Configured with: ../gcc/configure --disable-bootstrap : (reconfigured) ../gcc/configure --disable-bootstrap Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 13.0.1 20230302 (experimental) (GCC)=20 COLLECT_GCC_OPTIONS=3D'-v' '-mlittle-endian' '-mabi=3Dlp64' /home/alarm/gcc-installation/usr/local/bin/../libexec/gcc/aarch64-unknown-l= inux-gnu/13.0.1/cc1 -quiet -v -iprefix /home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch64-unknown-linux= -gnu/13.0.1/ /home/alarm/a.c -quiet -dumpbase a.c -dumpbase-ext .c -mlittle-endian -mabi=3Dlp64 -version -o /tmp/ccetU9yt.s GNU C17 (GCC) version 13.0.1 20230302 (experimental) (aarch64-unknown-linux-gnu) compiled by GNU C version 12.1.0, GMP version 6.2.1, MPFR version 4.2.0, MPC version 1.3.1, isl version isl-0.25-GMP GGC heuristics: --param ggc-min-expand=3D30 --param ggc-min-heapsize=3D4096 ignoring nonexistent directory "/home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch64-unknown-linu= x-gnu/13.0.1/../../../../aarch64-unknown-linux-gnu/include" ignoring duplicate directory "/home/alarm/gcc-installation/usr/local/bin/../lib/gcc/../../lib/gcc/aarch6= 4-unknown-linux-gnu/13.0.1/include" ignoring duplicate directory "/home/alarm/gcc-installation/usr/local/bin/../lib/gcc/../../lib/gcc/aarch6= 4-unknown-linux-gnu/13.0.1/include-fixed" ignoring nonexistent directory "/home/alarm/gcc-installation/usr/local/bin/../lib/gcc/../../lib/gcc/aarch6= 4-unknown-linux-gnu/13.0.1/../../../../aarch64-unknown-linux-gnu/include" #include "..." search starts here: #include <...> search starts here: /home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch64-unknown-linux= -gnu/13.0.1/include /home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch64-unknown-linux= -gnu/13.0.1/include-fixed /usr/local/include /usr/include End of search list. Compiler executable checksum: 374b2759695ed1b72f52cb0f1847fbb3 COLLECT_GCC_OPTIONS=3D'-v' '-mlittle-endian' '-mabi=3Dlp64' as -v -EL -mabi=3Dlp64 -o /tmp/ccTu98hj.o /tmp/ccetU9yt.s GNU assembler version 2.38 (aarch64-unknown-linux-gnu) using BFD version (G= NU Binutils) 2.38 COMPILER_PATH=3D/home/alarm/gcc-installation/usr/local/bin/../libexec/gcc/a= arch64-unknown-linux-gnu/13.0.1/:/home/alarm/gcc-installation/usr/local/bin= /../libexec/gcc/ LIBRARY_PATH=3D/home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch6= 4-unknown-linux-gnu/13.0.1/:/home/alarm/gcc-installation/usr/local/bin/../l= ib/gcc/:/home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch64-unkno= wn-linux-gnu/13.0.1/../../../../lib64/:/home/alarm/gcc-installation/usr/loc= al/bin/../lib/gcc/aarch64-unknown-linux-gnu/13.0.1/../../../:/lib/:/usr/lib/ COLLECT_GCC_OPTIONS=3D'-v' '-mlittle-endian' '-mabi=3Dlp64' '-dumpdir' 'a.' /home/alarm/gcc-installation/usr/local/bin/../libexec/gcc/aarch64-unknown-l= inux-gnu/13.0.1/collect2 -plugin /home/alarm/gcc-installation/usr/local/bin/../libexec/gcc/aarch64-unknown-l= inux-gnu/13.0.1/liblto_plugin.so -plugin-opt=3D/home/alarm/gcc-installation/usr/local/bin/../libexec/gcc/aar= ch64-unknown-linux-gnu/13.0.1/lto-wrapper -plugin-opt=3D-fresolution=3D/tmp/ccup8iGA.res -plugin-opt=3D-pass-through= =3D-lgcc -plugin-opt=3D-pass-through=3D-lgcc_s -plugin-opt=3D-pass-through=3D-lc -plugin-opt=3D-pass-through=3D-lgcc -plugin-opt=3D-pass-through=3D-lgcc_s --eh-frame-hdr -dynamic-linker /lib/ld-linux-aarch64.so.1 -X -EL -maarch64l= inux /lib/crt1.o /lib/crti.o /home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch64-unknown-linux= -gnu/13.0.1/crtbegin.o -L/home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch64-unknown-lin= ux-gnu/13.0.1 -L/home/alarm/gcc-installation/usr/local/bin/../lib/gcc -L/home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch64-unknown-lin= ux-gnu/13.0.1/../../../../lib64 -L/home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch64-unknown-lin= ux-gnu/13.0.1/../../.. /tmp/ccTu98hj.o -lgcc --push-state --as-needed -lgcc_s --pop-state -lc -lgcc --push-state --as-needed -lgcc_s --pop-state /home/alarm/gcc-installation/usr/local/bin/../lib/gcc/aarch64-unknown-linux= -gnu/13.0.1/crtend.o /lib/crtn.o COLLECT_GCC_OPTIONS=3D'-v' '-mlittle-endian' '-mabi=3Dlp64' '-dumpdir' 'a.' git bisect revealed this is a regression caused by commit 5edf02ed2b6de024f83a023d046a6a18f645bc83.=