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From: "jwzeng at nuaa dot edu.cn" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/110475] New: [14 Regression] Wrong code at -O2/3/s on x86_64-pc-linux-gnu Date: Thu, 29 Jun 2023 06:36:53 +0000 [thread overview] Message-ID: <bug-110475-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110475 Bug ID: 110475 Summary: [14 Regression] Wrong code at -O2/3/s on x86_64-pc-linux-gnu Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: jwzeng at nuaa dot edu.cn Target Milestone: --- Link to the Compiler Explorer: https://godbolt.org/z/qTn1MErqh The following code snippet: #include <stdio.h> unsigned long long int res = 0; unsigned int a = 4042837206U; int b = 1558001202; #define min(a, b) ((a) < (b) ? (a) : (b)) int main() { res = (unsigned long long int) min(1, b ? a : 1558001202); printf("%llu\n", res); return 0; } > $ /usr/gcc-trunk/bin/gcc -O0 bug.c; ./a.out > 1 > $ /usr/gcc-trunk/bin/gcc -O1 bug.c; ./a.out > 1 > $ /usr/gcc-trunk/bin/gcc -O2 bug.c; ./a.out > 4042837207 > $ /usr/gcc-trunk/bin/gcc -O3 bug.c; ./a.out > 4042837207 > $ /usr/gcc-trunk/bin/gcc -Os bug.c; ./a.out > 4042837207 When compiled with -O2/3/s, it prints the wrong result 4042837207 instead of 1. Earlier GCCs do not have this bug. The following statement is in the code snippet above: > res = (unsigned long long int) min(1, b ? a : 1558001202); When the last number 1558001202 of this statement is changed to 0 or 1, it will also output the wrong result 4042837207 under the optimization of -O1. Changing to other numbers that are not 0 or 1 will not make this program output wrong results at -O1. > $ /usr/gcc-trunk/bin/gcc --version Using built-in specs. COLLECT_GCC=/home/compilers/gcc/gcc-trunk/bin/gcc COLLECT_LTO_WRAPPER=/home/compilers/gcc/gcc-trunk/bin/../libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../gcc-trunk-source/gcc/configure --enable-languages=c,c++,fortran --enable-checking=release --enable-valgrind-annotations --disable-werror --disable-libstdcxx-pch --enable-libgomp --enable-lto --enable-gold --with-plugin-ld=gold --prefix=/usr/local/gcc-trunk Thread model: posix Supported LTO compression algorithms: zlib gcc version 14.0.0 20230619 (experimental) [master r14-1917-gf8e0270272] (GCC)
next reply other threads:[~2023-06-29 6:36 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-29 6:36 jwzeng at nuaa dot edu.cn [this message] 2023-06-29 7:29 ` [Bug tree-optimization/110475] " pinskia at gcc dot gnu.org 2023-06-29 7:33 ` rguenth at gcc dot gnu.org 2023-06-29 15:42 ` pinskia at gcc dot gnu.org
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