https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109934
Bug ID: 109934
Summary: Wrong code at -O3 on x86_64-linux-gnu
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: shaohua.li at inf dot ethz.ch
Target Milestone: ---
For the following code, gcc trunk at -O3 emits wrong code.
Compiler explorer: https://godbolt.org/z/3E8xf69rP
$ cat a.c
int printf(const char *, ...);
short a;
long b = 3, c;
int d(int e) {
switch (e)
case 111:
case 222:
case 44:
return 0;
return e;
}
int main() {
for (; a >= 0; --a)
if (d(c + 23) - 23)
b = 0;
printf("%d\n", (int)b);
}
$
$ gcc-tk -O0 a.c && ./a.out
3
$ gcc-tk -O3 a.c && ./a.out
0
$
$ gcc-tk -v
Using built-in specs.
COLLECT_GCC=gcc-tk
COLLECT_LTO_WRAPPER=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-c09471fbc7588db2480f036aa56a2403d3c03ae5/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --disable-multilib --disable-bootstrap
--enable-languages=c,c++
--prefix=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-c09471fbc7588db2480f036aa56a2403d3c03ae5
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20230521 (experimental) (GCC)
$
