https://bugs.llvm.org/show_bug.cgi?id=45631
Bug ID: 45631
Summary: clang produces wrong code with -O1 to -Os
Product: clang
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: C
Assignee: unassignedclangb...@nondot.org
Reporter: haoxi...@gmail.com
CC: blitzrak...@gmail.com, dgre...@apple.com,
erik.pilking...@gmail.com, llvm-bugs@lists.llvm.org,
richard-l...@metafoo.co.uk
Hi, test.c
#include<stdio.h>
long a;
int b = 94, tf_0_var_795;
void c(long long *d, int e) { *d = e; }
int main() {
tf_0_var_795 = !(~0 + 7 << b);
c(&a, tf_0_var_795);
printf("%d\n", a);
}
Clang produces wrong code with -O1 to -Os, the correct output is 0, but it gets
wrong with 1.
$ clang-trunk -w test.c && ./a.out
0
$ clang-trunk -w -O1 test.c && ./a.out
1
$ clang-trunk -w -O2 test.c && ./a.out
1
$ clang-trunk -w -O3 test.c && ./a.out
1
$ clang-trunk -w -Os test.c && ./a.out
1
Also, I have tested almost all released clang versions I used, the results are
the same as I reported above.
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