http://llvm.org/bugs/show_bug.cgi?id=17623
Bug ID: 17623
Summary: possible wrong code with volatile and lto
Product: tools
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: lto
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
Playing with csmith I came across several possible wrong code bugs with lto.
Two examples:
1)
markus@x4 clang_bugs % cat test_lto_crash.i
int a, b, e;
int *c;
int **volatile d = &c;
int main() {
for (; a <= 0; a++) {
e = 0;
*d = &e;
if (*c)
return 0;
}
return 0;
}
markus@x4 clang_bugs % clang -O0 -flto test_lto_crash.i && ./a.out
markus@x4 clang_bugs % clang -O2 -flto test_lto_crash.i && ./a.out
[1] 29647 segmentation fault ./a.out
markus@x4 clang_bugs % clang -O2 test_lto_crash.i && ./a.out
markus@x4 clang_bugs % gcc -O2 -flto test_lto_crash.i && ./a.out
markus@x4 clang_bugs %
2)
markus@x4 clang_bugs % cat test_lto_wrong.i
int a, b;
int *volatile c = &b;
int main() {
a = 1;
for (; a; a--) {
*c = 1;
b |= 4;
}
printf("%d\n", b);
return 0;
}
markus@x4 clang_bugs % clang -w -O2 test_lto_wrong.i && ./a.out
5
markus@x4 clang_bugs % clang -w -O0 -flto test_lto_wrong.i && ./a.out
5
markus@x4 clang_bugs % gcc -w -O2 -flto test_lto_wrong.i && ./a.out
5
markus@x4 clang_bugs % clang -w -O2 -flto test_lto_wrong.i && ./a.out
4
markus@x4 clang_bugs %
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