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/* Testcase from Threader's distribution. For details see:
http://www.model.in.tum.de/~popeea/research/threader
This file is adapted from the example introduced in the paper:
Thread-Modular Verification for Shared-Memory Programs
by Cormac Flanagan, Stephen Freund, Shaz Qadeer.
*/
int w=0, r=0, x, y;
void __VERIFIER_atomic_take_write_lock() {
__VERIFIER_assume(w==0 && r==0);
w = 1;
}
void __VERIFIER_atomic_take_read_lock() {
__VERIFIER_assume(w==0);
r = r+1;
}
void __VERIFIER_atomic_release_read_lock() {
r = r-1;
}
void *writer() { //writer
__VERIFIER_atomic_take_write_lock();
x = 3;
w = 0;
}
void *reader() { //reader
int l;
__VERIFIER_atomic_take_read_lock();
l = x;
y = l;
assert(y == x);
__VERIFIER_atomic_release_read_lock();
}
int main() {
__CPROVER_ASYNC_1: writer();
__CPROVER_ASYNC_1: reader();
__CPROVER_ASYNC_1: writer();
__CPROVER_ASYNC_1: reader();
return 0;
}
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