Overview
The program test.cpp demonstrates an issue we have found when using the octagon domain of ELINA. test.cpp applies a sequence of affine transformation followed by meets with (>= 0) to an initial abstract domain (essentially fully connected layer + relu). We find test.cpp will have different behaviors if elina_lincons0_array_clear is not called in line 357 of test.cpp. If it is not called, then the second linear transformation yields bottom, but if it is then we get nonempty constraints. However, the weird part is that the constraints just before this transformation are the same regardless of whether we clear the array.
We show this by printing the linear constraints from the transformed domain, which we get from elina_abstract0_to_lincons_array. Each transformation should produce two sets of constraints: 1 for the transformation and 1 for the meet with constraint (>= 0). We have provided a script to verify that the constraints are the same. Usage instructions are below.
To our knowledge this occurs for all versions of ELINA but we know for sure it works up to the latest commit (0cbacc714a1fcc261df538c398cfa14d88a9251c)
Important Issue
In order to compile, we needed to add #include "gmp.h" on line 26 of opt_oct.h above the #ifdef __cplusplus.
Build test.cpp
g++ -std=c++11 test.cpp -lgmp -lmpfr -lelinaux -loptoct
Run test.cpp
$ ./a.out 1 > cleared.txt // clears constraints after meet with > 0$ ./a.out 0 > notCleared.txt // doesn't clear constraints after meetRun Comparison Script
$ python compareConstraints.py cleared.txt notCleared.txtThis script should output nothing if the constraints are the same.
Expected output
Without calling clear
19990: x94 - x99 + 0.067299343195221406067 >= 0
19991: -x95 - x99 + 0.067299343195221406067 >= 0
19992: x95 - x99 + 0.067299343195221406067 >= 0
19993: -x96 - x99 + 0.36762870847178780176 >= 0
19994: x96 - x99 + 0.067299343195221406067 >= 0
19995: -x97 - x99 + 0.22211343417206391715 >= 0
19996: x97 - x99 + 0.067299343195221406067 >= 0
19997: -x98 - x99 + 0.067299343195221406067 >= 0
19998: x98 - x99 + 0.067299343195221406067 >= 0
19999: -x99 + 0.067299343195221406067 >= 0
PRINTED AFTER RELU in Layer 0
opt_oct_assign_linexpr_array size: 100o->dim = 100, size = 100
opt_hmat_strong_closure returned positive
Layer: 1 before ReLU
0 disjuncts
Layer: 1 after ReLU
0 disjuncts
Layer: 2 before ReLU
0 disjuncts
Layer: 2 after ReLU
0 disjuncts
Clearing array
180: x9 + 9.3590256561560938309 >= 0
181: -x0 - x9 + 16.704760200984697605 >= 0
182: x0 - x9 + 16.459121417491466844 >= 0
183: -x1 - x9 + 18.609792410238117811 >= 0
184: x1 - x9 + 16.362381296435579259 >= 0
185: -x2 - x9 + 17.848708115739377434 >= 0
186: x2 - x9 + 18.298190135296426462 >= 0
187: -x3 - x9 + 18.050018503093863132 >= 0
188: x3 - x9 + 17.5431961445769673 >= 0
189: -x4 - x9 + 16.736410361856258078 >= 0
190: x4 - x9 + 20.169857810657251918 >= 0
191: -x5 - x9 + 17.99690804300194813 >= 0
192: x5 - x9 + 21.657778485156537585 >= 0
193: -x6 - x9 + 17.485219493301762839 >= 0
194: x6 - x9 + 19.676477711972690799 >= 0
195: -x7 - x9 + 15.160692565676692212 >= 0
196: x7 - x9 + 19.339093799103338256 >= 0
197: -x8 - x9 + 24.404344589898173013 >= 0
198: x8 - x9 + 10.142582519017700804 >= 0
199: -x9 + 8.2052457123764419578 >= 0
PRINTED AFTER RELU in Layer 2
Clearing