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Check if events may alias when deriving RA knowledge from witnesses (… #766

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Merged
merged 3 commits into from
Nov 4, 2024
Merged

Check if events may alias when deriving RA knowledge from witnesses (… #766

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667a2bf
Check if events may alias when deriving RA knowledge from witnesses (…
hernan-poncedeleon Nov 2, 2024
8dcd206
Add FIXME
hernan-poncedeleon Nov 3, 2024
d4c015a
Disable XRA for SVCOMP
hernan-poncedeleon Nov 3, 2024
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14 changes: 11 additions & 3 deletions dartagnan/src/main/java/com/dat3m/dartagnan/witness/graphml/WitnessGraph.java
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Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,11 @@ public BooleanFormula encode(EncodingContext context) {
return bmgr.and(enc);
}

// FIXME: the code to generate RA knowledge from a violation witness is extremely fragile.
// We should rewrite this code to extract knowledge about the hb relation (from which the
// witness was actually generated) rather than rf and co. Then, the extended relation
// analysis should propagate this knowledge top-down to reach the base relations.

private boolean graphEdgeImpliesHbEdge() {
return hasAttributed(PRODUCER.toString()) && getAttributed(PRODUCER.toString()).equals("Dartagnan");
}
Expand All @@ -150,8 +155,10 @@ public EventGraph getReadFromKnowledge(Program program, AliasAnalysis alias) {
// If a graph edge implies a hb-relation, inter-thread communication guarantees
// same address and thus rf.
if (last instanceof Store && current instanceof Load
&& ((graphEdgeImpliesHbEdge() && !last.getThread().equals(current.getThread()))
|| alias.mustAlias(last, current))) {
&& ((graphEdgeImpliesHbEdge()
&& !last.getThread().equals(current.getThread())
&& alias.mayAlias(last, current))
|| alias.mustAlias(last, current))) {
k.add(last, current);
}
last = current;
Expand All @@ -175,7 +182,8 @@ public EventGraph getCoherenceKnowledge(Program program, AliasAnalysis alias) {
.forEach(w2 -> k.add(w1, w2));
// Special case for cross-thread edges.
final Store immSucc = writes.get(i+1);
if(graphEdgeImpliesHbEdge() && !w1.getThread().equals(immSucc.getThread())) {
if(graphEdgeImpliesHbEdge() && !w1.getThread().equals(immSucc.getThread())
&& alias.mayAlias(w1, immSucc)) {
k.add(w1, immSucc);
}
}
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2 changes: 2 additions & 0 deletions svcomp.properties
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Expand Up @@ -3,3 +3,5 @@ encoding.integers=true
svcomp.step=5
svcomp.umax=27
witness=graphml
// We can get rid of the option below once #767 is fixed
wmm.analysis.extendedRelationAnalysis=false
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