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ConstraintAnalysis: Do not add something already known to be true when ANDing #8889

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Merged
kripken merged 1 commit into from
Jul 8, 2026
+19 −1
Merged

ConstraintAnalysis: Do not add something already known to be true when ANDing #8889

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8 changes: 7 additions & 1 deletion src/ir/constraint.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -134,7 +134,13 @@ void AndedConstraintSet::approximateAnd(const Constraint& c) {
return;
}

if (proves(c) == False) {
auto result = proves(c);
if (result == True) {
// We already prove c to be true, so it adds nothing.
// TODO: we could also see if c proves us true, and replace things we
// already have with c when possible
return;
} else if (result == False) {
// We are now a contradiction.
isContradiction = true;
return;
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12 changes: 12 additions & 0 deletions test/gtest/constraint.cpp
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Expand Up @@ -207,5 +207,17 @@ TEST(ConstraintTest, TestMaxCapacity) {
EXPECT_EQ(s.proves(not40), Unknown);
}

TEST(ConstraintTest, TestDeduplication) {
Constraint eq10{Eq, {Literal(int32_t(10))}};

AndedConstraintSet s;
EXPECT_EQ(s.size(), 0);
s.set(eq10);
EXPECT_EQ(s.size(), 1);
// The size does not increase when we add eq10 again.
s.approximateAnd(eq10);
EXPECT_EQ(s.size(), 1);
}

// TODO: test an approximateOr of { x = 10 } and { x >= 0 }, once we support
// inequalities
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