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ConstraintAnalysis: Add missing unsigned cases #8963

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12 changes: 12 additions & 0 deletions src/ir/constraint.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -265,11 +265,17 @@ std::optional<Constraint> approximateOrTermEqualPair(const Abstract::Op aOp,
if (aOp == Eq && bOp == GtS) {
return Constraint{GeS, term};
}
if (aOp == Eq && bOp == GtU) {
return Constraint{GeU, term};
}

// x > C || x >= C === x >= C
if (aOp == GtS && bOp == GeS) {
return Constraint{GeS, term};
}
if (aOp == GtU && bOp == GeU) {
return Constraint{GeU, term};
}

// TODO: all the rest

Expand All @@ -286,11 +292,17 @@ std::optional<Constraint> approximateOrAdjacentConstantPair(
if (aOp == Eq && bOp == GeS && !aConstant.isSignedMax()) {
return Constraint{GeS, {aConstant}};
}
if (aOp == Eq && bOp == GeU && !aConstant.isUnsignedMax()) {
return Constraint{GeU, {aConstant}};
}

// x > C || x >= C+1 === x > C, if C+1 does not overflow.
if (aOp == GtS && bOp == GeS && !aConstant.isSignedMax()) {
return Constraint{GtS, {aConstant}};
}
if (aOp == GtU && bOp == GeU && !aConstant.isUnsignedMax()) {
return Constraint{GtU, {aConstant}};
}

// TODO: all the rest

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65 changes: 63 additions & 2 deletions test/gtest/constraint.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -348,10 +348,12 @@ TEST(ConstraintTest, TestOrLoop) {
checkOr(leftNe, right, empty);

// Change the GtS on the right to GtU:
// { x == 5 } || { x >U 5 && x <= 42 } ==> { x <= 42 }
// { x == 5 } || { x >U 5 && x <= 42 } ==> { x >=U 5 && x <= 42 }
AndedConstraintSet rightGtU(
{{GtU, {Literal(int32_t(5))}}, {LeS, {Literal(int32_t(42))}}});
checkOr(left, rightGtU, rightOnly42);
AndedConstraintSet resultMixed(
{{GeU, {Literal(int32_t(5))}}, {LeS, {Literal(int32_t(42))}}});
checkOr(left, rightGtU, resultMixed);

// Change the LeS on the right to LeU:
// { x == 5 } || { x > 5 && x <=U 42 } ==> { x >= 5 && x <=U 42 }
Expand All @@ -373,6 +375,65 @@ TEST(ConstraintTest, TestOrLoop) {
checkOr(left, rightAdded, resultAdded);
}

TEST(ConstraintTest, TestOrLoopUnsigned) {
// As above, but unsigned.

// { x == 5 } || { x > 5 && x <= 42 } ==> { x >= 5 && x <= 42 }
AndedConstraintSet left{{Eq, {Literal(int32_t(5))}}};
AndedConstraintSet right(
{{GtU, {Literal(int32_t(5))}}, {LeU, {Literal(int32_t(42))}}});
AndedConstraintSet result(
{{GeU, {Literal(int32_t(5))}}, {LeU, {Literal(int32_t(42))}}});
checkOr(left, right, result);

// Changes to constants:

// Change 5 on the left to 7:
// { x == 7 } || { x > 5 && x <= 42 } ==> { x > 5 && x <= 42}
AndedConstraintSet left7{{Eq, {Literal(int32_t(7))}}};
checkOr(left7, right, right);

// Change 5 on the left to 99:
// { x == 99 } || { x > 5 && x <= 42 } ==> { x > 5 }
// TODO: we could emit a range (5, 99]
AndedConstraintSet left99{{Eq, {Literal(int32_t(99))}}};
AndedConstraintSet rightOnly5{{GtU, {Literal(int32_t(5))}}};
checkOr(left99, right, rightOnly5);

// Change 5 on the left to 4:
// { x == 4 } || { x > 5 && x <= 42 } ==> { x <= 42 }
// TODO: we could emit a range [4, 42]
AndedConstraintSet left4{{Eq, {Literal(int32_t(4))}}};
AndedConstraintSet rightOnly42({{LeU, {Literal(int32_t(42))}}});
checkOr(left4, right, rightOnly42);

// Change 5 on the right to 6:
// { x == 5 } || { x > 6 && x <= 42 } ==> { x <= 42 }
AndedConstraintSet right6(
{{GtU, {Literal(int32_t(6))}}, {LeU, {Literal(int32_t(42))}}});
checkOr(left, right6, rightOnly42);

// Changes to operations:

// Change the Eq on the left to Ne. We fail to find anything for the OR.
// { x != 5 } || { x > 5 && x <= 42 } ==> {}
// TODO: we could emit x != 5
AndedConstraintSet leftNe{{Ne, {Literal(int32_t(5))}}};
auto empty = AndedConstraintSet::makeProvesNothing();
checkOr(leftNe, right, empty);

// Add an operation on the right, x != 21:
// { x == 5 } || { x > 5 && x <= 42 && x != 21 } ==>
// { x >= 5 && x <= 42 && x != 21 }
AndedConstraintSet rightAdded({{GtU, {Literal(int32_t(5))}},
{LeU, {Literal(int32_t(42))}},
{Ne, {Literal(int32_t(21))}}});
AndedConstraintSet resultAdded({{GeU, {Literal(int32_t(5))}},
{LeU, {Literal(int32_t(42))}},
{Ne, {Literal(int32_t(21))}}});
checkOr(left, rightAdded, resultAdded);
}

static void checkAnd(const AndedConstraintSet& a,
const AndedConstraintSet& b,
const AndedConstraintSet& result) {
Expand Down
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