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//===- AffineStructuresTest.cpp - Tests for AffineStructures ----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "mlir/Analysis/AffineStructures.h"
#include <gmock/gmock.h>
#include <gtest/gtest.h>
#include <numeric>
namespace mlir {
/// Evaluate the value of the given affine expression at the specified point.
/// The expression is a list of coefficients for the dimensions followed by the
/// constant term.
int64_t valueAt(ArrayRef<int64_t> expr, ArrayRef<int64_t> point) {
assert(expr.size() == 1 + point.size());
int64_t value = expr.back();
for (unsigned i = 0; i < point.size(); ++i)
value += expr[i] * point[i];
return value;
}
/// If 'hasValue' is true, check that findIntegerSample returns a valid sample
/// for the FlatAffineConstraints fac.
///
/// If hasValue is false, check that findIntegerSample does not return None.
void checkSample(bool hasValue, const FlatAffineConstraints &fac) {
Optional<SmallVector<int64_t, 8>> maybeSample = fac.findIntegerSample();
if (!hasValue) {
EXPECT_FALSE(maybeSample.hasValue());
if (maybeSample.hasValue()) {
for (auto x : *maybeSample)
llvm::errs() << x << ' ';
llvm::errs() << '\n';
}
} else {
ASSERT_TRUE(maybeSample.hasValue());
for (unsigned i = 0; i < fac.getNumEqualities(); ++i)
EXPECT_EQ(valueAt(fac.getEquality(i), *maybeSample), 0);
for (unsigned i = 0; i < fac.getNumInequalities(); ++i)
EXPECT_GE(valueAt(fac.getInequality(i), *maybeSample), 0);
}
}
/// Construct a FlatAffineConstraints from a set of inequality and
/// equality constraints.
FlatAffineConstraints
makeFACFromConstraints(unsigned dims, ArrayRef<SmallVector<int64_t, 4>> ineqs,
ArrayRef<SmallVector<int64_t, 4>> eqs) {
FlatAffineConstraints fac(ineqs.size(), eqs.size(), dims + 1, dims);
for (const auto &eq : eqs)
fac.addEquality(eq);
for (const auto &ineq : ineqs)
fac.addInequality(ineq);
return fac;
}
/// Check sampling for all the permutations of the dimensions for the given
/// constraint set. Since the GBR algorithm progresses dimension-wise, different
/// orderings may cause the algorithm to proceed differently. At least some of
///.these permutations should make it past the heuristics and test the
/// implementation of the GBR algorithm itself.
void checkPermutationsSample(bool hasValue, unsigned nDim,
ArrayRef<SmallVector<int64_t, 4>> ineqs,
ArrayRef<SmallVector<int64_t, 4>> eqs) {
SmallVector<unsigned, 4> perm(nDim);
std::iota(perm.begin(), perm.end(), 0);
auto permute = [&perm](ArrayRef<int64_t> coeffs) {
SmallVector<int64_t, 4> permuted;
for (unsigned id : perm)
permuted.push_back(coeffs[id]);
permuted.push_back(coeffs.back());
return permuted;
};
do {
SmallVector<SmallVector<int64_t, 4>, 4> permutedIneqs, permutedEqs;
for (const auto &ineq : ineqs)
permutedIneqs.push_back(permute(ineq));
for (const auto &eq : eqs)
permutedEqs.push_back(permute(eq));
checkSample(hasValue,
makeFACFromConstraints(nDim, permutedIneqs, permutedEqs));
} while (std::next_permutation(perm.begin(), perm.end()));
}
TEST(FlatAffineConstraintsTest, FindSampleTest) {
// Bounded sets with only inequalities.
// 0 <= 7x <= 5
checkSample(true, makeFACFromConstraints(1, {{7, 0}, {-7, 5}}, {}));
// 1 <= 5x and 5x <= 4 (no solution).
checkSample(false, makeFACFromConstraints(1, {{5, -1}, {-5, 4}}, {}));
// 1 <= 5x and 5x <= 9 (solution: x = 1).
checkSample(true, makeFACFromConstraints(1, {{5, -1}, {-5, 9}}, {}));
// Bounded sets with equalities.
// x >= 8 and 40 >= y and x = y.
checkSample(
true, makeFACFromConstraints(2, {{1, 0, -8}, {0, -1, 40}}, {{1, -1, 0}}));
// x <= 10 and y <= 10 and 10 <= z and x + 2y = 3z.
// solution: x = y = z = 10.
checkSample(true, makeFACFromConstraints(
3, {{-1, 0, 0, 10}, {0, -1, 0, 10}, {0, 0, 1, -10}},
{{1, 2, -3, 0}}));
// x <= 10 and y <= 10 and 11 <= z and x + 2y = 3z.
// This implies x + 2y >= 33 and x + 2y <= 30, which has no solution.
checkSample(false, makeFACFromConstraints(
3, {{-1, 0, 0, 10}, {0, -1, 0, 10}, {0, 0, 1, -11}},
{{1, 2, -3, 0}}));
// 0 <= r and r <= 3 and 4q + r = 7.
// Solution: q = 1, r = 3.
checkSample(true,
makeFACFromConstraints(2, {{0, 1, 0}, {0, -1, 3}}, {{4, 1, -7}}));
// 4q + r = 7 and r = 0.
// Solution: q = 1, r = 3.
checkSample(false, makeFACFromConstraints(2, {}, {{4, 1, -7}, {0, 1, 0}}));
// The next two sets are large sets that should take a long time to sample
// with a naive branch and bound algorithm but can be sampled efficiently with
// the GBR algroithm.
//
// This is a triangle with vertices at (1/3, 0), (2/3, 0) and (10000, 10000).
checkSample(
true,
makeFACFromConstraints(
2, {{0, 1, 0}, {300000, -299999, -100000}, {-300000, 299998, 200000}},
{}));
// This is a tetrahedron with vertices at
// (1/3, 0, 0), (2/3, 0, 0), (2/3, 0, 10000), and (10000, 10000, 10000).
// The first three points form a triangular base on the xz plane with the
// apex at the fourth point, which is the only integer point.
checkPermutationsSample(
true, 3,
{
{0, 1, 0, 0}, // y >= 0
{0, -1, 1, 0}, // z >= y
{300000, -299998, -1,
-100000}, // -300000x + 299998y + 100000 + z <= 0.
{-150000, 149999, 0, 100000}, // -150000x + 149999y + 100000 >= 0.
},
{});
// Same thing with some spurious extra dimensions equated to constants.
checkSample(true,
makeFACFromConstraints(
5,
{
{0, 1, 0, 1, -1, 0},
{0, -1, 1, -1, 1, 0},
{300000, -299998, -1, -9, 21, -112000},
{-150000, 149999, 0, -15, 47, 68000},
},
{{0, 0, 0, 1, -1, 0}, // p = q.
{0, 0, 0, 1, 1, -2000}})); // p + q = 20000 => p = q = 10000.
// This is a tetrahedron with vertices at
// (1/3, 0, 0), (2/3, 0, 0), (2/3, 0, 100), (100, 100 - 1/3, 100).
checkPermutationsSample(false, 3,
{
{0, 1, 0, 0},
{0, -300, 299, 0},
{300 * 299, -89400, -299, -100 * 299},
{-897, 894, 0, 598},
},
{});
// Two tests involving equalities that are integer empty but not rational
// empty.
// This is a line segment from (0, 1/3) to (100, 100 + 1/3).
checkSample(false, makeFACFromConstraints(
2,
{
{1, 0, 0}, // x >= 0.
{-1, 0, 100} // -x + 100 >= 0, i.e., x <= 100.
},
{
{3, -3, 1} // 3x - 3y + 1 = 0, i.e., y = x + 1/3.
}));
// A thin parallelogram. 0 <= x <= 100 and x + 1/3 <= y <= x + 2/3.
checkSample(false, makeFACFromConstraints(2,
{
{1, 0, 0}, // x >= 0.
{-1, 0, 100}, // x <= 100.
{3, -3, 2}, // 3x - 3y >= -2.
{-3, 3, -1}, // 3x - 3y <= -1.
},
{}));
checkSample(true, makeFACFromConstraints(2,
{
{2, 0, 0}, // 2x >= 1.
{-2, 0, 99}, // 2x <= 99.
{0, 2, 0}, // 2y >= 0.
{0, -2, 99}, // 2y <= 99.
},
{}));
}
TEST(FlatAffineConstraintsTest, IsIntegerEmptyTest) {
// 1 <= 5x and 5x <= 4 (no solution).
EXPECT_TRUE(
makeFACFromConstraints(1, {{5, -1}, {-5, 4}}, {}).isIntegerEmpty());
// 1 <= 5x and 5x <= 9 (solution: x = 1).
EXPECT_FALSE(
makeFACFromConstraints(1, {{5, -1}, {-5, 9}}, {}).isIntegerEmpty());
// An unbounded set, which isIntegerEmpty should detect as unbounded and
// return without calling findIntegerSample.
EXPECT_FALSE(makeFACFromConstraints(3,
{
{2, 0, 0, -1},
{-2, 0, 0, 1},
{0, 2, 0, -1},
{0, -2, 0, 1},
{0, 0, 2, -1},
},
{})
.isIntegerEmpty());
// FlatAffineConstraints::isEmpty() does not detect the following sets to be
// empty.
// 3x + 7y = 1 and 0 <= x, y <= 10.
// Since x and y are non-negative, 3x + 7y can never be 1.
EXPECT_TRUE(
makeFACFromConstraints(
2, {{1, 0, 0}, {-1, 0, 10}, {0, 1, 0}, {0, -1, 10}}, {{3, 7, -1}})
.isIntegerEmpty());
// 2x = 3y and y = x - 1 and x + y = 6z + 2 and 0 <= x, y <= 100.
// Substituting y = x - 1 in 3y = 2x, we obtain x = 3 and hence y = 2.
// Since x + y = 5 cannot be equal to 6z + 2 for any z, the set is empty.
EXPECT_TRUE(
makeFACFromConstraints(3,
{
{1, 0, 0, 0},
{-1, 0, 0, 100},
{0, 1, 0, 0},
{0, -1, 0, 100},
},
{{2, -3, 0, 0}, {1, -1, 0, -1}, {1, 1, -6, -2}})
.isIntegerEmpty());
// 2x = 3y and y = x - 1 + 6z and x + y = 6q + 2 and 0 <= x, y <= 100.
// 2x = 3y implies x is a multiple of 3 and y is even.
// Now y = x - 1 + 6z implies y = 2 mod 3. In fact, since y is even, we have
// y = 2 mod 6. Then since x = y + 1 + 6z, we have x = 3 mod 6, implying
// x + y = 5 mod 6, which contradicts x + y = 6q + 2, so the set is empty.
EXPECT_TRUE(makeFACFromConstraints(
4,
{
{1, 0, 0, 0, 0},
{-1, 0, 0, 0, 100},
{0, 1, 0, 0, 0},
{0, -1, 0, 0, 100},
},
{{2, -3, 0, 0, 0}, {1, -1, 6, 0, -1}, {1, 1, 0, -6, -2}})
.isIntegerEmpty());
}
} // namespace mlir
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