[MLIR][Presburger] skip IntegerPolyhedrons with LocalIds in coalesce

[webmiche]

Summary

This patch makes coalesce skip the comparison of all pairs of IntegerPolyhedrons with LocalIds rather than crash. The heuristics to handle these cases will be upstreamed later on.

[arjunp]

LGTM, please fix the nit:

mlir/lib/Analysis/Presburger/PresburgerSet.cpp

526–530

[webmiche]

Addressed comment.

mlir/lib/Analysis/Presburger/PresburgerSet.cpp

 /// `polyhedrons` left.
 static LogicalResult
 coalescePair(unsigned i, unsigned j,
              SmallVectorImpl<IntegerPolyhedron> &polyhedrons,
              SmallVectorImpl<Simplex> &simplices) {
 
   IntegerPolyhedron &a = polyhedrons[i];
   IntegerPolyhedron &b = polyhedrons[j];
-  assert(a.getNumLocalIds() == 0 && b.getNumLocalIds() == 0 &&
-         "Locals are not yet supported!");
+  /// Handling of local ids is not yet implemented, so these cases are skipped.
+  /// TODO: implement local id support.
+  if (a.getNumLocalIds() != 0 || b.getNumLocalIds() != 0)
+    return failure();
   Simplex &simpA = simplices[i];
   Simplex &simpB = simplices[j];
 
   SmallVector<ArrayRef<int64_t>, 2> redundantIneqsA;
   SmallVector<ArrayRef<int64_t>, 2> cuttingIneqsA;
   SmallVector<SmallVector<int64_t, 2>, 2> negEqs;
 
   // Organize all inequalities and equalities of `a` according to their type for
   // `b` into `redundantIneqsA` and `cuttingIneqsA` (and vice versa for all

mlir/unittests/Analysis/Presburger/PresburgerSetTest.cpp

PresburgerSet set = parsePresburgerSetFromPolyStrings(
              "(x) : (x == 0)",
              "(x) : (x - 2 == 0)",
              "(x) : (x + 2 == 0)",
              "(x) : (x - 2 >= 0, -x + 3 >= 0)",
          });
   expectCoalesce(3, set);
 }
 
+TEST(SetTest, coalesceDiv) {
+  PresburgerSet set =
+      parsePresburgerSetFromPolyStrings(1, {
+                                               "(x) : (x floordiv 2 == 0)",
+                                               "(x) : (x floordiv 2 - 1 == 0)",
+                                           });
+  expectCoalesce(2, set);
+}
+
+TEST(SetTest, coalesceDivOtherContained) {
+  PresburgerSet set =
+      parsePresburgerSetFromPolyStrings(1, {
+                                               "(x) : (x floordiv 2 == 0)",
+                                               "(x) : (x == 0)",
+                                               "(x) : (x >= 0, -x + 1 >= 0)",
+                                           });
+  expectCoalesce(2, set);
+}
+
 static void
 expectComputedVolumeIsValidOverapprox(const PresburgerSet &set,
                                       Optional<uint64_t> trueVolume,
                                       Optional<uint64_t> resultBound) {
   expectComputedVolumeIsValidOverapprox(set.computeVolume(), trueVolume,
                                         resultBound);
 }