[MLIR][Presburger] MultiAffineFunction:eliminateRedundantLocalId: fix bug where local offset was not considered

[arjunp]

Summary

Previously, when updating the outputs matrix, the local offset was not being considered.

[Groverkss]

LGTM.

mlir/lib/Analysis/Presburger/PWMAFunction.cpp

 void MultiAffineFunction::removeIdRange(IdKind kind, unsigned idStart,
                                         unsigned idLimit) {
   output.removeColumns(idStart + getIdKindOffset(kind), idLimit - idStart);
   IntegerPolyhedron::removeIdRange(kind, idStart, idLimit);
 }
 
 void MultiAffineFunction::eliminateRedundantLocalId(unsigned posA,
                                                     unsigned posB) {
-  output.addToColumn(posB, posA, /*scale=*/1);
+  unsigned localOffset = getIdKindOffset(IdKind::Local);
+  output.addToColumn(localOffset + posB, localOffset + posA, /*scale=*/1);
   IntegerPolyhedron::eliminateRedundantLocalId(posA, posB);
 }
 
 bool MultiAffineFunction::isEqualWhereDomainsOverlap(
     MultiAffineFunction other) const {
   if (!isSpaceCompatible(other))
     return false;
 

mlir/unittests/Analysis/Presburger/PWMAFunctionTest.cpp

TEST(PWMAFunction, valueAt) {
   EXPECT_FALSE(divPWMAF.valueAt({3, 3}).hasValue());
   EXPECT_FALSE(divPWMAF.valueAt({3, -3}).hasValue());
 
   EXPECT_THAT(*divPWMAF.valueAt({-2, 3}), ElementsAre(11, 23));
   EXPECT_FALSE(divPWMAF.valueAt({-2, -3}).hasValue());
 }
 
 TEST(PWMAFunction, removeIdRangeRegressionTest) {
-  PWMAFunction pwafA = parsePWMAF(
+  PWMAFunction pwmafA = parsePWMAF(
       /*numInputs=*/2, /*numOutputs=*/1,
       {
           {"(x, y) : (x == 0, y == 0, x - 2*(x floordiv 2) == 0, y - 2*(y "
            "floordiv 2) == 0)",
            {{0, 0, 0, 0, 0}}} // (0, 0)
       });
-  PWMAFunction pwafB = parsePWMAF(
+  PWMAFunction pwmafB = parsePWMAF(
       /*numInputs=*/2, /*numOutputs=*/1,
       {
           {"(x, y) : (x - 11*y == 0, 11*x - y == 0, x - 2*(x floordiv 2) == 0, "
            "y - 2*(y floordiv 2) == 0)",
            {{0, 0, 0, 0, 0}}} // (0, 0)
       });
-  EXPECT_TRUE(pwafA.isEqual(pwafB));
+  EXPECT_TRUE(pwmafA.isEqual(pwmafB));
+}
+
+TEST(PWMAFunction, eliminateRedundantLocalIdRegressionTest) {
+  PWMAFunction pwmafA = parsePWMAF(
+      /*numInputs=*/2, /*numOutputs=*/1,
+      {
+          {"(x, y) : (x - 2*(x floordiv 2) == 0, x - 2*y == 0)",
+           {{0, 1, 0, 0}}} // (0, 0)
+      });
+  PWMAFunction pwmafB = parsePWMAF(
+      /*numInputs=*/2, /*numOutputs=*/1,
+      {
+          {"(x, y) : (x - 2*(x floordiv 2) == 0, x - 2*y == 0)",
+           {{1, -1, 0, 0}}} // (0, 0)
+      });
+  EXPECT_TRUE(pwmafA.isEqual(pwmafB));
 }