[MLIR][Presburger] getDivRepr: fix bug where dividend was negated

Also updated the tests, which were asserting the wrong behaviour. Reviewed By: Groverkss Differential Revision: https://reviews.llvm.org/D128735

Author: Superty

mlir/lib/Analysis/Presburger/Utils.cpp

@@ -172,9 +172,9 @@ static LogicalResult getDivRepr(const IntegerRelation &cst, unsigned pos,
  expr.resize(cst.getNumCols(), 0);
  for (unsigned i = 0, e = cst.getNumIds(); i < e; ++i)
  if (i != pos)
- expr[i] = signDiv * cst.atEq(eqInd, i);
+ expr[i] = -signDiv * cst.atEq(eqInd, i);
 
- expr.back() = signDiv * cst.atEq(eqInd, cst.getNumCols() - 1);
+ expr.back() = -signDiv * cst.atEq(eqInd, cst.getNumCols() - 1);
  normalizeDivisionByGCD(expr, divisor);
 
  return success();

mlir/unittests/Analysis/Presburger/IntegerPolyhedronTest.cpp

@@ -725,7 +725,7 @@ TEST(IntegerPolyhedronTest, computeLocalReprFromEquality) {
  // Convert `q` to a local variable.
  poly.convertToLocal(IdKind::SetDim, 2, 3);
 
- std::vector<SmallVector<int64_t, 8>> divisions = {{-1, -1, 0, 0}};
+ std::vector<SmallVector<int64_t, 8>> divisions = {{1, 1, 0, 0}};
  SmallVector<unsigned, 8> denoms = {4};
 
  checkDivisionRepresentation(poly, divisions, denoms);
@@ -735,7 +735,7 @@ TEST(IntegerPolyhedronTest, computeLocalReprFromEquality) {
  // Convert `q` to a local variable.
  poly.convertToLocal(IdKind::SetDim, 2, 3);
 
- std::vector<SmallVector<int64_t, 8>> divisions = {{-1, -1, 0, 0}};
+ std::vector<SmallVector<int64_t, 8>> divisions = {{1, 1, 0, 0}};
  SmallVector<unsigned, 8> denoms = {4};
 
  checkDivisionRepresentation(poly, divisions, denoms);
@@ -745,7 +745,7 @@ TEST(IntegerPolyhedronTest, computeLocalReprFromEquality) {
  // Convert `q` to a local variable.
  poly.convertToLocal(IdKind::SetDim, 2, 3);
 
- std::vector<SmallVector<int64_t, 8>> divisions = {{1, 1, 0, -2}};
+ std::vector<SmallVector<int64_t, 8>> divisions = {{-1, -1, 0, 2}};
  SmallVector<unsigned, 8> denoms = {3};
 
  checkDivisionRepresentation(poly, divisions, denoms);
@@ -761,7 +761,7 @@ TEST(IntegerPolyhedronTest, computeLocalReprFromEqualityAndInequality) {
  poly.convertToLocal(IdKind::SetDim, 2, 4);
 
  std::vector<SmallVector<int64_t, 8>> divisions = {{1, 1, 0, 0, 1},
- {-1, -1, 0, 0, 0}};
+ {1, 1, 0, 0, 0}};
  SmallVector<unsigned, 8> denoms = {4, 3};
 
  checkDivisionRepresentation(poly, divisions, denoms);