mlir/Presburger: reinstate use of LogicalResult (#97415)

Follow up on a desire post-landing d0fee98 (mlir/Presburger: strip
dependency on MLIRSupport) to reinstate the use of LogicalResult in
Presburger. Since db791b2 (mlir/LogicalResult: move into llvm),
LogicalResult is in LLVM, and fulfilling this desire is possible while
still maintaining the goal of stripping the Presburger library of mlir
dependencies.

Author: artagnon

mlir/include/mlir/Analysis/Presburger/IntegerRelation.h

@@ -21,13 +21,17 @@
 #include "mlir/Analysis/Presburger/Utils.h"
 #include "llvm/ADT/DynamicAPInt.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/LogicalResult.h"
 #include <optional>
 
 namespace mlir {
 namespace presburger {
 using llvm::DynamicAPInt;
+using llvm::failure;
 using llvm::int64fromDynamicAPInt;
+using llvm::LogicalResult;
 using llvm::SmallVectorImpl;
+using llvm::success;
 
 class IntegerRelation;
 class IntegerPolyhedron;
@@ -478,7 +482,7 @@ class IntegerRelation {
   /// equality detection; if successful, the constant is substituted for the
   /// variable everywhere in the constraint system and then removed from the
   /// system.
-  bool constantFoldVar(unsigned pos);
+  LogicalResult constantFoldVar(unsigned pos);
 
   /// This method calls `constantFoldVar` for the specified range of variables,
   /// `num` variables starting at position `pos`.
@@ -501,7 +505,7 @@ class IntegerRelation {
   /// 3) this   = {0 <= d0 <= 5, 1 <= d1 <= 9}
   ///    other  = {2 <= d0 <= 6, 5 <= d1 <= 15},
   ///    output = {0 <= d0 <= 6, 1 <= d1 <= 15}
-  bool unionBoundingBox(const IntegerRelation &other);
+  LogicalResult unionBoundingBox(const IntegerRelation &other);
 
   /// Returns the smallest known constant bound for the extent of the specified
   /// variable (pos^th), i.e., the smallest known constant that is greater
@@ -774,8 +778,8 @@ class IntegerRelation {
   /// Eliminates a single variable at `position` from equality and inequality
   /// constraints. Returns `success` if the variable was eliminated, and
   /// `failure` otherwise.
-  inline bool gaussianEliminateVar(unsigned position) {
-    return gaussianEliminateVars(position, position + 1) == 1;
+  inline LogicalResult gaussianEliminateVar(unsigned position) {
+    return success(gaussianEliminateVars(position, position + 1) == 1);
   }
 
   /// Removes local variables using equalities. Each equality is checked if it

mlir/include/mlir/Analysis/Presburger/Simplex.h

@@ -445,7 +445,7 @@ class LexSimplexBase : public SimplexBase {
   /// lexicopositivity of the basis transform. The row must have a non-positive
   /// sample value. If this is not possible, return failure. This occurs when
   /// the constraints have no solution or the sample value is zero.
-  bool moveRowUnknownToColumn(unsigned row);
+  LogicalResult moveRowUnknownToColumn(unsigned row);
 
   /// Given a row that has a non-integer sample value, add an inequality to cut
   /// away this fractional sample value from the polytope without removing any
@@ -459,7 +459,7 @@ class LexSimplexBase : public SimplexBase {
   ///
   /// Return failure if the tableau became empty, and success if it didn't.
   /// Failure status indicates that the polytope was integer empty.
-  bool addCut(unsigned row);
+  LogicalResult addCut(unsigned row);
 
   /// Undo the addition of the last constraint. This is only called while
   /// rolling back.
@@ -511,7 +511,7 @@ class LexSimplex : public LexSimplexBase {
   MaybeOptimum<SmallVector<Fraction, 8>> getRationalSample() const;
 
   /// Make the tableau configuration consistent.
-  bool restoreRationalConsistency();
+  LogicalResult restoreRationalConsistency();
 
   /// Return whether the specified row is violated;
   bool rowIsViolated(unsigned row) const;
@@ -626,7 +626,7 @@ class SymbolicLexSimplex : public LexSimplexBase {
   /// Return failure if the tableau became empty, indicating that the polytope
   /// is always integer empty in the current symbol domain.
   /// Return success otherwise.
-  bool doNonBranchingPivots();
+  LogicalResult doNonBranchingPivots();
 
   /// Get a row that is always violated in the current domain, if one exists.
   std::optional<unsigned> maybeGetAlwaysViolatedRow();
@@ -647,7 +647,7 @@ class SymbolicLexSimplex : public LexSimplexBase {
   /// at the time of the call. (This function may modify the symbol domain, but
   /// failure statu indicates that the polytope was empty for all symbol values
   /// in the initial domain.)
-  bool addSymbolicCut(unsigned row);
+  LogicalResult addSymbolicCut(unsigned row);
 
   /// Get the numerator of the symbolic sample of the specific row.
   /// This is an affine expression in the symbols with integer coefficients.
@@ -820,7 +820,7 @@ class Simplex : public SimplexBase {
   ///
   /// Returns success if the unknown was successfully restored to a non-negative
   /// sample value, failure otherwise.
-  bool restoreRow(Unknown &u);
+  LogicalResult restoreRow(Unknown &u);
 
   /// Find a pivot to change the sample value of row in the specified
   /// direction while preserving tableau consistency, except that if the

mlir/lib/Analysis/FlatLinearValueConstraints.cpp

@@ -1247,10 +1247,10 @@ LogicalResult FlatLinearValueConstraints::unionBoundingBox(
   if (!areVarsAligned(*this, otherCst)) {
     FlatLinearValueConstraints otherCopy(otherCst);
     mergeAndAlignVars(/*offset=*/getNumDimVars(), this, &otherCopy);
-    return success(IntegerPolyhedron::unionBoundingBox(otherCopy));
+    return IntegerPolyhedron::unionBoundingBox(otherCopy);
   }
 
-  return success(IntegerPolyhedron::unionBoundingBox(otherCst));
+  return IntegerPolyhedron::unionBoundingBox(otherCst);
 }
 
 //===----------------------------------------------------------------------===//

mlir/lib/Analysis/Presburger/IntegerRelation.cpp

@@ -26,6 +26,7 @@
 #include "llvm/ADT/Sequence.h"
 #include "llvm/ADT/SmallBitVector.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/LogicalResult.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cassert>
@@ -1552,22 +1553,22 @@ static int findEqualityToConstant(const IntegerRelation &cst, unsigned pos,
   return -1;
 }
 
-bool IntegerRelation::constantFoldVar(unsigned pos) {
+LogicalResult IntegerRelation::constantFoldVar(unsigned pos) {
   assert(pos < getNumVars() && "invalid position");
   int rowIdx;
   if ((rowIdx = findEqualityToConstant(*this, pos)) == -1)
-    return false;
+    return failure();
 
   // atEq(rowIdx, pos) is either -1 or 1.
   assert(atEq(rowIdx, pos) * atEq(rowIdx, pos) == 1);
   DynamicAPInt constVal = -atEq(rowIdx, getNumCols() - 1) / atEq(rowIdx, pos);
   setAndEliminate(pos, constVal);
-  return true;
+  return success();
 }
 
 void IntegerRelation::constantFoldVarRange(unsigned pos, unsigned num) {
   for (unsigned s = pos, t = pos, e = pos + num; s < e; s++) {
-    if (!constantFoldVar(t))
+    if (constantFoldVar(t).failed())
       t++;
   }
 }
@@ -1944,9 +1945,9 @@ void IntegerRelation::fourierMotzkinEliminate(unsigned pos, bool darkShadow,
   for (unsigned r = 0, e = getNumEqualities(); r < e; r++) {
     if (atEq(r, pos) != 0) {
       // Use Gaussian elimination here (since we have an equality).
-      bool ret = gaussianEliminateVar(pos);
+      LogicalResult ret = gaussianEliminateVar(pos);
       (void)ret;
-      assert(ret && "Gaussian elimination guaranteed to succeed");
+      assert(ret.succeeded() && "Gaussian elimination guaranteed to succeed");
       LLVM_DEBUG(llvm::dbgs() << "FM output (through Gaussian elimination):\n");
       LLVM_DEBUG(dump());
       return;
@@ -2173,7 +2174,8 @@ static void getCommonConstraints(const IntegerRelation &a,
 
 // Computes the bounding box with respect to 'other' by finding the min of the
 // lower bounds and the max of the upper bounds along each of the dimensions.
-bool IntegerRelation::unionBoundingBox(const IntegerRelation &otherCst) {
+LogicalResult
+IntegerRelation::unionBoundingBox(const IntegerRelation &otherCst) {
   assert(space.isEqual(otherCst.getSpace()) && "Spaces should match.");
   assert(getNumLocalVars() == 0 && "local ids not supported yet here");
 
@@ -2201,13 +2203,13 @@ bool IntegerRelation::unionBoundingBox(const IntegerRelation &otherCst) {
     if (!extent.has_value())
       // TODO: symbolic extents when necessary.
       // TODO: handle union if a dimension is unbounded.
-      return false;
+      return failure();
 
     auto otherExtent = otherCst.getConstantBoundOnDimSize(
         d, &otherLb, &otherLbFloorDivisor, &otherUb);
     if (!otherExtent.has_value() || lbFloorDivisor != otherLbFloorDivisor)
       // TODO: symbolic extents when necessary.
-      return false;
+      return failure();
 
     assert(lbFloorDivisor > 0 && "divisor always expected to be positive");
 
@@ -2227,7 +2229,7 @@ bool IntegerRelation::unionBoundingBox(const IntegerRelation &otherCst) {
       auto constLb = getConstantBound(BoundType::LB, d);
       auto constOtherLb = otherCst.getConstantBound(BoundType::LB, d);
       if (!constLb.has_value() || !constOtherLb.has_value())
-        return false;
+        return failure();
       std::fill(minLb.begin(), minLb.end(), 0);
       minLb.back() = std::min(*constLb, *constOtherLb);
     }
@@ -2243,7 +2245,7 @@ bool IntegerRelation::unionBoundingBox(const IntegerRelation &otherCst) {
       auto constUb = getConstantBound(BoundType::UB, d);
       auto constOtherUb = otherCst.getConstantBound(BoundType::UB, d);
       if (!constUb.has_value() || !constOtherUb.has_value())
-        return false;
+        return failure();
       std::fill(maxUb.begin(), maxUb.end(), 0);
       maxUb.back() = std::max(*constUb, *constOtherUb);
     }
@@ -2281,7 +2283,7 @@ bool IntegerRelation::unionBoundingBox(const IntegerRelation &otherCst) {
   // union (since the above are just the union along dimensions); we shouldn't
   // be discarding any other constraints on the symbols.
 
-  return true;
+  return success();
 }
 
 bool IntegerRelation::isColZero(unsigned pos) const {

mlir/lib/Analysis/Presburger/PresburgerRelation.cpp

@@ -15,6 +15,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallBitVector.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/LogicalResult.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <functional>
@@ -753,18 +754,18 @@ class presburger::SetCoalescer {
   ///     \___\|/            \_____/
   ///
   ///
-  bool coalescePairCutCase(unsigned i, unsigned j);
+  LogicalResult coalescePairCutCase(unsigned i, unsigned j);
 
   /// Types the inequality `ineq` according to its `IneqType` for `simp` into
   /// `redundantIneqsB` and `cuttingIneqsB`. Returns success, if no separate
   /// inequalities were encountered. Otherwise, returns failure.
-  bool typeInequality(ArrayRef<DynamicAPInt> ineq, Simplex &simp);
+  LogicalResult typeInequality(ArrayRef<DynamicAPInt> ineq, Simplex &simp);
 
   /// Types the equality `eq`, i.e. for `eq` == 0, types both `eq` >= 0 and
   /// -`eq` >= 0 according to their `IneqType` for `simp` into
   /// `redundantIneqsB` and `cuttingIneqsB`. Returns success, if no separate
   /// inequalities were encountered. Otherwise, returns failure.
-  bool typeEquality(ArrayRef<DynamicAPInt> eq, Simplex &simp);
+  LogicalResult typeEquality(ArrayRef<DynamicAPInt> eq, Simplex &simp);
 
   /// Replaces the element at position `i` with the last element and erases
   /// the last element for both `disjuncts` and `simplices`.
@@ -775,7 +776,7 @@ class presburger::SetCoalescer {
   /// successfully coalesced. The simplices in `simplices` need to be the ones
   /// constructed from `disjuncts`. At this point, there are no empty
   /// disjuncts in `disjuncts` left.
-  bool coalescePair(unsigned i, unsigned j);
+  LogicalResult coalescePair(unsigned i, unsigned j);
 };
 
 /// Constructs a `SetCoalescer` from a `PresburgerRelation`. Only adds non-empty
@@ -818,7 +819,7 @@ PresburgerRelation SetCoalescer::coalesce() {
       cuttingIneqsB.clear();
       if (i == j)
         continue;
-      if (coalescePair(i, j)) {
+      if (coalescePair(i, j).succeeded()) {
         broken = true;
         break;
       }
@@ -902,15 +903,15 @@ void SetCoalescer::addCoalescedDisjunct(unsigned i, unsigned j,
 ///     \___\|/            \_____/
 ///
 ///
-bool SetCoalescer::coalescePairCutCase(unsigned i, unsigned j) {
+LogicalResult SetCoalescer::coalescePairCutCase(unsigned i, unsigned j) {
   /// All inequalities of `b` need to be redundant. We already know that the
   /// redundant ones are, so only the cutting ones remain to be checked.
   Simplex &simp = simplices[i];
   IntegerRelation &disjunct = disjuncts[i];
   if (llvm::any_of(cuttingIneqsA, [this, &simp](ArrayRef<DynamicAPInt> curr) {
         return !isFacetContained(curr, simp);
       }))
-    return false;
+    return failure();
   IntegerRelation newSet(disjunct.getSpace());
 
   for (ArrayRef<DynamicAPInt> curr : redundantIneqsA)
@@ -920,23 +921,25 @@ bool SetCoalescer::coalescePairCutCase(unsigned i, unsigned j) {
     newSet.addInequality(curr);
 
   addCoalescedDisjunct(i, j, newSet);
-  return true;
+  return success();
 }
 
-bool SetCoalescer::typeInequality(ArrayRef<DynamicAPInt> ineq, Simplex &simp) {
+LogicalResult SetCoalescer::typeInequality(ArrayRef<DynamicAPInt> ineq,
+                                           Simplex &simp) {
   Simplex::IneqType type = simp.findIneqType(ineq);
   if (type == Simplex::IneqType::Redundant)
     redundantIneqsB.push_back(ineq);
   else if (type == Simplex::IneqType::Cut)
     cuttingIneqsB.push_back(ineq);
   else
-    return false;
-  return true;
+    return failure();
+  return success();
 }
 
-bool SetCoalescer::typeEquality(ArrayRef<DynamicAPInt> eq, Simplex &simp) {
-  if (!typeInequality(eq, simp))
-    return false;
+LogicalResult SetCoalescer::typeEquality(ArrayRef<DynamicAPInt> eq,
+                                         Simplex &simp) {
+  if (typeInequality(eq, simp).failed())
+    return failure();
   negEqs.push_back(getNegatedCoeffs(eq));
   ArrayRef<DynamicAPInt> inv(negEqs.back());
   return typeInequality(inv, simp);
@@ -951,15 +954,15 @@ void SetCoalescer::eraseDisjunct(unsigned i) {
   simplices.pop_back();
 }
 
-bool SetCoalescer::coalescePair(unsigned i, unsigned j) {
+LogicalResult SetCoalescer::coalescePair(unsigned i, unsigned j) {
 
   IntegerRelation &a = disjuncts[i];
   IntegerRelation &b = disjuncts[j];
   /// Handling of local ids is not yet implemented, so these cases are
   /// skipped.
   /// TODO: implement local id support.
   if (a.getNumLocalVars() != 0 || b.getNumLocalVars() != 0)
-    return false;
+    return failure();
   Simplex &simpA = simplices[i];
   Simplex &simpB = simplices[j];
 
@@ -969,34 +972,34 @@ bool SetCoalescer::coalescePair(unsigned i, unsigned j) {
   // inequality is encountered during typing, the two IntegerRelations
   // cannot be coalesced.
   for (int k = 0, e = a.getNumInequalities(); k < e; ++k)
-    if (!typeInequality(a.getInequality(k), simpB))
-      return false;
+    if (typeInequality(a.getInequality(k), simpB).failed())
+      return failure();
 
   for (int k = 0, e = a.getNumEqualities(); k < e; ++k)
-    if (!typeEquality(a.getEquality(k), simpB))
-      return false;
+    if (typeEquality(a.getEquality(k), simpB).failed())
+      return failure();
 
   std::swap(redundantIneqsA, redundantIneqsB);
   std::swap(cuttingIneqsA, cuttingIneqsB);
 
   for (int k = 0, e = b.getNumInequalities(); k < e; ++k)
-    if (!typeInequality(b.getInequality(k), simpA))
-      return false;
+    if (typeInequality(b.getInequality(k), simpA).failed())
+      return failure();
 
   for (int k = 0, e = b.getNumEqualities(); k < e; ++k)
-    if (!typeEquality(b.getEquality(k), simpA))
-      return false;
+    if (typeEquality(b.getEquality(k), simpA).failed())
+      return failure();
 
   // If there are no cutting inequalities of `a`, `b` is contained
   // within `a`.
   if (cuttingIneqsA.empty()) {
     eraseDisjunct(j);
-    return true;
+    return success();
   }
 
   // Try to apply the cut case
-  if (coalescePairCutCase(i, j))
-    return true;
+  if (coalescePairCutCase(i, j).succeeded())
+    return success();
 
   // Swap the vectors to compare the pair (j,i) instead of (i,j).
   std::swap(redundantIneqsA, redundantIneqsB);
@@ -1006,7 +1009,7 @@ bool SetCoalescer::coalescePair(unsigned i, unsigned j) {
   // within `a`.
   if (cuttingIneqsA.empty()) {
     eraseDisjunct(i);
-    return true;
+    return success();
   }
 
   // Try to apply the cut case