[MLIR][Presburger] normalizeDivisionByGCD: fix bug when constant term…

… is negative Reviewed By: Groverkss Differential Revision: https://reviews.llvm.org/D119531
yushiqie · Feb 11, 2022 · 855cd84 · 855cd84
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commit 855cd84
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diff --git a/mlir/lib/Analysis/Presburger/Utils.cpp b/mlir/lib/Analysis/Presburger/Utils.cpp
@@ -45,7 +45,7 @@ static void normalizeDivisionByGCD(SmallVectorImpl<int64_t> &dividend,
 
   // Normalize the dividend and the denominator.
   std::transform(dividend.begin(), dividend.end(), dividend.begin(),
-                 [gcd](int64_t &n) { return floor((double)(n / gcd)); });
+                 [gcd](int64_t &n) { return floorDiv(n, gcd); });
   divisor /= gcd;
 }
 

diff --git a/mlir/unittests/Analysis/Presburger/IntegerPolyhedronTest.cpp b/mlir/unittests/Analysis/Presburger/IntegerPolyhedronTest.cpp
@@ -794,6 +794,21 @@ TEST(IntegerPolyhedronTest, computeLocalReprNoRepr) {
   checkDivisionRepresentation(poly, divisions, denoms);
 }
 
+TEST(IntegerPolyhedronTest, computeLocalReprNegConstNormalize) {
+  MLIRContext context;
+  IntegerPolyhedron poly = parsePoly(
+      "(x, q) : (-1 - 3*x - 6 * q >= 0, 6 + 3*x + 6*q >= 0)", &context);
+  // Convert q to a local variable.
+  poly.convertDimToLocal(1, 2);
+
+  // q = floor((-1/3 - x)/2)
+  //   = floor((1/3) + (-1 - x)/2)
+  //   = floor((-1 - x)/2).
+  std::vector<SmallVector<int64_t, 8>> divisions = {{-1, 0, -1}};
+  SmallVector<unsigned, 8> denoms = {2};
+  checkDivisionRepresentation(poly, divisions, denoms);
+}
+
 TEST(IntegerPolyhedronTest, simplifyLocalsTest) {
   // (x) : (exists y: 2x + y = 1 and y = 2).
   IntegerPolyhedron poly(1, 0, 1);