[Mlir-commits] [mlir] [mlir][test] Add unittests for `getInversePermutation` (PR #116945)

[Javed Absar]

================
@@ -76,3 +76,39 @@ TEST(AffineMapTest, isProjectedPermutation) {
   AffineMap map10 = AffineMap::get(6, 0, {d5, d3, d2, d4}, &ctx);
   EXPECT_TRUE(map10.isProjectedPermutation());
 }
+
+TEST(AffineMapTest, getInversePermutation) {
+  MLIRContext ctx;
+  OpBuilder b(&ctx);
+
+  // 0. Empty map
+  AffineMap map0 = AffineMap::get(0, 0, {}, &ctx);
+  AffineMap inverseMap0 = inversePermutation(map0);
+  EXPECT_TRUE(inverseMap0.isEmpty());
+
+  auto d0 = b.getAffineDimExpr(0);
+  auto d1 = b.getAffineDimExpr(1);
+  auto d2 = b.getAffineDimExpr(2);
+
+  // 1.   (d0, d1, d2) -> (d1, d1, d0, d2, d1, d2, d1, d0)
+  AffineMap map1 = AffineMap::get(3, 0, {d1, d1, d0, d2, d1, d2, d1, d0}, &ctx);
+  //      (d0, d1, d2, d3, d4, d5, d6, d7) -> (d2, d0, d3)
+  AffineMap inverseMap1 = inversePermutation(map1);
+  auto resultsInv1 = inverseMap1.getResults();
+  EXPECT_EQ(resultsInv1.size(), 3UL);
+  EXPECT_TRUE(resultsInv1[0].isFunctionOfDim(2));
----------------
javedabsar1 wrote:

Please double check this instead of fully trusting me. But I think in case of `isFunctionOfDim`, `2` has to appear somewhere in the expression e.g. `d2+d1`, and so is a less restrictive ask then if we are really check `d2` and only `d2. 
```
  auto expr = llvm::dyn_cast<AffineDimExpr>(resultsInv1[0]);
   if (!expr)  EXPECT_EQ(0,1);
  EXPECT_EQ(expr.getPosition(), 2)
```

https://github.com/llvm/llvm-project/pull/116945