Fixed a memory leak in the PDLToPDLInterp RootOrderingTest.

[sfuniak]

Summary

RootOrderingTest is a low-level unit test that creates values and uses them as vertices in a directed graph. These vertices were created using builder.create, but never freed, due to my insufficient understanding of the MLIR infrastructure.

[bondhugula]

mlir/unittests/Conversion/PDLToPDLInterp/RootOrderingTest.cpp

37–38

You need to be erasing those ops using erase().

38

As you know here that getDefiningOp() is a ConstantOp, please use a way to assert. For eg:

assert(v[i].getDefiningOp());
cast<ConstantOp>(v[i].getDefiningOp()).erase();

[bondhugula]

mlir/unittests/Conversion/PDLToPDLInterp/RootOrderingTest.cpp

37

Nit: unsigned here and below.

45

Please use ConstantIntOp -- that way, you can just pass i as the arg.

[sfuniak]

Review feedback.

[sfuniak]

Messed up a rebase, will submit a new diff.

[mehdi_amini]

mlir/unittests/Conversion/PDLToPDLInterp/RootOrderingTest.cpp

37

@bondhugula unsigned is an anti-pattern (unless working with bit-fields or other bit-manipulation), this has been widely documented I believe, both in C++ standardization paper (they are stuck with size_t in the standard library) and with conference talks like this one: https://www.youtube.com/watch?v=yG1OZ69H_-o

mlir/unittests/Conversion/PDLToPDLInterp/RootOrderingTest.cpp

 /// branching.
 class RootOrderingTest : public ::testing::Test {
 protected:
   RootOrderingTest() {
     context.loadDialect<StandardOpsDialect>();
     createValues();
   }
 
+  ~RootOrderingTest() {
+    for (int i = 0; i < 4; ++i)
+      v[i].getDefiningOp()->destroy();
+  }
+
   /// Creates the test values.
   void createValues() {
     OpBuilder builder(&context);
     for (int i = 0; i < 4; ++i)
       v[i] = builder.create<ConstantOp>(builder.getUnknownLoc(),
                                         builder.getI32IntegerAttr(i));
   }
 
   /// Checks that optimal branching on graph has the given cost and
   /// its preorder traversal results in the specified edges.
   void check(unsigned cost, OptimalBranching::EdgeList edges) {
     OptimalBranching opt(graph, v[0]);
     EXPECT_EQ(opt.solve(), cost);