[TIR]Fix the crash of the pass RemoveNoOp (apache#13808)

Fix the crash of the pass RemoveNoOp.

Co-authored-by: lightzhan-intellif <zhan.liang@intellif.com>

src/tir/transforms/remove_no_op.cc

@@ -119,6 +119,11 @@ class NoOpRemover : public arith::IRMutatorWithAnalyzer {
   Stmt VisitStmt_(const IfThenElseNode* op) final {
     Stmt stmt = Parent::VisitStmt_(op);
     op = stmt.as<IfThenElseNode>();
+    // Sometimes the condition can be statically determined,
+    // in which the type of the `stmt` will not be IfThenElseNode.
+    if (!op) {
+      return stmt;
+    }
     if (op->else_case) {
       bool no_op_else = is_no_op(op->else_case.value());
       bool no_op_then = is_no_op(op->then_case);

tests/python/unittest/test_tir_transform_remove_no_op.py

@@ -603,5 +603,19 @@ def expected(A: T.Buffer[16, "int32"], C: T.Buffer[1, "int32"]):
             C[0] = C[0] + B[i]
 
 
+class TestCertainConditon(BaseBeforeAfter):
+    """The conditon of the If-Else node is certain.
+    This would cause `Segmentation fault` error before."""
+
+    def before():
+        if True:
+            T.evaluate(0)
+        else:
+            T.evaluate(0)
+
+    def expected():
+        T.evaluate(0)
+
+
 if __name__ == "__main__":
     tvm.testing.main()