[mlir][bytecode] Avoid crash when test dialect version is missing

Author: Men-cotton

mlir/test/Bytecode/roundtrip-missing-dialect.mlir

@@ -0,0 +1,6 @@
+// RUN: mlir-opt %s --test-bytecode-roundtrip=test-dialect-version=2.0 | FileCheck %s
+
+// CHECK-LABEL: func.func @main
+func.func @main() {
+  return
+}

mlir/test/lib/IR/TestBytecodeRoundtrip.cpp

@@ -141,8 +141,8 @@ struct TestBytecodeRoundtripPass
             DialectBytecodeWriter &writer) -> LogicalResult {
           // Do not override anything if version greater than 2.0.
           auto versionOr = writer.getDialectVersion<test::TestDialect>();
-          assert(succeeded(versionOr) && "expected reader to be able to access "
-                                         "the version for test dialect");
+          if (failed(versionOr))
+            return failure();
           const auto *version =
               reinterpret_cast<const test::TestDialectVersion *>(*versionOr);
           if (version->major_ >= 2)
@@ -166,8 +166,8 @@ struct TestBytecodeRoundtripPass
             Type &entry) -> LogicalResult {
           // Get test dialect version from the version map.
           auto versionOr = reader.getDialectVersion<test::TestDialect>();
-          assert(succeeded(versionOr) && "expected reader to be able to access "
-                                         "the version for test dialect");
+          if (failed(versionOr))
+            return success();
           const auto *version =
               reinterpret_cast<const test::TestDialectVersion *>(*versionOr);
           if (version->major_ >= 2)