message: Log Hlo IR during AOT compilation
diff: @@ -757,8 +757,14 @@ CpuCompiler::CompileAheadOfTime(std::vector<std::unique_ptr<HloModule>> modules,
  HloModule* module = modules[i].get();
  VLOG(1) << "Compiling ahead-of-time: " << module->name();
  + VLOG(2) << "Before optimization:";
  + XLA_VLOG_LINES(2, module->ToString());
  +
  TF_RETURN_IF_ERROR(RunHloPasses(module, /*is_aot_compile=*/true));
  + VLOG(2) << "After optimization:";
  + XLA_VLOG_LINES(2, module->ToString());
  +
  TF_ASSIGN_OR_RETURN(
  SequentialHloOrdering::HloModuleSequence module_sequence,
  CreateMemoryMinimizingSequence(*module, BufferSizeBytesFunction()));
  