[Error] Do not show warning when the offline cache path does not exist (

#5747)

* [Error] Do not show warning when the offline cache path does not exist

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

taichi/runtime/llvm/llvm_offline_cache.cpp

@@ -376,6 +376,9 @@ void LlvmOfflineCacheFileWriter::clean_cache(const std::string &path,
   {
     std::string lock_path = taichi::join_path(path, kMetadataFileLockName);
     if (!lock_with_file(lock_path)) {
+      if (!taichi::path_exists(path)) {
+        return;
+      }
       TI_WARN("Lock {} failed", lock_path);
       return;
     }

taichi/util/io.h

@@ -10,13 +10,19 @@
 #include <vector>
 #include <cstdio>
 #include <cstdlib>
+#include <sys/stat.h>
 
 #if defined(TI_PLATFORM_WINDOWS)
 #include <filesystem>
 #endif
 
 TI_NAMESPACE_BEGIN
 
+inline bool path_exists(const std::string &dir) {
+  struct stat buffer;
+  return stat(dir.c_str(), &buffer) == 0;
+}
+
 // TODO: move to std::filesystem after it's nonexperimental on all platforms
 inline void create_directories(const std::string &dir) {
 #if defined(TI_PLATFORM_WINDOWS)