Windows Filesystem fs::status Conditionally Call GetFileAttributes

[HaydnTrigg]

Rather than conditionally using the output from GetFileAttributesW move the branch to avoid calling GetFileAttributesW entirely if not required. This avoids hitting IO an extra time for a small performance improvement.

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[llvmbot]

@llvm/pr-subscribers-llvm-support

@llvm/pr-subscribers-platform-windows

Author: Haydn Trigg (HaydnTrigg)

Changes

Rather than conditionally using the output from GetFileAttributesW move the branch to avoid calling GetFileAttributesW entirely if not required. This avoids hitting IO an extra time for a small performance improvement.

---

Full diff: https://github.com/llvm/llvm-project/pull/78118.diff

1 Files Affected:

• (modified) llvm/lib/Support/Windows/Path.inc (+9-8)

diff --git a/llvm/lib/Support/Windows/Path.inc b/llvm/lib/Support/Windows/Path.inc
index 2bf68b7972e746..6598586545ddd0 100644
--- a/llvm/lib/Support/Windows/Path.inc
+++ b/llvm/lib/Support/Windows/Path.inc
@@ -777,14 +777,15 @@ std::error_code status(const Twine &path, file_status &result, bool Follow) {
   if (std::error_code ec = widenPath(path8, path_utf16))
     return ec;
 
-  DWORD attr = ::GetFileAttributesW(path_utf16.begin());
-  if (attr == INVALID_FILE_ATTRIBUTES)
-    return getStatus(INVALID_HANDLE_VALUE, result);
-
-  DWORD Flags = FILE_FLAG_BACKUP_SEMANTICS;
-  // Handle reparse points.
-  if (!Follow && (attr & FILE_ATTRIBUTE_REPARSE_POINT))
-    Flags |= FILE_FLAG_OPEN_REPARSE_POINT;
+  if (!Follow) {
+    DWORD attr = ::GetFileAttributesW(path_utf16.begin());
+    if (attr == INVALID_FILE_ATTRIBUTES)
+      return getStatus(INVALID_HANDLE_VALUE, result);
+    
+    // Handle reparse points.
+    if (attr & FILE_ATTRIBUTE_REPARSE_POINT)
+      Flags |= FILE_FLAG_OPEN_REPARSE_POINT;
+  }
 
   ScopedFileHandle h(
       ::CreateFileW(path_utf16.begin(), 0, // Attributes only.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[aganea]

LGTM

[tru]

Nice! Less calls to GetFileAttribtuesW is always a good thing!