From bd872a3f2e0cdb52fb3201997ddc19a84b52bf3e Mon Sep 17 00:00:00 2001
From: Tanner Gooding <tagoo@outlook.com>
Date: Sun, 12 Jul 2026 15:21:04 -0700
Subject: [PATCH] Cache normalized file names to avoid re-allocating them per
 cursor

IsIncludedFileOrLocation runs for every cursor and re-derives the file's
normalized name from scratch each time -- file.Name.ToString().NormalizePath(),
plus a NormalizeFullPath() (Path.GetFullPath) on the traversal-name path. The
same file recurs for every cursor it contains, so this repeats the same work
thousands of times.

Cache the normalized name and full name per CXFile, mirroring the existing
_fileContents cache (same key type, cleared per translation unit in
GenerateBindings). On the TerraFX Windows SDK d3d12 generation this drops
sampled allocations from 179.6 MB to 142.7 MB (~20%), eliminating the 18.0 MB
of NormalizePath and 8.7 MB of NormalizeFullPath entirely.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
---
 .../PInvokeGenerator.Predicates.cs                | 15 ++++++++++++---
 .../PInvokeGenerator.cs                           |  3 +++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.Predicates.cs b/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.Predicates.cs
index 7270c301..a73796ef 100644
--- a/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.Predicates.cs
+++ b/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.Predicates.cs
@@ -310,8 +310,17 @@ bool IsIncludedFileOrLocation(Cursor cursor, CXFile file, CXSourceLocation locat
             // Use case insensitive comparison on Windows
             var equalityComparer = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? StringComparer.OrdinalIgnoreCase : StringComparer.Ordinal;
 
-            // Normalize paths to be '/' for comparison
-            var fileName = file.Name.ToString().NormalizePath();
+            // Normalize paths to be '/' for comparison. The same file recurs for
+            // every cursor it contains, so cache the normalized names per file to
+            // avoid re-allocating them (and re-running Path.GetFullPath) each call.
+            if (!_fileNames.TryGetValue(file, out var names))
+            {
+                var name = file.Name.ToString().NormalizePath();
+                names = (name, name.NormalizeFullPath());
+                _fileNames.Add(file, names);
+            }
+
+            var fileName = names.Name;
 
             if (_visitedFiles.Add(fileName) && _config.LogVisitedFiles)
             {
@@ -322,7 +331,7 @@ bool IsIncludedFileOrLocation(Cursor cursor, CXFile file, CXSourceLocation locat
             {
                 return true;
             }
-            else if (_config.TraversalNames.Contains(fileName.NormalizeFullPath(), equalityComparer))
+            else if (_config.TraversalNames.Contains(names.FullName, equalityComparer))
             {
                 return true;
             }
diff --git a/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.cs b/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.cs
index 87bc0e58..08bdcb7d 100644
--- a/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.cs
+++ b/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.cs
@@ -63,6 +63,7 @@ public sealed partial class PInvokeGenerator : IDisposable
     private readonly Dictionary<string, HashSet<string>> _topLevelClassUsings;
     private readonly Dictionary<string, List<string>> _topLevelClassAttributes;
     private readonly Dictionary<CXFile, (nuint Address, nuint Length)> _fileContents;
+    private readonly Dictionary<CXFile, (string Name, string FullName)> _fileNames;
     private readonly HashSet<string> _topLevelClassNames;
     private readonly HashSet<string> _usedRemappings;
     private readonly string _placeholderMacroType;
@@ -161,6 +162,7 @@ public PInvokeGenerator(PInvokeGeneratorConfiguration config, Func<string, Strea
             _topLevelClassNames = new HashSet<string>(StringComparer.Ordinal);
             _topLevelClassAttributes = new Dictionary<string, List<string>>(StringComparer.Ordinal);
             _fileContents = [];
+            _fileNames = [];
             _topLevelClassUsings = new Dictionary<string, HashSet<string>>(StringComparer.Ordinal);
             _usedRemappings = new HashSet<string>(StringComparer.Ordinal);
             _filePath = "";
@@ -1680,6 +1682,7 @@ public void GenerateBindings(TranslationUnit translationUnit, string filePath, s
         _overloadIndices.Clear();
         _isExcluded.Clear();
         _fileContents.Clear();
+        _fileNames.Clear();
 
         if (translationUnit.Handle.NumDiagnostics != 0)
         {