From 605c4608d94da06a4a5225e461da30f47adf2d9f Mon Sep 17 00:00:00 2001
From: LibretroAdmin <reallibretroretroarch@gmail.com>
Date: Mon, 1 Aug 2022 22:14:26 +0200
Subject: [PATCH] Optimize fill_pathname_join - avoid the call to
 fill_pathname_slash() which would have an implicit strlen cost

---
 libretro-common/file/file_path.c         | 18 ++++++++++++++++--
 libretro-common/include/file/file_path.h |  4 ++--
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/libretro-common/file/file_path.c b/libretro-common/file/file_path.c
index 0b2f953788..fef13b5a39 100644
--- a/libretro-common/file/file_path.c
+++ b/libretro-common/file/file_path.c
@@ -910,11 +910,25 @@ void fill_pathname_resolve_relative(char *out_path,
 size_t fill_pathname_join(char *out_path,
       const char *dir, const char *path, size_t size)
 {
+   size_t len = 0;
    if (out_path != dir)
-      strlcpy(out_path, dir, size);
+      len = strlcpy(out_path, dir, size);
 
    if (*out_path)
-      fill_pathname_slash(out_path, size);
+   {
+      const char *last_slash = find_last_slash(out_path);
+      if (last_slash)
+      {
+         /* Try to preserve slash type. */
+         if (last_slash != (out_path + len - 1))
+         {
+            out_path[len]   = last_slash[0];
+            out_path[len+1] = '\0';
+         }
+      }
+      else
+         strlcat(out_path, PATH_DEFAULT_SLASH(), size);
+   }
 
    return strlcat(out_path, path, size);
 }
diff --git a/libretro-common/include/file/file_path.h b/libretro-common/include/file/file_path.h
index 17ca9ded3c..8613e8c9ff 100644
--- a/libretro-common/include/file/file_path.h
+++ b/libretro-common/include/file/file_path.h
@@ -446,12 +446,12 @@ void fill_pathname_resolve_relative(char *out_path, const char *in_refpath,
  * @size               : size of output path
  *
  * Joins a directory (@dir) and path (@path) together.
- * Makes sure not to get  two consecutive slashes
+ * Makes sure not to get two consecutive slashes
  * between directory and path.
  * 
  * Hidden non-leaf function cost: 
  * - calls strlcpy
- * - calls fill_pathname_slash()
+ * - calls find_last_slash()
  * - calls strlcat
  **/
 size_t fill_pathname_join(char *out_path, const char *dir,