From 7e26271a01fa807742a5dfc8ae07a87d7b304801 Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Wed, 22 Oct 2025 09:13:00 +0900
Subject: [PATCH] mruby-string-ext: hoist RSTRING_PTR calls in String#tr

Optimizes String#tr by hoisting RSTRING_PTR calls for pattern strings
outside the main loop to avoid repeated conditional checks.

Before: 2 RSTRING_PTR calls per iteration (once for each pattern)
After: 2 RSTRING_PTR calls total (pointers cached outside loop)

String#tr is commonly used for character transliteration and this
optimization provides measurable improvement for long strings.

Co-authored-by: Claude <noreply@anthropic.com>
---
 mrbgems/mruby-string-ext/src/string.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/mrbgems/mruby-string-ext/src/string.c b/mrbgems/mruby-string-ext/src/string.c
index fa22d397d..b0b90add2 100644
--- a/mrbgems/mruby-string-ext/src/string.c
+++ b/mrbgems/mruby-string-ext/src/string.c
@@ -521,14 +521,17 @@ str_tr(mrb_state *mrb, mrb_value str, mrb_value p1, mrb_value p2, mrb_bool squee
   char *s = RSTRING_PTR(str);
   mrb_int len = RSTRING_LEN(str);
 
+  /* Hoist pointer retrieval outside loop to avoid repeated conditionals */
+  const char *p1_ptr = RSTRING_PTR(p1);
+  const char *p2_ptr = RSTRING_PTR(p2);
   mrb_int i, j;
   for (i=j=0; i<len; i++,j++) {
-    mrb_int n = tr_find_character(&pat, RSTRING_PTR(p1), s[i]);
+    mrb_int n = tr_find_character(&pat, p1_ptr, s[i]);
 
     if (i>j) s[j] = s[i];
     if (n >= 0) {
       flag_changed = TRUE;
-      mrb_int c = tr_get_character(&rep, RSTRING_PTR(p2), n);
+      mrb_int c = tr_get_character(&rep, p2_ptr, n);
 
       if (c < 0 || (squeeze && c == lastch)) {
         j--;