From 47502c55b0ce2e4cd3f43fefb77d9c2c11ed7c0a Mon Sep 17 00:00:00 2001
From: =?utf8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Fri, 3 Nov 2023 16:02:56 +0100
Subject: [PATCH] ; Reorder struct Lisp_Hash_Table and struct hash_table_test

Mainly for efficiency, to keep frequently used fields together.
---
 src/fns.c  | 12 ++++++------
 src/lisp.h | 35 +++++++++++++++++------------------
 2 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/src/fns.c b/src/fns.c
index e491202cf54..3e650b13c1f 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -4493,12 +4493,12 @@ hashfn_user_defined (Lisp_Object key, struct Lisp_Hash_Table *h)
 }
 
 struct hash_table_test const
-  hashtest_eq = { LISPSYM_INITIALLY (Qeq), LISPSYM_INITIALLY (Qnil),
-		  LISPSYM_INITIALLY (Qnil), 0, hashfn_eq },
-  hashtest_eql = { LISPSYM_INITIALLY (Qeql), LISPSYM_INITIALLY (Qnil),
-		   LISPSYM_INITIALLY (Qnil), cmpfn_eql, hashfn_eql },
-  hashtest_equal = { LISPSYM_INITIALLY (Qequal), LISPSYM_INITIALLY (Qnil),
-		     LISPSYM_INITIALLY (Qnil), cmpfn_equal, hashfn_equal };
+  hashtest_eq = { .name = LISPSYM_INITIALLY (Qeq),
+		  .cmpfn = 0, .hashfn = hashfn_eq },
+  hashtest_eql = { .name = LISPSYM_INITIALLY (Qeql),
+		   .cmpfn = cmpfn_eql, .hashfn = hashfn_eql },
+  hashtest_equal = { .name = LISPSYM_INITIALLY (Qequal),
+		     .cmpfn = cmpfn_equal, .hashfn = hashfn_equal };
 
 /* Allocate basically initialized hash table.  */
 
diff --git a/src/lisp.h b/src/lisp.h
index b11237381d9..658bcd8b780 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2397,9 +2397,11 @@ typedef enum {
 
 struct hash_table_test
 {
-  /* FIXME: reorder for efficiency */
-  /* Function used to compare keys; always a bare symbol.  */
-  Lisp_Object name;
+  /* C function to compute hash code.  */
+  hash_hash_t (*hashfn) (Lisp_Object, struct Lisp_Hash_Table *);
+
+  /* C function to compare two keys.  */
+  Lisp_Object (*cmpfn) (Lisp_Object, Lisp_Object, struct Lisp_Hash_Table *);
 
   /* User-supplied hash function, or nil.  */
   Lisp_Object user_hash_function;
@@ -2407,11 +2409,8 @@ struct hash_table_test
   /* User-supplied key comparison function, or nil.  */
   Lisp_Object user_cmp_function;
 
-  /* C function to compare two keys.  */
-  Lisp_Object (*cmpfn) (Lisp_Object, Lisp_Object, struct Lisp_Hash_Table *);
-
-  /* C function to compute hash code.  */
-  hash_hash_t (*hashfn) (Lisp_Object, struct Lisp_Hash_Table *);
+  /* Function used to compare keys; always a bare symbol.  */
+  Lisp_Object name;
 };
 
 typedef enum {
@@ -2480,6 +2479,16 @@ struct Lisp_Hash_Table
      This vector is table_size entries long.  */
   hash_hash_t *hash;
 
+  /* Vector of keys and values.  The key of item I is found at index
+     2 * I, the value is found at index 2 * I + 1.
+     If the key is HASH_UNUSED_ENTRY_KEY, then this slot is unused.
+     This is gc_marked specially if the table is weak.
+     This vector is 2 * table_size entries long.  */
+  Lisp_Object *key_and_value;
+
+  /* The comparison and hash functions.  */
+  const struct hash_table_test *test;
+
   /* Vector used to chain entries.  If entry I is free, next[I] is the
      entry number of the next free item.  If entry I is non-free,
      next[I] is the index of the next entry in the collision chain,
@@ -2508,16 +2517,6 @@ struct Lisp_Hash_Table
      immutable for recursive attempts to mutate it.  */
   bool mutable;
 
-  /* Vector of keys and values.  The key of item I is found at index
-     2 * I, the value is found at index 2 * I + 1.
-     If the key is HASH_UNUSED_ENTRY_KEY, then this slot is unused.
-     This is gc_marked specially if the table is weak.
-     This vector is 2 * table_size entries long.  */
-  Lisp_Object *key_and_value;
-
-  /* The comparison and hash functions.  */
-  const struct hash_table_test *test;
-
   /* Next weak hash table if this is a weak hash table.  The head of
      the list is in weak_hash_tables.  Used only during garbage
      collection --- at other times, it is NULL.  */
-- 
2.39.2