Commit: patch 9.2.1044: Vim script execution is slower than necessary

[Christian Brabandt]

patch 9.2.1044: Vim script execution is slower than necessary

Commit: https://github.com/vim/vim/commit/a74c5751211f31334d38dbb9f62062e2ffe76a32
Author: Julien Voisin <julien...@dustri.org>
Date: Mon Sep 7 20:46:47 2026 +0000

patch 9.2.1044: Vim script execution is slower than necessary

Problem: in_vim9script() is called very frequently on the script
evaluation hot path, but is a cross-file function call whose
overhead dominates its trivial body.
Solution: Make in_vim9script() a "static inline" function in vim.h so it
is inlined at its call sites.

in_vim9script() only reads two globals, yet it accounted for about 9% of self
time in a legacy script evaluation profile because it is invoked in a lot of
call sites in the eval path and could not be inlined across translation units.
Moving the body to a `static inline` function in vim.h guarded with `#ifndef
PROTO` and removing the out-of-line definition eliminates the call overhead.
Measured with retired instructions, this reduces legacy Vim script execution by
roughly 3 to 4% in tight loops, function calls, builtin-heavy and string
processing workloads; expression-bound editing such as `:s//\=expr/g` improves
by about 2%. Vim9 script is unaffected. All in all, nothing groundbreaking, but
a couple of percents improvements for a simple `static inline` sounds
worthwhile to me.

closes: #21215

Signed-off-by: Julien Voisin <julien...@dustri.org>
Signed-off-by: Christian Brabandt <c...@256bit.org>

diff --git a/src/proto/vim9script.pro b/src/proto/vim9script.pro
index 160825554..c75cc0c78 100644
--- a/src/proto/vim9script.pro
+++ b/src/proto/vim9script.pro
@@ -1,5 +1,4 @@
/* vim9script.c */
-int in_vim9script(void);
int in_old_script(int max_version);
int current_script_is_vim9(void);
void clear_vim9_scriptlocal_vars(int sid);
diff --git a/src/version.c b/src/version.c
index b884a80f3..de23cc0a7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@ static char *(features[]) =

static int included_patches[] =
{ /* Add new patch number below this line */
+/**/
+ 1044,
/**/
1043,
/**/
diff --git a/src/vim.h b/src/vim.h
index ce402f666..b59d97b95 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -2586,6 +2586,25 @@ typedef int (*opt_expand_cb_T)(optexpand_T *args, int *numMatches, char_u ***mat
#include "globals.h" // global variables and messages
#include "errors.h" // error messages

+#ifndef PROTO
+/*
+ * Return TRUE when currently using Vim9 script syntax.
+ * Does not go up the stack, a ":function" inside vim9script uses legacy
+ * syntax.
+ * Defined here as "static inline" because it is called very frequently from
+ * the eval hot path; inlining avoids the cross-file call overhead.
+ */
+ static inline int
+in_vim9script(void)
+{
+ // "sc_version" is also set when compiling a ":def" function in legacy
+ // script.
+ return (current_sctx.sc_version == SCRIPT_VERSION_VIM9
+ || (cmdmod.cmod_flags & CMOD_VIM9CMD))
+ && !(cmdmod.cmod_flags & CMOD_LEGACY);
+}
+#endif
+
/*
* If console dialog not supported, but GUI dialog is, use the GUI one.
*/
diff --git a/src/vim9script.c b/src/vim9script.c
index 4719f49f3..c4b927688 100644
--- a/src/vim9script.c
+++ b/src/vim9script.c
@@ -13,21 +13,6 @@

#include "vim.h"

-/*
- * Return TRUE when currently using Vim9 script syntax.
- * Does not go up the stack, a ":function" inside vim9script uses legacy
- * syntax.
- */
- int
-in_vim9script(void)
-{
- // "sc_version" is also set when compiling a ":def" function in legacy
- // script.
- return (current_sctx.sc_version == SCRIPT_VERSION_VIM9
- || (cmdmod.cmod_flags & CMOD_VIM9CMD))
- && !(cmdmod.cmod_flags & CMOD_LEGACY);
-}
-
#if defined(FEAT_EVAL)
/*
* Return TRUE when currently in a script with script version smaller than