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[Emacs-diffs] master 365dad1: Use plain ‘static’ for Emacs C inline fun
From: |
Paul Eggert |
Subject: |
[Emacs-diffs] master 365dad1: Use plain ‘static’ for Emacs C inline functions |
Date: |
Thu, 5 Sep 2019 02:15:09 -0400 (EDT) |
branch: master
commit 365dad197bac5deec9244fd9c189d23c46c99b31
Author: Paul Eggert <address@hidden>
Commit: Paul Eggert <address@hidden>
Use plain ‘static’ for Emacs C inline functions
This improved performance of ‘make compile-always’ by 8.2%
on my platform (AMD Phenom II X4 910e, Fedora 30 x86-64).
* src/conf_post.h (INLINE, EXTERN_INLINE, INLINE_HEADER_BEGIN)
(INLINE_HEADER_END) [!EMACS_EXTERN_INLINE]: Use plain ‘static’.
---
src/conf_post.h | 43 ++++++++++++++++++++++++++++++++++---------
1 file changed, 34 insertions(+), 9 deletions(-)
diff --git a/src/conf_post.h b/src/conf_post.h
index 4af1ba9..43f9862 100644
--- a/src/conf_post.h
+++ b/src/conf_post.h
@@ -373,8 +373,13 @@ extern int emacs_setenv_TZ (char const *);
#undef noinline
#endif
-/* Use Gnulib's extern-inline module for extern inline functions.
- An include file foo.h should prepend FOO_INLINE to function
+/* INLINE marks functions defined in Emacs-internal C headers.
+ INLINE is implemented via C99-style 'extern inline' if Emacs is built
+ with -DEMACS_EXTERN_INLINE; otherwise it is implemented via 'static'.
+ EMACS_EXTERN_INLINE is no longer the default, as 'static' seems to
+ have better performance with GCC.
+
+ An include file foo.h should prepend INLINE to function
definitions, with the following overall pattern:
[#include any other .h files first.]
@@ -399,20 +404,40 @@ extern int emacs_setenv_TZ (char const *);
For Emacs, this is done by having emacs.c first '#define INLINE
EXTERN_INLINE' and then include every .h file that uses INLINE.
- The INLINE_HEADER_BEGIN and INLINE_HEADER_END suppress bogus
- warnings in some GCC versions; see ../m4/extern-inline.m4.
+ The INLINE_HEADER_BEGIN and INLINE_HEADER_END macros suppress bogus
+ warnings in some GCC versions; see ../m4/extern-inline.m4. */
+
+#ifdef EMACS_EXTERN_INLINE
+
+/* Use Gnulib's extern-inline module for extern inline functions.
C99 compilers compile functions like 'incr' as C99-style extern
inline functions. Buggy GCC implementations do something similar with
GNU-specific keywords. Buggy non-GCC compilers use static
functions, which bloats the code but is good enough. */
-#ifndef INLINE
-# define INLINE _GL_INLINE
+# ifndef INLINE
+# define INLINE _GL_INLINE
+# endif
+# define EXTERN_INLINE _GL_EXTERN_INLINE
+# define INLINE_HEADER_BEGIN _GL_INLINE_HEADER_BEGIN
+# define INLINE_HEADER_END _GL_INLINE_HEADER_END
+
+#else
+
+/* Use 'static' instead of 'extern inline' because 'static' typically
+ has better performance for Emacs. Do not use the 'inline' keyword,
+ as modern compilers inline automatically. ATTRIBUTE_UNUSED
+ pacifies gcc -Wunused-function. */
+
+# ifndef INLINE
+# define INLINE EXTERN_INLINE
+# endif
+# define EXTERN_INLINE static ATTRIBUTE_UNUSED
+# define INLINE_HEADER_BEGIN
+# define INLINE_HEADER_END
+
#endif
-#define EXTERN_INLINE _GL_EXTERN_INLINE
-#define INLINE_HEADER_BEGIN _GL_INLINE_HEADER_BEGIN
-#define INLINE_HEADER_END _GL_INLINE_HEADER_END
/* 'int x UNINIT;' is equivalent to 'int x;', except it cajoles GCC
into not warning incorrectly about use of an uninitialized variable. */
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