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| author | Kirill Smelkov <kirr@mns.spb.ru> | 2014-03-27 18:22:50 +0400 |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2014-03-27 11:54:01 -0700 |
| commit | 61f76a3612db199a9eb9090c2605d8fc35ffc41c (patch) | |
| tree | fc5e216179e5fd11343f0b59b77b3da354ece5c9 /config.mak.uname | |
| parent | 12cd81743dc4645ef909b0c38582f5714c9a8ff7 (diff) | |
| download | git-61f76a3612db199a9eb9090c2605d8fc35ffc41c.tar.gz | |
Portable alloca for Git
In the next patch we'll have to use alloca() for performance reasons,
but since alloca is non-standardized and is not portable, let's have a
trick with compatibility wrappers:
1. at configure time, determine, do we have working alloca() through
alloca.h, and define
#define HAVE_ALLOCA_H
if yes.
2. in code
#ifdef HAVE_ALLOCA_H
# include <alloca.h>
# define xalloca(size) (alloca(size))
# define xalloca_free(p) do {} while(0)
#else
# define xalloca(size) (xmalloc(size))
# define xalloca_free(p) (free(p))
#endif
and use it like
func() {
p = xalloca(size);
...
xalloca_free(p);
}
This way, for systems, where alloca is available, we'll have optimal
on-stack allocations with fast executions. On the other hand, on
systems, where alloca is not available, this gracefully fallbacks to
xmalloc/free.
Both autoconf and config.mak.uname configurations were updated. For
autoconf, we are not bothering considering cases, when no alloca.h is
available, but alloca() works some other way - its simply alloca.h is
available and works or not, everything else is deep legacy.
For config.mak.uname, I've tried to make my almost-sure guess for where
alloca() is available, but since I only have access to Linux it is the
only change I can be sure about myself, with relevant to other changed
systems people Cc'ed.
NOTE
SunOS and Windows had explicit -DHAVE_ALLOCA_H in their configurations.
I've changed that to now-common HAVE_ALLOCA_H=YesPlease which should be
correct.
Cc: Brandon Casey <drafnel@gmail.com>
Cc: Marius Storm-Olsen <mstormo@gmail.com>
Cc: Johannes Sixt <j6t@kdbg.org>
Cc: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Cc: Gerrit Pape <pape@smarden.org>
Cc: Petr Salinger <Petr.Salinger@seznam.cz>
Cc: Jonathan Nieder <jrnieder@gmail.com>
Acked-by: Thomas Schwinge <thomas@codesourcery.com> (GNU Hurd changes)
Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'config.mak.uname')
| -rw-r--r-- | config.mak.uname | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/config.mak.uname b/config.mak.uname index 7d31fad241..71602ee9a1 100644 --- a/config.mak.uname +++ b/config.mak.uname @@ -28,6 +28,7 @@ ifeq ($(uname_S),OSF1) NO_NSEC = YesPlease endif ifeq ($(uname_S),Linux) + HAVE_ALLOCA_H = YesPlease NO_STRLCPY = YesPlease NO_MKSTEMPS = YesPlease HAVE_PATHS_H = YesPlease @@ -35,6 +36,7 @@ ifeq ($(uname_S),Linux) HAVE_DEV_TTY = YesPlease endif ifeq ($(uname_S),GNU/kFreeBSD) + HAVE_ALLOCA_H = YesPlease NO_STRLCPY = YesPlease NO_MKSTEMPS = YesPlease HAVE_PATHS_H = YesPlease @@ -103,6 +105,7 @@ ifeq ($(uname_S),SunOS) NEEDS_NSL = YesPlease SHELL_PATH = /bin/bash SANE_TOOL_PATH = /usr/xpg6/bin:/usr/xpg4/bin + HAVE_ALLOCA_H = YesPlease NO_STRCASESTR = YesPlease NO_MEMMEM = YesPlease NO_MKDTEMP = YesPlease @@ -146,7 +149,7 @@ ifeq ($(uname_S),SunOS) endif INSTALL = /usr/ucb/install TAR = gtar - BASIC_CFLAGS += -D__EXTENSIONS__ -D__sun__ -DHAVE_ALLOCA_H + BASIC_CFLAGS += -D__EXTENSIONS__ -D__sun__ endif ifeq ($(uname_O),Cygwin) ifeq ($(shell expr "$(uname_R)" : '1\.[1-6]\.'),4) @@ -166,6 +169,7 @@ ifeq ($(uname_O),Cygwin) else NO_REGEX = UnfortunatelyYes endif + HAVE_ALLOCA_H = YesPlease NEEDS_LIBICONV = YesPlease NO_FAST_WORKING_DIRECTORY = UnfortunatelyYes NO_ST_BLOCKS_IN_STRUCT_STAT = YesPlease @@ -239,6 +243,7 @@ ifeq ($(uname_S),AIX) endif ifeq ($(uname_S),GNU) # GNU/Hurd + HAVE_ALLOCA_H = YesPlease NO_STRLCPY = YesPlease NO_MKSTEMPS = YesPlease HAVE_PATHS_H = YesPlease @@ -316,6 +321,7 @@ endif ifeq ($(uname_S),Windows) GIT_VERSION := $(GIT_VERSION).MSVC pathsep = ; + HAVE_ALLOCA_H = YesPlease NO_PREAD = YesPlease NEEDS_CRYPTO_WITH_SSL = YesPlease NO_LIBGEN_H = YesPlease @@ -363,7 +369,7 @@ ifeq ($(uname_S),Windows) COMPAT_OBJS = compat/msvc.o compat/winansi.o \ compat/win32/pthread.o compat/win32/syslog.o \ compat/win32/dirent.o - COMPAT_CFLAGS = -D__USE_MINGW_ACCESS -DNOGDI -DHAVE_STRING_H -DHAVE_ALLOCA_H -Icompat -Icompat/regex -Icompat/win32 -DSTRIP_EXTENSION=\".exe\" + COMPAT_CFLAGS = -D__USE_MINGW_ACCESS -DNOGDI -DHAVE_STRING_H -Icompat -Icompat/regex -Icompat/win32 -DSTRIP_EXTENSION=\".exe\" BASIC_LDFLAGS = -IGNORE:4217 -IGNORE:4049 -NOLOGO -SUBSYSTEM:CONSOLE -NODEFAULTLIB:MSVCRT.lib EXTLIBS = user32.lib advapi32.lib shell32.lib wininet.lib ws2_32.lib PTHREAD_LIBS = |