From 61f76a3612db199a9eb9090c2605d8fc35ffc41c Mon Sep 17 00:00:00 2001 From: Kirill Smelkov Date: Thu, 27 Mar 2014 18:22:50 +0400 Subject: 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 # 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 Cc: Marius Storm-Olsen Cc: Johannes Sixt Cc: Johannes Schindelin Cc: Ramsay Jones Cc: Gerrit Pape Cc: Petr Salinger Cc: Jonathan Nieder Acked-by: Thomas Schwinge (GNU Hurd changes) Signed-off-by: Kirill Smelkov Signed-off-by: Junio C Hamano --- config.mak.uname | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'config.mak.uname') diff --git a/config.mak.uname b/config.mak.uname index 7d31fad24..71602ee9a 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 = -- cgit v1.2.1 From 22f4c27e68f448d5fce316a73ea3f7bab6aa1268 Mon Sep 17 00:00:00 2001 From: Kirill Smelkov Date: Wed, 9 Apr 2014 16:48:27 +0400 Subject: mingw: activate alloca Both MSVC and MINGW have alloca(3) definitions in malloc.h, so by moving win32-compat alloca.h from compat/vcbuild/include/ to compat/win32/ , which is included by both MSVC and MINGW CFLAGS, we can make alloca() work on both those Windows environments. In MINGW, malloc.h has explicit check for GNUC and if it is so, defines alloca to __builtin_alloca, so it looks like we don't need to add any code to here-shipped alloca.h to get optimum performance. Compile-tested on Windows in MSysGit. Signed-off-by: Kirill Smelkov Acked-by: Erik Faye-Lund Signed-off-by: Junio C Hamano --- config.mak.uname | 1 + 1 file changed, 1 insertion(+) (limited to 'config.mak.uname') diff --git a/config.mak.uname b/config.mak.uname index 71602ee9a..9967de66a 100644 --- a/config.mak.uname +++ b/config.mak.uname @@ -480,6 +480,7 @@ ifeq ($(uname_S),NONSTOP_KERNEL) endif ifneq (,$(findstring MINGW,$(uname_S))) pathsep = ; + HAVE_ALLOCA_H = YesPlease NO_PREAD = YesPlease NEEDS_CRYPTO_WITH_SSL = YesPlease NO_LIBGEN_H = YesPlease -- cgit v1.2.1