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Merge branch 'ak/gcc46-profile-feedback'

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* ak/gcc46-profile-feedback:
  Add explanation of the profile feedback build to the README
  Add profile feedback build to git
  Add option to disable NORETURN
This commit is contained in:
Junio C Hamano 2011-07-19 09:32:52 -07:00
commit d37b2991b1
3 changed files with 36 additions and 1 deletions
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13
INSTALL
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@ -25,6 +25,19 @@ set up install paths (via config.mak.autogen), so you can write instead
$ make all doc ;# as yourself
# make install install-doc install-html;# as root
If you're willing to trade off (much) longer build time for a later
faster git you can also do a profile feedback build with
$ make profile-all
# make prefix=... install
This will run the complete test suite as training workload and then
rebuild git with the generated profile feedback. This results in a git
which is a few percent faster on CPU intensive workloads. This
may be a good tradeoff for distribution packagers.
Note that the profile feedback build stage currently generates
a lot of additional compiler warnings.
Issues of note:

22
Makefile
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@ -153,6 +153,9 @@ all::
# that tells runtime paths to dynamic libraries;
# "-Wl,-rpath=/path/lib" is used instead.
#
# Define NO_NORETURN if using buggy versions of gcc 4.6+ and profile feedback,
# as the compiler can crash (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49299)
#
# Define USE_NSEC below if you want git to care about sub-second file mtimes
# and ctimes. Note that you need recent glibc (at least 2.2.4) for this, and
# it will BREAK YOUR LOCAL DIFFS! show-diff and anything using it will likely
@ -1378,6 +1381,9 @@ endif
ifdef USE_ST_TIMESPEC
BASIC_CFLAGS += -DUSE_ST_TIMESPEC
endif
ifdef NO_NORETURN
BASIC_CFLAGS += -DNO_NORETURN
endif
ifdef NO_NSEC
BASIC_CFLAGS += -DNO_NSEC
endif
@ -2499,3 +2505,19 @@ cover_db: coverage-report
cover_db_html: cover_db
cover -report html -outputdir cover_db_html cover_db
### profile feedback build
#
.PHONY: profile-all profile-clean
PROFILE_GEN_CFLAGS := $(CFLAGS) -fprofile-generate -DNO_NORETURN=1
PROFILE_USE_CFLAGS := $(CFLAGS) -fprofile-use -fprofile-correction -DNO_NORETURN=1
profile-clean:
$(RM) $(addsuffix *.gcda,$(object_dirs))
$(RM) $(addsuffix *.gcno,$(object_dirs))
profile-all: profile-clean
$(MAKE) CFLAGS="$(PROFILE_GEN_CFLAGS)" all
$(MAKE) CFLAGS="$(PROFILE_GEN_CFLAGS)" -j1 test
$(MAKE) CFLAGS="$(PROFILE_USE_CFLAGS)" all

2
git-compat-util.h
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@ -222,7 +222,7 @@ extern char *gitbasename(char *);
#if __HP_cc >= 61000
#define NORETURN __attribute__((noreturn))
#define NORETURN_PTR
#elif defined(__GNUC__)
#elif defined(__GNUC__) && !defined(NO_NORETURN)
#define NORETURN __attribute__((__noreturn__))
#define NORETURN_PTR __attribute__((__noreturn__))
#elif defined(_MSC_VER)