Merge branch 'sg/precompile-git-compat-util' into jch

The 'Makefile' has been taught to precompile 'git-compat-util.h' to
speed up overall compilation, while excluding sources that do not
include the compatibility header.

* sg/precompile-git-compat-util:
  Makefile: precompile "git-compat-util.h"
  Makefile: reintroduce REFTABLE_OBJS
  cmake: remove any "$(*_OBJS)" variables when parsing Makefile for sources
  Makefile: remove XDIFF_OBJS initialization

.gitignore

@@ -233,6 +233,7 @@
 /.vscode/
 /tags
 /TAGS
+/tools/precompiled.h.gch
 /cscope*
 /compile_commands.json
 /.cache/

Makefile

@@ -314,6 +314,9 @@ include shared.mak
 # dependency rules.  The default is "auto", which means to use computed header
 # dependencies if your compiler is detected to support it.
 #
+# Define NO_PRECOMPILED_HEADER if you want to build Git without precompiling
+# "git-compat-util.h".
+#
 # Define NATIVE_CRLF if your platform uses CRLF for line endings.
 #
 # Define GIT_USER_AGENT if you want to change how git identifies itself during
@@ -688,7 +691,6 @@ BUILTIN_OBJS =
 BUILT_INS =
 COMPAT_CFLAGS =
 COMPAT_OBJS =
-XDIFF_OBJS =
 GENERATED_H =
 EXTRA_CPPFLAGS =
 FUZZ_OBJS =
@@ -701,6 +703,7 @@ OBJECTS =
 OTHER_PROGRAMS =
 PROGRAM_OBJS =
 PROGRAMS =
+REFTABLE_OBJS =
 RUST_SOURCES =
 EXCLUDED_PROGRAMS =
 SCRIPT_PERL =
@@ -1278,20 +1281,6 @@ LIB_OBJS += refs/iterator.o
 LIB_OBJS += refs/packed-backend.o
 LIB_OBJS += refs/ref-cache.o
 LIB_OBJS += refspec.o
-LIB_OBJS += reftable/basics.o
-LIB_OBJS += reftable/block.o
-LIB_OBJS += reftable/blocksource.o
-LIB_OBJS += reftable/error.o
-LIB_OBJS += reftable/fsck.o
-LIB_OBJS += reftable/iter.o
-LIB_OBJS += reftable/merged.o
-LIB_OBJS += reftable/pq.o
-LIB_OBJS += reftable/record.o
-LIB_OBJS += reftable/stack.o
-LIB_OBJS += reftable/system.o
-LIB_OBJS += reftable/table.o
-LIB_OBJS += reftable/tree.o
-LIB_OBJS += reftable/writer.o
 LIB_OBJS += remote.o
 LIB_OBJS += repack.o
 LIB_OBJS += repack-cruft.o
@@ -1380,6 +1369,23 @@ LIB_OBJS += xdiff/xpatience.o
 LIB_OBJS += xdiff/xprepare.o
 LIB_OBJS += xdiff/xutils.o
 
+REFTABLE_OBJS += reftable/basics.o
+REFTABLE_OBJS += reftable/block.o
+REFTABLE_OBJS += reftable/blocksource.o
+REFTABLE_OBJS += reftable/error.o
+REFTABLE_OBJS += reftable/fsck.o
+REFTABLE_OBJS += reftable/iter.o
+REFTABLE_OBJS += reftable/merged.o
+REFTABLE_OBJS += reftable/pq.o
+REFTABLE_OBJS += reftable/record.o
+REFTABLE_OBJS += reftable/stack.o
+REFTABLE_OBJS += reftable/system.o
+REFTABLE_OBJS += reftable/table.o
+REFTABLE_OBJS += reftable/tree.o
+REFTABLE_OBJS += reftable/writer.o
+
+LIB_OBJS += $(REFTABLE_OBJS)
+
 BUILTIN_OBJS += builtin/add.o
 BUILTIN_OBJS += builtin/am.o
 BUILTIN_OBJS += builtin/annotate.o
@@ -2892,8 +2898,15 @@ endif
 .PHONY: objects
 objects: $(OBJECTS)
 
-dep_files := $(foreach f,$(OBJECTS),$(dir $f).depend/$(notdir $f).d)
-dep_dirs := $(addsuffix .depend,$(sort $(dir $(OBJECTS))))
+PRECOMPILED_HEADER := tools/precompiled.h
+PRECOMPILED_HEADER_GCH := $(addsuffix .gch,$(PRECOMPILED_HEADER))
+
+ifndef NO_PRECOMPILED_HEADER
+PRECOMPILED_HEADER_USERS := $(filter-out $(COMPAT_OBJS) $(REFTABLE_OBJS) $(patsubst %.c,%.o,$(THIRD_PARTY_SOURCES)),$(OBJECTS))
+endif
+
+dep_files := $(foreach f,$(OBJECTS) $(PRECOMPILED_HEADER_GCH),$(dir $f).depend/$(notdir $f).d)
+dep_dirs := $(addsuffix .depend,$(sort $(dir $(OBJECTS) $(PRECOMPILED_HEADER_GCH))))
 
 ifeq ($(uname_S),Darwin)
 	dep_dirs += $(addsuffix .depend,$(sort $(dir contrib/credential/osxkeychain/git-credential-osxkeychain.o)))
@@ -2927,7 +2940,13 @@ missing_compdb_dir =
 compdb_args =
 endif
 
-$(OBJECTS): %.o: %.c GIT-CFLAGS $(missing_dep_dirs) $(missing_compdb_dir)
+$(PRECOMPILED_HEADER_GCH): %.gch: % GIT-CFLAGS $(missing_dep_dirs) $(missing_compdb_dir)
+	$(QUIET_CC)$(CC) -o $@ -c $(dep_args) $(compdb_args) $(ALL_CFLAGS) $<
+
+$(PRECOMPILED_HEADER_USERS): %.o: %.c $(PRECOMPILED_HEADER_GCH) GIT-CFLAGS $(missing_dep_dirs) $(missing_compdb_dir)
+	$(QUIET_CC)$(CC) -o $*.o -c -include $(PRECOMPILED_HEADER) -Winvalid-pch $(dep_args) $(compdb_args) $(ALL_CFLAGS) $(EXTRA_CPPFLAGS) $<
+
+$(filter-out $(PRECOMPILED_HEADER_USERS),$(OBJECTS)): %.o: %.c GIT-CFLAGS $(missing_dep_dirs) $(missing_compdb_dir)
 	$(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(compdb_args) $(ALL_CFLAGS) $(EXTRA_CPPFLAGS) $<
 
 %.s: %.c GIT-CFLAGS FORCE
@@ -2941,7 +2960,7 @@ ifneq ($(dep_files_present),)
 include $(dep_files_present)
 endif
 else
-$(OBJECTS): $(LIB_H) $(GENERATED_H)
+$(OBJECTS) $(PRECOMPILED_HEADER_GCH): $(LIB_H) $(GENERATED_H)
 endif
 
 ifeq ($(GENERATE_COMPILATION_DATABASE),yes)
@@ -3895,7 +3914,7 @@ clean: profile-clean coverage-clean cocciclean
 	$(RM) GIT-TEST-SUITES
 	$(RM) po/git.pot po/git-core.pot
 	$(RM) git.rc git.res
-	$(RM) $(OBJECTS)
+	$(RM) $(OBJECTS) $(PRECOMPILED_HEADER_GCH)
 	$(RM) headless-git.o
 	$(RM) $(LIB_FILE)
 	$(RM) $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS) $(OTHER_PROGRAMS)

contrib/buildsystems/CMakeLists.txt

@@ -102,7 +102,7 @@ project(git
 macro(parse_makefile_for_sources list_var makefile regex)
 	file(STRINGS ${makefile} ${list_var} REGEX "^${regex} \\+=(.*)")
 	string(REPLACE "${regex} +=" "" ${list_var} ${${list_var}})
-	string(REPLACE "$(COMPAT_OBJS)" "" ${list_var} ${${list_var}}) #remove "$(COMPAT_OBJS)" This is only for libgit.
+	string(REGEX REPLACE "\\$\\([^)]*_OBJS\\)" "" ${list_var} ${${list_var}}) # remove any "$(*_OBJS)" variables
 	string(STRIP ${${list_var}} ${list_var}) #remove trailing/leading whitespaces
 	string(REPLACE ".o" ".c;" ${list_var} ${${list_var}}) #change .o to .c, ; is for converting the string into a list
 	list(TRANSFORM ${list_var} STRIP) #remove trailing/leading whitespaces for each element in list
@@ -675,6 +675,10 @@ include_directories(${CMAKE_BINARY_DIR})
 #libgit
 parse_makefile_for_sources(libgit_SOURCES ${CMAKE_SOURCE_DIR}/Makefile "LIB_OBJS")
 
+#reftable
+parse_makefile_for_sources(reftable_SOURCES ${CMAKE_SOURCE_DIR}/Makefile "REFTABLE_OBJS")
+list(APPEND libgit_SOURCES ${reftable_SOURCES})
+
 list(TRANSFORM libgit_SOURCES PREPEND "${CMAKE_SOURCE_DIR}/")
 list(TRANSFORM compat_SOURCES PREPEND "${CMAKE_SOURCE_DIR}/")