Merge pull request #2368 from facebook/progressive_libzstd

faster rebuild of libzstd

lib/Makefile

@@ -10,13 +10,13 @@
 
 Q = $(if $(filter 1,$(V) $(VERBOSE)),,@)
 
-# When cross-compiling from linux to windows, you might
+# When cross-compiling from linux to windows,
-# need to specify this as "Windows." Fedora build fails
+# you might need to specify this as "Windows."
-# without it.
+# Fedora build fails without it.
 #
-# Note: mingw-w64 build from linux to windows does not
+# Note: mingw-w64 build from linux to windows
-# fail on other tested distros (ubuntu, debian) even
+# does not fail on other tested distros (ubuntu, debian)
-# without manually specifying the TARGET_SYSTEM.
+# even without manually specifying the TARGET_SYSTEM.
 TARGET_SYSTEM ?= $(OS)
 
 # Version numbers
@@ -164,7 +164,17 @@ endif
 endif
 CPPFLAGS  += -DZSTD_LEGACY_SUPPORT=$(ZSTD_LEGACY_SUPPORT)
 
-ZSTD_OBJ   := $(patsubst %.c,%.o,$(ZSTD_FILES))
+ZSTD_LOCAL_SRC := $(notdir $(ZSTD_FILES))
+ZSTD_LOCAL_OBJ := $(ZSTD_LOCAL_SRC:.c=.o)
+
+ZSTD_SUBDIR := common compress decompress dictBuilder legacy deprecated
+vpath %.c $(ZSTD_SUBDIR)
+
+BUILD_DIR ?= obj
+ZSTD_DYNLIB_DIR := $(BUILD_DIR)/dynlib
+ZSTD_DYNLIB_OBJ := $(addprefix $(ZSTD_DYNLIB_DIR)/, $(ZSTD_LOCAL_OBJ))
+ZSTD_STATLIB_DIR := $(BUILD_DIR)/statlib
+ZSTD_STATLIB_OBJ := $(addprefix $(ZSTD_STATLIB_DIR)/, $(ZSTD_LOCAL_OBJ))
 
 # macOS linker doesn't support -soname, and use different extension
 # see : https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/DynamicLibraries/100-Articles/DynamicLibraryDesignGuidelines.html
@@ -191,7 +201,7 @@ lib-all: all
 all: lib
 
 libzstd.a: ARFLAGS = rcs
-libzstd.a: $(ZSTD_OBJ)
+libzstd.a: $(ZSTD_STATLIB_OBJ)
 	@echo compiling static library
 	$(Q)$(AR) $(ARFLAGS) $@ $^
 
@@ -205,8 +215,9 @@ $(LIBZSTD): $(ZSTD_FILES)
 else
 
 LIBZSTD = libzstd.$(SHARED_EXT_VER)
-$(LIBZSTD): LDFLAGS += -shared -fPIC -fvisibility=hidden
+$(LIBZSTD): CFLAGS += -fPIC
-$(LIBZSTD): $(ZSTD_FILES)
+$(LIBZSTD): LDFLAGS += -shared -fvisibility=hidden
+$(LIBZSTD): $(ZSTD_DYNLIB_OBJ)
 	@echo compiling dynamic library $(LIBVER)
 	$(Q)$(CC) $(FLAGS) $^ $(LDFLAGS) $(SONAME_FLAGS) -o $@
 	@echo creating versioned links
@@ -221,6 +232,7 @@ libzstd : $(LIBZSTD)
 .PHONY: lib
 lib : libzstd.a libzstd
 
+
 # note : do not define lib-mt or lib-release as .PHONY
 # make does not consider implicit pattern rule for .PHONY target
 
@@ -234,6 +246,28 @@ lib : libzstd.a libzstd
 	@echo release build completed
 
 
+# Generate .h dependencies automatically
+
+DEPFLAGS = -MT $@ -MMD -MP -MF
+
+$(ZSTD_DYNLIB_DIR)/%.o : %.c $(ZSTD_DYNLIB_DIR)/%.d | $(ZSTD_DYNLIB_DIR)
+	@echo $@
+	$(Q)$(COMPILE.c) $(DEPFLAGS) $(ZSTD_DYNLIB_DIR)/$*.d $(OUTPUT_OPTION) $<
+
+$(ZSTD_STATLIB_DIR)/%.o : %.c $(ZSTD_STATLIB_DIR)/%.d | $(ZSTD_STATLIB_DIR)
+	@echo $@
+	$(Q)$(COMPILE.c) $(DEPFLAGS) $(ZSTD_STATLIB_DIR)/$*.d $(OUTPUT_OPTION) $<
+
+MKDIR ?= mkdir
+$(ZSTD_DYNLIB_DIR) $(ZSTD_STATLIB_DIR):
+	$(Q)$(MKDIR) -p $@
+
+DEPFILES := $(ZSTD_DYNLIB_OBJ:.o=.d) $(ZSTD_STATLIB_OBJ:.o=.d)
+$(DEPFILES):
+
+include $(wildcard $(DEPFILES))
+
+
 # Special case : building library in single-thread mode _and_ without zstdmt_compress.c
 ZSTDMT_FILES = compress/zstdmt_compress.c
 ZSTD_NOMT_FILES = $(filter-out $(ZSTDMT_FILES),$(ZSTD_FILES))
@@ -248,6 +282,7 @@ clean:
 	$(Q)$(RM) core *.o *.a *.gcda *.$(SHARED_EXT) *.$(SHARED_EXT).* libzstd.pc
 	$(Q)$(RM) dll/libzstd.dll dll/libzstd.lib libzstd-nomt*
 	$(Q)$(RM) common/*.o compress/*.o decompress/*.o dictBuilder/*.o legacy/*.o deprecated/*.o
+	$(Q)$(RM) -r $(ZSTD_STATLIB_DIR)/* $(ZSTD_DYNLIB_DIR)/*
 	@echo Cleaning library completed
 
 #-----------------------------------------------------------------------------
@@ -277,7 +312,7 @@ ifeq (,$(PCLIBDIR))
 # Additional prefix check is required, since the empty string is technically a
 # valid PCLIBDIR
 ifeq (,$(shell echo "$(LIBDIR)" | sed -n $(SED_ERE_OPT) -e "\\@^$(EXEC_PREFIX)(/|$$)@ p"))
-$(error configured libdir ($(LIBDIR)) is outside of prefix ($(PREFIX)), can't generate pkg-config file)
+$(error configured libdir ($(LIBDIR)) is outside of prefix ($(EXEC_PREFIX)), can't generate pkg-config file)
 endif
 endif
 
@@ -285,7 +320,7 @@ ifeq (,$(PCINCDIR))
 # Additional prefix check is required, since the empty string is technically a
 # valid PCINCDIR
 ifeq (,$(shell echo "$(INCLUDEDIR)" | sed -n $(SED_ERE_OPT) -e "\\@^$(PREFIX)(/|$$)@ p"))
-$(error configured includedir ($(INCLUDEDIR)) is outside of exec_prefix ($(EXEC_PREFIX)), can't generate pkg-config file)
+$(error configured includedir ($(INCLUDEDIR)) is outside of exec_prefix ($(PREFIX)), can't generate pkg-config file)
 endif
 endif