Makefile: Generate dependency information implicitly while compiling

This updates the dependecy information on each successive recompile.

When building with MSVC, dependency information is generated with
a separate command just like before, but done together with
compiling each object file. (This is quite similar to how ffmpeg does
the same.)

This avoids the serial dependency generation step. In slow
environments (in particular if using MSVC) it could take a notable
amount of time; this can now all be done in parallel.

In one example, this reduces the time for a full build from clean
with MSVC (wrapped in wine) from 23 seconds down to 9 seconds,
thanks to parallelism. (For non-parallel builds, it doesn't make
much of a difference.)

.gitignore

@@ -1,5 +1,6 @@
 *~
 *.a
+*.d
 *.diff
 *.orig
 *.rej

Makefile

@@ -311,39 +311,46 @@ example$(EXE): $(OBJEXAMPLE) $(LIBX264)
 $(OBJS) $(OBJSO): CFLAGS += $(CFLAGSSO)
 $(OBJCLI): CFLAGS += $(CFLAGSCLI)
 
-$(OBJS) $(OBJASM) $(OBJSO) $(OBJCLI) $(OBJCHK) $(OBJCHK_8) $(OBJCHK_10) $(OBJEXAMPLE): .depend
+ALLOBJS = $(OBJS) $(OBJASM) $(OBJSO) $(OBJCLI) $(OBJCHK) $(OBJCHK_8) $(OBJCHK_10) $(OBJEXAMPLE)
+$(ALLOBJS): $(GENERATED)
 
 %.o: %.c
-	$(CC) $(CFLAGS) -c $< $(CC_O)
+	$(DEPCMD)
+	$(CC) $(CFLAGS) -c $< $(CC_O) $(DEPFLAGS)
 
 %-8.o: %.c
-	$(CC) $(CFLAGS) -c $< $(CC_O) -DHIGH_BIT_DEPTH=0 -DBIT_DEPTH=8
+	$(DEPCMD)
+	$(CC) $(CFLAGS) -c $< $(CC_O) $(DEPFLAGS) -DHIGH_BIT_DEPTH=0 -DBIT_DEPTH=8
 
 %-10.o: %.c
-	$(CC) $(CFLAGS) -c $< $(CC_O) -DHIGH_BIT_DEPTH=1 -DBIT_DEPTH=10
+	$(DEPCMD)
+	$(CC) $(CFLAGS) -c $< $(CC_O) $(DEPFLAGS) -DHIGH_BIT_DEPTH=1 -DBIT_DEPTH=10
 
 %.o: %.asm common/x86/x86inc.asm common/x86/x86util.asm
-	$(AS) $(ASFLAGS) -o $@ $<
+	$(AS) $(ASFLAGS) -o $@ $< -MD $(@:.o=.d)
 	-@ $(if $(STRIP), $(STRIP) -x $@) # delete local/anonymous symbols, so they don't show up in oprofile
 
 %-8.o: %.asm common/x86/x86inc.asm common/x86/x86util.asm
-	$(AS) $(ASFLAGS) -o $@ $< -DBIT_DEPTH=8 -Dprivate_prefix=x264_8
+	$(AS) $(ASFLAGS) -o $@ $< -MD $(@:.o=.d) -DBIT_DEPTH=8 -Dprivate_prefix=x264_8
 	-@ $(if $(STRIP), $(STRIP) -x $@)
 
 %-10.o: %.asm common/x86/x86inc.asm common/x86/x86util.asm
-	$(AS) $(ASFLAGS) -o $@ $< -DBIT_DEPTH=10 -Dprivate_prefix=x264_10
+	$(AS) $(ASFLAGS) -o $@ $< -MD $(@:.o=.d) -DBIT_DEPTH=10 -Dprivate_prefix=x264_10
 	-@ $(if $(STRIP), $(STRIP) -x $@)
 
 %.o: %.S
-	$(AS) $(ASFLAGS) -o $@ $<
+	$(DEPCMD)
+	$(AS) $(ASFLAGS) -o $@ $< $(DEPFLAGS)
 	-@ $(if $(STRIP), $(STRIP) -x $@) # delete local/anonymous symbols, so they don't show up in oprofile
 
 %-8.o: %.S
-	$(AS) $(ASFLAGS) -o $@ $< -DHIGH_BIT_DEPTH=0 -DBIT_DEPTH=8
+	$(DEPCMD)
+	$(AS) $(ASFLAGS) -o $@ $< $(DEPFLAGS) -DHIGH_BIT_DEPTH=0 -DBIT_DEPTH=8
 	-@ $(if $(STRIP), $(STRIP) -x $@)
 
 %-10.o: %.S
-	$(AS) $(ASFLAGS) -o $@ $< -DHIGH_BIT_DEPTH=1 -DBIT_DEPTH=10
+	$(DEPCMD)
+	$(AS) $(ASFLAGS) -o $@ $< $(DEPFLAGS) -DHIGH_BIT_DEPTH=1 -DBIT_DEPTH=10
 	-@ $(if $(STRIP), $(STRIP) -x $@)
 
 %.dll.o: %.rc x264.h
@@ -352,34 +359,19 @@ $(OBJS) $(OBJASM) $(OBJSO) $(OBJCLI) $(OBJCHK) $(OBJCHK_8) $(OBJCHK_10) $(OBJEXA
 %.o: %.rc x264.h x264res.manifest
 	$(RC) $(RCFLAGS)$@ $<
 
-.depend: config.mak $(GENERATED)
-	@rm -f .depend
-	@echo 'dependency file generation...'
-ifeq ($(COMPILER),CL)
-	@$(foreach SRC, $(addprefix $(SRCPATH)/, $(SRCS) $(SRCCLI) $(SRCSO) $(SRCEXAMPLE)), $(SRCPATH)/tools/msvsdepend.sh "$(CC)" "$(CFLAGS)" "$(SRC)" "$(SRC:$(SRCPATH)/%.c=%.o)" 1>> .depend;)
-ifneq ($(findstring HAVE_BITDEPTH8 1, $(CONFIG)),)
-	@$(foreach SRC, $(addprefix $(SRCPATH)/, $(SRCS_X) $(SRCS_8) $(SRCCLI_X) $(SRCCHK_X)), $(SRCPATH)/tools/msvsdepend.sh "$(CC)" "$(CFLAGS)" "$(SRC)" "$(SRC:$(SRCPATH)/%.c=%-8.o)" 1>> .depend;)
-endif
-ifneq ($(findstring HAVE_BITDEPTH10 1, $(CONFIG)),)
-	@$(foreach SRC, $(addprefix $(SRCPATH)/, $(SRCS_X) $(SRCCLI_X) $(SRCCHK_X)), $(SRCPATH)/tools/msvsdepend.sh "$(CC)" "$(CFLAGS)" "$(SRC)" "$(SRC:$(SRCPATH)/%.c=%-10.o)" 1>> .depend;)
-endif
-else
-	@$(foreach SRC, $(addprefix $(SRCPATH)/, $(SRCS) $(SRCCLI) $(SRCSO) $(SRCEXAMPLE)), $(CC) $(CFLAGS) $(SRC) $(DEPMT) $(SRC:$(SRCPATH)/%.c=%.o) $(DEPMM) 1>> .depend;)
-ifneq ($(findstring HAVE_BITDEPTH8 1, $(CONFIG)),)
-	@$(foreach SRC, $(addprefix $(SRCPATH)/, $(SRCS_X) $(SRCS_8) $(SRCCLI_X) $(SRCCHK_X)), $(CC) $(CFLAGS) $(SRC) $(DEPMT) $(SRC:$(SRCPATH)/%.c=%-8.o) $(DEPMM) 1>> .depend;)
-endif
-ifneq ($(findstring HAVE_BITDEPTH10 1, $(CONFIG)),)
-	@$(foreach SRC, $(addprefix $(SRCPATH)/, $(SRCS_X) $(SRCCLI_X) $(SRCCHK_X)), $(CC) $(CFLAGS) $(SRC) $(DEPMT) $(SRC:$(SRCPATH)/%.c=%-10.o) $(DEPMM) 1>> .depend;)
-endif
-endif
-
 config.mak:
 	./configure
 
-depend: .depend
+# This is kept as a no-op
-ifneq ($(wildcard .depend),)
+depend:
-include .depend
+	@echo "make depend" is handled implicitly now
-endif
+
+-include $(wildcard $(ALLOBJS:.o=.d))
+
+# Dummy rule to avoid failing, if the dependency files specify dependencies on
+# a removed .h file.
+%.h:
+	@:
 
 OBJPROF = $(OBJS) $(OBJSO) $(OBJCLI)
 # These should cover most of the important codepaths
@@ -412,11 +404,12 @@ endif
 endif
 
 clean:
-	rm -f $(OBJS) $(OBJASM) $(OBJCLI) $(OBJSO) $(GENERATED) .depend TAGS
+	rm -f $(OBJS) $(OBJASM) $(OBJCLI) $(OBJSO) $(GENERATED) TAGS
 	rm -f $(SONAME) *.a *.lib *.exp *.pdb x264$(EXE) x264_lookahead.clbin
 	rm -f checkasm8$(EXE) checkasm10$(EXE) $(OBJCHK) $(OBJCHK_8) $(OBJCHK_10)
 	rm -f example$(EXE) $(OBJEXAMPLE)
 	rm -f $(OBJPROF:%.o=%.gcda) $(OBJPROF:%.o=%.gcno) *.dyn pgopti.dpi pgopti.dpi.lock *.pgd *.pgc
+	rm -f $(ALLOBJS:%.o=%.d)
 
 distclean: clean
 	rm -f config.mak x264_config.h config.h config.log x264.pc x264.def

configure

@@ -1496,9 +1496,9 @@ else
     CLI_LIBX264='$(LIBX264)'
 fi
 
-DEPMM="${QPRE}MM"
-DEPMT="${QPRE}MT"
 if [ $compiler_style = MS ]; then
+    DEPFLAGS=""
+    DEPCMD='@$(SRCPATH)/tools/msvsdepend.sh "$(CC)" "$(CFLAGS)" "$<" "$@" > $(@:.o=.d)'
     AR="lib.exe -nologo -out:"
     LD="link.exe -out:"
     if [ $compiler = ICL ]; then
@@ -1522,7 +1522,8 @@ if [ $compiler_style = MS ]; then
         CFLAGS="-DNDEBUG $CFLAGS"
     fi
 else # gcc/icc
-    DEPMM="$DEPMM -g0"
+    DEPFLAGS="${QPRE}MMD ${QPRE}MF"' $(@:.o=.d)'
+    DEPCMD=""
     AR="$AR rc "
     LD="$CC -o "
     LIBX264=libx264.a
@@ -1575,8 +1576,8 @@ CFLAGSSO=$CFLAGSSO
 CFLAGSCLI=$CFLAGSCLI
 COMPILER=$compiler
 COMPILER_STYLE=$compiler_style
-DEPMM=$DEPMM
+DEPCMD=$DEPCMD
-DEPMT=$DEPMT
+DEPFLAGS=$DEPFLAGS
 LD=$LD
 LDFLAGS=$LDFLAGS
 LDFLAGSCLI=$LDFLAGSCLI