Build: generate .d file at the same time as object is created

Currently, .d files are generated before any objects are built.
So, IS_ANYTHING_TO_BUILD flag is needed to avoid such processing for
non-build targets.

There is a cleverer way; just create a .d file simultaneously when
the corresponding object is created.  No need to have separate rules
for .d files.

This commit will also fix a bug; -D$(IMAGE) is defined for $(OBJ),
but not for $(PREREQUISITES).  So, .d files are generated with
different macro sets from those for .o files, then wrong .d files
are generated.

For example, in lib/cpus/aarch64/cpu_helpers.S

  #if IMAGE_BL31
  #include <cpu_data.h>
  #endif

<cpu_data.h> is parsed for the object when built for BL31, but the
.d file does not pick up that dependency.

With this commit, the compiler will generate .o and .d at the same
time, guaranteeing they are generated under the same circumstances.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

make_helpers/build_macros.mk

@@ -184,24 +184,7 @@ endef
 # Auxiliary macros to build TF images from sources
 ################################################################################
 
-# If no goal is specified in the command line, .DEFAULT_GOAL is used.
-# .DEFAULT_GOAL is defined in the main Makefile before including this file.
-ifeq ($(MAKECMDGOALS),)
-MAKECMDGOALS := $(.DEFAULT_GOAL)
-endif
-
-define match_goals
-$(strip $(foreach goal,$(1),$(filter $(goal),$(MAKECMDGOALS))))
-endef
-
-# List of rules that involve building things
-BUILD_TARGETS := all bl1 bl2 bl2u bl31 bl32 certificates fip
-
-# Does the list of goals specified on the command line include a build target?
-ifneq ($(call match_goals,${BUILD_TARGETS}),)
-IS_ANYTHING_TO_BUILD := 1
-endif
-
+MAKE_DEP = -Wp,-MD,$(DEP) -MT $$@
 
 # MAKE_C builds a C source file and generates the dependency file
 #   $(1) = output directory
@@ -210,20 +193,14 @@ endif
 define MAKE_C
 
 $(eval OBJ := $(1)/$(patsubst %.c,%.o,$(notdir $(2))))
-$(eval PREREQUISITES := $(patsubst %.o,%.d,$(OBJ)))
+$(eval DEP := $(patsubst %.o,%.d,$(OBJ)))
 $(eval IMAGE := IMAGE_BL$(call uppercase,$(3)))
 
-$(OBJ): $(2)
+$(OBJ): $(2) | bl$(3)_dirs
 	@echo "  CC      $$<"
-	$$(Q)$$(CC) $$(TF_CFLAGS) $$(CFLAGS) -D$(IMAGE) -c $$< -o $$@
+	$$(Q)$$(CC) $$(TF_CFLAGS) $$(CFLAGS) -D$(IMAGE) $(MAKE_DEP) -c $$< -o $$@
 
-$(PREREQUISITES): $(2) | bl$(3)_dirs
-	@echo "  DEPS    $$@"
-	$$(Q)$$(CC) $$(TF_CFLAGS) $$(CFLAGS) -M -MT $(OBJ) -MF $$@ $$<
-
-ifdef IS_ANYTHING_TO_BUILD
--include $(PREREQUISITES)
-endif
+-include $(DEP)
 
 endef
 
@@ -235,20 +212,14 @@ endef
 define MAKE_S
 
 $(eval OBJ := $(1)/$(patsubst %.S,%.o,$(notdir $(2))))
-$(eval PREREQUISITES := $(patsubst %.o,%.d,$(OBJ)))
+$(eval DEP := $(patsubst %.o,%.d,$(OBJ)))
 $(eval IMAGE := IMAGE_BL$(call uppercase,$(3)))
 
-$(OBJ): $(2)
+$(OBJ): $(2) | bl$(3)_dirs
 	@echo "  AS      $$<"
-	$$(Q)$$(AS) $$(ASFLAGS) -D$(IMAGE) -c $$< -o $$@
-
-$(PREREQUISITES): $(2) | bl$(3)_dirs
-	@echo "  DEPS    $$@"
-	$$(Q)$$(AS) $$(ASFLAGS) -M -MT $(OBJ) -MF $$@ $$<
+	$$(Q)$$(AS) $$(ASFLAGS) -D$(IMAGE) $(MAKE_DEP) -c $$< -o $$@
 
-ifdef IS_ANYTHING_TO_BUILD
--include $(PREREQUISITES)
-endif
+-include $(DEP)
 
 endef
 
@@ -258,19 +229,13 @@ endef
 #   $(2) = input template
 define MAKE_LD
 
-$(eval PREREQUISITES := $(1).d)
+$(eval DEP := $(1).d)
 
-$(1): $(2)
+$(1): $(2) | $(dir ${1})
 	@echo "  PP      $$<"
-	$$(Q)$$(CPP) $$(CPPFLAGS) -P -D__ASSEMBLY__ -D__LINKER__ -o $$@ $$<
-
-$(PREREQUISITES): $(2) | $(dir ${1})
-	@echo "  DEPS    $$@"
-	$$(Q)$$(CPP) $$(CPPFLAGS) -D__ASSEMBLY__ -M -MT $(1) -MF $$@ $$<
+	$$(Q)$$(CPP) $$(CPPFLAGS) -P -D__ASSEMBLY__ -D__LINKER__ $(MAKE_DEP) -o $$@ $$<
 
-ifdef IS_ANYTHING_TO_BUILD
--include $(PREREQUISITES)
-endif
+-include $(DEP)
 
 endef