[PATCH 1/2] kbuild: include scripts/Makefile.* only when relevant CONFIG is enabled

From: Masahiro Yamada
Date: Sat Aug 01 2020 - 11:02:36 EST


Currently, the top Makefile includes all of scripts/Makefile.<feature>
even if the associated CONFIG option is disabled.

Do not include unneeded Makefiles in order to slightly optimize the
parse stage.

Include $(include-y), and ignore $(include-).

Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
---

Makefile | 16 +++++++++-------
scripts/Makefile.kcov | 4 ----
scripts/Makefile.kcsan | 4 ----
scripts/Makefile.ubsan | 3 ---
4 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/Makefile b/Makefile
index ebf4d3ce492c..483456d5dd3e 100644
--- a/Makefile
+++ b/Makefile
@@ -745,9 +745,6 @@ endif
KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0)
KBUILD_CFLAGS += $(call cc-option,-fno-allow-store-data-races)

-include scripts/Makefile.kcov
-include scripts/Makefile.gcc-plugins
-
ifdef CONFIG_READABLE_ASM
# Disable optimizations that make assembler listings hard to read.
# reorder blocks reorders the control in the function
@@ -948,10 +945,15 @@ ifdef CONFIG_RETPOLINE
KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
endif

-include scripts/Makefile.kasan
-include scripts/Makefile.extrawarn
-include scripts/Makefile.ubsan
-include scripts/Makefile.kcsan
+# include additional Makefiles when needed
+include-y := scripts/Makefile.extrawarn
+include-$(CONFIG_KASAN) += scripts/Makefile.kasan
+include-$(CONFIG_KCSAN) += scripts/Makefile.kcsan
+include-$(CONFIG_UBSAN) += scripts/Makefile.ubsan
+include-$(CONFIG_KCOV) += scripts/Makefile.kcov
+include-$(CONFIG_GCC_PLUGINS) += scripts/Makefile.gcc-plugins
+
+include $(addprefix $(srctree)/, $(include-y))

# Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
KBUILD_CPPFLAGS += $(KCPPFLAGS)
diff --git a/scripts/Makefile.kcov b/scripts/Makefile.kcov
index 52b113302443..67e8cfe3474b 100644
--- a/scripts/Makefile.kcov
+++ b/scripts/Makefile.kcov
@@ -1,10 +1,6 @@
# SPDX-License-Identifier: GPL-2.0-only
-ifdef CONFIG_KCOV
-
kcov-flags-$(CONFIG_CC_HAS_SANCOV_TRACE_PC) += -fsanitize-coverage=trace-pc
kcov-flags-$(CONFIG_KCOV_ENABLE_COMPARISONS) += -fsanitize-coverage=trace-cmp
kcov-flags-$(CONFIG_GCC_PLUGIN_SANCOV) += -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so

export CFLAGS_KCOV := $(kcov-flags-y)
-
-endif
diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
index bd4da1af5953..2b0743e6566e 100644
--- a/scripts/Makefile.kcsan
+++ b/scripts/Makefile.kcsan
@@ -1,6 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
-ifdef CONFIG_KCSAN
-
# GCC and Clang accept backend options differently. Do not wrap in cc-option,
# because Clang accepts "--param" even if it is unused.
ifdef CONFIG_CC_IS_CLANG
@@ -15,5 +13,3 @@ CFLAGS_KCSAN := -fsanitize=thread \
$(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls) \
$(call cc-option,$(call cc-param,tsan-instrument-read-before-write=1)) \
$(call cc-param,tsan-distinguish-volatile=1)
-
-endif # CONFIG_KCSAN
diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan
index 5b15bc425ec9..27348029b2b8 100644
--- a/scripts/Makefile.ubsan
+++ b/scripts/Makefile.ubsan
@@ -1,6 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
-ifdef CONFIG_UBSAN
-
ifdef CONFIG_UBSAN_ALIGNMENT
CFLAGS_UBSAN += $(call cc-option, -fsanitize=alignment)
endif
@@ -26,4 +24,3 @@ endif
# -fsanitize=* options makes GCC less smart than usual and
# increase number of 'maybe-uninitialized false-positives
CFLAGS_UBSAN += $(call cc-option, -Wno-maybe-uninitialized)
-endif
--
2.25.1