Evaluate LDFLAGS_BUILD_ID (which involves invoking the compiler) only
once instead of over and over.
This provides a ~20% reduction in null build time with x86 allnoconfig:
$ make allnoconfig && make -j8
$ perf stat -r5 -e sched:sched_process_exec make -j8
- 2 119 sched:sched_process_exec
+ 1 878 sched:sched_process_exec
- 1,
238817018 seconds time elapsed
+ 0,
971020553 seconds time elapsed
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
KBUILD_CFLAGS += $(ARCH_CFLAGS) $(KCFLAGS)
# Use --build-id when available.
-LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\
+LDFLAGS_BUILD_ID := $(patsubst -Wl$(comma)%,%,\
$(call cc-ldoption, -Wl$(comma)--build-id,))
KBUILD_LDFLAGS_MODULE += $(LDFLAGS_BUILD_ID)
LDFLAGS_vmlinux += $(LDFLAGS_BUILD_ID)