From db07562aeac77923370bff4733d8b0e09cbc93c4 Mon Sep 17 00:00:00 2001 From: Nick Desaulniers Date: Fri, 5 Feb 2021 14:01:25 -0800 Subject: [PATCH] Makefile: reuse CC_VERSION_TEXT I noticed we're invoking $(CC) via $(shell) more than once to check the version. Let's reuse the first string captured in $CC_VERSION_TEXT. Signed-off-by: Nick Desaulniers [masahiro.yamada: CC_VERSION_TEXT is assigned by = instead of :=, so this $(shell ) is evaluated multiple times anyway. The number of $(CC) invocations will be still the same. Replacing 'grep' with the built-in $(findstring ) will give real performance benefit.] Signed-off-by: Masahiro Yamada --- Makefile | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/Makefile b/Makefile index 1fdd44fe1659..6c3a2064072d 100644 --- a/Makefile +++ b/Makefile @@ -557,7 +557,13 @@ ifdef building_out_of_srctree { echo "# this is build directory, ignore it"; echo "*"; } > .gitignore endif -ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),) +# The expansion should be delayed until arch/$(SRCARCH)/Makefile is included. +# Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile. +# CC_VERSION_TEXT is referenced from Kconfig (so it needs export), +# and from include/config/auto.conf.cmd to detect the compiler upgrade. +CC_VERSION_TEXT = $(shell $(CC) --version 2>/dev/null | head -n 1) + +ifneq ($(findstring clang,$(CC_VERSION_TEXT)),) ifneq ($(CROSS_COMPILE),) CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) @@ -576,12 +582,6 @@ KBUILD_AFLAGS += $(CLANG_FLAGS) export CLANG_FLAGS endif -# The expansion should be delayed until arch/$(SRCARCH)/Makefile is included. -# Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile. -# CC_VERSION_TEXT is referenced from Kconfig (so it needs export), -# and from include/config/auto.conf.cmd to detect the compiler upgrade. -CC_VERSION_TEXT = $(shell $(CC) --version 2>/dev/null | head -n 1) - ifdef config-build # =========================================================================== # *config targets only - make sure prerequisites are updated, and descend