kbuild: add test-{ge,gt,le,lt} macros

GNU Make 4.4 introduced $(intcmp ...), which is useful to compare two
integers without forking a new process.

Add test-{ge,gt,le,lt} macros, which work more efficiently with GNU
Make >= 4.4. For older Make versions, they fall back to the 'test'
shell command.

The first two parameters to $(intcmp ...) must not be empty. To avoid
the syntax error, I appended '0' to them. Fortunately, '00' is treated
as '0'. This is needed because CONFIG options may expand to an empty
string when the kernel configuration is not included.

Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Palmer Dabbelt <[email protected]> # RISC-V
Reviewed-by: Nathan Chancellor <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>

Makefile

@@ -994,7 +994,7 @@ KBUILD_LDFLAGS += -mllvm -import-instr-limit=5
 # Check for frame size exceeding threshold during prolog/epilog insertion
 # when using lld < 13.0.0.
 ifneq ($(CONFIG_FRAME_WARN),0)
-ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
+ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)
 KBUILD_LDFLAGS	+= -plugin-opt=-warn-stack-size=$(CONFIG_FRAME_WARN)
 endif
 endif

arch/riscv/Makefile

@@ -37,7 +37,7 @@ else
 endif
 
 ifeq ($(CONFIG_LD_IS_LLD),y)
-ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 150000; echo $$?),0)
+ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 150000),y)
 	KBUILD_CFLAGS += -mno-relax
 	KBUILD_AFLAGS += -mno-relax
 ifndef CONFIG_AS_IS_LLVM

arch/x86/Makefile

@@ -211,7 +211,7 @@ endif
 KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE)
 
 ifdef CONFIG_LTO_CLANG
-ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
+ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)
 KBUILD_LDFLAGS	+= -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8)
 endif
 endif

scripts/Kbuild.include

@@ -11,6 +11,22 @@ space   := $(empty) $(empty)
 space_escape := _-_SPACE_-_
 pound := \#
 
+###
+# Comparison macros.
+# Usage: $(call test-lt, $(CONFIG_LLD_VERSION), 150000)
+#
+# Use $(intcmp ...) if supported. (Make >= 4.4)
+# Otherwise, fall back to the 'test' shell command.
+ifeq ($(intcmp 1,0,,,y),y)
+test-ge = $(intcmp $(strip $1)0, $(strip $2)0,,y,y)
+test-gt = $(intcmp $(strip $1)0, $(strip $2)0,,,y)
+else
+test-ge = $(shell test $(strip $1)0 -ge $(strip $2)0 && echo y)
+test-gt = $(shell test $(strip $1)0 -gt $(strip $2)0 && echo y)
+endif
+test-le = $(call test-ge, $2, $1)
+test-lt = $(call test-gt, $2, $1)
+
 ###
 # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
 dot-target = $(dir $@).$(notdir $@)

scripts/Makefile.compiler

@@ -63,11 +63,11 @@ cc-disable-warning = $(call try-run,\
 
 # gcc-min-version
 # Usage: cflags-$(call gcc-min-version, 70100) += -foo
-gcc-min-version = $(shell [ $(CONFIG_GCC_VERSION)0 -ge $(1)0 ] && echo y)
+gcc-min-version = $(call test-ge, $(CONFIG_GCC_VERSION), $1)
 
 # clang-min-version
 # Usage: cflags-$(call clang-min-version, 110000) += -foo
-clang-min-version = $(shell [ $(CONFIG_CLANG_VERSION)0 -ge $(1)0 ] && echo y)
+clang-min-version = $(call test-ge, $(CONFIG_CLANG_VERSION), $1)
 
 # ld-option
 # Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)