diff mbox series

[v2,1/5] kbuild: add test-{le,ge,lt,gt} macros

Message ID 20221123151828.509565-1-masahiroy@kernel.org (mailing list archive)
State New, archived
Headers show
Series [v2,1/5] kbuild: add test-{le,ge,lt,gt} macros | expand

Commit Message

Masahiro Yamada Nov. 23, 2022, 3:18 p.m. UTC 
Because GNU Make is only able to handle strings, it is very hard to
perform arighmetic in Makefiles.

When we compare two integers, we invokes shell. One example is in the
top Makefile:

  ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)

This is more expensive than using built-in functions since it forks a
process.

If we know the two have the same number of digits, we can do better.

This commit adds four macros, test-le, test-ge, test-lt, test-gt.

$(call test-lt, A, B) is evaluated to 'y' if A is less than B, or
empty otherwise. This will replace $(call shell test A -lt B).

Again, the limitation is that A and B must have the same number of
digits because these macros are based on $(sort ) function.

  $(call test-lt, 1, 9)    -->  y        (Works!)
  $(call test-lt, 10, 9)   -->  y        (Not work...)

To make the latter work, you need to add '0' prefix to align the number
of digits:

  $(call test-lt, 10, 09)  -->  empty    (Works!)

Actually, we can live with this limitation in many places. As for the
example above, we know $(CONFIG_LLD_VERSION) is 6-digits because the
minimal supported version of LLVM is 11.0.0.

So, the shell invocation can be replaced with more efficient code:

  ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)

Of course, this assumption will break when LLVM 100 is released, but it
will be far in the future.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

(no changes since v1)

 Makefile               |  2 +-
 arch/riscv/Makefile    |  2 +-
 arch/x86/Makefile      |  2 +-
 scripts/Kbuild.include | 10 ++++++++++
 4 files changed, 13 insertions(+), 3 deletions(-)

Comments

Nicolas Schier Nov. 23, 2022, 8:05 p.m. UTC | #1 
On Thu 24 Nov 2022 00:18:24 GMT, Masahiro Yamada wrote:
> Because GNU Make is only able to handle strings, it is very hard to
> perform arighmetic in Makefiles.
> 
> When we compare two integers, we invokes shell. One example is in the
> top Makefile:
> 
>   ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
> 
> This is more expensive than using built-in functions since it forks a
> process.
> 
> If we know the two have the same number of digits, we can do better.
> 
> This commit adds four macros, test-le, test-ge, test-lt, test-gt.
> 
> $(call test-lt, A, B) is evaluated to 'y' if A is less than B, or
> empty otherwise. This will replace $(call shell test A -lt B).
> 
> Again, the limitation is that A and B must have the same number of
> digits because these macros are based on $(sort ) function.
> 
>   $(call test-lt, 1, 9)    -->  y        (Works!)
>   $(call test-lt, 10, 9)   -->  y        (Not work...)
> 
> To make the latter work, you need to add '0' prefix to align the number
> of digits:
> 
>   $(call test-lt, 10, 09)  -->  empty    (Works!)
> 
> Actually, we can live with this limitation in many places. As for the
> example above, we know $(CONFIG_LLD_VERSION) is 6-digits because the
> minimal supported version of LLVM is 11.0.0.
> 
> So, the shell invocation can be replaced with more efficient code:
> 
>   ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)
> 
> Of course, this assumption will break when LLVM 100 is released, but it
> will be far in the future.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
> (no changes since v1)
> 
>  Makefile               |  2 +-
>  arch/riscv/Makefile    |  2 +-
>  arch/x86/Makefile      |  2 +-
>  scripts/Kbuild.include | 10 ++++++++++
>  4 files changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 6f846b1f2618..eb80332f7b51 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -986,7 +986,7 @@ KBUILD_LDFLAGS += -mllvm -import-instr-limit=5
>  # Check for frame size exceeding threshold during prolog/epilog insertion
>  # when using lld < 13.0.0.
>  ifneq ($(CONFIG_FRAME_WARN),0)
> -ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
> +ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)
>  KBUILD_LDFLAGS	+= -plugin-opt=-warn-stack-size=$(CONFIG_FRAME_WARN)
>  endif
>  endif
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index 0d13b597cb55..faf2c2177094 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -37,7 +37,7 @@ else
>  endif
>  
>  ifeq ($(CONFIG_LD_IS_LLD),y)
> -ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 150000; echo $$?),0)
> +ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 150000),y)
>  	KBUILD_CFLAGS += -mno-relax
>  	KBUILD_AFLAGS += -mno-relax
>  ifndef CONFIG_AS_IS_LLVM
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index 415a5d138de4..e72c7a49cd59 100644
> --- a/arch/x86/Makefile
> +++ b/arch/x86/Makefile
> @@ -211,7 +211,7 @@ endif
>  KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE)
>  
>  ifdef CONFIG_LTO_CLANG
> -ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
> +ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)
>  KBUILD_LDFLAGS	+= -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8)
>  endif
>  endif
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index cbe28744637b..9996f34327cb 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -11,6 +11,16 @@ space   := $(empty) $(empty)
>  space_escape := _-_SPACE_-_
>  pound := \#
>  
> +###
> +# Comparison macros.
> +# Usage: $(call test-le, A, B)
> +# works like shell's "test A -le B", but A and B must have the same number of
> +# digits since it is just ASCII sort.
> +test-le = $(if $(filter $1, $(firstword $(sort $1 $2))),y)
> +test-ge = $(call test-le, $2, $1)
> +test-lt = $(if $(filter-out $2, $(firstword $(sort $1 $2))),y)
> +test-gt = $(call test-lt, $2, $1)
> +

I like that whole patch set, thanks!  A cherry on the cake would be a 
sanity check for equal length of A and B ...

Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

>  ###
>  # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
>  dot-target = $(dir $@).$(notdir $@)
> -- 
> 2.34.1
Palmer Dabbelt Dec. 2, 2022, 5:56 p.m. UTC | #2 
On Wed, 23 Nov 2022 07:18:24 PST (-0800), masahiroy@kernel.org wrote:
> Because GNU Make is only able to handle strings, it is very hard to
> perform arighmetic in Makefiles.
>
> When we compare two integers, we invokes shell. One example is in the
> top Makefile:
>
>   ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
>
> This is more expensive than using built-in functions since it forks a
> process.
>
> If we know the two have the same number of digits, we can do better.
>
> This commit adds four macros, test-le, test-ge, test-lt, test-gt.
>
> $(call test-lt, A, B) is evaluated to 'y' if A is less than B, or
> empty otherwise. This will replace $(call shell test A -lt B).
>
> Again, the limitation is that A and B must have the same number of
> digits because these macros are based on $(sort ) function.
>
>   $(call test-lt, 1, 9)    -->  y        (Works!)
>   $(call test-lt, 10, 9)   -->  y        (Not work...)
>
> To make the latter work, you need to add '0' prefix to align the number
> of digits:
>
>   $(call test-lt, 10, 09)  -->  empty    (Works!)
>
> Actually, we can live with this limitation in many places. As for the
> example above, we know $(CONFIG_LLD_VERSION) is 6-digits because the
> minimal supported version of LLVM is 11.0.0.
>
> So, the shell invocation can be replaced with more efficient code:
>
>   ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)
>
> Of course, this assumption will break when LLVM 100 is released, but it
> will be far in the future.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>
> (no changes since v1)
>
>  Makefile               |  2 +-
>  arch/riscv/Makefile    |  2 +-
>  arch/x86/Makefile      |  2 +-
>  scripts/Kbuild.include | 10 ++++++++++
>  4 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 6f846b1f2618..eb80332f7b51 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -986,7 +986,7 @@ KBUILD_LDFLAGS += -mllvm -import-instr-limit=5
>  # Check for frame size exceeding threshold during prolog/epilog insertion
>  # when using lld < 13.0.0.
>  ifneq ($(CONFIG_FRAME_WARN),0)
> -ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
> +ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)
>  KBUILD_LDFLAGS	+= -plugin-opt=-warn-stack-size=$(CONFIG_FRAME_WARN)
>  endif
>  endif
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index 0d13b597cb55..faf2c2177094 100644
> --- a/arch/riscv/Makefile
> +++ b/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

Acked-by: Palmer Dabbelt <palmer@rivosinc.com> # RISC-V

> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index 415a5d138de4..e72c7a49cd59 100644
> --- a/arch/x86/Makefile
> +++ b/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
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index cbe28744637b..9996f34327cb 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -11,6 +11,16 @@ space   := $(empty) $(empty)
>  space_escape := _-_SPACE_-_
>  pound := \#
>
> +###
> +# Comparison macros.
> +# Usage: $(call test-le, A, B)
> +# works like shell's "test A -le B", but A and B must have the same number of
> +# digits since it is just ASCII sort.
> +test-le = $(if $(filter $1, $(firstword $(sort $1 $2))),y)
> +test-ge = $(call test-le, $2, $1)
> +test-lt = $(if $(filter-out $2, $(firstword $(sort $1 $2))),y)
> +test-gt = $(call test-lt, $2, $1)
> +
>  ###
>  # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
>  dot-target = $(dir $@).$(notdir $@)
Masahiro Yamada Dec. 8, 2022, 1:42 a.m. UTC | #3 
On Thu, Nov 24, 2022 at 12:19 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Because GNU Make is only able to handle strings, it is very hard to
> perform arighmetic in Makefiles.





I terribly missed that GNU Make 4.4
introduced the $(intcmp ...) function.

https://www.gnu.org/software/make/manual/make.html#Conditional-Functions


I am thinking if we can do better by using it.















>
> When we compare two integers, we invokes shell. One example is in the
> top Makefile:
>
>   ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
>
> This is more expensive than using built-in functions since it forks a
> process.
>
> If we know the two have the same number of digits, we can do better.
>
> This commit adds four macros, test-le, test-ge, test-lt, test-gt.
>
> $(call test-lt, A, B) is evaluated to 'y' if A is less than B, or
> empty otherwise. This will replace $(call shell test A -lt B).
>
> Again, the limitation is that A and B must have the same number of
> digits because these macros are based on $(sort ) function.
>
>   $(call test-lt, 1, 9)    -->  y        (Works!)
>   $(call test-lt, 10, 9)   -->  y        (Not work...)
>
> To make the latter work, you need to add '0' prefix to align the number
> of digits:
>
>   $(call test-lt, 10, 09)  -->  empty    (Works!)
>
> Actually, we can live with this limitation in many places. As for the
> example above, we know $(CONFIG_LLD_VERSION) is 6-digits because the
> minimal supported version of LLVM is 11.0.0.
>
> So, the shell invocation can be replaced with more efficient code:
>
>   ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)
>
> Of course, this assumption will break when LLVM 100 is released, but it
> will be far in the future.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>
> (no changes since v1)
>
>  Makefile               |  2 +-
>  arch/riscv/Makefile    |  2 +-
>  arch/x86/Makefile      |  2 +-
>  scripts/Kbuild.include | 10 ++++++++++
>  4 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 6f846b1f2618..eb80332f7b51 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -986,7 +986,7 @@ KBUILD_LDFLAGS += -mllvm -import-instr-limit=5
>  # Check for frame size exceeding threshold during prolog/epilog insertion
>  # when using lld < 13.0.0.
>  ifneq ($(CONFIG_FRAME_WARN),0)
> -ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
> +ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)
>  KBUILD_LDFLAGS += -plugin-opt=-warn-stack-size=$(CONFIG_FRAME_WARN)
>  endif
>  endif
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index 0d13b597cb55..faf2c2177094 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -37,7 +37,7 @@ else
>  endif
>
>  ifeq ($(CONFIG_LD_IS_LLD),y)
> -ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 150000; echo $$?),0)
> +ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 150000),y)
>         KBUILD_CFLAGS += -mno-relax
>         KBUILD_AFLAGS += -mno-relax
>  ifndef CONFIG_AS_IS_LLVM
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index 415a5d138de4..e72c7a49cd59 100644
> --- a/arch/x86/Makefile
> +++ b/arch/x86/Makefile
> @@ -211,7 +211,7 @@ endif
>  KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE)
>
>  ifdef CONFIG_LTO_CLANG
> -ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
> +ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 130000),y)
>  KBUILD_LDFLAGS += -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8)
>  endif
>  endif
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index cbe28744637b..9996f34327cb 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -11,6 +11,16 @@ space   := $(empty) $(empty)
>  space_escape := _-_SPACE_-_
>  pound := \#
>
> +###
> +# Comparison macros.
> +# Usage: $(call test-le, A, B)
> +# works like shell's "test A -le B", but A and B must have the same number of
> +# digits since it is just ASCII sort.
> +test-le = $(if $(filter $1, $(firstword $(sort $1 $2))),y)
> +test-ge = $(call test-le, $2, $1)
> +test-lt = $(if $(filter-out $2, $(firstword $(sort $1 $2))),y)
> +test-gt = $(call test-lt, $2, $1)
> +
>  ###
>  # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
>  dot-target = $(dir $@).$(notdir $@)
> --
> 2.34.1
>
diff mbox series

Patch

diff --git a/Makefile b/Makefile
index 6f846b1f2618..eb80332f7b51 100644
--- a/Makefile
+++ b/Makefile
@@ -986,7 +986,7 @@  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
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 0d13b597cb55..faf2c2177094 100644
--- a/arch/riscv/Makefile
+++ b/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, $(CONFIG_LLD_VERSION), 150000),y)
 	KBUILD_CFLAGS += -mno-relax
 	KBUILD_AFLAGS += -mno-relax
 ifndef CONFIG_AS_IS_LLVM
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 415a5d138de4..e72c7a49cd59 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -211,7 +211,7 @@  endif
 KBUILD_LDFLAGS += -m elf_$(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
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index cbe28744637b..9996f34327cb 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -11,6 +11,16 @@  space   := $(empty) $(empty)
 space_escape := _-_SPACE_-_
 pound := \#
 
+###
+# Comparison macros.
+# Usage: $(call test-le, A, B)
+# works like shell's "test A -le B", but A and B must have the same number of
+# digits since it is just ASCII sort.
+test-le = $(if $(filter $1, $(firstword $(sort $1 $2))),y)
+test-ge = $(call test-le, $2, $1)
+test-lt = $(if $(filter-out $2, $(firstword $(sort $1 $2))),y)
+test-gt = $(call test-lt, $2, $1)
+
 ###
 # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
 dot-target = $(dir $@).$(notdir $@)