Re: [stalld v2 2/6] Makefile: Improve compiler flag detection for -fcf-protection

[Clark Williams <williams@redhat.com>]

On Mon, Nov 10, 2025 at 10:22:37AM -0300, Wander Lairson Costa wrote:
> The previous method of detecting support for -fcf-protection relied on
> a minimum GCC version check, which was not always accurate and could
> fail on different architectures or compiler toolchains.
> 
> This commit replaces the version check with a more robust method that
> directly tests if the compiler supports the -fcf-protection flag. This
> ensures better portability and avoids compilation errors on systems
> where the flag is not available.
> 
> This change mirrors the recently added detection logic for the
> -mno-omit-leaf-frame-pointer flag.
> 
> Signed-off-by: Wander Lairson Costa <wander@redhat.com>
> Cc: Derek Barbosa <debarbos@redhat.com>
> Cc: John Kacur <jkacur@redhat.com>
> Cc: Juri Lelli <juri.lelli@redhat.com>
> Cc: Chunsheng Luo <luochunsheng@ustc.edu>
> ---
>  Makefile | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index d605e60..23e786d 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -20,17 +20,14 @@ IS_MINVER := $(intcmp $(GCC_VER), $(MIN_GCC_VER), false, true, true)
>  $(info IS_MINVER=$(IS_MINVER))
>  
>  USE_BPF := 1
> -FCF_PROTECTION := -fcf-protection
>  MTUNE	:= -mtune=generic
>  M64	:= -m64
>  
>  ifeq ($(ARCH),aarch64)
> -FCF_PROTECTION := "-fcf-protection=none"
>  M64	:=
>  endif
>  ifeq ($(ARCH),i686)
>  USE_BPF := 0
> -FCF_PROTECTION := "-fcf-protection=branch"
>  endif
>  ifeq ($(ARCH),s390x)
>  MTUNE := -mtune=z13
> @@ -43,23 +40,23 @@ ifeq ($(ARCH),powerpc)
>  USE_BPF := 0
>  MTUNE := -mtune=powerpc
>  endif
> -ifeq ($(strip $(IS_MINVER)), false)
> -FCF_PROTECTION := 
> -endif
> -
> -
> -$(info USE_BPF=$(USE_BPF))
> -$(info FCF_PROTECTION=$(FCF_PROTECTION))
> -$(info MTUNE=$(MTUNE))
>  
>  DEBUG	?=	0
>  
>  INSTALL	=	install
>  CC	:=	gcc
> +
> +# Test if compiler supports -fcf-protection
> +FCF_PROTECTION := $(shell echo 'int main(void){return 0;}' | \
> +		$(CC) -x c -fcf-protection - \
> +		-o /dev/null 2>/dev/null && \
> +		echo '-fcf-protection')
> +
>  FOPTS	:=	-flto=auto -ffat-lto-objects -fexceptions -fstack-protector-strong \
>  		-fasynchronous-unwind-tables -fstack-clash-protection -fno-omit-frame-pointer \
>  		$(strip $(FCF_PROTECTION)) -fpie
>  
> +
>  # Test if compiler supports -mno-omit-leaf-frame-pointer
>  OMIT_LEAF_FP := $(shell echo 'int main(void){return 0;}' | \
>  		$(CC) -x c -mno-omit-leaf-frame-pointer - \
> @@ -74,6 +71,10 @@ DEFS	:=	-DUSE_BPF=$(USE_BPF) -D_FORTIFY_SOURCE=3 -D_GLIBCXX_ASSERTIONS -DDEBUG_S
>  
>  CFLAGS	:=      -DVERSION=\"$(VERSION)\" $(FOPTS) $(MOPTS) $(WOPTS) $(DEFS)
>  
> +$(info USE_BPF=$(USE_BPF))
> +$(info FCF_PROTECTION=$(FCF_PROTECTION))
> +$(info MTUNE=$(MTUNE))
> +
>  ifeq ($(DEBUG),0)
>  CFLAGS	+=	-g -O2
>  else
> -- 
> 2.51.1
> 
Signed-off-by: Clark Williams <williams@redhat.com>
-- 
The United States Coast Guard
Ruining Natural Selection since 1790