Re: [Buildroot] [PATCH v2 1/4] package/Makefile.in: use gcc wrappers for binutils tools

["Yann E. MORIN" <yann.morin.1998@free.fr>]

Norbert, All,

On 2020-10-18 00:17 +0200, Norbert Lange spake thusly:
> This will use gcc-ar, gcc-nm and gcc-ranlib instead of the
> normal binutils tools. The difference is that with the
> wrappers, gcc plugins will be automatically picked up.
> 
> gcc 4.7 introduced these wrappers, to detect the prefix and
> keep gcc specifics out of Makefile.in, a new variable
> BR2_TOOLCHAIN_BUTILS_PREFIX will be used to carry the
> prefix on supported versions.
> 
> Note that binutils added some automatic loading with the
> 'bfd-plugins' directory (somewhere around 2.28), but
> the first implementation had issues, and generally depends on
> correctly setup symlinks (often broken, may point to some
> other gcc's library). The wrappers always work painless.
> 
> The original motivation (now ~2 years in use) was to add
> "-flto -ffat-lto-objects" to both BR2_TARGET_OPTIMIZATION and
> BR2_TARGET_LDFLAGS, and have target binaries lto optimized.
> 
> Not all packages will compile with this option, further work
> could white/blacklist packages (adding -fno-lto to the
> options).
> 
> Signed-off-by: Norbert Lange <nolange79@gmail.com>
> ---
> v1->v2:
> *   support older gcc versions missing those wrappers
> ---
>  package/Makefile.in | 6 +++---
>  toolchain/Config.in | 7 +++++++
>  2 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/package/Makefile.in b/package/Makefile.in
> index 51f5cbce4f..665edec539 100644
> --- a/package/Makefile.in
> +++ b/package/Makefile.in
> @@ -198,15 +198,15 @@ TARGET_CROSS = $(HOST_DIR)/bin/$(TOOLCHAIN_EXTERNAL_PREFIX)-
>  endif
>  
>  # Define TARGET_xx variables for all common binutils/gcc
> -TARGET_AR       = $(TARGET_CROSS)ar
> +TARGET_AR       = $(TARGET_CROSS)$(call qstrip,$(BR2_TOOLCHAIN_BUTILS_PREFIX))ar
>  TARGET_AS       = $(TARGET_CROSS)as
>  TARGET_CC       = $(TARGET_CROSS)gcc
>  TARGET_CPP      = $(TARGET_CROSS)cpp
>  TARGET_CXX      = $(TARGET_CROSS)g++
>  TARGET_FC       = $(TARGET_CROSS)gfortran
>  TARGET_LD       = $(TARGET_CROSS)ld
> -TARGET_NM       = $(TARGET_CROSS)nm
> -TARGET_RANLIB   = $(TARGET_CROSS)ranlib
> +TARGET_NM       = $(TARGET_CROSS)$(call qstrip,$(BR2_TOOLCHAIN_BUTILS_PREFIX))nm
> +TARGET_RANLIB   = $(TARGET_CROSS)$(call qstrip,$(BR2_TOOLCHAIN_BUTILS_PREFIX))ranlib
>  TARGET_READELF  = $(TARGET_CROSS)readelf
>  TARGET_OBJCOPY  = $(TARGET_CROSS)objcopy
>  TARGET_OBJDUMP  = $(TARGET_CROSS)objdump
> diff --git a/toolchain/Config.in b/toolchain/Config.in
> index db2ab0f059..7a2becc09a 100644
> --- a/toolchain/Config.in
> +++ b/toolchain/Config.in
> @@ -732,4 +732,11 @@ config BR2_TOOLCHAIN_HAS_LIBQUADMATH
>  	bool
>  	default y if BR2_i386 || BR2_x86_64
>  
> +# gcc ships with wrappers that will automatically pass arguments
> +# to the binutils tools.
> +# So far, those are paths to necessary linker plugins
> +config BR2_TOOLCHAIN_BUTILS_PREFIX
> +	string
> +	default "gcc-" if BR2_TOOLCHAIN_GCC_AT_LEAST_4_7

There was no need for a Kconfig option, so I moved that to the Makefile
side.

Applied to master, thanks.

Regards,
Yann E. MORIN.

>  endmenu
> -- 
> 2.28.0

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