Re: [Qemu-devel] [RFC][PATCH v2 4/4] configure: add CONFIG_QEMU_LDST_OPTIMIZATION for TCG qemu_ld/st optimization

["Andreas Färber" <afaerber@suse.de>]

Am 05.07.2012 15:23, schrieb Yeongkyoon Lee:
> Add an option "--enable-ldst-optimization" to enable CONFIG_QEMU_LDST_OPTIMIZATION macro for TCG qemu_ld/st optimization. It only works with CONFIG_SOFTMMU and doesn't work with CONFIG_TCG_PASS_AREG0.
> 
> Signed-off-by: Yeongkyoon Lee <yeongkyoon.lee@samsung.com>
> ---
>  configure |   15 +++++++++++++++
>  1 files changed, 15 insertions(+), 0 deletions(-)
> 
> diff --git a/configure b/configure
> index 9f071b7..2b364cc 100755
> --- a/configure
> +++ b/configure
[...]
> @@ -3463,6 +3466,11 @@ echo "EXESUF=$EXESUF" >> $config_host_mak
>  echo "LIBS_QGA+=$libs_qga" >> $config_host_mak
>  echo "POD2MAN=$POD2MAN" >> $config_host_mak
>  
> +if [ "$ldst_optimization" = "yes" -a "$cpu" != "i386" -a "$cpu" != "x86_64" ] ; then
> +  echo "ERROR: qemu_ld/st optimization is only available on i386 or x86_64 hosts"
> +  exit 1
> +fi
[snip]

I assume that Samsung is interested in optimizing the Exynos emulation.
I think there was already a patchset posted converting target-arm to
CONFIG_PASS_TCG_AREG0, only with some slowdowns to be investigated...
What is the obstacle for supporting AREG0 mode in your optimization?

Regards,
Andreas

> +
>  # generate list of library paths for linker script
>  
>  $ld --verbose -v 2> /dev/null | grep SEARCH_DIR > ${config_host_ld}
> @@ -3696,11 +3704,18 @@ fi
>  symlink "$source_path/Makefile.target" "$target_dir/Makefile"
>  
>  
> +target_ldst_optimization="$ldst_optimization"
> +
>  case "$target_arch2" in
>    alpha | sparc* | xtensa* | ppc*)
>      echo "CONFIG_TCG_PASS_AREG0=y" >> $config_target_mak
> +    # qemu_ld/st optimization is not available with CONFIG_TCG_PASS_AREG0
> +    target_ldst_optimization="no"
>    ;;
>  esac
> +if [ "$target_ldst_optimization" = "yes" -a "$target_softmmu" = "yes" ] ; then
> +    echo "CONFIG_QEMU_LDST_OPTIMIZATION=y" >> $config_target_mak
> +fi
>  
>  echo "TARGET_SHORT_ALIGNMENT=$target_short_alignment" >> $config_target_mak
>  echo "TARGET_INT_ALIGNMENT=$target_int_alignment" >> $config_target_mak

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