On Wed, 2023-08-30 at 09:58 +0800, Yang Yujie wrote:
> LoongArch processors may not support memory accesses without natural
> alignments. Building libraries with -mstrict-align may help with
> toolchain binary compatiblity and performance on these implementations
> (e.g. Loongson 2K1000LA).
>
> No significant performance degredation is observed on current mainstream
> LoongArch processors when the option is enabled.
>
> gcc/ChangeLog:
>
> * config.gcc: use -mstrict-align for building libraries
> if --with-strict-align-lib is given.
Isn't this equivalent to --with-default-multilib=mno-strict-align now?
And I still believe the easiest way for 2K1000LA is adding -march=la264
support so the user can simply configure with --with-arch=la264.
> ---
> gcc/config.gcc | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/config.gcc b/gcc/config.gcc
> index 4fae672a3b7..ed70fa63268 100644
> --- a/gcc/config.gcc
> +++ b/gcc/config.gcc
> @@ -4892,7 +4892,7 @@ case "${target}" in
> ;;
>
> loongarch*-*)
> - supported_defaults="abi arch tune fpu simd multilib-
> default"
> + supported_defaults="abi arch tune fpu simd multilib-
> default strict-align-lib"
>
> # Local variables
> unset \
> @@ -5089,6 +5089,17 @@ case "${target}" in
> ;;
> esac
>
> + # Build libraries with -mstrict-align if --with-
> strict-align-lib is given.
> + case ${with_strict_align_lib} in
> + yes) strict_align_opt="/mstrict-align" ;;
> + ""|no) ;;
> + *)
> + echo "Unknown option: --with-strict-align-
> lib=${with_strict_align_lib}" 1>&2
> + exit 1
> + ;;
> + esac
> +
> +
> # Handle --with-multilib-default
> if echo "${with_multilib_default}" \
> | grep -E -e '[[:space:]]' -e '//' -e '/$' -e '^/' >
> /dev/null 2>&1; then
> @@ -5250,6 +5261,9 @@ case "${target}" in
> ;;
> esac
>
> + # Use mstrict-align for building libraries if
> --with-strict-align-lib is given.
> + loongarch_multilib_list_make="${loongarch_mult
> ilib_list_make}${strict_align_opt}"
> +
> # Check for repeated configuration of the same
> multilib variant.
> if echo "${elem_abi_base}/${elem_abi_ext}" \
> | grep -E "^(${all_abis%|})$" >/dev/null
> 2>&1; then
--
Xi Ruoyao <xry...@xry111.site>
School of Aerospace Science and Technology, Xidian University
