Re: [PATCH v2] C-SKY: Strip hard float abi from hard float feature.

[Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>]

On 26/01/23 23:06, Xianmiao Qu via Libc-alpha wrote:
> The hard float abi and hard float are different,
>   Hard float abi: Use float register to pass float type arguments.
>   Hard float: Enable the hard float ISA feature.> So the with_fp_cond cannot represent these two features. When
> -mfloat-abi=softfp, the float abi is soft and hard float is enabled.
> So add 'with_hard_float_abi' in preconfigure and define 'CSKY_HARD_FLOAT_ABI'
> if float abi is hard, and use 'CSKY_HARD_FLOAT_ABI' to determine
> dynamic linker because it is what determines compatibility.
> And with_fp_cond is still needed to tell glibc whether to enable
> hard floating feature.
> In addition, use AC_TRY_COMMAND to test gcc to ensure compatibility
> between different versions of gcc. The original way has a problem
> that __CSKY_HARD_FLOAT_FPU_SF__ means the target only has single
> hard float-points ISA, so it's not defined in CPUs like ck810f.
> ---
>  config.h.in                                 |  5 ++-
>  sysdeps/csky/preconfigure                   | 47 ++++++++++++---------
>  sysdeps/csky/preconfigure.ac                | 39 +++++++++--------
>  sysdeps/unix/sysv/linux/csky/shlib-versions |  4 +-
>  4 files changed, 52 insertions(+), 43 deletions(-)
>  mode change 100644 => 100755 sysdeps/csky/preconfigure
> 
> diff --git a/config.h.in b/config.h.in
> index 43d32518ab..09730d9d52 100644
> --- a/config.h.in
> +++ b/config.h.in
> @@ -123,9 +123,12 @@
>  /* C-SKY ABI version.  */
>  #undef CSKYABI
>  
> -/* C-SKY floating-point ABI.  */
> +/* C-SKY floating-point instructions.  */
>  #undef CSKY_HARD_FLOAT
>  
> +/* C-SKY floating-point ABI.  */
> +#undef CSKY_HARD_FLOAT_ABI
> +
>  /* RISC-V integer ABI for ld.so.  */
>  #undef RISCV_ABI_XLEN
>  
> diff --git a/sysdeps/csky/preconfigure b/sysdeps/csky/preconfigure
> old mode 100644
> new mode 100755
> index 8a6136dd8d..6ba4871d18
> --- a/sysdeps/csky/preconfigure
> +++ b/sysdeps/csky/preconfigure
> @@ -5,10 +5,8 @@ case "$machine" in
>  csky*)
>      abi=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
>        sed -n 's/^#define __CSKYABI__ \(.*\)/\1/p'`
> -    hard_float=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
> -      sed -n 's/^#define __CSKY_HARD_FLOAT__ \(.*\)/\1/p'`
> -    hard_float_sf=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
> -      sed -n 's/^#define __CSKY_HARD_FLOAT_FPU_SF__ \(.*\)/\1/p'`
> +    soft_float=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
> +      sed -n 's/^#define __CSKY_SOFT_FLOAT__ \(.*\)/\1/p'`
>      hard_float_abi=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
>        sed -n 's/^#define __CSKY_HARD_FLOAT_ABI__ \(.*\)/\1/p'`
>  
> @@ -24,26 +22,31 @@ csky*)
>  	;;
>      esac
>  
> -    # __CSKY_HARD_FLOAT_ABI__ was added on gcc 11 to specify whether
> -    # -mfloat-abi=hard is set.  On older gcc, the float ABI is defined solely
> -    # with __CSKY_HARD_FLOAT__.  If __CSKY_HARD_FLOAT__ is set, it can be
> -    # either a hard-float ABI (gcc older than 11, or gcc11 -mfloat-abi=hard
> -    # (__CSKY_HARD_FLOAT_ABI__ is set) or -mfloat-abi=softfp
> -    # (__CSKY_HARD_FLOAT_ABI__ is not set). To be compatible with older gcc,
> -    # use __CSKY_HARD_FLOAT_FPU_SF__ identify if -mfloat-abi is supported,
> -    # because it is added to gcc at the same time as -mfloat-abi.
> -    if test -n "$hard_float"; then
> -	if test -z "$hard_float_sf"; then
> -	    with_fp_cond=1
> -	else
> +    if { ac_try='${CC-cc} -S -mfloat-abi=softfp /dev/null 1>&5'
> +  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> +  (eval $ac_try) 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; }; then
> +      soft_float_abi_support=1
> +    else
> +      soft_float_abi_support=0
> +    fi
> +
> +    if test -n "$soft_float"; then
> +	with_fp_cond=0
> +	with_hard_float_abi=0
> +    else
> +	with_fp_cond=1
> +	if test -n "$soft_float_abi_support"; then
>  	    if test -n "$hard_float_abi"; then
> -		with_fp_cond=1
> +		with_hard_float_abi=1
>  	    else
> -		with_fp_cond=0
> +		with_hard_float_abi=0
>  	    fi
> +	else
> +	    with_hard_float_abi=1
>  	fi
> -    else
> -	with_fp_cond=0
>      fi
>  
>      base_machine=csky
> @@ -55,6 +58,10 @@ _ACEOF
>  
>      cat >>confdefs.h <<_ACEOF
>  #define CSKY_HARD_FLOAT $with_fp_cond
> +_ACEOF
> +
> +    cat >>confdefs.h <<_ACEOF
> +#define CSKY_HARD_FLOAT_ABI $with_hard_float_abi
>  _ACEOF
>  
>      ;;
> diff --git a/sysdeps/csky/preconfigure.ac b/sysdeps/csky/preconfigure.ac
> index 332c0f1cab..7412bcef92 100644
> --- a/sysdeps/csky/preconfigure.ac
> +++ b/sysdeps/csky/preconfigure.ac
> @@ -5,10 +5,8 @@ case "$machine" in
>  csky*)
>      abi=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
>        sed -n 's/^#define __CSKYABI__ \(.*\)/\1/p'`
> -    hard_float=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
> -      sed -n 's/^#define __CSKY_HARD_FLOAT__ \(.*\)/\1/p'`
> -    hard_float_sf=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
> -      sed -n 's/^#define __CSKY_HARD_FLOAT_FPU_SF__ \(.*\)/\1/p'`
> +    soft_float=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
> +      sed -n 's/^#define __CSKY_SOFT_FLOAT__ \(.*\)/\1/p'`
>      hard_float_abi=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
>        sed -n 's/^#define __CSKY_HARD_FLOAT_ABI__ \(.*\)/\1/p'`
>  
> @@ -24,26 +22,26 @@ csky*)
>  	;;
>      esac
>  
> -    # __CSKY_HARD_FLOAT_ABI__ was added on gcc 11 to specify whether
> -    # -mfloat-abi=hard is set.  On older gcc, the float ABI is defined solely
> -    # with __CSKY_HARD_FLOAT__.  If __CSKY_HARD_FLOAT__ is set, it can be
> -    # either a hard-float ABI (gcc older than 11, or gcc11 -mfloat-abi=hard
> -    # (__CSKY_HARD_FLOAT_ABI__ is set) or -mfloat-abi=softfp
> -    # (__CSKY_HARD_FLOAT_ABI__ is not set). To be compatible with older gcc,
> -    # use __CSKY_HARD_FLOAT_FPU_SF__ identify if -mfloat-abi is supported,
> -    # because it is added to gcc at the same time as -mfloat-abi.
> -    if test -n "$hard_float"; then
> -	if test -z "$hard_float_sf"; then
> -	    with_fp_cond=1
> -	else
> +    if AC_TRY_COMMAND(${CC-cc} -S -mfloat-abi=softfp /dev/null 1>&AS_MESSAGE_LOG_FD); then
> +      soft_float_abi_support=1
> +    else
> +      soft_float_abi_support=0
> +    fi

It is not clear to me why you need to use '-mfloat-abi=softfp' to check 
for soft-float ABI, since it *won't* be used to actually build glibc
(meaning that the compiler build invocation not necessary will use the
same ABI as the test is doing).

> +
> +    if test -n "$soft_float"; then
> +	with_fp_cond=0
> +	with_hard_float_abi=0
> +    else
> +	with_fp_cond=1
> +	if test -n "$soft_float_abi_support"; then
>  	    if test -n "$hard_float_abi"; then
> -		with_fp_cond=1
> +		with_hard_float_abi=1
>  	    else
> -		with_fp_cond=0
> +		with_hard_float_abi=0
>  	    fi
> +	else
> +	    with_hard_float_abi=1
>  	fi
> -    else
> -	with_fp_cond=0
>      fi
>  
>      base_machine=csky
> @@ -51,5 +49,6 @@ csky*)
>  
>      AC_DEFINE_UNQUOTED([CSKYABI], [$abi])
>      AC_DEFINE_UNQUOTED([CSKY_HARD_FLOAT], [$with_fp_cond])
> +    AC_DEFINE_UNQUOTED([CSKY_HARD_FLOAT_ABI], [$with_hard_float_abi])
>      ;;
>  esac
> diff --git a/sysdeps/unix/sysv/linux/csky/shlib-versions b/sysdeps/unix/sysv/linux/csky/shlib-versions
> index 8c026356ef..4ab7d6b83e 100644
> --- a/sysdeps/unix/sysv/linux/csky/shlib-versions
> +++ b/sysdeps/unix/sysv/linux/csky/shlib-versions
> @@ -1,8 +1,8 @@
>  DEFAULT			GLIBC_2.29
>  
> -%if CSKYABI == 2 && CSKY_HARD_FLOAT == 1
> +%if CSKYABI == 2 && CSKY_HARD_FLOAT_ABI == 1
>  ld=ld-linux-cskyv2-hf.so.1
> -%elif CSKYABI == 2 && CSKY_HARD_FLOAT == 0
> +%elif CSKYABI == 2 && CSKY_HARD_FLOAT_ABI == 0
>  ld=ld-linux-cskyv2.so.1
>  %else
>  %error cannot determine ABI