RE: [PATCH][4.9] PR 64569 - Backport support for MIPS binutils 2.25

[Matthew Fortune <Matthew dot Fortune at imgtec dot com>]

> This is a minimal backport of features added to GCC 5 to enable use
> of binutils 2.25 with GCC 4.9 for MIPS soft-float builds. Further
> details in the PR:
> 
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64569
> 
> The commits which are being backported are listed below (the last
> one is posted but not committed yet).
> 
> r213870: Fix mips16.S for soft-float
> r213872: Pass -m(soft|hard|single|double)-float via ASM_SPEC
> r217446: Implement o32 FPXX (very minimal backport)
> r217939: Update configure check for HAVE_MIPS_DOT_MODULE
> r??????: Make ASM_SPEC changes conditional on HAVE_MIPS_DOT_MODULE

Updated - The last one in the list is committed as:
r219867: MIPS: Only pass floating-point options to the assembler when necessary

I'm not sure who to CC as RM for GCC 4.9.

Thanks,
Matthew

> 
> gcc/
> 	* config.in [!USED_FOR_TARGET] (HAVE_AS_DOT_MODULE): Undefine.
> 	* config/mips/mips.h (FP_ASM_SPEC): New macro.
> 	(ASM_SPEC): Use FP_ASM_SPEC.
> 	* configure.ac (HAVE_AS_DOT_MODULE): Detect support for .module
> 	and FPXX extensions.
> 
> libgcc/
> 	* config/mips/mips16.S: Do not build for soft-float.
> 
> Once this is done I will do the same backport for GCC 4.8.
> 
> Tested to check that soft-float builds work with binutils 2.25 and
> the floating-point options are not passed for binutils 2.24.
> 
> Thanks,
> Matthew
> 
> ---
>  gcc/config.in               |  6 ++++++
>  gcc/config/mips/mips.h      | 19 ++++++++++++++++++-
>  gcc/configure               | 32 ++++++++++++++++++++++++++++++++
>  gcc/configure.ac            |  7 +++++++
>  libgcc/config/mips/mips16.S | 10 +++++++---
>  5 files changed, 70 insertions(+), 4 deletions(-)
> 
> diff --git a/gcc/config.in b/gcc/config.in
> index 1e85325..013a606 100644
> --- a/gcc/config.in
> +++ b/gcc/config.in
> @@ -447,6 +447,12 @@
>  #endif
> 
> 
> +/* Define if the assembler understands .module. */
> +#ifndef USED_FOR_TARGET
> +#undef HAVE_AS_DOT_MODULE
> +#endif
> +
> +
>  /* Define if your assembler supports the -no-mul-bug-abort option. */
>  #ifndef USED_FOR_TARGET
>  #undef HAVE_AS_NO_MUL_BUG_ABORT_OPTION
> diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
> index a786d4c..ff88d98 100644
> --- a/gcc/config/mips/mips.h
> +++ b/gcc/config/mips/mips.h
> @@ -1163,6 +1163,22 @@ struct mips_cpu_info {
>  #define SUBTARGET_ASM_SPEC ""
>  #endif
> 
> +/* FP_ASM_SPEC represents the floating-point options that must be passed
> +   to the assembler when FPXX support exists.  Prior to that point the
> +   assembler could accept the options but were not required for
> +   correctness.  We only add the options when absolutely necessary
> +   because passing -msoft-float to the assembler will cause it to reject
> +   all hard-float instructions which may require some user code to be
> +   updated.  */
> +
> +#ifdef HAVE_AS_DOT_MODULE
> +#define FP_ASM_SPEC "\
> +%{mhard-float} %{msoft-float} \
> +%{msingle-float} %{mdouble-float}"
> +#else
> +#define FP_ASM_SPEC
> +#endif
> +
>  #undef ASM_SPEC
>  #define ASM_SPEC "\
>  %{G*} %(endian_spec) %{mips1} %{mips2} %{mips3} %{mips4} \
> @@ -1188,7 +1204,8 @@ struct mips_cpu_info {
>  %{mfp32} %{mfp64} %{mnan=*} \
>  %{mshared} %{mno-shared} \
>  %{msym32} %{mno-sym32} \
> -%{mtune=*} \
> +%{mtune=*}" \
> +FP_ASM_SPEC "\
>  %(subtarget_asm_spec)"
> 
>  /* Extra switches sometimes passed to the linker.  */
> diff --git a/gcc/configure b/gcc/configure
> index 291e463..d5b6879 100755
> --- a/gcc/configure
> +++ b/gcc/configure
> @@ -26140,6 +26140,38 @@ $as_echo "#define HAVE_AS_GNU_ATTRIBUTE 1"
> >>confdefs.h
> 
>  fi
> 
> +    { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for
> .module support" >&5
> +$as_echo_n "checking assembler for .module support... " >&6; }
> +if test "${gcc_cv_as_mips_dot_module+set}" = set; then :
> +  $as_echo_n "(cached) " >&6
> +else
> +  gcc_cv_as_mips_dot_module=no
> +  if test x$gcc_cv_as != x; then
> +    $as_echo '.module mips2
> +       .module fp=xx' > conftest.s
> +    if { ac_try='$gcc_cv_as $gcc_cv_as_flags -32 -o conftest.o conftest.s
> >&5'
> +  { { eval echo "\"\$as_me\":${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
> +	gcc_cv_as_mips_dot_module=yes
> +    else
> +      echo "configure: failed program was" >&5
> +      cat conftest.s >&5
> +    fi
> +    rm -f conftest.o conftest.s
> +  fi
> +fi
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result:
> $gcc_cv_as_mips_dot_module" >&5
> +$as_echo "$gcc_cv_as_mips_dot_module" >&6; }
> +if test $gcc_cv_as_mips_dot_module = yes; then
> +
> +$as_echo "#define HAVE_AS_DOT_MODULE 1" >>confdefs.h
> +
> +fi
> +
>      { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for
> .micromips support" >&5
>  $as_echo_n "checking assembler for .micromips support... " >&6; }
>  if test "${gcc_cv_as_micromips_support+set}" = set; then :
> diff --git a/gcc/configure.ac b/gcc/configure.ac
> index b9a3799..ded0c48 100644
> --- a/gcc/configure.ac
> +++ b/gcc/configure.ac
> @@ -4251,6 +4251,13 @@ LCF0:
>        [AC_DEFINE(HAVE_AS_GNU_ATTRIBUTE, 1,
>  	  [Define if your assembler supports .gnu_attribute.])])
> 
> +    gcc_GAS_CHECK_FEATURE([.module support],
> +      gcc_cv_as_mips_dot_module,,[-32],
> +      [.module mips2
> +       .module fp=xx],,
> +      [AC_DEFINE(HAVE_AS_DOT_MODULE, 1,
> +	  [Define if your assembler supports .module.])])
> +
>      gcc_GAS_CHECK_FEATURE([.micromips support],
>        gcc_cv_as_micromips_support,,[--fatal-warnings],
>        [.set micromips],,
> diff --git a/libgcc/config/mips/mips16.S b/libgcc/config/mips/mips16.S
> index 6a43a98..dde8939 100644
> --- a/libgcc/config/mips/mips16.S
> +++ b/libgcc/config/mips/mips16.S
> @@ -21,8 +21,12 @@ a copy of the GCC Runtime Library Exception along with
> this program;
>  see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
>  <http://www.gnu.org/licenses/>.  */
> 
> -#ifdef __mips_micromips
> -  /* DO NOTHING */
> +#if defined(__mips_micromips) || defined(__mips_soft_float)
> +  /* Do nothing because this code is only needed when linking
> +     against mips16 hard-float objects.  Neither micromips code
> +     nor soft-float code can be linked against mips16 hard-float
> +     objects so we do not need these routines when building libgcc
> +     for those cases.  */
>  #else
> 
>  /* This file contains mips16 floating point support functions.  These
> @@ -749,4 +753,4 @@ CALL_STUB_RET (__mips16_call_stub_dc_10, 10, DC)
>  #endif /* !__mips_single_float */
> 
>  #endif
> -#endif /* __mips_micromips */
> +#endif /* defined(__mips_micromips) || defined(__mips_soft_float) */
> --
> 2.2.1