Thanks Yufeng for the review.
On 07/12/13 03:18, Yufeng Zhang wrote:
>> gcc trunk aarch64 bootstrapping fails with gas version 2.23.2 (with
>> error message similar to cannot compute suffix of object files) as this
>> particular version does not support -mabi=lp64. It succeeds with later
>> versions of gas that supports -mabi.
>
> The -mabi option was introduced to gas when the support for ILP32 was
> added. Initially the options were named -milp32 and -mlp64:
>
> http://sourceware.org/ml/binutils/2013-06/msg00178.html
>
> and later on they were change to -mabi=ilp32 and -mabi=lp64 for
> consistency with those in the aarch64 gcc:
>
> http://sourceware.org/ml/binutils/2013-07/msg00180.html
>
> The following gcc patch made the driver use the explicit option to drive
> gas:
>
> http://gcc.gnu.org/ml/gcc-patches/2013-07/msg00083.html
>
> It is a neglect of the backward compatibility with binutils 2.23.
>
>>
>> Attached patch add checking for -mabi=lp64 and prompts upgradation. Is
>> this Ok?
>
> I think instead of mandating the support for the -mabi option, the
> compiler shall be changed able to work with binutils 2.23. The 2.23
> binutils have a good support for aarch64 and the main difference from
> 2.24 is the ILP32 support. I think it is necessary to maintain the
> backward compatibility, and it should be achieved by suppressing the
> compiler's support for ILP32 when the -mabi option is not found
> available in gas during the configuration time.
>
> I had a quick look at areas need to be updated:
>
> * multilib support
>
> In gcc/config.gcc, the default and the only accepted value for
> --with-multilib-list and --with-abi shall be lp64 when -mabi is not
> available.
>
> * -mabi option
>
> I suggest we keep the -mabi option, but reject -mabi=ilp32 in
> gcc/config/aarch64/aarch64.c:aarch64_override_options ()
>
> * driver spec
>
> In gcc/config/aarch64/aarch64-elf.h, the DRIVER_SELF_SPECS and ASM_SPEC
> shall be updated to not pass/specify -mabi for gas.
>
> * documentation
>
> I think it needs to be mentioned in gcc/doc/install.texi the constraint
> of using pre-2.24 binutils with aarch64 gcc that is 4.9 or later.
>
> It is a quick scouting, but hopefully it has provided provide some
> guidance. If you need more help, just let me know.
>
>
> Yufeng
>
> P.s. some minor comments on the attached patch.
>
>>
>> diff --git a/gcc/configure b/gcc/configure
>> index fdf0cd0..17b6e85 100755
>> --- a/gcc/configure
>> +++ b/gcc/configure
>
> Diff result of auto-generation is usually excluded from a patch.
>
>> diff --git a/gcc/configure.ac b/gcc/configure.ac
>> index 91a22d5..730ada0 100644
>> --- a/gcc/configure.ac
>> +++ b/gcc/configure.ac
>> @@ -3532,6 +3532,15 @@ case "$target" in
>> [Define if your assembler supports the -no-mul-bug-abort
>> option.])])
>> ;;
>>
>> + aarch64-*-*)
>
> aarch64*-*-*
>
>> + gcc_GAS_CHECK_FEATURE([-mabi option],
>> + gcc_cv_as_aarch64_mabi,,
>> + [-mabi=lp64], [.text],,,)
>> + if test x$gcc_cv_as_aarch64_mabi = xno; then
>> + AC_MSG_ERROR([Assembler support for -mabi=lp64 is required.
>> Upgrade the Assembler.])
>> + fi
>> + ;;
>> +
>> sparc*-*-*)
>> gcc_GAS_CHECK_FEATURE([.register], gcc_cv_as_sparc_register_op,,,
>> [.register %g2, #scratch],,
>>
>
>
Here is an attempt to do it the way you have suggested.
Thanks,
Kugan
gcc/
+2013-12-09 Kugan Vivekanandarajah <kug...@linaro.org>
+ * configure.ac: Add check for aarch64 assembler -mabi support.
+ * configure: Regenerate.
+ * config.in: Regenerate.
+ * config/aarch64/aarch64-elf.h (ASM_MABI_SPEC): New define.
+ (ASM_SPEC): Update to substitute -mabi with ASM_MABI_SPEC.
+ * config/aarch64/aarch64.h (aarch64_override_options): Issue error if
+ Assembler does not support -mabi and option ilp32 is selected.
+ * doc/install.texi: Added note that building gcc 4.9 and after with pre
+ 2.24 binutils will not support -mabi=ilp32.
+
diff --git a/gcc/config/aarch64/aarch64-elf.h b/gcc/config/aarch64/aarch64-elf.h
index 4757d22..b260b7c 100644
--- a/gcc/config/aarch64/aarch64-elf.h
+++ b/gcc/config/aarch64/aarch64-elf.h
@@ -134,13 +134,19 @@
" %{!mbig-endian:%{!mlittle-endian:" ENDIAN_SPEC "}}" \
" %{!mabi=*:" ABI_SPEC "}"
+#ifdef HAVE_AS_MABI_OPTION
+#define ASM_MABI_SPEC "%{mabi=*:-mabi=%*}"
+#else
+#define ASM_MABI_SPEC "%{mabi=lp64*:}"
+#endif
+
#ifndef ASM_SPEC
#define ASM_SPEC "\
%{mbig-endian:-EB} \
%{mlittle-endian:-EL} \
%{mcpu=*:-mcpu=%*} \
-%{march=*:-march=%*} \
-%{mabi=*:-mabi=%*}"
+%{march=*:-march=%*}" \
+ASM_MABI_SPEC
#endif
#undef TYPE_OPERAND_FMT
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index b1b4eef..c1a9cbd 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -5186,6 +5186,10 @@ aarch64_override_options (void)
{
aarch64_parse_tune ();
}
+#ifndef HAVE_AS_MABI_OPTION
+ if (TARGET_ILP32)
+ error ("Assembler does not supprt -mabi=ilp32");
+#endif
initialize_aarch64_code_model ();
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 91a22d5..fcfdbdb 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -3532,6 +3532,19 @@ case "$target" in
[Define if your assembler supports the -no-mul-bug-abort
option.])])
;;
+ aarch64*-*-*)
+ gcc_GAS_CHECK_FEATURE([-mabi option],
+ gcc_cv_as_aarch64_mabi,,
+ [-mabi=lp64], [.text],,,)
+ if test $gcc_cv_as_aarch64_mabi = yes ; then
+ AC_DEFINE(HAVE_AS_MABI_OPTION, 1,
+ [Define if your assembler supports the -mabi option.])
+ fi
+ if test x$gcc_cv_as_aarch64_mabi = xno && test x$with_abi = xilp32; then
+ AC_MSG_ERROR([Assembler doesnot support -mabi=ilp32. Upgrade the
Assembler.])
+ fi
+ ;;
+
sparc*-*-*)
gcc_GAS_CHECK_FEATURE([.register], gcc_cv_as_sparc_register_op,,,
[.register %g2, #scratch],,
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index a8f9f8a..e4de2d2 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -3735,6 +3735,15 @@ removed and the system libunwind library will always be
used.
@html
<hr />
+@end html
+@anchor{aarch64-x-x}
+@heading aarch64-*-*
+Pre 2.24 binutils does not have support for selecting -mabi and does not
+support ILP32. If GCC 4.9 or later is built with pre 2.24, GCC will not
+support option -mabi=ilp32.
+
+@html
+<hr />
<!-- rs6000-ibm-aix*, powerpc-ibm-aix* -->
@end html
@anchor{x-ibm-aix}
