diff mbox

AARCH64 configure check for gas -mabi support

Message ID 52A5A765.7000106@linaro.org
State Superseded
Headers show

Commit Message

Kugan Vivekanandarajah Dec. 9, 2013, 11:20 a.m. UTC 
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  <kuganv@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 mbox

Patch

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}