[COMMITTED][AArch64] Fall back to -fPIC if no support of -fpic relocation modifer in assembler

[Jiong Wang <jiong dot wang at arm dot com>]

James Greenhalgh writes:

> On Mon, Jun 29, 2015 at 01:42:13PM +0100, Jiong Wang wrote:
>> 
>> This patch fix the breakage caused by
>> 
>>   https://gcc.gnu.org/ml/gcc-patches/2015-06/msg01913.html
>> 
>> We fall back to -fPIC if there is no assembler support on those new
>> relocation modifiers for -fpic.
>> 
>> OK for trunk?
>> 
>> gcc/
>>   * configure.ac: Add check for aarch64 assembler -fpic relocation
>>   modifier support.
>>   * configure: Regenerate.
>>   * config.in: Regenerate.
>>   * config/aarch64/aarch64.c (initialize_aarch64_code_model): Fall back to
>>   -fPIC if not support of -fpic relocation modifier in assembler.
>> -- 
>> Regards,
>> Jiong
>
> This patch is OK, but please rename
>
>> +#undef HAVE_AS_SPIC_RELOCS
>
> to
>
>   HAVE_AS_SMALL_PIC_RELOCS
>
> It seems clearer to explicitly spell out what feature this relates to.

Thanks, commited below patch as 225231.

Index: gcc/config/aarch64/aarch64.c
===================================================================
--- gcc/config/aarch64/aarch64.c	(revision 225228)
+++ gcc/config/aarch64/aarch64.c	(working copy)
@@ -7581,9 +7581,13 @@
 	   aarch64_cmodel = AARCH64_CMODEL_TINY_PIC;
 	   break;
 	 case AARCH64_CMODEL_SMALL:
+#ifdef HAVE_AS_SMALL_PIC_RELOCS
 	   aarch64_cmodel = (flag_pic == 2
 			     ? AARCH64_CMODEL_SMALL_PIC
 			     : AARCH64_CMODEL_SMALL_SPIC);
+#else
+	   aarch64_cmodel = AARCH64_CMODEL_SMALL_PIC;
+#endif
 	   break;
 	 case AARCH64_CMODEL_LARGE:
 	   sorry ("code model %qs with -f%s", "large",
Index: gcc/config.in
===================================================================
--- gcc/config.in	(revision 225228)
+++ gcc/config.in	(working copy)
@@ -606,6 +606,12 @@
 #endif
 
 
+/* Define if your assembler supports relocs needed by -fpic. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_AS_SMALL_PIC_RELOCS
+#endif
+
+
 /* Define if your assembler and linker support thread-local storage. */
 #ifndef USED_FOR_TARGET
 #undef HAVE_AS_TLS
Index: gcc/configure
===================================================================
--- gcc/configure	(revision 225228)
+++ gcc/configure	(working copy)
@@ -24228,6 +24228,40 @@
         done
       fi
     fi
+    # Check if we have binutils support for relocations types needed by -fpic
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for -fpic relocs" >&5
+$as_echo_n "checking assembler for -fpic relocs... " >&6; }
+if test "${gcc_cv_as_aarch64_picreloc+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  gcc_cv_as_aarch64_picreloc=no
+  if test x$gcc_cv_as != x; then
+    $as_echo '
+	.text
+	ldr     x0, [x2, #:gotpage_lo15:globalsym]
+    ' > conftest.s
+    if { ac_try='$gcc_cv_as $gcc_cv_as_flags  -o conftest.o conftest.s >&5'
+  { { eval echo "\"\$as_me\":${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_aarch64_picreloc=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: $gcc_cv_as_aarch64_picreloc" >&5
+$as_echo "$gcc_cv_as_aarch64_picreloc" >&6; }
+if test $gcc_cv_as_aarch64_picreloc = yes; then
+
+$as_echo "#define HAVE_AS_SMALL_PIC_RELOCS 1" >>confdefs.h
+
+fi
     # Enable default workaround for AArch64 Cortex-A53 erratum 835769.
     # Check whether --enable-fix-cortex-a53-835769 was given.
 if test "${enable_fix_cortex_a53_835769+set}" = set; then :
Index: gcc/configure.ac
===================================================================
--- gcc/configure.ac	(revision 225228)
+++ gcc/configure.ac	(working copy)
@@ -3562,6 +3562,13 @@
         done
       fi
     fi
+    # Check if we have binutils support for relocations types needed by -fpic
+    gcc_GAS_CHECK_FEATURE([-fpic relocs], gcc_cv_as_aarch64_picreloc,,,
+    [
+	.text
+	ldr     x0, [[x2, #:gotpage_lo15:globalsym]]
+    ],,[AC_DEFINE(HAVE_AS_SMALL_PIC_RELOCS, 1,
+	[Define if your assembler supports relocs needed by -fpic.])])
     # Enable default workaround for AArch64 Cortex-A53 erratum 835769.
     AC_ARG_ENABLE(fix-cortex-a53-835769,
     [