[Bug middle-end/53708] [4.8 Regression] Many failures of the objc tests with -O3 -fnext-runtime and -m32

["bergner at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53708

Peter Bergner <bergner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
                 CC|                            |bergner at gcc dot gnu.org
         Resolution|FIXED                       |

--- Comment #9 from Peter Bergner <bergner at gcc dot gnu.org> 2012-10-30 15:47:57 UTC ---
Richard, I'm seeing this same bug in GCC 4.7 on powerpc64-linux when compiling
GLIBC.  Is there a chance we can get your patch backported to 4.7?  I
bootstrapped and regtested the backport with no regressions and can confirm it
fixes the bug I'm running into, which can be seen with the reduced test case
from glibc:

bergner@bns:~/gcc/BUGS> cat foo.i 
static void (*const init_array []) (void)
  __attribute__ ((section (".init_array"), aligned (sizeof (void *)), used))
= { 0 };

bergner@bns:~/gcc/BUGS> /home/bergner/gcc/build/gcc-fsf-4_7-base/gcc/xgcc
-B/home/bergner/gcc/build/gcc-fsf-4_7-base/gcc -S -m64 -O3 -maltivec foo.i -o
bad.s

bergner@bns:~/gcc/BUGS> /home/bergner/gcc/build/gcc-fsf-4_7-pr53708/gcc/xgcc
-B/home/bergner/gcc/build/gcc-fsf-4_7-pr53708/gcc -S -m64 -O3 -maltivec foo.i
-o good.s

bergner@bns:~/gcc/BUGS> diff -u bad.s good.s 
--- bad.s    2012-10-30 10:41:15.000000000 -0500
+++ good.s    2012-10-30 10:41:23.000000000 -0500
@@ -2,7 +2,7 @@
     .section    ".toc","aw"
     .section    ".text"
     .section    .init_array,"a"
-    .align 4
+    .align 3
     .type    init_array, @object
     .size    init_array, 8
 init_array:

The above is bad, because the extra alignment causes the linker to add some
null padding to the init_array and the loader isn't expecting that and ends up
segv'ing.