I'm hitting the same bug as in PR53708 when compiling GLIBC's dlfcn.c when
vectorization is enabled on powerpc64-linux. A reduced test case is:
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. I'd like to backport Richard's patch below to the 4.7 branch.
The patch bootstrapped and regtested on powerpc64-linux with no regressions.
Is it ok for the 4.7 branch?
Peter
Backport from mainline
2012-06-19 Richard Guenther <[email protected]>
PR tree-optimization/53708
* tree-vect-data-refs.c (vect_can_force_dr_alignment_p): Preserve
user-supplied alignment and alignment of decls with the used
attribute.
Index: gcc/tree-vect-data-refs.c
===================================================================
--- gcc/tree-vect-data-refs.c (revision 192988)
+++ gcc/tree-vect-data-refs.c (working copy)
@@ -4574,6 +4574,12 @@
if (TREE_ASM_WRITTEN (decl))
return false;
+ /* Do not override explicit alignment set by the user or the alignment
+ as specified by the ABI when the used attribute is set. */
+ if (DECL_USER_ALIGN (decl)
+ || DECL_PRESERVE_P (decl))
+ return false;
+
if (TREE_STATIC (decl))
return (alignment <= MAX_OFILE_ALIGNMENT);
else
