diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 04e1a00e07b..3eaf5648185 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2012-03-14  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/52571
+	* tree-vect-data-refs.c (vect_compute_data_ref_alignment): Move
+	flag_section_anchors check ...
+	(vect_can_force_dr_alignment_p): ... here.  Do not re-align
+	DECL_COMMON variables.
+
 2012-03-14  Richard Guenther  <rguenther@suse.de>
 
 	* tree.h (DECL_BIT_FIELD_REPRESENTATIVE): New define.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 406f0959f51..1ce4c103a12 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2012-03-14  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/52571
+	* gcc.dg/vect/vect-2.c: Initialize arrays.
+	* gcc.dg/vect/no-section-anchors-vect-34.c: Likewise.
+	* gcc.target/i386/recip-vec-divf.c: Use -fno-common.
+	* gcc.target/i386/recip-vec-sqrtf.c: Likewise.
+
 2012-03-14  Richard Guenther  <rguenther@suse.de>
 
 	PR middle-end/52080
diff --git a/gcc/testsuite/gcc.dg/vect/no-section-anchors-vect-34.c b/gcc/testsuite/gcc.dg/vect/no-section-anchors-vect-34.c
index 2eac33e414b..7600edf160d 100644
--- a/gcc/testsuite/gcc.dg/vect/no-section-anchors-vect-34.c
+++ b/gcc/testsuite/gcc.dg/vect/no-section-anchors-vect-34.c
@@ -7,7 +7,7 @@
  
 struct {
   char ca[N];
-} s;
+} s = {};
 char cb[N] = {0,3,6,9,12,15,18,21,24,27,30,33,36,39,42,45};
 
 __attribute__ ((noinline))
diff --git a/gcc/testsuite/gcc.dg/vect/vect-2.c b/gcc/testsuite/gcc.dg/vect/vect-2.c
index 5d4fc914a97..f01b7b46ddc 100644
--- a/gcc/testsuite/gcc.dg/vect/vect-2.c
+++ b/gcc/testsuite/gcc.dg/vect/vect-2.c
@@ -6,7 +6,7 @@
 #define N 16
 
 char cb[N] = {0,3,6,9,12,15,18,21,24,27,30,33,36,39,42,45};
-char ca[N];
+char ca[N] = {};
 
 __attribute__ ((noinline)) 
 int main1 ()
diff --git a/gcc/testsuite/gcc.target/i386/recip-vec-divf.c b/gcc/testsuite/gcc.target/i386/recip-vec-divf.c
index 0c0cd42ae8a..fa126e45f6f 100644
--- a/gcc/testsuite/gcc.target/i386/recip-vec-divf.c
+++ b/gcc/testsuite/gcc.target/i386/recip-vec-divf.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -ffast-math -ftree-vectorize -msse -mfpmath=sse -mrecip" } */
+/* { dg-options "-O2 -ffast-math -ftree-vectorize -msse -mfpmath=sse -mrecip -fno-common" } */
 
 float a[4];
 float b[4];
diff --git a/gcc/testsuite/gcc.target/i386/recip-vec-sqrtf.c b/gcc/testsuite/gcc.target/i386/recip-vec-sqrtf.c
index 9ac9bd76ce9..6c0d49b2214 100644
--- a/gcc/testsuite/gcc.target/i386/recip-vec-sqrtf.c
+++ b/gcc/testsuite/gcc.target/i386/recip-vec-sqrtf.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -ffast-math -ftree-vectorize -msse -mfpmath=sse -mrecip" } */
+/* { dg-options "-O2 -ffast-math -ftree-vectorize -msse -mfpmath=sse -mrecip -fno-common" } */
 
 float a[4];
 float b[4];
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index b458d624d64..9b66d86d124 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -872,10 +872,7 @@ vect_compute_data_ref_alignment (struct data_reference *dr)
 
   if (!base_aligned)
     {
-      /* Do not change the alignment of global variables if
-	 flag_section_anchors is enabled.  */
-      if (!vect_can_force_dr_alignment_p (base, TYPE_ALIGN (vectype))
-	  || (TREE_STATIC (base) && flag_section_anchors))
+      if (!vect_can_force_dr_alignment_p (base, TYPE_ALIGN (vectype)))
 	{
 	  if (vect_print_dump_info (REPORT_DETAILS))
 	    {
@@ -4546,12 +4543,22 @@ vect_can_force_dr_alignment_p (const_tree decl, unsigned int alignment)
   if (TREE_CODE (decl) != VAR_DECL)
     return false;
 
-  if (DECL_EXTERNAL (decl))
+  /* We cannot change alignment of common or external symbols as another
+     translation unit may contain a definition with lower alignment.  
+     The rules of common symbol linking mean that the definition
+     will override the common symbol.  */
+  if (DECL_EXTERNAL (decl)
+      || DECL_COMMON (decl))
     return false;
 
   if (TREE_ASM_WRITTEN (decl))
     return false;
 
+  /* Do not change the alignment of global variables if flag_section_anchors
+     is enabled.  */
+  if (TREE_STATIC (decl) && flag_section_anchors)
+    return false;
+
   if (TREE_STATIC (decl))
     return (alignment <= MAX_OFILE_ALIGNMENT);
   else