Fix vectorizer alignment update wrt section anchors

[Jan Hubicka <hubicka at ucw dot cz>]

Hi,
this patch avoids notice_global_symbol to create DECL_RTL prior IPA
optimization.  Consequently symtab_node::can_increase_alignment_p can check for
presence of DECL_RTL with section anchor. This makes it possible to bump up
alignment in tree-vect-data-refs.c in some cases (when DECL_RTL is not computed
yet).

I suppose vectorizer can also be updated to just bump up alingmnet of the
section and then use the known offset within the section.

Bootstrapped/regtested x86_64-linux and ppc64-linux, will commit it tomorrow
if there are no better ideas for fix.

	PR tree-optimization/65355
	* varasm.c (notice_global_symbol): Do not produce RTL.
	* symtab.c (symtab_node::can_increase_alignment_p): Check for section
	anchor.
	* tree-vect-data-refs.c (vect_compute_data_ref_alignment): Do not
	check for section anchors.
	* gcc.dg/vect/section-anchors-vect-69.c: Update template.
Index: testsuite/gcc.dg/vect/section-anchors-vect-69.c
===================================================================
--- testsuite/gcc.dg/vect/section-anchors-vect-69.c	(revision 221274)
+++ testsuite/gcc.dg/vect/section-anchors-vect-69.c	(working copy)
@@ -115,6 +115,6 @@ int main (void)
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 0 "vect" } } */
 /* Alignment forced using versioning until the pass that increases alignment
   is extended to handle structs.  */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 4 "vect" { target {vect_int && vector_alignment_reachable } } } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 2 "vect" { target {vect_int && vector_alignment_reachable } } } } */
 /* { dg-final { scan-tree-dump-times "Alignment of access forced using versioning" 4 "vect" { target {vect_int && {! vector_alignment_reachable} } } } } */
 /* { dg-final { cleanup-tree-dump "vect" } } */
Index: varasm.c
===================================================================
--- varasm.c	(revision 221269)
+++ varasm.c	(working copy)
@@ -1630,35 +1630,30 @@ default_ctor_section_asm_out_constructor
 void
 notice_global_symbol (tree decl)
 {
-  const char **type = &first_global_object_name;
+  const char **t = &first_global_object_name;
 
   if (first_global_object_name
       || !TREE_PUBLIC (decl)
       || DECL_EXTERNAL (decl)
       || !DECL_NAME (decl)
+      || (TREE_CODE (decl) == VAR_DECL && DECL_HARD_REGISTER (decl))
       || (TREE_CODE (decl) != FUNCTION_DECL
 	  && (TREE_CODE (decl) != VAR_DECL
 	      || (DECL_COMMON (decl)
 		  && (DECL_INITIAL (decl) == 0
-		      || DECL_INITIAL (decl) == error_mark_node))))
-      || !MEM_P (DECL_RTL (decl)))
+		      || DECL_INITIAL (decl) == error_mark_node)))))
     return;
 
   /* We win when global object is found, but it is useful to know about weak
      symbol as well so we can produce nicer unique names.  */
   if (DECL_WEAK (decl) || DECL_ONE_ONLY (decl) || flag_shlib)
-    type = &weak_global_object_name;
+    t = &weak_global_object_name;
 
-  if (!*type)
+  if (!*t)
     {
-      const char *p;
-      const char *name;
-      rtx decl_rtl = DECL_RTL (decl);
-
-      p = targetm.strip_name_encoding (XSTR (XEXP (decl_rtl, 0), 0));
-      name = ggc_strdup (p);
-
-      *type = name;
+      tree id = DECL_ASSEMBLER_NAME (decl);
+      ultimate_transparent_alias_target (&id);
+      *t = ggc_strdup (targetm.strip_name_encoding (IDENTIFIER_POINTER (id)));
     }
 }
 
Index: symtab.c
===================================================================
--- symtab.c	(revision 221268)
+++ symtab.c	(working copy)
@@ -1924,6 +1924,13 @@ symtab_node::can_increase_alignment_p (v
   if (TREE_ASM_WRITTEN (target->decl))
     return false;
 
+  /* If target is already placed in an anchor, we can not touch its
+     alignment.  */
+  if (DECL_RTL_SET_P (target->decl)
+      && MEM_P (DECL_RTL (target->decl))
+      && SYMBOL_REF_HAS_BLOCK_INFO_P (XEXP (DECL_RTL (target->decl), 0)))
+    return false;
+
   /* Constant pool entries may be shared.  */
   if (DECL_IN_CONSTANT_POOL (target->decl))
     return false;
Index: tree-vect-data-refs.c
===================================================================
--- tree-vect-data-refs.c	(revision 221268)
+++ tree-vect-data-refs.c	(working copy)
@@ -758,12 +758,7 @@ vect_compute_data_ref_alignment (struct
 	  && TREE_CODE (TREE_OPERAND (base, 0)) == ADDR_EXPR)
 	base = TREE_OPERAND (TREE_OPERAND (base, 0), 0);
 
-      /* Do not change the alignment of global variables here if
-	 flag_section_anchors is enabled as we already generated
-	 RTL for other functions.  Most global variables should
-	 have been aligned during the IPA increase_alignment pass.  */
-      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 (dump_enabled_p ())
 	    {