2009-09-02 Martin Jambor <mjambor@suse.cz>

	* tree-sra.c (struct access): New field grp_hint.
	(dump_access): Dump grp_hint.
	(sort_and_splice_var_accesses): Set grp_hint if a group is read
	multiple times.
	(analyze_access_subtree): Only scalarize accesses with grp_hint set or
	those which have been specifically read and somehow written to.
	(propagate_subacesses_accross_link): Set grp_hint of right child and
	also possibly of the left child.

	* testsuite/gcc.dg/tree-ssa/sra-8.c: New testcase.
	* testsuite/gcc.dg/memcpy-1.c: Add . to match pattern.
	* testsuite/gcc.dg/uninit-I.c: XFAIL warning test.
	* testsuite/g++.dg/warn/unit-1.C: XFAIL warning test.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@151345 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 37 insertions, 14 deletions

diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
index 33be0f6aaca..8d4dc90d179 100644
--- a/gcc/tree-sra.c
+++ b/gcc/tree-sra.c
@@ -165,6 +165,10 @@ struct access
   /* Does this group contain a read access?  This flag is propagated down the
      access tree.  */
   unsigned grp_read : 1;
+  /* Other passes of the analysis use this bit to make function
+     analyze_access_subtree create scalar replacements for this group if
+     possible.  */
+  unsigned grp_hint : 1;
   /* Is the subtree rooted in this access fully covered by scalar
      replacements?  */
   unsigned grp_covered : 1;
@@ -261,12 +265,14 @@ dump_access (FILE *f, struct access *access, bool grp)
   fprintf (f, ", type = ");
   print_generic_expr (f, access->type, 0);
   if (grp)
-    fprintf (f, ", grp_write = %d, grp_read = %d, grp_covered = %d, "
-	     "grp_unscalarizable_region = %d, grp_unscalarized_data = %d, "
-	     "grp_partial_lhs = %d, grp_to_be_replaced = %d\n",
-	     access->grp_write, access->grp_read, access->grp_covered,
-	     access->grp_unscalarizable_region, access->grp_unscalarized_data,
-	     access->grp_partial_lhs, access->grp_to_be_replaced);
+    fprintf (f, ", grp_write = %d, grp_read = %d, grp_hint = %d, "
+	     "grp_covered = %d, grp_unscalarizable_region = %d, "
+	     "grp_unscalarized_data = %d, grp_partial_lhs = %d, "
+	     "grp_to_be_replaced = %d\n",
+	     access->grp_write, access->grp_read, access->grp_hint,
+	     access->grp_covered, access->grp_unscalarizable_region,
+	     access->grp_unscalarized_data, access->grp_partial_lhs,
+	     access->grp_to_be_replaced);
   else
     fprintf (f, ", write = %d, grp_partial_lhs = %d\n", access->write,
 	     access->grp_partial_lhs);
@@ -1203,8 +1209,9 @@ sort_and_splice_var_accesses (tree var)
   while (i < access_count)
     {
       struct access *access = VEC_index (access_p, access_vec, i);
-      bool modification = access->write;
+      bool grp_write = access->write;
       bool grp_read = !access->write;
+      bool multiple_reads = false;
       bool grp_partial_lhs = access->grp_partial_lhs;
       bool first_scalar = is_gimple_reg_type (access->type);
       bool unscalarizable_region = access->grp_unscalarizable_region;
@@ -1227,8 +1234,15 @@ sort_and_splice_var_accesses (tree var)
 	  struct access *ac2 = VEC_index (access_p, access_vec, j);
 	  if (ac2->offset != access->offset || ac2->size != access->size)
 	    break;
-	  modification |= ac2->write;
-	  grp_read |= !ac2->write;
+	  if (ac2->write)
+	    grp_write = true;
+	  else
+	    {
+	      if (grp_read)
+		multiple_reads = true;
+	      else
+		grp_read = true;
+	    }
 	  grp_partial_lhs |= ac2->grp_partial_lhs;
 	  unscalarizable_region |= ac2->grp_unscalarizable_region;
 	  relink_to_new_repr (access, ac2);
@@ -1244,8 +1258,9 @@ sort_and_splice_var_accesses (tree var)
       i = j;
 
       access->group_representative = access;
-      access->grp_write = modification;
+      access->grp_write = grp_write;
       access->grp_read = grp_read;
+      access->grp_hint = multiple_reads;
       access->grp_partial_lhs = grp_partial_lhs;
       access->grp_unscalarizable_region = unscalarizable_region;
       if (access->first_link)
@@ -1377,6 +1392,7 @@ analyze_access_subtree (struct access *root, bool allow_replacements,
   HOST_WIDE_INT covered_to = root->offset;
   bool scalar = is_gimple_reg_type (root->type);
   bool hole = false, sth_created = false;
+  bool direct_read = root->grp_read;
 
   if (mark_read)
     root->grp_read = true;
@@ -1405,7 +1421,9 @@ analyze_access_subtree (struct access *root, bool allow_replacements,
       hole |= !child->grp_covered;
     }
 
-  if (allow_replacements && scalar && !root->first_child)
+  if (allow_replacements && scalar && !root->first_child
+      && (root->grp_hint
+	  || (direct_read && root->grp_write)))
     {
       if (dump_file && (dump_flags & TDF_DETAILS))
 	{
@@ -1543,7 +1561,6 @@ propagate_subacesses_accross_link (struct access *lacc, struct access *racc)
 {
   struct access *rchild;
   HOST_WIDE_INT norm_delta = lacc->offset - racc->offset;
-
   bool ret = false;
 
   if (is_gimple_reg_type (lacc->type)
@@ -1570,8 +1587,13 @@ propagate_subacesses_accross_link (struct access *lacc, struct access *racc)
       if (child_would_conflict_in_lacc (lacc, norm_offset, rchild->size,
 					&new_acc))
 	{
-	  if (new_acc && rchild->first_child)
-	    ret |= propagate_subacesses_accross_link (new_acc, rchild);
+	  if (new_acc)
+	    {
+	      rchild->grp_hint = 1;
+	      new_acc->grp_hint |= new_acc->grp_read;
+	      if (rchild->first_child)
+		ret |= propagate_subacesses_accross_link (new_acc, rchild);
+	    }
 	  continue;
 	}
 
@@ -1582,6 +1604,7 @@ propagate_subacesses_accross_link (struct access *lacc, struct access *racc)
 				 rchild->type, false))
 	continue;
 
+      rchild->grp_hint = 1;
       new_acc = create_artificial_child_access (lacc, rchild, norm_offset);
       if (racc->first_child)
 	propagate_subacesses_accross_link (new_acc, rchild);