tree-ssa-sccvn.c (vn_reference_lookup_3): Avoid redundant lookups, make looking…

tree-ssa-sccvn.c (vn_reference_lookup_3): Avoid redundant lookups, make looking through aggregate copies stronger.

2011-08-11  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-sccvn.c (vn_reference_lookup_3): Avoid redundant
	lookups, make looking through aggregate copies stronger.

	* g++.dg/tree-ssa/pr41186.C: Un-XFAIL.

From-SVN: r177672

gcc/ChangeLog

+2011-08-11  Richard Guenther  <rguenther@suse.de>
+
+	* tree-ssa-sccvn.c (vn_reference_lookup_3): Avoid redundant
+	lookups, make looking through aggregate copies stronger.
+
 2011-08-11  Richard Henderson  <rth@redhat.com>
 
 	PR bootstrap/50018

gcc/testsuite/ChangeLog

+2011-08-11  Richard Guenther  <rguenther@suse.de>
+
+	* g++.dg/tree-ssa/pr41186.C: Un-XFAIL.
+
 2011-08-11  Michael Matz  <matz@suse.de>
 
 	* gcc.dg/graphite/run-id-pr47593.c: Remove -m32.

gcc/testsuite/g++.dg/tree-ssa/pr41186.C

 /* { dg-do compile } */
-/* { dg-options "-O -fdump-tree-fre1-details" } */
+/* { dg-options "-O -fno-tree-sra -fdump-tree-fre1-details" } */
 
 struct Foo {
   Foo() {};
@@ -30,6 +30,6 @@ int main()
 }
 
 /* { dg-final { scan-tree-dump "Replaced b1.b with 1" "fre1" } } */
-/* { dg-final { scan-tree-dump "Replaced b1.i with 0" "fre1" { xfail *-*-* } } } */
-/* { dg-final { scan-tree-dump "Replaced b1.f with 1" "fre1" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump "Replaced b1.D.\[0-9\]*.i with 0" "fre1" } } */
+/* { dg-final { scan-tree-dump "Replaced b1.D.\[0-9\]*.f with 1" "fre1" } } */
 /* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/tree-ssa-sccvn.c

@@ -1351,18 +1351,28 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_)
     {
       VEC (vn_reference_op_s, heap) *tem;
       tree lhs = gimple_assign_lhs (def_stmt);
+      bool valueized_anything = false;
       /* Avoid re-allocation overhead.  */
       VEC_truncate (vn_reference_op_s, lhs_ops, 0);
       copy_reference_ops_from_ref (lhs, &lhs_ops);
       tem = lhs_ops;
-      lhs_ops = valueize_refs (lhs_ops);
+      lhs_ops = valueize_refs_1 (lhs_ops, &valueized_anything);
       gcc_assert (lhs_ops == tem);
-      lhs_ref_ok = ao_ref_init_from_vn_reference (&lhs_ref, get_alias_set (lhs),
+      if (valueized_anything)
+	{
+	  lhs_ref_ok = ao_ref_init_from_vn_reference (&lhs_ref,
+						      get_alias_set (lhs),
 						      TREE_TYPE (lhs), lhs_ops);
 	  if (lhs_ref_ok
 	      && !refs_may_alias_p_1 (ref, &lhs_ref, true))
 	    return NULL;
 	}
+      else
+	{
+	  ao_ref_init (&lhs_ref, lhs);
+	  lhs_ref_ok = true;
+	}
+    }
 
   base = ao_ref_base (ref);
   offset = ref->offset;
@@ -1469,6 +1479,20 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_)
 	  j--;
 	}
 
+      /* ???  The innermost op should always be a MEM_REF and we already
+         checked that the assignment to the lhs kills vr.  Thus for
+	 aggregate copies using char[] types the vn_reference_op_eq
+	 may fail when comparing types for compatibility.  But we really
+	 don't care here - further lookups with the rewritten operands
+	 will simply fail if we messed up types too badly.  */
+      if (j == 0 && i == 0
+	  && VEC_index (vn_reference_op_s, lhs_ops, 0)->opcode == MEM_REF
+	  && VEC_index (vn_reference_op_s, vr->operands, i)->opcode == MEM_REF
+	  && tree_int_cst_equal
+	       (VEC_index (vn_reference_op_s, lhs_ops, 0)->op0,
+		VEC_index (vn_reference_op_s, vr->operands, i)->op0))
+	i--, j--;
+
       /* i now points to the first additional op.
 	 ???  LHS may not be completely contained in VR, one or more
 	 VIEW_CONVERT_EXPRs could be in its way.  We could at least