revert: builtins.c (fold_builtin_memory_op): Use the alias oracle to query if the memory regions for memmove overlap.

2009-09-02  Richard Guenther  <rguenther@suse.de>

        Revert
        2009-08-31  Richard Guenther  <rguenther@suse.de>

        * builtins.c (fold_builtin_memory_op): Use the alias oracle
        to query if the memory regions for memmove overlap.
        * tree-ssa-alias.c (ptr_deref_may_alias_decl_p): Relax the
        asserts on pointers, instead deal with odd trees.
        (ptr_derefs_may_alias_p): Likewise.
        (refs_may_alias_p_1): Constructor bases also never alias.

From-SVN: r151320

1 files changed, 51 insertions, 7 deletions

diff --git a/gcc/builtins.c b/gcc/builtins.c
index 7ea899d..b657275 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -8990,8 +8990,6 @@ fold_builtin_memory_op (location_t loc, tree dest, tree src,
 
       if (endp == 3)
 	{
-	  ao_ref srcref, destref;
-
 	  src_align = get_pointer_alignment (src, BIGGEST_ALIGNMENT);
 	  dest_align = get_pointer_alignment (dest, BIGGEST_ALIGNMENT);
 
@@ -9014,16 +9012,62 @@ fold_builtin_memory_op (location_t loc, tree dest, tree src,
 	    }
 
 	  /* If *src and *dest can't overlap, optimize into memcpy as well.  */
-	  ao_ref_init_from_ptr_and_size (&srcref, src, len);
-	  ao_ref_init_from_ptr_and_size (&destref, dest, len);
-	  if (!refs_may_alias_p_1 (&srcref, &destref, false))
+	  srcvar = build_fold_indirect_ref_loc (loc, src);
+	  destvar = build_fold_indirect_ref_loc (loc, dest);
+	  if (srcvar
+	      && !TREE_THIS_VOLATILE (srcvar)
+	      && destvar
+	      && !TREE_THIS_VOLATILE (destvar))
 	    {
-	      tree fn = implicit_built_in_decls[BUILT_IN_MEMCPY];
+	      tree src_base, dest_base, fn;
+	      HOST_WIDE_INT src_offset = 0, dest_offset = 0;
+	      HOST_WIDE_INT size = -1;
+	      HOST_WIDE_INT maxsize = -1;
+
+	      src_base = srcvar;
+	      if (handled_component_p (src_base))
+		src_base = get_ref_base_and_extent (src_base, &src_offset,
+						    &size, &maxsize);
+	      dest_base = destvar;
+	      if (handled_component_p (dest_base))
+		dest_base = get_ref_base_and_extent (dest_base, &dest_offset,
+						     &size, &maxsize);
+	      if (host_integerp (len, 1))
+		{
+		  maxsize = tree_low_cst (len, 1);
+		  if (maxsize
+		      > INTTYPE_MAXIMUM (HOST_WIDE_INT) / BITS_PER_UNIT)
+		    maxsize = -1;
+		  else
+		    maxsize *= BITS_PER_UNIT;
+		}
+	      else
+		maxsize = -1;
+	      if (SSA_VAR_P (src_base)
+		  && SSA_VAR_P (dest_base))
+		{
+		  if (operand_equal_p (src_base, dest_base, 0)
+		      && ranges_overlap_p (src_offset, maxsize,
+					   dest_offset, maxsize))
+		    return NULL_TREE;
+		}
+	      else if (TREE_CODE (src_base) == INDIRECT_REF
+		       && TREE_CODE (dest_base) == INDIRECT_REF)
+		{
+		  if (! operand_equal_p (TREE_OPERAND (src_base, 0),
+					 TREE_OPERAND (dest_base, 0), 0)
+		      || ranges_overlap_p (src_offset, maxsize,
+					   dest_offset, maxsize))
+		    return NULL_TREE;
+		}
+	      else
+		return NULL_TREE;
+
+	      fn = implicit_built_in_decls[BUILT_IN_MEMCPY];
 	      if (!fn)
 		return NULL_TREE;
 	      return build_call_expr_loc (loc, fn, 3, dest, src, len);
 	    }
-
 	  return NULL_TREE;
 	}