+ arg1 = TREE_VALUE (arglist);
+ arg2 = TREE_VALUE (TREE_CHAIN (arglist));
+ len = TREE_VALUE (TREE_CHAIN (TREE_CHAIN (arglist)));
+
+ /* If the len parameter is zero, return zero. */
+ if (host_integerp (len, 1) && tree_low_cst (len, 1) == 0)
+ {
+ /* Evaluate and ignore arg1 and arg2 in case they have
+ side-effects. */
+ expand_expr (arg1, const0_rtx, VOIDmode, EXPAND_NORMAL);
+ expand_expr (arg2, const0_rtx, VOIDmode, EXPAND_NORMAL);
+ return const0_rtx;
+ }
+
+ /* If len parameter is one, return an expression corresponding to
+ (*(const unsigned char*)arg1 - (const unsigned char*)arg2). */
+ if (host_integerp (len, 1) && tree_low_cst (len, 1) == 1)
+ {
+ tree cst_uchar_node = build_type_variant (unsigned_char_type_node, 1, 0);
+ tree cst_uchar_ptr_node = build_pointer_type (cst_uchar_node);
+ tree ind1 =
+ fold (build1 (CONVERT_EXPR, integer_type_node,
+ build1 (INDIRECT_REF, cst_uchar_node,
+ build1 (NOP_EXPR, cst_uchar_ptr_node, arg1))));
+ tree ind2 =
+ fold (build1 (CONVERT_EXPR, integer_type_node,
+ build1 (INDIRECT_REF, cst_uchar_node,
+ build1 (NOP_EXPR, cst_uchar_ptr_node, arg2))));
+ tree result = fold (build (MINUS_EXPR, integer_type_node, ind1, ind2));
+ return expand_expr (result, target, mode, EXPAND_NORMAL);
+ }
+
+#ifdef HAVE_cmpstrsi