Implement the Named Return Value optimization.

        * c-common.h (RETURN_NULLIFIED_P): New macro.
        * c-semantics.c (genrtl_return_stmt): Check it.
        * cp-tree.h (struct cp_language_function): Add x_return_value.
        (current_function_return_value): Now a macro.
        * decl.c: Don't define it.
        (define_label, finish_case_label): Don't clear it.
        (init_decl_processing): Don't register it with GC.
        * semantics.c (genrtl_finish_function): Don't check it for
        no_return_label.  Copy the RTL from the return value to
        current_function_return_value and walk, calling...
        (nullify_returns_r): ...this new fn.
        * typeck.c (check_return_expr): Set current_function_return_value.

        * expr.c (clear_storage): Set TREE_NOTHROW on the decl for memset.
        (emit_block_move): Likewise.

From-SVN: r43445

1 files changed, 4 insertions, 2 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index 230cf9f..9b81988 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -1773,6 +1773,7 @@ emit_block_move (x, y, size, align)
 	  DECL_EXTERNAL (fn) = 1;
 	  TREE_PUBLIC (fn) = 1;
 	  DECL_ARTIFICIAL (fn) = 1;
+	  TREE_NOTHROW (fn) = 1;
 	  make_decl_rtl (fn, NULL);
 	  assemble_external (fn);
 	}
@@ -2659,7 +2660,7 @@ clear_storage (object, size, align)
 
 	     For targets where libcalls and normal calls have different
 	     conventions for returning pointers, we could end up generating
-	      incorrect code.
+	     incorrect code.
 
 	     So instead of using a libcall sequence we build up a suitable
 	     CALL_EXPR and expand the call in the normal fashion.  */
@@ -2677,6 +2678,7 @@ clear_storage (object, size, align)
 	      DECL_EXTERNAL (fn) = 1;
 	      TREE_PUBLIC (fn) = 1;
 	      DECL_ARTIFICIAL (fn) = 1;
+	      TREE_NOTHROW (fn) = 1;
 	      make_decl_rtl (fn, NULL);
 	      assemble_external (fn);
 	    }
@@ -4547,7 +4549,7 @@ store_constructor (exp, target, align, cleared, size)
 
       /* If the constructor has fewer fields than the structure
 	 or if we are initializing the structure to mostly zeros,
-	 clear the whole structure first.  Don't do this is TARGET is
+	 clear the whole structure first.  Don't do this if TARGET is a
 	 register whose mode size isn't equal to SIZE since clear_storage
 	 can't handle this case.  */
       else if (size > 0