apply: eliminate wasteful consing.

Now (pprof (apply '+ 1 2 3 4 5 '(6 7))) shows zero
bytes consed. Previously 176 (on 32 bit). This is
the same whether the expression is compiled or
interpreted.

* eval.c (applyv): Rewritten to efficiently manipulate the
args and call generic_funcall directly. The consing
funcction apply_intrinsic_frob_args is only used when
args contains a trailing list (args->list) and is only
used on that trailing list, not the entire arg list.
Also, changing the static function to external.

* eval.h (applyv): Declared.

* vm.c (vm_apply): Use applyv instead of wastefully
converting the arguments to a consed list and going through
apply_intrinsic.

1 files changed, 12 insertions, 2 deletions

diff --git a/eval.c b/eval.c
index c98625a8..1ff89af2 100644
--- a/eval.c
+++ b/eval.c
@@ -1142,9 +1142,19 @@ val apply_intrinsic(val fun, val args)
   return apply(fun, apply_intrinsic_frob_args(z(args)));
 }
 
-static val applyv(val fun, struct args *args)
+val applyv(val fun, struct args *args)
 {
-  return apply_intrinsic(fun, args_get_list(args));
+  args_normalize_least(args, 1);
+
+  if (!args->fill)
+    uw_throwf(error_s, lit("apply: trailing-args argument missing"), nao);
+
+  if (!args->list)
+    args->list = z(args->arg[--args->fill]);
+  else
+    args->list = apply_intrinsic_frob_args(args->list);
+
+  return generic_funcall(fun, args);
 }
 
 static loc term(loc head)