args: don't use alloca for const size cases.

* args.h (args_decl_list): This macro now handles only
constant values of N. It declares an anonyous container
struct type which juxtaposes the struc args header
with exactly N values. This is simply defined as a local
variable without alloca.
(args_decl_constsize): Like args_decl, but requiring a
constant N; implemented via args_decl_list.
(args_decl_list_dyn): New name for the old args_decl_list
which calls alloca. No places in the code depend on this
at all, except the definition of args_decl.
(args_decl): Retargeted to args_decl_list_dyn.
There is some inconsistency in the macro naming in that
args_decl_constsize depends on args_decl_list, and
args_decl depends on arg_decl_list_dyn.  This was done
to minimize diffs. Most direct uses of args_decl_list
have a constant size, but a large number of args_decl
uses do not have a constant size.

* eval.c (op_catch): Use args_decl_constsize.

* ffi.c (ffi_struct_in, ffi_struct_get, union_out):
Likewise.

* ftw.c (ftw_callback): Likewise.

* lib.c (funcall, funcall1, funcall2, funcall3,
funcall4, uniq, relate): Likewise.

* socket.c (sockaddr_in_unpack, sockaddr_in6_unpack,
sockaddr_un_unpack):
Likewise.

* stream.c (formatv): Likewise.

* struct.c (struct_from_plist, struct_from_args,
make_struct_lit): Likewise.

* sysif.c (termios_unpack): Likewise.

* time.c (broken_time_struct): Likewise.

1 files changed, 7 insertions, 2 deletions

diff --git a/args.h b/args.h
index 6f4baa43..df8cb3db 100644
--- a/args.h
+++ b/args.h
@@ -64,14 +64,19 @@ INLINE void args_set_fill(struct args *args, cnum fill)
 }
 
 #define args_decl_list(NAME, N, L)                                      \
+  struct { struct args args; val arg[N]; } _ac;                         \
+  struct args *NAME = args_init_list(&_ac.args, N, L)
+
+#define args_decl_constsize(NAME, N) args_decl_list(NAME, N, nil)
+
+#define args_decl_list_dyn(NAME, N, L)                                  \
   mem_t *NAME ## _mem =                                                 \
     coerce(mem_t *,                                                     \
            alloca(offsetof(struct args, arg) + (N)*sizeof (val)));      \
   struct args *NAME = args_init_list(coerce(struct args *,              \
                                             NAME ## _mem), N, L)
 
-#define args_decl(NAME, N) args_decl_list(NAME, N, nil)
-
+#define args_decl(NAME, N) args_decl_list_dyn(NAME, N, nil)
 
 INLINE val args_add(struct args *args, val arg)
 {