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authorAndy Wingo <wingo@pobox.com>2017-09-07 16:55:30 +0200
committerAndy Wingo <wingo@pobox.com>2017-09-14 09:44:33 +0200
commit7e91ff651b3c9f7c27f2be146ea611bab65809a8 (patch)
tree09e2c37c935bf20f3883721d55708529b7e9eebd /libguile/struct.h
parent48989599016c218da68899aee2af8264df98e34c (diff)
downloadguile-7e91ff651b3c9f7c27f2be146ea611bab65809a8.tar.gz
Remove indirection in structs
* libguile/gc.c (scm_storage_prehistory): Register struct displacement here. * libguile/goops.c (scm_sys_modify_instance): Fix the format of a comment. * libguile/modules.c (scm_post_boot_init_modules): Update for new format of struct vtable references. * libguile/struct.c (scm_i_alloc_struct): Update to include slots directly, instead of being indirected by an embedded pointer. (scm_c_make_structv, scm_allocate_struct, scm_i_make_vtable_vtable): Adapt to pass vtable bits as argument to scm_i_alloc_struct, not vtable data bits. (scm_init_struct): Remove two-word displacement from libgc. * libguile/struct.h: Update comment. (SCM_STRUCT_SLOTS, SCM_STRUCT_DATA): Update definitions. (SCM_STRUCT_VTABLE_DATA, SCM_STRUCT_VTABLE_SLOTS): Remove. (SCM_STRUCT_VTABLE, SCM_STRUCT_LAYOUT, SCM_STRUCT_PRINTER) (SCM_STRUCT_FINALIZER, SCM_STRUCT_VTABLE_FLAGS) (SCM_STRUCT_VTABLE_FLAG_IS_SET): Simplify definitions. * module/system/base/types.scm (cell->object, address->inferior-struct): Adapt to struct representation change.
Diffstat (limited to 'libguile/struct.h')
-rw-r--r--libguile/struct.h75
1 files changed, 27 insertions, 48 deletions
diff --git a/libguile/struct.h b/libguile/struct.h
index e7007b7e0..0dfcf4618 100644
--- a/libguile/struct.h
+++ b/libguile/struct.h
@@ -3,7 +3,7 @@
#ifndef SCM_STRUCT_H
#define SCM_STRUCT_H
-/* Copyright (C) 1995,1997,1999,2000,2001, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2015 Free Software Foundation, Inc.
+/* Copyright (C) 1995,1997,1999,2000,2001, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2015, 2017 Free Software Foundation, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
@@ -28,42 +28,28 @@
-/* The relationship between a struct and its vtable is a bit complicated,
- because we want structs to be used as GOOPS' native representation -- which
- in turn means we need support for changing the "class" (vtable) of an
- "instance" (struct). This necessitates some indirection and trickery.
-
- To summarize, structs are laid out this way:
-
- .-------.
- | |
- .----------------+---v------------- -
- | vtable | data | slot0 | slot1 |
- `----------------+----------------- -
- | .-------.
- | | |
- .---v------------+---v------------- -
- | vtable | data | slot0 | slot1 |
- `----------------+----------------- -
- |
- v
+/* Structs are sequences of words where the first word points to the
+ struct's vtable, and the rest are its slots. The vtable indicates
+ how many words are in the struct among other meta-information. A
+ vtable is itself a struct and as such has a vtable, and so on until
+ you get to a root struct that is its own vtable.
+ .--------+----------------- -
+ | vtable | slot0 | slot1 |
+ `--------+----------------- -
+ |
+ |
+ .---v----+----------------- -
+ | vtable | slot0 | slot1 |
+ `--------+----------------- -
+ |
...
- .-------.
- | | |
- .---v------------+---v------------- -
- .-| vtable | data | slot0 | slot1 |
- | `----------------+----------------- -
+ |
+ .---v----+----------------- -
+ .-| vtable | slot0 | slot1 |
+ | `--------+----------------- -
| ^
`-----'
-
- The DATA indirection (which corresponds to `SCM_STRUCT_DATA ()') is necessary
- to implement class redefinition.
-
- For more details, see:
-
- http://wingolog.org/archives/2009/11/09/class-redefinition-in-guile
-
*/
/* All vtables have the following fields. */
@@ -123,10 +109,10 @@
typedef void (*scm_t_struct_finalize) (SCM obj);
#define SCM_STRUCTP(X) (!SCM_IMP(X) && (SCM_TYP3(X) == scm_tc3_struct))
-#define SCM_STRUCT_SLOTS(X) ((SCM*)SCM_CELL_WORD_1 ((X)))
+#define SCM_STRUCT_SLOTS(X) (SCM_CELL_OBJECT_LOC(X, 1))
#define SCM_STRUCT_SLOT_REF(X,I) (SCM_STRUCT_SLOTS (X)[(I)])
#define SCM_STRUCT_SLOT_SET(X,I,V) SCM_STRUCT_SLOTS (X)[(I)]=(V)
-#define SCM_STRUCT_DATA(X) ((scm_t_bits*)SCM_CELL_WORD_1 (X))
+#define SCM_STRUCT_DATA(X) ((scm_t_bits*)SCM_STRUCT_SLOTS (X))
#define SCM_STRUCT_DATA_REF(X,I) (SCM_STRUCT_DATA (X)[(I)])
#define SCM_STRUCT_DATA_SET(X,I,V) SCM_STRUCT_DATA (X)[(I)]=(V)
@@ -145,18 +131,12 @@ typedef void (*scm_t_struct_finalize) (SCM obj);
#define SCM_VTABLE_NAME(X) (SCM_STRUCT_SLOT_REF (X, scm_vtable_index_name))
#define SCM_SET_VTABLE_NAME(X,V) (SCM_STRUCT_SLOT_SET (X, scm_vtable_index_name, V))
-/* Structs hold a pointer to their vtable's data, not the vtable itself. To get
- the vtable we have to do an indirection through the self slot. */
-#define SCM_STRUCT_VTABLE_DATA(X) ((scm_t_bits*)(SCM_CELL_WORD_0 (X) - scm_tc3_struct))
-#define SCM_STRUCT_VTABLE_SLOTS(X) ((SCM*)(SCM_CELL_WORD_0 (X) - scm_tc3_struct))
-#define SCM_STRUCT_VTABLE(X) (SCM_STRUCT_VTABLE_SLOTS(X)[scm_vtable_index_self])
-/* But often we just need to access the vtable's data; we can do that without
- the data->self->data indirection. */
-#define SCM_STRUCT_LAYOUT(X) (SCM_STRUCT_VTABLE_SLOTS (X)[scm_vtable_index_layout])
-#define SCM_STRUCT_PRINTER(X) (SCM_STRUCT_VTABLE_SLOTS (X)[scm_vtable_index_instance_printer])
-#define SCM_STRUCT_FINALIZER(X) ((scm_t_struct_finalize)SCM_STRUCT_VTABLE_DATA (X)[scm_vtable_index_instance_finalize])
-#define SCM_STRUCT_VTABLE_FLAGS(X) (SCM_STRUCT_VTABLE_DATA (X)[scm_vtable_index_flags])
-#define SCM_STRUCT_VTABLE_FLAG_IS_SET(X,F) (SCM_STRUCT_VTABLE_DATA (X)[scm_vtable_index_flags]&(F))
+#define SCM_STRUCT_VTABLE(X) (SCM_PACK (SCM_CELL_WORD_0 (X) - scm_tc3_struct))
+#define SCM_STRUCT_LAYOUT(X) (SCM_VTABLE_LAYOUT (SCM_STRUCT_VTABLE (X)))
+#define SCM_STRUCT_PRINTER(X) (SCM_VTABLE_INSTANCE_PRINTER (SCM_STRUCT_VTABLE (X)))
+#define SCM_STRUCT_FINALIZER(X) (SCM_VTABLE_INSTANCE_FINALIZER (SCM_STRUCT_VTABLE (X)))
+#define SCM_STRUCT_VTABLE_FLAGS(X) (SCM_VTABLE_FLAGS (SCM_STRUCT_VTABLE (X)))
+#define SCM_STRUCT_VTABLE_FLAG_IS_SET(X,F) (SCM_VTABLE_FLAG_IS_SET (SCM_STRUCT_VTABLE (X), (F)))
#define SCM_STRUCT_APPLICABLE_P(X) (SCM_STRUCT_VTABLE_FLAG_IS_SET ((X), SCM_VTABLE_FLAG_APPLICABLE))
#define SCM_STRUCT_SETTER_P(X) (SCM_STRUCT_VTABLE_FLAG_IS_SET ((X), SCM_VTABLE_FLAG_SETTER))
@@ -191,7 +171,6 @@ SCM_API void scm_print_struct (SCM exp, SCM port, scm_print_state *);
SCM_INTERNAL SCM scm_i_struct_equalp (SCM s1, SCM s2);
SCM_INTERNAL unsigned long scm_struct_ihashq (SCM, unsigned long, void *);
-SCM_INTERNAL SCM scm_i_alloc_struct (scm_t_bits *vtable_data, int n_words);
SCM_INTERNAL void scm_i_struct_inherit_vtable_magic (SCM vtable, SCM obj);
SCM_INTERNAL void scm_init_struct (void);