wingo pushed a commit to branch wip-whippet
in repository guile.
commit 8141c35ec4d5e9eb6901a7ffd244984a6a7101a0
Author: Andy Wingo <wi...@pobox.com>
AuthorDate: Fri Jun 20 14:22:52 2025 +0200
Change to not inline scm_cell / scm_double_cell / scm_words
* libguile/gc-malloc.c (scm_cell):
(scm_double_cell):
(scm_words): Implement here.
* libguile/gc.h:
* libguile/inline.c: Not here.
---
libguile/gc-malloc.c | 50 ++++++++++++++++++++++++++
libguile/gc.h | 100 +++------------------------------------------------
libguile/inline.c | 1 -
3 files changed, 54 insertions(+), 97 deletions(-)
diff --git a/libguile/gc-malloc.c b/libguile/gc-malloc.c
index 30a8ad089..647d391df 100644
--- a/libguile/gc-malloc.c
+++ b/libguile/gc-malloc.c
@@ -207,3 +207,53 @@ scm_gc_strdup (const char *str, const char *what)
{
return scm_gc_strndup (str, strlen (str), what);
}
+
+SCM
+scm_cell (scm_t_bits car, scm_t_bits cdr)
+{
+ scm_t_bits *words = scm_allocate_sloppy (SCM_I_CURRENT_THREAD,
+ sizeof (scm_t_bits) * 2);
+
+ words[0] = car;
+ words[1] = cdr;
+
+ /* Probably the user isn't accessing the object as a "scm_t_bits*", and
+ in standard C that would allow the compiler to treat the above
+ writes as not aliasing the "struct scm_pair" or whatever that the
+ user actually wants, which can result in correctness-breaking
+ optimizations. Therefore Guile compiles with -fno-strict-aliasing,
+ and doesn't expose this function for inlining. It would be nice if
+ Guile could be written in fully standard C, but that's not where
+ we're at right now. */
+
+ return SCM_PACK_POINTER (words);
+}
+
+SCM
+scm_double_cell (scm_t_bits car, scm_t_bits cbr,
+ scm_t_bits ccr, scm_t_bits cdr)
+{
+ scm_t_bits *words = scm_allocate_sloppy (SCM_I_CURRENT_THREAD,
+ sizeof (scm_t_bits) * 4);
+
+ words[0] = car;
+ words[1] = cbr;
+ words[2] = ccr;
+ words[3] = cdr;
+
+ /* See above notes about strict aliasing. */
+
+ return SCM_PACK_POINTER (words);
+}
+
+SCM
+scm_words (scm_t_bits car, uint32_t n_words)
+{
+ scm_t_bits *words = scm_allocate_sloppy (SCM_I_CURRENT_THREAD,
+ sizeof (scm_t_bits) * n_words);
+ words[0] = car;
+
+ /* See above notes about strict aliasing. */
+
+ return SCM_PACK_POINTER (words);
+}
diff --git a/libguile/gc.h b/libguile/gc.h
index 91da59946..34717f2f6 100644
--- a/libguile/gc.h
+++ b/libguile/gc.h
@@ -142,102 +142,10 @@ SCM_API char *scm_gc_strndup (const char *str, size_t n,
const char *what)
#define SCM_GC_MALLOC_POINTERLESS(size) scm_gc_malloc_pointerless (size, NULL)
-SCM_INLINE SCM scm_cell (scm_t_bits car, scm_t_bits cdr);
-SCM_INLINE SCM scm_double_cell (scm_t_bits car, scm_t_bits cbr,
- scm_t_bits ccr, scm_t_bits cdr);
-SCM_INLINE SCM scm_words (scm_t_bits car, uint32_t n_words);
-
-#if SCM_CAN_INLINE || defined SCM_INLINE_C_IMPLEMENTING_INLINES
-
-SCM_INLINE_IMPLEMENTATION SCM
-scm_cell (scm_t_bits car, scm_t_bits cdr)
-{
- SCM cell = SCM_PACK_POINTER (SCM_GC_MALLOC (sizeof (scm_t_cell)));
-
- /* Initialize the type slot last so that the cell is ignored by the GC
- until it is completely initialized. This is only relevant when the GC
- can actually run during this code, which it can't since the GC only runs
- when all other threads are stopped. */
- SCM_GC_SET_CELL_WORD (cell, 1, cdr);
- SCM_GC_SET_CELL_WORD (cell, 0, car);
-
- return cell;
-}
-
-SCM_INLINE_IMPLEMENTATION SCM
-scm_double_cell (scm_t_bits car, scm_t_bits cbr,
- scm_t_bits ccr, scm_t_bits cdr)
-{
- SCM z;
-
- z = SCM_PACK_POINTER (SCM_GC_MALLOC (2 * sizeof (scm_t_cell)));
- /* Initialize the type slot last so that the cell is ignored by the
- GC until it is completely initialized. This is only relevant
- when the GC can actually run during this code, which it can't
- since the GC only runs when all other threads are stopped.
- */
- SCM_GC_SET_CELL_WORD (z, 1, cbr);
- SCM_GC_SET_CELL_WORD (z, 2, ccr);
- SCM_GC_SET_CELL_WORD (z, 3, cdr);
- SCM_GC_SET_CELL_WORD (z, 0, car);
-
- /* When this function is inlined, it's possible that the last
- SCM_GC_SET_CELL_WORD above will be adjacent to a following
- initialization of z. E.g., it occurred in scm_make_real. GCC
- from around version 3 (e.g., certainly 3.2) began taking
- advantage of strict C aliasing rules which say that it's OK to
- interchange the initialization above and the one below when the
- pointer types appear to differ sufficiently. We don't want that,
- of course. GCC allows this behavior to be disabled with the
- -fno-strict-aliasing option, but would also need to be supplied
- by Guile users. Instead, the following statements prevent the
- reordering.
- */
-#ifdef __GNUC__
- __asm__ volatile ("" : : : "memory");
-#else
- /* portable version, just in case any other compiler does the same
- thing. */
- scm_remember_upto_here_1 (z);
-#endif
-
- return z;
-}
-
-SCM_INLINE_IMPLEMENTATION SCM
-scm_words (scm_t_bits car, uint32_t n_words)
-{
- SCM z;
-
- z = SCM_PACK_POINTER (SCM_GC_MALLOC (sizeof (scm_t_bits) * n_words));
- SCM_GC_SET_CELL_WORD (z, 0, car);
-
- /* FIXME: is the following concern even relevant with BDW-GC? */
-
- /* When this function is inlined, it's possible that the last
- SCM_GC_SET_CELL_WORD above will be adjacent to a following
- initialization of z. E.g., it occurred in scm_make_real. GCC
- from around version 3 (e.g., certainly 3.2) began taking
- advantage of strict C aliasing rules which say that it's OK to
- interchange the initialization above and the one below when the
- pointer types appear to differ sufficiently. We don't want that,
- of course. GCC allows this behavior to be disabled with the
- -fno-strict-aliasing option, but would also need to be supplied
- by Guile users. Instead, the following statements prevent the
- reordering.
- */
-#ifdef __GNUC__
- __asm__ volatile ("" : : : "memory");
-#else
- /* portable version, just in case any other compiler does the same
- thing. */
- scm_remember_upto_here_1 (z);
-#endif
-
- return z;
-}
-
-#endif /* SCM_CAN_INLINE || defined SCM_INLINE_C_IMPLEMENTING_INLINES */
+SCM scm_cell (scm_t_bits car, scm_t_bits cdr);
+SCM scm_double_cell (scm_t_bits car, scm_t_bits cbr,
+ scm_t_bits ccr, scm_t_bits cdr);
+SCM scm_words (scm_t_bits car, uint32_t n_words);
SCM_API void scm_remember_upto_here_1 (SCM obj);
SCM_API void scm_remember_upto_here_2 (SCM obj1, SCM obj2);
diff --git a/libguile/inline.c b/libguile/inline.c
index 8796e9712..4e71481cf 100644
--- a/libguile/inline.c
+++ b/libguile/inline.c
@@ -26,7 +26,6 @@
#include "array-handle.h"
#include "chars.h"
-#include "gc.h"
#include "pairs.h"
#include "ports.h"
#include "strings.h"
