New API for more optimal usage of GC_calloc_explicitly_typed

If the client needs to allocate many typed object arrays of same
layout and amount of elements, then "calloc" descriptor could be
created once (by GC_calloc_prepare_explicitly_typed) followed by
multiple allocations (by GC_calloc_do_explicitly_typed) referring
to the same descriptor.

* include/gc/gc_typed.h (GC_CALLOC_TYPED_DESCR_WORDS): New macro.
* include/gc/gc_typed.h (GC_calloc_typed_descr_s): New struct type.
* include/gc/gc_typed.h (GC_calloc_prepare_explicitly_typed,
GC_calloc_do_explicitly_typed): New function declaration.
* tests/gctest.c [!NO_TYPED_TEST && !GC_DEBUG] (typed_test): Define
ctd_l local variable; call GC_calloc_prepare_explicitly_typed() before
loop; call GC_calloc_do_explicitly_typed() instead of
GC_CALLOC_EXPLICITLY_TYPED(1001).
* typd_mlc.c (GC_calloc_typed_descr_s.alloc_lb): Change type from
size_t to word.
* typd_mlc.c (GC_calloc_typed_descr_s.descr_type): Change type from int
to signed_word.
* typd_mlc.c (GC_calloc_prepare_explicitly_typed,
GC_calloc_do_explicitly_typed): Change from STATIC to GC_API; add
ctd_sz argument; check ctd_sz in assertion; add casts for alloc_lb
field.
* typd_mlc.c (GC_calloc_prepare_explicitly_typed): Add static assertion
about size of GC_calloc_typed_descr_s and GC_CALLOC_TYPED_DESCR_WORDS;
change return type from void to it.
* typd_mlc.c (GC_calloc_explicitly_typed): Pass sizeof(ctd) to
GC_calloc_prepare_explicitly_typed(), GC_calloc_do_explicitly_typed().

1 files changed, 31 insertions, 0 deletions

diff --git a/include/gc/gc_typed.h b/include/gc/gc_typed.h
index 1de355fe..a9a82931 100644
--- a/include/gc/gc_typed.h
+++ b/include/gc/gc_typed.h
@@ -104,6 +104,37 @@ GC_API GC_ATTR_MALLOC GC_ATTR_CALLOC_SIZE(1, 2) void * GC_CALL
         /* bitmap of d multiplied by sizeof GC_word.            */
         /* Returned object is cleared.                          */
 
+#define GC_CALLOC_TYPED_DESCR_WORDS 8
+
+#ifdef GC_BUILD
+  struct GC_calloc_typed_descr_s;
+#else
+  struct GC_calloc_typed_descr_s {
+    GC_word opaque[GC_CALLOC_TYPED_DESCR_WORDS];
+  };
+#endif
+
+GC_API int GC_CALL GC_calloc_prepare_explicitly_typed(
+                        struct GC_calloc_typed_descr_s * /* pctd */,
+                        size_t /* sizeof_ctd */, size_t /* nelements */,
+                        size_t /* element_size_in_bytes */, GC_descr);
+        /* This is same as GC_calloc_explicitly_typed but more optimal  */
+        /* in terms of the performance and memory usage if the client   */
+        /* needs to allocate multiple typed object arrays with the      */
+        /* same layout and number of elements.  The client should call  */
+        /* it to be prepared for the subsequent allocations by          */
+        /* GC_calloc_do_explicitly_typed, one or many.  The result of   */
+        /* the preparation is stored to *pctd, even in case of          */
+        /* a failure.  The prepared structure could be just dropped     */
+        /* when no longer needed.  Returns 0 on failure, 1 on success;  */
+        /* the result could be ignored (as it is also stored to *pctd   */
+        /* and checked later by GC_calloc_do_explicitly_typed).         */
+
+GC_API GC_ATTR_MALLOC void * GC_CALL GC_calloc_do_explicitly_typed(
+                        const struct GC_calloc_typed_descr_s * /* pctd */,
+                        size_t /* sizeof_ctd */);
+        /* The actual object allocation for the prepared description.   */
+
 #ifdef GC_DEBUG
 # define GC_MALLOC_EXPLICITLY_TYPED(bytes, d) ((void)(d), GC_MALLOC(bytes))
 # define GC_MALLOC_EXPLICITLY_TYPED_IGNORE_OFF_PAGE(bytes, d) \