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-rw-r--r--includes/rts/storage/InfoTables.h13
1 files changed, 12 insertions, 1 deletions
diff --git a/includes/rts/storage/InfoTables.h b/includes/rts/storage/InfoTables.h
index fb14ac5821..bb1bac0c65 100644
--- a/includes/rts/storage/InfoTables.h
+++ b/includes/rts/storage/InfoTables.h
@@ -223,10 +223,21 @@ typedef struct StgInfoTable_ {
them doesn't affect the layout).
- If srt_bitmap (in the std info table part) is zero, then the srt
- field may be omitted. This only applies if the slow_apply and
+ field needn't be set. This only applies if the slow_apply and
bitmap fields have also been omitted.
-------------------------------------------------------------------------- */
+/*
+ Note [Encoding static reference tables]
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ As static reference tables appear frequently in code, we use a special
+ compact encoding for the common case of a module defining only a few CAFs: We
+ produce one table containing a list of CAFs in the module and then include a
+ bitmap in each info table describing which entries of this table the closure
+ references.
+ */
+
typedef struct StgFunInfoExtraRev_ {
OFFSET_FIELD(slow_apply_offset); /* apply to args on the stack */
union {