Hi all, Now that #1173 has been fixed, I would like to simplify the garbage collection code dealing with the symbols.
This mail is a bit long, so I'm adding sections to make it easier to digest. == Problems with the current symbol GC The current code is quite tricky and hard to understand: - It uses a fixed-size "open coded" (if that's the term) hash table, which means sometimes a symbol won't end up in the table at all due to too many collisions. This also means memory use is unbounded, more or less: symbols not in the table are always kept. - There's some randomisation involved, which makes bugs hard to track, because of the fixed table size: on some runs, a symbol will end up in the table, making it eligible for collection, on other runs it won't because the random factor has changed. - The code uses type punning to squeeze a counter into the low bits of a pointer. This is extremely clever, but also tricky. - Because the ordering of symbols and their buckets is indeterminate, some symbols will be collected differently than others, making it yet harder to understand: the symbol is only entered in the table when its bucket is encountered, but if the symbol itself is encoutered while it's in the table, its counter will be incremented. If the symbol is encountered first, it won't increment any counter but when we see the bucket, it will saturate the counter (WTF!) because the symbol is already forwarded. I spent a lot of time thinking the bug for #1173 was here. - The forwarding pointer resolution code is very tricky, especially now with the fix for #1173. Besides all these things, the fixed table size will mean only up to 997 symbols can be collected on each major GC. So, there's a slowdown if there are many symbols. It will needlessly copy unreferenced symbols around during GC. == First patch: simplify GC The attached patch (0001) replaces the weak table with a simpler system: We now keep track of whether a symbol is supposed to be kept around, by making "set!" (or "define") and the plist manipulation procedures smarter. When a symbol has a global definition or a non-empty plist, it *must* stick around, so we change its bucket, to indicate this! Symbols that are disposable will be stored in a "weak" symbol table bucket. Symbols that must stick around will be stored in a "strong" bucket. This way, we can rely on the standard tracing of our GC: For a weak bucket, the GC doesn't mark its symbol. So, the symbol can be collected unless there's another reference to it. For a strong bucket, we simply mark its symbol, so it will stay. At the end of a major or reallocating GC, we walk the symbol tables, and update all weak bucket symbol pointers by dereferencing forwarding pointers. If we see a weak bucket with a symbol that wasn't copied to the target heap area, that symbol was collected, and the bucket can be removed from the chain. Statically allocated symbols are always kept. There's one weird part about the implementation: it sets the bucket's header for weak symbols (C_BUCKET_TYPE | C_SPECIALBLOCK_BIT) in order to have the GC skip the first slot (which is the symbol). Ideally, I'd like to use another bit to indicate that it's a weak reference, but we're all out of special bits! I also updated the symbol GC test: it now has zero tolerance for symbols that are kept around. This works, because symbol tracking is now precise. The test is fully enabled again and can fail the entire test suite, because there's no hash table randomisation factor anymore that can screw things up. == Second patch: making symbol GC optional The second patch is very straightforward: it simply removes the -:w option, making symbol GC the default. There's a diff hunk for the update_symbol_tables() function, but that's reindentation due to a removed if() check. There is no reason why we should let symbol GC be optional. The Ruby community has also had a similar transition to enable GC of symbols, mostly because an attacker could initiate a resource consumption attack by generating lots and lots of large symbols, which would never be cleaned up, eating more and more memory. But regardless of that, the overhead of copying unused symbols is unnecessary, so GCing the symbols should almost always be faster. To check this, I ran the benchmarks again. See the attached "benchmark.diff", which shows the difference between plain CHICKEN 5 [1], CHICKEN 5 with -:w [2] and CHICKEN 5 with these patches [3]. As you can see, [3] is fastest in most situations. Especially the "knucleotide" benchmark really benefits from this patch, as it generates a lot of symbols. It also uses less memory with the patch than without (8.4 MB versus 5.7 MB). Overall, in my benchmark runs, I saw a difference of a minute less spent in major GC time (over 10 minutes in total). I hope this all makes sense. If you need more info about why and how, let me know and I'll try to explain. The patches themselves also have extensive commit messages to explain what they do, and I've tried to add comments here and there to clarify some more. Cheers, Peter
From 7dbad6b6e02443ea3a214ba56b82f2920d519519 Mon Sep 17 00:00:00 2001
From: Peter Bex <pe...@more-magic.net>
Date: Sat, 3 Sep 2016 17:00:41 +0200
Subject: [PATCH 1/3] Simplify and improve reclaimability of symbol GC
Instead of using a secondary symbol table ("weak table") for tracking
unreferenced symbols, we change the symbol's buckets to either hold the
symbol strongly or weakly. This allows us to rely on the GC's normal
function to copy or discard unused symbols.
On minor GC, we *always* copy the symbols, ignoring its bucket's
weak/strong status. This is for performance reasons.
After a major or reallocating GC, we traverse the symbol table and
update the pointers in weak buckets: if the new location of the symbol
is in the tospace/new heap, it must be live, so we keep it and update
the bucket's pointer. Otherwise, we can drop the bucket.
This requires one change to how symbols are managed: when a bucket is
allocated, it is weak by default. When a symbol becomes globally bound
or gains a plist, we change the bucket type from weak to strong. If the
plist is emptied, the bucket type is changed to weak again (but only if
it isn't also globally bound).
Currently we don't support unbinding a symbol, but if we ever do we'll
need to call unpersist on the symbol as well.
There are several advantages to this:
1) It is simpler than the tricky weak table code (see also #1173).
2) Now, all symbols can be collected instead of an upper limit of 997.
3) It is much faster when a lot of discardable symbols are generated.
4) Memory usage is no longer unbounded when many symbols are generated.
Points 3 and 4 are related to point 2. See the knucleotide benchmark
for an extreme example of this: it uses about half as much memory and
is twice as fast under the new implementation.
---
NEWS | 2 +
chicken.h | 15 ++-
eval.scm | 1 +
library.scm | 11 +-
runtime.c | 279 ++++++++++++++++++++++-------------------------
tests/runtests.bat | 3 +-
tests/runtests.sh | 3 +-
tests/symbolgc-tests.scm | 39 ++++---
8 files changed, 179 insertions(+), 174 deletions(-)
diff --git a/NEWS b/NEWS
index ec0dd93..34ec4bc 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,8 @@
provide the desired performance.
- Port directionality has been generalized from a simple input/output
flag to a bitmap, to allow for multidirectional ports.
+ - Weak symbol GC is faster, simpler, and can now collect all
+ unreferenced symbols instead of a maximum of 997 per major GC.
- Compiler
- Fixed an off by one allocation problem in generated C code for (list ...).
diff --git a/chicken.h b/chicken.h
index 3ecdd39..2cd705b 100644
--- a/chicken.h
+++ b/chicken.h
@@ -537,6 +537,8 @@ static inline int isinf_ld (long double x)
/* Fixed size types have pre-computed header tags */
#define C_PAIR_TAG (C_PAIR_TYPE | (C_SIZEOF_PAIR - 1))
#define C_POINTER_TAG (C_POINTER_TYPE | (C_SIZEOF_POINTER - 1))
+#define C_BUCKET_TAG (C_BUCKET_TYPE | (C_SIZEOF_BUCKET - 1))
+#define C_WEAK_BUCKET_TAG (C_BUCKET_TAG | C_SPECIALBLOCK_BIT)
#define C_LOCATIVE_TAG (C_LOCATIVE_TYPE | (C_SIZEOF_LOCATIVE - 1))
#define C_TAGGED_POINTER_TAG (C_TAGGED_POINTER_TYPE | (C_SIZEOF_TAGGED_POINTER - 1))
#define C_SYMBOL_TAG (C_SYMBOL_TYPE | (C_SIZEOF_SYMBOL - 1))
@@ -1052,6 +1054,7 @@ typedef void (C_ccall *C_proc)(C_word, C_word *) C_noret;
#define C_bignum_size(b) (C_bytestowords(C_header_size(C_internal_bignum_vector(b)))-1)
#define C_make_header(type, size) ((C_header)(((type) & C_HEADER_BITS_MASK) | ((size) & C_HEADER_SIZE_MASK)))
#define C_symbol_value(x) (C_block_item(x, 0))
+#define C_symbol_plist(x) (C_block_item(x, 2))
#define C_save(x) (*(--C_temporary_stack) = (C_word)(x))
#define C_rescue(x, i) (C_temporary_stack[ i ] = (x))
#define C_restore (*(C_temporary_stack++))
@@ -2136,6 +2139,8 @@ C_fctexport C_word C_fcall C_a_i_flonum_gcd(C_word **p, C_word n, C_word x, C_wo
C_fctexport C_word C_fcall C_i_getprop(C_word sym, C_word prop, C_word def) C_regparm;
C_fctexport C_word C_fcall C_putprop(C_word **a, C_word sym, C_word prop, C_word val) C_regparm;
+C_fctexport C_word C_fcall C_i_persist_symbol(C_word sym) C_regparm;
+C_fctexport C_word C_fcall C_i_unpersist_symbol(C_word sym) C_regparm;
C_fctexport C_word C_fcall C_i_get_keyword(C_word key, C_word args, C_word def) C_regparm;
C_fctexport C_u64 C_fcall C_milliseconds(void) C_regparm;
C_fctexport C_u64 C_fcall C_cpu_milliseconds(void) C_regparm;
@@ -2772,6 +2777,14 @@ C_inline C_word C_i_symbolp(C_word x)
return C_mk_bool(!C_immediatep(x) && C_block_header(x) == C_SYMBOL_TAG);
}
+C_inline int C_persistable_symbol(C_word x)
+{
+ C_word val = C_symbol_value(x);
+ /* Symbol is bound (and not a keyword), or has a non-empty plist */
+ return (!C_enable_gcweak || /* Overrides to always true */
+ (val != C_SCHEME_UNBOUND && val != x) ||
+ C_symbol_plist(x) != C_SCHEME_END_OF_LIST);
+}
C_inline C_word C_i_pairp(C_word x)
{
@@ -3409,7 +3422,7 @@ C_inline C_word C_fcall C_a_bucket(C_word **ptr, C_word head, C_word tail)
{
C_word *p = *ptr, *p0 = p;
- *(p++) = C_BUCKET_TYPE | (C_SIZEOF_BUCKET - 1);
+ *(p++) = C_enable_gcweak ? C_WEAK_BUCKET_TAG : C_BUCKET_TAG;
*(p++) = head;
*(p++) = tail;
*ptr = p;
diff --git a/eval.scm b/eval.scm
index 7ee369a..61d7f48 100644
--- a/eval.scm
+++ b/eval.scm
@@ -389,6 +389,7 @@
(lambda (v)
(##sys#error 'eval "environment is not mutable" evalenv var)) ;XXX var?
(lambda (v)
+ (##sys#persist-symbol var)
(##sys#setslot var 0 (##core#app val v))) ) ) ]
[(zero? i) (lambda (v) (##sys#setslot (##sys#slot v 0) j (##core#app val v)))]
[else
diff --git a/library.scm b/library.scm
index 246f70f..5c9387f 100644
--- a/library.scm
+++ b/library.scm
@@ -250,6 +250,7 @@ EOF
(define ##sys#gc (##core#primitive "C_gc"))
(define (##sys#setslot x i y) (##core#inline "C_i_setslot" x i y))
(define (##sys#setislot x i y) (##core#inline "C_i_set_i_slot" x i y))
+(define (##sys#persist-symbol s) (##core#inline "C_i_persist_symbol" s))
(define ##sys#allocate-vector (##core#primitive "C_allocate_vector"))
(define (argc+argv) (##sys#values main_argc main_argv))
(define ##sys#make-structure (##core#primitive "C_make_structure"))
@@ -5704,7 +5705,10 @@ EOF
(##sys#setslot ptl 1 nxt)
(##sys#setslot sym 2 nxt) )
#t ) )
- (loop nxt tl) ) ) ) ) )
+ (loop nxt tl) ) ) ) )
+ (when (null? (##sys#slot sym 2))
+ ;; This will only unpersist if symbol is also unbound
+ (##core#inline "C_i_unpersist_symbol" sym) ) )
(define symbol-plist
(getter-with-setter
@@ -5718,7 +5722,10 @@ EOF
(##sys#setslot sym 2 lst)
(##sys#signal-hook
#:type-error "property-list must be of even length"
- lst sym)))
+ lst sym))
+ (if (null? lst)
+ (##core#inline "C_i_unpersist_symbol" sym)
+ (##core#inline "C_i_persist_symbol" sym)))
"(symbol-plist sym)"))
(define (get-properties sym props)
diff --git a/runtime.c b/runtime.c
index 6a50c06..14732bf 100644
--- a/runtime.c
+++ b/runtime.c
@@ -167,12 +167,6 @@ static C_TLS int timezone;
#define MAX_HASH_PREFIX 64
-#define WEAK_TABLE_SIZE 997
-#define WEAK_HASH_ITERATIONS 4
-#define WEAK_HASH_DISPLACEMENT 7
-#define WEAK_COUNTER_MASK 3
-#define WEAK_COUNTER_MAX 2
-
#define TEMPORARY_STACK_SIZE 4096
#define STRING_BUFFER_SIZE 4096
#define DEFAULT_MUTATION_STACK_SIZE 1024
@@ -302,12 +296,6 @@ typedef struct lf_list_struct
char *module_name;
} LF_LIST;
-typedef struct weak_table_entry_struct
-{
- C_word item, /* item weakly held (symbol) */
- container; /* object holding reference to symbol, lowest 3 bits are */
-} WEAK_TABLE_ENTRY; /* also used as a counter, saturated at 2 or more */
-
typedef struct finalizer_node_struct
{
struct finalizer_node_struct
@@ -467,7 +455,6 @@ static C_TLS int
gc_count_1,
gc_count_1_total,
gc_count_2,
- weak_table_randomization,
stack_size_changed,
dlopen_flags,
heap_size_changed,
@@ -503,7 +490,6 @@ static C_TLS int
allocated_finalizer_count,
pending_finalizer_count,
callback_returned_flag;
-static C_TLS WEAK_TABLE_ENTRY *weak_item_table;
static C_TLS C_GC_ROOT *gc_root_list = NULL;
static C_TLS FINALIZER_NODE
*finalizer_list,
@@ -531,7 +517,6 @@ static void panic(C_char *msg) C_noret;
static void usual_panic(C_char *msg) C_noret;
static void horror(C_char *msg) C_noret;
static void C_fcall really_mark(C_word *x) C_regparm;
-static WEAK_TABLE_ENTRY *C_fcall lookup_weak_table_entry(C_word item, C_word container) C_regparm;
static C_cpsproc(values_continuation) C_noret;
static C_word add_symbol(C_word **ptr, C_word key, C_word string, C_SYMBOL_TABLE *stable);
static C_regparm int C_fcall C_in_new_heapp(C_word x);
@@ -563,6 +548,7 @@ static C_word basic_cmp(C_word x, C_word y, char *loc, int eqp);
static int bignum_cmp_unsigned(C_word x, C_word y);
static C_word C_fcall hash_string(int len, C_char *str, C_word m, C_word r, int ci) C_regparm;
static C_word C_fcall lookup(C_word key, int len, C_char *str, C_SYMBOL_TABLE *stable) C_regparm;
+static C_word C_fcall lookup_bucket(C_word sym, C_SYMBOL_TABLE *stable) C_regparm;
static double compute_symbol_table_load(double *avg_bucket_len, int *total);
static C_word C_fcall convert_string_to_number(C_char *str, int radix, C_word *fix, double *flo) C_regparm;
static C_regparm C_word str_to_bignum(C_word bignum, char *str, char *str_end, int radix);
@@ -573,6 +559,7 @@ static void C_fcall remark_system_globals(void) C_regparm;
static void C_fcall really_remark(C_word *x) C_regparm;
static C_word C_fcall intern0(C_char *name) C_regparm;
static void C_fcall update_locative_table(int mode) C_regparm;
+static void C_fcall update_symbol_tables(int mode) C_regparm;
static LF_LIST *find_module_handle(C_char *name);
static void set_profile_timer(C_uword freq);
static void take_profile_sample();
@@ -758,14 +745,6 @@ int CHICKEN_initialize(int heap, int stack, int symbols, void *toplevel)
C_gc_mutation_hook = NULL;
C_gc_trace_hook = NULL;
- /* Allocate weak item table: */
- if(C_enable_gcweak) {
- weak_item_table = (WEAK_TABLE_ENTRY *)C_calloc(WEAK_TABLE_SIZE, sizeof(WEAK_TABLE_ENTRY));
-
- if(weak_item_table == NULL)
- return 0;
- }
-
/* Initialize finalizer lists: */
finalizer_list = NULL;
finalizer_free_list = NULL;
@@ -2420,6 +2399,59 @@ C_regparm C_word C_fcall lookup(C_word key, int len, C_char *str, C_SYMBOL_TABLE
return C_SCHEME_FALSE;
}
+/* Mark a symbol as "persistent", to prevent it from being GC'ed */
+C_regparm C_word C_fcall C_i_persist_symbol(C_word sym)
+{
+ C_word bucket;
+
+ C_i_check_symbol(sym);
+
+ bucket = lookup_bucket(sym, NULL);
+ if (C_truep(bucket)) { /* It could be an uninterned symbol(?) */
+ /* Change weak to strong ref to ensure long-term survival */
+ C_block_header(bucket) = C_block_header(bucket) & ~C_SPECIALBLOCK_BIT;
+ /* Ensure survival on next minor GC */
+ if (C_in_stackp(sym)) C_mutate_slot(&C_block_item(bucket, 0), sym);
+ }
+ return C_SCHEME_UNDEFINED;
+}
+
+/* Possibly remove "persistence" of symbol, to allowed it to be GC'ed.
+ * This is only done if the symbol is unbound and has an empty plist.
+ */
+C_regparm C_word C_fcall C_i_unpersist_symbol(C_word sym)
+{
+ C_word bucket;
+
+ C_i_check_symbol(sym);
+
+ if (C_persistable_symbol(sym)) return C_SCHEME_FALSE;
+
+ bucket = lookup_bucket(sym, NULL);
+ if (C_truep(bucket)) { /* It could be an uninterned symbol(?) */
+ /* Turn it into a weak ref */
+ C_block_header(bucket) = C_block_header(bucket) | C_SPECIALBLOCK_BIT;
+ return C_SCHEME_TRUE;
+ }
+ return C_SCHEME_FALSE;
+}
+
+C_regparm C_word C_fcall lookup_bucket(C_word sym, C_SYMBOL_TABLE *stable)
+{
+ C_word bucket, str = C_block_item(sym, 1);
+ int key, len = C_header_size(str);
+
+ if (stable == NULL) stable = symbol_table;
+
+ key = hash_string(len, C_c_string(str), stable->size, stable->rand, 0);
+
+ for(bucket = stable->table[ key ]; bucket != C_SCHEME_END_OF_LIST;
+ bucket = C_block_item(bucket,1)) {
+ if (C_block_item(bucket,0) == sym) return bucket;
+ }
+ return C_SCHEME_FALSE;
+}
+
double compute_symbol_table_load(double *avg_bucket_len, int *total_n)
{
@@ -3242,18 +3274,16 @@ static void mark(C_word *x) { \
C_cblockend
#endif
-
C_regparm void C_fcall C_reclaim(void *trampoline, C_word c)
{
- int i, j, n, fcount, weakn = 0;
+ int i, j, n, fcount;
C_uword count, bytes;
- C_word *p, **msp, bucket, last, item, container;
+ C_word *p, **msp, bucket, last;
C_header h;
C_byte *tmp, *start;
LF_LIST *lfn;
C_SCHEME_BLOCK *bp;
C_GC_ROOT *gcrp;
- WEAK_TABLE_ENTRY *wep;
double tgc = 0;
C_SYMBOL_TABLE *stp;
volatile int finalizers_checked;
@@ -3282,9 +3312,6 @@ C_regparm void C_fcall C_reclaim(void *trampoline, C_word c)
gc_mode = GC_MINOR;
start = C_fromspace_top;
- if(C_enable_gcweak)
- weak_table_randomization = rand();
-
/* Entry point for second-level GC (on explicit request or because of full fromspace): */
#ifdef HAVE_SIGSETJMP
if(C_sigsetjmp(gc_restart, 0) || start >= C_fromspace_limit) {
@@ -3377,8 +3404,11 @@ C_regparm void C_fcall C_reclaim(void *trampoline, C_word c)
if(n > 0 && (h & C_BYTEBLOCK_BIT) == 0) {
if(h & C_SPECIALBLOCK_BIT) {
- --n;
- ++p;
+ /* Minor GC needs to be fast; always mark weakly held symbols */
+ if (gc_mode != GC_MINOR || h != C_WEAK_BUCKET_TAG) {
+ --n;
+ ++p;
+ }
}
while(n--) mark(p++);
@@ -3500,48 +3530,11 @@ C_regparm void C_fcall C_reclaim(void *trampoline, C_word c)
i_like_spaghetti:
++gc_count_2;
-
- if(C_enable_gcweak) {
- /* Check entries in weak item table and recover items ref'd only
- once, which are unbound symbols and have empty property-lists: */
- weakn = 0;
- wep = weak_item_table;
-
- for(i = 0; i < WEAK_TABLE_SIZE; ++i, ++wep)
- if(wep->item != 0) {
- if((wep->container & WEAK_COUNTER_MAX) == 0 && /* counter saturated? (more than 1) */
- is_fptr((item = C_block_header(wep->item)))) { /* and forwarded/collected */
- item = fptr_to_ptr(item); /* recover obj from forwarding ptr */
- container = wep->container & ~WEAK_COUNTER_MASK;
-
- if(C_header_bits(item) == C_SYMBOL_TYPE &&
- C_block_item(item, 0) == C_SCHEME_UNBOUND &&
- C_block_item(item, 2) == C_SCHEME_END_OF_LIST) {
- ++weakn;
- C_set_block_item(container, 0, C_SCHEME_UNDEFINED); /* clear reference to item */
- }
- }
-
- wep->item = wep->container = 0;
- }
-
- /* Remove empty buckets in symbol table: */
- for(stp = symbol_table_list; stp != NULL; stp = stp->next) {
- for(i = 0; i < stp->size; ++i) {
- last = 0;
-
- for(bucket = stp->table[ i ]; bucket != C_SCHEME_END_OF_LIST; bucket = C_block_item(bucket,1))
- if(C_block_item(bucket,0) == C_SCHEME_UNDEFINED) {
- if(last) C_set_block_item(last, 1, C_block_item(bucket,1));
- else stp->table[ i ] = C_block_item(bucket,1);
- }
- else last = bucket;
- }
- }
- }
}
if(gc_mode == GC_MAJOR) {
+ update_symbol_tables(gc_mode);
+
tgc = C_cpu_milliseconds() - tgc;
gc_ms += tgc;
timer_accumulated_gc_ms += tgc;
@@ -3577,9 +3570,6 @@ C_regparm void C_fcall C_reclaim(void *trampoline, C_word c)
(C_uword)tospace_start, (C_uword)tospace_top,
(C_uword)tospace_limit);
- if(gc_mode == GC_MAJOR && C_enable_gcweak && weakn)
- C_dbg("GC", C_text("%d recoverable weakly held items found\n"), weakn);
-
C_dbg("GC", C_text("%d locatives (from %d)\n"), locative_table_count, locative_table_size);
}
@@ -3622,11 +3612,10 @@ C_regparm void C_fcall mark_system_globals(void)
C_regparm void C_fcall really_mark(C_word *x)
{
- C_word val, item;
+ C_word val;
C_uword n, bytes;
C_header h;
C_SCHEME_BLOCK *p, *p2;
- WEAK_TABLE_ENTRY *wep;
val = *x;
@@ -3649,7 +3638,8 @@ C_regparm void C_fcall really_mark(C_word *x)
return;
}
- if((C_uword)val >= (C_uword)fromspace_start && (C_uword)val < (C_uword)C_fromspace_top) return;
+ if((C_uword)val >= (C_uword)fromspace_start && (C_uword)val < (C_uword)C_fromspace_top)
+ return;
p2 = (C_SCHEME_BLOCK *)C_align((C_uword)C_fromspace_top);
@@ -3679,25 +3669,9 @@ C_regparm void C_fcall really_mark(C_word *x)
C_memcpy(p2->data, p->data, bytes);
}
else { /* (major GC) */
- /* Increase counter (saturated at 2) if weakly held item (someone pointed to this object): */
- if(C_enable_gcweak &&
- (h & C_HEADER_TYPE_BITS) == C_SYMBOL_TYPE &&
- (wep = lookup_weak_table_entry(val, 0)) != NULL) {
- if((wep->container & WEAK_COUNTER_MAX) == 0) ++wep->container;
- }
-
if(is_fptr(h)) {
val = fptr_to_ptr(h);
- /* When we marked the bucket, it may have already referred to
- * the moved symbol instead of its original location. Re-check:
- */
- if(C_enable_gcweak &&
- (C_block_header(val) & C_HEADER_TYPE_BITS) == C_SYMBOL_TYPE &&
- (wep = lookup_weak_table_entry(*x, 0)) != NULL) {
- if((wep->container & WEAK_COUNTER_MAX) == 0) ++wep->container;
- }
-
if((C_uword)val >= (C_uword)tospace_start && (C_uword)val < (C_uword)tospace_top) {
*x = val;
return;
@@ -3711,15 +3685,6 @@ C_regparm void C_fcall really_mark(C_word *x)
/* Link points into fromspace and into a link which points into from- or tospace: */
val = fptr_to_ptr(h);
- /* See above: might happen twice */
- if(C_enable_gcweak &&
- (C_block_header(val) & C_HEADER_TYPE_BITS) == C_SYMBOL_TYPE &&
- /* Check both the original and intermediate location: */
- ((wep = lookup_weak_table_entry((C_word)p, 0)) != NULL ||
- (wep = lookup_weak_table_entry(*x, 0)) != NULL)) {
- if((wep->container & WEAK_COUNTER_MAX) == 0) ++wep->container;
- }
-
if((C_uword)val >= (C_uword)tospace_start && (C_uword)val < (C_uword)tospace_top) {
*x = val;
return;
@@ -3739,16 +3704,6 @@ C_regparm void C_fcall really_mark(C_word *x)
}
#endif
- if(C_enable_gcweak && (h & C_HEADER_TYPE_BITS) == C_BUCKET_TYPE) {
- item = C_block_item(val,0);
-
- /* Lookup item in weak item table or add entry: */
- if((wep = lookup_weak_table_entry(item, (C_word)p2)) != NULL) {
- /* If item is already forwarded, then set count to 2: */
- if(is_fptr(C_block_header(item))) wep->container |= 2;
- }
- }
-
n = C_header_size(p);
bytes = (h & C_BYTEBLOCK_BIT) ? n : n * sizeof(C_word);
@@ -3788,19 +3743,17 @@ static void remark(C_word *x) { \
C_cblockend
#endif
-
/* Do a major GC into a freshly allocated heap: */
C_regparm void C_fcall C_rereclaim2(C_uword size, int relative_resize)
{
int i, j;
C_uword count, n, bytes;
- C_word *p, **msp, item, last;
+ C_word *p, **msp, bucket, last;
C_header h;
C_byte *tmp, *start;
LF_LIST *lfn;
C_SCHEME_BLOCK *bp;
- WEAK_TABLE_ENTRY *wep;
C_GC_ROOT *gcrp;
C_SYMBOL_TABLE *stp;
FINALIZER_NODE *flist;
@@ -3913,14 +3866,6 @@ C_regparm void C_fcall C_rereclaim2(C_uword size, int relative_resize)
remark(&flist->finalizer);
}
- /* Clear weakly held items: */
- if(C_enable_gcweak) {
- wep = weak_item_table;
-
- for(i = 0; i < WEAK_TABLE_SIZE; ++i, ++wep)
- wep->item = wep->container = 0;
- }
-
/* Mark trace-buffer: */
for(tinfo = trace_buffer; tinfo < trace_buffer_limit; ++tinfo) {
remark(&tinfo->cooked1);
@@ -3955,6 +3900,8 @@ C_regparm void C_fcall C_rereclaim2(C_uword size, int relative_resize)
heap_scan_top = (C_byte *)bp + C_align(bytes) + sizeof(C_word);
}
+ update_symbol_tables(GC_REALLOC);
+
heap_free (heapspace1, heapspace1_size);
heap_free (heapspace2, heapspace2_size);
@@ -4004,7 +3951,6 @@ C_regparm void C_fcall really_remark(C_word *x)
C_uword n, bytes;
C_header h;
C_SCHEME_BLOCK *p, *p2;
- WEAK_TABLE_ENTRY *wep;
val = *x;
@@ -4179,34 +4125,66 @@ C_regparm void C_fcall update_locative_table(int mode)
if(mode != GC_REALLOC) locative_table_count = hi;
}
-
-C_regparm WEAK_TABLE_ENTRY *C_fcall lookup_weak_table_entry(C_word item, C_word container)
+C_regparm void C_fcall update_symbol_tables(int mode)
{
- C_uword
- key = (C_uword)item >> 2,
- disp = 0,
- n;
- WEAK_TABLE_ENTRY *wep;
+ int weakn = 0, i;
+ C_word bucket, last, sym, h;
+ C_SYMBOL_TABLE *stp;
- for(n = 0; n < WEAK_HASH_ITERATIONS; ++n) {
- key = (key + disp + weak_table_randomization) % WEAK_TABLE_SIZE;
- wep = &weak_item_table[ key ];
+ assert(mode != GC_MINOR); /* Call only in major or realloc mode */
+ if(C_enable_gcweak) {
+ /* Update symbol locations through fptrs or drop if unreferenced */
+ for(stp = symbol_table_list; stp != NULL; stp = stp->next) {
+ for(i = 0; i < stp->size; ++i) {
+ last = 0;
- if(wep->item == 0) {
- if(container != 0) {
- /* Add fresh entry: */
- wep->item = item;
- wep->container = container;
- return wep;
- }
+ for(bucket = stp->table[ i ]; bucket != C_SCHEME_END_OF_LIST; bucket = C_block_item(bucket,1)) {
+
+ sym = C_block_item(bucket, 0);
+ h = C_block_header(sym);
- return NULL;
+ /* Resolve any forwarding pointers */
+ while(is_fptr(h)) {
+ sym = fptr_to_ptr(h);
+ h = C_block_header(sym);
+ }
+
+ assert((h & C_HEADER_TYPE_BITS) == C_SYMBOL_TYPE);
+
+ /* If the symbol is unreferenced, drop it: */
+ if(!C_truep(C_permanentp(sym)) && (mode == GC_REALLOC ?
+ !C_in_new_heapp(sym) :
+ !C_in_fromspacep(sym))) {
+
+ if(last) C_set_block_item(last, 1, C_block_item(bucket,1));
+ else stp->table[ i ] = C_block_item(bucket,1);
+
+ assert(!C_persistable_symbol(sym));
+ ++weakn;
+ } else {
+ C_set_block_item(bucket,0,sym); /* Might have moved */
+ last = bucket;
+ }
+ }
+ }
}
- else if(wep->item == item) return wep;
- else disp += WEAK_HASH_DISPLACEMENT;
+ if(gc_report_flag && weakn)
+ C_dbg("GC", C_text("%d recoverable weakly held items found\n"), weakn);
+ } else {
+#ifdef DEBUGBUILD
+ /* Sanity check: all symbols should've been marked */
+ for(stp = symbol_table_list; stp != NULL; stp = stp->next)
+ for(i = 0; i < stp->size; ++i)
+ for(bucket = stp->table[ i ]; bucket != C_SCHEME_END_OF_LIST; bucket = C_block_item(bucket,1)) {
+ sym = C_block_item(bucket, 0);
+ assert(!is_fptr(C_block_header(sym)) &&
+ (C_truep(C_permanentp(sym)) ||
+ (mode == GC_REALLOC ?
+ C_in_new_heapp(sym) :
+ C_in_fromspacep(sym))));
+ }
+#endif
}
-
- return NULL;
}
@@ -13193,7 +13171,10 @@ C_i_getprop(C_word sym, C_word prop, C_word def)
C_regparm C_word C_fcall
C_putprop(C_word **ptr, C_word sym, C_word prop, C_word val)
{
- C_word pl = C_block_item(sym, 2);
+ C_word pl = C_symbol_plist(sym);
+
+ /* Newly added plist? Ensure the symbol stays! */
+ if (pl == C_SCHEME_END_OF_LIST) C_i_persist_symbol(sym);
while(pl != C_SCHEME_END_OF_LIST) {
if(C_block_item(pl, 0) == prop) {
@@ -13203,9 +13184,9 @@ C_putprop(C_word **ptr, C_word sym, C_word prop, C_word val)
else pl = C_u_i_cdr(C_u_i_cdr(pl));
}
- pl = C_a_pair(ptr, val, C_block_item(sym, 2));
+ pl = C_a_pair(ptr, val, C_symbol_plist(sym));
pl = C_a_pair(ptr, prop, pl);
- C_mutate_slot(&C_block_item(sym, 2), pl);
+ C_mutate_slot(&C_symbol_plist(sym), pl);
return val;
}
diff --git a/tests/runtests.bat b/tests/runtests.bat
index 8e488d0..00f7687 100644
--- a/tests/runtests.bat
+++ b/tests/runtests.bat
@@ -481,8 +481,7 @@ echo ======================================== symbol-GC tests ...
%compile% symbolgc-tests.scm
if errorlevel 1 exit /b 1
a.out -:w
-rem Currently disabled, because this may leave 1 symbol unreclaimed.
-rem if errorlevel 1 exit /b 1
+if errorlevel 1 exit /b 1
echo ======================================== finalizer tests ...
%interpret% -s test-finalizers.scm
diff --git a/tests/runtests.sh b/tests/runtests.sh
index 279f70f..13f4405 100755
--- a/tests/runtests.sh
+++ b/tests/runtests.sh
@@ -415,8 +415,7 @@ done
echo "======================================== symbol-GC tests ..."
$compile symbolgc-tests.scm
-# Currently disabled, because this may leave 1 symbol unreclaimed.
-./a.out -:w || echo "*** FAILED ***"
+./a.out -:w
echo "======================================== finalizer tests ..."
$interpret -s test-finalizers.scm
diff --git a/tests/symbolgc-tests.scm b/tests/symbolgc-tests.scm
index 30b32a4..0b45859 100644
--- a/tests/symbolgc-tests.scm
+++ b/tests/symbolgc-tests.scm
@@ -2,18 +2,23 @@
;
; - run this with the "-:w" option
-(use gc)
+(use gc (chicken format))
(assert (##sys#fudge 15) "please run this test with the `-:w' runtime option")
-(define (gcsome #!optional (n 100))
- (do ((i n (sub1 i))) ((zero? i)) (gc #t)))
+;; Ensure counts are defined before creating the disposable symbols.
+;; This way, this program can also be run in interpreted mode.
+(define *count-before* #f)
+(define *count-after* #f)
-(gcsome)
+;; Force major GC to ensure there are no collectible symbols left
+;; before we start, otherwise the GC might clean these up and we'd end
+;; up with less symbols than we started with!
+(gc #t)
-(define *count1* (vector-ref (##sys#symbol-table-info) 2))
+(set! *count-before* (vector-ref (##sys#symbol-table-info) 2))
-(print "starting with " *count1* " symbols")
+(print "starting with " *count-before* " symbols")
(print "interning 10000 symbols ...")
@@ -23,17 +28,15 @@
(print "recovering ...")
-(let loop ((i 0))
- (let ((n (vector-ref (##sys#symbol-table-info) 2)))
- (print* (- n *count1*) " ")
- (cond ((> i 100)
- (unless (<= n *count1*)
- (error "unable to reclaim all symbols")))
- ((< (- n *count1*) 100) ; allow some
- (gc #t)
- (loop (+ i 1)))
- (else
- (gc #t)
- (loop 0)))))
+;; Force major GC, which should reclaim every last symbol we just
+;; created, as well as "i", the loop counter.
+(gc #t)
+
+;; Don't use LET, which would introduce a fresh identifier, which is a
+;; new symbol (at least, in interpreted mode)
+(set! *count-after* (vector-ref (##sys#symbol-table-info) 2))
+(print* (- *count-after* *count-before*) " newly interned symbols left")
+(unless (= *count-after* *count-before*)
+ (error "unable to reclaim all symbols"))
(print "\ndone.")
--
2.1.4
From 9c9c29cfd07b3d1e0d858dcd8d118f1f685126f6 Mon Sep 17 00:00:00 2001
From: Peter Bex <pe...@more-magic.net>
Date: Sat, 3 Sep 2016 18:32:37 +0200
Subject: [PATCH 2/3] Make weak symbol GC the default.
Because symbol GC is now nothing special, we can do this. The overhead
of the symbol table fixup in update_symbol_tables() is neglible, and in
many cases offset by the gains of not needlessly copying symbol data.
This removes the -:w option, and the SYMBOLGC compile-time option no
longer does anything.
---
Makefile.aix | 3 --
Makefile.android | 3 --
Makefile.bsd | 3 --
Makefile.cross-linux-mingw | 3 --
Makefile.cygwin | 3 --
Makefile.haiku | 3 --
Makefile.hurd | 3 --
Makefile.ios | 3 --
Makefile.linux | 3 --
Makefile.macosx | 3 --
Makefile.mingw | 3 --
Makefile.mingw-msys | 3 --
Makefile.solaris | 3 --
NEWS | 1 +
README | 9 ------
chicken.h | 6 ++--
config.make | 3 --
runtime.c | 79 ++++++++++++++++------------------------------
tests/runtests.bat | 2 +-
tests/runtests.sh | 2 +-
tests/symbolgc-tests.scm | 4 ---
21 files changed, 32 insertions(+), 113 deletions(-)
diff --git a/Makefile.aix b/Makefile.aix
index 3884dce..977e3b2 100644
--- a/Makefile.aix
+++ b/Makefile.aix
@@ -97,9 +97,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/Makefile.android b/Makefile.android
index c48b4f7..fb1edeb 100644
--- a/Makefile.android
+++ b/Makefile.android
@@ -91,9 +91,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/Makefile.bsd b/Makefile.bsd
index bf64a15..ceb0b72 100644
--- a/Makefile.bsd
+++ b/Makefile.bsd
@@ -97,9 +97,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/Makefile.cross-linux-mingw b/Makefile.cross-linux-mingw
index 6bb28be..721bea4 100644
--- a/Makefile.cross-linux-mingw
+++ b/Makefile.cross-linux-mingw
@@ -114,9 +114,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)rules.make
diff --git a/Makefile.cygwin b/Makefile.cygwin
index b4587f5..94bb814 100644
--- a/Makefile.cygwin
+++ b/Makefile.cygwin
@@ -111,9 +111,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/Makefile.haiku b/Makefile.haiku
index 11787e0..94466b4 100644
--- a/Makefile.haiku
+++ b/Makefile.haiku
@@ -91,9 +91,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/Makefile.hurd b/Makefile.hurd
index 1feb580..3d11c77 100644
--- a/Makefile.hurd
+++ b/Makefile.hurd
@@ -92,9 +92,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/Makefile.ios b/Makefile.ios
index 70a5f27..9f46064 100644
--- a/Makefile.ios
+++ b/Makefile.ios
@@ -95,9 +95,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/Makefile.linux b/Makefile.linux
index 276f9ff..2917d0d 100644
--- a/Makefile.linux
+++ b/Makefile.linux
@@ -99,9 +99,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/Makefile.macosx b/Makefile.macosx
index 13792bd..949428a 100644
--- a/Makefile.macosx
+++ b/Makefile.macosx
@@ -120,9 +120,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/Makefile.mingw b/Makefile.mingw
index f9cda73..b791f99 100644
--- a/Makefile.mingw
+++ b/Makefile.mingw
@@ -101,9 +101,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo #define C_GC_HOOKS >>$@
endif
-ifdef SYMBOLGC
- echo #define C_COLLECT_ALL_SYMBOLS >>$@
-endif
type chicken-defaults.h >>$@
include $(SRCDIR)rules.make
diff --git a/Makefile.mingw-msys b/Makefile.mingw-msys
index 981b8d5..207f2bd 100644
--- a/Makefile.mingw-msys
+++ b/Makefile.mingw-msys
@@ -106,9 +106,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/Makefile.solaris b/Makefile.solaris
index c290665..0efd46f 100644
--- a/Makefile.solaris
+++ b/Makefile.solaris
@@ -121,9 +121,6 @@ chicken-config.h: chicken-defaults.h
ifdef GCHOOKS
echo "#define C_GC_HOOKS" >>$@
endif
-ifdef SYMBOLGC
- echo "#define C_COLLECT_ALL_SYMBOLS" >>$@
-endif
cat chicken-defaults.h >>$@
include $(SRCDIR)/rules.make
diff --git a/NEWS b/NEWS
index 34ec4bc..7587d59 100644
--- a/NEWS
+++ b/NEWS
@@ -10,6 +10,7 @@
flag to a bitmap, to allow for multidirectional ports.
- Weak symbol GC is faster, simpler, and can now collect all
unreferenced symbols instead of a maximum of 997 per major GC.
+ - The -:w option has been removed; symbols are now always collected.
- Compiler
- Fixed an off by one allocation problem in generated C code for (list ...).
diff --git a/README b/README
index eaf9f93..4dcaa0e 100644
--- a/README
+++ b/README
@@ -164,15 +164,6 @@
`chicken-status' will not be generated, as it is mostly
useless unless compiled code can be loaded.
- SYMBOLGC=1
- Always enable garbage collection for unused symbols in the
- symbol table by default. This will result in slightly slower
- garbage collection, but minimizes the amount of garbage
- retained at runtime (which might be important for long
- running server applications). If you don't specify this
- option you can still enable symbol GC at runtime by passing
- the `-:w' runtime option when running the program.
-
EXTRA_CHICKEN_OPTIONS=...
Additional options that should be passed to `chicken' when
building the system.
diff --git a/chicken.h b/chicken.h
index 2cd705b..a94de73 100644
--- a/chicken.h
+++ b/chicken.h
@@ -1765,7 +1765,6 @@ C_varextern C_TLS int
C_abort_on_thread_exceptions,
C_interrupts_enabled,
C_disable_overflow_check,
- C_enable_gcweak,
C_heap_size_is_fixed,
C_max_pending_finalizers,
C_trace_buffer_size,
@@ -2781,8 +2780,7 @@ C_inline int C_persistable_symbol(C_word x)
{
C_word val = C_symbol_value(x);
/* Symbol is bound (and not a keyword), or has a non-empty plist */
- return (!C_enable_gcweak || /* Overrides to always true */
- (val != C_SCHEME_UNBOUND && val != x) ||
+ return ((val != C_SCHEME_UNBOUND && val != x) ||
C_symbol_plist(x) != C_SCHEME_END_OF_LIST);
}
@@ -3422,7 +3420,7 @@ C_inline C_word C_fcall C_a_bucket(C_word **ptr, C_word head, C_word tail)
{
C_word *p = *ptr, *p0 = p;
- *(p++) = C_enable_gcweak ? C_WEAK_BUCKET_TAG : C_BUCKET_TAG;
+ *(p++) = C_WEAK_BUCKET_TAG; /* Changes to strong if sym is persisted */
*(p++) = head;
*(p++) = tail;
*ptr = p;
diff --git a/config.make b/config.make
index 04d7cf1..0cfe765 100644
--- a/config.make
+++ b/config.make
@@ -20,9 +20,6 @@
# Build static runtime library only:
#STATICBUILD=1
-# Enable GC of symbols:
-#SYMBOLGC=1
-
# Use alternative C compiler
#C_COMPILER=
diff --git a/runtime.c b/runtime.c
index 14732bf..f2662d2 100644
--- a/runtime.c
+++ b/runtime.c
@@ -370,11 +370,6 @@ C_TLS int
C_enable_repl,
C_interrupts_enabled,
C_disable_overflow_check,
-#ifdef C_COLLECT_ALL_SYMBOLS
- C_enable_gcweak = 1,
-#else
- C_enable_gcweak = 0,
-#endif
C_heap_size_is_fixed,
C_trace_buffer_size = DEFAULT_TRACE_BUFFER_SIZE,
C_max_pending_finalizers = C_DEFAULT_MAX_PENDING_FINALIZERS,
@@ -1459,10 +1454,6 @@ void CHICKEN_parse_command_line(int argc, char *argv[], C_word *heap, C_word *st
gc_report_flag = 2;
break;
- case 'w':
- C_enable_gcweak = 1;
- break;
-
case 'P':
profiling = 1;
profile_frequency = arg_val(ptr);
@@ -4132,59 +4123,43 @@ C_regparm void C_fcall update_symbol_tables(int mode)
C_SYMBOL_TABLE *stp;
assert(mode != GC_MINOR); /* Call only in major or realloc mode */
- if(C_enable_gcweak) {
- /* Update symbol locations through fptrs or drop if unreferenced */
- for(stp = symbol_table_list; stp != NULL; stp = stp->next) {
- for(i = 0; i < stp->size; ++i) {
- last = 0;
+ /* Update symbol locations through fptrs or drop if unreferenced */
+ for(stp = symbol_table_list; stp != NULL; stp = stp->next) {
+ for(i = 0; i < stp->size; ++i) {
+ last = 0;
- for(bucket = stp->table[ i ]; bucket != C_SCHEME_END_OF_LIST; bucket = C_block_item(bucket,1)) {
+ for(bucket = stp->table[ i ]; bucket != C_SCHEME_END_OF_LIST; bucket = C_block_item(bucket,1)) {
- sym = C_block_item(bucket, 0);
- h = C_block_header(sym);
+ sym = C_block_item(bucket, 0);
+ h = C_block_header(sym);
- /* Resolve any forwarding pointers */
- while(is_fptr(h)) {
- sym = fptr_to_ptr(h);
- h = C_block_header(sym);
- }
+ /* Resolve any forwarding pointers */
+ while(is_fptr(h)) {
+ sym = fptr_to_ptr(h);
+ h = C_block_header(sym);
+ }
- assert((h & C_HEADER_TYPE_BITS) == C_SYMBOL_TYPE);
+ assert((h & C_HEADER_TYPE_BITS) == C_SYMBOL_TYPE);
- /* If the symbol is unreferenced, drop it: */
- if(!C_truep(C_permanentp(sym)) && (mode == GC_REALLOC ?
- !C_in_new_heapp(sym) :
- !C_in_fromspacep(sym))) {
+ /* If the symbol is unreferenced, drop it: */
+ if(!C_truep(C_permanentp(sym)) && (mode == GC_REALLOC ?
+ !C_in_new_heapp(sym) :
+ !C_in_fromspacep(sym))) {
- if(last) C_set_block_item(last, 1, C_block_item(bucket,1));
- else stp->table[ i ] = C_block_item(bucket,1);
+ if(last) C_set_block_item(last, 1, C_block_item(bucket,1));
+ else stp->table[ i ] = C_block_item(bucket,1);
- assert(!C_persistable_symbol(sym));
- ++weakn;
- } else {
- C_set_block_item(bucket,0,sym); /* Might have moved */
- last = bucket;
- }
+ assert(!C_persistable_symbol(sym));
+ ++weakn;
+ } else {
+ C_set_block_item(bucket,0,sym); /* Might have moved */
+ last = bucket;
}
}
}
- if(gc_report_flag && weakn)
- C_dbg("GC", C_text("%d recoverable weakly held items found\n"), weakn);
- } else {
-#ifdef DEBUGBUILD
- /* Sanity check: all symbols should've been marked */
- for(stp = symbol_table_list; stp != NULL; stp = stp->next)
- for(i = 0; i < stp->size; ++i)
- for(bucket = stp->table[ i ]; bucket != C_SCHEME_END_OF_LIST; bucket = C_block_item(bucket,1)) {
- sym = C_block_item(bucket, 0);
- assert(!is_fptr(C_block_header(sym)) &&
- (C_truep(C_permanentp(sym)) ||
- (mode == GC_REALLOC ?
- C_in_new_heapp(sym) :
- C_in_fromspacep(sym))));
- }
-#endif
}
+ if(gc_report_flag && weakn)
+ C_dbg("GC", C_text("%d recoverable weakly held items found\n"), weakn);
}
@@ -4901,7 +4876,7 @@ C_regparm C_word C_fcall C_fudge(C_word fudge_factor)
return C_mk_bool(C_interrupts_enabled);
case C_fix(15): /* symbol-gc enabled? */
- return C_mk_bool(C_enable_gcweak);
+ return C_SCHEME_TRUE;
case C_fix(16): /* milliseconds (wall clock) */
panic(C_text("(##sys#fudge 16) [current wall clock milliseconds] not implemented"));
diff --git a/tests/runtests.bat b/tests/runtests.bat
index 00f7687..a05f206 100644
--- a/tests/runtests.bat
+++ b/tests/runtests.bat
@@ -480,7 +480,7 @@ for %%s in (100000 120000 200000 250000 300000 350000 400000 450000 500000) do (
echo ======================================== symbol-GC tests ...
%compile% symbolgc-tests.scm
if errorlevel 1 exit /b 1
-a.out -:w
+a.out
if errorlevel 1 exit /b 1
echo ======================================== finalizer tests ...
diff --git a/tests/runtests.sh b/tests/runtests.sh
index 13f4405..4f447ee 100755
--- a/tests/runtests.sh
+++ b/tests/runtests.sh
@@ -415,7 +415,7 @@ done
echo "======================================== symbol-GC tests ..."
$compile symbolgc-tests.scm
-./a.out -:w
+./a.out
echo "======================================== finalizer tests ..."
$interpret -s test-finalizers.scm
diff --git a/tests/symbolgc-tests.scm b/tests/symbolgc-tests.scm
index 0b45859..923ee71 100644
--- a/tests/symbolgc-tests.scm
+++ b/tests/symbolgc-tests.scm
@@ -1,11 +1,7 @@
;;;; symbolgc-tests.scm
-;
-; - run this with the "-:w" option
(use gc (chicken format))
-(assert (##sys#fudge 15) "please run this test with the `-:w' runtime option")
-
;; Ensure counts are defined before creating the disposable symbols.
;; This way, this program can also be run in interpreted mode.
(define *count-before* #f)
--
2.1.4
+---[1]: |-> installation-prefix: /home/sjamaan/chickens/chicken-5-original |-> csc-options: |-> repetitions: 10 +---[2]: |-> installation-prefix: /home/sjamaan/chickens/chicken-5-original-gcweak |-> csc-options: |-> repetitions: 10 +---[3]: |-> installation-prefix: /home/sjamaan/chickens/chicken-5-with-patches |-> csc-options: |-> repetitions: 10 Displaying normalized results (larger numbers indicate better results) === === cpu-time === Programs [1] [2] [3] ================================================== 0_________________________1.00______1.00______1.00 binarytrees_______________1.00______1.05______1.18 boyer_____________________1.18______1.00______1.12 browse____________________1.10______1.02______1.00 conform___________________1.03______1.04______1.00 cpstak____________________1.00______1.03______1.00 ctak______________________1.00______1.06______1.11 dderiv____________________1.00______1.07______1.11 deriv_____________________1.18______1.00______1.11 destructive_______________1.00______1.00______1.05 dfa_______________________1.00______1.02______1.04 div-iter__________________1.13______1.00______1.13 div-rec___________________1.00______1.02______1.02 dynamic___________________1.14______1.00______1.15 earley____________________1.29______1.00______1.22 fannkuch__________________1.05______1.06______1.00 fft_______________________1.15______1.00______1.13 fib_______________________1.08______1.08______1.00 fibc______________________1.00______1.00______1.01 fibfp_____________________1.00______1.08______1.05 fprint____________________1.19______1.00______1.14 fread_____________________1.06______1.00______1.04 gcbench___________________1.03______1.00______1.04 gold______________________1.01______1.00______1.00 gold2_____________________1.01______1.00______1.00 graphs____________________1.00______1.01______1.03 hanoi_____________________1.00______1.03______1.05 integ_____________________1.00______1.00______1.03 integ2____________________1.02______1.00______1.00 kanren____________________1.08______1.00______1.08 kernwyk-ackermann_________1.24______1.00______1.25 kernwyk-array_____________1.01______1.00______1.05 kernwyk-cat_______________1.04______1.00______1.02 kernwyk-string____________1.04______1.00______1.03 kernwyk-sum_______________1.01______1.00______1.04 kernwyk-tail______________1.00______1.09______1.14 kernwyk-wc________________1.01______1.00______1.00 knucleotide_______________1.10______1.00______1.42 lattice___________________1.05______1.00______1.06 matrix____________________1.02______1.00______1.05 maze______________________1.04______1.00______1.05 mazefun___________________1.02______1.00______1.07 mbrot_____________________1.08______1.23______1.00 nbody_____________________1.01______1.00______1.02 nboyer____________________1.03______1.00______1.09 nestedloop________________1.04______1.03______1.00 nfa_______________________1.00______1.00______1.00 nqueens___________________1.08______1.00______1.00 ntakl_____________________1.15______1.00______1.10 nucleic2__________________1.01______1.00______1.00 paraffins_________________1.17______1.00______1.21 parsing___________________1.00______1.00______1.02 pnpoly____________________1.00______1.01______1.05 primes____________________1.00______1.01______1.03 psyntax___________________1.03______1.00______1.04 puzzle____________________1.00______1.13______1.11 ray_______________________1.01______1.00______1.04 ray2______________________1.02______1.00______1.00 sboyer____________________1.01______1.00______1.00 scheme____________________1.23______1.07______1.00 sieves-eratosthenes_______1.22______1.00______1.25 simplex___________________1.06______1.00______1.09 slatex____________________1.00______1.01______1.05 sort1_____________________1.00______1.01______1.02 tak_______________________1.01______1.00______1.00 takl______________________1.00______1.00______1.04 takr______________________1.00______1.01______1.02 traverse__________________1.06______1.00______1.08 travinit__________________1.00______1.08______1.22 triangl___________________1.00______1.10______1.33
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