Raymond Toy pushed to branch issue-243-weak-pointer-to-static-array at cmucl / cmucl

Commits: 5472c92c by Raymond Toy at 2024-02-16T16:05:27-08:00 Don't add to the *before-gc-hooks* to clear static vector marks.

- - - - - 060bbae4 by Raymond Toy at 2024-02-17T08:43:19-08:00 Clean up implementation

Add `#defines` for the various bits needed to handle processing of static arrays.

When scavenging weak pointers to static arrays, clear out the visited bit, just to be safe.

Clean up debugging prints.

Add phase 4 to go through all the remaining static vectors and unmark them so we don't have to do that in Lisp.

- - - - - 255af7a5 by Raymond Toy at 2024-02-17T09:03:01-08:00 Clean up prints some more

- - - - -

2 changed files:

- src/code/array.lisp - src/lisp/gencgc.c

Changes:

===================================== src/code/array.lisp ===================================== @@ -406,6 +406,7 @@ (delete-if-not #'weak-pointer-value *static-vectors*))))

;; Clear the mark bit of all of static vectors before GC +#+nil (pushnew 'clear-static-vector-mark *before-gc-hooks*) ;; Clean up any unreferenced static vectors after GC has run. (pushnew 'finalize-static-vectors *after-gc-hooks*)

===================================== src/lisp/gencgc.c ===================================== @@ -32,6 +32,25 @@ */ #define EQ_BASED_HASH_VALUE 0x80000000

+/* + * If the header value for a vector has this bit set, then it is a + * static vector. + */ +#define STATIC_VECTOR_HEADER_BIT 0x1 + +/* + * Mark bit for static vectors. If set in the header, the static + * vector is in use. + */ +#define STATIC_VECTOR_MARK_BIT 0x80000000 + +/* + * Visited bit for static vectors. When scanning weak pointers for + * static vectors, this bit indicates that we've visited this static + * vector already. + */ +#define STATIC_VECTOR_VISITED_BIT 0x08000000 + #define gc_abort() lose("GC invariant lost! File "%s", line %d\n", \ __FILE__, __LINE__)

@@ -241,7 +260,7 @@ unsigned counters_verbose = 0; * If true, then some debugging information is printed when scavenging * static (malloc'ed) arrays. */ -boolean debug_static_array_p = 0; +boolean debug_static_array_p = 1;

/* * To enable the use of page protection to help avoid the scavenging @@ -2718,13 +2737,14 @@ scav_static_vector(lispobj object) ptr, (unsigned long) header); }

- static_p = (HeaderValue(header) & 1) == 1; + static_p = (HeaderValue(header) & STATIC_VECTOR_HEADER_BIT) == 1; if (static_p) { /* - * We have a static vector. Mark it as - * reachable by setting the MSB of the header. + * We have a static vector. Mark it as reachable by + * setting the MSB of the header. And clear out any + * possible visited bit. */ - *ptr = header | 0x80000000; + *ptr = (header | STATIC_VECTOR_MARK_BIT) & ~STATIC_VECTOR_VISITED_BIT; if (debug_static_array_p) { fprintf(stderr, "Scavenged static vector @%p, header = 0x%lx\n", ptr, (unsigned long) header); @@ -5402,10 +5422,9 @@ scan_static_vectors(void) { struct weak_pointer *wp; struct weak_pointer *static_vector_list = NULL; - const int scan_mark_flag = 0x8000;

if (debug_static_array_p) { - printf("Phase 1: find static vectors\n"); + printf("Phase 1: Find static vectors\n"); }

/* @@ -5428,15 +5447,16 @@ scan_static_vectors(void) if (maybe_static_array_p(*header)) {

if (debug_static_array_p) { - printf("Adding %p header = 0x%08lx, next = %p\n", - wp, *header, wp->next); + printf(" Add: wp %p value %p header 0x%08lx, next = %p\n", + wp, (lispobj *) wp->value, *header, wp->next); }

wp->next = static_vector_list; static_vector_list = wp; } else { if (debug_static_array_p) { - printf("Skipping %p header = 0x%08lx\n", wp, *header); + printf(" Skip: wp %p value %p header 0x%08lx\n", + wp, (lispobj *) wp->value, *header); } } } @@ -5444,7 +5464,7 @@ scan_static_vectors(void) }

if (debug_static_array_p) { - printf("Phase 2\n"); + printf("Phase 2: Visit unused static vectors\n"); }

/* @@ -5458,25 +5478,26 @@ scan_static_vectors(void) lispobj *header = (lispobj *) PTR(wp->value);

if (debug_static_array_p) { - printf("wp %p value 0x%08lx header 0x%08lx\n", - wp, wp->value, *header); + printf(" wp %p value %p header 0x%08lx\n", + wp, (lispobj *) wp->value, *header); }

/* * If the static vector is unused (mark bit clear) and if we - * haven't seen this vector before, set the scan flag. + * haven't seen this vector before, set the visited flag. If + * we have visited this vector before, break the weak pointer. */ - if ((*header & 0x80000000) == 0) { + if ((*header & STATIC_VECTOR_MARK_BIT) == 0) { /* Unused static vector */ - if ((*header & scan_mark_flag) == 0) { + if ((*header & STATIC_VECTOR_VISITED_BIT) == 0) { if (debug_static_array_p) { - printf(" Mark vector\n"); + printf(" Mark vector\n"); }

- *header |= scan_mark_flag; + *header |= STATIC_VECTOR_VISITED_BIT; } else { if (debug_static_array_p) { - printf(" Break weak pointer %p\n", wp); + printf(" Break weak pointer %p\n", wp); }

wp->value = NIL; @@ -5499,16 +5520,19 @@ scan_static_vectors(void) for (wp = static_vector_list; wp; wp = wp->next) { lispobj *header = (lispobj *) PTR(wp->value);

- printf("wp = %p, header = 0x%08lx\n", wp, *header); + if (debug_static_array_p) { + printf(" wp %p value %p header 0x%08lx\n", + wp, (lispobj*) wp->value, *header); + }

/* * Only free the arrays where the mark bit is clear. */ if (wp->broken == NIL) { - if ((*header & 0x80000000) == 0) { + if ((*header & STATIC_VECTOR_MARK_BIT) == 0) { lispobj *static_array = (lispobj *) PTR(wp->value); if (debug_static_array_p) { - printf("free wp %p: %p\n", wp, static_array); + printf(" Free wp\n"); }

wp->value = NIL; @@ -5518,6 +5542,27 @@ scan_static_vectors(void) } } } + + if (debug_static_array_p) { + printf("Phase 4: unmark static vectors\n"); + } + + for (wp = static_vector_list; wp; wp = wp->next) { + lispobj *header = (lispobj *) PTR(wp->value); + + if (debug_static_array_p) { + printf(" wp %p value %p broken %d header 0x%08lx\n", + wp, (lispobj*) wp->value, wp->broken == T, *header); + } + + if ((*header & STATIC_VECTOR_MARK_BIT) != 0) { + if (debug_static_array_p) { + printf(" Clearing mark bit\n"); + } + + *header &= ~STATIC_VECTOR_MARK_BIT; + } + } }

void

View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/compare/959be526befaead7b46d43b...