uCBQN/src/opt/gc.c

186 lines
4.4 KiB
C

#include "gc.h"
#if ENABLE_GC
static void mm_freeFreedAndMerge(void);
#endif
#ifdef LOG_GC
#include "../utils/time.h"
#endif
u64 gc_depth = 1;
vfn gc_roots[8];
u32 gc_rootSz;
void gc_addFn(vfn f) {
if (gc_rootSz>=8) err("Too many GC root functions");
gc_roots[gc_rootSz++] = f;
}
Value* gc_rootObjs[512];
u32 gc_rootObjSz;
void gc_add(B x) {
assert(isVal(x));
if (gc_rootObjSz>=512) err("Too many GC root objects");
gc_rootObjs[gc_rootObjSz++] = v(x);
}
B* gc_rootBRefs[64]; u32 gc_rootBRefsSz;
void gc_add_ref(B* x) {
if (gc_rootBRefsSz>=64) err("Too many GC root B refs");
gc_rootBRefs[gc_rootBRefsSz++] = x;
}
static void gc_resetTag(Value* x) {
x->mmInfo&= 0x7F;
}
void gc_visitRoots() {
for (u32 i = 0; i < gc_rootSz; i++) gc_roots[i]();
for (u32 i = 0; i < gc_rootObjSz; i++) mm_visitP(gc_rootObjs[i]);
for (u32 i = 0; i < gc_rootBRefsSz; i++) mm_visit(*gc_rootBRefs[i]);
}
static void gc_tryFree(Value* v) {
u8 t = v->type;
#if defined(DEBUG) && !defined(CATCH_ERRORS)
if (t==t_freed) err("GC found t_freed\n");
#endif
if (t!=t_empty && !(v->mmInfo&0x80)) {
if (t==t_shape || t==t_temp || t==t_talloc) return;
#ifdef DONT_FREE
v->flags = t;
#else
#if CATCH_ERRORS
if (t==t_freed) { mm_free(v); return; }
#endif
#endif
#ifdef LOG_GC
gc_freedBytes+= mm_size(v); gc_freedCount++;
#endif
v->type = t_freed;
ptr_inc(v); // required as otherwise the object may free itself while not done reading its own fields
TIi(t,freeO)(v);
tptr_dec(v, mm_free);
// Object may not be immediately freed if it's not a part of a cycle, but instead a descendant of one.
// It will be freed when the cycle is freed, and the t_freed type ensures it doesn't double-free itself
}
}
#ifdef LOG_GC
u64 gc_visitBytes, gc_visitCount, gc_freedBytes, gc_freedCount, gc_unkRefsBytes, gc_unkRefsCount;
#endif
i32 visit_mode;
enum {
GC_DEC_REFC, // decrement refcount
GC_INC_REFC, // increment refcount
GC_MARK, // if unmarked, mark & visit
};
void gc_onVisit(Value* x) {
switch (visit_mode) { default: UD;
case GC_DEC_REFC:
#if DEBUG
if(x->refc==0) err("decrementing refc 0");
#endif
x->refc--;
return;
case GC_INC_REFC: x->refc++; return;
case GC_MARK: {
if (x->mmInfo&0x80) return;
x->mmInfo|= 0x80;
#ifdef LOG_GC
gc_visitBytes+= mm_size(x); gc_visitCount++;
#endif
TIv(x,visit)(x);
return;
}
}
}
static void gcv2_visit(Value* x) {
TIv(x,visit)(x);
}
static void gcv2_unmark_visit(Value* x) {
gc_resetTag(x);
TIv(x,visit)(x);
}
#if HEAP_VERIFY
void gcv2_runHeapverify(i32 mode) {
visit_mode = mode==0? GC_DEC_REFC : GC_INC_REFC;
mm_forHeap(gcv2_visit);
gc_visitRoots();
}
#endif
#if ENABLE_GC
static void gc_visitRefcNonzero(Value* x) {
if (x->refc == 0) return;
#ifdef LOG_GC
gc_unkRefsBytes+= mm_size(x); gc_unkRefsCount++;
#endif
mm_visitP(x);
}
static void gc_run(bool toplevel) {
if (toplevel) {
mm_forHeap(gc_resetTag);
} else {
visit_mode = GC_DEC_REFC;
mm_forHeap(gcv2_unmark_visit);
visit_mode = GC_MARK;
mm_forHeap(gc_visitRefcNonzero);
visit_mode = GC_INC_REFC;
mm_forHeap(gcv2_visit);
}
visit_mode = GC_MARK;
gc_visitRoots();
mm_forHeap(gc_tryFree);
mm_freeFreedAndMerge();
}
#endif
u64 gc_lastAlloc;
void gc_forceGC(bool toplevel) {
#if ENABLE_GC
#ifdef LOG_GC
u64 start = nsTime();
gc_visitBytes = 0; gc_freedBytes = 0;
gc_visitCount = 0; gc_freedCount = 0;
gc_unkRefsBytes = 0; gc_unkRefsCount = 0;
u64 startSize = mm_heapUsed();
#endif
gc_run(toplevel);
u64 endSize = mm_heapUsed();
#ifdef LOG_GC
fprintf(stderr, "GC kept "N64d"B/"N64d" objs, freed "N64d"B, incl. directly "N64d"B/"N64d" objs", gc_visitBytes, gc_visitCount, startSize-endSize, gc_freedBytes, gc_freedCount);
fprintf(stderr, "; unknown refs: "N64d"B/"N64d" objs", gc_unkRefsBytes, gc_unkRefsCount);
fprintf(stderr, "; took %.3fms\n", (nsTime()-start)/1e6);
#endif
gc_lastAlloc = endSize;
#endif
}
static bool gc_wantTopLevelGC;
bool gc_maybeGC(bool toplevel) {
if (gc_depth) return false;
u64 used = mm_heapUsed();
if (used > gc_lastAlloc*2 || (toplevel && gc_wantTopLevelGC)) {
if (toplevel) gc_wantTopLevelGC = false;
gc_forceGC(toplevel);
return true;
}
return false;
}