runtime: add types to MSpan

R=rsc
CC=golang-dev
https://golang.org/cl/6554060

src/pkg/runtime/malloc.goc

@@ -43,6 +43,9 @@ runtime·mallocgc(uintptr size, uint32 flag, int32 dogc, int32 zeroed)
 	if(size == 0)
 		size = 1;
 
+	if(DebugTypeAtBlockEnd)
+		size += sizeof(uintptr);
+
 	c = m->mcache;
 	c->local_nmalloc++;
 	if(size <= MaxSmallSize) {
@@ -84,6 +87,9 @@ runtime·mallocgc(uintptr size, uint32 flag, int32 dogc, int32 zeroed)
 	if(!(flag & FlagNoGC))
 		runtime·markallocated(v, size, (flag&FlagNoPointers) != 0);
 
+	if(DebugTypeAtBlockEnd)
+		*(uintptr*)((uintptr)v+size-sizeof(uintptr)) = 0;
+
 	m->mallocing = 0;
 
 	if(!(flag & FlagNoProfiling) && (rate = runtime·MemProfileRate) > 0) {
@@ -213,7 +219,7 @@ runtime·mlookup(void *v, byte **base, uintptr *size, MSpan **sp)
 		return 0;
 	}
 
-	n = runtime·class_to_size[s->sizeclass];
+	n = s->elemsize;
 	if(base) {
 		i = ((byte*)v - p)/n;
 		*base = p + i*n;
@@ -450,6 +456,220 @@ runtime·MHeap_SysAlloc(MHeap *h, uintptr n)
 	return p;
 }
 
+static Lock settype_lock;
+
+void
+runtime·settype_flush(M *m, bool sysalloc)
+{
+	uintptr *buf, *endbuf;
+	uintptr size, ofs, j, t;
+	uintptr ntypes, nbytes2, nbytes3;
+	uintptr *data2;
+	byte *data3;
+	bool sysalloc3;
+	void *v;
+	uintptr typ, p;
+	MSpan *s;
+
+	buf = m->settype_buf;
+	endbuf = buf + m->settype_bufsize;
+
+	runtime·lock(&settype_lock);
+	while(buf < endbuf) {
+		v = (void*)*buf;
+		*buf = 0;
+		buf++;
+		typ = *buf;
+		buf++;
+
+		// (Manually inlined copy of runtime·MHeap_Lookup)
+		p = (uintptr)v>>PageShift;
+		if(sizeof(void*) == 8)
+			p -= (uintptr)runtime·mheap.arena_start >> PageShift;
+		s = runtime·mheap.map[p];
+
+		if(s->sizeclass == 0) {
+			s->types.compression = MTypes_Single;
+			s->types.data = typ;
+			continue;
+		}
+
+		size = s->elemsize;
+		ofs = ((uintptr)v - (s->start<<PageShift)) / size;
+
+		switch(s->types.compression) {
+		case MTypes_Empty:
+			ntypes = (s->npages << PageShift) / size;
+			nbytes3 = 8*sizeof(uintptr) + 1*ntypes;
+
+			if(!sysalloc) {
+				data3 = runtime·mallocgc(nbytes3, FlagNoPointers, 0, 1);
+			} else {
+				data3 = runtime·SysAlloc(nbytes3);
+				if(0) runtime·printf("settype(0->3): SysAlloc(%x) --> %p\n", (uint32)nbytes3, data3);
+			}
+
+			s->types.compression = MTypes_Bytes;
+			s->types.sysalloc = sysalloc;
+			s->types.data = (uintptr)data3;
+
+			((uintptr*)data3)[1] = typ;
+			data3[8*sizeof(uintptr) + ofs] = 1;
+			break;
+
+		case MTypes_Words:
+			((uintptr*)s->types.data)[ofs] = typ;
+			break;
+
+		case MTypes_Bytes:
+			data3 = (byte*)s->types.data;
+			for(j=1; j<8; j++) {
+				if(((uintptr*)data3)[j] == typ) {
+					break;
+				}
+				if(((uintptr*)data3)[j] == 0) {
+					((uintptr*)data3)[j] = typ;
+					break;
+				}
+			}
+			if(j < 8) {
+				data3[8*sizeof(uintptr) + ofs] = j;
+			} else {
+				ntypes = (s->npages << PageShift) / size;
+				nbytes2 = ntypes * sizeof(uintptr);
+
+				if(!sysalloc) {
+					data2 = runtime·mallocgc(nbytes2, FlagNoPointers, 0, 1);
+				} else {
+					data2 = runtime·SysAlloc(nbytes2);
+					if(0) runtime·printf("settype.(3->2): SysAlloc(%x) --> %p\n", (uint32)nbytes2, data2);
+				}
+
+				sysalloc3 = s->types.sysalloc;
+
+				s->types.compression = MTypes_Words;
+				s->types.sysalloc = sysalloc;
+				s->types.data = (uintptr)data2;
+
+				// Move the contents of data3 to data2. Then deallocate data3.
+				for(j=0; j<ntypes; j++) {
+					t = data3[8*sizeof(uintptr) + j];
+					t = ((uintptr*)data3)[t];
+					data2[j] = t;
+				}
+				if(sysalloc3) {
+					nbytes3 = 8*sizeof(uintptr) + 1*ntypes;
+					if(0) runtime·printf("settype.(3->2): SysFree(%p,%x)\n", data3, (uint32)nbytes3);
+					runtime·SysFree(data3, nbytes3);
+				}
+
+				data2[ofs] = typ;
+			}
+			break;
+		}
+	}
+	runtime·unlock(&settype_lock);
+
+	m->settype_bufsize = 0;
+}
+
+// It is forbidden to use this function if it is possible that
+// explicit deallocation via calling runtime·free(v) may happen.
+void
+runtime·settype(void *v, uintptr t)
+{
+	M *m1;
+	uintptr *buf;
+	uintptr i;
+	MSpan *s;
+
+	if(t == 0)
+		runtime·throw("settype: zero type");
+
+	m1 = m;
+	buf = m1->settype_buf;
+	i = m1->settype_bufsize;
+	buf[i+0] = (uintptr)v;
+	buf[i+1] = t;
+	i += 2;
+	m1->settype_bufsize = i;
+
+	if(i == nelem(m1->settype_buf)) {
+		runtime·settype_flush(m1, false);
+	}
+
+	if(DebugTypeAtBlockEnd) {
+		s = runtime·MHeap_Lookup(&runtime·mheap, v);
+		*(uintptr*)((uintptr)v+s->elemsize-sizeof(uintptr)) = t;
+	}
+}
+
+void
+runtime·settype_sysfree(MSpan *s)
+{
+	uintptr ntypes, nbytes;
+
+	if(!s->types.sysalloc)
+		return;
+
+	nbytes = (uintptr)-1;
+
+	switch (s->types.compression) {
+	case MTypes_Words:
+		ntypes = (s->npages << PageShift) / s->elemsize;
+		nbytes = ntypes * sizeof(uintptr);
+		break;
+	case MTypes_Bytes:
+		ntypes = (s->npages << PageShift) / s->elemsize;
+		nbytes = 8*sizeof(uintptr) + 1*ntypes;
+		break;
+	}
+
+	if(nbytes != (uintptr)-1) {
+		if(0) runtime·printf("settype: SysFree(%p,%x)\n", (void*)s->types.data, (uint32)nbytes);
+		runtime·SysFree((void*)s->types.data, nbytes);
+	}
+}
+
+uintptr
+runtime·gettype(void *v)
+{
+	MSpan *s;
+	uintptr t, ofs;
+	byte *data;
+
+	s = runtime·MHeap_LookupMaybe(&runtime·mheap, v);
+	if(s != nil) {
+		t = 0;
+		switch(s->types.compression) {
+		case MTypes_Empty:
+			break;
+		case MTypes_Single:
+			t = s->types.data;
+			break;
+		case MTypes_Words:
+			ofs = (uintptr)v - (s->start<<PageShift);
+			t = ((uintptr*)s->types.data)[ofs/s->elemsize];
+			break;
+		case MTypes_Bytes:
+			ofs = (uintptr)v - (s->start<<PageShift);
+			data = (byte*)s->types.data;
+			t = data[8*sizeof(uintptr) + ofs/s->elemsize];
+			t = ((uintptr*)data)[t];
+			break;
+		default:
+			runtime·throw("runtime·gettype: invalid compression kind");
+		}
+		if(0) {
+			runtime·lock(&settype_lock);
+			runtime·printf("%p -> %d,%X\n", v, (int32)s->types.compression, (int64)t);
+			runtime·unlock(&settype_lock);
+		}
+		return t;
+	}
+	return 0;
+}
+
 // Runtime stubs.
 
 void*
@@ -461,6 +681,14 @@ runtime·mal(uintptr n)
 func new(typ *Type) (ret *uint8) {
 	uint32 flag = typ->kind&KindNoPointers ? FlagNoPointers : 0;
 	ret = runtime·mallocgc(typ->size, flag, 1, 1);
+
+	if(UseSpanType && !flag) {
+		if(false) {
+			runtime·printf("new %S: %p\n", *typ->string, ret);
+		}
+		runtime·settype(ret, (uintptr)typ | TypeInfo_SingleObject);
+	}
+
 	FLUSH(&ret);
 }
 

src/pkg/runtime/malloc.h

@@ -85,6 +85,7 @@ typedef struct MHeap	MHeap;
 typedef struct MSpan	MSpan;
 typedef struct MStats	MStats;
 typedef struct MLink	MLink;
+typedef struct MTypes	MTypes;
 
 enum
 {
@@ -303,6 +304,44 @@ void*	runtime·MCache_Alloc(MCache *c, int32 sizeclass, uintptr size, int32 zero
 void	runtime·MCache_Free(MCache *c, void *p, int32 sizeclass, uintptr size);
 void	runtime·MCache_ReleaseAll(MCache *c);
 
+// MTypes describes the types of blocks allocated within a span.
+// The compression field describes the layout of the data.
+//
+// MTypes_Empty:
+//     All blocks are free, or no type information is available for
+//     allocated blocks.
+//     The data field has no meaning.
+// MTypes_Single:
+//     The span contains just one block.
+//     The data field holds the type information.
+//     The sysalloc field has no meaning.
+// MTypes_Words:
+//     The span contains multiple blocks.
+//     The data field points to an array of type [NumBlocks]uintptr,
+//     and each element of the array holds the type of the corresponding
+//     block.
+// MTypes_Bytes:
+//     The span contains at most seven different types of blocks.
+//     The data field points to the following structure:
+//         struct {
+//             type  [8]uintptr       // type[0] is always 0
+//             index [NumBlocks]byte
+//         }
+//     The type of the i-th block is: data.type[data.index[i]]
+enum
+{
+	MTypes_Empty = 0,
+	MTypes_Single = 1,
+	MTypes_Words = 2,
+	MTypes_Bytes = 3,
+};
+struct MTypes
+{
+	byte	compression;	// one of MTypes_*
+	bool	sysalloc;	// whether (void*)data is from runtime·SysAlloc
+	uintptr	data;
+};
+
 // An MSpan is a run of pages.
 enum
 {
@@ -320,10 +359,12 @@ struct MSpan
 	MLink	*freelist;	// list of free objects
 	uint32	ref;		// number of allocated objects in this span
 	uint32	sizeclass;	// size class
+	uintptr	elemsize;	// computed from sizeclass or from npages
 	uint32	state;		// MSpanInUse etc
 	int64   unusedsince;	// First time spotted by GC in MSpanFree state
 	uintptr npreleased;	// number of pages released to the OS
 	byte	*limit;		// end of data in span
+	MTypes	types;		// types of allocated objects in this span
 };
 
 void	runtime·MSpan_Init(MSpan *span, PageID start, uintptr npages);
@@ -412,6 +453,11 @@ bool	runtime·blockspecial(void*);
 void	runtime·setblockspecial(void*, bool);
 void	runtime·purgecachedstats(MCache*);
 
+void	runtime·settype(void*, uintptr);
+void	runtime·settype_flush(M*, bool);
+void	runtime·settype_sysfree(MSpan*);
+uintptr	runtime·gettype(void*);
+
 enum
 {
 	// flags to malloc
@@ -429,3 +475,13 @@ void	runtime·gchelper(void);
 
 bool	runtime·getfinalizer(void *p, bool del, void (**fn)(void*), uintptr *nret);
 void	runtime·walkfintab(void (*fn)(void*));
+
+enum
+{
+	TypeInfo_SingleObject = 0,
+	TypeInfo_Array = 1,
+	TypeInfo_Map = 2,
+
+	// Enables type information at the end of blocks allocated from heap	
+	DebugTypeAtBlockEnd = 0,
+};

src/pkg/runtime/mgc0.c

@@ -596,6 +596,8 @@ addroots(void)
 	G *gp;
 	FinBlock *fb;
 	byte *p;
+	MSpan *s, **allspans;
+	uint32 spanidx;
 
 	work.nroot = 0;
 
@@ -603,6 +605,23 @@ addroots(void)
 	for(p=data; p<ebss; p+=DataBlock)
 		addroot(p, p+DataBlock < ebss ? DataBlock : ebss-p);
 
+	// MSpan.types
+	allspans = runtime·mheap.allspans;
+	for(spanidx=0; spanidx<runtime·mheap.nspan; spanidx++) {
+		s = allspans[spanidx];
+		if(s->state == MSpanInUse) {
+			switch(s->types.compression) {
+			case MTypes_Empty:
+			case MTypes_Single:
+				break;
+			case MTypes_Words:
+			case MTypes_Bytes:
+				addroot((byte*)&s->types.data, sizeof(void*));
+				break;
+			}
+		}
+	}
+
 	for(gp=runtime·allg; gp!=nil; gp=gp->alllink) {
 		switch(gp->status){
 		default:
@@ -675,8 +694,11 @@ sweepspan(ParFor *desc, uint32 idx)
 	byte *p;
 	MCache *c;
 	byte *arena_start;
-	MLink *start, *end;
+	MLink head, *end;
 	int32 nfree;
+	byte *type_data;
+	byte compression;
+	uintptr type_data_inc;
 	MSpan *s;
 
 	USED(&desc);
@@ -690,23 +712,32 @@ sweepspan(ParFor *desc, uint32 idx)
 	arena_start = runtime·mheap.arena_start;
 	p = (byte*)(s->start << PageShift);
 	cl = s->sizeclass;
+	size = s->elemsize;
 	if(cl == 0) {
-		size = s->npages<<PageShift;
 		n = 1;
 	} else {
 		// Chunk full of small blocks.
-		size = runtime·class_to_size[cl];
 		npages = runtime·class_to_allocnpages[cl];
 		n = (npages << PageShift) / size;
 	}
 	nfree = 0;
-	start = end = nil;
+	end = &head;
 	c = m->mcache;
 	
+	type_data = (byte*)s->types.data;
+	type_data_inc = sizeof(uintptr);
+	compression = s->types.compression;
+	switch(compression) {
+	case MTypes_Bytes:
+		type_data += 8*sizeof(uintptr);
+		type_data_inc = 1;
+		break;
+	}
+
 	// Sweep through n objects of given size starting at p.
 	// This thread owns the span now, so it can manipulate
 	// the block bitmap without atomic operations.
-	for(; n > 0; n--, p += size) {
+	for(; n > 0; n--, p += size, type_data+=type_data_inc) {
 		uintptr off, *bitp, shift, bits;
 
 		off = (uintptr*)p - (uintptr*)arena_start;
@@ -738,7 +769,7 @@ sweepspan(ParFor *desc, uint32 idx)
 		// Mark freed; restore block boundary bit.
 		*bitp = (*bitp & ~(bitMask<<shift)) | (bitBlockBoundary<<shift);
 
-		if(s->sizeclass == 0) {
+		if(cl == 0) {
 			// Free large span.
 			runtime·unmarkspan(p, 1<<PageShift);
 			*(uintptr*)p = 1;	// needs zeroing
@@ -747,24 +778,30 @@ sweepspan(ParFor *desc, uint32 idx)
 			c->local_nfree++;
 		} else {
 			// Free small object.
+			switch(compression) {
+			case MTypes_Words:
+				*(uintptr*)type_data = 0;
+				break;
+			case MTypes_Bytes:
+				*(byte*)type_data = 0;
+				break;
+			}
 			if(size > sizeof(uintptr))
 				((uintptr*)p)[1] = 1;	// mark as "needs to be zeroed"
-			if(nfree)
+			
-				end->next = (MLink*)p;
+			end->next = (MLink*)p;
-			else
-				start = (MLink*)p;
 			end = (MLink*)p;
 			nfree++;
 		}
 	}
 
 	if(nfree) {
-		c->local_by_size[s->sizeclass].nfree += nfree;
+		c->local_by_size[cl].nfree += nfree;
 		c->local_alloc -= size * nfree;
 		c->local_nfree += nfree;
 		c->local_cachealloc -= nfree * size;
 		c->local_objects -= nfree;
-		runtime·MCentral_FreeSpan(&runtime·mheap.central[cl], s, nfree, start, end);
+		runtime·MCentral_FreeSpan(&runtime·mheap.central[cl], s, nfree, head.next, end);
 	}
 }
 
@@ -851,6 +888,7 @@ runtime·gc(int32 force)
 	uint64 heap0, heap1, obj0, obj1;
 	byte *p;
 	GCStats stats;
+	M *m1;
 	uint32 i;
 
 	// The gc is turned off (via enablegc) until
@@ -891,6 +929,9 @@ runtime·gc(int32 force)
 	m->gcing = 1;
 	runtime·stoptheworld();
 
+	for(m1=runtime·allm; m1; m1=m1->alllink)
+		runtime·settype_flush(m1, false);
+
 	heap0 = 0;
 	obj0 = 0;
 	if(gctrace) {

src/pkg/runtime/mheap.c

@@ -143,6 +143,8 @@ HaveSpan:
 	// Record span info, because gc needs to be
 	// able to map interior pointer to containing span.
 	s->sizeclass = sizeclass;
+	s->elemsize = (sizeclass==0 ? s->npages<<PageShift : runtime·class_to_size[sizeclass]);
+	s->types.compression = MTypes_Empty;
 	p = s->start;
 	if(sizeof(void*) == 8)
 		p -= ((uintptr)h->arena_start>>PageShift);
@@ -288,6 +290,10 @@ MHeap_FreeLocked(MHeap *h, MSpan *s)
 	MSpan *t;
 	PageID p;
 
+	if(s->types.sysalloc)
+		runtime·settype_sysfree(s);
+	s->types.compression = MTypes_Empty;
+
 	if(s->state != MSpanInUse || s->ref != 0) {
 		runtime·printf("MHeap_FreeLocked - span %p ptr %p state %d ref %d\n", s, s->start<<PageShift, s->state, s->ref);
 		runtime·throw("MHeap_FreeLocked - invalid free");
@@ -426,9 +432,11 @@ runtime·MSpan_Init(MSpan *span, PageID start, uintptr npages)
 	span->freelist = nil;
 	span->ref = 0;
 	span->sizeclass = 0;
+	span->elemsize = 0;
 	span->state = 0;
 	span->unusedsince = 0;
 	span->npreleased = 0;
+	span->types.compression = MTypes_Empty;
 }
 
 // Initialize an empty doubly-linked list.

src/pkg/runtime/runtime.h

@@ -268,6 +268,9 @@ struct	M
 	uint32	waitsemalock;
 	GCStats	gcstats;
 
+	uintptr	settype_buf[1024];
+	uintptr	settype_bufsize;
+
 #ifdef GOOS_windows
 	void*	thread;		// thread handle
 #endif
@@ -836,3 +839,8 @@ extern uint64 ·nan;
 extern uint64 ·posinf;
 extern uint64 ·neginf;
 #define ISNAN(f) ((f) != (f))
+
+enum
+{
+	UseSpanType = 1,
+};